Excitation spectra of CdNe and CdAr van der Waals molecules were produced in a molecular beam employing free-jet supersonic expansion, crossed with a pulsed dye-laser beam. Bands arising from A ${}_{}{}^3{}_{}{}^{}$$0^{+}$←X ${}_{}{}^1{}_{}{}^{}$$0^{+}$ and B ${}_{}{}^3{}_{}{}^{}$1←X ${}_{}{}^1{}_{}{}^{}$$0^{+}$ transitions between vibrational levels were analyzed, yielding spectroscopic constants for the three states. Computer simulations of the bands combined with the application of the London dispersion relation led to values for $r_e$, the equilibrium internuclear separations. The effective lifetimes of the CdAr${(}^3$$0^{+}$) and CdAr${(}^3$1) molecules in various vibrational states were also determined and were found to be affected by quenching collisions.

• Received 31 August 1989

DOI:https://doi.org/10.1103/PhysRevA.41.243