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Atomic force microscope measurements of elastic-plastic indentation into an F e -3 wt. % Si single crystal showed that the volume displaced to the surface is nearly equal to the volume of the cavity. The surface displacement profiles and plastic zone size caused by a 69 nm penetration of a Vickers diamond tip are reasonably represented by an elastic-plastic continuum model. Invoking conservation of volume, estimates of the number of dislocations emanating from the free surface are reasonably consistent with the number of dislocations that have formed in the plastic zone to represent an average calculated plastic strain of 0.044.

Photoelectron spectroscopy using x rays and synchrotron radiation was used to examine surface bonding and overlayer growth modes when the representative metals Ti, Cr, Au, La, and In were deposited onto thin films of pure C60. None of these metals intermixed with C60 or formed bulk metal-fulleride compounds. Instead, metallic clusters were produced when Au, Cr, and In atoms were condensed on C«. For Ti and La, the first layer formed as a monolayer but subsequent depositions produced clusters.The tendency to form a single layer for Ti and La reAects the hybridization of metal d and fullerene p orbitals, as with bulk carbides. In addition, limited amounts of metal carbide formation was evident for overlayers of Ti, La, and Cr due to some disruption of C«.

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Studies of photoinduced oxidation of physisorbed 02 on GaAs(110) at 25 K show that the surface reaction rate is strongly dependent on photon energy and substrate doping type. With 1.7-eV photon irradiation, the reaction cross section is 6.1 & 10 cm for n-type GaAs and -7 times higher for p-type GaAs. With 1.97-eV photon irradiation, the reaction cross section is 1.5x10 cm for n-type GaAs and -8 times higher for p-type GaAs. We show that the energy distribu-