Scattering dynamics observables

Around the defect, enhanced scattering was observed and this loss of extinction is the origin of the name. The exact nature of the images can only be explained using dynamical diffraction theory and we will return to this in a later section. 

Dynamic smdies of the alloy system in CO and H2 demonstrate that the morphology and chemical surfaces differ in the different gases and they influence chemisorption properties. Subnanometre layers of Pd observed in CO and in the synthesis gas have been confirmed by EDX analyses. The surfaces are primarily Pd-rich (100) surfaces generated during the syngas reaction and may be active structures in the methanol synthesis. Diffuse scattering is observed in perfect B2 catalyst particles. This is attributed to directional lattice vibrations, with the diffuse streaks resulting primarily from the intersections of 111 reciprocal lattice (rel) walls and (110) rel rods with the Ewald sphere. 

In this section, we give the reader the necessary theoretical and computational ingredients used to compute scattering and predissociation dynamics observables with an emphasis on how to include the GP and non-adiabatic couplings. 

Figure 7 summarizes the data for two key dynamic observables the mean-square monomer displacement gi,mid(0 and i,end(0 and the stress relaxation fimction. Hgures 7(a) and 7(b) show the data as a limction of time in units where f= l,feBT= 1 and unit length is b in Rouse and semiflexible models, Tq in freely jointed and freely rotating models, and a in the LJ+FENE-based models. Since these units are pretty arbitrary and the local details are very different (including presence of inertia), the results are scattered and it is not easy to see similarities and differences between the models. 

A strong motivation for the great experimental effort to measure such detailed quantities like j-dependent cross sections is that they certainly also contain detailed information on the microscopic motion of the particles which is useful to improve our insight into the dynamics of elementary chemical reactions. There are two well established ways to extract clues about the microscopic events from cross sections. The one requires the knowledge of a PES and the computational simulation of data. The desired information is then deduced from the degree of agreement achieved and from the analysis of the scattering dynamics. The other way is to conceive a transparent model of the microscopic motion which directly relates the characteristic properties of the interaction with the observed features. In the subsequent Section 4.1 we touch on the first way whilst in Section 4.2 we concentrate on the second. 

In all these time-resolved experiments the principles of pump-probe laser spectroscopy are the key element in the experimental design. A laser pulse is optically split into two components of unequal amplitude. The intense fraction, acting as a pump piilse, is directed towards the target or sample cell to trigger the molecular event under study. The much attenuated probe pulse monitors the absorption, raman scattering, polarization, coherence, or phase shift, which is linked explicitly to the dynamical observable under investigation. Extremely precise time... 

As we showed, cf. (2.23) and (2.20), the dynamic observable in an OKE experiment, and also in the forward depolarized light scattering (see also Sect. 2.4.2) is the correlation of the susceptibility or dielectric fluctuations ... 

The scattering techniques, dynamic light scattering or photon correlation spectroscopy involve measurement of the fluctuations in light intensity due to density fluctuations in the sample, in this case from the capillary wave motion. The light scattered from thermal capillary waves contains two observables. The Doppler-shifted peak propagates at a rate such that its frequency follows Eq. IV-28 and... 

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