SU1423949A2 - Apparatus for separating signals in electron paramagnetic resonance spectrometer - Google Patents

Abstract

The invention relates to a technique of electron paramagnetic resonance, can be used in the instrument-making industry in the manufacture of EPR radio spectrometers and is additional to the author's certificate No. 1078300, the purpose of the invention is to increase the sensitivity and reduce the complexity of tuning the spectrometer when the number of storage channels changes. An adjustable voltage source is introduced into ycTpovlcTBO, and the digital-to-analog converter is multiplied, and the output of the adjustable voltage source is connected to the input of the reference voltage, digital-to-analog converter. In each period of the low-frequency sweep of the magnetic field, the average value of the signal realization is corrected in accordance with the specified number of storage channels, 1 slug. (About ate

Description

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with

NU

with

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The invention relates to an electron paramagnetic resonance (EPR) technique and can be used in the instrument-making industry in the manufacture of EPR radio spectrometers.

The purpose of the invention is to increase the sensitivity and reduce the complexity of setting up the spectrometer.

The drawing shows a diagram of the device.

The device contains an electromagnet 1, a power source 2 with a low-frequency scanning unit, a high-frequency modulator 3, a resonator 4, a microwave unit 5, a selective amplifier 6, a synchronous detector 7, an analog-to-digital converter (ADC) 8, a digital storage device 9, a divider 10 frequency, reversible counter 11, buffer register 12, multiplying digital-to-analog converter (D / A converter) 13 I adjustable voltage source 14

Ensuring the compensation of the level of the zero line of the spectrum when changing the 1 number of channels of the accumulator is based on the correction of the control voltage; accumulated by a given number of channels (chapter I The signals in the proposed device are distinguished as follows, i Electromagnet 1 creates a polarizing magnetic field, the low-frequency 1 inversion of which is carried out by the power source 2 with the low-frequency sweep unit, and the high-frequency modulation of the magnetic field 3. Resonator 4, placed between the pole tips of the electromagnet 1, is connected to an ij: oM 5 microwave, in which the signal due to the EPR is detected by the microwave detector, from which the output is removed from the | modulation frequency. This signal is amplified by selective 51 silica gel 6 and synchronized tfbiM detector 7 is detected. A second control voltage is applied to the second input of IfOHHoro detector 7 detector, carrying out a proportional displacement of the initial level at the output of the synchronous detector Tiopa 7 Then the low-frequency signal PR is converted to the ip code 8, which is synchronously summed by the digital memory 9.

ADC 8 has two outputs. The number N and | mpulsov on the second output 15 ADC 8, k | ak and in the prototype, during one

the sweep of the magnetic field is equal to the number of channels of the storage device, i.e. N7.

The number N of pulses arriving at the summing input of the reversible counter 11 through a frequency divider 10 with the counting module 2 ™ from the first output 16 of the A / D converters 8 during the time of one sweep is determined by pressing

N (.Om / 2 -,

ADC where m is the ADC resolution 8;

 quantization step ADC 8; whether - the shift of the average value of the output signal of the synchronous detector 7 during one sweep relative to the midpoint of the dynamic range of the ADC 8.

As a result, the state of the reversible counter 11 during the time of one sweep will change by

„„ And 1

Nf- -. CPU

l u

Reverse Counter Content

11 is overwritten into the buffer register.

12 at the end of each sweep of the magnetic field. The digital code recorded in register 12 is converted by multiplying the DAL 13 into the corresponding voltage.

The output voltage of the multiplying DAC 13, generally defined by the expression

 U

and

yal

K-Upn-FCt)

l u

where K - transfer coefficient (function code);

Up, is the reference voltage; F (t) is the function of changing the reference

stress

. is supplied to the control input of the synchronous detector 7 by shifting its initial output level by

c "„ ly-bc „„ - P (s)

di ji "i x n atsp

l u

-f ™ -F (t),

where bsdn is the quantization step of the DAC.

The change function F (t) of the reference voltage is set by the adjustable voltage source 14 in the form

F (t) y. Thus, we finally have

 -lU

h hmp

h7

I

2 "n-i

r - A-dU,

 "CPU

where A is a constant

The result shows that at the moment; the beginning of each sweep of the magnetic field, the initial offset of the output voltage of the synchronous detector 7 varies in a jumpy manner by an amount uniquely determined by the offset 4U of the average output value of the synchronous detector 7 during one sweep of the magnetic field relative to the midpoint of the dynamic range of the ADC 8 and is independent of the number t storage channels. The latter circumstance provides automatic compensation for the offset of the zero line of the input signal of the A / D converter 8 when the number of channels of accumulator 9 changes and thus reduces the tuning time of the spectrometer and the search for spectral lines by an average of 20-30%. In addition, the narrowing is dynamic 1423949

The range after the detection of the detector makes it possible to more efficiently use the storage space of the storage device and, consequently, to increase the sensitivity of the spectrometer.

Claims (1)

Invention Formula I Signaling device in the spectrometer of electron paramagnetic resonance on av.ev,. No. 1078300, characterized in that, in order to maintain sensitivity and reduce the complexity of adjusting the spectrometer when the number of storage channels changes, an adjustable voltage source is additionally introduced, and the digital-to-voltage converter is multiplied, the output of the adjustable voltage source is connected to the input voltage of the analog-digital converter and its control input is connected to the second control output of the accumulator.