HIGH-RESOLUTION STUDY OF THE V(5)=1 LEVEL OF CDF3

The degenerate fundamental vibrational level v(5) = 1 has been studied using FTIR and sub-Doppler CO2 laser-sideband spectroscopy, providing the most accurate vibration-rotation transition wavenumbers to this l evel measured so far, with resolved A(1)-A(2) splittings of the kl = 1 and kl = -2 levels. Combined with rotational frequencies measured in the v(5) = 1 level by millimeter-and submillimeter-wave spectroscopy, we performed a simultaneous fit reproducing all data with minor excep tions quantitatively. Unlike the recent study of the v(6) = 1 level of CDF3 [H. Burger et al., J. Mol. Spectrose 182, 34-49 (1997).] the uni tary equivalence of reduced Hamiltonians for an isolated degenerate fu ndamental level of a C-3v molecule was not confirmed for the level stu died, making one of the reduced Hamiltonians more suitable for the rep resentation of experimental data. (C) 1997 Academic Press.