Accession Number : AD0684562

Title :   STUDIES OF PHYSICAL AND CHEMICAL PROPERTIES OF SOLID SURFACES.

Descriptive Note : Final rept.,

Corporate Author : SYSTEMS RESEARCH LABS INC DAYTON OHIO

Personal Author(s) : Jackson,A. G.

Report Date : NOV 1968

Pagination or Media Count : 98

Abstract : Detailed calculations of reflection coefficient of the Nb(110) surface are presented. The basis of the calculations is the McRae multiple scattering theory for low energy electron diffraction. Enough detail is presented to point out how to apply the theory for the s-wave scattering case for many metals. In essence, the method is to determine the reduced effective field by use of matrix methods. The dynamical structure factor is then found, followed by the reflection coefficient. Results of ultra-thin film studies are presented. Aspects of the tin/Nb(110) system have been studied by low energy electron diffraction techniques. The type of surface structure one obtains was found to depend upon the rate of evaporation. A diffuse phase results from rapid evaporation (> 10 layers/sec). Sn(110) or a (3x1) structure can be obtained in low rate (2 layers/sec) cases in which substrate is not heated during evaporation. Both cases produce Nb3Sn(110) structure by heating to high temperature the exact temperature depending upon the rate at which the film was formed. Characteristic energy loss measurements confirm the presence of tin in low rate case and when LEED pattern and specular intensity curve did not indicate presence of tin. This last point is briefly discussed. A low energy electron spectroscopy (LEES) apparatus is briefly described, the design of which is based upon that constructed by Propst et al. The details of operation are presented. (Author)

Descriptors :   (*CRYSTAL STRUCTURE, METAL FILMS), (*METAL FILMS, SURFACE PROPERTIES), ELECTRON DIFFRACTION, EPITAXIAL GROWTH, INELASTIC SCATTERING, WAVE FUNCTIONS, SUPERCONDUCTORS, COMPUTER PROGRAMS, NIOBIUM COMPOUNDS, TIN COMPOUNDS, ALUMINUM, TIN

Subject Categories : Physical Chemistry
      Crystallography

Distribution Statement : APPROVED FOR PUBLIC RELEASE