Electronic Structure and Lubrication Properties of MoS2: A Qualitative Molecular Orbital Approach.

摘要

The electronic structure of the solid lubricant material MoS2 is described by a qualitative molecular orbital (MO) model that is based on the D2h symmetry of the Mo(S)6 unit in the crystal. The MO model is used to assign peaks in the valence-level photoelectron spectrum (VLPS) and the electron energy loss spectrum of MoS2(0001) and to interpret the effects of ion bombardment (IB) of this surface on its electronic structure. The dependence of VLPS peak intensities on excitation energy is used to assign the energy levels in the MO diagram. Variations in crystal lattice spacing within sputter-deposited MoS2 films are explained in terms of electron density arguments. Structural information, together with information on surface bonding and on adhesion from the IB studies, aids in predicting the lubrication performance of these films. It is proposed that the highest occupied orbital for MoS2 is an A1 nonbonding orbital and that important film properties, such as adhesion to substrates and friction within the film, can be manipulated by altering the electron occupancy of this orbital. Keywords: Solid lubricants; MoS 2molybdenum disulfide; Electronic structure. (JHD)