Rotationally Resolved Near-Infrared Spectrum of the HCCI Ã1A″ ← X̃1A′ Transition

Bor Chen Chang, Trevor J. Sears

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Near-infrared spectra of the HCCl Ã1A″(0,1,0) ← X̃1A′(0,0,0) and Ã1A″(0,0,1) ← X̃1A′(0,0,0) transitions between 13 100 and 13 330 cm-1 were obtained at Doppler-limited resolution using a combination of frequency-modulation (FM) and transient absorption techniques. For the Ã(0,1,0) ← X̃(0,0,0) vibronic band, we have rotationally resolved and assigned five subbands (Ka = 0 ← 1, 1 ← 0, 1 ← 2, 2 ← 1, and 2 ← 3) of HC35Cl and the Ka = 0 ← 1 subband of HC37Cl. The rotational structure of the Ã(0,1,0) level shows strong perturbations. Both random perturbations and anomalous K-type doublings were observed. A detailed analysis qualitatively reveals the roles of the Renner-Teller effect and spin-orbit interaction in perturbation mechanisms. In addition, the Ã(0,0,1) ← X̃(0,0,0) transition was observed for the first time. The determined C-Cl stretching frequency in the à state indicates an increase of 20% on electronic excitation and is consistent with the determined C-Cl bond shortening.

Original languageEnglish
Pages (from-to)391-403
Number of pages13
JournalJournal of molecular spectroscopy
Issue number2
StatePublished - Oct 1995


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