Rotationally resolved hot atom collisional excitation of CO/sub 2/ 00/sup 0/1 and 00/sup 0/2 stretching vibrations by time-resolved diode laser spectroscopy
A tunable infrared diode laser has been used to monitor the time-resolved absorption of rovibrationally excited CO/sub 2/ molecules produced in collisions with fast hydrogen atoms from the 193 nm excimer laser photolysis of H/sub 2/S. Nascent relative rotational population distributions were measured for the 00/sup 0/1 and 00/sup 0/2 vibrational states in CO/sub 2/ following collisional excitation. The nascent distributions for both of these states were found to be significantly displaced from the 300 K Boltzmann distribution with peaks at J = 31 and J = 34 for 00/sup 0/1 and 00/sup 0/2, respectively. An approximate diffusion treatment for the mass transport of fast moving hydrogen atoms out of the region of the diode laser probe beam was developed and used to obtain approximate absolute scattering cross sections. Sufficient energy is available in the H/CO/sub 2/ collision process to excite 00/sup 0/1 rotational states with J greater than 140. The fall-off in excitation probability for J>31 is ascribed to the small impact parameter necessary to produce vibrationally excited CO/sub 2/ (00/sup 0/1). This in turn limits the total angular momentum available in those collisions which actually produce 00/sup 0/1. These results are compared with previous experiments measuring the total probability for collisional excitation of all ..nu../sub 3/ quanta as well as with various models for inelastic collisional scattering.
- Research Organization:
- Department of Chemistry and Columbia Radiation Laboratory, Columbia University, New York, New York 10027
- OSTI ID:
- 5375942
- Journal Information:
- J. Chem. Phys.; (United States), Vol. 88:10
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
CARBON DIOXIDE
ATOM-MOLECULE COLLISIONS
EXCITATION
HYDROGEN
HYDROGEN SULFIDES
INFRARED SPECTRA
LASER SPECTROSCOPY
PHOTOLYSIS
ROTATIONAL STATES
VIBRATIONAL STATES
ATOM COLLISIONS
CARBON COMPOUNDS
CARBON OXIDES
CHALCOGENIDES
CHEMICAL REACTIONS
COLLISIONS
DECOMPOSITION
ELEMENTS
ENERGY LEVELS
ENERGY-LEVEL TRANSITIONS
EXCITED STATES
HYDROGEN COMPOUNDS
MOLECULE COLLISIONS
NONMETALS
OXIDES
OXYGEN COMPOUNDS
PHOTOCHEMICAL REACTIONS
SPECTRA
SPECTROSCOPY
SULFIDES
SULFUR COMPOUNDS
640304* - Atomic
Molecular & Chemical Physics- Collision Phenomena