Line-broadening studies of excited diatomic homoatomic and heteroatomic Rydberg molecules formed by potassium, rubidium, and cesium atoms

Recent absorption measurements of the self-broadening of Rb principal series lines [ C. H. Greene, E. L. Hamilton, H. Crowell, C. Vadla and K. Niemax Phys. Rev. Lett. 97 233002 (2006)] verified the existence of minima in highly excited long-range potentials of Rb₂ which were predicted theoretically as bound Rydberg molecule [ C. H. Greene, A. S. Dickinson and H. R. Sadeghpour Phys. Rev. Lett. 85 2458 (2000)]. The present paper reports on the extension of these experimental studies to principal series lines of K broadened by K as well as Cs broadened by Cs. In addition, the broadening of some lower members of the K, Rb, and Cs principal line series due to heteroatomic interactions was investigated. The analysis of the measured satellite structures in the quasistatic line wings and their comparison to the previously published analogous data for Rb^∗+Rb system lead to the conclusion that one can expect existence of potential minima in homo- and heteroatomic alkali-metal A^∗+B systems in a wide range of principal quantum numbers, starting with K, Rb, and Cs excited to the third resonance states. The positions and strengths of the satellite structures indicate that the potential minima are due to scattering of the valence electron by ground-state perturbers.