Accession Number : ADA187426

Title :   Electron Tunneling Microscopy.

Descriptive Note : Rept. for 1 Oct 86-30 Sep 87,

Corporate Author : CALIFORNIA INST OF TECH PASADENA

Personal Author(s) : Baldeschwieler, John D

PDF Url : ADA187426

Report Date : 01 Oct 1987

Pagination or Media Count : 6

Abstract : The high vacuum STM system at Caltech has been applied to study the surface structure of MoS2. The resolution in the plane of the surface is about 1A, while that normal to the surface is better than 0.1A. It is straightforward to distinguish two distinct atomic sites at this surface by tunneling microscopy, both in the conventional constant current variable height mode as well as in the variable current constant height mode. The top layer of M0S2 consists of a hexagonal lattice of sulphur atoms with 3.16A spacing. Below this plane is an identical lattice of Mo atoms laterally displaced so as to reduce the 6-fold S planar rotational symmetry to three-fold symmetry. The surface unit cell is diamond shaped with four atoms os one type (probably sulfur) at the corners. A single atom of the other type is centered in one triangular half of the cell and a hollow located in the other half. The variation in tunnel current through a series of cell diagonals and cell edges reveals a repeated pattern of three sites along the former and only simple sinusoidal modulation along the latter. Keyword: Molybdenum disulfides.

Descriptors :   *ELECTRON MICROSCOPY, *MOLYBDENUM COMPOUNDS, *SULFIDES, ATOMS, THINNESS, ELECTRONICS, TUNNELING(ELECTRONICS), HIGH VACUUM, PATTERNS, CELLS, EDGES, MODULATION, SURFACES, PLANE GEOMETRY, SULFUR, MICROSCOPY, TUNNELING, TUNNELS

Subject Categories : Inorganic Chemistry

Distribution Statement : APPROVED FOR PUBLIC RELEASE