Frequency Shifts, Line Broadenings, and Phase-Interference Effects in Rb**+Rb Collisions, Measured by Doppler-Free Two-Photon Spectroscopy

Abstract

Self-broadenings and frequency shifts of $n^{2}S$ and $n^{2}D$ Rydberg levels (up to $n\sim 70$) have been measured for rubidium in the pressure range of 3 to 100 mTorr, and the general dependence on principal quantum number $n$ has been established for this low-pressure regime. A closer examination has revealed large (almost evenly spaced) oscillations in the dependence of linewidth on principal quantum number for the ${}_{}{}^2{}_{}{}^{}S$ levels in the region of largest linewidth ($n\sim 20 \mathrm{to} 30$).