SU987486A1 - Substanse magnetic susceptibility measuring method - Google Patents

Description

The invention relates to the study of the magnetic properties of substances and can be used in measuring the magnetic susceptibility of large batches of samples and for continuously monitoring the magnitude of the magnetic susceptibility of substances under production conditions.

A known method for measuring the magnetic susceptibility of samples of substances, based on the influence of the magnetic field of the electromagnet on the subsequent sample, and determining the magnitude of the susceptibility by the magnitude of the force acting on the sample tl1.

The disadvantage of this method is the low accuracy of determining the magnitude of the susceptibility and a small class of substances whose magnetic susceptibility: the strength of which can be determined by this method.

Also known is the method of determining the magnetic susceptibility of samples of substances by changing the magnitude of the magnetic flux in the magnetic circuit of the electromagnet when the electromagnet of the sample of the substance under investigation is introduced into the gap and removed from the electromagnet 2 gap.

The disadvantage of this method is the low accuracy of determining the magnitude of the susceptibility and the small class of substances in which the magnetic susceptibility can be detected by this method.

The closest technical solution to the invention is the method Q for measuring the magnetic susceptibility of substances, including the removal of the electron paramagnetic resonance (EPR) spectrum of a reference sample, placed ti the magnetic field of the working magnet of the electromagnet, in which

15, the EPR spectrum of the test sample placed in the same electromagnet gap is also removed, and by analyzing and comparing the EPR spectra of these samples, the magnetic

20 susceptibility of the test substance 3.

The disadvantages of this method are the small type of substances, the magnetic susceptibility of which can be investigated by this method, and the long measurement time, determined by the need to remove the EPR spectra of the reference and test samples, as well as the duration

Claims (1)

30 spectral analysis. The purpose of the invention is to expand the types of investigations studied and reduce the measurement time. The goal is achieved by the fact that, according to the method of measuring the magnetic susceptibility of substances, including the removal of the EPR spectrum of a reference sample placed in the magnetic field of the working gap of the electromagnet, the sample of the analyte is placed in the magnetic field of the additional gap of the electromagnet, the shift of the EPR spectrum of the reference sample is measured magnetic susceptibility of a substance according to the formula where H is the magnitude of the magnetic field strength in the working gap of the electromagnet, corresponding to the middle of the ESR line Alon sample in the absence of sample analyte in the additional element a gap electromagnet; Hn is the magnitude of the magnetic field strength in the working gap of the electromagnet, corresponding to the center of the EPR reference sample in the presence of a sample of the material under investigation in the additional gap of the electromagnet h is the width of the working and additional gaps of the electromagnet; , c, is the magnetic permeability of the magnetic circuit of the electromagnet; is the length of the magnet core. The sequence of operations when using the method: removing the spectrum of the reference sample; installation of the sample under study into an additional electromagnet gap; measurement of the spectrum shift of the reference sample by re-recording its spectrum; calculation, magnitude of magnetic susceptibility. The drawing shows a diagram of the magnets of the ground lead of an EPR spectrometer, which registers the proposed method. The circuit consists of a two-gap rma 1 electromagnet — the main 2, which houses the sensor of a small EPR spectrometer 3 reference sample and an additional sensor 4 with sample 5 of the analyte, power supply 6 of the electromagnet, and system 7 for recording the spectrometer. The measurement of the magnetic susceptibility of substances using the proposed method is carried out as follows. First, the EPR spectrum of the reference sample is recorded. The standard can be any substance for which the EPR spectrum can be recorded, for example diphenylpycrylhydrazyl (DPPH). The midline of the EPR standard spectrum corresponds to the H field. Note that it is not necessary to take the midpoint of the spectrum spectrum as a reference point, it can be any point of the reference spectrum. After that, the investigated substance is placed in an additional air gap. If the thickness of the additional air gap is small and the sample of the analyte occupies the gap completely, then in this case the dispersion fluxes can be neglected and the redistribution of the magnetic flux in the magnetic core can be considered according to the generally accepted method. As a result of a change in the magnetic flux, a change in the magnitude of the magnetic field in the gaps of the electromagnet occurs, which leads to a shift in the reference EPR spectrum by a certain amount. By measuring the dN value, one can find the HQ and calculate the desired magnetic susceptibility by the formula, n; -C) (l) Calculations show that the ratio of the magnitude of the displacement n to the initial value of the field H for samples C; Co () is. The temporal instability of the resonant conditions of the compact spectrometer is or, which provides a measurement of Xd in the range. In the case of measuring the magnetic susceptibility of ferric chloride (tabular value -0, 5-1СГ), the magnitude of the shift "jH was 0.154E (12.3 A / m) at H 7.8286-10 A / m (according to the DPPH spectrum). Calculation of X-o at 1.5 m, h 0.2 m; / g 5 -10 gives the value - 2.4983-10, which well coincides with the table value Xo. At present, the proposed method: measurement of magnetic susceptibility has been implemented in laboratory conditions, allowing us to significantly simplify and speed up the procedure for measuring Ho and expand the possibilities of practical application of compact EPR spectrometers. The efficiency of the method is determined with, firstly, by a decrease in the number of substances under investigation, which is achieved by using an additional air gap in which the test substance is placed. This eliminates the need to register the EPR spectrum of the analyte, since the desired magnetic susceptibility can be determined by shifting the spectrum of the reference substances. Secondly, by reducing the measurement time. In the usual method of determining Xo from the spectra of the reference and test samples, the measurement time is determined, mainly , the recording time of the spectra is, depending on the recording conditions and the properties of the test substance and standard, an average of 5-10 minutes, although it may be longer (so, if the sample under study is such that voucher must be pyrylium, spectra recording will take at least an hour). In the proposed method, only the spectrum of the reference sample is recorded. And since a standard can be any substance for which the EPR spectrum can be recorded, the recording time of its spectrum can be limited (for example, DPPH) to about 1 minute. The time of registration of the lN value is determined by the repeated removal of the EPR spectrum of the standard if the sample under study has an additional gap, that is, it also does not exceed a minute. Thus, the total analysis time (for any test substance does not exceed 2-3 minutes. Thirdly, by simplifying the measurement procedure, which means that this method eliminates the procedure for analyzing the EPR spectra of the reference and test samples to calculate the number of spins N as well as the procedure for determining the g-factor. Simplification of the technique is also the possibility of using the same standard for the study of various types of substances. The listed features of the proposed method allow it to be used for measuring of the large susceptibility of large batches of samples, including continuous measurement in enterprises of the petrochemical industry, in the study of the shelf of the oceans and in geological searches of the invention The formula of the invention for measuring the magnetic susceptibility of substances, including the spectra of the electron sample of magnetic radiation the field-operation of the electromagnet, which is distinguished by the fact that, in order to ireni the type of the studied substances to increase the measurement time, the sample of the investigated substance has melted In addition to the magnitude of the field of the electromagnet, measuring the EPR spectrum of the reference one and calculating the magnetic susceptibility of the substance using the formula ih () i WV / II, - is the magnetic field strength in the working gap of the electromagnet of the reference sample in the absence of the sample the test substance in the additional gap of the electromagnet; - the magnitude of the magnetic field in the working gap of the electromagnet, corresponding to the midpoint of the EPR line of the reference sample in the presence of a sample of the test substance in the additional gap of the electromagnet; h is the width of the working and additional gaps of the electromagnet; w- is the magnetic permeability of the magnetic circuit of the electromagnet; MP - the length of the magnetic circuit of the electromagnet. Sources of information that are considered in the examination. Selwood P. Magnetochem. M., 1949, GL-. 1.. Guide to laboratory frames in physics. Ed. L.L.Gol, M., Science, 1973, pp.305-310; . Poole Ch. Technique EPR - spectroii. M., Mir, 1970, p. 543 (prototype).