HIGH-RESOLUTION INFRARED STUDY OF THE NU(4)-BAND, NU(5)-BAND, AND NU(6)-BAND OF TRANS-DIDEUTERO-DI-IMIDE, DNND

The gas-phase IR spectra of the a,b-Coriolis interacting band system n u(4),nu(6) around 950 cm(-1) and the nu(5) band around 2300 cm(-1) of N2D2 have been recorded with a resolution of ca. 0.005 and 0.007 cm(-1 ), respectively. In the nu(5) and nu(6) bands both a- and b-type compo nents are observed. In nu(4) the c- and a parallel-type component whic h obtains its intensity from the strong a-Coriolis resonance with nu(6 ) are observed. In addition, Delta K-a = +/-2 band components which ar e due to strong b-Coriolis perturbation are observed in both nu(4) and nu(6). From a simultaneous ground state combination difference analys is of all three bands the following ground state constants are obtaine d: A(0) = 6.0245356(22) cm(-1), B-0 = 1.08957754(33) cm(-1), and C-0 = 0.915155624(33) cm(-1). The upper stale energies from the nu(4), nu(6 ) band system have been analyzed using a dyad model including first an d higher order a- and b-Coriolis interactions between these levels. In the analysis of the nu(5) band weak higher order c-type and vibration al type Delta K-d = +/-2 interactions with the unobserved combination band nu(3) + nu(6) are taken into account. Upper state spectroscopic c onstants for all three Levels and a number of interaction constants ha ve been determined from these analyses. (C) 1996 Academic Press, Inc.