Photoemission of Holes from Metals into Anthracene

Abstract

Photoemission of holes from metal electrodes into anthracene has been observed for Au, Ag, Al, Pb, and Mg. The photoemission of electrons into the anthracene from these metals could not be observed. From the variation of the photoemission threshold for holes with the work function of the metal a value of 5.80±0.34 eV was obtained for the energy of the valence band below the vacuum level; this value agrees with that determined by photoemission of electrons from anthracene into vacuum. The spectral response of the photoemission is complex; it appears to result from photoemission into a system of narrow bands arising from the interaction of molecular vibrations with a narrow electronic band. The experiment indicates that the energy bands are under 0.1 eV in width, as predicted by theory, and are broadened by vibrational overlap.