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Proceedings Paper

New laser system for measurements of dissociation rates of small molecules with picosecond temporal resolution
Author(s): Ralph Tadday; Jason C. Crane; P. P. Radkowski; R. Shu; C. Bradley Moore
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Paper Abstract

A technique is presented for studying state-specific picosecond unimolecular reaction dynamics of small molecules in their ground electronic states, and hence their thermal unimolecular reactions. Formyl fluoride (HFCO) is chosen for its unique properties. HFCO dissociates over a barrier of 17,200 +/- 1,400 cm-1 to form HF + CO. It has been shown that intramolecular vibrational energy redistribution (IVR) is far from complete at such energies. Thus substantial state- and mode-selectivity are exhibited in vibrational couplings and dissociation rates. Stimulated emission pumping (SEP) is used to selectivity populate single rovibrational levels in the electronic ground state. A third, variably delayed laser pulse, probes the depleting population of molecules from this level by laser induced fluorescence. The high temporal resolution of the dump and the probe laser pulses is realized by two distributed- feedback dye lasers amplified in (beta) -barium borate crystals serving as optical parametric amplifiers. The complete system is pumped by one active passive mode-locked Nd:YAG laser. The system delivers two independently tunable 16 ps laser pulses with a bandwidth of 1.48 cm-1 and energies of up to 1 mJ.

Paper Details

Date Published: 15 May 1998
PDF: 10 pages
Proc. SPIE 3271, Laser Techniques for State-Selected and State-to-State Chemistry IV, (15 May 1998); doi: 10.1117/12.308389
Show Author Affiliations
Ralph Tadday, Univ. of California/Berkeley (United States)
Jason C. Crane, Univ. of California/Berkeley (United States)
P. P. Radkowski, Univ. of California/Berkeley (United States)
R. Shu, Univ. of California/Berkeley (United States)
C. Bradley Moore, Univ. of California/Berkeley (United States)

Published in SPIE Proceedings Vol. 3271:
Laser Techniques for State-Selected and State-to-State Chemistry IV
John W. Hepburn; Robert E. Continetti; Mark A. Johnson, Editor(s)

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