The {ital T}{sub 1}({ital n}{pi}{asterisk}){l_arrow}{ital S}{sub 0} laser induced phosphorescence excitation spectrum of acetaldehyde in a supersonic free jet: Torsion and wagging potentials in the lowest triplet state

Journal Article · Thu Aug 01 04:00:00 EDT 1996 · Journal of Chemical Physics

DOI:https://doi.org/10.1063/1.472120· OSTI ID:434671

Liu, H; Lim, E C ^[1]; Munoz-Caro, C; Nino, A ^[2]; Judge, R H ^[3]; Moule, D C ^[4]

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1. Knight Chemical Laboratory, The University of Akron, Akron, Ohio 44325-3601 (United States)
2. E. U. Informatica, Universidad de Castilla---La Mancha, Ronda de Calatrava 5, 13071 Ciudad Real (Spain)
3. Department of Chemistry, University of Wisconsin---Parkside, Kenosha, Wisconsin 53141-2000 (United States)
4. Department of Chemistry, Brock University, St. Catharine`s, Ontario L2S 3A1 (Canada)

The laser induced {ital T}{sub 1}({ital n}{pi}{asterisk}){l_arrow}{ital S}{sub 0} phosphorescence excitation spectrum of jet-cooled acetaldehyde has been observed for the first time with a rotating slit nozzle excitation system. The vibronic origins were fitted to a set of levels that were obtained from a Hamiltonian that employed flexible torsion-wagging large amplitude coordinates. The potential surface extracted from the fitting procedure yielded barriers to torsion and inversion of 609.68 and 869.02 cm{sup {minus}1}, respectively. Minima in the potential hypersurface at {theta}=61.7{degree} and {alpha}=42.2{degree} defined the equilibrium positions for the torsion and wagging coordinates. A comparison to the corresponding {ital S}{sub 1}-state parameters showed that the torsion barrier (in cm{sup {minus}1}) does not greatly change, {ital S}{sub 1}/{ital T}{sub 1}=710.8/609.7, whereas the barrier height for the wagging-inversion barrier increases dramatically, 574.4/869.0. {copyright} {ital 1996 American Institute of Physics.}

• OSTI ID: 434671
• Journal Information: Journal of Chemical Physics, Journal Name: Journal of Chemical Physics Journal Issue: 7 Vol. 105; ISSN JCPSA6; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
ACETALDEHYDE
CONFORMATIONAL CHANGES
ELECTRONIC STRUCTURE
FLUORESCENCE SPECTROSCOPY
LASER RADIATION
METHYL RADICALS
POTENTIAL ENERGY SURFACES
TORSION
TRIPLETS
VIBRONIC STATES