Vibrationally mediated photodissociation of ethene isotopic variants preexcited to the fourth C-H stretch overtone

Evgeny Bespechansky, Alexander Portnov, Amir Zwielly, Salman Rosenwaks, Ilana Bar

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9 Scopus citations

Abstract

H and D photofragments produced via vibrationally mediated photodissociation of jet-cooled normal ethene (C2 H4), 1,2-trans- d2 -ethene (HDCCDH), and 1,1- d2 -ethene (C H2 C D2), initially excited to the fourth C-H stretch overtone region, were studied for the first time. H and D vibrational action spectra and Doppler profiles were measured. The action spectra include partially resolved features due to rotational cooling, while the monitored room temperature photoacoustic spectra exhibit only a very broad feature in each species. Simulation of the spectral contours allowed determination of the band types and origins, limited precision rotational constants, and linewidths, providing time scales for energy redistribution. The H and D Doppler profiles correspond to low average translational energies and show slight preferential C-H over C-D bond cleavage in the deuterated variants. The propensities toward H photofragments emerge even though the energy flow out of the initially prepared C-H stretch is on a picosecond time scale and the photodissociation occurs following internal conversion, indicating a more effective release of the light H atoms.

Original languageEnglish
Article number133301
JournalJournal of Chemical Physics
Volume125
Issue number13
DOIs
StatePublished - 12 Oct 2006

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