JPH05508933A - Portable dedicated electron spin resonance spectrometer - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Portable electron spin resonance spectrometer Background of the invention The present invention relates to electron spin resonance (ESR) spectrometers, and more particularly to electron spin resonance (ESR) spectrometers. This invention relates to a portable electron spin resonance spectrometer exclusively for applications.

Applications include, among others, immunology, such as determining antigen-antibody reactions and determining the presence of drugs in body fluids. chemical testing, determining the presence of any impurities in motor vehicle oil or other liquids, Exploration of crude oil flow, spin labeled matter (spin 1abelle A security system where there is a card with d material) added, archaeologically including the dating of finds. Today, blood and A large amount of work is done to test urine. The substance labeled by spin is A card such as a credit card is sealed and an ESR sensor is used to protect the card. The card is read and the holder of the card is allowed to enter the secure facility. The application of ESR technology in security-related fields, such as determining whether is expected.

Electron spin resonance spectrometers are used as laboratory instruments and typically weigh up to 1 ton. It is known as a research device with a magnet of weight However, such devices are too large and heavy to be portable. Ru. Even conventional, rather small benchtop devices are still too heavy to fit in an office. or cannot be easily moved from the laboratory to the field for analytical work. .

However, in order to perform a special and narrowly defined type of analysis that is easily portable, There is a need for an ESR electron spin resonance spectrometer that can be taken to the field. like that The ESR must be operable by field personnel with minimal training. No. In the case of ESR in ordinary large laboratories, due to the nature of the method used, requires a high level of training.

Summary of the invention The present invention utilizes a particularly small and lightweight permanent magnet, a microwave source, and a circular and a resonator containing a sample having the properties to be determined. Provides a spin resonance spectrometer, in which the resonator is inductively coupled to a circulator and its coupling by means of a closed-loop matching network that operates to optimize inductive coupling. It is. The magnetic field produced by the magnet generates an audible frequency signal combined with a slow ramp signal. modulated by the signal. This audio-frequency signal is passed to a phase-sensitive detector. Supplied. The reflected electron spin resonance signal (ESR) from the circulator is , detected and amplified by a special amplifier, which detects the ESR signal by phase-sensitive detection. This detector detects the phase-matched and phase-sensitive characteristics fed to the detector. Removes noise by amplifying only the ESR signal at a certain audio frequency . This amplifier uses a signal that varies with the detector current to be used by the microphone. Also supplies a single board computer that controls the output frequency of the radio wave source . The computer is connected to an input keypad and an output display means. and provides an output signal that tunes the matching circuit. This system is fully developed is automatic and can be performed by humans with very limited training. It can be operated to accomplish the following. In the end, all that is required of the operator is to bring the sample into resonance. place in the display device, request the desired readout on the keypad, and display the It's just a matter of recognizing the desired output above.

Brief description of the drawing The present invention will be more clearly understood by referring to the following detailed description of the invention and the following drawings. be understood.

Figure 1 shows the system block of an electron spin resonance spectrometer (ESR3) according to the present invention. This is a schematic diagram.

FIG. 2 is an overall view of a permanent magnet assembly that may be used with the system of FIG. .

FIG. 3 shows an overall strip gap resonator that can be used with the system of FIG. It is a diagram.

FIG. 4 is an overall diagram of an impedance matching structure used with the system of FIG. Ru.

4A is an enlarged view of the portion indicated by circle A-A in FIG. 4. FIG.

FIG. 5 is a schematic diagram of another form of resonator that may be used with the system of FIG. 1.

FIG. 6 is a schematic diagram of yet another form of resonator that may be used with the system of FIG. Ru.

Figure 7 shows a type of remote sensor that can be incorporated into the system of Figure 1. FIG.

Detailed description of the invention In Figure 1, a suspected drug containing a specific reagent detectable by ESR is shown. blood or urine, solid objects such as credit cards whose authenticity you want to confirm, jewelry you want to authenticate , or a sample whose age you wish to measure is placed in the sample chamber 10, and then Here, it is exposed to a strong magnetic field from the permanent magnet 12. The magnet 12 has a magnet in its vicinity. The magnet has a coil 14 wound around the pole piece, the pole piece having 3.　5kH An alternating current of frequency 2 is supplied. This 3.5kHz current is applied to the reference oscillator 16. from this 3.5kHz current and a single board computer 20. It is supplied to an adder circuit 18 which adds the supplied ramp signal. The lamp signal is Always slow, repetition rate on the order of 1 minute has. Therefore, the permanent magnet will absorb the lamp and the 3.5kHz combined signal. produces a magnetic field that is modulated by

The permanent magnet assembly 12 is shown in FIG. 2 and includes a permanent magnet tailpiece 13. and air gap to accommodate various sample chamber configurations. The steel yoke 11 includes an adjustable permanent magnet member 15 and a steel yoke 11. . Each of the tail bead 13 and the magnet member 15 provides a more uniform magnetic field. Covered by amorphous iron (Metglas) pole piece 17.19 with the role It includes a cylindrical member of permanent magnet. Members 13 and 15 each have the modulation described above. It supports a copper wound coil 14 which provides a magnetic field ramp signal. Magnet member 13. 15 and pole pieces 17, 19 are approximately 2 inches in diameter and the entire assembly 12 is approximately 2 inches in diameter. At approximately 5 square inches, this magnet assembly is non-standard for ESR applications. It is always small and produces a magnetic field with a width of 700 Gauss.

In addition to being a container, the sample chamber 10 is a microwave resonator and is preferably In a new form, it includes a specially made 311 crystal cylinder. However, if there is a sample inside It can be a coiled helix or a flat coil. For samples suspected of containing drugs In this case, the chamber is preferably very small with a thickness of 1-5 micrometers on the surface. A crystal similar to the examiner in which a silver circumferential ring 21 is placed leaving a small gap. a strip gap resonator containing a vessel (see FIG. 3). The circumference of this resonator The wave number depends on the diameter of the tube and the width of the gap G, and is determined as follows.

fo = 0.79 0.66rG+7.69/rD+6.46v'G/v'D where fo is the resonant frequency in GHz and G is the gap in millimeters. The width of the pipe, D, is the outside diameter of the tube in millimeters. The resonant frequency is the metal depot It is relatively insensitive to the height L of the jet 21. I know that. Gap G can be adjusted if desired or by adjustable cam 23. Therefore, if the width can be changed, it can be formed as two or more physical gears. can be done. The different gap widths are generally It is also easier to create.

The microwave generator can be a solid state oscillator, shown at number 22, to the computer 20 via line 24 to produce a GHz microwave output. Therefore, rice is controlled! Pulled. This is used in most ESR systems. This is different from the normal frequency of about 9 GHz. One reason for the 2GHz frequency is , when using samples containing water, the absorption of microwave energy is limited at this frequency. This is lower than 9GHz. The output of the microwave generator 22 is 3 ports. The output is given to port 1 of the circulator 26 of the to the matching circuit 30 used to adjust the coupling of the sample into the sample chamber 10. from port 2 through microwave conduit 28, which may be an axial cable. . Some microwave energy is passed through conduit 28 to the circulator. reflected back and the circulator passes it through port 3, preferably at zero bar. It is sent to a detector 32, which is a Schottky diode from Iass. This diode is For example, 31 East Hanover, New Chassis, 01936, USA. Farinella Drive's Triangle Made by Microwave It does not require an artificial mismatch to bias the detector, and Therefore, even greater sensitivity can be obtained as a result.

The sensed signal is fed to an amplifier 34, which signals the detector current. to the single-board computer 20, where the current flows as discussed below. Used for frequency control to the microwave generator 22 and coupling control. Ru. Amplifier 34 also outputs a voltage which is then supplied to phase sensitive detector 36. Amplify the electron spin resonance (ESR) signal. Amplifier 34 further includes detector current and E It includes a filtering circuit that filters both the SR signal and the SR signal.

The phase sensitive detector 36 is referenced to the 3.5 kHz oscillator signal and oscillator signal, and increases the portion of the ESR signal that is in phase with the reference oscillator signal. Width. This same reference signal is used to modulate the magnetic field around the sample chamber. so that any ESR sensing material produces an output signal based on this reference signal. . Most noise components of the ESR signal are rejected by the phase sensitive detector.

This is because those elements are not related to the 3.5kHz reference signal. application Phase-sensitive detectors that people consider satisfactory are rke l ey Evans Electronics Model No. , 4110.

Matching device 30 directs microwave energy into resonator or sample chamber 10. The combination is shown in more detail in FIG. Coupling loop 38 shares energy. impedance matching is provided between the coupling loop 38 and the resonator. initially mechanically adjusted by fixing the appropriate distance. to software The computer 20 controls the frequency of the microwave generator 22 to The frequency is set to correspond to the frequency of the chamber 10. The computer then amplifies Based on the value of the detector current received from the detector 34, it is determined whether a matching adjustment is necessary. make a decision If it is necessary, the detector An analog signal is passed through line 39 to matching device 30 while monitoring the current. Sent. The varactor diode 40.42 (Fig. 4) is therefore impedance matching is maintained without operational intervention. Ru. This process slightly affects the frequency of the sample chamber 10, so that the frequency be adjusted. The frequency adjustment and matching adjustment are repeated sequentially to obtain the desired detector current. Iterates until the minimum value is achieved. The reflected power is transferred to the circulator 26 and is rectified by the detector diode 32.

Other known types of resonant structures that may be used in conjunction with Applicant's system The well-known helical resonator [R, H, Webb, Rev, Sci, In5 t, 33.732-737 (1962); F, Vo■ ino, F, C5akvary, and P, 5ervoz-Gavi n, Rev, Sci, In5t39.1660-166T (August 196, H 1 Flat coil resonator by Nishikawa et al. [H, NiN15hika, H , Fujii, and L, J.

Berliner, J., Magn, Re5on, 62.79-86 (1985)]. All three resonant structures are microscopic at the sample location. It has the purpose of concentrating the wave magnetic field, and thereby Thus, the sensitivity is improved in proportion to the quality factor of the structure Q.

Figures 5 and 6 show flat and helical resonators, respectively. spiral theory The resonant frequencies and quality factors are given in Volino et al., supra. However, no reliable theory has been developed for flat coils.

According to our own original work on the latter structure, f0 near, 5F /(L+0.570), where fo is the resonant frequency in GHz, The scale and D are in centimeters and are shown in FIG. F is empirical A correction factor that depends on the quantity G and approaches 1 as G approaches zero. full auction Variations in the fo of the turbes are achieved by spreading the legs of the flat coil structure. Therefore, this structure is easily tuned.

As discussed above, the amplified detector current from amplifier 34 is 0. Depending on the polarity and magnitude of this detected DC signal, the computer The controller sends a signal along line 24 to correct the frequency of microwave generator 22. do. Computer 20 is an Octa computer located in Westminster, Colorado, USA. Made by Gon Systems' Model 5BS-2300 It is a commercially available single-board computer. This computer is an analog large A small flat panel that displays operator instructions and test results using a knife and output. Drives the panel display.

The ESR signal from the phase sensitive detector 36 is received by a computer for verification testing. This voltage is used to determine whether the signal is appropriate for the purpose. Computer 20 is a normal computer. includes a lock, but provides a long-term ramp voltage to the summing circuit 18, and provides a flat Provides output to a panel display.

As mentioned above, one application of ESR technology is to detect the presence and flow of crude oil at the bottom of the hole. It is to judge the turn. This includes a remote sensor as shown in Figure 7. The magnet 12, the coil 14, the alignment device 30, and the A structure similar to that of Figure 1, including a suitable resonant structure such as that shown in Figure 6. I am using it. FIG. 7 shows an NS magnet with a magnetic field modulated by a coil 56. A resonant structure in the form of a helix 50 located between the members is shown. Shown in Figure 4A An alignment device 58 similar to or similar to that described above is inductively coupled to the helix 5o. Ru. Matching device 58 connects conductor 39 and port 2 of circulator 26 with a coaxial cable. The coil 56 is connected via a conductor 60 to the controlled current source 18. connected through. Coaxial cable 28 and lines 39 and 60 are connected to the bottom of the oil well. It needs to be very long, on the order of several thousand feet, to reach the desired location. the Because of their length, it is necessary to include an amplifier in the line to support the signal. sell. The sensor or probe described above is equipped with a coaxial cable suitable for dropping into the oil well. Very small housing attached to cables including cables or lines 39 and 60 can be installed in the This device allows the crude oil itself to pass through this housing. No. 4,560,663 to N1cksie, 5tarke. A signal is provided indicating the presence of asphaltene free radicals as described in No. . For tracking subsurface flows, the method described in U.S. Pat. No. 3,993,131 Add the spin-labeled compound (SL) at the first position as follows. Then, the presence of oil containing SL can be detected at another location using the above-mentioned probe. It turns out.

The above-described embodiments of the invention are merely illustrative of its principles and should not be construed as limitations. It's not something that should be done. For example, the 2GHz microwave frequency mentioned above is 9G, a water-based liquid whose specific structure is useful for analyzing blood and urine For the more commonly used frequencies in the Hz range, energy is absorbed. It is explained above that it is useful because there is no such thing. Depending on the sample used, up to Frequencies between 34 GHz can be used. As understood by those skilled in microwave technology, Although such changes would cause parts of the hardware to change, as There is no change in functionality. Although other changes and modifications will occur to those skilled in the art, the specific The present invention is not limited to the embodiments. The technical scope of the present invention also covers equivalents thereof. Defined solely by the scope of the claims included.

~ ~ abstract Electron spin resonance spectrometers dedicated to specific and narrow tasks are becoming smaller and typically Compared to ESR spectrometers in laboratories, this is easily portable and easy to test. It is possible to take it to various sites to perform various tasks. This spectrometer is Much smaller magnetic structure and self-contained single-board computer and a microwave source that can be adjusted by the computer. microphone The radio wave source operates in the 2 GHz range and is matched through the circulator (26). The matching circuit connects the microwave signal to the magnetic structure. Inductively coupled to a sample chamber/resonator (10) placed in a magnetic field. oscillator (16) is an audio frequency signal combined with a slow ramp signal from a computer. modulate the output of the magnet structure. From the sample chamber/resonator (10) The reflected energy is sensed and a feature separates the detector current and ESR voltage signals. The current signal is fed to another amplifier (34), which controls the microwave frequency. the ESR voltage to a phase sensitive detector (36).

Claims (1)

[Claims] 1. An electron spin resonance spectrometer for detecting at least one property of a sample, the , a chamber comprising said sample and coupling means inductively coupled to said resonator and spaced therefrom; A sounder and a circulator connected to the coupling means; and a microwave injected into the circulator. a microwave source for providing radiation, the circulator providing microwave radiation; directing the radiation toward the coupling means and receiving a microwave spin resonance signal from the coupling means. a microwave source that receives the microwave spin resonance signal from the circulator; a detector connected to receive the signal; means for generating a substantially uniform magnetic field around the sample; and a reference oscillator; means for generating a ramp signal; connected to receive the reference oscillator signal and the ramp signal; amplifier means connected to said detection means for producing a composite signal modulating said magnetic field; to receive the spin resonance signal from the oscillator and the output from the reference oscillator. a connected phase sensitive detector; and output means responsive to the output of said phase sensitive detector. , an electron spin resonance spectrometer. 2. The electron spin resonance spectrometer according to claim 1, wherein the spectrometer comprises a computer. a keypad input means and display means connected to the computer; the phase sensitive detector provides output to the computer and the phase sensitive detector provides an output to the computer; The computer is an electron spin resonance spectrometer that generates the lamp signal. 3. An electron spin resonance spectrometer according to claim 1, wherein an impedance matching method is used. a coupling loop physically positioned at a desired distance from the resonator; A varactor connected between the loop and the circulator. reflection from a matching circuit including a diode and the matching means connected to the matching circuit; The reflected power is varied by varying the signal to the varactor diode in response to the reflected power. means for minimizing the power generated by the circulator; Spin resonance spectrometer. 4. 2. The electron spin resonance spectrometer according to claim 1, wherein the resonator has a substantially circular shape. a cylindrical quartz member interrupted on its surface inductively coupled to said loop; (interrupted) Strip with crystal member with metal ring Electron spin resonance spectrometer, which is a gap resonator. 5. 4. The electron spin resonance spectrometer according to claim 3, wherein the resonator has a substantially circular shape. a cylindrical quartz member interrupted on its surface inductively coupled to said loop; (interrupted) Strip with crystal member with metal ring Electron spin resonance spectrometer, which is a gap resonator. 6. 4. The electron spin resonance spectrometer according to claim 3, wherein the resonator Electron spin resonance spectrometer, which is a helical member inductively coupled to a loop. 7. 4. The electron spin resonance spectrometer according to claim 3, wherein the resonator is a flash An electron spin resonance spectrometer is a two-coil resonator. 8. 2. The electron spin resonance spectrometer according to claim 1, wherein the resonator has a substantially circular shape. It is a cylindrical crystal member and includes a crystal member having a metal ring plated thereon. a strip-gap resonator, the ring having a height that is actually lower than the height of the cylinder. qualitatively short and with a height parallel to the height of the cylinder, and by means of a narrow gap the ring The area is designed so that it does not cover the area completely. a matching loop connected to the circulator and inductively coupled to the resonator; physically positioned at a desired distance from the metal ring, the resonator and the circular Electron spin resonance spectrometer that substantially matches the impedance between the laser and the electron spin resonance spectrometer. 9. The electron spin resonance spectrometer according to claim 8, wherein the varactor diode a matching circuit comprising: connected between the circulator and the loop; Means responsive to reflected power from the circuit include a signal to the varactor diode. An electron spin resonant spectrometer that varies the signal to minimize the reflected power. 10. An electron spin resonant spectrometer according to claim 1, wherein the magnetic means comprises: a pair of permanent magnets placed in fixed relation to each other, with opposite legs supporting said magnets; A U-shaped iron frame and the magnet made of amorphous iron are adjacent to each other. a pole piece on a section and a torus-shaped (tor) surrounding at least one of said permanent magnets; an electron spin resonant spectrometer comprising: a lamp modulating coil; 11. 11. An electron spin resonance spectrometer according to claim 10, wherein the adjustable means An electron spin resonance spectrometer is provided that varies the spacing between the magnets. 12. 12. The electron spin resonant spectrometer according to claim 11, wherein the magnetic pole piece and the The magnet is less than approximately 3 inches in diameter and the magnetic means is approximately 5 square inches in diameter. Electron spin resonance spectrometer not exceeding . 13. 4. An electron spin resonance spectrometer according to claim 3, wherein the magnetic means comprises: a pair of permanent magnets placed in a circumferential relationship with each other, and opposite legs supporting said magnets; A U-shaped iron frame and the magnet made of amorphous iron are adjacent to each other. a toroidal ramp variable surrounding at least one of said permanent magnets; An electron spin resonant spectrometer comprising a tuning coil. 14. The electron spin resonant spectrometer according to claim 1, wherein the microwave source An electron spin resonance spectrometer in which the ion beam produces a radiation frequency of approximately 2 GHz. 15. The electron spin resonance spectrometer according to claim 3, wherein the microwave source is an electron spin resonance spectrometer that produces a radiation frequency of approximately 2 GHz. 16. The electron spin resonance spectrometer according to claim 1, wherein the reference oscillator comprises: Electron spin resonance spectrometer producing a reference frequency of approximately 3.5kHz. 17. 4. The electron spin resonance spectrometer according to claim 3, wherein the reference oscillator comprises: Electron spin resonance spectrometer producing a reference frequency of approximately 3.5kHz. 18. An electron spin resonance spectrometer that detects at least one property of a sample. hand, magnetic means for producing a magnetic field to which said sample is exposed; and associated with said magnetic field means. coil means connected to said coil means for producing a signal modulating said magnetic field; a quasi-oscillator; a circulator, a microwave source, the circulator and the sample connected together; a matching circuit connected to a resonator disposed therein, the resonator being is inductively coupled to the matching circuit, connected to the circulator and connected to the matching circuit; a detector that receives a modulated micro-He signal from the circuit; amplifier means connected to said detector; a phase sensitive detector connected to said reference oscillator and said amplifier means; and a keypad. , display means; an amplified detector current from said amplifier means and a resonant signal from said phase sensitive detector; a frequency signal to the microwave source and an input from the keypad; a microphone to the resonator by providing a control signal and an analog output to the matching circuit; Combining the radio wave energy and the magnetic field lamp output signal to the adder circuit and the output of the spectrometer. a connected computer to adjust the output to a display means for displaying the data means; Electron spin resonance spectrometer equipped with 19. The electron spin resonant spectrometer according to claim 18, a coupling loop, the coupling means being physically positioned at a desired distance from the resonator; a varactor diode connected between the loop and the circulator; a matching circuit and responsive to reflected power from said matching means connected to said matching circuit; In response, the signal to the varactor diode is varied to maximize the reflected power. and means for miniaturizing an electron spin resonance spectrometer connected to said circulator. . 20. 19. The electron spin resonance spectrometer according to claim 18, wherein the spectrometer comprises a computer. a computer, a keypad input means and a display hand connected to the computer; a stage, the phase sensitive detector providing an output to the computer; The computer is an electron spin resonance spectrometer that generates the ramp signal. 21. An electron spin resonance spectrometer according to claim 1, wherein the magnetic means comprises: a pair of permanent magnets placed in fixed relation to each other, with opposite legs supporting said magnets; A U-shaped iron frame and the magnet made of amorphous iron are adjacent to each other. a pole piece on a section and a torus-shaped (tor) surrounding at least one of said permanent magnets; an electron spin resonance spectrometer comprising: a lamp modulation coil; 22. 19. The electron spin resonance spectrometer according to claim 18, wherein the microwave between the matching circuit and the circulator; and between the matching circuit and the circulator. The connection to an electron spin resonance spectrometer is a coaxial cable. 23. a microwave circulator and a microphone providing radiation to said circulator; A chroma wave source, a detector connected to the circulator, a reference oscillator, and a run. a computer comprising means for generating a ramp signal; amplifier means for jointly generating a composite signal, connected to said detector and said reference oscillator; a phase-sensitive detector connected to the microcontroller, and a phase-sensitive detector receiving the output of the phase-sensitive detector; the computer operative to control the output frequency of the wave source; and the spectroscopy detecting at least one property of a sample, including means for displaying the output of the instrument; a resonator and exposing the sample to the resonator for use with an electron spin resonance spectrometer; a remotely operated probe including means for emitting a substantially uniform magnetic field around said sample; a permanent magnet means fixed to said permanent magnet means and receiving said composite signal; a winding connected to tilt and modulate the magnetic field; inductively coupled to the resonator, connected to a middle port of the circulator; , the connection comprises a coaxial cable, a microwave matching device and the matching device. connecting the matching device to the microwave device and connecting the matching device to the microwave device. means for tuning to the desired output signal of. 24. 24. A remotely operated probe according to claim 23, wherein said amplifier means comprises a first 1 long conductor to the computer and the matching device to the computer. The means for connecting to a computer includes a second elongated conductor, and the coaxial cable is substantially equal in length to the first and second elongated conductors; and probes that are isolated from each other and from the environment. 25. 24. The remote control probe of claim 23, wherein the probe is a housing, the outer housing having a port for receiving liquid sample material; probe. 26. 24. The remote control probe of claim 23, wherein the probe is a solid state. A probe that includes an operation for receiving sample material.