Polarization dephasing

In the first reported measurements made with picosecond pulses, an optical beam splitter was used to pick off a portion of the pulse train and a variable optical delay path was introduced between the two beams [7]. The main beam was used to excite (pump) a dye sample, and the weak (probe) beam was used to monitor the recovery of dye transmission as a function of delay. Over the past two decades, this pump-probe method has been extended to a variety of measurement geometries and used to measure electronic polarization dephasing times as well as population lifetimes. 

Figure Bl.3.7. A WMEL diagram for the seventh order Raman echo. The first two field actions create the usual Raman vibrational coherence which dephases and, to the extent that inliomogeneity is present, also weakens as the coherence from different cliromophores walks oflP. Then such dephasing is stopped when a second pair of field actions converts this coherence into a population of the excited vibrational state / This is followed by yet another pair of field actions which reconvert the population into a vibrational coherence, but now one with phase opposite to the first. Now, with time, the walked-oflP component of the original coherence can reassemble into a polarization peak that produces the Raman echo at frequency oi = 2(o - (O2...

Figure Bl.3.8. A WMEL diagram for die three-colour fifth order qiiasi-Ramaii echo . As usual, the first pair of field actions creates the Raman coherence which is allowed both to dephase and walk off with time. This is followed by a second pair of field actions, which creates a different but oppositely phased Raman coherence (now hf) to the first. Its frequency is at oi - oij = Provided that frequencies are identified with an inliomogeneous distribution that is similar to those of the frequencies, then a quasi-rephasing is possible. The fifth field action converts the newly rephased Raman polarization into the quasi-echo at co = 2(b, — CO, = CO, + CO,...

Accurate experimental determinations require that not only the handedness of the produced light, but its exact degree of polarization, are known. The theoretical performance of an undulator may be in practice be degraded by magnetic defects, and the optical beam can be further depolarized by reflections along the beamline. Again, the dephasing on optical elements can in principle be... 

Iwata K, Ozawa R, Hamaguchi H (2002) Analysis of the solvent- and temperature-dependent Raman spectral changes of S1 trans-stilbene and the mechanism of the trans to cis isomerization dynamic polarization model of vibrational dephasing and the C=C double-bond rotation. J Phys Chem A 106 3614—3620... 

DQ coherence between C (,-) and C m and then let the DQ coherence evolve under the influence of the heteronuclear I3C-15N dipole-dipole interaction [181, 182]. The virtue of this design is that it can be easily combined with other resolution enhancement technique such as INADEQUATE [183]. Alternatively, the magnetization of C (,) dephased under the 13C-15N dipolar coupling can be transferred to C (j) for another period of 13C-15N dipolar dephasing [183]. This idea can be combined with the NCOCA experiment so that the superior resolution provided by the C (,-)-N(j+i) correlation could be exploited. The overall efficiency, however, is relatively low due to the use of two polarization-transfer steps, viz. 15N —> 13C and 13C —> 13C [183]. In comparison with the techniques, the advan-... 

The rotational dynamics of nitrogen and carbon dioxide were recorded by Akhmanov and Koroteev [7]. The transients look similar to the transients by Morgen et al. [8], recorded with time resolved Raman induced polarization spectroscopy [9]. A fs-DFWM experiment was performed by Frey et al. [10] on diatomics and linear polyatomics. To prevent collisional dephasing, they transferred the method into the expansion zone of a molecular beam. In succession, experiments on linear molecules and symmetric tops were performed on molecules like CHCI3 [11] and CgHf, [12], Transients of asymmetric tops like the near oblate pyrimidine, pyrazine and pyridine [13] and SO2 [11] were reported in the following years. 

Coherent dissociation Geminate recombination Dephasing Proton transfer Electron transfer Vibrational relaxation 8arrierless reactions Bimolecular reactions Ionic reactions Solvation dynamics Friction dynamics Polarization (kerr)... 

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