Near-Infrared Spectroscopy of Bromomethylene in a Slit-Jet Expansion

✍ Scribed by Bor-Chen Chang; Matthew L. Costen; Andrew J. Marr; Grant Ritchie; Gregory E. Hall; Trevor J. Sears

• Publisher: Elsevier Science
• Year: 2000
• Tongue: English
• Weight: 253 KB
• Volume: 202
• Category: Article
• ISSN: 0022-2852
• DOI: 10.1006/jmsp.2000.8116

✦ Synopsis

Several rotational subbands of the bromomethylene (HCBr) and deuterated bromomethylene (DCBr) A ˜1AЉ 4 X ˜1AЈ origin band in the region of 830 -840 nm have been recorded under slit-jet cooled conditions that result in rotational and translational temperatures of approximately 20 K. The radical was formed by 193-nm laser photolysis of bromoform in the early stages of the expansion and detected by absorption of a single-frequency Ti:sapphire ring laser. The spectral simplification achieved compared to earlier measurements at ambient temperature allowed a nearly complete rotational analysis. The data were combined with additional measurements at room temperature in order to determine rotational constants and estimate a structure for the radical in its ground state. With the exception of KЈ ϭ 0, the excited state levels were found to suffer multiple perturbations due to interactions with the manifold of excited X ˜state levels caused by Renner-Teller and anharmonic coupling. Atomic bromine transitions from the 4 P 5/ 2 level at 63 400 cm Ϫ1 were also observed in the source following absorption of at least two 193-nm photons by the precursor.