High Resolution Study of the nu2 , 2nu1 , nu1 + nu3 , and 2nu3 Bands of Hydrogen Telluride: Determination of Equilibrium Rotational Constants and Structure.

High resolution Fourier transform spectra of a natural and a 130 Te monoisotopic sample of H2 Te have been recorded at a resolution of 0.0022 cm-1 in the 11.6 μm spectral region, as well as a spectrum of a natural sample of H2 Te at a resolution of 0.0051 cm-1 in the 2.4 μm region. In the 11.6 μm region the main absorbing band is the nu2 band, the analysis of which was rather easy. On the other hand, in the 2.4 μm region three bands are absorbing, namely 2nu1 , nu1 + nu3 , and 2nu3 , the last being much weaker than the others. The analysis in this spectral domain was much more difficult because of resonances. Indeed it proved not possible to reproduce the observed lines without taking into account the Darling-Dennison interaction between the levels of the (200) and (002) states and the Coriolis interactions between the levels of (200) and (101) and between those of (101) and (002). Considering these interactions allowed us to calculate very satisfactorily all the experimental levels, and precise sets of vibrational energies and rotational and coupling constants were obtained for the seven most abundant H2 Te isotopic species, namely H2 130 Te, H2 128 Te, H2 126 Te, H2 125 Te, H2 124 Te, H2 123 Te, and H2 122 Te. For the most abundant species, H2 130 Te, the band centers in cm-1 are nu0 (nu2 ) = 860.6563, nu0 (2nu1 ) = 4062.8842, nu0 (nu1 + nu3 ) = 4063.3697, and nu0 (2nu3 ) = 4137.0454. These results, combined with those obtained for other vibrational states, have been used to derive the equilibrium rotational constants and their corrections. Finally, by neglecting the electronic corrections, the equilibrium structure of H2 130 Te was obtained as follows: r e (Te-H) = 1.65145(10) A, alphae (HTeH) = 90.2635(90)degrees.