The ultrafast photochemical ring-opening reaction of 1,3-cyclohexadiene in cyclohexane

Autor:	Neil A. Anderson, Stuart H. Pullen, Larry A. Walker, Roseanne J. Sension
Rok vydání:	1998
Předmět:	education.field_of_study Absorption spectroscopy Cyclohexane Chemistry Population General Physics and Astronomy Quantum yield Photochemistry Reaction rate chemistry.chemical_compound Excited state Ultrafast laser spectroscopy Physical and Theoretical Chemistry Ground state education
Zdroj:	The Journal of Chemical Physics. 108:556-563
ISSN:	1089-7690 0021-9606
DOI:	10.1063/1.476366
Popis:	The ring-opening reaction of 1,3-cyclohexadiene in cyclohexane solution and the subsequent photoproduct cooling dynamics have been investigated by using two-color transient absorption kinetic measurements and novel time-resolved absorption spectroscopy in the 260–300 nm spectral region. The initial photoproduct in this reaction, s-cis,Z,s-cis-1,3,5-hexatriene (cZc-HT) is formed on a ∼250 fs time scale. Spectra deduced for time delays very close to zero, as well as calculated Rice–Ramsperger–Kassel–Marcus unimolecular reaction rates, provide strong evidence that the quantum yield for the reaction is determined before any relaxation occurs on the ground state. Upon formation, the vibrationally excited hexatriene photoproduct is able to isomerize around C–C single bonds freely. As a result, the evolution observed in the transient absorption measurements represents a combination of rotamer population dynamics and thermalization due to energy transfer to the solvent. Three distinct time scales for relaxation a...
Databáze:	OpenAIRE
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