JPH02502039A - 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] electron spin resonance spectrometer The present invention relates to an electron spin resonance spectrometer.

Electron spin resonance spectrometer (ESC) also called electron paramagnetic spectrometer (EPR) is a resonant absorber of microwave radiation by a paramagnetic system placed in a magnetic field. Ru.

Applications of ESR include physics (crystals and powdered metal ions), chemistry (crystals, metal ions in solution), chemical synthesis, free radicals and chemical reactions), biochemistry (especially heme proteins, nonheme iron proteins), Contains rotin, copper protein, zinc enzymes, and proteins and cell membrane components. The use of metal substitutions such as cobalt to replace zinc by spin labeling of biomolecules containing ), natural substances (synthetic substances of coal and metals in petroleum with bonding groups and trace metals) natural occurrence of ions), gemmology (e.g. co-inventor of the present invention, Drs. Natural safa using the method developed by Hutton and Troup (Identification between ear and synthetic sapphire), glass technology (magnetic ions in glass and structural structural disorder). Others where significant development is possible Areas include free radical production testing in clinical medicine, gamma radiation foods, and archaeology. Includes inspection.

Electron spin spectrometer (ESR), often called electron paramagnetic spectrometer (EPR) is a nearly constant microwave frequency, i.e. 9 to 10 GHz, and performed on the spectrum recorded as a function of the electric field. Microwave circuits are usually It is constructed around the waveguide element and is therefore large. The exploration spectrometer weighs 1 ton. It has a magnet weighing between 3 tons and 3 tons. Therefore, the ESR spectrometer can be easily moved. Can not. It is a small branch top model that was released on the market 15 to 20 years ago. It's too heavy to move.

In recent years, low microwave frequencies (1 to 4 GHz) have been developed using copper (■) and cobalt (II). ) and molybdenum (V), and for biologically important It has been found that the sample provides improved spectral resolution.

Applications for ESR at low microwave frequencies (1 to 4 MHz,) require at least The old side spectrometer principle included in the 1941 magnetron design was introduced in 1981. It has gained effectiveness from its rediscovery and is now replacing the spectroscopic sample resonator. Described in the ESR literature as a split ring or loop gap spectrometer Ru. In its simplest form, such a spectrometer uses a resonant slit along one side. It is an introduction cylinder with. The sample volume can be measured at 9 GHz by such a spectrometer. Sensitivity approximately 2 to 3 times lower can be maintained at currently used levels. Ru. This makes it possible to achieve an ESR of 1 to 4 GHz on a normal basis. machine After being constructed of ceramic (MA COR manufactured by Corning Glass) that can Electroplated loop gap spectrometers for use in the 2 to 4 GHz range It is easily formed.

The proposed microwave bridge and ESR spectrometer are compatible with the operation of the described spectrometer. used with, but not limited to, any suitable sample spectroscopic microwave configuration. You may be

The object of the present invention is to provide a relatively low cost The purpose of the present invention is to provide a mobile spectrometer.

The present invention provides a microwave source that emits microwaves to the sample and reference arm. The surge pull arm provides radiation to the spectrometer where the sample for analysis is installed. a circulator that receives radiation from the spectrometer and directs it to the detector. and the detector detects a sample and a reference to determine characteristics of the sample. detecting said microwave radiation from said sample arm and said sample arm; Electron spin where the sample reference arm is formed as an integral microwave bridge Provide spectrometers.

Since the element is formed as an integral microwave bridge, the spectrometer is inexpensive. In addition, the elements can be included in a lightweight and easily moved package.

The spectrometer is installed from the microwave source to prevent reflected radiation from returning to the microwave source. an isolator that receives radiation from the sample and a reference arm; Some orienting divider and sample arm between the divider and circulator an attenuator placed in the reference arm between the divider and the detector. an attenuator and a phase shifter and a phase shifter placed in the reference arm between the divider and the detector. Preferably, it includes an attenuator and an attenuator. A single end or balanced mixer can serve as a detector. A preferred implementation of the invention can be connected between the sample arm and the reference arm. Examples will be explained in more detail with reference to the accompanying drawings.

FIG. 1 is a block diagram of an embodiment of the invention.

FIG. 2 is a schematic diagram showing a portion of the ESR spectrometer of FIG.

FIG. 3 is an electronic circuit diagram showing a portion of FIG. 1 along with the rest of the ESR spectrometer. Ru.

FIG. 4 is a cross-sectional view taken along line 5-5 of FIG.

FIG. 5 is a flow sheet showing combinator control of the ESR spectrometer.

FIG. 6 is a graph showing the typical output of an ESR spectrometer.

Referring to Figure 1, a transistor oscillator in a tunable resonator, if or a suitable VCO (voltage controlled oscillator) digital frequency divider and phase closed loop. The microwave source lO can be a programmable synthesizer chip using Microwave radiation is generated in the range of about 2 to 3 GHz. that radiation is reflected received by an isolator 12 that prevents the received radiation from returning to the microwave source lO. It will be done. Isolator 12 is configured such that some of the radiation is connected to sample arm 16 and reference The radiation is sent to coupler 14 which splits the radiation so that it is directed to arm 18.

Sample arm 16 includes an attenuator 20 . The attenuator consists of a magnet 24 and an adjustment coil. A microwave pulse falling onto a sample placed in a resonator 22 surrounded by Adjustable to vary the amount of power. -kinilator 30 is attenuator 22 and the sample (not shown) is volted to the radiation. radiation to the loop gap resonator 22. Next, the encoded radiation is received by a circulator 30 which directs radiation to a sensor 32.

Phase shifter 36 and attenuator 20 are implemented by a microprocessor or other computing device. A child control signal may be received on line 40 from a control device operated by.

In a first embodiment of the invention, the microwave radiation in the reference arm 18 is 42 from the attenuator 38 to the mixer 32, when it is directed from the resonator 22 to the mixer 32. radiation received by the curator 30. Output signal from mixer The number must be equipped with suitable electronic detection circuitry (not shown) to provide an output that can be analyzed. ) is a conditioned waveform that can be processed by Generally the sample All the power in the sample and reference arm is absorbed by the resonator 22. system needs to be adjusted first. When paramagnetic resonance occurs, the bridge becomes flat. The signal is received by the input of mixer 32.

Reference arm 18 allows mixer 32 to operate at the appropriate level. Its release Radiation is received from resonator 22 to effectively maximize the sensitivity of the system. Combined with radiation.

The isolator 12 and circulator 30 are striped lines or has two boats and three boats constructed using microstrive technology. It may also be a port ferrite element. The phase shifter 36 is electronically controlled. is preferable.

The resonator 22 is well known from the scientific literature and therefore will not be described in detail here. stomach.

In typical use, the magnet 24 is free electron (microwave frequency 2.5 GHz) 87 mT), which is approximately twice the field required to monitor ESR from ．． Air core Helmholtz (H) capable of linearly sweeping magnetic fields up to 15 Tesla elgholz) bare magnet, or small swept electromagnetic if mobility is not important It may be a stone. In specific applications to binding groups or nitric oxide spin labels , the magnet 24 has a field set to an appropriate value below the free electron resonance field. and above this value can be swept by the auxiliary coil 26 ( Permanent magnets (e.g. based on a 5i-Co alloy) are preferred.

Such sweeps are preferably under microprocessor or combicoater control. Delicious. No matter which type of magnet is used, the magnetic field will not exceed 100kHz. adjusted at the appropriate frequency and then adjusted to produce a spectral display. or detected by something that harmonizes with that frequency. A coil like this has approximately 30 turns. Consists of 10'/1000 gauge copper wire. Two coils are used for homogeneity Required in Mumortu state.

All elements, magnets and coils 2 separated from the resonator 22 and shown in detail in FIG. 4.28 is integrated into the microwave bridge.

A preferred embodiment of the invention is illustrated in further detail with reference to FIGS. 2 and 3. .

Input port door 0 receives microwave radiation from microwave source lO (Figure 1) . Input port door 0 is an SMA connector coupled to one of the terminals of element 12.

Element 12 has a normal design, so it will not be explained in detail, but it is a drop-in probe circuit. preferably a controller. For the second terminal of the circulator, see Figure 1. Wilkinson (Vilkins), which performs the function of coupler 14 as described in on) coupled to the divider 14. The third terminal of element 12 is connected to the circulator. Is it true that the microwave energy is reflected from Wilson divider 14 to input port 0? 50 ohm end 72 to act as an isolator to prevent radiation. Ru. A DC isolation capacitor is provided between the Wilson divider 14 and the isolator 12. 71 is connected.

Wilson divider 14 separates microwave energy from reference arm 18 and sump. received from the second terminal of isolator 12 to be directed to arm 16. Split the signal. The signal directed to reference arm 18 is received by phase shifter 3B. be believed.

Phase shifter 36 includes a first phase shifter connected to one of the arms of Wilson divider 14. It includes a circulator 73 having terminals. The second terminal of the circulator 73 is Diode support 7 supporting parallel regulating varactor diodes (not shown) 8 and a transmission line transformer coupled to a regulator 79 that adjusts the diode to parallel resonance. DC isolation capacitor 74 is coupled to converter 77 . R,F, The structure 75 operating as a chijik has D, C, bias signals R, F, and so that C can be supplied to the diode circuit in such a way that the circuit is isolated. It is composed of The signal transmission boat 2 of the circulator 73 reflects the signal. and return it to port 2, make that signal appear once on port 3, and pass through line 80. It is coupled to a responsive load consisting of a parallel regulating varactor diode. Said response load is an appropriate control to input port door 6 to change the phase of the signal appearing at terminal 3. It can be changed by supplying voltage. Third terminal of circulator 73 is coupled to microwave transmission line 80. Transmission line converter 77 is the most effective transforms line impedance to a level appropriate for ultimate diode operation .

The signal from line 80 is connected to a DC isolation capacitor 83 and a microwave transmission line. a circuit with its second terminal coupled to a PIN diode 82 via 84; is received by the attenuator 38 including the regulator 81 . Microwave transmission line 84 The other end of is coupled to a 50 ohm end 85 through a DC isolation capacitor 8B. [.

It is. Microwave transmission line 84 also receives an input current bias signal at port 8B. is coupled to bias circuitry 87 to provide . From input port 8ε current through input 89 to bias network 87 and to terminal 2 of the circulator. By properly supplying the signal, the signal received at terminal 1 will be properly attenuated. , is received at terminal 3 for supply to directional coupler 50. Directional coupler 5 0 is the transmission line type, transmitted by main transmission line 90 and port 93 Auxiliary transmission line accessed via line 91 and terminated with end 95 Contains 94. Transmission line directional coupler 50 connects to port 93 for control and monitoring. A small constant percentage of the input signal can be varied at . The transmission line 90 is coupled to a hybrid branch line coupler 101 in a general rectangular structure. including transmission line circuitry located in the The first outcaponide 104 is the branch line A second output port 105 is located at one end of the coupler 101 and a second output port 105 is located at one end of the coupler 101. It is arranged at the other end of in-coupler 101. Output port 104 is at end 1 Connected to 06. The output signal received at output port 104 is output to port 10 90° out of phase with the signal received at 5. However, some aspects of the present invention In some embodiments, a single output port may output two output signals that differ by 90 degrees in phase. It should be noted that it is not provided and can just be coupled to the transmission line 90. It is possible.

The reference arm 18 and sample arm 16 prevent electromagnetic interference between the two arms. The signals are separated by spectrum 99 for analysis.

The sample arm 1B of the spectrometer includes an attenuator 20 identical to the attenuator 38 described above. , the reference numbers used in the attenuator 38 will therefore not be described in detail here. Indicates that it corresponds to the attenuator 20. Apply a suitable voltage at input port 8B of attenuator 20. When the current is received, the signal at terminal 3 of circulator 81 is transmitted to transmission line 110. received at The directional coupler 50 is attached to the transmission line llO.

It is identical to the directional coupler 50 located nearby and installed on the reference arm 18.

The reason for the presence of the directional coupler 50 in the sample arm 16 is the coupling in the reference arm. Same as la. The microwave signal on line 110 is connected to DC isolation capacitor 12 a microwave transmission line 121 connected to its second terminal via 2; received by curator 130. The other end of line 121 into the gap resonator 22 (FIG. 1) so that the signal is received by the sample. It is connected to the coupled port 123. Radiation is radiated under paramagnetic resonance conditions. a service that directs radiation from its third terminal to the in-phase divider 124. received by the curator 30. In-phase divider 124 divides the signal. Microwave feeding signals to two ports 125 and 26 with the same phase Limited by transmission line. In-phase divider 124 is a second Wilson It is a divider.

FIG. 4 shows a cross-sectional view of a portion of the spectrometer of FIG. One of the spectrometers shown in Figure 2 The portion is formed on an aluminum base 130. Base 130 is Saki recess 1 for receiving one of the magnets 134 of a circulator such as circulator 30; 32 (only one shown). Microphone with copper layer on both sides The radio wave substrate 13B is bonded to the aluminum base 130. Board 13B is Connected to the base 130 by screws, by gluing or by introducing any suitable device. Good too. The top copper layer of board 136 follows lines 84.91.110 shown in FIG. , 121 and 124 are etched. then those lines is shown in FIG. 2 by the copper ribbon 13B or the DC isolation capacitor described above. circulator 30 and circulator 81. . In the embodiment shown in FIG. 2, three boards similar to board 138 are configured. I'm being kicked. The other two boards 137 and 139 are respectively Vida 14 and lines etched thereon 77° 80, 84 and 10 1. Although three separate boards are shown in Figure 2, a single board or It should be understood that more than two boards can be used.

FIG. 3 shows the structure shown with reference to FIG. 2 in electrical form to the left of the dotted line. It is. In Figure 3, the same reference numbers used in Figure 2 are used. .

FIG. 3 also shows the detection portion of the embodiment of FIG. 2 in more detail. Output 104, 105 , 125 and 126 are sent to two sets of balanced mixers 32 and 141. Supplied. One balanced mixer 140 is connected to the branch line coupler 101. 0'' phase shifted signal and the signal from output 125 and the other mixer is the O'' signal from branch line coupler 101 and main or sample arm 1. 6 receives the signal from output 12B from 6. The first set of balanced mixers is an audio frequency Distinguish the number-encoded signal from the microwave carrier signal. Next, from the balanced mixer 32 The output is a second set of balanced mixers 141 in which the low frequency carrier signal is separated from the sample signal. supplied to The output of the second set of balanced mixers is an analog-to-digital converter 142. , then in the signal that may be detected by monitoring the combinator system. A measurement/correction unit that is computer controlled to compensate for any changes. is supplied to circuit 144 for determining the phase difference between the reference signal and the sample signal. Ru. Squaring circuit 145 and summing circuit 149 also allow amplitude signals to be determined. A signal is received from unit 143 so that the data can be read. The square root circuit 151 also has the maximum value may be provided in any conventional form to produce. Therefore, the information received is A complete description of the E, S, R properties of the sample. Furthermore, it generates saturated transmission EPR. can include signal detection as a function of the phase and frequency of the magnetic field modulation.

Figure 5 shows a flow sheet that generally outlines the combinator control of the spectrometer. vinegar. In FIG. 5, control computer 150 is connected to the input port of the apparatus shown in FIG. - as well as controlling the voltage and current supplied to doors 8.88 and 85. Used to control microwave energy levels and magnetic field sweeps. data Acquisition combiator 160 includes a control combicoater unit and a data acquisition and communication unit. It is provided for coupling with a sample cavity resonator for signal processing. Calculation operation is The processor 170 executes in the digital signal processor unit 170, and the data acquisition The control computer 160 and the control computer 150 display information and combined with a master computer that provides power.

FIG. 6 shows as an example a typical EPR spectrum of Saphire.

The present invention uses rapid Fourier transmission in a local computer to generate spectra, etc. This is followed by using the isolator 12 and performs time dynamic ESR. The microphone of the pulse generator is inserted between the coupler 14 (FIG. 1). Includes coupling to radio wave switch. Large waveguide systems typically used at 10GHz Compact microwave circuits offer certain advantages in terms of reduced pulse drop as opposed to Should bring. What is the effective frequency range for the FFT of free induced decay? The result must be set.

In connection with electron spin echo envelope modulation studies, low frequency (and magnetic field) When analyzing frequency dependent linewidth information in regular CW ESR by using It has been shown to be effective for protons far from the paramagnetic center in the case of proteins. It is said that more acidic tests should be provided, which is due to the effect of has advantages.

Pulse mode is an active, electrically controlled simple mode that is also used for switching Can be easily implemented for quality attenuators.

Free-standing microwave bridges are compatible with any existing commercially available or specially formed microwave bridges. at a given frequency or range of frequencies for use as an accessory to an ESR spectrometer. can be generated within the

Wideband bridging efficiency is achieved using an octave bandwidth design and careful phase compensation. It should be possible to obtain

All systems considered are mobile, battery-operated and available worldwide. Can be transported anywhere.

The present invention can be easily modified by those skilled in the art without departing from the technical scope of the invention. It is understood that the invention is not limited to the particular embodiments described above, as Should.

FIG.6 Submission of translation of written amendment vf (Patent Law Article 184-8) March 20, 1989 Yoshi, Commissioner of the Patent Office 1) Takeshi Moon 1. International application number P CT/AU87100296 2. Name of the invention electron spin resonance spectrometer 3. Patent applicant Address: Clayton, Victoria, Australia.

Unillington Road (no street address) Name Monash University Representative Wade, B.B. Nationality: Australia (1 other person) 4. Agent 3-7-2 Kasumigaseki, Chiyoda-ku, Tokyo 5. Date of submission of written amendment May 9, 1988 6. List of attached documents (1) One translation of the written amendment The scope of the claims (1) Has a microwave source that emits microwaves to the sample and reference arm. The sample arm directs radiation to the resonator in which the sample for analysis is placed. It has a circulator that receives radiation from the resonator and directs it to the detector. and the detector detects a sample and a reference arch to determine characteristics of the sample. In an electron spin resonance spectrometer that detects the microwave radiation from a A microstrip micro in which the sample arm and the reference arm are integrated. A spectrometer characterized by being formed as a wave bridge.

(2) The spectrometer uses a micrometer to prevent reflected radiation from returning to the radiation source. An isolator that receives radiation from a source and that emits radiation to the sample and reference arm. A divider that directs part of the ray and a sample arch between the divider and the circulator. an attenuator located in the arm and a reference arm located between the divider and the detector. 2. The spectrometer of claim 1, further comprising a phase shifter and a second attenuator.

(3) said sample arm and front formed as an integral microwave bridge; the reference arm having a first output portion coupled to the attenuator; and the attenuator coupled to the circulator by a microwave transmission line. and said server coupled to one or more outputs by a second microwave transmission line. a second output coupled to the phase shifter; , the phase shifter includes a second circulator, and the second attenuator has a a third circulator, the second circulator being a third microwave transmitter; a fourth microwave transmission line coupled to the third circulator by a transmission line; a circulator coupling the output of the third circulator to one or more second outputs; The spectrometer according to claim 2.

(4) the sample arm includes a directional coupler, the directional coupler being a first microwave transmission line with an output terminal at one end and a termination at the other end; a fifth microwave transmission line having an end, one of the fifth transmission lines; said section so that the signal can be introduced into the fifth microwave transmission line. 4. The spectrometer of claim 3, wherein the spectrometer is arranged in close proximity to the first transmission line.

(5) The reference arm includes a directional coupler, and the directional coupler is the fourth a portion of the microwave transmission line and a sixth microwave transmission line; At least a portion of the N6 transmission line conducts the signal to a sixth microwave transmission line. arranged in close proximity to the fourth transmission line such that the fourth One end of the 6 microwave transmission line is coupled to the output and the other end is connected to the termination. 4. A spectrometer as claimed in claim 3, wherein the spectrometer is coupled.

(6) said divider includes a microwave transmission line having said two output parts; The spectrometer according to claim 3.

(7) The microwave transmission line is etched from a conductive substrate. 7. The spectrometer according to any one of 3 to 6.

(8) the one or more outputs include a pair of outputs receiving a pair of signals in the same phase; , the one or more second outputs receiving pressures having a phase that differs by 90″. 4. The spectrometer of claim 3, including a pair of signals.

(9) One output of the first pair and one output of the second pair are in a first balanced state. coupled to a mixer, the other output of said first pair and the other output of said second pair; is coupled to a second balanced mixer, said balanced mixer being connected to a second pair of balanced mixers. 9. The second pair of balanced mixers is connected to the detector. Spectrometer.゛ (10) The detector is capable of determining both absorption and dispersion properties of the sample. Determine both the phase and magnitude of the output signal received at said output so that 10. A spectrometer as claimed in claim 9, including means for:

(11) The detector includes two pairs of balanced mixers, an analog digital signal coupled to the mixers; a digital transducer, a measurement/correction unit coupled to said transducer, an absorption characteristic of the sample; a pair of square circuits and a pair of square circuits coupled to said unit so that the and a summing circuit coupled to said squaring circuit, the characteristics of the distribution of the samples being determined. 2. The method according to claim 1, further comprising a phase difference determining circuit coupled to said unit to enable said unit to spectrometer.

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Claims (11)

[Claims] (1) Has a microwave source that emits microwaves to the sample and reference arm. The sample arm directs radiation to the resonator in which the sample for analysis is placed. It has a circulator that receives radiation from the resonator and directs it to the detector. and the detector detects a sample and a reference arch to determine characteristics of the sample. In an electron spin resonance spectrometer that detects the microwave radiation from a The sample arm and the reference arm are configured as an integral microwave bridge. A spectrometer characterized by: (2) The spectrometer uses a micrometer to prevent reflected radiation from returning to the radiation source. An isolator that receives radiation from a source and that emits radiation to the sample and reference arm. A divider that directs part of the ray and a sample arch between the divider and the circulator. an attenuator located in the arm and a reference arm located between the divider and the detector. 2. The spectrometer of claim 1, further comprising a phase shifter and a second attenuator. (3) said sample arm and front formed as an integral microwave bridge; the reference arm having a first output portion coupled to the attenuator; and the attenuator coupled to the circulator by a microwave transmission line. and said server coupled to one or more outputs by a second microwave transmission line. a second output coupled to the phase shifter; , the phase shifter includes a second circulator, and the second attenuator has a a third circulator, the second circulator being a third microwave transmitter; a fourth microwave transmission line coupled to the third circulator by a transmission line; a circulator coupling the output of the third circulator to one or more second outputs; The spectrometer according to claim 2. (4) the sample arm includes a directional coupler, the directional coupler being a first microwave transmission line with an output terminal at one end and a termination at the other end; a fifth microwave transmission line having an end, one of the fifth transmission lines; said section so that the signal can be introduced into the fifth microwave transmission line. 4. The spectrometer of claim 3, wherein the spectrometer is arranged in close proximity to the first transmission line. (5) The reference arm includes a directional coupler, and the directional coupler is the fourth a portion of the microwave transmission line and a sixth microwave transmission line; At least a portion of the sixth transmission line conducts the signal to the sixth microwave transmission line. arranged in close proximity to the fourth transmission line such that the fourth One end of the 6 microwave transmission line is coupled to the output and the other end is connected to the termination. 4. A spectrometer as claimed in claim 3, wherein the spectrometer is coupled. (6) said divider includes a microwave transmission line having said two output parts; The spectrometer according to claim 3. (7) The microwave transmission line is etched from a conductive substrate. 7. The spectrometer according to any one of 3 to 6. (8) the one or more outputs include a pair of outputs receiving a pair of signals in the same phase; , the one or more second outputs receiving outputs having a phase different by 90°. 4. The spectrometer of claim 3, including a pair of signals. (9) One output of the first pair and one output of the second pair are in a first balanced state. coupled to a mixer, the other output of said first pair and the other output of said second pair; is coupled to a second balanced mixer, said balanced mixer being connected to a second pair of balanced mixers. 9. The second pair of balanced mixers is connected to the detector. Spectrometer. (10) The detector is capable of determining both absorption and dispersion properties of the sample. Determine both the phase and magnitude of the output signal received at said output so that 10. A spectrometer as claimed in claim 9, including means for: (11) The detector includes two pairs of balanced mixers, an analog digital signal coupled to the mixers; a digital transducer, a measurement/correction unit coupled to said transducer, an absorption characteristic of the sample; a pair of square circuits and a pair of square circuits coupled to said unit so that the and a summing circuit coupled to said squaring circuit, the characteristics of the distribution of the samples being determined. 2. A phase difference determining circuit as claimed in claim 1, further comprising a phase difference determining circuit coupled to said unit to enable said unit to spectrometer.