Dispersed fluorescence spectroscopy of the GeCl₂ Ã-X̃ transition

The laser-induced fluorescence excitation spectrum of the Ge Cl2 Ã - X̃ transition at ultraviolet wavelengths (300-320 nm) was recorded in a direct current discharge supersonic free jet expansion. The excitation spectrum contains several sharp peaks and a congested diffuse structure. Dispersed fluorescence spectra following the excitation of these Ge Cl2 ultraviolet bands were successfully acquired for the first time. The analysis of the dispersed fluorescence spectra reveals the detailed vibrational structure of the X̃ A11 state. We have assigned the vibrational structures corresponding to different isotopomers (Ge35 Cl2, Ge35 Cl37 Cl, and Ge37 Cl2). The vibrational fundamental frequencies were determined: 409 cm-1 (symmetric stretch), 159 cm-1 (bend), and 352 cm-1 (antisymmetric stretch) for the X̃ A11 state of Ge Cl2. Vibrational parameters of the ground electronic state including vibrational frequencies, anharmonicity, and bend-stretch coupling constant were determined. Our dispersed fluorescence spectra also clarify the vibrational assignments of the hot bands and provide more experimental data for unraveling the nature of the congested diffuse structure at shorter wavelengths in the excitation spectrum.