The high-resolution infrared spectrum of the ν5 band of deuterated formic acid (DCOOH)

The Fourier transform infrared spectrum of the v, band of deuterated formic acid (DCOOH) has been measured with a resolution of 0.004 cm(-1) in the frequency range of 1090-1180 cm(-1). Using a Watson's A-reduced Hamiltonian in the I' representation, a total of 1731 assigned unperturbed transitions have been analyzed to provide rovibrational constants for the upper state (upsilon(5) = 1) with a standard deviation of 0.000363 cm(-1).The band is A type with an unperturbed band center at 1142.31075 +/- 0.00002 cm(-1). The band is expected to be perturbed by a nearby upsilon(4) band through a Fermi resonance term and possibly a Coriolis term. The resonance is particularly noticeable for K-d = 10, and 11, at high J values. About 215 perturbed lines were identified but they were not included in the final fit. (C) 1998 Academic Press.