Orbital angular momentum (Renner-Teller) effects in the (2)Pi(i) ground state of silicon methylidyne (SiCH)

The ground state vibrational energy levels of jet-cooled SiCH and SiCD have been studied by a combination of laser-induced fluorescence and wavelength-resolved fluorescence techniques. The radicals were produced by a pulsed electric discharge at the exit of a supersonic expansion using tetramethylsilane or methyltrichlorosilane as the precursor. Emission spectra have been obtained by pumping both perpendicular and parallel (vibronically induced) bands, providing complementary information on the Si-C stretching and Si-C-H bending modes. Ground state energy levels up to 4000 cm(-1) have been assigned and fitted using a vibrational Hamiltonian that incorporates Renner-Teller, spin-orbit, vibrational anharmonicity, and Fermi resonance interactions. The validity of the derived parameters has been tested using the isotope relations. (C) 2001 American Institute of Physics.