The v7, v8, and v11 bands of propynal, C2HCHO, in the 650 cm-1 region

The infrared spectrum of propynal, C2HCHC, is studied at high resolution (0.003 cm(-1)) in the range 570640 cm(-1). The relatively intense v(11) (C equivalent to C-H out-of-plane bend, 693 cm(-1)) and v(7) (C equivalent to C-H in-plane bend, 651 cm(-1)) fundamental bands are linked by a strong a-type Coriolis interaction. The somewhat weaker v(8) (CCO in-plane bend, 614 cm(-1)) fundamental has a significant Fermi-type interaction with the dark background state 3v(9) (similar to 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 (C) 2008 Published by Elsevier Inc. All rights reserved.