Competition between photochemistry and energy transfer in ultraviolet-excited diazabenzenes. II. Identifying the dominant energy donor for ''supercollisions''
- Department of Chemistry and Columbia Radiation Laboratory, Columbia University, New York, New York 10027 (United States)
CO{sub 2} bath molecules scattered into J=72 of the 00{sup 0}0 vibrational state at short times after 248 or 266 nm UV excitation of pyrazine are probed using high resolution time resolved IR diode laser spectroscopy as a function of UV laser fluence from {approx}3 to 80 mJ/cm2. The implications of pyrazine photodissociation for the interpretation of these collisional energy transfer experiments are considered. Specifically, the possibility that translationally hot HCN resulting from pyrazine dissociation may be the source of excitation for collisions that impart a large amount of rotational and translational energy to CO{sub 2} molecules is examined. Transient absorption measurements probing rotationally and translationally excited CO{sub 2} molecules produced following excitation of pyrazine are analyzed within the context of a kinetic scheme incorporating pyrazine photodissociation, as well as excitation of CO{sub 2} by both translationally hot HCN and vibrationally excited pyrazine. This analysis indicates that vibrationally hot pyrazine, which has sufficient energy to dissociate, is the source of excitation in collisions imparting large amounts of rotational and translational energy to CO{sub 2}. (c) 2000 American Institute of Physics.
- OSTI ID:
- 20215716
- Journal Information:
- Journal of Chemical Physics, Vol. 112, Issue 13; Other Information: PBD: 1 Apr 2000; ISSN 0021-9606
- Country of Publication:
- United States
- Language:
- English
Similar Records
Molecular supercollisions: Evidence for large energy transfer in the collisional relaxation of highly vibrationally excited pyrazine by CO{sub 2}
Long- and short-range interactions in the temperature dependent collisional excitation of the antisymmetric stretching CO{sub 2}(00{sup 0}1) level by highly vibrationally excited pyrazine