JP2009052893A - Solution characteristic measuring instrument and solution characteristic measuring method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solution characteristic measuring instrument and a solution characteristic measuring method, capable of outputting a measured result of reduced error, while calculating accurately a reference value. <P>SOLUTION: A driving mechanism 70 arranges selectively one sample container out of the first sample container and the plurality of second sample containers, on a propagation route of a terahertz wave T1 from an emitter unit 28, by driving a sample block 72. An antenna unit 58 receives a terahertz wave T2 after transmitted through the sample container. The first sample container stores a sample, and the plurality of second sample containers store solvents. Cell gaps of the plurality of second sample containers are formed to make thicknesses thereof different each other along the propagation route of the terahertz wave T1. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a solution characteristic measuring apparatus and a solution characteristic measuring method for measuring a characteristic of a solution, and more particularly to a technique for measuring an optical characteristic of a solution using a terahertz wave.

  In recent years, various technologies applying terahertz waves have been proposed due to advances in quantum electronics and the semiconductor industry. Terahertz waves are electromagnetic waves having a frequency of about 0.1 to 10 THz (wavelength is 3 μm to 300 μm). As an example of application of such terahertz waves, a technique for measuring the optical characteristics of a solution has been proposed.

  The absorption spectrum in the far-infrared region (terahertz region) where terahertz waves exist reflects low-energy interactions such as vibrational states between atoms and intermolecular interactions (typically van der Waals forces). . By measuring the properties of the solution in the terahertz region, it becomes possible to analyze the structure of the polymer over time. However, in general, water has a large absorption peak in the terahertz region. Therefore, when measuring the spectrum in the terahertz region for a solution (aqueous solution) in which the sample (solute) to be measured is dissolved in water, use the same technique as in the ultraviolet region and visible region where there is little water absorption. Is difficult.

For example, Non-Patent Document 1 discloses a method in which terahertz waves are transmitted through a target solution and the characteristics of the solution are spectroscopically measured. According to such a transmission-type spectroscopic measurement method, a reference value (reference spectrum) is acquired in advance, and the absorbance or transmittance of the terahertz wave with respect to the solution is calculated based on this reference value.
Jing Xu, Kevin W. Plaxco and S. James Allen, "Probing the collective vibrational dynamics of a protein in liquid water by terahertz absorption spectroscopy", Protein Science, 2006 15, 1175-1181.

  In general, in the infrared region and the visible region, the absorbance of a solute is higher than that of a solvent, and the concentration of the solute in the solution is not so high. Therefore, the reference value can be obtained in a state of only a solvent not containing a solute (for example, only water). That is, since the transmittance decreases as the concentration of the solute with respect to the solution is increased, the characteristic value for the target solution can be calculated based on the reference value.

  On the other hand, in the terahertz region, the absorbance of the solute is often lower than that of the solvent. Therefore, the transmittance increases as the concentration of the solute in the solution is increased. As a result, there is a problem that the characteristic value cannot be accurately calculated by using the reference value acquired by the conventional method.

  In the above-mentioned Non-Patent Document 1, the sample solution is put in a high-density polyethylene bag that transmits terahertz waves, the polyethylene bag is sandwiched between two parallel windows, and the distance between the parallel windows is measured. A method for measuring absorbance while adjusting (path length) is disclosed.

  However, in the method disclosed in Non-Patent Document 1, it is necessary to accurately adjust the parallel window while holding the polyethylene bag containing the solution, and there is an error generation factor between the parallel window and the polyethylene bag. It is also necessary to prevent the formation of a certain air layer. Therefore, the measurement requires a lot of labor and time, and it is difficult to automate the measurement.

Further, Non-Patent Document 1 describes that the change in absorbance is calculated based on the value I _reference as the reference value, but no method for measuring this reference value is disclosed. Further, there is no disclosure as to whether or not the reference value is determined in consideration of the thickness of the polyethylene bag. Actually, since the polyethylene bag has a finite thickness, the substantial propagation path length of the terahertz wave increases / decreases by this thickness, which may cause an error in the measurement result.

  The present invention has been made to solve such problems, and its purpose is to output a measurement result with less error after calculating a reference value (reference value) more accurately. It is to provide a solution characteristic measuring apparatus and a solution characteristic measuring method capable of performing the above.

  According to one aspect of the present invention, there is provided a solution property measuring apparatus for measuring properties of a solution comprising a solvent and a solute. The solution characteristic measuring apparatus includes a terahertz generation source that generates a terahertz wave, a first sample container and a plurality of second sample containers, a sample stage, a drive mechanism, a reception unit, a signal processing unit, and a calculation unit. Including. Each of the first sample container and the plurality of second sample containers is formed with a storage portion for storing a liquid. The sample stage holds a first sample container and a plurality of second sample containers. The drive mechanism selectively arranges one sample container among the first sample container and the plurality of second sample containers on the propagation path of the terahertz wave from the terahertz generation source by driving the sample stage. The receiving unit receives the terahertz wave after passing through the sample container. The signal processing unit outputs an intensity signal indicating the intensity of the terahertz wave received by the receiving unit. The calculation unit calculates the characteristics of the solution based on the intensity signal from the signal processing unit. The first sample container accommodates the solution, the plurality of second sample containers accommodate the solvent, and the accommodating portions of the plurality of second sample containers are formed to have different thicknesses along the terahertz wave propagation path. Has been. The computing unit includes: means for calculating a reference value based on the intensity signal for each of the plurality of second sample containers; means for calculating a characteristic regarding the solvent based on the reference value; a characteristic regarding the solvent and the first sample Means for calculating a solute-related characteristic based on an intensity signal for the container.

  Preferably, the means for calculating the reference value calculates the reference value based on a correspondence relationship between the thickness of the accommodating portion and the value of the intensity signal in each of the plurality of second sample containers.

  Preferably, each of the first sample container and the plurality of second sample containers includes a concave portion opened on the upper side in the gravity direction and a lid portion stacked on the upper side in the gravity direction of the concave portion. The terahertz wave from the terahertz source is incident on the target sample container along the direction of gravity.

  More preferably, the sample stage selects the sample container disposed on the propagation path of the terahertz wave by rotating the first sample container and the plurality of second sample containers with respect to the horizontal plane.

  According to another aspect of the present invention, there is provided a solution property measuring method for measuring properties of a solution composed of a solvent and a solute using a measuring device. The measurement apparatus includes a terahertz generation source that generates a terahertz wave, a first sample container and a plurality of second sample containers, a sample stage, a receiving unit, and a signal processing unit. Each of the first sample container and the plurality of second sample containers is formed with a storage portion for storing a liquid. The sample stage holds the first sample container and the plurality of second sample containers, and one sample container of the first sample container and the plurality of second sample containers on the propagation path of the terahertz wave from the terahertz source. Are configured to be movable so as to be selectively arranged. The receiving unit receives the terahertz wave after passing through the sample container. The signal processing unit outputs an intensity signal indicating the intensity of the terahertz wave received by the receiving unit. The first sample container accommodates the solution, the plurality of second sample containers accommodate the solvent, and the accommodating portions of the plurality of second sample containers are formed to have different thicknesses along the terahertz wave propagation path. Has been. The solution characteristic measuring method includes a step of sequentially moving the sample stage to obtain an intensity signal for each of the first sample container and the plurality of second sample containers, and an intensity signal for each of the plurality of second sample containers. A step of calculating a reference value, a step of calculating a property related to the solvent based on the reference value, a step of calculating a property related to the solute based on the property related to the solvent and the intensity signal about the first sample container; including.

  According to the present invention, it is possible to output a measurement result with less error after calculating a reference value (reference value) more accurately.

  Embodiments of the present invention will be described in detail with reference to the drawings. Note that the same or corresponding parts in the drawings are denoted by the same reference numerals and description thereof will not be repeated.

(overall structure)
FIG. 1 is a schematic configuration diagram of a solution property measuring apparatus 100 according to an embodiment of the present invention.

  A solution property measuring apparatus 100 (hereinafter also referred to as “measuring apparatus 100”) according to an embodiment of the present invention uses a terahertz time domain spectrum analysis (THZ-TDS) to generate an arbitrary solute. The characteristics of a solution dissolved in a solvent such as water at a predetermined mass% concentration are measured. In particular, measuring apparatus 100 according to the present embodiment employs transmission-type time domain spectroscopy that irradiates a target solution with terahertz waves and calculates the characteristics based on the terahertz waves that have passed through the solution. . Hereinafter, a configuration for measuring the optical characteristic values (for example, solute transmittance, absorbance, molecular extinction coefficient, etc.) of the solution in the terahertz region will be described.

  Referring to FIG. 1, measuring apparatus 100 includes an arithmetic device 2, a signal processing unit 12, an oscillator 14, a laser light source 20, a bandpass filter 22, a λ / 2 wavelength plate 24, a beam splitter 26, and the like. , Emitter unit 28, off-axis parabolic mirrors 30a, 30b, 60a, 60b, antenna unit 58, mirrors 40, 42, 44, 46, 48, 54, 56, sample exchange mechanism 70, and delay stage. 50 and a delay stage driving mechanism 52.

  In measurement apparatus 100 according to the present embodiment, at least one sample container for storing a solution to be measured (hereinafter also referred to as “sample”) and a plurality of sample containers for storing only a solvent are arranged in sample exchange mechanism 70. At the same time, the transmission intensity of the terahertz wave with respect to each sample container is sequentially acquired by driving the sample exchange mechanism 70. Based on these transmitted intensities, the optical properties of the sample are measured.

First, a configuration related to generation and reception of terahertz waves will be described.
The laser light source 20 generates a pulse laser L1 for driving an emitter unit 28 and an antenna unit 58 which will be described later. More specifically, the laser light source 20 generates and irradiates a pulsed laser L1 having a pulse width on the order of femtoseconds ( ^10-15 seconds). The oscillation period of the pulse laser L1 in the laser light source 20 is on the order of several tens of MHz (several tens of seconds).

  The band pass filter 22 transmits a specific wavelength component among the wavelengths included in the pulse laser L <b> 1 generated from the laser light source 20. As an example, when the laser light source 20 generates two kinds of pulse lasers of 1.56 μm and 0.78 μm, the bandpass filter 22 transmits a wavelength component of 0.78 μm while a wavelength of 1.56 μm. Reflects or absorbs components.

  The λ / 2 wavelength plate 24 adjusts the linearly polarized light of the pulse laser L1 after passing through the bandpass filter 22 in an arbitrary direction. Then, the pulse laser L 1 that has passed through the λ / 2 wavelength plate 24 enters the beam splitter 26. The λ / 2 wavelength plate 24 emits a pulsed laser beam of parallel rays.

  The beam splitter 26 distributes the pulse laser L1 from the λ / 2 wavelength plate 24 to the two pulse lasers L2 and L3 at a predetermined ratio, and guides them to the emitter unit 28 and the mirror 40, respectively. Here, the pulse laser L2 is used as pump light for exciting the emitter unit 28, and the pulse laser L2 is used as probe light for exciting the antenna unit 58.

  The emitter unit 28 is a terahertz wave generation source that receives the pulse laser L2 and generates a terahertz wave T1. Specifically, the emitter unit 28 includes a converging lens 28a, a photoconductive switch 28b, and a Si lens 28c. The converging lens 28a converges the pulse laser L2 from the beam splitter 26 to a predetermined position of the photoconductive switch 28b. The photoconductive switch 28b is excited by the pulse laser L2 and generates a pulsed terahertz wave T1. More specifically, the photoconductive switch 28b includes a parallel wire line formed on a substrate and a minute dipole antenna formed on a part of the parallel wire line. A predetermined AC bias voltage is applied from the oscillator 14. Then, when the pulse laser L2 enters the portion of the minute dipole antenna, a predetermined electric field is generated and a terahertz wave is generated. That is, the pulse laser L2 incident on the photoconductive switch 28b becomes pump light, and a terahertz wave T1 is generated. In addition, a predetermined AC bias voltage supplied from the oscillator 14 is generated energy of the terahertz wave T1. As an example, the photoconductive switch 28b is configured by an LTGaAs photoconductive switch in which a GaAs epitaxial film is grown at a low temperature on a GaAs substrate. The Si lens 28c diffuses the terahertz wave T1 irradiated from the photoconductive switch 28b.

The off-axis parabolic mirrors 30 a and 30 b guide the terahertz wave T 1 radiated from the emitter unit 28 to a predetermined position of the sample exchange mechanism 70. More specifically,
The terahertz wave T1 radiated from the emitter unit 28 propagates in the horizontal direction (direction orthogonal to the direction of gravity) and enters the off-axis parabolic mirror 30a. The terahertz wave T1 is incident on the off-axis parabolic mirror 30b after the propagation direction is changed to a right angle by the off-axis parabolic mirror 30a. Further, the propagation direction of the terahertz wave T1 is changed to the direction of gravity by the off-axis parabolic mirror 30b. At this time, the off-axis parabolic mirror 30 b collects the terahertz wave T <b> 1 at a specific position of the sample exchange mechanism 70. Any sample container is disposed at the condensing position (focal position) of the terahertz wave T1.

  The sample exchange mechanism 70 includes a sample base 72 configured to be rotatable, and a drive mechanism 74 that rotationally drives the sample base 72. The sample stage 72 holds a plurality of sample containers 78, and the drive mechanism 74 rotationally drives the sample stage 72 to selectively place one of the plurality of sample containers 78 at the focal position of the terahertz wave T1. To do. As will be described later, each sample container 78 contains the same solvent as the sample or the solvent contained in the sample.

  The sample stage 72 has an opening at a position where each sample container 78 is held, and the terahertz wave T1 from the off-axis paraboloid mirror 30b propagates in the direction of gravity so that one side of the sample stage 72 is provided. Is incident on one of the sample containers 78, passes through the sample container 78, and is emitted from the other surface side of the sample table 72. That is, the terahertz wave T <b> 2 that has passed through the sample container 78 is in a state of being absorbed according to the characteristics of the sample or solvent contained in the sample container 78. The drive mechanism 74 drives the sample stage 72 in accordance with a control signal CTRL1 from the arithmetic device 2 described later.

FIG. 2 is an external view of sample exchanging mechanism 70 according to the embodiment of the present invention.
With reference to FIG. 2, as an example, seven cutouts 73 are formed on the outer peripheral side of the sample base 72, and through holes 73 a are formed on the bottom surface of each cutout 73. Each notch 73 is configured such that a sample container 78 can be inserted therein, and a presser plate 72a is provided on the upper portion thereof. The holding plate 72a fixes the sample container 78 inserted into the target cutout 73.

  The sample table 72 is rotatably supported by a drive mechanism 74. The drive mechanism 74 includes a rotation support portion 74a composed of a plurality of gears and the like, and a motor 74b that drives the rotation support portion 74a. The motor 74b is rotationally driven in accordance with the control signal CTRL1 (FIG. 1) from the arithmetic unit 2, so that the rotation support portion 74a rotates the sample stage 72 by this driving force.

  As described above, the sample stage 72 holding the plurality of sample containers 78 rotates, so that one sample container 78 is selectively disposed on the propagation path of the terahertz wave.

  Since the terahertz wave is easily affected by the water vapor component in the air, it is preferable that the predetermined area including the sample exchange mechanism 70 is subjected to pressure reduction or nitrogen substitution before measurement.

  Referring to FIG. 1 again, the terahertz wave T2 transmitted through the sample container 78 is sequentially reflected by the off-axis paraboloid mirrors 60a and 60b and guided to the antenna unit 58. Specifically, the propagation direction of the terahertz wave T2 after passing through the sample container 78 is changed in the horizontal direction by the off-axis parabolic mirror 60b. Further, the terahertz wave T2 is incident on the antenna unit 58 after the propagation direction is bent at a right angle by the off-axis parabolic mirror 60a. At this time, the off-axis parabolic mirror 60 a condenses the terahertz wave T <b> 2 at the light receiving position of the antenna unit 58.

  The antenna unit 58 receives the terahertz wave T2 from the off-axis parabolic mirror 60a, and outputs a measurement signal corresponding to the intensity of the received terahertz wave T2 to the signal processing unit 12. The antenna unit 58 receives the pulse laser L3 separated by the beam splitter 26 as an energy source for generating a measurement signal. That is, the antenna unit 58 can output a measurement signal at a timing when both the terahertz wave T2 from the off-axis parabolic mirror 60a and the pulse laser L3 from the beam splitter 26 are incident.

  The antenna unit 58 includes a converging lens 58a, a photoconductive switch 58b, and a Si lens 58c. The Si lens 58c has the same configuration as the Si lens 28c in the emitter unit 28 described above, and converges the terahertz wave T2 from the off-axis paraboloidal mirror 60a. The converging lens 58a converges the pulse laser L3 from the beam splitter 26 to a predetermined position of the photoconductive switch 58b. The photoconductive switch 58b has the same configuration as the photoconductive switch 28b in the emitter unit 28 described above, and receives a terahertz wave T2 on one side and a pulse laser L3 on the other side, thereby measuring an electrical signal. Output a signal.

  This measurement signal is essentially a value corresponding to the product of the intensity of the terahertz wave T2 and the intensity of the pulse laser L3, but since the intensity of the pulse laser L3 can be considered to be constant over time, the measurement signal Substantially indicates the intensity of the terahertz wave T2. Thus, the measurement signal includes information about the characteristics of the liquid (solution or solvent) contained in the sample container 78.

  In the present embodiment, the example in which the emitter unit 28 and the antenna unit 58 are configured by the photoconductive switches 28b and 58b has been described. However, if the device generates a conversion action between an electric signal and a terahertz wave, It is not limited to these. Instead of these, for example, a photoconductive switch made of InAs or InSb may be used, or an electro-optic (EO) crystal may be used. As typical examples of electro-optic crystals, organic nonlinear optical crystals such as 4-dimethylamino-N-methyl-4-stilbazolium tosylate (DAST) are known. The antenna unit 58 may be a bolometer that is a thermal light intensity detector.

  The pulse laser L3 distributed by the beam splitter 26 is sequentially propagated through the mirrors 40, 42, 44, 46, 48, 54, and 56 and guided to the antenna unit 58. The mirrors 42 and 44 on the propagation path of the pulse laser L3 are arranged in the delay stage 50. The delay stage 50 is configured to be movable in the vertical direction on the paper surface by the delay stage driving mechanism 52, and the positions of the mirrors 42 and 44 change in the vertical direction on the paper surface by the movement of the delay stage 50. Note that the delay stage drive mechanism 52 moves the delay stage 50 at a predetermined speed in accordance with a control signal CTRL2 from the arithmetic unit 2 described later.

The delay stage 50 and the delay stage drive mechanism 52 are configured to more easily measure the intensity waveform on the time axis of the terahertz wave T2 received by the antenna unit 58. That is, since the pulse width of the pulse laser L2 is on the order of femto (10 ⁻¹⁵ ) seconds, it is very difficult to measure the time waveform as it is. Therefore, the entire time waveform is measured by combining the terahertz waves T2 obtained by measuring the intensity of the terahertz wave T2 over a plurality of times on the time axis.

  As described above, since the antenna unit 58 outputs the measurement signal at the timing when both the terahertz wave T2 and the pulse laser L3 are incident, the predetermined phase of the terahertz wave T2 is shifted by shifting the phase of the pulse laser L3 with respect to the terahertz wave T2. The strength at can be measured.

  That is, when the delay stage 50 moves on the paper surface or in the downward direction at a predetermined speed, the positions of the mirrors 42 and 44 are changed, whereby the propagation path length of the pulse laser L3 from the beam splitter 26 to the antenna unit 58 is changed over time. Changes. A time difference (delay time) between the timing at which the terahertz wave T2 generated by the pulse laser L2 enters the antenna unit 58 and the timing at which the pulse laser L3 enters the antenna unit 58 according to the position change of the delay stage 50. Changes over time.

FIG. 3 is a diagram for explaining an outline of a method for measuring a time waveform of a terahertz wave.
FIG. 3A shows a time waveform of the terahertz wave to be synthesized, and FIG. 3B shows a time waveform of the terahertz wave T2 and the pulse laser L3 to be implemented.

Referring to FIG. 3B, since the pulse width of the terahertz wave T2 is generally longer than the pulse width of the pulse laser L3 (on the order of ^10-15 seconds), the phase of the pulse laser L3 is changed for each period. By sequentially shifting to t, the intensity of the terahertz wave T2 at a specific timing of the terahertz wave T2 can be measured.

  As described above, when the delay stage 50 moves at a predetermined constant speed, the propagation path length of the pulse laser L3 changes with time. Further, since the terahertz wave T2 and the pulse laser L3 are generated in a common cycle, the phase of the pulse laser L3 with respect to the terahertz wave T2 in each cycle changes at a predetermined speed.

As a more specific example, consider a case where the laser light source 20 generates a pulse laser L1 at an oscillation frequency of 50 MHz (oscillation period 20 nsec) and the delay stage 50 moves at 1 mm / sec. By the movement of the delay stage 50, the propagation path length of the pulse laser L2 changes at 2 × 1 mm / second. Note that the pulse laser L3 reciprocates in the delay stage. Here, assuming that the measurement cycle (time interval between adjacent measurement points) is 1 msec (1 × 10 ⁻³ seconds), the phase of the pulse laser L3 with respect to the terahertz wave T2 is determined between a certain measurement point and the measurement point following this. The time is shifted by ^20/3 × 10 ⁻¹⁵ seconds (= 2 × 1 × 10 ⁻³ m / second × 1 × 10 ⁻³ second / 3 × 10 ⁸ m / second). “3 × 10 ⁸ m / sec” is the speed of light. Therefore, in this case, it means that the terahertz wave T2 can be sampled and measured at intervals of ^20/3 × 10 ⁻¹⁵ seconds.

  As shown in FIG. 3B, at each measurement time t2 to t12, the phase of the pulse laser L3 with respect to the terahertz wave T2 changes by a predetermined phase between adjacent periods. Therefore, each measurement time t2 to t12, By plotting the relationship between the intensity values M2 to M12 of the terahertz waves corresponding to the measurement times t2 to t12, the time of the terahertz wave T2 with its time axis extended as shown in FIG. Waveform can be acquired.

  In FIGS. 3A and 3B, measurement points and measurement times are omitted for the sake of simplicity.

  Based on the principle as described above, the time waveform of the terahertz wave T2 is measured. Since the measured time waveform is obtained by extending the time axis, various processes are executed after correcting the time axis to real time in an arithmetic process such as Fourier transform described later. .

  Referring to FIG. 1 again, the oscillator 14 generates a reference signal for modulating the terahertz wave generated by the emitter unit 28. Typically, the oscillator 14 generates a sine wave having a predetermined period (for example, several tens of kHz). As described above, a part of this reference signal is used as a bias voltage for the photoconductive switch 28b constituting the emitter unit 28. Due to this bias voltage, the intensity of the terahertz wave T1 has a temporal periodic component. On the other hand, the signal processing unit 12 extracts a component corresponding to the periodic component of the reference signal from the measurement signal output from the antenna unit 58 based on the reference signal from the oscillator 14, and the temporal intensity of the terahertz wave. Is output as an intensity signal.

  In this way, by performing the measurement using the temporally modulated terahertz wave T1, it is possible to suppress the influence of noise components that enter during the terahertz wave measurement process and propagation process.

FIG. 4 is a block diagram illustrating a schematic functional configuration in the signal processing unit 12.
Referring to FIG. 4, signal processing unit 12 typically includes a lock-in amplifier, and includes a multiplier 121 and a low-pass filter (LPF) 122. The multiplier 121 multiplies the measurement signal from the antenna unit 58 and the reference signal from the oscillator 14 to generate a multiplication signal. Then, the low-pass filter 122 extracts only a component below a predetermined frequency band from the multiplication signal and outputs it as an intensity signal.

  That is, the multiplier 121 multiplies the measurement signal from the antenna unit 58 by the reference signal to separate the component indicating the characteristics of the sample included in the measurement signal and the noise component in terms of frequency. And the low-pass filter 122 can output only the component indicating the characteristics of the sample by blocking the noise component among the components separated in terms of frequency.

  Referring to FIG. 1 again, arithmetic unit 2 outputs control signal CTRL1 for controlling drive mechanism 74 of sample exchange mechanism 70 and control signal CTRL2 for controlling delay stage drive mechanism 52, Based on the intensity signal output from the processing unit 12, the optical characteristics of the sample are calculated.

  FIG. 5 is a schematic diagram showing a schematic hardware configuration of arithmetic device 2 according to the embodiment of the present invention.

  Referring to FIG. 5, arithmetic device 2 is typically implemented by a computer, and executes a program (Central Processing Unit) 200 that executes various programs including an operating system (OS), and the CPU 200 executes the program. A memory unit 212 that temporarily stores data necessary for storage, and a hard disk unit (HDD: Hard Disk Drive) 210 that stores a program executed by the CPU 200 in a nonvolatile manner. The hard disk unit 210 stores a program for realizing processing as will be described later, and such a program is stored in the flexible disk 216a or the CD-ROM by the FDD drive 216 or the CD-ROM drive 214, respectively. It is read from a ROM (Compact Disk-Read Only Memory) 214a or the like.

  The CPU 200 receives an instruction from a user or the like via the input unit 208 including a keyboard and a mouse, and outputs a measurement result measured by executing the program to the display unit 204. In addition, the CPU 200 performs data communication with the signal processing unit 12, the drive mechanism 74, the delay stage drive mechanism 52, and the like via the interface unit 206.

(Measuring method)
Next, the measurement principle in measuring apparatus 100 according to the present embodiment will be described.

  In absorption spectrum measurement, which is a general transmission-type solution measurement, a value measured in a solvent-only state (for example, only water) is adopted as a reference value, and the transmittance and absorbance are calculated from changes to this reference value. calculate. In this case, the following Lambert-Beer rule can be applied.

log ₁₀ (I ₀ / I) = ε · c · l (1)
Where I ₀ is the reference intensity, I is the transmitted light intensity, ε is the molecular extinction coefficient (l / mol / cm) of the solvent, c is the molar concentration of the solvent (mol / l), and l is the optical path length (cm). .

In order to suppress the influence of the sample container scattering (measuring cell) and the solvent, reference intensity I _0, the value of the sample container were measured in a state filled with the solvent alone are employed. The transmitted light intensity I is a value measured using the same sample container as that used for measuring the reference value. Here, since the optical path length l can be measured in advance, if either one of the molecular extinction coefficient ε and the molar concentration c of the solvent is known, the molecular absorption of the solvent is determined from the reference intensity I ₀ and the transmitted light intensity I. The coefficient ε or the molar concentration c can be calculated.

  In general, in the infrared region and the visible region, the absorbance of a solute is higher than that of a solvent, and the concentration of the solute in the solution is not so high. On the other hand, in the terahertz region (far infrared region), the absorbance of solutes is often lower than that of solvents. Therefore, when measuring a solution with a low concentration, there is a problem that the measurement accuracy cannot be increased because the change that occurs is relatively small with respect to the reference value measured in a state where the sample container is filled with only the solvent. is there.

Further, when the concentration of the solution is high, the transmittance increases due to a decrease in the ratio of the medium to the solution. As a result, the term (I ₀ / I) in the left side of the equation (1) becomes smaller than 1, and the equation (1) may not be established.

  Therefore, in the solution characteristic measurement method according to the present embodiment, a plurality of sample containers having different terahertz wave propagation path lengths are prepared, and a reference value is calculated from values measured in a state where each sample container is filled with only a solvent. To do.

  FIG. 6 is an external view of sample containers 78-1 to 78-N for calculating reference values according to the embodiment of the present invention. FIG. 6 schematically shows the characteristic configuration of the sample container, and does not represent actual dimensions as they are.

  Referring to FIG. 6, the sample container 78-1 includes a recess 781b that opens upward in the gravitational direction, and a lid 781a that is stacked on the upper side of the recess 781b in the gravitational direction. A solvent for calculating the reference value is accommodated in the space between the concave portion 781b and the lid portion 781a. That is, these spaces form a storage portion 781c for storing the solvent. The lid 781a and the recess 781b are pressed against each other with a screw (not shown) in the vertical direction. Similarly, the sample containers 78-2 to 78-N are composed of concave portions 782b to 78Nb and lid portions 782a to 78Na, respectively.

  In addition, the recesses 781b to 78Nb and the lid portions 781a to 78Na are all typically made of quartz glass. Note that the recesses 781b to 78Nb may be formed by digging a columnar glass member into a columnar glass member, or by welding or bonding a donut-shaped glass member to the columnar glass member. May be.

In particular, the depths (hereinafter also referred to as “cell gaps”) d _{1 to} d _n of the openings in the recesses 781 b to 78 Nb are configured to be different from each other. As an example, the cell gap _d 1 to d _n of the sample container 78-1~78-N is 20 [mu] m, 40 [mu] m, 60 [mu] m, 80 [mu] m, is set such as 100 [mu] m, also the diameter is set to about 5 to 30 mm.

  Since each of the sample containers 78-1 to 78 -N is horizontally disposed on the cutout portion 73 (FIG. 2) of the sample table 72, the terahertz wave propagates through the target sample container in the vertical direction on the paper surface. Therefore, the cell gap of each sample container corresponds to the path length through which the terahertz wave propagates through the solvent.

Using the transmitted light intensity I _{i: i = 1 to N} (intensity signal output from the signal processing unit 12) measured for each of the sample containers 78-1 to 78 -N filled only with the solvent, the reference value is calculated. The calculation procedure will be described later.

  On the other hand, the sample whose characteristics are to be measured is accommodated in a sample container having the same size and material as the sample containers 78-1 to 78-N.

  FIG. 7 is an external view of sample container 78-A for containing the solution according to the embodiment of the present invention.

Referring to FIG. 7, sample container 78-A is similar to sample containers 78-1 to 78-N described above, and has a recess 78Ab opened on the upper side in the gravity direction and a lid stacked on the upper side in the gravity direction of the recess 78Ab. Part 78Aa. The cell gap d _k formed in the recess 78Ab can be set to any value as long as it is known.

In the solution characteristic measurement method according to the present embodiment, the transmitted light intensity I _t (the intensity signal output from the signal processing unit 12) is measured in a state where the sample container 78-A is filled with the sample to be measured, and is calculated in advance. that with reference to the reference value, the transmitted light intensity I _t is the measured, measuring the optical properties of the sample. FIG. 7 typically shows only one sample container for containing a sample, but there is no limitation on the number. That is, once the reference value is calculated, the optical characteristics of various samples can be calculated continuously as long as the same sample container is used.

(I) Method for Evaluating Molecular Absorption Coefficient First, as an example of the optical characteristics of the sample, a case where the molecular extinction coefficient of a solute present in the sample is evaluated will be described.

Spectra obtained by Fourier transforming the intensity signals (time domain signals) measured for the sample containers 78-1 to 78-N filled with the solvent are respectively T ₁ (f), T ₂ (f), ..., T _N (f). Further, a spectrum when the cell gap is zero, that is, when no solvent is present in the sample container is used as a reference value. Hereinafter, this reference value is referred to as a reference spectrum T ₀ (f).

In the solution characteristic measurement method according to the present embodiment, the reference spectrum T ₀ (f) is calculated based on the spectra T ₁ (f), T ₂ (f),..., T _N (f). Hereinafter, the case where the solvent is water will be described.

When the Lambert-Beer rule is applied as in the above equation (1), the following equation (2) is established.
log ₁₀ (T ₀ (f) / T _i (f)) = ε (f) · c _{H 2 O} · d _i (2)
When this equation (2) is modified, equation (3) is obtained.

log ₁₀ T _i (f) = log ₁₀ T ₀ (f) −ε (f) · c _{H 2 O} · d _i (3)
However, 1 ≦ i ≦ N, and c _H2O is the H ₂ O concentration of pure water (= 1000/18 = 55.5 mol / l).

Here, if the sample container is filled only with the solvent (water), the molecular extinction coefficient ε (f) · c _{H 2 O} of the solvent becomes a constant value A. When this constant value A is used to transform equation (3), equation (3 ′) is obtained.

log ₁₀ T _i (f) = − A · d _i + log ₁₀ T ₀ (f) (3 ′)
From this equation (3 ′), it can be seen that the change of log ₁₀ T _i (f) with respect to the cell gap d _i is a linear function, and its intercept is log ₁₀ T ₀ (f). That is, the spectrum T ₀ (f) measured from the sample containers 78-1 to 78 -N filled only with the solvent and the corresponding cell gap d _i are plotted, and the value of the intercept expressed by interpolating this plot Can be calculated as log ₁₀ T ₀ (f).

Further, let T _t (f) be a spectrum obtained by Fourier transforming the intensity signal (time domain signal) measured for the sample container 78-A filled with the sample.

Here, the case where the sample accommodated in sample container 78-A contains the solute of (100- _Ak ) mass% concentration (w / w) is considered. At this time, the sample, it means that contains solvent (water) of A _k wt% concentration (w / w), the spectrum T _ak of the transmitted light intensity of theoretical from the solvent _(f) Can be expressed as:

_{log 10 T ak (f) =} log 10 T 0 (f) -ε (f) · c H2O · (A k / 100) d k ··· (4)
As described above, since log ₁₀ T ₀ (f) can be calculated in advance based on the measurement results for the sample containers 78-1 to 78 -N, the sample container 78 -A (cell gap d _k and solute concentration (100− Log ₁₀ T _ak (f) in (A _k ) mass% concentration) can be calculated.

Further, the spectrum T _s (f) of the terahertz wave absorbed in the solute is _equal to the spectrum T _t (f) measured for the sample container 78-A filled with the sample and the theoretical transmission derived from the solvent. Using the light intensity spectrum T _ak (f), it can be expressed as follows.

T _s (f) = T _ak (f) −T _t (f) (5)
When the Lambert-Beer rule is applied to this equation (5) as in the above equation (1), the following equation is established.

log ₁₀ T _s (f) = log ₁₀ (T _ak (f) / T _t (f)) = ε _s (f) · c _s · d _k (6)
Where c _s (f) is the molar concentration (mol / l) of the solute, and ε _s (f) is the molecular extinction coefficient (l / mol / cm) of the solute.

As described above, the spectrum T _ak (f) can be calculated in advance, and the spectrum T _t (f) can be calculated by measuring the sample container 78-A. Therefore, if the molar concentration c _s (f) of the solute is known in advance. The molecular extinction coefficient ε _s (f) can be evaluated.

(Ii) Method for Evaluating Phase Change Amount Next, the case of evaluating the phase change amount θ _k (f) of a solute present in a sample will be described as an example of the optical characteristics of the sample. This phase change amount θ _k (f) can also be realized by a method similar to the above-described evaluation of the molecular extinction coefficient. It can be considered that the phase change amount θ _k (f) is proportional to the concentration of the solute in the sample.

The phase change amounts obtained by Fourier transforming the intensity signals (time domain signals) measured for the sample containers 78-1 to 78-N filled with the solvent are respectively θ ₁ (f) and θ ₂ (f ,..., Θ _N (f). Further, the phase change amount when the cell gap is zero, that is, when there is no solvent in the sample container, is taken as the reference value in this case. Hereinafter, this reference value is referred to as a reference phase change amount θ ₀ (f). The following equation is established for this reference phase change amount θ ₀ (f).

θ _i (f) = θ ₀ (f) + k (f) · c _{H 2 O} · d _i (7)
However, 1 ≦ i ≦ N, c _H2O is the H ₂ O concentration of pure water (= 1000/18 = 55.5 mol / l), and k (f) is a proportional constant (rad · l) depending on the frequency. / Mol / cm).

Here, if the sample container is filled only with the solvent (water), k (f) · c _{H 2 O} for the solvent is a constant value B. When this constant value B is used to transform equation (7), equation (7 ′) is obtained.

θ _i (f) = B · d _i + θ ₀ (f) (7 ′)
From this equation (7 ′), it can be seen that the change in the phase change amount θ _i (f) with respect to the cell gap d _i is a linear function, and its intercept is θ ₀ (f). That is, the phase change amount θ _k (f) measured from the sample containers 78-1 to 78 -N filled only with the solvent and the corresponding cell gap d _i are plotted, and the intercept expressed by interpolating this plot. Can be calculated as θ ₀ (f).

Further, the phase change amount obtained by Fourier transform of the intensity signal (time domain signal) measured for the sample container 78-A filled with the sample is defined as θ _t (f).

Here, the case where the sample accommodated in sample container 78-A contains the solute of (100- _Ak ) mass% concentration (w / w) is considered. At this time, the sample, A since _k wt% concentration so that the (w / w) of the solvent (water) is included, the theoretical resulting from solvent phase variation theta _{ak (f)} the following Can be expressed as:

θ _ak (f) = θ ₀ (f) −ε (f) · c _{H 2 O} · (A _k / 100) d _k (8)
As described above, since θ ₀ (f) can be calculated in advance based on the measurement results for the sample containers 78-1 to 78 -N, the sample container 78 -A (cell gap d _k and solute concentration (100-A _k) (Theta) _ak (f) in (mass% concentration) is _computable .

Further, the phase change amount θ _s (f) of the terahertz wave absorbed in the solute is derived from the phase change amount θ _t (f) measured for the sample container 78-A filled with the sample and the solvent. Using the theoretical phase change amount θ _ak (f), it can be expressed as follows.

θ _s (f) = θ _ak (f) −θ _t (f) (9)
When the same relationship as the above equation (7) is applied to the equation (9), the following equation is established.

θ _s (f) = θ _ak (f) + k _s (f) · c _s · d _k (10)
However, c _s (f) is the molar concentration (mol / l) of the solute, and k _s (f) is a proportionality constant (rad · l / mol / cm) of the phase change amount of the solute.

As described above, the phase change amount θ _ak (f) can be calculated in advance, and the phase change amount θ _t (f) can be calculated by measuring the sample container 78-A, so that the molar concentration c _s (f) of the solute is determined in advance. If known, the phase change amount k _s (f) can be evaluated.

(Control structure)
FIG. 8 is a block diagram showing a functional configuration of arithmetic device 2 according to the embodiment of the present invention.

  Referring to FIG. 8, the arithmetic device 2 includes a buffer unit 252, a Fourier transform unit (FFT) 254, a sample selection unit 256, a delay stage control unit 258, a setting reception unit 260, a reference calculation unit 262, The solvent characteristic calculation unit 264 and the solute characteristic calculation unit 266 are included as functions thereof. As shown in FIG. 5, these functions are realized by the CPU 200 reading a program stored in advance in the hard disk unit 210 or the like into the memory unit 212 and executing it.

  In addition, a solvent measurement data storage unit 272, a sample measurement data storage unit 274, a sample container setting storage unit 276, and a sample parameter storage unit 278 are formed in the hard disk unit 210 of the arithmetic device 2.

  The buffer unit 252 stores the intensity signal (time domain signal) output from the signal processing unit 12 for at least one sample container. Then, the buffer unit 252 outputs the stored series of intensity signals to the Fourier transform unit 254.

  The Fourier transform unit 254 performs Fourier transform on the intensity signal from the buffer unit 252, and converts the signal from the time domain to the frequency domain. Note that the Fourier transform unit 254 typically performs Fourier transform by using an algorithm of Fast Fourier Transformer (FFT). Note that discrete cosine transform, wavelet transform, or the like may be used instead of fast Fourier transform (FFT).

  As described above, in measuring apparatus 100 according to the present embodiment, terahertz wave T2 is received with the time axis extended, and thus the extended time axis must be reflected when performing Fourier transform. . Therefore, the Fourier transform unit 254 acquires information on the measurement cycle from the delay stage control unit 258, corrects the time axis of the intensity signal stored in the buffer unit 252 based on the measurement cycle information, and then performs the Fourier transform. Execute.

  The delay stage control unit 258 controls the moving speed of the delay stage 50 that determines the measurement period of the terahertz wave T2. Specifically, the delay stage control unit 258 gives the control signal CTRL2 to the delay stage driving mechanism 52, and controls the moving speed of the delay stage 50 to an appropriate value. As described above, the delay stage control unit 258 outputs measurement period information to the Fourier transform unit 254 based on the control signal CTRL2.

  The sample selection unit 256 selects which sample container is irradiated with the terahertz wave T <b> 1 from among the plurality of sample containers arranged on the sample stage 72. Specifically, as will be described later, the sample selection unit 256 refers to the attribute values (such as the type of liquid contained and the value of the cell gap) of each sample container stored in advance in the sample container setting storage unit 276. Then, a control signal CTRL 2 for selecting a necessary sample container is output to the drive mechanism 74. For example, in the reference value calculation process, the sample selection unit 256 sequentially selects sample containers filled only with the solvent.

  In addition, the sample selection unit 256 outputs the currently selected sample information to the Fourier transform unit 254. Based on this sample information, the Fourier transform unit 254 selectively stores the spectrum or phase change obtained by the Fourier transform in the solvent measurement data storage unit 272 or the sample measurement data storage unit 274. That is, when the selected sample container is filled with only the solvent (water), the Fourier transform unit 254 stores the calculated result in the solvent measurement data storage unit 272, and the selected sample container is a solution. If it is satisfied, the calculated result is stored in the sample measurement data storage unit 274.

  The setting receiving unit 260 receives the attribute value of the sample container arranged on the sample table 72 and the known data necessary for the solution measurement, which are input by the user or the like via the input unit 208 (FIG. 5), and the sample container. The data is stored in the setting storage unit 276 and the sample parameter storage unit 278.

  More specifically, in the sample container setting storage unit 276, the “presence / absence of the sample container”, “container of the sample container”, “corresponding to each position of the notch 73 (FIG. 2) of the sample table 72,” Information such as “the size of the cell gap” is stored. The sample parameter storage unit 278 stores information such as “molar concentration of solvent”, “molecular absorption coefficient of solvent”, “wt% concentration of solute”, and “mol concentration of solute”.

The reference calculator 262 calculates a reference value when no solvent is present in the sample container. Specifically, the reference calculation unit 262 refers to the spectra T ₁ (f), T ₂ (f),..., T _N (f) stored in advance in the solvent measurement data storage unit 272. An intercept (log ₁₀ T ₀ (f)) of a linear expression indicating the relationship between the cell gap d _i and log ₁₀ T _i (f) for each frequency is sequentially calculated. Then, the reference calculation unit 262 synthesizes the sequentially calculated intercepts of the linear equations, and outputs them to the solvent characteristic calculation unit 264 as logarithmic values of the reference spectrum.

The solvent characteristic calculation unit 264 calculates the optical characteristic of the solvent. Specifically, the solvent characteristic calculation unit 264 calculates a spectrum T _ak (f) of theoretical transmitted light intensity derived from the solvent. That is, the solvent characteristic calculation unit 264, according to the above equation (4), the logarithmic value log ₁₀ T ₀ (f) of the reference spectrum from the reference calculation unit 262, the predetermined molar concentration of the solvent, and the molecular extinction coefficient Log ₁₀ T _ak (f) is calculated based on the above. Then, the reference calculating unit 262 outputs the logarithmic value of the calculated spectrum of transmitted light intensity to the solute characteristic calculating unit 266.

The solute characteristic calculator 266 calculates the optical characteristics of the solute dissolved in the sample to be measured. Specifically, the solute characteristic calculation unit 266 determines the spectrum T _t (f) stored in advance in the sample measurement data storage unit 274 and the transmitted light intensity from the solvent characteristic calculation unit 264 according to the above-described equation (4). The molecular extinction coefficient of the solute is calculated based on the logarithmic value log ₁₀ T _ak (f) of the spectrum of, the cell gap of the sample container and the molar concentration of the solute. Then, the solute characteristic calculation unit 266 outputs the calculated molecular extinction coefficient of the solute as a measurement result to the display unit 204 (FIG. 5) or the like.

  In the description according to FIG. 8 described above, the configuration in the case of calculating the molecular extinction coefficient of the solute is mainly exemplified as the optical characteristics of the solution. However, since the phase change amount of the solute can be calculated by the same control structure, Detailed description will not be repeated.

(Processing flow)
A series of processing procedures of the solution characteristic measuring method according to the above-described embodiment will be summarized as the following processing flow.

  FIG. 9 is a flowchart showing a processing procedure of the solution property measuring method according to the embodiment of the present invention.

  Referring to FIG. 9, first, the user prepares a sample container containing a sample and a plurality of sample containers containing only the same solvent as the solvent contained in the sample (step S100). Then, the user places these sample containers on the sample table 72 (step S102), and sets the attributes of each sample container and the physical constants of the samples (step S104). Specifically, the user operates the input unit 208 (FIG. 5) and associates the “presence / absence of the sample container” and “sample container” with each position of the notch 73 (FIG. 2) of the sample table 72. Enter information such as “containment (specify sample or solvent)” and “size of cell gap”. In addition, the user inputs known information such as “molar concentration of solvent”, “molecular absorption coefficient of solvent”, “wt% concentration of solute”, and “mol concentration of solute” regarding the target sample. If necessary, the user performs depressurization or nitrogen replacement on a predetermined area including the sample exchange mechanism 70.

When these preparation processes are completed, the user instructs the arithmetic device 2 to start measurement.
In response to the measurement start instruction, the CPU 200 (FIG. 5) of the arithmetic unit 2 gives a control signal CTRL1 to the drive mechanism 74 (FIG. 1), and selects one of the plurality of sample containers arranged on the sample stage 72. Is moved to the irradiation position of the terahertz wave (step S106). Then, the CPU 200 starts measuring the intensity signal for the sample container (step S108). More specifically, the CPU 200 gives the control signal CTRL2 to the delay stage driving mechanism 52 (FIG. 1) and starts generating the pulse laser L1 from the laser light source 20 (FIG. 1). Then, the CPU 200 receives the intensity signal (time domain signal) output from the signal processing unit 12 and performs Fourier transform on the intensity signal to obtain a spectrum or phase change amount.

  CPU 200 stores the acquired spectrum or phase change amount in association with the attribute of the sample container to be measured (step S110). Thereafter, the CPU 200 determines whether or not the measurement for all the sample containers arranged on the sample table 72 has been completed (step S112). When the measurement for all the sample containers is not completed (NO in step S112), CPU 200 executes the process from step S106 onward again.

  On the other hand, when the measurement for all the sample containers has been completed (in the case of YES in step S112), CPU 200 stores only the solvent in the spectrum or phase change amount stored in step S110. The measured value is extracted (step S114), and the value of the cell gap of the sample container is read (step S116). Then, the CPU 200 calculates the reference value by sequentially calculating the intercept of the linear expression indicating the relationship between the cell gap value and the logarithmic value of the spectrum or the phase change amount for each frequency (step S118).

  Subsequently, the CPU 200 calculates the optical characteristics of the solvent based on the reference value calculated in step S118 and the preset molar concentration and molecular extinction coefficient of the solvent (step S120).

  Furthermore, the CPU 200 is based on the spectrum or phase change amount measured for the sample container containing the sample, the optical characteristics of the solvent calculated in step S120, the cell gap of the sample container, and the molar concentration of the solute. Then, the optical characteristics of the solute contained in the sample are calculated (step S122). Then, the CPU 200 outputs the optical characteristics of the solute as a measurement result for the target solution to the display unit 204 (FIG. 5) or the like (step S124). Then, the process ends.

(Measurement example)
Next, a measurement example actually measured using measurement apparatus 100 according to the present embodiment will be described.

  In this measurement example, in order to calculate the reference value, four types of sample containers having cell gaps of 20 μm, 40 μm, 60 μm, and 100 μm are prepared, and in order to measure the sample, a sample container having a cell gap of 100 μm is prepared. Prepared. Moreover, 12 mass% concentration (w / w) arginine aqueous solution was used as a sample.

  FIG. 10 is a diagram illustrating a time waveform of the intensity signal obtained from each sample container in the measurement example.

  FIG. 11 is a diagram showing a spectrum waveform (power spectrum) obtained from the time waveform shown in FIG.

  Referring to FIG. 10, it can be seen that the comparison between sample containers filled with water reduces the peak height of the intensity and delays the peak position as the cell gap increases. The intensity peak height decreases because the degree of water absorption with respect to terahertz waves increases as the cell gap increases. The reason why the peak position is delayed is that the refractive index of water is larger than that of air, so that the propagation speed decreases as the cell gap increases.

  Note that the time waveform of the intensity signal obtained from the sample container filled with the sample shows almost the same behavior as the time waveform of the intensity signal obtained from the sample container filled with water having the same cell gap. Is slight.

  Referring also to FIG. 11, the spectrum of the intensity signal obtained from the sample container filled with the sample (cell gap 100 μm) and the spectrum of the intensity signal obtained from the sample container filled with water (cell gap 100 μm). The difference between them is also slight.

  Thus, it is difficult to obtain sufficient measurement accuracy with the conventional absorption spectrum measurement method.

  10 and 11 show the measurement results when the solution characteristic measurement method according to the present embodiment is applied to the measurement data, as shown in FIGS.

  FIG. 12 is a diagram showing a spectrum waveform (power spectrum) obtained by applying the solution characteristic measurement method according to the present embodiment to the measurement data shown in FIGS. 10 and 11.

  FIG. 13 is a diagram showing a transmittance spectrum of arginine contained in a sample. FIG. 14 is a diagram showing an absorbance spectrum of arginine contained in a sample. FIG. 15 is a diagram showing a molecular extinction coefficient spectrum of arginine contained in a sample.

  Referring to FIG. 12, the reference spectrum is calculated from spectra (see FIG. 11) obtained from a plurality of sample containers filled with water by applying the solution characteristic measuring method according to the present embodiment described above. Can do.

  Based on such a reference spectrum, a spectrum of transmitted light intensity derived from a solute (arginine) contained in the sample can be calculated. As shown in FIG. 12, it can be seen that the spectrum of the transmitted light intensity derived from the solute is larger than the spectrum of the transmitted light intensity measured for the sample container filled with the sample. That is, it shows that the absorbance of the medium is smaller than the absorbance of water.

  As shown in FIGS. 13 to 15, according to the solution characteristic measuring method according to the present embodiment, the optical characteristic of the medium dissolved in the solution can be measured.

(Modification)
In the above-described embodiment, the configuration using the cylindrical sample container is illustrated, but the shape of the sample container is not particularly limited.

FIG. 16 is an external view of a sample container 78 # according to a modification of the embodiment of the present invention.
Referring to FIG. 16, as a sample container, a sample container having a quadrangular prism shape or the like may be used as long as it can accommodate a sample or a solvent contained in the sample. Further, other polygonal column shaped sample containers may be used.

  According to the present embodiment, it is possible to prepare a sample container in which a cell gap is precisely formed, so that the terahertz wave can be more accurately compared with the method of adjusting the distance between parallel windows disclosed in the prior art. Set the propagation path length of. In addition, the sample container for calculating the reference value and the sample container for measuring the optical characteristics of the sample are configured identically except for the cell gap, so the conditions of the interface where the terahertz wave is incident are set. Can be almost identical. That is, the error effects depending on the sample containers can be canceled with each other. Therefore, it is possible to output a measurement result with less error after calculating the reference value (reference value) more accurately.

  According to the present embodiment, the sample container for calculating the reference value and the sample container for measuring the optical characteristics of the sample are arranged on the same sample table 72, and the sample table 72 is rotated and moved. Thus, the measurement results for each sample container can be acquired sequentially. Therefore, the optical properties of the sample can be measured more quickly.

  In addition, according to the present embodiment, each sample container is composed of a concave portion opened on the upper side in the gravitational direction and a lid portion stacked on the upper side in the gravitational direction of the concave portion. There is no fear and measurement can be performed more accurately.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is a schematic block diagram of the solution characteristic measuring apparatus according to embodiment of this invention. It is an external view of the sample exchange mechanism according to an embodiment of the present invention. It is a figure for demonstrating the outline of the measuring method of the time waveform of a terahertz wave. It is a block diagram which shows the schematic function structure in a signal processing part. It is a schematic diagram which shows the schematic hardware constitutions of the arithmetic unit according to embodiment of this invention. It is an external view of the sample container for reference value calculation according to embodiment of this invention. It is an external view of the sample container for accommodating the solution according to the embodiment of the present invention. It is a block diagram which shows the function structure of the arithmetic unit according to embodiment of this invention. It is a flowchart which shows the process sequence of the solution characteristic measuring method according to embodiment of this invention. It is a figure which shows the time waveform of the intensity | strength signal obtained from each sample container in a measurement example. It is a figure which shows the spectrum waveform (power spectrum) obtained from the time waveform shown by FIG. It is a figure which shows the spectrum waveform (power spectrum) obtained by applying the solution characteristic measuring method according to this Embodiment with respect to the measurement data shown in FIG. 10 and FIG. It is a figure which shows the transmittance | permeability spectrum of arginine contained in a sample. It is a figure which shows the light absorbency spectrum of arginine contained in a sample. It is a figure which shows the molecular extinction coefficient spectrum of arginine contained in a sample. It is an external view of the sample container according to the modification of embodiment of this invention.

Explanation of symbols

  2 Arithmetic unit, 12 Signal processing unit, 14 Oscillator, 20 Laser light source, 22 Band pass filter, 24 λ / 2 wave plate, 26 Beam splitter, 28 Emitter unit, 28a Converging lens, 28b Photoconductive switch, 28c Si lens, 30a , 30b, 60a, 60b Off-axis parabolic mirror, 40, 42, 44, 46, 48, 54, 56 Mirror, 50 Delay stage, 52 Delay stage drive mechanism, 58 Antenna unit, 58a Converging lens, 58b Photoconductive switch 58c Si lens, 70 Sample exchange mechanism, 72 Sample stand, 72a Press plate, 73 Notch, 73a Through hole, 74b Motor, 74 Drive mechanism, 74a Rotation support, 78 Sample container, 781a-78Na, 78Aa Lid, 781b-78Nb, 78Ab recess , 781c storage unit, 100 solution characteristic measurement device (measurement device), 121 multiplier, 122 low-pass filter, 204 display unit, 206 interface unit, 208 input unit, 210 hard disk unit (HDD), 212 memory unit, 214 CD -ROM drive, 214a CD-ROM, 216 FDD drive, 216a flexible disk, 252 buffer unit, 254 Fourier transform unit, 256 sample selection unit, 258 delay stage control unit, 260 setting reception unit, 262 reference calculation unit, 264 solvent characteristics Calculation unit, 266 Solute characteristic calculation unit, 272 Solvent measurement data storage unit, 274 Sample measurement data storage unit, 276 Sample container setting storage unit, 278 Sample parameter storage unit, L1, L2, L3 pulse laser , T1, T2 Terahertz waves.

Claims (5)

A solution property measuring device for measuring properties of a solution comprising a solvent and a solute,
A terahertz source that generates terahertz waves;
A first sample container and a plurality of second sample containers each having a container for containing a liquid;
A sample stage for holding the first sample container and the plurality of second sample containers;
For selectively arranging one sample container among the first sample container and the plurality of second sample containers on the propagation path of the terahertz wave from the terahertz generation source by driving the sample stage A drive mechanism;
A receiver for receiving the terahertz wave after passing through the sample container;
A signal processing unit that outputs an intensity signal indicating the intensity of the terahertz wave received by the receiving unit;
A calculation unit that calculates the characteristics of the solution based on an intensity signal from the signal processing unit;
The first sample container contains the solution;
The plurality of second sample containers contain the solvent,
The accommodating portions of the plurality of second sample containers are formed so that the thicknesses along the propagation path of the terahertz wave are different from each other,
The computing unit is
Means for calculating a reference value based on an intensity signal for each of the plurality of second sample containers;
Means for calculating a property relating to the solvent based on the reference value;
And a means for calculating a characteristic relating to the solute based on a characteristic relating to the solvent and an intensity signal relating to the first sample container.   The means for calculating the reference value calculates the reference value based on a correspondence relationship between the thickness of the container and the value of the intensity signal in each of the plurality of second sample containers. The solution property measuring apparatus as described. Each of the first sample container and the plurality of second sample containers is composed of a concave portion opened on the upper side in the gravitational direction and a lid portion stacked on the upper side in the gravitational direction of the concave portion,
The solution characteristic measuring apparatus according to claim 1, wherein a terahertz wave from the terahertz generation source is incident on the target sample container along a direction of gravity.   The sample stage selects a sample container disposed on a propagation path of the terahertz wave by rotating the first sample container and the plurality of second sample containers with respect to a horizontal plane. The solution property measuring apparatus as described. A solution property measuring method for measuring properties of a solution composed of a solvent and a solute using a measuring device,
The measuring device is
A terahertz source that generates terahertz waves;
A first sample container and a plurality of second sample containers each having a container for containing a liquid;
A sample stage for holding the first sample container and the plurality of second sample containers;
A receiver for receiving the terahertz wave after passing through the sample container;
A signal processing unit that outputs an intensity signal indicating the intensity of the terahertz wave received by the receiving unit;
The sample stage is movable so that one sample container among the first sample container and the plurality of second sample containers is selectively disposed on a propagation path of the terahertz wave from the terahertz generation source. Configured,
The first sample container contains the solution;
The plurality of second sample containers contain the solvent,
The accommodating portions of the plurality of second sample containers are formed so that the thicknesses along the propagation path of the terahertz wave are different from each other,
The solution property measuring method is:
Sequentially moving the sample stage to obtain an intensity signal for each of the first sample container and the plurality of second sample containers;
Calculating a reference value based on an intensity signal for each of the plurality of second sample containers;
Calculating a property relating to the solvent based on the reference value;
Calculating a characteristic relating to the solute based on the characteristic relating to the solvent and an intensity signal relating to the first sample container.

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