Solvent-dependent vibrational relaxation pathways after successive resonant IR excitation to υ = 2
✍ Scribed by Mischa Bonn; Marco J.P. Brugmans; Huib J. Bakker
- Publisher
- Elsevier Science
- Year
- 1996
- Tongue
- English
- Weight
- 445 KB
- Volume
- 249
- Category
- Article
- ISSN
- 0009-2614
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✦ Synopsis
With two subsequent resonant intense picosecond infrared pulses, we have succeeded in pumping a significant fraction of iodoform molecules in solution to the second vibrationally excited state of the C-H stretching mode. Transient populations of the vibrational levels are monitored with weak probe pulses. From these pump-pump-probe experiments, we find that the subsequent relaxation route depends critically on the solvent. In a strongly polar solvent (acetone) relaxation from ~: = 2 to tJ = 0 occurs predominantly via the v = 1 state, with time constants of 7"12-1 = 10+5 and 7"11~° = 60+5 ps, respectively. In contrast, in a less polar solvent (chloroform) direct decay to the ground state is observed, with a time constant (T~ 2~° = 80+20 ps), comparable to the energy lifetime of the first excited state (T~ l~° = 125±5 ps).