Scattering molecular

Buck U 1974 Inversion of molecular scattering data Rev. Mod. Phys. 46 369 Buck U 1975 Elastic scattering Adv. Chem. Phys. 30 313... 

The foundations of the modem tireory of elementary gas-phase reactions lie in the time-dependent molecular quantum dynamics and molecular scattering theory, which provides the link between time-dependent quantum dynamics and chemical kinetics (see also chapter A3.11). A brief outline of the steps hr the development is as follows [27],... 

Actually equation (A3.4.72) for o. is still fomial, as practically observable cross sections, even at the highest quantum state resolution usually available in molecular scattering, correspond to certain sums and averages of... 

Alexander M H and Manolopoulos D E 1987 A stable linear reference potential algorithm for solution of the quantum close-coupled equations in molecular scattering theory J. Chem. Phys. 86 2044-50... 

This book presents an extensive and detailed description of basic teclmiques for the generation and detection of atomic and molecular beams, as well as beam teclmiques for the study of molecular scattering processes. 

The presence of the multiple arrangements make molecular scattering very challenging theoretically. After much trial and error, several teclmiques have been developed. These teclmiques generally fall into two broad categories ... 

Rayleigh Scattering the scattering of light by particles much smaller than the wavelength of the light, e.g., molecular scattering in the natural atmosphere. 

Analysis of the dependence of absorption and reflection coefficients on the frequency shows that the emission spectra of thick layers of melts are similar to their molecular scattering and are actually quite close to their absorption spectra. This analysis enables the assessment of the emission spectra of similar compounds with no need for any additional calculations [294,344]. 

In order to generate a set of calculated structure factors Fc(Q) from a set of coordinates, it is necessary to introduce a model for the time variation of the electron density. The usual assumptions in macromolecular crystallography include harmonic isotropic motion of the atoms and in addition, the molecular scattering factor is expressed as a superposition of atomic scattering factors. With these assumptions the calculated structure factor (equation III.2) is given by.27... 

The scattering of electrons by an atom pair separated by a rigid distance, r, averaged over all possible orientations in space, gives rise to a molecular scattering intensity function which can be represented in the following way1 ... 

Quantum Chemistry of Crystal Surfaces (Koutecky) Quantum Effects in Elastic Molecular Scattering (Bernstein). ... 

The atom-centered models do not account explicitly for the two-center density terms in Eq. (3.7). This is less of a limitation than might be expected, because the density in the bonds projects quite efficiently in the atomic functions, provided they are sufficiently diffuse. While the two-center density can readily be included in the calculation of a molecular scattering factor based on a theoretical density, simultaneous least-squares adjustment of one- and two-center population parameters leads to large correlations (Jones et al. 1972). It is, in principle, possible to reduce such correlations by introducing quantum-mechanical constraints, such as the requirement that the electron density corresponds to an antisymmetrized wave function (Massa and Clinton 1972, Frishberg and Massa 1981, Massa et al. 1985). No practical method for this purpose has been developed at this time. 

As in the case of photodissociation, the quantum theory of reactive molecular scattering was initially entirely based on time-independent scattering theory [4-7,100-123]. There were several early attempts to apply time-dependent quantum theory to reactive scattering processes [124—131]. But the modern era of the field really began with the seminal work of Kosloff et al. [37] and the subsequent application of his grid-based methods to the reactive scattering problem by Neuhauser and Baer and coworkers [45,132]. There have been many developments in the field [93,133-138], and several reviews and a book have been written on the topic [10,139-141]. My aim in the next section will be to outline the basic methods of time-dependent quantum theory used in reactive scattering calculations. While the review will cover many aspects of the theory, it will not cover all the approaches currently in use (as of 2003). 

Me,N-GaH3 molecule, molecular scattering intensity pattern, 41 186-187 [Me NlPhlC-Li], 37 76-77 Mercaptans, reactions with hexafluoroacetone, 30 274... 

There are a number of estimates of the actinic flux at various wavelengths and solar zenith angles in the literature (e.g., see references in Madronich, 1987, 1993). Clearly, these all involve certain assumptions about the amounts and distribution of 03 and the concentration and nature (e.g., size distribution and composition) of particles which determine their light scattering and absorption properties. Historically, one of the most widely used data sets for actinic fluxes at the earth s surface is that of Peterson (1976), who recalculated these solar fluxes from 290 to 700 nm using a radiative transfer model developed by Dave (1972). Demerjian et al. (1980) then applied them to the photolysis of some important atmospheric species. In this model, molecular scattering, absorption due to 03, H20, 02, and C02, and scattering and absorption by particles are taken into account. 

Fabelinskii, I. L., 1968. Molecular Scattering of Light, Plenum, New York. 

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