JP7114425B2 - Electron spin resonance measurement device and its adjustment method - Google Patents

Description

TECHNICAL FIELD The present invention relates to an electron spin resonance (hereinafter also referred to as "ESR" in some cases) measurement apparatus and adjustment method thereof, and more particularly to adjustment of the high-frequency magnetic field direction.

Generally, when measuring electron spin resonance, a sample is placed in a cavity (resonator) placed in a static magnetic field. Within the cavity, electromagnetic energy is imparted to the electron spins in the sample. When the electromagnetic wave energy (hν) matches the Zeeman energy (gμBo) due to the static magnetic field (Bo), the sample absorbs the electromagnetic wave energy, and the phenomenon is observed as electron spin resonance. where h is Planck's constant, ν is the frequency of the electromagnetic wave, g is the g-value, and μ is the magnetic moment of the electron. Patent document 1 shows an example of a cavity for electron spin resonance measurement.

Within the cavity, the electromagnetic waves generate a high-frequency magnetic field (B ₁ ). According to the selection rule, a transition is allowed if the difference ΔMs of the quantum numbers exchanged is ±1. That transition is called an allowed transition. In order to observe electron spin resonance that obeys the selection rule, the radio-frequency magnetic field is formed such that the direction of the radio-frequency magnetic field is perpendicular to the direction of the static magnetic field. Such a resonance mode of a high-frequency magnetic field is called a magnetic field orthogonal mode (B⊥ mode) (the symbol attached to B means vertical or orthogonal). In general electron spin resonance measurements, electron spin resonance is observed using a cavity for magnetic field orthogonal modes.

On the other hand, transitions may occur under conditions that violate the selection rule (eg, ΔMs=±2). Such abnormal transitions are called forbidden transitions. For example, when the value of the spin angular momentum S of the molecules contained in the sample is an integer (S≧1), or when ΔMs=±1 and the nuclear spin transition ΔMI=±1 occur simultaneously, the forbidden transition occurs. occur. Electron spin resonance is also observed when forbidden transitions occur.

When peaks corresponding to allowed transitions (allowed transition peaks) and peaks corresponding to forbidden transitions (forbidden transition peaks) are mixed in the observed ESR spectrum, it is generally difficult to distinguish between the two. In this regard, a method has been proposed for selectively observing forbidden transitions using a special resonator called a dual mode cavity. A dual-mode cavity is a special cavity that achieves two resonant modes with a relatively small frequency difference (for example, a frequency difference of several hundred MHz) within one cavity resonator. In such a cavity, one resonant mode forms a high-frequency magnetic field near the sample that is orthogonal to the static magnetic field (magnetic field orthogonal mode), and electron spin resonance due to allowed transitions and forbidden transitions is observed. In the other resonance mode, a high-frequency magnetic field parallel to the static magnetic field is formed near the sample (magnetic field parallel mode), and only electron spin resonance due to forbidden transitions is observed. The magnetic field parallel mode is written as B∥ mode (the symbol attached to B is a symbol that means parallel).

JP 2011-185748 A

Correct measurement results cannot be obtained if the high-frequency magnetic field coordinate system does not match the static magnetic field coordinate system. For example, in the parallel magnetic field mode, only forbidden transition peaks should occur in the ESR spectrum, but if there is a deviation between the two coordinate systems, the ESR spectrum will show forbidden transition peaks and allowed transition peaks. A peak also occurs. When installing the cavity, the position and orientation of the cavity are determined so that it is correctly oriented with respect to the static magnetic field. However, there may be errors in the position and orientation of the specimen, and when the sample tube or sample is placed in the cavity, the actual direction of the high-frequency magnetic field is not ideal (in the magnetic field orthogonal mode, it is different from the static magnetic field direction). It may deviate from the orthogonal direction (the direction parallel to the static magnetic field direction in the magnetic field parallel mode).

SUMMARY OF THE INVENTION An object of the present invention is to provide an electron spin resonance measurement apparatus and an adjustment method thereof that can eliminate or reduce the deviation of the high-frequency magnetic field direction.

An electron spin resonance measurement apparatus according to an embodiment includes a static magnetic field generator that generates a static magnetic field, a cavity that applies a high-frequency magnetic field that causes electron spin resonance to a sample, and a state in which the sample is placed in the cavity. and adjusting means for adjusting the direction of the high-frequency magnetic field so that the direction of the high-frequency magnetic field has a predetermined relationship with the direction of the static magnetic field.

According to the above configuration, it is possible to match the direction of the high-frequency magnetic field with the direction of the static magnetic field by the adjustment means. That is, it is possible to correctly match the high-frequency magnetic field coordinate system with the static magnetic field coordinate system. The adjustment means is a mechanism for changing the orientation of the cavity relative to the static magnetic field, and may adjust the position and posture of the cavity or the position and posture of the static magnetic field generator. In general, since the static magnetic field generator is large and heavy, it is more advantageous to move the cavity side. As an adjustment method, mechanical adjustment as well as electrical adjustment can be considered.

In embodiments, said adjustment means is a mechanical adjustment mechanism for adjusting the spatial relationship between said static magnetic field generator and said cavity. In one embodiment, the mechanical adjustment mechanism is a mechanism that rotates the coordinate system of the high-frequency magnetic field about at least two axes relative to the coordinate system of the static magnetic field.

In embodiments, the cavity functions to generate the high-frequency magnetic field in both a magnetic field orthogonal mode and a magnetic field parallel mode.

An electron spin resonance measurement apparatus according to an embodiment includes a waveguide that supplies microwaves to the cavity, and the waveguide includes a fixed portion on the microwave generator side and a movable portion connected to the cavity. and a flexible portion connecting between the fixed portion and the movable portion. The flexible portion enables reliable transmission of microwaves even when the movable portion moves.

A method according to an embodiment is an adjustment method for matching the direction of a high-frequency magnetic field generated in a cavity containing a sample with respect to the direction of a static magnetic field in an electron spin resonance measurement apparatus, wherein the cavity is rotated on a trial basis. a trial step of acquiring a plurality of electron spin resonance signals corresponding to a plurality of rotation angles by means of a retrieving step; a specifying step of specifying a misorientation based on the plurality of electron spin resonance signals; and an adjustment step of rotating the cavity. Calculation of misorientation and rotation of the cavity may be performed manually.

In an embodiment, at least one of a permitted transition peak and a forbidden transition peak in an electron spin resonance spectrum is observed when acquiring the plurality of electron spin resonance signals.

According to the present invention, it is possible to eliminate or reduce the deviation of the direction of the high-frequency magnetic field.

1 is a block diagram showing a general ESR measuring device; FIG. It is a perspective view which shows a magnetic field orthogonal mode. It is a top view which shows a magnetic field orthogonal mode. FIG. 4 is an enlarged view showing allowed and forbidden transition peaks observed in magnetic field orthogonal mode; FIG. 4 shows an ESR spectrum observed in magnetic field orthogonal mode; It is a perspective view which shows a magnetic field parallel mode. It is a top view which shows a magnetic field parallel mode. FIG. 4B is an enlarged view showing the forbidden transition peaks observed in the field-parallel mode; FIG. 4 shows an ESR spectrum observed in magnetic field parallel mode; FIG. 4 is a diagram showing the spatial relationship between a static magnetic field coordinate system and a high frequency magnetic field coordinate system; FIG. 4 shows multiple allowed transition peaks contained in an ESR spectrum observed in field-parallel mode; 1 is a block diagram showing an ESR measuring device according to an embodiment; FIG. It is a perspective view showing an adjustment mechanism. It is a side view which shows an adjustment mechanism. It is a top view which shows an adjustment mechanism. 4 is a flow chart showing an adjustment method according to the embodiment; FIG. 10 is a diagram showing changes in ESR signal intensity with variation in angle β; FIG. 10 is a diagram showing changes in ESR signal intensity with variation in angle α; It is a figure which shows an experimental result.

(1) Common ESR Measuring Apparatus and Description of Problems FIG. 1 shows an outline of a common ESR measuring apparatus. The illustrated ESR measurement apparatus is an apparatus for measuring electron spin resonance according to the CW method.

A sample 10 to be measured is placed in a cavity 12 . Microwaves are supplied to the cavity 12 . Cavity 12 is hollow and acts as a resonator for microwaves. A high frequency magnetic field (B ₁ ) is generated within the cavity. Note that the sample 10 is gas, liquid or solid.

The static magnetic field generator 14 is composed of a pair of electromagnet coils or the like that generate a static magnetic field (B ₀ ). The strength of the static magnetic field is swept to induce electron spin resonance. Alternatively, a static magnetic field is generated with a strength that causes electron spin resonance. In the illustrated configuration example, a magnetic field modulation coil 16 is arranged between the static magnetic field generator 14 and the sample 10 . The magnetic field modulation coil 16 generates a modulated magnetic field that modulates the static magnetic field by being superimposed on the static magnetic field. A magnetic field modulation signal generated by a magnetic field modulation signal generator 24 is applied to the magnetic field modulation coil 16 . The microwave generator 18 is for generating microwaves. The attenuator 20 is a circuit that adjusts the power or intensity of the generated microwave. A microwave that has passed through the attenuator is introduced into the cavity 12 via the circulator 22 .

In the sweeping process of the static magnetic field, when certain resonance conditions are met, the electron spins in the sample interact with the microwaves and enter a resonance state. At this time, the tuning balance of the cavity 12 is lost, and the reflected wave oscillating at the modulation frequency leaks out of the cavity 12 . A reflected wave leaking from the cavity 12 passes through the circulator 22 and is input to the detection circuit 25 as a reflected wave signal. The detection circuit 25 is a circuit for detecting a reflected wave signal by mixing a microwave frequency signal with the reflected wave signal. The output signal of the detection circuit 25 is input to a phase detector 32 configured as, for example, a lock-in amplifier via an amplifier 30, where it undergoes phase detection. A detection signal having the same frequency as the magnetic field modulation signal generated by the magnetic field modulation signal generator 24 is input to the phase detector 32 . The detection signal is mixed with the signal output from the amplifier 30 . As a result, a DC signal is generated as a signal after detection. The DC signal is converted into a digital signal by an A/D converter 34 and the converted digital signal is input to a personal computer (PC) 36 . An ESR spectrum is generated in the PC 36 .

The cavity 12 shown in FIG. 1 has the function of generating two resonant modes. Among those resonant modes, one is the TE ₁₀₂ mode, which is the magnetic field quadrature mode. The other is the TE ₀₁₂ mode, which is the magnetic parallel mode.

Cavity 12 is shown in FIG. 2 and the TE ₁₀₂ mode is shown. The Y direction is the direction of the static magnetic field (B ₀ ), and the two directions orthogonal thereto are the X direction and the Z direction. Here the Z direction is the direction of the high frequency magnetic field (B ₁ ). Reference 10A indicates the direction in which the sample is introduced.

A plan view of the cavity 12 is shown in FIG. A sample resides in the center of cavity 12 . At that location, the direction of the radio-frequency magnetic field (B ₁ ) is orthogonal to the direction of the static magnetic field (B ₀ ).

FIG. 4 schematically shows part of an ESR spectrum that can be acquired in the magnetic field orthogonal mode described above. The horizontal axis indicates the static magnetic field strength, and the vertical axis indicates the strength of the ESR measurement signal. In the figure, the right peak is the allowed transition peak, and the left peak is the forbidden transition peak.

FIG. 5 shows the ESR spectrum 38 actually acquired in the above magnetic field orthogonal mode. The samples are Mn ²⁺ /MgO powders. In FIG. 5, symbols 40 indicate permissible transitions (static magnetic field strengths at which permissible transitions can occur), and symbols 42 indicate forbidden transitions (static magnetic field strengths at which forbidden transitions can occur). The ESR spectrum contains multiple forbidden transition peaks, which are very small and difficult to distinguish in FIG. In any case, in the magnetic field orthogonal mode, both electron spin resonances due to allowed transitions and electron spin resonances due to forbidden transitions can be observed.

Cavity 12 is shown in FIG. 6 and the TE ₀₁₂ mode is shown. Elements that have already been described are given the same reference numerals, and their description is omitted. This also applies to each drawing described below.

A plan view of the cavity 12 is shown in FIG. A sample resides in the center of cavity 12 . At that location, the direction of the radio-frequency magnetic field (B ₁ ) is parallel to the direction of the static magnetic field (B ₀ ). Note that the direction of the high-frequency magnetic field (B ₁ ) is periodically reversed.

FIG. 8 schematically shows part of the ESR spectrum that can be acquired in the magnetic field parallel mode described above. In the figure, the right peak is the forbidden transition peak. In FIG. 8, no allowed transition peaks are observed.

The lower part of FIG. 9 shows the ESR spectrum 44 actually obtained in the magnetic field parallel mode. The samples are Mn ²⁺ /MgO powders as described above. 9 also shows the ESR spectrum 38 shown in FIG. 5 for comparison.

In the lower part of FIG. 9, the symbol indicated by reference numeral 42 indicates forbidden transitions (magnetic field strengths that can cause forbidden transitions). The ESR spectrum 44 contains forbidden transition peaks but not allowed transition peaks. That is, in the magnetic field parallel mode, basically only electron spin resonance due to forbidden transitions is observed.

Next, the deviation of the coordinate system and the problems caused by it will be described.

FIG. 10 shows an XYZ coordinate system. The Y direction is the direction of the static magnetic field (B ₀ ), and the X and Z directions are directions orthogonal to the Y direction. Therefore, the XYZ coordinate system can also be said to be a static magnetic field coordinate system. Ideally, the direction of the high-frequency magnetic field (B ₁ ) coincides with the Y direction in the magnetic field parallel mode. However, due to the inclination of the cavity, the inclination of the sample tube in the cavity, the influence of other substances, etc., the direction of the high-frequency magnetic field may deviate from the Y-axis as shown in FIG. In the figure, the high-frequency magnetic field in which the deviation occurs is exaggerated by B ₁ ^* . A principal axis 50 is defined as a direction perpendicular to the Y-axis and the high-frequency magnetic field B ₁ ^* . The angle of rotation of the high-frequency magnetic field B ₁ ^* from the Y-axis is α, and the angle of rotation of the principal axis 50 from the Z-axis is β. They are called Euler angles. Another Euler angle is γ. However, it is the Euler angles α and β that usually pose a problem in terms of mechanical errors and the like in the parallel magnetic field mode, and γ=0 is assumed below.

In the magnetic field parallel mode (B∥ mode), the vector of the ideal high-frequency magnetic field B ₁ is expressed as (0, B ₁ , 0). The high-frequency magnetic field B ₁ ^* after rotation is expressed by the following equation (1) using a rotation matrix.

The Y component in the above equation ( ¹ ) is a component parallel to the static magnetic field, and the electron spin resonance signal of the forbidden transition is proportional to the Y component. (2) It is expressed as in the formula.

^On the other hand, the component perpendicular to the static magnetic field is expressed as the vector sum of the X component and the Y component in the above equation (1). is expressed as

As shown in the above equation (3), when a mechanical position error occurs due to changes in the orientation of the cavity, the orientation of the sample tube, etc., even though only forbidden transitions are observed, Instead, even permissible transitions are observed.

FIG. 11 shows an ESR spectrum 48 acquired in magnetic field parallel mode. The ESR spectrum 48 includes allowed transition peaks as well as forbidden transition peaks. In such a case, it becomes difficult to analyze the ESR spectrum 48 correctly.

(2) Description of Embodiment FIG. 12 shows an ESR measuring device according to an embodiment. Components similar to those shown in FIG. 1 are denoted by the same reference numerals, and descriptions thereof are omitted.

In FIG. 12, the cavity 52 can operate in the magnetic field orthogonal mode and the magnetic field parallel mode as described above. A sample 54 is positioned within the cavity 52 . Examples of the sample 54 include a paramagnetic substance capable of simultaneously observing forbidden transitions and allowed transitions, and a paramagnetic substance capable of observing only allowed transitions. However, substances other than these can be used depending on the measurement method.

Cavity 52 is held by adjustment mechanism 56 . The adjustment mechanism 56 is a mechanism for adjusting the posture of the cavity, in other words, a mechanism for aligning the high-frequency magnetic field coordinate system with the static magnetic field coordinate system and matching the high-frequency magnetic field direction with the static magnetic field direction. is. A specific configuration example thereof will be described later with reference to FIG. 13 and subsequent drawings.

The PC 58 as an information processing device is a device for observing ESR signals, and an ESR spectrum is created in the PC 58 . The PC 58 has a calculation section 60 that executes calculations required for adjusting the attitude of the cavity 52 . Changes in the ESR signal intensity are observed when the angles α and β, which will be described later, are individually varied. An α table 64 and a β table 66 representing the observation results are constructed on the storage unit 62 . Correction angles (deviation angles) Δα and Δβ are specified by referring to or analyzing the α table 64 and β table 66 . The posture of the cavity, that is, the direction of the high-frequency magnetic field is manually adjusted according to the correction angles Δα and Δβ. The calculation of the correction angles Δα and Δβ and the control of orientation adjustment according to the correction angles Δα and Δβ may be automatically executed in the PC 58 . A reference numeral 67 indicates a control signal when the PC 58 controls the operation of the adjusting mechanism 56 .

FIG. 13 schematically shows a main part of the adjustment mechanism 56. As shown in FIG. Cavity 52 is a dual mode cavity, which is specifically a rectangular cavity. A cylindrical cavity resonator may be used as the cavity 52 . A waveguide 70 is connected to one side of the cavity 52 and a waveguide 72 is connected to the other side of the cavity. Waveguide 70 guides microwaves that produce magnetic field orthogonal modes into cavity 52 , and waveguide 72 guides microwaves that produce magnetic field parallel modes into cavity 52 . The waveguide 70 has a rectangular cavity on the XY cross section, and the longitudinal direction of the cavity is the X direction. The waveguide 72 has a rectangular cavity on the XY cross section, and the longitudinal direction of the cavity is the Y direction. Interval adjusters 96 and 98 are provided midway between the two waveguides 70 and 72, and the interval adjusters 96 and 98 are conceptually shown in FIG.

Two waveguides 70, 72 are joined at their upper ends to a horizontal waveguide 74. FIG. A lower end of a flexible waveguide 76 is connected to the horizontal waveguide 74 . A waveguide 78 is connected to the upper end of the flexible waveguide 76 . A cavity 80 in waveguide 78 connects to cavities in each of waveguides 70 and 72 via a cavity in flexible waveguide 76 and a cavity in horizontal waveguide 74, and further to cavities in cavity 52. connected to the inside. Microwaves are supplied into the cavity 52 via those waveguides, and reflected waves from the cavity 52 are output to the outside via those waveguides.

Waveguide 78 is a fixed part, which is fixed relative to the fixture. Horizontal waveguide 74 and waveguides 70, 72 are shape-invariant moving parts. A flexible waveguide 76 as a shape-changeable flexible portion is provided between the fixed portion and the movable portion. A flexible waveguide 76 allows a change in the position or orientation of the movable portion relative to the fixed portion. The flexible waveguide 76 has an accordion-like structure in the embodiment. Waveguides having other structures may be employed as flexible waveguides.

A flange is formed at the lower end of the waveguide 78, and a flange is also formed at the upper end of the flexible waveguide. The flanges are connected while being superimposed. A similar structure can be adopted for other connecting portions.

A fixed plate 82 is connected to the flange forming the lower end of the waveguide 78 , and a movable plate 84 is connected to the flange forming the lower end of the flexible waveguide 76 . Fixed plate 82 is a horizontal plate that does not move. The movable plate 84 is integrated with the movable portion, and the movable plate 84 moves as the posture of the movable portion changes. Conversely, when the attitude of the movable plate 84 is changed, the attitude of the movable portion is accordingly changed.

Two screws 90 and 92 spaced apart in the Y direction are fixed to the fixing plate 82 so as to be able to advance and retreat. The angle of the movable plate 84 with respect to the fixed plate 82 changes according to the amount of protrusion of the screws 90 and 92 (the amount of protrusion toward the movable plate 84 side). As a result, the cavity 52 swings. The direction of oscillating motion is indicated at 100 . It is the direction in which the angle β changes.

A scale 86 is provided on the fixed plate 82 along the circumferential direction. On the other hand, the movable plate 84 is provided with a marker 88 . If the fixed plate 82 is made of a transparent or translucent material, for example, the markers 88 can be seen through the graduations 86 . In addition, the movable plate 84 is provided with an inclination angle detector (horizontal) 94 . The tilt angle detector 94 detects the tilt angle in the direction indicated by reference numeral 100 (the direction in which the angle β changes). Spacing adjusters 96 and 98 can be used to rotate cavity 52 in the direction indicated by reference numeral 102 .

14 is a side view of the adjustment mechanism 56. FIG. Reference numeral 104 indicates the origin. Illustration of a modulated magnetic field generator and the like is omitted.

Bases 110 and 112 hold waveguide 78 as a fixed portion via horizontal arms 114 and 116 . Bases 110, 112 and arms 114, 116 correspond to jigs. Incidentally, a circulator is connected to the tip of the waveguide 78 . Two screws 90 and 92 are provided across the fixed plate 82 and the movable plate 84 . The change in the amount of protrusion of them determines the attitude of the movable plate 84, that is, the tilt angle of the cavity 52. FIG.

Interval adjusters 96 and 98 are provided in the middle of waveguides 70 and 72 as described above. The tip of the gap adjuster 96 is brought into contact with the base 106 to which the electromagnet 14A is fixed, and the tip of the gap adjuster 98 is brought into contact with the base 108 to which the electromagnet 14B is fixed. Details of the spacing adjusters 96 and 98 will be described with reference to FIG. 15 shown below. For example, it is possible to identify the correction angle Δβ by monitoring the intensity of the allowed transition peak observed in the magnetic field parallel mode while changing the angle β. After that, by adjusting the angle according to the correction angle Δβ, it is possible to make the angle deviation at the angle β zero.

FIG. 15 is a plan view of the adjusting mechanism. The gap adjuster 96 has a sleeve 120 and a retractable pin 122 . Rotation of sleeve 120 causes pin 122 to advance and protrude or retract pin 122 to retract into sleeve 120, depending on the direction of rotation. That is, the position of the waveguide 70 in the Y direction is defined by the sleeve 120 and the retractable pin 122 . A spring 128 is provided inside the holder 126, and the spring 128 applies an elastic biasing force to the head 130 in the -Y direction. The position of the head 130 follows and changes according to the distance between the base 106 and the waveguide 70 . Spacing adjuster 98 has a configuration similar to that of spacing adjuster 96 described above, namely, sleeve 132 , pin 134 , holder 136 , spring 138 and head 140 . A spacing adjuster 98 defines the position of the waveguide 72 in the Y direction.

The two spacing adjusters 96 , 98 make it possible to vary the angle of the movable portion and the cavity 52 about the central axis passing through the origin 104 . The angle can be read from the positional relationship between scale 86 and marker 88 . For example, it is possible to specify the correction angle Δα by monitoring the intensity of the allowed transition peak observed in the parallel magnetic field mode while changing the value of the angle α. After that, by performing angle adjustment according to the correction angle Δα, it is possible to make the angle deviation at the angle α zero.

Next, an adjustment method according to the embodiment will be described with reference to FIG. 16 . When executing the adjustment method, the adjustment mechanism described above is used.

A method of adjusting the angle α after adjusting the angle β will be described below. However, the angle β may be adjusted after adjusting the angle α. Alternatively, the angle deviation Δα for the angle α and the angle deviation Δβ for the angle β may be determined individually, and the two angle deviations Δα and Δβ may be corrected collectively.

At S10, a cavity is placed in a static magnetic field and a sample is placed within the cavity. At S12, the angle α is made zero and the angle β is made zero. However, at this stage, the angle β may be set to an initial value having a certain magnitude. Similarly, the angle β may be set to zero and the angle α may be set to an initial value having a certain magnitude before executing S26, which will be described later. At S12, other necessary initial settings are performed. At S14, preparations are made for executing the magnetic field parallel mode. For example, a waveguide for magnetic field parallel mode is selected as the channel for supplying microwaves.

At S16, a trial ESR measurement is performed to generate an ESR spectrum. The intensity of allowed transition peaks (the intensity of a specific allowed transition peak, the average intensity of a plurality of allowed transition peaks, etc.) included in the ESR spectrum is observed. Its intensity is recorded in association with the angle β. The recording may be done manually. At S16, the intensity of the forbidden transition peak may be observed and recorded along with the intensity of the allowed transition peak. In S18, it is determined whether or not to repeat the step of S16. At S20, the angle β is changed, and then S16 is executed again. By repeating the step of S16, a table (β table) consisting of intensities of a plurality of allowable transition peaks corresponding to a plurality of angles β is created.

In S22, by performing function fitting based on the above equation (2) based on the table, the correction angle Δβ is obtained from the minimum value of the curve obtained thereby. The computation can be performed automatically on the PC or performed manually. In the above local minimum situation, the coincidence of the direction of the static magnetic field and the direction of the radio-frequency magnetic field can be estimated with respect to the angle β. At S24, the β angle of the cavity is set based on the correction angle Δβ.

Subsequently, steps after S26 are executed to correct the angle α. In S26, similarly to S16 above, ESR measurement is performed on a trial basis under the set angle α to generate an ESR spectrum. The intensity of allowed transition peaks (the intensity of a specific allowed transition peak, the average intensity of a plurality of allowed transition peaks, etc.) included in the ESR spectrum is observed. Its intensity is recorded in association with the angle α. In doing so, the intensity of the forbidden transition peak may be observed and recorded. In S28, it is determined whether or not to repeat the step of S26. At S30, the angle α is changed, and then S26 is executed again. By repeating the step of S26, a table (α table) is created that consists of the intensities of a plurality of allowable transition peaks corresponding to a plurality of angles α.

In S32, the minimum value of the curve is specified by performing function fitting based on the above equation (2) based on the table. A correction angle Δα is obtained from the minimum value. The computation can be performed automatically on the PC or performed manually. In the above local minimum situation, the coincidence of the direction of the static magnetic field and the direction of the radio-frequency magnetic field can be estimated with respect to the angle α. In S34, the α angle of the cavity is set based on the correction angle Δα. After the above adjustments, that is, after correcting the direction of the high-frequency magnetic field with respect to the direction of the static magnetic field, the ESR spectrum of the sample is observed.

FIG. 17 shows plot results of the contents of the β table. The angle β is changed stepwise from β1 to β5. The minimum value has not been reached. A function 150 is derived by function fitting to the plotted results, and the local minimum of the function 150 is estimated. Here, the correction angle Δβ is calculated as the angular interval up to the angle corresponding to the minimum value with β5 as the reference. That is, Δβ is added to the current angle β5 in order to eliminate the angle deviation. The correction angle Δβ may be calculated with reference to the point where the angle β=0.

FIG. 18 shows plot results of the contents of the α table. The angle α is changed stepwise from α1 to α5. The minimum value has not been reached. A function 152 is derived by fitting based on the plotted results, and the local minimum of the function 152 is estimated. Here, the corrected angle Δα is calculated as the angular interval up to the angle corresponding to the minimum value with α5 as the reference. That is, Δα is added to the current angle α5 in order to eliminate the angular deviation. The correction angle Δβ may be calculated with reference to the point where the angle α=0.

FIG. 19 shows experimental results for the angle α. A function 154 is derived by function fitting to the plotted results. A correction angle Δα is calculated from the function 154 .

In the above embodiment, the minimum value of allowed transition peaks is used, but it is also possible to use the maximum value of forbidden transition peaks. As already explained, the angle α may be adjusted first and then the angle β. Alternatively, the two angle correction values may be obtained independently, and finally the two angle correction values may be applied.

The same sample may be used for the trial measurement and the main measurement, or different samples may be used. The adjustment mechanism described in the embodiment is for explaining the principle in an easy-to-understand manner, and the content thereof is merely an example. A cavity corresponding to both the magnetic field orthogonal mode and the magnetic field parallel mode may be used with one port.

14 static magnetic field generators, 52 cavities, 54 samples, 58 PCs, 60 computing units, 64 α tables, 66 β tables.

Claims (6)

a static magnetic field generator for generating a static magnetic field;
a cavity that provides a high frequency magnetic field that induces electron spin resonance for the sample;
A space between the static magnetic field generator and the cavity so that the direction of the high-frequency magnetic field is orthogonal to or parallel to the direction of the static magnetic field when the sample is placed in the cavity. an adjusting means for adjusting the relationship ;
An electron spin resonance measurement device comprising: In the electron spin resonance measurement device according to claim 1,
The adjustment means is a mechanical adjustment mechanism that adjusts the position and orientation of the cavity with respect to the static magnetic field generator.
An electron spin resonance measurement device characterized by: In the electron spin resonance measurement device according to claim 2,
The mechanical adjustment mechanism is a mechanism that rotates the coordinate system of the high-frequency magnetic field about at least two axes relative to the coordinate system of the static magnetic field.
An electron spin resonance measurement device characterized by: a static magnetic field generator for generating a static magnetic field;
a cavity that provides a high frequency magnetic field that induces electron spin resonance for the sample;
adjusting means for adjusting the direction of the high-frequency magnetic field so that the direction of the high-frequency magnetic field has a predetermined relationship with the direction of the static magnetic field when the sample is placed in the cavity;
including
The cavity has a function of generating the high-frequency magnetic field in both magnetic field orthogonal mode and magnetic field parallel mode,
An electron spin resonance measurement device characterized by: a static magnetic field generator for generating a static magnetic field;
a cavity that provides a high frequency magnetic field that induces electron spin resonance for the sample;
adjusting means for adjusting the direction of the high-frequency magnetic field so that the direction of the high-frequency magnetic field has a predetermined relationship with the direction of the static magnetic field when the sample is placed in the cavity;
including
said adjustment means is a mechanical adjustment mechanism for adjusting the spatial relationship between said static magnetic field generator and said cavity;
a waveguide is provided to supply microwaves to the cavity;
The waveguide includes a fixed portion on the microwave generator side, a movable portion connected to the cavity, and a flexible portion connecting the fixed portion and the movable portion,
An electron spin resonance measurement device characterized by: A method for adjusting the direction of a high-frequency magnetic field generated in a cavity containing a sample with respect to the direction of a static magnetic field in an electron spin resonance measurement apparatus, comprising:
a trial step of trially rotating the cavity to obtain a plurality of electron spin resonance signals corresponding to a plurality of rotation angles;
an identifying step of identifying a misorientation based on the plurality of electron spin resonance signals;
an adjusting step of rotating the cavity so that the misorientation is eliminated;
including
When acquiring the plurality of electron spin resonance signals, at least one of an allowed transition peak and a forbidden transition peak in an electron spin resonance spectrum is observed.
A method for adjusting an electron spin resonance measurement device, characterized by:

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