Vacuum ultraviolet-photoemission study of some sodium tungsten bronzes,NaxWO3

Synchrotron radiation was the light source for this study. A different view of the valence and conduction bands was provided than that shown by previous x-ray photoemission data. In the present case the $p$ angular-momentum character of the electrons is emphasized more than the $d$ character. The use of a continuum light source allowed study by photon-energy-dependent spectroscopies. These made possible partial examination of the final states as well as demonstration of the nature of the Na $2p$-core excitations. The latter were found to show excitonic behavior. Effects of a possible Na deleption layer at the surface are discussed.