H-2 SE-80 - HIGH-RESOLUTION STUDY OF THE 2-NU(1)-NU(1), 2-NU(1)+NU(3)AND NU(1)+2-NU(3) BANDS(NU(2), NU(1)+NU(2)+NU(3), 3)

Using high-resolution Fourier transform spectra of monoisotopic (H2Se) -Se-80 recorded in the 1.8- and 1.55-mu m regions, an extensive analys is of the 2 nu(1) + nu(2), nu(1) + nu(2) + nu(3), 3 nu(1), 2 nu(1) + n u(3), and nu(1), + 2 nu(3) bands of this molecule has been performed, leading to a precise set of rotational levels for its {(210), (111)} a nd {(300), (201), (102)} vibrational states. For the first set of stat es, it was necessary to introduce the undetected (012) state in the Ha miltonian model, and the observed levels of {(210), (111)} were least- squares fit using a Hamiltonian which takes explicitly into account bo th the Coriolis interactions between the levels of(210) and(111) and o f(111)and (012), and the Darling-Dennison interaction between the leve ls of(210) and (012). For the second set of states, namely, {(300), (2 01), (102)}, the same type of situation occurs and it was necessary as well to introduce in the model the (003) vibrational state. In this w ay, all the experimental levels of {(210), (111)}, and {(300), (201), (102)} were calculated almost to within their experimental uncertainti es and a precise set of vibrational energies and rotational and coupli ng constants was derived with the band centers nu(0) (2 nu(1) + nu(2)) = 5612.7107, nu(0)(nu(1) + nu(2) + nu(3)) = 5613.7546, nu(0) (3 nu(1) ) = 6953.4607, nu(0) (2 nu(1) + nu(3)) = 6798.2084, and nu(0) (nu(1) 2 nu(3))= 6798.0967 cm(-1). (C) 1994 Academic Press, Inc.