The nu(2) bands of the deuterated species D2Se and HDSe

For the first time D2Se and HDSe as Se-80 monoisotopic and natural material were studied in the region of the nu(2) fundamental vibration by high-reso lution (0.0033 cm(-1)) Fourier transform infrared spectroscopy. For (DSe)-S e-2 which is an asymmetric rotor with C-2v symmetry the nu(2) band is of B type while for HDSe (C-s symmetry) it is a hybrid band, and both A- and B-t ype transitions were observed. Depending on the isotopic abundances, 300-10 00 lines were assigned for each of the isotopic Se-M species (M = 76, 77, 7 8, 80, and 82). The corresponding (010) experimental rotational levels, obt ained by adding the observed line positions to the ground state levels deri ved from J.-M. Flaud, Ph. Areas, O. N. Ulenikov. G. A. Onopenko, N. E. Tyab aeva, W. Jerzembeck, and H. Burger, (J. Mel. Spectrosc., in press) were fit ted satisfactorily using a Watson-type Hamiltonian in A reduction and I-r-r epresentation: the rms deviations are ranging from 1.5 to 4.3 x 10(-4) cm(- 1) depending on the isotopic species. Hamiltonian constants up to high orde r (octic terms) were determined for each isotopic species. For the most abu ndant Se isotopic species, namely Se-80, the band centers are nu(0) ((D2Se) -Se-80) = 741.67503 cm(-1) and nu(0) ((HDSe)-Se-80) = 900.43820 cm(-1). (C) 1999 Academic Press.