RAMAN-INDUCED AVOIDED CROSSINGS IN ADIABATIC OPTICAL POTENTIALS - OBSERVATION OF LAMBDA 8 SPATIAL-FREQUENCY IN THE DISTRIBUTION OF ATOMS/

Chromium atoms traverse an optical potential and the resulting spatial distribution is measured by a new method. Atoms are collected on a su bstrate and an atomic force microscope is used to determine the flux a s a function of position. An unexpectedly high spatial frequency (lamb da/8) is found in the atomic distribution. This is attributed to avoid ed crossings arising from Raman coherences induced between magnetic su blevels. These results show that level crossings and nonadiabatic tran sitions can play an important role in the manipulation of atomic traje ctories by near-resonant light fields.