The laser induced fluorescence spectrum of the HeCl2 van der Waals molecule

Laser-induced fluorescence excitation spectra of free-jet expansions of He and Cl2 have been recorded. Spectroscopic features observed ∼3.5 cm−1 to the blue of the free 35Cl2 vibronic origins of the 7–0 through the 12–0 bands of the B 3Π0+u–X 1Σ+g system were attributed to the He35Cl2 molecule. The observed spectra were well simulated by a T-shaped, rigid, asymmetric top model. The spectra were observed to display homogeneous broadening dependent on the vibrational band excited. Predissociation lifetimes were calculated and structural parameters determined by fitting the observed contours. The distance from the He atom to the Cl2 center of mass is 3.8±0.4 and 3.9±0.4 Å for the ground and excited states, respectively.