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Energy-dependent energy transfer: deactivation of azulene (S/sub 0/, E/sub vib/) by 17 collider gases

Journal Article · · J. Chem. Phys.; (United States)
OSTI ID:6301212

Collisional deactivation of highly vibrationally excited azulene in the electronic ground state was investigated using infrared fluorescence detection. Azulene (S/sub 0/, E) was prepared with Eapprox. =17 500 cm/sup -1/ and Eapprox. =30 600 cm/sup -1/ by laser excitation at 600 and 337 nm, respectively. Advantage was taken of the fast internal conversion rate to S/sub 0/ azulene from S/sub 1/(600 nm) and S/sub 2/(337 nm) electronic states. The collider gases investigated are He, Ne, Ar, Kr, Xe, H/sub 2/, D/sub 2/, N/sub 2/, CO, O/sub 2/, CO/sub 2/, H/sub 2/O, NH/sub 3/, CH/sub 4/, SF/sub 6/, n-C/sub 4/H/sub 10/, and unexcited azulene. The results are expressed in terms of <..delta..E(E)>, the average energy transferred per collision, which can depend on the vibrational excitation energy E of the azulene. Using previously obtained knowledge of the dependence of infrared fluorescence intensity on E (M. J. Rossi and J. R. Barker, Chem. Phys. Lett. 85, 21 (1982)), two methods were used to obtain <..delta..E(E)> values from the fluorescence decay curves: (1) an approximate method that considered only the average energy, and (2) solution of the full collisional master equation. Both methods gave <..delta..E(E)> values that depend strongly on E. The limited experimental information on the identity of the energy-transfer processes operative in the deactivation of azulene is discussed. Additional experimental results on vibration-to-vibration energy transfer from azulene to CO/sub 2/ are presented, which indicate that the emission at 4.3 ..mu..m observed previously (J. R. Barker, M. J. Rossi, and J. R. Pladziewicz, Chem. Phys. Lett. 90, 99 (1982)) originates not only from CO/sub 2/(001), but from other states with one quantum of excitation in ..nu../sub 3/. The experimental results are discussed in terms of models for energy transfer, which have appeared in the literature. It is concluded that only a superficial understanding exists and theory has lagged far behind experiments on energy transfer.

Research Organization:
Department of Chemical Kinetics, SRI International, Menlo Park, California 94025
OSTI ID:
6301212
Journal Information:
J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 78:11; ISSN JCPSA
Country of Publication:
United States
Language:
English