CRYSTAL AZIMUTHAL-ANGLE DEPENDENCE OF EXCITED-STATE PRODUCTION AND CORE-REARRANGEMENT PROCESSES IN NE+ SCATTERING ON AL(111)

We present the results of a study of the azimuthal-angle dependence of Ne* excited-state production in Ne+ ion scattering on an Al(111) sur face. A strong variation in the intensity of Ne*[2p(4)((3)p)3s(2)] an d Ne*[(2)p(4)(D-1)3s(2)], and most importantly in their relative inte nsity, is observed as a function of crystal azimuth. This is interpret ed as being due to a change in singlet-to-triplet atomic-core rearrang ement of excited scattered Ne projectiles as they move away from the s urface. Numerical simulations were performed and these variations in r earrangement rates were assigned to a rapid change in the perpendicula r velocity distributions of scattered particles as a function of incid ence azimuth. We conclude that nonlocalized atomic rearrangement proce sses play an important role in the singlet-to-tripler core rearrangeme nt.