SU361722A1 - Impulse spectrometer of nuclear resonance - Google Patents

Abstract

1. PULSED NUCLEAR RESONANCE SPECTROMETER, high-frequency pulse generator, receiver and heterodyne, electrically conjugated heterodyne self-tuning block, modulator and pulse driver, characterized in that frequency tuning of high-frequency blocks with an actuating mechanism.2. The spectrometer according to claim 1, about t. L., Is that, in order to automate the process of finding the signal and increasing the sensitivity, the spectrometer contains a multichannel drive, the input of which is connected to the output of the receiver.

Description

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The invention relates to nuclear resonance spectrometers and can be used to search for and detect induction signals and spin echo square, pulsed, ferromagnetic, and other resonances in order to study the physicochemical properties of a solid.

In the known NQR radio spectrometers, a frequency tuning of the spectrometer is carried out to search for unknown nuclear resonance signals, so that almost every single frequency produces many single or paired probe pulses.

An induction signal (or echo) occurs immediately after the first probe pulse or some time after the second probe pulse. The repetition of the probe pulses T (or a pair) is chosen longer than the time of the SP and the full-time relaxation T, t . T p | T, otherwise the sample is pinned, the signal amplitude decreases or the signal disappears. Signals are observed on the oscilloscope screen or recorded on a tape recorder.

The disadvantage of these spectrometers is the duration of the search signal in the frequency range, especially with a large value of T.

The aim of the invention is to reduce the search time for nuclear resonance signals.

To this end, the frequency of all high-frequency tunable blocks of the Spectrometer is rapidly hopping, so that the frequency of filling each subsequent sending of high-frequency probe pulses differs from the frequency of previous probe pulses by the width of the spectrum of these pulses. The period of the follow-up of probe pulses is chosen so that during a time commensurate with the spin-lattice relaxation time T, the HF-and myco-generator will increase K pairs (or single) probe pulses, where

N

i.e. passed the entire subrange pH. Gd of the spectrometer rearrangement, subsequently, the repetition period of the probe pulses Tn and the search time are reduced N times.

The block diagram of the proposed nuclear resonance spectrometer is shown in the drawing.

The RF pulse generator 1 generates powerful probing RF pulses, which are fed into the loop coil with the sample. When the pulse filling frequency coincides with the sample nuclear resonance frequency, a nuclear induction signal appears. and echoes that are sensed by the pulsed receiver 2.

The accuracy of setting all tunable units of the spectrometer: generator 1 ,; the receiver 2 and the heterodyne 3 0 are provided with electromechanical coupling of the tuning elements and the operation of the self-tuning unit 4 of the pulse frequency oscillator. The modulation of the RF oscillations of the pulse generator t is carried out by the modulator 5, the formation of a pulse sequence is made by the pulse shaping unit b.

Signals At the receiver's output, when a subband passes through without accumulating, it can be observed on an oscilloscope while synchronizing its sweep at the moment when the beginning of the subband passes. When a weak signal is extracted from noise, signal accumulation using multichannel accumulator 7 is used. Signals and noise appearing in this frequency channel N of the spectrometer are output from receiver output to 0 multichannel storage 7 (each channel Nj of the spectrometer in the multichannel drive corresponds to its own channel). Switching the channels of the accumulator is performed simultaneously 5 with the reorganization of the channels of the spectrometer using the software device 8, which controls the operation of the actuator 9.

The software device 8 generates the clock pulses in such a sequence that, when the frequency section is n-times passing through the same channel of the multichannel storage device. Thus, the use of multi-channel 5 accumulator makes it possible to extract signals from noise (increase the signal-to-noise ratio), store them in memory for a long time, automate the process of searching for an unknown signal. 0 Using the software device 8 and the actuator 9, the speed of the spectrometer tuning is chosen so that the entire working

the frequency range was past and the time commensurate with the spin-lattice relaxation time T, and the output of the probe pulses was made at the time when the probe pulse filling frequency differs from the previous probe pulse filling frequency different from the frequency of the previous probe pulse the width of its spectrum (or commensurate with it).

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Thus, in this case, the known spectrometer is at least passing the subrange by N times with. The fulfillment of the construction conditions is less than in the unsaturation of the sample.

Claims (2)

1. A NUCLEAR RESONANCE PULSE SPECTROMETER, comprising a high-frequency pulse generator, a receiver and a local oscillator, an electrically coupled local oscillator self-tuning block, a modulator and a pulse shaper, characterized in that, in order to reduce the search time for a nuclear resonance signal, the spectrometer contains a program frequency tuning device high-frequency blocks with an actuator. 2. The spectrometer according to claim 1, characterized in that, in order to automate the process of searching for the signal ‘and increase the sensitivity, the spectrometer contains a multichannel drive, the input of which is connected to the output of the receiver. ™ SU, 361722