Observation of collision-induced-dipole absorption bands in strontium-rare-gas mixtures. II. Bands involving high-lying states

We have observed many collision-induced-dipole (CID) absorption bands arising from the transitions between quasimolecular ground and high-lying (n ≤ 10) states in the strontium-rare-gas systems. For each absorption band, we have measured the energy shift of the absorption peak from the energy of the correlating atomic forbidden transition and the effective oscillator strength per unit perturber density f_CID/N_p. The shift is roughly proportional to the electron scattering length L₀ for each rare-gas atom, whereas the f _CID/N_p is roughly proportional to L₀². The shift decreases in general as the principal quantum number n increases, and increases as one goes from the s state to the d state, and to the degenerate manifold state with l≥3. These general features of the shift and f_CID/N_p are consistent with the predictions by a simple Fermi-potential model, suggesting the important role of the interaction between a Rydberg electron and a rare-gas atom in the CID absorption processes.