tile photoemission experiments with LEED and work-function mcasurenaents, it is found that the surface of indium phosphide is not stable when it is activated, i.e., the photoemission slowly changed. An cstimatc of the thermalization length is derived and the value is used to describc the discrepancy betwcen the diffusion model theory and the cxf~erimcntal results at photon energies higher than 1.5 eV, Kenn-Ho Chang and P H E Meijer, J I'ยขtc Sci Techm~l, 14 (3), 1977, 789-796. 36 3137. Auger electron spectroscopic depth profiling, techniques applied to ultrathin electrochemically deposited metal layers. (USAI The Auger electron spectroscopic depth profiling technique is applied to the study of the initial equivalent monolayer of electrodeposited Ag on thin-film Pt electrodes. The ultimate depth resolution of this technique is determined by examining ultrathin layers of Ag which have been ion deposited from a zeolite source in ultrahigh vacuum. The exponential decay apparent in the examination of such layers is explained from elementary considerations of the sputtering process. These are seen to be the resolution-limiting factor for these layers. The depth resolution is shown to be on the order of 5 ,~. Examination of monolayer and submonolayer films of Ag electrodeposited from an AgCIOt/sulfolane solution shows that there is an absorbed overlayer of S (of solvent origin) followed by the electrodeposited Ag film, which is rich in CI (of solute origin), followed by the Pt substrate, which also contains high levels of CI. The absence of underpotential deposition is clearly demonstrated. There appears to be two chemical states of CI present which are distinguished by their relative thermal stabilities. M L Knotok el al, J I/ac Sci Technol, 14 (2), 1977, 705-710. 36 3138. Evaluation of impurity and contamination levels on mica surfaces using SSIMS. (USA) Static secondary-ion mass spectrometry (SSIMS) has been used to analyze surfaces of Brazilian muscovite subjected to various standard cleaning techniques, viz., air cleavage, UHV cleavage, and UHV heating. The purpose of these experiments is to establish the surface composition and contamination state before and after application of the technique. Major contamination species are identified as hydrocarbon compounds, probably of atmospheric origin, either from carbonaceous gases or dust. UHV cleavage is established as the only method of those tried which produces a contamination-free surface. Preliminary results of UHV heat treatment of the surface are given. Results from a simultaneous SSIMS and ion cleaning experiment are used to indicate the form of the surface contamination observed. Absolute surface concentrations of common moscovite impurities in the UHV-cleaved surface are computed from SSIMS spectra and a knowledge of lattice sites occupied by the impurity atoms (as isomorphous replacements). (GB) M G Dowsett et al, J Vac Sci Technol, 14 (2), 1977, 711-717.