3D-TO-2D TRANSITION BY CS INTERCALATION OF VSE2

Angle-resolved photoemission spectroscopy has been employed to study i n situ intercalation of the layered compound VSe2 with Cs. The results show that the valence band structure of VSe2, which initially is of 3 D character, is transformed to become essentially 2D upon Cs intercala tion. The changes, which go far beyond the rigid-band model, are succe ssfully reproduced by self-consistent linear-augmented-plane-wave calc ulations. This is the first report of a UHV compatible system where th e dimensionality of the electronic structure can be controlled in situ .