OBSERVATION OF A FLUCTUATING CHARGE-DENSITY-WAVE IN THE UNOCCUPIED ELECTRONIC-STRUCTURE OF (TASE4)(2)I

We report momentum-resolved inverse-photoemission measurements from a quasi-one-dimensional metal, (TaSe4)(2)I. Measurements were performed above (300 K) and below (100 K) the Peierls transition temperature (26 3 K). No change in the spectra is observed that could be associated wi th the phase transition. The mainly Ta-Sd-derived conduction bands dis play, on the whole, little dispersion. In line with direct photoemissi on studies, we do not observe a Fermi edge when the material is measur ed in its metallic phase. We do, however, observe a state just above E (F) that exhibits significant dispersion along the direction of the co nducting chains. This dispersing band is compared with previously publ ished direct photoemission data. The comparison supports the existence of a fluctuating charge-density wave, and we suggest that this is the cause for the lack of a metallic Fermi edge from this material.