Toshio IBUKI (IMS and Kyoto Univ. Educ.), Mitsuhiko KONO (IMS and Univ. Tokyo), Yukiko ASARI (Kyoto Univ. Educ.), Atsunari HIRAYA (IMS and Hiroshima Univ.) and Kosuke SHOBATAKE (Nagoya Univ.)
[J. Chem. Phys. 106, 4853 (1997)]
Absolute photoabsorption and fluorescence cross sections of gaseous SiCl4 have been measured in the energy region 6.2-31 eV by using synchrotron radiation as a light source. Higher order light from a 1-m Seya monochromator has been suppressed by use of an Ar gas filter in the range of 11.3-15.5 eV (110-80 nm) and a LiF window at h(nu) < 11.8 eV (105 nm). Emissions have been observed for the C2T2 -> Ã2T2 and C2T2 -> X2T2 processes of SiCl4+ molecular ion and the Ã1B1 -> X1A1 and 3B1 -> X1A1 of SiCl2 radical. Total fluorescence cross section has been determined to be 22.4 ± 1.0 Mb at 21.22 eV. By comparing with the partial formation cross section of the C2T2 ionic state [Carlson et al., J. Chem. Phys. 84, 641 (1986)], it has been concluded that the SiCl4+(C2T2) formed decays through radiative processes with quantum yield (PHI)f ~ 1. The experimental results provide information on the breakdown pathways of the SiCl4+(C2T2) state ion. The bands observed in photoabsorption and fluorescence excitation spectra have been assigned as the (4s, np, and np') <- 3t2, (4s and np) <- 1e, (4s and 4p) <- 2t2, and (np and nd) <- 2a1 Rydberg series. The ionization energies for (2t2)-1 and (2a1)-1 have been found to be 15.04±0.03 and 18.17±0.03 eV, respectively.