Valence-band electronic structure of MoS2 and Cs/MoS2(0002) studied by angle-resolved x-ray photoemission spectroscopy

The angle dependence of the valence-band photoemission from the trigonal prismatic layered MoS2 shows both the forward-scattering features normally observed in core-level photoelectron diffraction and, in addition, the initial-state orbital character associated with partially occupied, nonbonding MoIV(4dz2+4dx2-y2 +4dxy) orbitals near the top of the valence band. The difference in forward scattering between the Mo and S emitters is also used to assess relative contributions from the Mo and S atomic orbitals at specific binding energies within the valence band. Deposition of cesium (0.23 ML Cs with 1 ML equal to the Cs saturation coverage) onto the basal plane of MoS2 introduces a density of states at 1.25 eV above the top of the valence-band maximum. The intensity anisotropy for this Cs-induced valence level is interpreted via the angle dependence of the electric dipole matrix element as due to the initial-state orbital character at the bottom of the conduction band of the Cs/MoS2 heterostructure. copyright 1996 The American Physical Society