Search

The ground state vibrational energy levels of jet-cooled H[sub 2]CSi and D[sub 2]CSi have been studied by a combination of wavelength-resolved fluorescence and stimulated emission pumping (SEP) techniques. By taking advantage of the vibrational selection rules and Franck-Condon factors and selectively pumping upper state single vibronic levels, readily assignable low-resolution emission spectra were obtained. Higher resolution SEP spectra were recorded to give precise measurements of the vibrational band origins of many of the lower-lying vibrational levels. All of the vibrational frequencies, except for the Franck-Condon inactive CH asymmetric stretching mode, ν[sub 5], have been determined for both isotopomers. The CH[sub 2] rocking mode (ν[sub 6]) is found to have a very low 263 cm-1 frequency in the ground state. The spectra are complicated by unexpected activity in the out-of-plane bending vibration. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

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. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]