T/sub 1/ barrier height, S/sub 1/--T/sub 1/ intersystem crossing rate, and S/sub 0/ radical dissociation threshold for H/sub 2/CO, D/sub 2/CO, and HDCO

Journal Article · Thu Oct 01 04:00:00 EDT 1987 · J. Chem. Phys.; (United States)

OSTI ID:6286062

Chuang, M; Foltz, M F; Moore, C B

Vacuum UV laser-induced fluorescence has been used to detect the atomic products in the photofragmentation of H/sub 2/CO, D/sub 2/CO, and HDCO. The dissociation is shown to occur on both the ground (S/sub 0/) and the first triplet (T/sub 1/) potential surfaces. The T/sub 1/ exit barrier height (2.9--6.0 kcal/mol) and the S/sub 1/..-->..T/sub 1/ intersystem crossing rate near the T/sub 1/ barrier top (4 x 10/sup 7/ s/sup -1/) have been determined experimentally. The threshold energy for the radical dissociation channel on the S/sub 0/ surface, 86.57 +- 0.16 kcal/mol, has also been measured accurately by rovibronically resolved photolysis. The best values for the heat of formation (9.99 +- 0.19 kcal/mol) and the C--H bond enthalpy (15.69 +- 0.19 kcal/mol) of HCO radical have been derived from the measured threshold energies as well.

• Research Organization: Department of Chemistry, University of California Berkeley, California 94720; Materials and Chemical Sciences Division, Lawrence Berkeley Laboratory Berkeley, California 94720
• DOE Contract Number: AC03-76SF00098
• OSTI ID: 6286062
• Journal Information: J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 87:7; ISSN JCPSA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400500* -- Photochemistry
ACYL RADICALS
ALDEHYDES
CHEMICAL BONDS
CHEMICAL REACTIONS
DECOMPOSITION
DEUTERIUM COMPOUNDS
DISSOCIATION
ENERGY
ENTHALPY
FORMALDEHYDE
FORMATION HEAT
FORMYL RADICALS
HYDROGEN COMPOUNDS
ORGANIC COMPOUNDS
PHOTOCHEMICAL REACTIONS
PHOTOLYSIS
PHYSICAL PROPERTIES
POTENTIAL ENERGY
RADICALS
REACTION HEAT
THERMODYNAMIC PROPERTIES