A MEIS STUDY OF THERMAL EFFECTS ON THE NI(111) SURFACE

Medium energy ion scattering has been used to examine the interlayer s pacings and surface vibrations at the Ni(111) surface at 300-1100 K. W e find that the surface layers, which are known to have a bulk termina ted structure at 300 K, do not exhibit a significant(> 2%) interlayer relaxation (with respect to the bulk) in the temperature range in ques tion. Monte Carlo simulations of the angular spectra show that the amp litudes of surface vibrations are larger than the bulk values by simil ar to 30-40%. No anomalies in the vibrations and interlayer spacing ne ar the Curie point have been observed. On the other hand, carbon disso lution into the bulk was seen near T-c for slightly contaminated surfa ces.