The laser induced fluorescence spectrum of SiF around 193 nm

Fluorescence of SiF radicals induced by a tunable ArF excimer laser is reported. The radicals are prepared using laser vaporization and subsequent supersonic cooling. A tentative assignment of the most prominent features in the spectrum is given. The spectrum deviates from what can be expected from the extensive emission spectroscopic data. Delayed fluorescence detection is used to unravel the congested structure, and a previously unobserved electronic state, which we label D(2)²Π, with (in cm^-1) T_ve = 52128.7 ± 0.1, B_v = 0.629 ± 0.001, A_v = 5.7 ± 0.1, and (in nsec) τ = 110 ± 8, is characterized. Franck-Condon factor calculations permit the vibrational assignment of the excited state on the basis of the dispersed fluorescence spectrum.