Abstract
The infrared spectrum of propynal, C 2 HCHO, is studied at high resolution (0.003 cm -1 ) in the range 570-640 cm -1 . The relatively intense ν 11 (C{triple bond, long}C-H out-of-plane bend, 693 cm -1 ) and ν 7 (C{triple bond, long}C-H in-plane bend, 651 cm -1 ) fundamental bands are linked by a strong a-type Coriolis interaction. The somewhat weaker ν 8 (CCO in-plane bend, 614 cm -1 ) fundamental has a significant Fermi-type interaction with the "dark" background state 3ν 9 (∼618 cm -1 ). About 1400 lines are assigned and analyzed in terms of a four-state fit in order to obtain accurate band origins, rotational and centrifugal distortion parameters, and Fermi and Coriolis interaction parameters. This represents the first systematic high-resolution infrared study of propynal. Crown Copyright © 2008.