Direct laser-induced emission detection of the S1 and T1 states of germanium dichloride: Pyrolysis jet spectroscopy and ab initio studies.

Spectra of jet-cooled germanium dichloride were obtained by pyrolysis of trichlorogermane in the throat of a supersonic jet. Laser-induced emission excitation spectra were recorded for the weak 450–400 nm and strong 320–300 nm band systems, both of which were vibrationally analyzed. Ab initio predictions of the excited state geometries, vibrational frequencies, and excitation energies were made to aid in assigning the spectra. The strong ultraviolet band system is assigned as A 1B1–X 1A1 with upper state vibrational frequencies of ν1=354 cm-1 and ν2=104 cm-1. It is the direct analog of the 580–440 nm band system of dichlorocarbene. The weaker band system in the visible is shown to be the a 3B1–X 1A1 transition, with upper state vibrational frequencies of ν1=393 cm-1 and ν2=118 cm-1. This is the first report of direct laser-induced phosphorescence detection of the excited triplet state of any of the carbene or heavier carbene analogs. [ABSTRACT FROM AUTHOR]