VELOCITY-SELECTIVE OPTICAL-PUMPING AND DARK RESONANCES IN SELECTIVE REFLECTION SPECTROSCOPY

We report an experimental investigation of selective reflection spectr a using a bichromatic field with a resonant Lambda-type coupling to th e D-1 transition of Rb vapor atoms. The reflection spectra are found t o have a more complex structure than equivalent spectra in transmissio n experiments. This structure is traced back to the effect of wall col lisions on velocity selective optical pumping and saturation processes . The,spectral line shapes are well described by a theoretical model d eveloped in the text. In addition we report the observation of dark re sonances in reflection spectroscopy.