State-selective dissociation of acetylene isotopomers

R. P. Schmid, Y. Ganot, T. Arusi-Parpar, R. J. Li, I. Bar, S. Rosenwaks

Research output: Contribution to journalConference articlepeer-review

1 Scopus citations

Abstract

Rovibrational excitation combined with promotion of C2HD/C2H2 molecules to the excited electronic trans-bent states Ã1Au/B̃1Bu and photofragment ionization are used to generate action spectra and Doppler profiles. Rovibrational states of C2HD (in the 15637 - 15735 cm-1 region) and C2H2 (in the 15480 - 15723 cm-1 region) are photodissociated by ∼ 243.1 nm photons that also probe the H/D fragments. The yield of both H/D photofragments is greatly enhanced upon rovibrational excitation of both isotopomers. In the photolysis of C2HD (5v1) (five quanta of C-H stretch) several couples of rotational transitions, terminating at the same upper rotational state (J'), stand out from the rotational contour and the H/D branching ratio is rotationally state dependent. In C2H2 photolysis the transition intensities of the combination bands that involve high stretch and low bend excitation, (1410020) and (2031100), are close to that of the fourth overtone of the C-H stretch, (2030000). In addition, in C2H2 some couples of rotational transitions stand out from the rotational contour, and the R(13) line of the (2030000) state shows anomalous intensity. The mechanism for the photoproducts preference in C2HD and for intensity enhancement in C2H2 is discussed.

Original languageEnglish
Pages (from-to)28-35
Number of pages8
JournalProceedings of SPIE - The International Society for Optical Engineering
Volume3271
DOIs
StatePublished - 1 Dec 1998
EventLaser Techniques for State-Selected and State-to-State Chemistry IV - San Jose, CA, United States
Duration: 29 Jan 199831 Jan 1998

Keywords

  • Acetylene isotopomers
  • Mode- and bond-selectivity
  • Photoproduct identity
  • Rovibrational excitation

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