SU1467475A1 - Method of recording spectrums of nmr of magnetically-ordered substances - Google Patents

Abstract

The invention relates to the field of the study of substances using nuclear magnetic resonance (m) and is intended to study the US method of new echo of magnetically ordered substances in the presence of a domain structure in them. The aim of the invention is to increase the reliability and accuracy of recording spectra by allocating spin echo signals from domains from a superposition of intra-boundary and intra-domain signals. The goal is achieved by the fact that when a spin-echo signal is excited by a sequence of two radio-frequency pulses, a short strobe pulse is set on the slope of the spin-echo signal envelope to the right of the max iyum at a distance D t. selected from the condition TG% 4.t.Tf, where ıTG is the effective relaxation time of the nuclei in the domain boundaries and domains, respectively, and the NMR spectrum is recorded using the spin echo signal excited in the domains. 3 il. Vfacfia 22Sifc

Description

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The invention relates to the field of research of substances using nuclear magnetic resonance (NMR) and is intended to be studied by the spin-echo (SE) method of magnetically ordered substances (MUV) in the presence of a domain structure.

The purpose of the invention is to increase the reliability and accuracy of the registration of the spectrum by allocating spin echo signals from the domains of the cynej position of the boundary and intradenomal signals.

FIG. Figure 1 shows the echo signal and strobe pulse for a CdCrgSe sample;

fig 2 - recording a wide component of the spin echo signal on one

(Frequency; Fig. 3 - recording echo signals at different frequencies ..

Example. To register the NMR spectra of the intradomain nuclei, the CsYug sample is placed in the circuit of the high-frequency pulse generator of the NMR spectrometer and the sample is subjected to two excitation pulses of the same amplitude U

100 V, the durations of the first t 4 ISS, the second t 8 ISS and delayed relative to each other for a time interval f 100 µs (for

Ql

,:

  1800 X, X and T, the effective relaxation time of the nuclei, respectively, at the domain boundaries and within the domains) and the frequency of excitation pulses equal to 44.6 MHz. The echo signal at this point of the spectrum corresponds to that shown in FIG. 1. Moving the strobe pulse around the oscilloscope screen, install it on the wide component of the echo signal, to the right of Max 1um at distance nsh-1 ut 7 X. Then, the 5MP der Cr spectrum is recorded as a function of the amplitude of the wide component of the echo signal from the frequency of the excitation pulses. The NMR spectrum of intradermal SISGs Ze is depicted in FIG. 2..

Fig. 3 shows the echo waveform observed at frequencies 43.2; 44.3 and 45.2 MHz, corresponding to the excitation of the echo signal only within the domain boundaries.

Additional analysis of the NMR spectra of der Cr using the angular dependence of the lines of the NMR spectra of a single single crystal in the saturated. The magnetic field of the magnetic field shows that the NMR spectrum of der Cr, given by the method proposed, reflects the echo signals of only the intradomain der. I

Formula of invention

The method of recording NMR spectra of magnetically ordered substances, including the impact of a high-frequency magnetic field on a sample at a resonant frequency in the form of a sequence of two pulses delayed relative to each other for a time interval S, recording a spin echo signal, inserting a strobe pulse within a spin echo signal and recording the NMR spectrum characterized in that, in order to increase the reliability and accuracy of the recording of the spectra by allocating spin echo signals from the domains of the superposition of the boundary and internal the tri-domain signals, a strobe pulse with a duration of 1 µs ± + 10% is set on the slope of the envelope of the spin echo signal to the right of the maximum at the distance and t chosen from the condition T dt i T, where the effective relaxation time of the nuclei, respectively, in the domain boundaries and inside the domains and the NMR spectrum is recorded using a spin echo signal excited in the domains.

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Editor N. Bobkova

Compiled by V. Mayorshin

Tehred M. Didyk Proofreader L. Pilipenko

Order 1189/41

Circulation 788

VNII1SH of the State Committee for Inventions and Discoveries at the State Committee on Science and Technology of the USSR 4/5, Moscow, Zh-35, Raushsk nab. 113035

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Subscription

Claims (1)

SUMMARY OF THE INVENTION A method for recording NMR spectra of magnetically ordered substances, comprising exposing a sample to a resonant frequency with a high-frequency magnetic field in the form of a sequence of two pulses delayed relative to each other for a time interval t, recording a spin echo signal, introducing a strobe pulse within the spin echo signal and recording the spectrum NMR, characterized in that, in order to increase the reliability and accuracy of the registration of spectra by isolating the signals of the spin echo from domains from a superposition of boundary and intradomain signals, a strobe pulse of 1 μs + + 10% duration is set on the slope of the envelope of the spin echo signal to the right of the maximum at a distance & t selected from the condition I <Т, where and the effective relaxation time of the nuclei, respectively, in the domain walls and inside domains, and the NMR spectrum is recorded by the signal of the spin echo excited in the domains. Fig.Z