Reflectivity and band structure of 1T-VSe2

Normal-incidence reflectivity spectra of 1T-VSe 2 have been measured at room and liquid nitrogen temperatures with E perpendicular to c and E//c, and Kramers-Kronig analysis has been carried out for the E perpendicular to c spectra over the energy range 0.6-14 eV. The formation of charge-density waves at 110K is seen to suppress the energy of the free-carrier plasma resonance and to reduce the number of free carriers to less than 0.63 per formula unit. There is good overall agreement with the band structure of Zunger and Freeman (1979); however, the results suggest the need to lower the calculated positions of the d-like bands by 0.2-0.3 eV, and the s/p-like conduction band by about 1.5 eV. The spectra also suggest that 1T-VSe 2 is probably a truly two-dimensional conductor.