WO2020080516A1 - Apparatus for analyzing change in physical property near solid-liquid interface and method for analyzing change in physical property near solid-liquid interface - Google Patents

Abstract

The purpose of the present invention is to provide an apparatus and a method capable of analyzing a change over time in the physical properties of liquid near a solid-liquid interface. This apparatus for analyzing a change in physical properties near a solid-liquid interface comprises: a vibrator disposed in liquid that forms a solid-liquid interface; a physical property control unit which controls the physical properties of liquid near the solid-liquid interface; an excitation unit which vibrates the vibrator; a motion state analysis unit which analyzes a motion state of the vibrator; and a time-series recording unit which records, in time series, control information obtained by the physical property control unit and the motion state obtained by the motion state analysis unit.

Description

Apparatus for analyzing physical property change near solid-liquid interface and method for analyzing change in physical property near solid-liquid interface

The present invention relates to a technique for analyzing changes in physical properties that occur near the solid-liquid interface. More specifically, the present invention relates to a physical property change analyzer near a solid-liquid interface and a method for analyzing a physical property change near a solid-liquid interface.

In an electrochemical device that includes an electrode and an electrolytic solution, the state of the electrolytic solution is greatly affected by device operation and device performance. In particular, it is important to understand the substance concentration of the electrolytic solution. So far, as the substance concentration method of the electrolytic solution, general-purpose methods such as a solution titration method, a precipitation method, an ion chromatography method, an electrochemical measurement method, and an absorption spectroscopy method have been established. It is assumed to be homogeneous.

On the other hand, a scanning method using an atomic force microscope is known as a method for analyzing an interface (solid-liquid interface) between a solid and a liquid. As shown in FIG. 7, for example, an atomic force microscope moves a small leaf spring called a cantilever up and down to move inside a solid-liquid interface, and traces the surface of the solid with the cantilever to image the unevenness information. It is a thing.

In recent years, not only imaging using solid-state surface roughness information using an atomic force microscope, but also a method of quantifying material properties at the solid-liquid interface and mapping the quantitative information to the solid surface for imaging are also known. (Non-patent document 1).

The physical properties of the liquid near the interface between the solid and the liquid change due to the chemical reaction between the solid and the liquid. For example, at an electrochemical interface where a solid is composed of electrodes and a liquid is composed of an electrolytic solution, the concentration of the electrolytic solution in the vicinity of the electrodes changes extremely locally due to an electrochemical reaction. Such an electrochemical interface is an important place to support the operation of various electrochemical devices such as batteries, capacitors and biosensors, and the chemical reaction processes of materials such as electrolytic refining, plating and catalytic reaction. ing. In addition, understanding such local changes over time, that is, operand measurement, which directly measures the production environment of the debass or the reaction environment of the material, enables a correct understanding of the device operation or the material reaction process. , Is important in improving its performance and / or efficiency.

However, the conventional electrolyte concentration measurement methods are based on the assumption that the entire electrolyte is homogeneous, so it is not possible to measure locally different substance concentrations in the vicinity of the electrochemical interface.

On the other hand, it is possible to measure the local concentration in the vicinity of the electrochemical interface by using the atomic force microscope, but since the atomic force microscope is a device specially configured for imaging, , It is not configured to measure local concentration changes in the vicinity of the electrochemical interface over time.

The image to be obtained with the atomic force microscope is a two-dimensional collection of information mapped for each coordinate. That is, basically only one kind of information is recorded in one coordinate (rest position) in the atomic force microscope. For this reason, since it is not assumed that different states are measured with time in one coordinate, the atomic force microscope does not have such a function specialized for measuring different states with time. .

The configuration of the atomic force microscope is schematically shown in Fig. 7. Since the atomic force microscope is based on a design concept specialized for imaging, it is fundamental and indispensable to control the motion state of the cantilever in the process of two-dimensional scanning. Therefore, for example, in the scan mode in which surface irregularities are recorded and imaged, feedback control is always performed so that the motion state of the cantilever is stable and constant with respect to variations in the height direction (for example, feedback in FIG. Control unit). In the scan mode (force curve mapping), which acquires the physical property information of the surface in two dimensions and images it, two-dimensional imaging is performed based on changes in the motion state of the cantilever. The motion state is controlled to a certain degree so that the motion state (motion state at the stationary position where the two-dimensional scanning is stopped) becomes constant (motion state correction unit in FIG. 7). That is, the difference in the surface physical properties at each x, y coordinate point of the two-dimensional mapping is recorded by the deviation between the motion state measured at each coordinate value and the motion state at the basic stationary position, so at the basic stationary position. Automatic correction needs to be performed so that the motion state is always constant.

As described above, in the atomic force microscope for two-dimensional scanning, feedback control and automatic correction control are performed so that the motion state of the cantilever in the scan stationary state is always constant in any scan mode. There is. In other words, if the motional state of the cantilever at the basic rest position is time-sequentially modulated by the change in liquid physical properties at the solid-liquid interface, an operating mechanism that artificially makes the reference motional state of the cantilever occur, The motion state is constantly corrected. Therefore, in an atomic force microscope for two-dimensional imaging, it is extremely difficult to keep track of time-series motion state changes at a stationary position because of the design essential for that purpose. The larger the change in physical properties, the more difficult it becomes to record changes in movement status in time series.

Therefore, an object of the present invention is to provide an apparatus and method capable of analyzing a change in physical properties of a liquid in the vicinity of a solid-liquid interface over time.

As a result of diligent study, the present inventor has arranged a vibrator in the vicinity of a solid-liquid interface to vibrate it, while controlling liquid physical properties in the vicinity of the solid-liquid interface, and at the same time provides control information on the liquid physical properties and the motion state of the vibrator. It was found that the change in physical properties of the liquid near the solid-liquid interface can be analyzed over time by recording in time series. The present invention has been completed by further studies based on this finding.

That is, the present invention provides the inventions of the following modes.
Item 1. A vibrator A arranged in a liquid forming a solid-liquid interface,
An excitation unit B for vibrating the vibrator,
A physical property control unit C for controlling the physical properties of the liquid in the vicinity of the solid-liquid interface,
A motion state analysis unit D that analyzes the motion state of the oscillator A;
A time-series recording unit E that records the control information by the physical property control unit C and the motion state obtained by the motion state analysis unit in time series,
An apparatus for analyzing changes in physical properties near the solid-liquid interface, including
Item 2. The time series recording unit E further records displacement information of the vibrator A and / or vibration direction position information of the vibrator in time series,
Item 2. The physical property change analysis apparatus according to Item 1, wherein the motion state analysis unit D analyzes the motion state from the displacement information and / or the vibration direction position information.
Item 3. It further includes a physical property deriving unit F that derives physical properties from the motion state obtained by the motion state analysis unit D, and an output unit G that outputs a temporal change of the control information in association with the temporal change of the physical property. Item 1. The physical property change analysis device according to item 1 or 2.
Item 4. 4. The physical property change analysis apparatus according to any one of Items 1 to 3, wherein the vibrator A is a cantilever having no probe at its free end.
Item 5. Item 5. The physical property change analyzer near the solid-liquid interface according to any one of Items 1 to 4, wherein the vibrator A does not have a through hole penetrating in the vibration direction.
Item 6. Item 6. The physical property change analysis apparatus in the vicinity of the solid-liquid interface according to any one of Items 1 to 5, further comprising a cell containing the solid-liquid interface.
Item 7. Item 7. The physical property change analyzer near the solid-liquid interface according to any one of Items 1 to 6, wherein the solid-liquid interface is an electrochemical interface, and the control information is current and voltage information.
Item 8. An exciting step of vibrating a vibrator arranged in a liquid forming a solid-liquid interface,
A physical property control step of controlling the liquid physical properties in the vicinity of the solid-liquid interface,
A motion state analysis step of analyzing the motion state of the oscillator;
A time-series recording step of obtaining control information in the physical property control step and the motion state obtained in the motion state analysis step in a state recorded in time series,
A method for analyzing changes in physical properties near the solid-liquid interface, including.
Item 9. Further comprising a preliminary information time series recording step of recording displacement information of the vibrator and / or vibration direction position information of the vibrator in time series,
9. In the motion state analysis step, the change of physical properties in the vicinity of the solid-liquid interface according to item 8 is analyzed, in which the motion state is analyzed from the displacement information and / or the vibration direction position information recorded in the preliminary information time series recording step. How to parse.
Item 10. 10. The method for analyzing a change in physical properties in the vicinity of a solid-liquid interface according to Item 8 or 9, wherein the motion state is obtained as an energy dissipation value or a resonance angular frequency in the motion information analysis step.
Item 11. Item 11. The method for analyzing a change in physical properties in the vicinity of a solid-liquid interface according to any one of Items 8 to 10, wherein the oscillator is vibrated with a triangular wave.
Item 12. 12. The method for analyzing physical property change in the vicinity of a solid-liquid interface according to any one of Items 8 to 11, wherein the solid-liquid interface is an electrochemical interface, and the control information is current and voltage information.
Item 13. In order to analyze the physical properties near the solid-liquid interface, the computer
A procedure for analyzing the motion state of an oscillator arranged in a liquid that forms a solid-liquid interface,
A procedure for recording the motion state and control information relating to control of liquid physical properties in the vicinity of the solid-liquid interface in time series,
A program for analyzing the physical properties near the solid-liquid interface for executing
Item 14. In order to analyze the physical properties near the solid-liquid interface, the computer
A step of analyzing a motion state of an oscillator arranged in a liquid forming a solid-liquid interface and moving along the solid-liquid interface;
A step of obtaining a two-dimensional mapping image in which the position of the moving oscillator and the motion state of the oscillator at the position correspond to each other;
A procedure of obtaining an average value of the motion state at each of predetermined moving distances equally divided from the total moving distance of the oscillator;
A procedure of converting each of the average values of the motion state into a time series of movement of the oscillator,
A procedure of recording the average value of the motion state and control information regarding control of liquid physical properties near the solid-liquid interface in time series,
A program for analyzing the physical properties near the solid-liquid interface for executing

According to the present invention, there is provided an apparatus and method capable of analyzing changes in physical properties of a liquid in the vicinity of a solid-liquid interface over time.

It is a block diagram which shows an example of the physical-property change analysis apparatus of solid-liquid interface vicinity of this invention. FIG. 6 is a schematic diagram illustrating a difference in vibration mode of a vibrator due to a difference in concentration near a solid-liquid interface. It is a schematic diagram explaining the difference in the vibration mode of a vibrator by the difference in the lithium concentration near the electrochemical interface. The difference in the change of the position, acceleration and velocity of the vibrator due to the difference of the vibration wave of the vibrator is shown. FIG. 5 is a schematic diagram illustrating a method of analyzing a change in physical properties near a solid-liquid interface in Examples. It is a result of the analysis method of the physical property change in the vicinity of the solid-liquid interface obtained in the example. It is a block diagram which shows an atomic force microscope.

[1. Physical property change analyzer near solid-liquid interface]
The physical property change analyzer near the solid-liquid interface of the present invention is an apparatus for analyzing a physical property change locally occurring in the vicinity of the solid-liquid interface, and the motion state of a vibrator vibrated in a solution near the solid-liquid interface is fixed. By taking advantage of the fact that it changes over time with changes in the physical properties near the liquid interface, by recording the changes over time in the motion state together with the physical property control information near the solid-liquid interface in a time series, the physical properties near the solid-liquid interface can be recorded. Analyze changes.

[1-1. Basic configuration]
FIG. 1 is a block diagram showing an example of the physical property change analysis apparatus of the present invention near the solid-liquid interface. As shown in FIG. 1, the physical property change analysis apparatus near the solid-liquid interface includes a vibrator A, an excitation unit B (vibrator excitation unit B in the figure), a physical property control unit C (a solid-liquid interface physical property control unit in the drawing). C), a motion state analysis unit D, and a time series recording unit E are included. Further, the physical property change analyzing apparatus in the vicinity of the solid-liquid interface of the present invention includes a cell that accommodates the solid-liquid interface, a displacement detection unit, a vibrator drive unit, a vibration wave generation unit, a physical property derivation unit F, an output unit G, and the like. You can

[1-2. Solid-liquid interface]
The solid-liquid interface to be analyzed by the physical property change analyzer near the solid-liquid interface of the present invention is not limited as long as it is an interface where the solution physical properties locally change near the interface between the solid and the liquid. The physical properties of the solution may be any physical properties such that the solution resistance received by the vibrator, which will be described later, changes due to the change, and usually includes viscosity and density. Therefore, as the physical property change in the present invention, the liquid viscosity and / or density change due to the substance concentration change in the liquid, the liquid viscosity and / or density change due to the density change of the liquid, and the liquid change due to the temperature change of the liquid Viscosity and / or density change and the like can be mentioned. Examples of the solid-liquid interface that locally causes such a change in the physical properties of the solution include an electrochemical interface, a catalytic chemical interface, and a thermal interface. Further, the vicinity of the solid-liquid interface may be a local range in which a change in the physical properties of the liquid occurs, and for example, in the case of an electrochemical interface, it may be a range corresponding to the diffusion layer. A more specific range near the solid-liquid interface is, for example, a position within a range of 0 to 300 μm, preferably 0 to 100 μm from the solid surface.

An electrochemical interface changes the physical properties of a liquid near the surface of a solid by an electrochemical reaction. Specifically, it is composed of an electrode (solid) and an electrolytic solution (liquid). Examples of electrochemical devices having an electrochemical interface include batteries, capacitors, biosensors, and the like, and electrochemical materials involved in the electrochemical interface include electrolytic refining materials, plating materials, and the like. . That is, when an electrochemical interface is an analysis target in the present invention, it is possible to perform operand measurement in the actual environment of these electrochemical devices or the reaction environment of electrochemical materials.

The catalytic chemical interface changes the physical properties of the liquid near the surface of the solid by a catalytic reaction. Specifically, it is composed of a heterogeneous catalyst (solid) and a reaction liquid (liquid). A more specific example of the heterogeneous catalyst is a photocatalyst or the like. That is, in the present invention, when the catalytic chemical interface is an analysis target, it is possible to perform operand measurement in the reaction environment of such a heterogeneous catalyst.

The thermal interface changes the physical properties of the liquid near the surface of the solid due to temperature changes, and is composed of, for example, a temperature changing member (solid) and liquid. A thermoelectric device etc. are mentioned as an example of the device which has a temperature change member. That is, in the present invention, when the thermal interface is the analysis target, the operand measurement in the actual operating environment of such a device becomes possible.

According to the present invention, it is possible to analyze a change in physical property at a fixed position (one coordinate) in a solid-liquid interface, and therefore, an electrochemical liquid reaction between solid and liquid or a catalytic reaction or solid-liquid reaction that causes a change in physical property of a liquid. The thermal change of may be homogeneous over the solid surface, but need not be, and may be non-uniform. When the above-mentioned reaction or change is non-uniform over the entire solid surface, analyze the non-uniformity of the above-mentioned reaction or change on the solid surface by individually analyzing changes in physical properties at various fixed positions within the solid-liquid interface. You can also

[1-3. cell]
The solid-liquid interface is housed in the cell (that is, the solid and liquid constituting the solid-liquid interface are housed in the cell) and is subjected to analysis using a physical property change analyzer near the solid-liquid interface. . The specific configuration of the cell is appropriately designed depending on the type of solid-liquid interface. The cell may be the device as described above or the reaction vessel itself.

The cell may be appropriately prepared by the user, or may be included in the physical property change analyzer near the solid-liquid interface of the present invention. When the cell is included in the physical property change analyzer near the solid-liquid interface of the present invention, the solid and liquid to be contained in the cell may be appropriately prepared by the user, or the solid forming the solid-liquid interface in advance. Either the liquid or the liquid is contained, and the user may prepare the other.

The cell may be a closed type or an open type. A closed cell is more preferable when analyzing the interface between a volatile liquid and a solid, but a closed cell is used when analyzing the interface between a non-volatile liquid and a solid. It may be either open type or open type.

[1-4. Transducer A]
The vibrator is a minute member that is arranged in the vicinity of the solid-liquid interface in the cell and is vibrated in the perspective direction with respect to the solid-liquid interface. The oscillator may be one that receives the resistance of the solution and changes its displacement and / or motion state in response to changes in the physical properties of the solution. For example, a plate-shaped member, a disk-shaped member, or a spherical body bonded to the tip of the member. An arbitrary shape such as a needle-shaped member is used. A preferable example is a plate-shaped cantilever (cantilever) as illustrated. As the cantilever, for example, a cantilever used in an atomic force microscope can be used, but as described below, the present invention utilizes the change over time in the liquid resistance of the oscillator at a specific location within the solid-liquid interface, and thus the cantilever is used. It is preferable not to have a probe, which is indispensable in a normal atomic force microscope, at the free end. Further, in order to reduce the in-liquid resistance with an atomic force microscope, the cantilever is preferably different from that having a through hole penetrating in the vibration direction thereof. To facilitate detection, it is more preferable not to have a through hole that penetrates in the vibration direction.

In the physical property change analysis apparatus of the present invention near the solid-liquid interface, the vibrator is controlled during physical property control and while detecting displacement information, except that the vibrator is vibrated by an excitation unit described later. The proximal end is designed to be immobile.

[1-5. Excitation part B]
An exciting part is provided at the base end (fixed end) of the oscillator, and the exciter vibrates the oscillator in the perspective direction with respect to the solid-liquid interface. In the present invention, the vibrator may vibrate so as to receive the solution resistance. Therefore, the vibration of the oscillator may be any vibration as long as its free end is in a direction including at least the perspective direction with respect to the solid-liquid interface, and is not limited to reciprocating vibration only in the vertical direction with respect to the solid-liquid interface. May be The excitation unit constitutes an excitation unit together with the vibration wave generation unit and the oscillator drive unit, and excites the oscillator by a known mechanism.

The vibration wave generation unit generates a waveform such as a triangular wave or a sine wave (preferably a triangular wave), and vibrates the vibrator with a predetermined waveform via the vibrator drive unit. The vibrator driving unit supplies a control signal regarding the displacement amount and / or the vibration amount to the excitation unit to vibrate the vibrator. For example, when a vibrator is excited by a piezo-excitation mechanism, the excitation unit can be composed of a piezo element and the vibrator drive unit can be composed of a piezo driver. In addition, as a mechanism for exciting the vibrator, a laser light exciting mechanism, a thermal exciting mechanism, a tuning-fork type crystal vibrating mechanism, and the like can be cited, and an exciting unit corresponding to each mechanism can be appropriately configured. The information about the control performed by the vibrator drive unit can be regarded as information corresponding to the vibration direction position information (position information in the figure) of the vibrator, and the control information, that is, the vibration direction position information, will be described later. Can be recorded as a history in the time series recording unit. The vibration direction here means the direction perpendicular to the solid-liquid interface. Further, the position (position in the vibration direction) means the position of the free end of the vibrator during vibration. The vibration width of the vibrator in the vibration direction is, for example, 1 to 300 nm. For example, in an atomic force microscope, it is necessary to scan the solid surface, and the vibration width of the oscillator must be 50 nm or more in order to stabilize the probe movement. However, the larger the vibration width of the oscillator is, the solution near the solid-liquid interface becomes larger. In the physical property change analyzer near the solid-liquid interface of the present invention, since the disturbance tends to occur easily, in consideration of capturing a true aspect regarding the local physical properties near the solid-liquid interface, the vibration width of the oscillator is considered. Is preferably 40 nm or less, more preferably 30 nm or less. The lower limit of the vibration width of the vibrator is preferably 10 nm or more from the viewpoint of more preferably detecting a change in resistance in liquid. Therefore, the preferable range of the vibration width of the vibrator is, for example, 1 to 40 nm, 10 to 40 nm, 1 to 30 nm, and 10 to 30 nm. The vibration speed may be 100 times or more per second.

[1-6. Physical property control section C]
The displacement and / or motion state of the vibrating oscillator changes according to changes in physical properties near the solid-liquid interface. The physical property control unit controls the physical properties of the liquid in the vicinity of the solid-liquid interface. The physical property control unit directly controls the solid that forms the solid-liquid interface, and changes the physical properties of the liquid in the vicinity of the solid-liquid interface with the control. The physical property control unit is appropriately designed according to the type of solid-liquid interface. For example, when the solid at the solid-liquid interface is electrically controlled (for example, an electrochemical interface and a thermal interface), a mechanism capable of adjusting current and voltage can be used as the physical property control unit, When the solid at the solid-liquid interface is photochemically controlled (for example, a catalytic chemical interface), a mechanism capable of adjusting the light intensity can be used as the physical property control unit. Information relating to the control performed by the physical property control unit is once recorded as a control history in “1-9. Time-series recording unit E” described later.

The control level of the physical properties to be controlled (for example, the level of current and voltage for the electrochemical interface or the thermal interface; the level of light intensity for the photochemical interface) is not particularly limited. According to the present invention, it is possible to analyze the change in the physical properties in the vicinity of the solid-liquid interface with excellent accuracy, and thus it is possible to accurately analyze the change in the physical properties due to a slight control level. As a slight control level, for example, an absolute value of the current density with respect to the electrochemical interface is 0.2 mAcm ⁻² or less. On the other hand, as will be described later in “1-7. Displacement detection unit”, in the physical property change analyzer near the solid-liquid interface of the present invention, the solid-liquid interface of Feedback control is always necessary for atomic force microscopes because there is no circuit for feedback control so that the displacement of the cantilever is stable and constant with respect to fluctuations in the height direction (direction perpendicular to the solid-liquid interface). as the control level (eg bring great cantilever displacement as acts, 0.2MAcm ^-2 greater as the absolute value of the current density for an electrochemical interface, preferably 2MAcm ^-2 or more, or more preferably 5MAcm ^-2 or more .), The change in physical properties due to the control level is captured as it is and analyzed. The upper limit of the range of the absolute value of the current density is not particularly limited, for example 12MAcm ^-2 or less, preferably 10MAcm ^-2 or less, or more preferably 8MAcm ^-2 or less. In this case, specific examples of the range of the absolute value of the current density include 0.2 mAcm ^{-2 to} 12 mAcm ^-2 or less, 0.2 mAcm ^{-2 to} 10 mAcm ^-2 or less, and 0.2 mAcm ^{-2 to} 8 mAcm ^-2 or less. 2mAcm ^-2 to 12mAcm ^-2 , 2mAcm ^-2 to 10mAcm ^-2 , 2mAcm ^-2 to 8mAcm ^-2 , 4mAcm ^-2 to 12mAcm ^-2 , 4mAcm ^-2 to 10mAcm ^-2 , 4mAcm ^-2 to 8mAcm ^-2 To be

That is, according to the present invention, it is possible to analyze liquid physical properties in the vicinity of a solid-liquid interface controlled at a wide range including a control level at which feedback control always works in an atomic force microscope.

[1-7. Displacement detector]
The displacement due to the vibration of the vibrator is detected by the displacement detector. The illustrated embodiment shows an optical lever type detection mechanism. In the case of the optical leverage method, the displacement detection unit is composed of a light source, a detector, a preamplifier, etc., and the light (laser light) emitted from the light source (for example, laser light source) is reflected on the back surface of the vibrator, and the reflected light is The light enters the detector, is converted into displacement information (displacement signal) indicating displacement (deflection) of the vibrator by the detector, and the displacement information (displacement signal) is amplified by the preamplifier and then used for analysis of the motion state. This displacement information can be temporarily recorded in “1-9. Time-series recording unit E described later”.

The displacement detection unit is not limited to the optical lever type shown in the figure, but may be configured by a displacement self-detection type detection mechanism, for example. In the displacement self-detection method, a detector (for example, a piezoresistive sensor, a piezoelectric thin film sensor, etc.) is attached to the base end part of the vibrator, and this detector detects the vibrator by the displacement (deflection) of the vibrator. The pressure generated at the base end is detected and converted into displacement information (displacement signal). The displacement self-detection method is preferable in that the detection mechanism can be simplified, and that the cell can be hermetically sealed together with the detector and that the measurement stability is excellent.

Incidentally, in the physical property change analyzer near the solid-liquid interface of the present invention, since it is essential to obtain information about the change over time of the displacement of the oscillator, it is mounted as an essential component in the atomic force microscope, A circuit (for example, a feedback control unit in FIG. 7) for feedback control is provided so that the displacement of the cantilever is stable and constant with respect to fluctuations in the height direction of the solid-liquid interface (direction perpendicular to the solid-liquid interface). Not not.

[1-8. Motion state analysis part D]
The motion state analysis unit uses the vibration direction position information in the vibrator drive unit and / or the displacement information in the displacement detection unit, preferably the vibration direction position information and / or displacement information recorded in the time series recording unit described later. , Analyze the motion state of the oscillator. The motion referred to here is a vibration phenomenon that can be grasped by a physical quantity that can quantify the vibration of the vibrator (for example, resonance angular frequency, energy consumed in one vibration of the vibrator, etc.), and its state The (movement state) is specifically represented by a quantitative value such as a resonance angular frequency and an energy dissipation value.

The motion state analysis unit may be equipped with an algorithm that can analyze the motion state of the oscillator using the vibration direction position information and / or displacement information. Since the method of analyzing the motion state is not particularly limited, it is possible to implement an algorithm based on a known method. Examples of methods for analyzing the motion state include vibration response analysis and energy dissipation analysis.

When the motion state analysis unit implements the algorithm based on the vibration response analysis, the motion state analysis unit uses the vibration direction position information by the vibrator drive unit as the vibration amplitude information, or the displacement information of the vibrator (specifically, Specifically, the vibration amplitude information estimated from the position deviation of the light receiving spot of the optical lever is used, and the vibration amplitude of the vibrator becomes maximum with respect to the excitation frequency (resonance state), that is, the resonance angular frequency. Is obtained as information on the motion state. Then, in this case, in the physical property change analyzer near the solid-liquid interface of the present invention, a feedback control unit that performs feedback from the motion state analysis unit to the oscillator drive unit by using the maximum value of the amplitude as a clue is provided. Enables to track the resonance angular frequency which changes with time.

When the motion state analysis unit implements an algorithm based on energy dissipation analysis, the motion state analysis unit determines the energy in each cycle from the force curve for each cycle of the oscillator obtained from the displacement information and the vibration direction position information. The consumption amount, that is, the energy dissipation value is obtained as the information of the motion state.

The obtained motion state (for example, resonance angular frequency, energy dissipation value, etc.) is recorded in "1-9. Time series recording unit E" described later.

Incidentally, in the physical property change analysis apparatus in the vicinity of the solid-liquid interface of the present invention, it is necessary to capture the change in the motion state of the oscillator during the control of the solid-liquid interface. A circuit (for example, the motion state correction unit in FIG. 7) that corrects when the motion state obtained by the motion state analysis unit exceeds a predetermined level is not provided.

[1-9. Time series recording section E]
The time-series recording unit records information in time series, and is composed of an arbitrary recording medium (storage medium). It is preferably composed of a non-volatile recording medium such as a hard disk. The time-series recording unit records at least information on the motion state (for example, resonance angular frequency, energy dissipation value, etc.) acquired by the motion-state analyzing unit and control information by the physical property control unit in time series. Recording in time series means recording the acquired information in association with a time element. That is, a data set in which the acquired information is synchronized with the control history by the physical property control unit is obtained. Thereby, the change in the exercise state is recorded over time in a state associated with the control information that caused the change.

In the physical property change analyzer near the solid-liquid interface of the present invention, it is necessary to capture the change in the motion state of the oscillator during the control of the solid-liquid interface. The motion state of the oscillator at the different position (one coordinate in the solid-liquid interface) is recorded in time series over the multiple oscillations of the oscillator. The recording rate is, for example, such a degree that 50 to 2000 pieces of motion state information can be recorded per second at a stationary position (one coordinate) in the solid-liquid interface.

In addition to the above information, it is preferable to record the vibration direction position information in the vibrator drive section and / or the displacement information in the displacement detection section in the time series recording section in the same time series as the preliminary information. That is, a data set in which the history of vibration direction position information and / or the change over time of displacement information are associated with time elements is stocked in the sequence recording unit, and the vibration direction position information and / or displacement information is used in the motion state analysis unit. You can leave it ready.

As described above, in the time-series recording unit, the motion state of the oscillator at the fixed position in the solid-liquid interface (one coordinate in the solid-liquid interface) is recorded in time series over the multiple oscillations of the oscillator. Therefore, for example, when force curve measurement is performed from displacement information and vibration direction position information and used for motion state analysis, n points of displacement information and position information are required in the force curve for one vibration of the oscillator, and When the force curve is measured m times per second, n × m sets of displacement information-position information combinations per second at one coordinate can be recorded as preliminary information. From the preliminary information, the motion state analysis unit can obtain m motion state information per second at one coordinate, and the time series recording unit can record m motion state information per second.

Note that, in addition to the above-mentioned information, the time-series recording unit can also record time-series information of physical properties obtained by the physical property deriving unit described later.

[1-10. Physical property derivation part F]
The physical property deriving unit derives the actual physical property of the solution from the information on the motion state of the oscillator obtained by the time series recording unit. The physical property deriving unit only needs to implement an algorithm that can derive the physical properties of the solution from the information on the motion state. The method of deriving the solution physical properties is not particularly limited, and can be appropriately determined according to the type of the motion state analysis method used. For example, it is possible to derive a solution physical property by automatically creating a basic data set showing information on the motion state in various physical properties of the solution and automatically searching for the solution physical property corresponding to the acquired motion information quantitatively. it can.

[1-11. Output part G]
The output unit can display the relationship between time and motion state or the relationship between time and specific solution physical properties in an arbitrary format corresponding to the physical property control information. The output format is not particularly limited as long as it can recognize the change in the solution physical properties associated with the physical property control information. For example, the motion state or specific solution physical properties and control information are developed in parallel axes with respect to the time axis. Examples include graph formats.

[1-12. Other]
In the physical property change analyzer near the solid-liquid interface of the present invention, since it is necessary to capture the change in the motion state of the oscillator during the control of the solid-liquid interface, a fixed position within the solid-liquid interface ( It suffices if the motion state of the vibrator at one coordinate) can be recorded in time series over a plurality of vibrations of the vibrator. Therefore, the function of moving the oscillator within the solid-liquid interface during measurement is not necessary. If the oscillator moves inside the solid-liquid interface during measurement, the solution near the interface will be disturbed, so considering the true aspect of the physical properties near the solid-liquid interface, the vibration inside the solid-liquid interface during measurement will occur. It is important not to move the child. In addition, from the viewpoint of identifying the reaction site and the unreacted site on the solid-liquid interface, do not move the oscillator inside the solid-liquid interface during measurement in order to determine whether or not the reaction is occurring just below the oscillator. Is important.

Further, as described in the above “1-7. Displacement detection unit”, the oscillator is moved by feedback in the vertical direction of the solid-liquid interface during measurement (the movement does not include vertical movement due to vibration). It has no function. Therefore, in the physical property change analyzer near the solid-liquid interface of the present invention, the z-direction moving means controlled by the scanner and the feedback circuit, which is included in the atomic force microscope as an essential component, scans in the xy plane during measurement. Is not provided. However, a means for moving the oscillator in a direction perpendicular to the solid-liquid interface and an inward direction of the solid-liquid interface for the purpose of bringing the oscillator close to the solid-liquid interface and selecting a measurement point of the oscillator in the solid-liquid interface. May be provided. Examples of such moving means include a driving device such as a manual screw system, a motor drive system, and a piezoelectric element (piezo) system.

[2. Method to analyze changes in physical properties near solid-liquid interface]
The method of analyzing the physical property change near the solid-liquid interface of the present invention is that the motion state of the oscillator vibrated in the solution near the solid-liquid interface changes with time along with the physical property change near the solid-liquid interface. This is a method of analyzing the physical property change in the vicinity of the solid-liquid interface by utilizing the time-series recording of the temporal change of the motion state together with the physical property control information in the vicinity of the solid-liquid interface.

[2-1. Basic process]
The method for analyzing the physical property change near the solid-liquid interface of the present invention includes an excitation step, a physical property control step, a motion state analysis step, and a time series recording step. The method of analyzing the physical property change in the vicinity of the solid-liquid interface of the present invention can be carried out using the physical property change analyzer in the vicinity of the solid-liquid interface described in "1. Physical property change analyzer in the vicinity of solid-liquid interface". .

[2-2. Excitation process]
In the excitation step, the vibrator arranged in the liquid forming the solid-liquid interface is vibrated. The excitation step can be performed by using the excitation unit (and an excitation unit including the same) for the oscillator in the above-described physical property change analysis apparatus near the solid-liquid interface. The details of the specific mode for vibrating is as described in "1-2. Solid-liquid interface" to "1-5. Excitation section B".

[2-3. Physical property control process]
In the physical property control step, liquid physical properties near the solid-liquid interface are controlled. The specific mode of controlling the physical properties of the liquid is as described in the above “1-6. Physical property control section C”. In addition, as described in “Energy dissipation analysis” in “2-5. Motion state analysis process” to be described later, from the viewpoint of simplification of analysis, the vibration wave that excites the oscillator is adopted in a normal atomic force microscope. The triangular wave is preferable to the sine wave that is used.

[2-4. Displacement detection process]
The displacement caused by the vibration of the vibrator is detected using a mechanism that detects the displacement (displacement detection step). The mechanism for detecting the displacement is not particularly limited, but as described in the above “1-7. Displacement detection unit”, the optical leverage method, the displacement self-detection method and the like can be mentioned. Incidentally, in the method of analyzing the physical property change in the vicinity of the solid-liquid interface of the present invention, since it is essential to obtain information on the change over time of the displacement of the oscillator, an analysis method using a normal atomic force microscope The step of performing feedback control, which is indispensable so that the displacement of the cantilever is stable and constant with respect to the variation in the height direction of the solid-liquid interface (direction perpendicular to the solid-liquid interface) is not included.

[2-5. Motion state analysis process]
In the motion state analysis step, the motion state of the oscillator is analyzed. The motion state analysis step can be performed by the motion state analysis unit described in “1-8. Motion state analysis unit D” in the physical property change analysis apparatus near the solid-liquid interface, and is used as a method for analyzing the motion state. Is not particularly limited as long as it is a method that can evaluate the change of the motion state caused by the change of the physical property by using the displacement information of the vibrator and / or the position information of the vibration direction.

As shown schematically in FIG. 2, when a vibrator is vibrated with a vibration amplitude of about 100 nm in a solution near the solid-liquid interface, the vibrator receives liquid resistance that depends on the physical properties (eg concentration) of the solution. For example, when the substance concentration of the liquid is the reference concentration, the deflection (displacement) of the vibrator during vibration is about the amount shown in FIG. 2A, whereas the substance concentration of the liquid is as shown in FIG. 2B. Becomes higher, the vibrator receives a higher solution resistance, so that it flexes more, and as shown in FIG. 2 (c), when the substance concentration of the liquid becomes lower, the solution resistance received by the vibrator becomes smaller. Deflection is also small.

As a more specific example, Fig. 3 shows the case where the solid-liquid interface is an electrochemical interface composed of a metal lithium / electrolyte system. As shown in FIG. 3A, when the current is zero (open circuit state), the lithium ion concentration near the solid-liquid interface is almost equal to the lithium ion concentration in the entire electrolytic solution. On the other hand, as shown in FIG. 3B, in the case of discharging (dissolution process), the lithium ion concentration near the solid-liquid interface locally rises and the oscillator receives a higher solution resistance. Bend larger. In addition, as shown in FIG. 3C, when charging (electrodeposition process), the concentration of lithium ions near the solid-liquid interface is locally reduced, and the solution resistance received by the vibrator is reduced. Also becomes smaller. This makes it possible to follow changes in the lithium ion concentration during the operation of the device having the electrical interface.

As specific methods for analyzing the motion state of the oscillator, there are vibration response analysis or energy dissipation analysis, for example.

(Vibration response analysis)
In the vibration response analysis, the vibration direction position information from the vibrator drive unit is used as the vibration amplitude information, or the vibration estimated from the displacement information of the vibrator (specifically, the size of the positional deviation of the light receiving spot of the optical lever). Using the amplitude information, the state where the vibration amplitude of the oscillator is maximum with respect to the excitation frequency (resonance state), that is, the resonance angular frequency is obtained as the information of the motion state. As described above, the motion state of the oscillator in the solution is always affected by the liquid resistance. Here, the liquid resistance includes two types, viscous resistance due to its viscosity η (Pa · s) and mass inertia resistance due to its weight density ρ (g · cm ⁻³ ). Although the magnitude of the liquid resistance actually received by the oscillator also depends on its shape, it is possible to analyze the motion state by assuming a specific shape. For example, a resonance angular frequency in a liquid (hereinafter, a solution will be described as an example) of a vibrator (hereinafter, a cantilever will be described as an example) that is forcibly excited by sinusoidal vibration is It is reported to be expressed by the following formula (1).

Here, ω ₀ is a resonance angular frequency (s ⁻¹ ) of the cantilever in vacuum, and K is an intrinsic constant determined by the shape of the cantilever. As shown in the equation (1), the resonance angular frequency in the solution changes depending on the viscosity η and the weight density ρ of the solution. It has also been reported that the viscosity and the weight density of a solution generally change depending on the concentration of the solution. Therefore, by recording the change in the resonance angular frequency of the cantilever, it becomes possible to investigate the change in the solution concentration near the solid-liquid interface.

The vibration response analysis method is a method similar to the general vibration viscosity measurement method, and is preferable in terms of simplification of the device configuration.

(Energy dissipation analysis)
In the energy dissipation analysis, the energy consumption in each cycle, that is, the energy dissipation value, is obtained as motion state information from the force curve for each cycle of the oscillator obtained from the displacement information and the vibration direction position information. When a vibrator (hereinafter, a cantilever is taken as an example and described) is periodically vibrated at a solid-liquid interface, the cantilever is divided into a process in which the cantilever approaches a solid surface and a process in which the cantilever moves away from the solid surface. Liquid (Hereinafter, a solution will be described as an example.) It receives a force depending on the resistance. It has been reported that the magnitude F of the solution drag force exerted on the cantilever in the process of such movement can be approximately expressed by the following equation (2).

Here, the coefficients A and B are constants depending on the shape of the cantilever and experimental conditions, and ω is the angular frequency of excitation. As shown in equation (2), the resistance of a solution correlates with the weight density and viscosity of the solution. Therefore, the force applied to the cantilever in the solution changes depending on the solution concentration. On the other hand, the magnitude of the resistance force also changes depending on the magnitude of the velocity (dz / dt) and acceleration (d ² z / dt ² ) of the cantilever oscillating in the vertical direction. It is usually difficult to calculate the solution concentration using the size itself. Therefore, it is possible to evaluate the change in the solution concentration by using the energy dissipation value W obtained by integrating the magnitude of the force received by the cantilever over one cycle of the vertical movement shown in the formula (3) as an index.

-Time-dependent terms are all constants by integrating in one cycle. Therefore, the energy dissipation value W depends on the viscosity η and the weight density ρ. Since these values change depending on the concentration of the solution, it is possible to investigate the change in the concentration of the solution by recording the energy dissipation value in one cycle of the cantilever.

In the energy dissipation analysis method, the energy consumption in one cycle above and below the cantilever is obtained, so one energy dissipation value can be obtained from information for one cycle of cantilever movement. Therefore, the energy dissipation analysis method is preferable because the time resolution of measurement is extremely high.

As described below, from the viewpoint of simplification of analysis, the oscillatory wave that excites the oscillator is preferably a triangular wave rather than a sine wave used in a normal atomic force microscope. When exciting the cantilever with sinusoidal vibration, both the velocity term and the acceleration term in equation (3) must be dealt with. On the other hand, when the cantilever is excited by a triangular wave, the acceleration term (d ² z / dt ² ) in equation (3) becomes zero. FIG. 4 shows a comparison of changes over time in velocity and acceleration components when excitation is performed with a sine wave and a triangular wave. In the case of sine wave excitation, only the phase change occurs, whereas in the case of triangular wave, the velocity component is constant and the acceleration component is 0. Therefore, the equation of the energy dissipation value W can be simplified as shown in the following equation (4).

C is a constant that depends on the shape of the cantilever and the measurement conditions. If these conditions do not change during the control of liquid properties near the solid-liquid interface, the energy dissipation value is proportional to the square root of the product of solution viscosity and weight density. Since the concentration of the solution is uniquely determined from the product of the viscosity and the weight density of the solution, it is possible to analyze the concentration of the solution more directly by using the equation (4). In the actual measurement, the energy dissipation measurement is performed at the solid-liquid interface in the uncontrolled state, and the device constant C on the measurement can be determined in advance from the obtained value.

(Preliminary information time series recording process)
The analysis of the motion state may be performed in real time as soon as the displacement information and / or the vibration direction position information of the vibrator is acquired, or the displacement information and / or the vibration direction position information of the vibrator may be temporarily recorded in time series as preliminary information. May be recorded in step (preliminary information time-series recording step) and the stocked preliminary information may be used to perform post-processing analysis of the exercise state. The preliminary information time-series recording step can be performed in the time-series recording section described in “1-9. Time-series recording section E” in the physical property change analysis apparatus near the solid-liquid interface.

In the method for analyzing the physical property change in the vicinity of the solid-liquid interface of the present invention, it is necessary to capture the change in the motion state of the oscillator during the control of the solid-liquid interface. Therefore, an analysis method using a normal atomic force microscope The step of correcting when the exercise state obtained in the exercise state analysis step becomes a predetermined value or more, which is indispensable for the above, is not included.

[2-6. Time-series recording process]
In the time series recording step, the control information in the physical property control step and the motion state obtained in the motion state analysis step are obtained in a time series recorded state. The time-series recording step can be performed in the time-series recording unit described in “1-9. Time-series recording unit E” in the physical property change analysis apparatus near the solid-liquid interface. Recording in time series means recording the acquired information in association with a time element. For example, the acquired information can be obtained in the form of a data set synchronized with the control history of the physical property control process. This allows a change in the exercise state to be recorded over time in a state associated with the control information that caused the change.

In the method of analyzing the physical property change in the vicinity of the solid-liquid interface of the present invention, it is necessary to capture the change in the motion state of the oscillator during the control of the solid-liquid interface. The motion state of the oscillator at a fixed position (one coordinate in the solid-liquid interface) is recorded in time series over multiple oscillations of the oscillator. The recording rate may be, for example, a level at which 50 to 2000 pieces, preferably 200 to 2000 pieces, of movement state information can be recorded per second at one coordinate in the solid-liquid interface.

In the case where the above-mentioned preliminary information time-series recording process is performed in advance, when force curve measurement is performed from displacement information and vibration direction position information for use in motion state analysis, a force curve for one vibration of the vibrator is obtained. When n points of displacement information and position information are required for measurement and a force curve is measured m times per second, n × m sets of displacement information-position information combinations per second at one coordinate are recorded as preliminary information. can do. From the preliminary information, the motion state analysis unit can obtain m motion state information per second at one coordinate, and the time series recording unit can record m motion state information per second.

[2-7. Physical property derivation process]
The method for analyzing the change in physical properties in the vicinity of the solid-liquid interface of the present invention further includes the step of deriving the actual solution physical properties from the information on the motion state of the oscillator obtained in the time series recording unit (physical property deriving step). Good. The physical property derivation step can be performed by the physical property derivation unit described in “1-10. Physical property derivation unit F” of the physical property change analysis apparatus near the solid-liquid interface. The example of the method for deriving the solution physical properties is as described above. The physical properties of the obtained solution are also recorded in time series.

[2-8. Output process]
In the method for analyzing the physical property change in the vicinity of the solid-liquid interface of the present invention, the relationship between time and motion state or the relationship between time and specific solution physical property is displayed in an arbitrary format corresponding to physical property control information. It may further include a step (output step). The output step can be performed by the output unit described in “1-11. Output unit G” of the physical property change analysis apparatus near the solid-liquid interface. An example of the output format is as described above.

[3. Analysis program for physical properties near solid-liquid interface]
The above-described method of analyzing changes in physical properties in the vicinity of the solid-liquid interface of the present invention may be realized by a program.

A program is a computer program that causes a computer to execute each procedure. Therefore, when the method of analyzing the physical property change in the vicinity of the solid-liquid interface is executed based on the program, the arithmetic unit and the control unit included in the computer execute the respective procedures, and therefore perform arithmetic and control based on the program. In addition, the storage device included in the computer stores the data used for the processing based on the program in order to execute each processing.

Also, the program can be recorded in a computer-readable recording medium and distributed. The recording medium is a medium such as a magnetic tape, a flash memory, an optical disc, a magneto-optical disc or a magnetic disc. Further, the recording medium may be an auxiliary storage device or the like. Further, the program can be distributed through a telecommunication line.

[3-1. Program 1]
A program for analyzing physical properties near a solid-liquid interface according to the present invention is a computer program for analyzing physical properties near a solid-liquid interface; a procedure for analyzing a motion state of an oscillator arranged in a liquid forming the solid-liquid interface. (S11); a program (program 1) for executing the above-mentioned motion state and a procedure (s12) of recording the above-mentioned motion state and control information relating to the control of liquid physical properties in the vicinity of the solid-liquid interface in time series. .

The physical property analysis program (program 1) near the solid-liquid interface of the present invention may be installed in the above-mentioned “1. Physical property change analysis device near solid-liquid interface”. For example, the computer that executes the program for analyzing the physical properties in the vicinity of the solid-liquid interface of the present invention may constitute a part of the above-mentioned “1. More specifically, the procedure (s11) is executed by the above “1-8. Motion state analysis unit D”, and the procedure (s12) is executed by the above “1-9. Time series recording unit E”. Can be made.

[3-2. Program 2]
In addition to the program 1, the program for analyzing the physical properties near the solid-liquid interface of the present invention is arranged in a liquid constituting the solid-liquid interface in a computer in order to analyze the physical properties near the solid-liquid interface. A step (s21) of analyzing the motion state of the oscillator moving along the solid-liquid interface; and a two-dimensional mapping image in which the position of the oscillator moving and the motion state of the oscillator at the position correspond to each other. A step (s22) of acquiring; a step (s23) of acquiring an average value of the motion state at each of predetermined moving distances equally divided from the total moving distance of the vibrator; In a time series of the movement of the oscillator (s24); and a step of recording in time series the average value of the motion state and the control information regarding the control of the liquid property near the solid-liquid interface ( s25) ; May be a program for causing the execution (program 2).

In the physical property analysis program (program 2) near the solid-liquid interface of the present invention, the above procedure (s21) and (s22) can be executed by a computer installed in the atomic force microscope. The above procedure (s23) to (s25) can be appropriately selected and executed by those skilled in the art from the arithmetic device, the control device, and the storage device included in the computer.

However, when the program 2 is executed by a computer installed in the atomic force microscope, it is necessary to use the atomic force microscope under special conditions so as not to fulfill its original purpose. For example, the automatic correction function (the function that automatically corrects the motion state of the cantilever) implemented in the atomic force microscope must not be operated, so only under conditions limited to the range where the automatic correction function does not operate. Can be run. As such a limited condition, for example, in the case of a condition for an electrochemical interface, the change in the concentration of the electrolyte determined by the product of the current density and the conduction time is the limit value at which the automatic correction of the atomic force microscope operates. Below (for example, the absolute value of the current density is 0.2 mAcm ⁻² or less).

Further, unlike the program 1 that analyzes changes in physical properties at a fixed position (1 coordinate) in the solid-liquid interface, the program 2 needs to acquire a two-dimensional mapping image once in the above procedure (s22). The recording rate must be sufficiently low in order to acquire data stably while scanning. For example, the recording rate is, for example, 2 to 9 times, preferably 2 to 4 times per second. Further, since it is necessary to obtain a two-dimensional mapping image once in the above step (s22), the electrochemical liquid reaction between solid and liquid or the catalytic reaction or the thermal change on the solid that causes the change in the physical properties of the liquid is caused by the entire solid surface. And should be as homogeneous as possible.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

[Test Example 1]
In this test example, at the model electrochemical interface of the metal lithium battery, changes in the concentration of the electrolytic solution near the electrochemical interface during the operation of the battery were measured over time.

The structure of the electrochemical interface is as follows.
Electrode: Lithium metal Electrolyte: 1M lithium bistrifluoromethanesulfonylamide (LiTFSA) in tetraglyme (G4)

The time-dependent measurement of changes in the concentration of the electrolytic solution near the electrochemical field is performed by switching the current applied to the battery in a stepwise manner (the cell voltage is determined according to the control current value) while using an atomic force microscope (iCON (Bruker). )) Was used to temporarily obtain a two-dimensional image of the energy dissipation value (FIG. 5 (a)), and then the two-dimensional image was reconstructed as a temporal recording (FIG. 5 (b)). . The details are shown below.

The measurement mode of the atomic force microscope was Peak Force Tapping (exciting the cantilever at high speed), the excitation wave was a sine wave, the force curve measurement frequency was 2 kHz, and the cantilever amplitude width was 100 nm. PeakForce Tapping is a method of recording the change in force while moving the cantilever closer to or farther from the electrode (that is, scanning the electrode surface while periodically performing force curve measurement (force curve mapping)). The atomic force microscope has a function to record the energy dissipation value for each xy coordinate data point in the force curve mapping mode. Thereby, the two-dimensional spatial information (FIG. 5A) of the energy dissipation value in one image was obtained. This two-dimensional image has 1024 × 1024 pixels (pxl), and energy dissipation values W ₁ to W _1048576 are recorded for each pixel.

On the other hand, the atomic force microscope does not have a function of recording energy dissipation values in time series. In order to carry out the method of analyzing the physical property change in the vicinity of the solid-liquid interface of the present invention, a process of reprinting the two-dimensional image recording to the time recording was intentionally performed. Specifically, first, a two-dimensional image of 1024 × 1024 pixels (FIG. 5A) was raster-scanned at a speed of 1 line / 1 Hz, that is, 1 line per second. By doing so, the change in energy dissipation value during 1024 × 1 = 1024 seconds was recorded in the direction perpendicular to the line scan direction. Since the position information of the image is not necessary to output the energy dissipation value, the energy dissipation values recorded in one line are averaged (that is, the energy dissipation data information for one second is averaged) in the process of analysis, and the line scan is performed. Similar averaging was repeated in the direction perpendicular to the direction to create a data profile. Specifically, the average value of the energy dissipation values of the first line (AVG (W ₁ to ₁₀₂₄ )) is obtained as the energy dissipation value of the first second (W _T1 ), and the same operation is performed for each raster line. Similarly repeated, to give to a mean value of the energy dissipation values for 1024 line _{(AVG (W 1047553 ~ 1048576)} ) 1024 th second energy dissipation value is (W _T1024).

The time-series data of the energy dissipation value (W (eV)) every 1 second (T (sec)) obtained by this, for 1024 seconds, was converted into the current (I (mA · cm ^-2 )) of the electrochemical measuring device. ) And the voltage (E (mV)) control history (FIG. 5B). By outputting this data set in the form of a graph, changes in the energy dissipation value accompanying the electrochemical operation were displayed (FIG. 6 described later).

When recording time series data using AFM in this way, the time resolution is limited by the raster scan speed. In this test example, while the two-dimensional scanning is inevitable due to the use of the atomic force microscope, if the scanning speed is too fast, the change in physical properties according to the present invention cannot be accurately captured, and therefore stable while performing the two-dimensional scanning. In order to obtain the data, the upper limit of the scanning speed was set to about 1 line / 2 Hz. As a result, the time resolution was intentionally limited to 0.5 seconds.

In this test example, since the analysis method of the present invention is carried out, the magnitude of the fluctuation of the current applied to the battery can change the concentration of the electrolyte near the electrochemical interface to the extent that the motion state of the cantilever changes. The size of the cantilever should be within the range that does not operate the automatic correction function (function that automatically corrects the motion state of the cantilever) mounted on the atomic force microscope. Is sufficiently small, specifically, the absolute value of the current density is limited to 0.2 mAcm ⁻² or less.

Further, in this test example, since the analysis method of the present invention was carried out by utilizing the function of the atomic force microscope, it was inevitable that the xy scan function mounted on the atomic force microscope had to be operated, and it was 500 nm. Scanning was performed in the range of × 500 nm to obtain the image in FIG. In this test example, an electrode with a homogeneous lithium reaction was used, which enables time-dependent analysis of changes in physical properties even in the scan range. However, in consideration of the fact that scanning in the xy directions disturbs the solution in the vicinity of the solid-liquid interface, in the implementation of the analysis method of the present invention, the xy scanning function implemented in the atomic force microscope is excluded from the present invention. Needless to say, it is desirable to measure at a stationary position that does not disturb the solution near the solid-liquid interface by using the physical property change analysis device near the solid-liquid interface.

Furthermore, in this test example, the data shown in FIG. 5 (a), which is not obtained by the analysis method of the present invention, is acquired in advance because the analysis method of the present invention is performed by utilizing the function of the atomic force microscope. After that, it was converted into the data shown in FIG. 5B and recorded. When the analysis method of the present invention is carried out using the physical property change analyzer near the solid-liquid interface of the present invention, the data of FIG. 5A is not acquired but the data of FIG. 6B is acquired.

Figure 6 shows the analysis results. The lower part of FIG. 6 shows the change over time of the cell voltage when the dissolution and precipitation of lithium are repeated by applying a constant current, and the upper part shows the change over time of energy dissipation in synchronization with the change over time of the cell voltage. Strictly speaking, the resistance of the solution exists under any circumstance, but in order to make the results easy to understand, in this test example, the solution resistance in the initial open circuit state (see FIG. 3 (a)) was corrected to change the energy dissipation. Was set to zero.

As shown in Fig. 6, it can be seen that the dissipation energy decreases in correlation with the start of lithium deposition. The decrease in dissipated energy indicates that the solution resistance experienced by the cantilevers was decreased. That is, it is shown that the lithium deposition reaction reduced the lithium ion concentration near the electrochemical interface (see FIG. 3C). On the contrary, when the cell voltage is raised and the dissolution of lithium is started, it is understood that the value of the dissipated energy increases, and the magnitude of the solution resistance received by the cantilever increases (see FIG. 3 (b)). ing. That is, it is shown that the lithium ion concentration near the electrochemical interface was increased by the lithium dissolution reaction.

In the upper part of Fig. 6, representative force curves at each point (open circuit state, molten state, electrodeposition state) are also shown. The force curve obtained at the maximum value of the dissipated energy waveform receives an upward force in the approach (approach), that is, the direction that moves the cantilever closer to the sample (moves downward), and moves the retract, that is, the cantilever away from the sample (upward). It can be read that a downward force is applied in the direction (moving to). This means that the cantilever is moving under solution resistance larger than that in the standard state. On the other hand, the force curve obtained at the minimum value of the dissipated energy waveform shows that the relationship between the approach and the force in the retract is the opposite of the above. This means that the solution resistance at this point is smaller than that in the standard state. In this way, changes in the physical properties of the solution are reflected in the relationship between the approach and the force curve in the retract. From the above, it was proved that the change of solution resistance (for example, the change of concentration), that is, the change of physical properties can be investigated by the analysis of energy dissipation.

Further, as shown in FIG. 6, when the control current value was changed greatly (the increase and decrease widths of the cell voltage greatly changed in a corresponding manner), the decrease amount of the cell voltage was large, that is, the lithium ion concentration decreased. It was confirmed that the greater the degree, the greater the decrease in energy dissipation value, and the greater the increase in cell voltage, that is, the greater the degree of increase in lithium ion concentration, the greater the increase in energy dissipation value. Further, it can be seen that when the current value is set to 0 (the cell voltage becomes 0 in the rest state), the energy dissipation value gradually approaches the reference value. That is, it is considered that by analyzing the speed of this transient time response, it becomes possible to directly analyze the process of ion diffusion in the vicinity of the electrode electrolyte interface.

Thus, it was confirmed that the time variation of the energy dissipation value of the cantilever and the electrochemical operation correspond very well. Therefore, it was demonstrated that by analyzing the motion state of the cantilever in time series, changes in solution resistance, that is, changes in substance concentration near the electrochemical interface can be accurately analyzed with time.

In addition, as described above, in order to carry out the analysis method of the present invention in this test example, the change in the motion state of the cantilever due to the change in the concentration of the electrolytic solution is intentionally corrected by the automatic correction function (cantilever) implemented in the atomic force microscope. The current condition was controlled so that it was within the range in which the function of automatically correcting the motion state (1) was not operated. That is, according to the analysis method of the present invention, even if the concentration change in the vicinity of the electrochemical interface is so small as not to control the automatic correction function, the change in physical properties in the vicinity of the interface can be analyzed over time. Usually, not only at the electrochemical interface, but local physical property changes occurring near various solid-liquid interfaces may be larger than the physical property changes analyzed in Test Example 1. From the results of Test Example 1, it can be easily inferred that the analysis method of the present invention can similarly analyze with time even if larger physical property changes occur near various solid-liquid interfaces.

Claims (14)

1. A vibrator A arranged in a liquid forming a solid-liquid interface,
   An exciting part B for vibrating the vibrator A;
   A physical property control unit C for controlling the physical properties of the liquid in the vicinity of the solid-liquid interface,
   A motion state analysis unit D that analyzes the motion state of the oscillator A;
   A time-series recording unit E that records the control information by the physical property control unit C and the motion state obtained by the motion state analysis unit in time series,
   An apparatus for analyzing changes in physical properties near the solid-liquid interface, including
2. The time series recording unit E further records displacement information of the vibrator A and / or vibration direction position information of the vibrator in time series,
   The physical property change analysis apparatus according to claim 1, wherein the motion state analysis unit D analyzes the motion state from the displacement information and / or the vibration direction position information.
3. It further includes a physical property deriving unit F that derives physical properties from the motion state obtained by the motion state analysis unit D, and an output unit G that outputs a temporal change of the control information in association with the temporal change of the physical property. The physical property change analysis device according to claim 1.
4. The physical property change analyzer near the solid-liquid interface according to any one of claims 1 to 3, wherein the vibrator A is a cantilever having no probe at its free end.
5. The physical property change analyzer near the solid-liquid interface according to any one of claims 1 to 4, wherein the vibrator A does not have a through hole penetrating in the vibration direction.
6. The physical property change analyzer near the solid-liquid interface according to any one of claims 1 to 5, further comprising a cell accommodating the solid-liquid interface.
7. 7. The physical property change analyzer near the solid-liquid interface according to any one of claims 1 to 6, wherein the solid-liquid interface is an electrochemical interface, and the control information is current and voltage information.
8. An exciting step of vibrating a vibrator arranged in a liquid forming a solid-liquid interface,
   A physical property control step of controlling the liquid physical properties in the vicinity of the solid-liquid interface,
   A motion state analysis step of analyzing the motion state of the oscillator;
   A time-series recording step of obtaining control information in the physical property control step and the motion state obtained in the motion state analysis step in a state recorded in time series,
   A method for analyzing changes in physical properties near the solid-liquid interface, including.
9. Further comprising a preliminary information time series recording step of recording displacement information of the vibrator and / or vibration direction position information of the vibrator in time series,
   The physical property change in the vicinity of the solid-liquid interface according to claim 8, wherein in the motion state analysis step, the motion state is analyzed from the displacement information and / or the vibration direction position information recorded in the preliminary information time series recording step. How to parse.
10. The method for analyzing changes in physical properties in the vicinity of a solid-liquid interface according to claim 8 or 9, wherein the motion state is obtained as an energy dissipation value or a resonance angular frequency in the motion information analysis step.
11. The method for analyzing changes in physical properties in the vicinity of a solid-liquid interface according to any one of claims 8 to 10, wherein the oscillator is vibrated in a triangular wave.
12. The method for analyzing changes in physical properties near a solid-liquid interface according to any one of claims 8 to 11, wherein the solid-liquid interface is an electrochemical interface, and the control information is current and voltage information.
13. In order to analyze the physical properties near the solid-liquid interface, the computer
    A procedure for analyzing the motion state of an oscillator arranged in a liquid that forms a solid-liquid interface,
    A procedure for recording the motion state and control information relating to control of liquid physical properties in the vicinity of the solid-liquid interface in time series,
    A program for analyzing the physical properties near the solid-liquid interface for executing
14. In order to analyze the physical properties near the solid-liquid interface, the computer
    A step of analyzing a motion state of an oscillator arranged in a liquid forming a solid-liquid interface and moving along the solid-liquid interface;
    A step of obtaining a two-dimensional mapping image in which the position of the moving oscillator and the motion state of the oscillator at the position correspond to each other;
    A procedure of obtaining an average value of the motion state at each of predetermined moving distances equally divided from the total moving distance of the oscillator;
    A procedure of converting each of the average values of the motion state into a time series of movement of the oscillator,
    A procedure of recording the average value of the motion state and control information regarding control of liquid physical properties near the solid-liquid interface in time series,
    A program for analyzing the physical properties near the solid-liquid interface for executing

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