MILLIMETER-WAVE AND HIGH-RESOLUTION INFRARED-SPECTRA OF MONOISOTOPIC (SCSE)-SE-80 - EQUILIBRIUM, GROUND-STATE, AND V(1), MV(2), AND NV(3) ROVIBRATIONAL PARAMETERS

The Fourier transform infrared spectrum of monoisotopic (SCSe)-Se-80 h as been investigated in the nu(2), nu(3), 2 nu(2) 2 nu(3), and nu(1) r egions with a resolution between 3 and 4 X 10(-3) cm(-1). In addition, the millimeter-wave spectrum has been studied in the region 150 to 32 0 GHz, and ground and nu(2) = 1 excited state transitions have been me asured. Ground state constants, B-0 = 2043.285 4(4) MHz and D-0 = 146. 5 3(5) Hz, have been determined from a merge of millimeter-wave data a nd ground state combination differences spanning J values up to 77 and 143, respectively. The band centers nu(2) = 352.341 075(9) cm(-1) and nu(3) = 505.480 06(5)cm(-1) have been determined. The rovibrational p arameters of numerous overtone and combination levels (nu(1) nu(2)(l2) nu(3)) = 02(0)0, 02(2)0, 03(1)0, 03(3)0, 04(0)0, 04(2)0, 00(0)2, and 00(0)3 have been obtained from polynomial analyses whose standard devi ations ranged from 0.7 to 3.5 X 10(-4) cm-(1). The 10(0)0 level, nu(ef f) 1435.840 cm(-1), is anharmonically perturbed by the 04(0)0 level, w ith an avoided crossing at J = 55, and W-1222 = 0.963 09(1) cm(-1). Tr ansitions to both the upper (E(+)) and lower (E(-)) sublevels of the d yad were observed for 1 less than or equal to J' less than or equal to 117 and 4 less than or equal to J' less than or equal to 171, respect ively, and the deperturbed wavenumbers nu(1) = 1435.542 76(2) and 4 nu (2)(0) = 1432.725 00(3) cm(-1) were derived. Furthermore, a local cros sing of the E(-) and 04(2)0 levels involving l-type resonance was obse rved at J = 91. (C) 1995 Academic Press, Inc.