Differential scattering study of asymptotically forbidden optical transitions in CaAr collisions

We have investigated the laser excitation of CaAr collision pairs in a molecular beam experiment with differential detection. The metastable Ca(4s3d)1D state is populated by a collision-assisted transition. Measurements of differential cross-sections are reported showing interference structures. The spectral dependence of the signal intensity is characterized by the presence of a satellite structure in the Σ–Σ transition and the asymptotically vanishing dipole function. The experimental data are in good agreement with ab initio theoretical results.