Inelastic scattering rotational

Parker G A and Pack R T 1978 Rotationally and vibrationally inelastic scattering in the rotational lOS approximation. Ultra-simple calculation of total (differential, integral and transport) cross sections for nonspherical molecules J. Chem. Phys. 68 1585... 

It is generally accepted that the centrifugal sudden (CS) approximation is the most reliable approximate method. Its results are usually very close to those obtained by ab initio close coupling (CC) calculations. The integral and differential cross-sections of Ar inelastic scattering on nitrogen were performed for a few low-frequency rotational transitions and four different interaction potentials [205]. Much better agreement of CC with CS results was found than with IOS calculations performed in... 

Connor J. N. L., Sun H., Hutson J. M. Exact and approximate calculations for the effect of potential anisotropy on integral and differential cross-sections Ar-N2 rotationally inelastic scattering, J. 

Under some circumstances the rotationally anisotropy may be even further simplified for T-R energy transfer of polar molecules like HF (41). To explore this quantitatively we performed additional rigid-rotator calculations in which we retained only the spherically symmetric and dipole-dipole terms of the AD potential, which yields M = 3 (see Figures 1, 3, and 4). These calculations converge more rapidly with increasing N and usually yield even less rotationally inelastic scattering. For example Table 2 compares the converged inelastic transition probabilities... 

Thermal distributions of NO(u 2, J, A Ej,) states were observed, wherein the population in any level was determined by the internal energy and the parameter Tr. and independent of spin-orbit state or lambda doublet species. This is in contrast to the rotational rainbows, the propensities for preferential population in the Il(A ) lambda doublet species and the Fj spin orbit state which were observed in direct inelastic scattering of NO/Ag(l 11). 

Fig. 5. Rotational temperatures ofNO desorbing from Pt(l 11). The data are representative of data published for (x) neat thermal desorption , ( +) thermal desorption in the presence of coadsorbed C0 ° (solid squares) and (solid triangles) trapping/desorption in molecular beam scattering, (open triangle) reaction limited desorption from NO-NHj complexes, (open circle) and (open square) NHj oxidation reactions. The solid line is for full accommodation. The dashed curve represents results for translational energy measurements in direct inelastic scattering ...

Figure 3.19. Variation of the energy transfer into the surface in scattering of NO from Ag(l 11) as a function of Ee = f ccsO,-. Solid lines and solid points are for rotationally elastic scattering. /, = Jj = 0.5 and the open points are for non-state-resolved scattering experiments (and therefore also contains a contribution from rotationally inelastic scattering). From Ref. [181].

The energy analysis of these inelastically scattered electrons is carried out by a cylindrical sector identical to the monochromator. The electrons are finally detected by a channeltron electron multiplier and the signal is amplified, counted and recorded outside of the vacuum chamber. A typical specularly reflected beam has an intensity of 10 to 10 electrons per second in the elastic channel and a full width at half maximum between 7 and 10 meV (60-80 cm l 1 meV = 8.065 cm-- -). Scattering into inelastic channels is between 10 and 1000 electrons per second. In our case the spectrometer is rotatable so that possible angular effects can also be studied. This becomes important for the study of vibrational excitation by short range "impact" scattering (8, 9, 10). 

The inelastic neutron TOF spectrum of a butane monolayer adsorbed on Carbopack B at 80 K (10) is shown at the top of Fig. 6. The background inelastic scattering from the substrate has been subtracted. Typical counting time for such a spectrum is -100 hours. The intramolecular torsional modes of the CH, and CH groups observed in the bulk liquid and solid (23) are also found in the monolayer spectrum. In the two methyl torsionsal modes the CH, groups rotate either in the same or opposite sense about the terminal C-C bonds, and in the CH2-CH torsion the two halves of the molecule rotate in the opposite sense about the internal C-C bond. In addition to the intramolecular torsional modes, new features appear in the monolayer spectrum which are not observed in bulk samples an intense peak at -112 cm"-1 and a broader band centered at 50 cm-1. 

Buck, U. (1982). Rotationally inelastic scattering of hydrogen molecules and the non-spherical interaction, Faraday Discuss. Chem. Soc. 73, 187-203. 

Korsch, H.J. and Schinke, R. (1980). A uniform semiclassical sudden approximation for rotationally inelastic scattering, J. Chem. Phys. 73, 1222-1232. 

Bergmann, K., Hefter, U. and Witt, J. (1980). State-to-state differential cross sections for rotationally inelastic scattering of Na2 by He, J. 

Jones, P.L., Hefter, U., Mattheus, A., Witt, J., Bergmann, K., Muller, W., Meyer, W and Schinke, R. (1982). Angular resolved rotationally inelastic scattering of Na2-Ne Comparision between experiment and theory, Phys. Rev. A, 26, 1283-1301. 

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