PSEUDOMOMENTUM TRANSFER FROM EVANESCENT WAVES TO ATOMS MEASURED BY SATURATED ABSORPTION-SPECTROSCOPY

We perform saturated absorption spectroscopy using counterpropagating evanescent waves at different incident angles. The experimental result s show that a crossover resonance splits into Two resonant peaks, and the separation increases with an increase in the difference between th e incident angles of the pump and the probe evanescent waves. This ind icates that the pseudomomentum of the evanescent wave, which is the wa ve vector along the surface multiplied by (h) over bar and is larger t han the momentum in vacuum, is actually transferred to the atoms as a real recoil momentum. (C) 1998 Elsevier Science B.V.