Classical line shapes based on analytical solutions of bimolecular trajectories in collision induced emission. II. Reactive collisions
Abstract
The classical theory of collision induced emission (CIE) from pairs of dissimilar rare gas atoms was developed in Paper I [D. Reguera and G. Birnbaum, J. Chem. Phys. 125, 184304 (2006)], 10.1063/1.2371097 from a knowledge of the straight line collision trajectory and the assumption that the magnitude of the dipole could be represented by an exponential function of the internuclear distance. This theory is extended here to deal with other functional forms of the induced dipole as revealed by ab initio calculations. Accurate analytical expression for the CIE can be obtained by least square fitting of the ab initio values of the dipole as a function of interatomic separation using a sum of exponentials and then proceeding as in Paper I. However, we also show how the multiexponential fit can be replaced by a simpler fit using only two analytic functions. Our analysis is applied to the polar molecules HF and HBr. Unlike the rare gas atoms considered previously, these atomic pairs form stable bound diatomic molecules. We show that, interestingly, the spectra of these reactive molecules are characterized by the presence of multiple peaks. We also discuss the CIE arising from half collisions in excited electronic states, which in principle could be probed in photodissociation experiments.
 Publication:

Journal of Chemical Physics
 Pub Date:
 June 2013
 DOI:
 10.1063/1.4808107
 Bibcode:
 2013JChPh.138v4109R
 Keywords:

 ab initio calculations;
 excited states;
 hydrogen compounds;
 least squares approximations;
 moleculephoton collisions;
 photodissociation;
 spectral line breadth;
 33.70.Jg;
 33.80.Gj;
 31.15.A;
 Line and band widths shapes and shifts;
 Diffuse spectra;
 predissociation photodissociation;
 Ab initio calculations