Direct Determination of Fermi Wave Vector in the Blue Bronze by Means of Angle-Resolved Photoemission Spectroscopy

The ( 01) cleavage plane of single crystals K 0.3 MoO 3 and Rb 0.3 MoO 3 have been prepared and examined using LEED, AES and angle-resolved UPS techniques. Stability conditions of the materials under the experimental probes in UHV conditions have been determined. LEED shows that the surface periodicity is the same as that of the bulk ( 01). Photoemission data show that the top of the valence band is 3.2 eV below E F . The conduction band has width and emission properties consistent with the calculated band structure. Surface states in the gap exhibit sharp angular dependence.