Multiple relaxation times

From this table, it is seen that the eigenvalues of B, or, equivalently, the inverse relaxation times are in our description integer multiples of the unknown kj. The point we want to stress is that these integers are different for each process P so that, even if the five rate constants k,-... 

Although the idea of generating 2D correlation spectra was introduced several decades ago in the field of NMR [1008], extension to other areas of spectroscopy has been slow. This is essentially on account of the time-scale. Characteristic times associated with typical molecular vibrations probed by IR are of the order of picoseconds, which is many orders of magnitude shorter than the relaxation times in NMR. Consequently, the standard approach used successfully in 2D NMR, i.e. multiple-pulse excitations of a system, followed by detection and subsequent double Fourier transformation of a series of free-induction decay signals [1009], is not readily applicable to conventional IR experiments. A very different experimental approach is therefore required. The approach for generation of 2D IR spectra defined by two independent wavenumbers is based on the detection of various relaxation processes, which are much slower than vibrational relaxations but are closely associated with molecular-scale phenomena. These slower relaxation processes can be studied with a conventional... 

Suppose the multiple Maxwell model which describes the material we are interested in is composed of m processes each with an elasticity Gj, a viscous process with a viscosity rjj and a corresponding relaxation time ty. We can form the relaxation function by adding all these models together ... 

In the limit of zero gradient, the sequence reduces to the Hahn echo, and it is conventional to expand the echo amplitude as a multiple exponential function of T, and define, the usual transverse relaxation times, T,... 

The reaction is coupled to an indicator color change which is much faster than the metal substitution step. L refers to the multidentate ligands which were employed to avoid multiple relaxations r is the relaxation time. 

The C spectra of both compounds include all carbon multiplicities, i.e. CH CH, CH and C and are ideal to demonstrate methods for spectra editing. Furthermore they include carbon nuclei with rather different T, relaxation times. 

Th4Hi5. Three kinds of information are obtained from the samples of Th4H15 information on rigid lattice structure from free induction decays, on proton motion from relaxation time measurements, and on internal fields from peak locations that were found using the multiple pulse techniques. Figure 1... 

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