Laser Stark and Fourier transform spectroscopy and assignment of optically pumped far-infrared laser lines of metbanol-D4

In this work, the Fourier transform far infrared (FTFIR) and infrared (IR) spectra of the completely deuterated methanol species CD3OD corresponding to the torsion-rotation band in the vibrational ground state and the C-O stretch vibrational band, respectively, have been recorded and analyzed. From the IR analysis it has been possible to partially identify optically pumped FIR laser lines for four different CO2 laser pump systems from analytical considerations. In addition, laser Stark spectra have been studied using the HCN laser lines operating at 311 and 337 mu m, in CD3OD. A number of Q-branch lines for K = 11<-- 10 E-2 n = 0 assigned earlier and two strong R-branch transitions viz. R(8) and R(10) for K = 7 <-- 6 A n = 0 have been considered. The laser Stark spectrum for the R(10) transition has been reassigned from the previous work. The availability of the zero field frequencies with a precision of +/- 6 MHz from the high resolution FTFIR spectrum allowed the dipole moment of this important molecular species to be determined for the first time. The results will be useful for accurate intensity calculation and prediction of optically pumped FIR laser lines and astrophysically significant transitions. (C) 1998 Elsevier Science B.V. All rights reserved.