Diode laser spectroscopy of the ν8 band of the SF5Cl molecule

Diode laser spectra of SF(5)Cl have been recorded in the nu(8) band region at a temperature of ca. 240 K, a pressure of 0.25 mbar and an instrumental bandwidth of ca. 0.001 cm(-1). Four regions have been studied: a first one in the P-branch (906.849-907.687 cm(-1)), a second one in the Q-branch (910.407-910.944 cm(-1)), and two other ones in the R-branch (913.957-914.556 and 917.853-918.705 cm(-1) ). The whole nu(1)/nu(8) dyad of SF(5)35Cl has been previously recorded in the group of Professor H. Burger in Wuppertal, thanks to a Fourier transform infrared spectrometer. These data have thus been combined with our diode laser ones in the aim of refining the analysis. We used an effective Hamiltonian developed up to the fourth order and a set of programs called C(4nu)TDS. One thousand three hundred and forty-six transitions for nu(1), 495 (FTIR: 351; diode laser: 144) transitions for nu(8), and 406 ground state combination differences have been assigned and fitted. A global fit has been obtained with a rms of 0.00081 cm(-1) for the nu(1) band, 0.0012 cm(-1) for the FTIR data of the nu(8) band, 0.00055 cm(-1) for the diode laser data of this same band, and 0.00064 cm(-1) for the ground state. It appears that more data (for instance, using a supersonic jet) are still necessary to obtain a completely satisfactory analysis of the nu(8) region.