SU787964A1 - Method of measuring variations of electron paramagnetic resonance and nuclear magnetic resonance spectrum - Google Patents

Description

one

The invention relates to the use of EPR and NMR for research and analysis of materials, mainly for the development and control of technological processes in various parts of the national economy.

In modern: studies and analysis of materials using the EPR and NMR methods, studies of changes in the physicochemical properties of a material under any kinetic effect on the material (irradiation, temperature changes, pressure, etc.) and the correlation dependence are carried out. between the magnitude of the effect and the change in the parameters of the spectral lines; measuring the magnitude of the effect on the material from a known correlation dependence by measuring the magnitude of the change in the parameters of the spectral lines.

The variations in the parameters of the EPR or NMR spectral lines are most often the intensity and width of lines 1.

The known methods of measuring changes in these spectral parameters are carried out by sequentially recording spectral curves on a plotter and then comparing these

curves by the overlap method, which makes it difficult to automate the process of measuring changes in the parameters of spectral lines.

5 The closest to the present invention is a method of measuring changes in the parameters of the EPR or NMR spectra by sequential measurement of changes in the Cadix parameters of the spectra:) P I; J; H

Yu NMR before and after the betrayal of the impact on the study of the study and their comparison.

The sequence is performed: by this method of operations the following:

15, after adjusting the spectrometer to record the spectrum, a spectrum is recorded with recording the spectral curve of the material under study on the plotter before the magnitude of the effect on the material is changed; after returning the spectrometer to the initial state, a change is made in the magnitude of the effect on the material; recording a spectral curve of the material at the plotter after changing the magnitude of the effect on the material; a visual analysis is made of the nature of changes in the parameters of the spectra obtained; in the presence of a change in the spectrum parameters, the measurement of the magnitude of the change using measuring instruments (ruler, compass, etc.); the obtained value of the change in the parameter of the spectrum (usually in mm) by means of the correspondence of the scale coefficients; the X axis translates into the real value of the width of the EPR or NMR spectral line expressed in units of the magnetic field or frequency, respectively, and along the if axis into the real value of AND {intensity of the spectral line, expressed in units of {Electrical tendency 2. However, this sequence of operations does not allow to obtain the values of the variation of the parameters of the spectral curves: directly during the spectrum recording, since after performing the recording of the spectrum on the plotter, it is necessary to perform operations of measuring the magnitude of the variation of the spectral parameters using a measuring tool and recalculate into real values EPR or NMR spectral lines through the corresponding. scale coefficients. Thus, the known method does not allow the processor to automate the measurement of changes in the parameters of spectral lines, which makes it unsuitable when conducting serial measurements. The purpose of the invention is to reduce the time taken to measure the parameters of the EPR or NMR spectra and to provide the possibility of automating the process of measuring the measurement of the parameters of the spectral lines of the EPR or NMR of the materials under study. The goal is achieved by sequentially, before and after a changing effect on a substance, time intervals are measured between the two moments of coincidence of the magnitude of the reference voltage (which is less than the amplitude value of the voltage) of the first derivative of the smaller of the compared EPR or NMR signals) the magnitude of the voltage of the signals etuce before and after passing them through the zero value of the first derivative. Then, the obtained time values of the :: time intervals are compared. FIG. 1 shows a functional diagram of the device; in fig. -2 time diagrams-ia formation of measured and compared time intervals. The functional diagram of this device includes the EPR or NMR spectrometer registration system 1, the comparison device 2, the command device 3, the start circuit 4, the reference voltage source 5, the exposure magnitude system 6., the time interval meter 7, the memory block 8 and the device 9 data processing. The process of measuring changes in the parameters of the EPR or NMR spectra according to the proposed method is carried out as follows. After tuning the spectrometer, the first derivative of the EPR or NMR signal is recorded. The signal of the first derivative from the output of the spectrometer registration system 1 is fed to the comparator 2. After passing the first amplitude value of the signal of the first derivative from the command device 3 by means of the circuit 4, the source 5 of the reference voltage is started up. The reference voltage, the value of which is less than the amplitude value of the voltage signal of the first derivative, arrives at device 2. At the moment of coincidence of the voltage values of the signal of the first derivative and reference voltage, the meter starts up 7 time intervals. When the voltage of the first derivative passes through the zero value, the sign of the reference voltage using devices 3, 4 and 5 is reversed, and with a new coincidence of the values of the voltage of the signal of the first derivative and the reference voltage, the meter 7 turns on. the measured time interval, which is proportional to the intensity and width of the EPR or NMR spectral line, is memorized using memory block 8. After returning the spectrometer to the initial state, the effect or the change in the magnitude of the effect on the 1Oe BeiuecTBO inheritance is made. After the cessation of exposure or the change in the magnitude of the effect on the substance, the duration of the time interval, proportional to the intensity and width of the spectral line, is measured. With the help of devices 3, 8, and 9, the obtained values of the durations of the time intervals are compared and the magnitude of the change in the parameters of the EPR spectra or CNR as a result of the action or change in the magnitude of the effect on the test substance is calculated. Thus, in the proposed method of measuring changes in the parameters of spectra, operations to record spectral curves on a plotter, to visually analyze the nature of changes in the parameters of the spectrum, to measure the magnitude of changes in the parameters of the spectrum using a measuring instrument and to recalculate the resultant data are eliminated; EPR spectral lines or through appropriate scale factors. In addition, the proposed method allows the automation of the measurement process through the use of a program of a different command device controlled from the recording system and the memory block. The command device starts the measurement process itself and gives a command to the memory unit to store and transfer the measured values to the processing unit. If the data processing device is associated with an influence quantity control system b, then the proposed method of measuring automatic EPR or NMR analyzers can be applied to control technological processes. The functional relationship between the values of the measured durations of time intervals and the napaMeTpa w of the EPR spectral lines or (Fig. 2), as well as the measurement error of the present invention, could be shown in the following specific example. Let the EPR or NPR absorption line of the test substance be Gaussian, then the equation of the first derivative for the normed Gaussian absorption line has the form .Ne-pH -. where the maximum (amplitude) value of the first derivative of the absorber line is: 1, 1 - / I and H H - the current value of the magnetic field strength; HQ is the resonance value of the magnetic field strength; line width absorbed. As a result of any effect or change in the magnitude of the effect, the test substance does not change in the intensity of the absorption signal with the remaining spectrum parameters unchanged, which is often the case in the practice of kinetic EPR or NMR studies. The resulting signal of the first derivative of the absorption line can be written as,. where the maximum amplitude value of the first derivative of the decompression line after the changing effect on the test substance, I - Io a - // 2LI

X 01, l 0.5

1 0,01648 0.08233 D-, 00375 0.12368 From the above results of calculations it can be seen that the greater the value of V, the greater the error of the approximation GH- (day X - 0.2, it reaches g.- 65

0.2

0.15

0.1

Claims (2)

0.16404 0.24454 0.32321 0.49750 1.11746 1.97890 Let 3 ". J, N times, or N. we find N in accordance with the proposed invention. At the time of passage of the signals 3, and j through the value of the reference voltage, their values 3 (DIZ-) p. equal between oh and exactly correspond to the value of the coupon voltage, i.e. -iK- 4v- iK-) X exp then 2g (":-), D 01 i de represents the desired value Hod, g j, g I: 1 a 1 iJ The measurement error of the proposed method. appreciate this error. We decompose to the exponent in a power series of the form - e rz. (4l - x l5. (.-X) - 1. The maximum possible error when decomposing in a row is obtained when X0. We accept this assumption, then we write 1-1 "- - 5 h., Ixn g ZGG. Since this series is convergent, for a rough estimate it suffices to restrict the first two members of the series, i.e. (-) h-ix - i Thus, the maximum possible measurement error in the present invention is determined by the duration of the time interval for the smallest signal value of the first derivative (i.e. -P). To numerically estimate the magnitude of X (i.e., the maximum possible measurement error), we approximate curve 3 with a straight line at the point where the sign of the first derivative changes. Let us find the error 1, the received approximation l for different values of x. The results of the calculations are given below (the values are normalized to (Do 1) ti 2%) and, therefore, the magnitude of the measurement error is also greater. From here we can formulate the requirements for c. & ODU magnitude reference voltage. which must be less than the amplitude value of the voltage of the first derivative of the smallest of the compared signals and which determines the value of X. We find the value of the maximum measurement error in the present invention when the value of the reference voltage is in the range (0.1 - 0.032): :) ; . For a reference voltage equal to 0.32 P, 0.2) we get (), 1Л, 1со, 2) o, 98 Since in the ideal case (measurement inaccuracy) exPf-xCx - 1, then the relative maximum The measurement error is equal to.) Thus, the maximum possible measurement error of the proposed method (with a reference voltage equal to 0.32 of the amplitude value of the first derivative of the smaller of the compared signals) does not exceed 2% and the smaller the smaller reference voltage. A similar approach can be applied in such cases when, as a result of exposure or change in the magnitude of the effect on the test substance, either only a change in the width of the absorption line or a change in the width and intensity of the spectral line occurs simultaneously with the remaining spectral parameters. The change in the shape of the spectral line should be taken into account according to the method described in 1 and 2. The proposed measurement method can be used not only to determine the magnitude of the change in the parameters of the EPR or NMR spectra, but also to determine the nature and magnitude of the effect on the substance when the correlation between the parameters of the spectrum of the substance and the changes in the physical and chemical properties of the substance occurring is known. as a result of exposure or change in exposure magnitude. The use of the proposed method of measuring changes in the EPR or NMR spectrum parameters has the following advantages in comparison with the known methods: measuring the magnitude of changes in the parameters of the PZR or NMR spectra directly in the process of recording spectra, which reduces the time for obtaining information about changes in a substance and thereby increases the efficiency of scientific research using the method of EPR or NMR; automation of the measurement process is possible; It is possible to use the proposed method of measurement in automatic EPR or NMR analyzers designed to control technological processes. The invention The method of measuring changes in the parameters of the EPR or NMR spectra. sequential measurement of the changing parameters of these spectra before and after the changing effect on the test substance and comparison, characterized in that, in order to reduce the measurement time of the parameters of the EPR spectra of the gamma and NMR and to enable the automation of the measurement process, before and after the changing impact on the substance measure the time intervals between two moments of coincidence of the magnitude of the reference voltage with the magnitude of the voltage of these signals before and after passing through the zero value of the first Noah. Sources of information taken into account in the examination 1.Pul Ch. Technique of EPR - spectroscopy. M., Mir, 1970, p. 9 - 29. 2. Wertz D., Bolton D. Theory and practical applications of the EPR method. World, 1975, p. 44 - 47, 501 - 505 (prototype) -. / Uir