Isotope substitution in near local-mode H2X molecules: Stretching fundamental bands of HDSe

The high-resolution FTIR spectrum of the HDSe molecule in the presence of H 2Se and D2Se was recorded on Se-80 monoisotopic and natural samples in the 1500-2900 cm(-1) region and theoretically analyzed in the regions of the st retching fundamental bands v(1) and v(3) near 1692 and 2351 cm(-1), respect ively. The analysis was performed starting from derived isotopic relations between vibration-rotation, anharmonic, centrifugal distortion, and other p arameters which reveal high predictive power. Strong resonance interactions between the states (100) and (020) are taken into account, and sets of par ameters which reproduce the experimental rotation-vibration energies of the (100) and (001) states with a mean accuracy of 0.00008 and 0.00009 cm(-1), respectively, for the (HDSe)-Se-80 species, were obtained. For the less ab undant species, for which some higher order terms were constrained, slightl y worse agreement was achieved. The refined spectroscopic parameters are ve ry close to their predicted values, (C) 1999 Academic Press.