Study of Energy Transfer in Methane by Excitation of Fundamental, Overtone, and Combination Bands
The relaxation of combination and overtone excitations in methane is shown to proceed rapidly via nearly resonant vibration- to- vibration (V → V) transfers. An angle-tuned optical parametric oscillator with 3 to 10 mJ/pulse was employed  to excite different vibrational levels of CH4 in the 1.66 – 3.55 μ region. To probe level populations fluorescence intensity vs time was observed for the infrared active υ3 and υ4 modes. A filter cell containing CH4 absorbed fundamental, v3, 4 = 1 → 0, fluorescence and passed hot-band fluorescence. Thus upper levels could be distinguished from the fundamentals.
KeywordsVibrational Level Combination Band Filter Cell Millisecond Timescale Versus Transfer
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- P. Hess and C. B. Moore, to be published.Google Scholar