Rotational Infinite Order Sudden Approximation

Atabek, O., Beswick, J.A., and Delgado-Barrio, G. (1985). A test of the rotational infinite order sudden approximation in molecular fragmentation, J. Chem. Phys. 83, 2954-58. 

Using a Rotational Infinite Order Sudden Approximation [RIOSA) to describe the exiting contmua. X- -BC[v, j ) yielded in the vibrational predissociation of X BC complexes, we outline a fitting procedure of the van der Waals interaction to get agreement with the available experimental data. Assuming an additive pairwise model of Lennard-Jones or Morse atom-atom functional forms, reasonable parameters are obtained under a low computational cost for the He ICl[B) and Ar Cl2[B) systems. 

Goldflam R., Green S., Kouri D. J. Infinite order sudden approximation for rotational energy transfer in gaseous mixtures, J. Chem. Phys. 67, 4149-61, (1977). 

Key words Centrifugal sudden approximation - Infinite order sudden approximation - Sudden approximations -Inelastic collisions - Rotationally inelastic collisions... 

A simple well-known extension of a collinear Landau-Teller model is provided by the breathing sphere (BSP) model of Schwartz, Slawsky and Herzfeld [13] which fully retains the Landau-Teller exponential factor. More consistent treatment, which approximately takes into account the anisotropic character of the atom-molecule interaction, is based on the so-called infinite order sudden approximation (lOSA) [14] with respect to rotational transitions that accompany the vibrational transition. Within this approximation the rotation of the relaxing molecule plays the role of a spectator, which insignificantly modifies the exponent in Eq. (8) through quite unimportant redefinition of a. If, in addition, the quasiclassical correction to the semiclassical Landau-Teller exponent is small and the effect of the attractive part of the potential is weak, one can write the following simple expression for the deactivation rate constant within BSP or lOSA approximation ... 

The above treatment of linearly driven vibrations has been thoroughly tested by calculations of Li ions scattering from N, [62], for which there is available a wealth of experimental data [87, 120] as well as independent theoretical studies. For instance, Secrest et al. did a fully-quantal study using the infinite-order sudden approximation to simplify the rotational problem [135] Billing classically treated the relative and rotational motions while describing vibrations quantum mechanically by means of eigenfunction expansions with time-dependent coefficients [HI] in addition, purely classical simulations have also been performed for Li -N, [121, 122], We first summarize the comparison between our TCF and Billing s semiclassical results, and then illustrate a TCF analysis of experimental measurements. 

R. Schinke and P. McGuire, Rotational rainbow oscillations in He-Na2 collisions Comparison between coupled states and infinite order sudden approximations, J. Chem. Phys. 71 4201... 

Maxwellian distribution 129 infinite-order sudden (IOS) approximation 155-6 semi-classical calculation 136-7 Sack s model rotational relaxation 19 strong collision model 219 scattering see isotropic scattering spectra ... 

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