Unimolecular dissociation of cyclopentadiene and indene

Journal Article · Wed May 01 00:00:00 EDT 1991 · Journal of Chemical Physics; (USA)

DOI:https://doi.org/10.1063/1.460433· OSTI ID:5732840

Yi, W; Chattopadhyay, A; Bersohn, R ^[1]

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1. Department of Chemistry, Columbia University, New York, New York 10027 (US)

The dissociation of hydrogen atoms from the methylene group of cyclopentadiene (CP) and indene (ID) excited with a 193 nm photon has been studied by hydrogen atom laser induced fluorescence. The rate of dissociation of IND was 7.4{times}10{sup 6} s{sup {minus}1} but that of CP was too fast to measure. The ratio of H atoms to D atoms generated from 5-deuteriocyclopentadiene (5-dCP) was 3.91{plus minus}0.46. Rice--Ramsberger--Kassel--Marcus theory was used to calculate the rates of dissociation of CP and 5-dCP. The quantum yield for dissociating H atoms from CP was 0.85{plus minus}0.07. The ejected H atoms have a Maxwell velocity distribution with temperatures which are equal to the vibrational temperatures, 3690 and 2479 K for CP and IND, respectively. The most important result of the work is this confirmation of an earlier finding on a different set of molecules that the translational temperature of the fragments {ital after} the dissociation is equal to the vibrational temperature {ital before} the dissociation. This is explained by the assumption that the motion of the fast, light hydrogen atom is partly decoupled from that of the heavier, slower atoms.

• OSTI ID: 5732840
• Journal Information: Journal of Chemical Physics; (USA), Vol. 94:9; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
CYCLOPENTADIENE
PHOTOLYSIS
INDENE
CHEMICAL REACTION KINETICS
DISSOCIATION
FAR ULTRAVIOLET RADIATION
FLUORESCENCE SPECTROSCOPY
HYDROGEN
ALKENES
AROMATICS
CHEMICAL REACTIONS
CONDENSED AROMATICS
CYCLOALKENES
DECOMPOSITION
DIENES
ELECTROMAGNETIC RADIATION
ELEMENTS
EMISSION SPECTROSCOPY
HYDROCARBONS
KINETICS
NONMETALS
ORGANIC COMPOUNDS
PHOTOCHEMICAL REACTIONS
POLYENES
RADIATIONS
REACTION KINETICS
SPECTROSCOPY
ULTRAVIOLET RADIATION
400500* - Photochemistry