Theoretical studies of collisional relaxation of highly excited SO{sub 2} in an Ar bath

Conference · Sun Dec 31 04:00:00 EST 1995

OSTI ID:198725

Lendvay, G ^[1]; Schatz, G C ^[2]; Harding, L B ^[3]

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1. Hungarian Academy of Sciences, Budapest (Hungary). Central Research Inst. for Chemistry
2. Northwestern Univ., Chicago, IL (United States). Dept. of Chemistry
3. Argonne National Lab., IL (United States)

This paper describes molecular dynamics studies of collisional relaxation of highly excited SO{sub 2} in an Ar bath. Most of the calculations use a newly developed global ab initio potential surface for SO{sub 2} that correctly describes the superoxide (SOO) and ring isomers of SO{sub 2} that occur as secondary minima on the ground state potential surface at high energies (about 75% of the dissociation energy) above the C{sub 2v} minimum. Rate constants for the S + O{sub 2} and O + SO reactions are calculated to test this surface, and to examine the importance of electronically excited states in the O + SO recombination. The Ar + SO{sub 2} collisions are described by summing the ab initio potential with empirical intermolecular potentials. The resulting average vibrational energy transfer <{Delta}E> per collision is in good agreement with direct measurements (done at energies where the secondary minima are not populated) at 1000K, but the agreement is poorer at 300K. The agreement is significantly better than was obtained in a previous theoretical study, and our results indicate that the use of improved intramolecular and intermolecular potentials is crucial to obtaining the better results. The energy dependence of <{Delta}E> is found to be much stronger at energies where the secondary minima on the potential surface are accessible, however much of this effect is reproduced using a potential that has the same dissociation energy but not the secondary minima.

• Research Organization: Argonne National Lab., IL (United States)
• Sponsoring Organization: USDOE, Washington, DC (United States)
• DOE Contract Number: W-31109-ENG-38
• OSTI ID: 198725
• Report Number(s): ANL/CHM/CP--87834; CONF-951229--2; ON: DE96007263
• Country of Publication: United States
• Language: English

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