Abstract
Two-photon photoemission spectroscopy (2 PPES) has been applied to benzene adsorbed Cu(111) surface and to Si(001) surface. 2 PPES for benzene adsorbed Cu(111) surface has revealed the adsorption induced bonding and antibonding states and the image state. Resonance width between the bonding state and the image state is found to be very narrow, about 0.1 eV full width at half maximum. Sharp resonant photoexcitaion has also been found for Si(001) bulk bands. These results demonstrate the capability of 2 PPES in determining pairs of occupied and unoccupied states. Importance of fine wavelength tuning in 2 PPES is emphasized.
