Analysis of spectral features of the optical constants of fullerene and halogen-fullerene films near the absorption edge

This paper reports on measurements of IR spectra and of the extinction coefficient in the 1.2-to 4.2-eV range made on C₆₀Br_x films and compared with those for pure C₆₀ films. The modification of the electronic spectrum near the absorption edge is connected with differences in the film structure and with suppression of charge-transfer excitons. The C₆₀Br_x films exhibit additional absorption below the fundamental absorption edge of C₆₀.