Resonant van der Waals repulsion between free excited atom and dielectric surface: an experimental signature

Summary form only given. The heated Cs vapor is excited by a pump beam tuned to the D/sub 1/ resonance at 894 nm and by a weak (frequency modulated) probe beam at 876 nm. The pump beam itself is sent off axis, has a large emission linewidth, and is often slightly detuned from the D/sub 1/ line, to populate the intermediate level in a broad velocity band. Experiments have been performed on several Cs vapor cells, with different input windows.