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Call number: LD2668 .T4 1963 W87 / Master of Science

No description available.

No description available.

Copper and silver films of various thicknesses were deposited at a rapid rate, from four to twenty-five seconds, on glass substrates in ultra high vacua at pressures of 10⁻⁸ torr or lower. Their optical properties, reflectivity, transmissivity and absorptivity, were determined in vacua and in air by direct measurement using photomultiplier tubes. All the measurements were made at nearly normal incidence with a monochromatic light beam of wavelength 4358 A. It was found that the reflectivity of films of both copper and silver decreased as they were exposed to air. The change took place in equal steps. Under the same circumstances, transmissivity increased but in a less regular way. Absorption changed in a most irregular fashion; no pattern could be established. From this study of optical properties, the layer formation on fresh, clean surfaces of copper and silver caused by the air molecules was quite evident. In the case of copper, there may be one or two layers depending on the thickness of the film. They are formed primarily by cuprous oxide. In the case of silver the layer was attributed to chemisorption. Even though there was some indication that more than one layer was formed, the evidence was not conclusive. / Master of Science

Concentration-versus-depth profiles have been calculated for Ti and C in Ti-implanted 52100 steel. A computer formalism was developed to account for diffusion and mixing processes, as well as sputtering and lattice dilation. A Gaussian distribution of Ti was assumed to be incorporated at each time interval. The effects of sputtering and lattice dilation were then included by means of an appropriate coordinate transformation. C was assumed to be gettered from the vacuum system in a one-to-one ratio with the surface Ti concentration up to a saturation point. Both Ti and C were allowed to diffuse. A series of experimental (Auger) concentration-versus-depth profiles of Ti implanted steel were analyzed using the above-mentioned assumptions. A best fit procedure for these curves yielded information on the values of the sputtering yield, range and straggling, as well as the mixing processes that occur during the implantation. The effective diffusivity of Ti was found to be 6x10⁻¹⁵ cm²/sec, a value that is consistent with the cascade mixing mechanism. The effective diffusivity of C was found 6x10⁻¹⁵ cm²/sec, and the sputtering yield by Ti atoms was best fit by a value of about 2. The observed range and straggling values were in very good agreement with the values predicted by existing theories, so long as the lattice was allowed to dilate. / M.S.