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Effect of isotopic substitution on the collisional quenching of vibronically excited CO/sup +/

Journal Article · · J. Chem. Phys.; (United States)
OSTI ID:5614251
Rovibronic levels of the A /sup 2/Pi/sub i/ state for /sup 12/C/sup 16/O/sup +/ and /sup 13/C/sup 16/O/sup +/ have been selectively excited by a pulsed, tunable dye laser and their time resolved fluorescence obtained as a function of helium pressure. These ions are formed by reaction of neutral carbon monoxide with helium metastable atoms created in a dc discharge. Since /sup 13/CO/sup +/ has essentially the same potential energy curves as /sup 12/CO/sup +/, but differs primarily in its vibrational energy spacings, this experiment accentuates the role, in the collisional deactivation process, of the high lying ground state vibrational levels which are adjacent to the laser populated vibronic levels of the A /sup 2/Pi/sub i/ state. Quenching rates are determined for the v' = 0, 1, and 2 levels which have relatively insignificant isotope shifts of a few wave numbers for the two isotopes. The difference in rates for the two isotopic ions demonstrates the importance of the positions for the high lying v'' = 10 and 11 ground state levels which have large isotope shifts of hundreds of wave numbers. A discussion of the deactivation process is given in terms of perturbations, Franck--Condon factors, energy gaps, and other considerations.
Research Organization:
Aeronomy Division, Air Force Geophysics Laboratory, Hanscom Air Force Base, Massachusetts 01731
OSTI ID:
5614251
Journal Information:
J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 79:8; ISSN JCPSA
Country of Publication:
United States
Language:
English