Direct identification of photofragment structures formed in the 193 nm photodissociation of thiophene
- Ames Lab., IA (United States)
An experimental scheme which involves vacuum ultraviolet photoionization mass spectrometric sampling of laser photodissociation products in a pulsed supersonic molecular beam has been used to identify the isomeric structures of the 193 nm photofragments from thiophene. The primary products observed are vinylacetylene (H[sub 2]C=CH-C=CH), acetylene (C[sub 2]H[sub 2]), and thioketene (H[sub 2]C=C=S). Using the 2 + 1 resonance-enhanced multiphoton (REMPI) scheme, we find that S atoms are produced predominantly ([ge]96%) in [sup 3]P[sub J] states with a fine structure distribution of [sup 3]P[sub 2]:[sup 3]P[sub 1]:[sup 3]P[sub 0] = 0.82 [+-] 0.03:0.15 [+-] 0.03:0.03 [+-] 0.03. These experimental results indicate that the major dissociation channels are CH[sub 2]=CH-C=CH + S([sup 3]P) and CH=CH + CH[sub 2]=C=S. Ab initio multiconfiguration self-consistent-field calculations have been made to rationalize these experimental observations. 52 refs., 4 figs., 3 tabs.
- DOE Contract Number:
- W-7405-ENG-82
- OSTI ID:
- 6766697
- Journal Information:
- Journal of Physical Chemistry; (United States), Journal Name: Journal of Physical Chemistry; (United States) Vol. 99:6; ISSN JPCHAX; ISSN 0022-3654
- Country of Publication:
- United States
- Language:
- English
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400102* -- Chemical & Spectral Procedures
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400500 -- Photochemistry
664200 -- Spectra of Atoms & Molecules & their Interactions with Photons-- (1992-)
74 ATOMIC AND MOLECULAR PHYSICS
ACETYLENE
ALKYNES
BRANCHING RATIO
COMPILED DATA
CROSS SECTIONS
DATA
ELECTRON SPECTROSCOPY
ENERGY LEVELS
ENERGY SPECTRA
EXCITED STATES
HETEROCYCLIC COMPOUNDS
HYDROCARBONS
INFORMATION
IONIZATION
MASS SPECTROMETERS
MEASURING INSTRUMENTS
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC SULFUR COMPOUNDS
PHOTOELECTRON SPECTROSCOPY
PHOTOIONIZATION
SELF-CONSISTENT FIELD
SPECTRA
SPECTROMETERS
SPECTROSCOPY
THIOPHENE