SU873079A1 - Electron paramagnetic resonance (epr) spectrometer - Google Patents

Description

one

The invention relates to the technique of electron paramagnetic resonance (EPE) and can be used in radio engineering and other industries in the manufacture of EPR spectrometers.

EPR spectrometers are known in which an automatic frequency tuning (AFC) system is used to eliminate the slow changes (drift) of the source frequency, microwave frequencies, comparing the frequency of the microwave source with the tuning frequency of the measuring resonator 1.

However, such spectrometers do not allow recording of the dispersion signal. these in the usual way. Moreover, the AFC system on the measuring resonator becomes ineffective as the power delivered to the detector decreases.

The closest in technical essence to the proposed is an EPR spectrometer containing a microwave generator stabilized by a reference resonator, having a frequency correction device, a measuring resonator with a magnetic modulation loop and an ampoule for the sample, and the reference and measuring resonators are in the form of a single unit, have the same shape and size, are made of the same material, the circulator connected to the microwave generator, the measuring resonator and the EPR recording unit, the magnetic modulator ol, coupled to the measuring loop resonator 2 modulation.

ten

However, during the operation of this spectrometer, due to the inevitable heating of the measuring resonator by modulation elements, the tuning frequency of the measuring resonator changes in relation to the frequency of the reference resonator. This reduces the stability of the spectrometer and requires an additional periodic adjustment frequency adjustment operation.

20 measuring or reference resonator.

The aim of the invention is to increase the stability of the EPR spectrometer at low microwave power in a measuring resonator.

The goal is achieved by the fact that in an EPR spectrometer containing a microwave generator, stabilized by a reference resonator having

30 a frequency correction device, a measuring resonator with a magnetic field modulation loop and an ampoule for a sample, the reference and measuring resonators made as a single unit, have the same shape and dimension, are made of the same material, the circulator connected to the microwave generator, the measuring resonator and the EPR signal recording unit, a magnetic field modulator associated with the modulation loop of the measuring resonator, the reference resonator has a heater connected to the magnetic field modulator identical to th loop modulation measuring resonator.

The block diagram of the proposed spectrometer is presented.

The spectrometer contains a microwave generator 1, a reference resonator 2 with a heater 3 and a frequency correction device 4, a measuring resonator 5 with a modulation loop b and an ampoule for sample 7, a magnetic pulse modulator 8, a circulator 9, and an EPR 10 signal recording unit.

The microwave power from the microwave generator 1, stabilized by known methods of the reference resonator 2, enters the measuring resonator 5 through the circulator 9, and then, reflected from it, via the circulator 9 enters the ESR signal registration unit 10. When changing using the correction device 4, the tuning frequency of the reference resonator 2 is adjusted to the frequency of the measuring resonator 5. Since the location of the test sample 7 using modulator 8 and loop 6 implies a slight modulation of the resonant magnetic field, and POWER)

The microwave reflecting from the measuring resonator 5 and carrying information about the EPR signal is also modulated. With a small amplitude modulation of the magnetic field under conditions of negligible heating by the modulation loop b and heater 3 of the resonators 5 -I 2 heating, their electromagnet, electronic components, etc. does not cause significant mutual tuning of their frequencies, due to the implementation of the resonators as a whole. An increase in the amplitude of the modulation of the magnetic field causes a correlated heating of the measuring resonator 5 by the modulation loop b and the reference resonator 2 by the heater3. Due to the fact that the standard 2 and measuring 5 resonators are identical in shape, size and material, and the heater is identical to the modulation loop, this heating is the same.

Thus, due to the fact that the reference and measuring resonators are made as a single unit of two resonators having close temperature frequency coefficients (identical in shape, size 5 and material) and the reference resonator has a heater (identical to the modulation loop of the measuring resonator), connected with the output of the modulator of the magnetic field, the temperature detuning of the tuning frequency of the measuring resonator relative to the tuning frequency of the reference resonator, i.e. The stability of the EPR spectrometer is improved at

5 low microwave power in a measuring resonator and large amplitudes of modulation of the magnetic field.

The use of the proposed image. Reteni is especially effective when designing compact EPR spectrometers, where temperature gradients are inevitable.

Claims (2)

1.Maron RS, Pozn to A.L. and Shushkevich S.S. Instrumentation for the study of electron paramagnetic re-. zonance. L., Energie, 1968, p. 46-84. 2. USSR author's certificate according to the application 2579925, class C. 01 N 27/78, 1978 (prototype).