Inversion-recovery experiment

I and the measured line intensities are fitted to an exponential expression. S (-e) =A + B exp(-i / T ). The inversion-recovery experiments are often perfonned for multiline spectra of low-natural abundance nuclei,... 

Figure Bl.13.3. The inversion-recovery experiment. (Reproduced by pennission of VCFI from Banci L, Bertini I and Luchinat C 1991 Nuclear and Electron Relaxation (Weinlieim VCFI).)...

Fig. 1.—Diagrammatic Representation of the Recovery of Magnetization along the z-Axis (Mj), from Its Initial Value (-M ) to +Mo, Following Its Inversion by a 180° Pulse. The exponential recovery curve shown in [A] depicts the return of magnetization that would be found in a typical inversion-recovery experiment. The curve in [B] would be obtained from a three-pulse sequence, and is a plot of which decreases from an initial value of...

The idea of exploration of relaxation correlation was first reported in 1981 by Peemoeller et al. [23] and later by English et al. [24] using an inversion-recovery experiment detected by a CPMG pulse train. This pulse sequence is shown in Figure 2.7.1. 

T, values can be easily determined using pulse sequences which form part of the standard computer software, the most common one being the so-called inversion-recovery experiment. 

This experiment uses two pulses, 180° and 90°, separated by a delay time x which is varied. For each delay a certain number of FIDs are accumulated the result is a series of spectra in which the individual signals have different intensities. Figure 9 shows the result of an inversion-recovery experiment carried out on 1. 

Fig. 9 Spectra of compound 1 obtained from an inversion-recovery experiment. Pulse sequence fixed delay - 180° pulse - variable delay x - 90° pulse - acquisition of FID...

MHz, solvent CDC13 (degassed) T ] determination of the carbon atoms by inversion recovery experiment selected 13C spectra... 

Figure 6 The inversion-recovery experiment. The dynamic range is twice the equilibrium magnetization.

In some cases, CP is not necessary to obtain a suitable solid state NMR spectrum. In these cases, the SPE/MAS sequence may be used and for quantitative analysis only the X-nucleus T time needs to be determined. The standard inversion-recovery experiment (Fig. 10C) can be used to measure this... 

Fig. 1. Top Scheme of an inversion recovery experiment 5rielding the longitudinal relaxation time (inversion is achieved by mean of the (re) radiofrequency (rf) pulse, schematized by a filled vertical rectangle). Free induction decays (fid represented by a damped sine function) resulting from the (x/2) read pulse are subjected to a Fourier transform and lead to a series of spectra corresponding to the different t values (evolution period). Spectra are generally displayed with a shift between two consecutive values of t. The analysis of the amplitude evaluation of each peak from — Mq to Mq provides an accurate evaluation of T. Bottom the example concerns carbon-13 Tl of irans-crotonaldehyde with the following values (from left to right) 20.5 s, 19.8 s, 23.3 s, and 19.3 s.

Figure 1.41 H HP NMR inversion-recovery experiments on dissolved and bound Hj in a d -toluene solution of [Cr(r -H2)(CO)3(PCy3)2], 119-...

A commonly used method of measuring longitudinal relaxation times in multiline spectra, almost as old as Fourier transform NMR, is the inversion recovery experiment [1] which can be schematized by the pulse sequence... 

The T, Inversion-Recovery experiment is not restricted to C nuclei, but may also be applied to other nuclei, e.g, protons. In this case, the pulse sequence for the observe channel is the same, but no broadband decoupling is used. 

Fig. 3.19 Stacked plot of a C T, Inversion-Recovery experiment with peracetylated...

Determine the T, values of the individual carbon nuclei by analysing the data from the C Inversion Recovery experiment using the interactive fit routine of ID WINNMR. For further information consult Modern Spectral Analysis, volume 3 of this series, and the Help tool of ID WIN-NMR. Add the T, values to the C NMR data table. Try to rationalise the T, values with respect to the evaluated structure and the molecular dynamics of the investigated molecule. 

Calculate the T, values for the carbonyl carbons of the oligosaccharide. Load the raw data of the pseudo 2D C T, inversion recovery experiment D NMRDATA OLIGOSAC 1D C OCT1 2D 001001.SER. Decompose the 2D data matrix into a series of 1D FIDs, process and plot them according to the recommendations given in previous chapters. Exploit the options for automatic and serial processing. Determine the T, values for the individual carbon nuclei using the interactive fit routine of ID WIN-NMR. Use the Help information if necessary. 

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