Insight on the interaction between image potential state and<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>π</mml:mi></mml:math>bands in graphite

Abstract

We demonstrate that the electron density of the light-populated image potential states in graphite reaches its maximum when the photon energy of ultrashort laser pulses is resonant with the \ensuremath{\pi}\ensuremath{-}\ensuremath{\pi}* band gap at the M point of the Brillouin zone. This unexpected behavior, as shown by the nonlinear photoelectron spectroscopy data, is assisted by the onset of a strong light-induced interaction between the \ensuremath{\pi} bands and the image potential states. This finding suggests the possibility of exploring new photochemical processes at the graphite surface and related compounds.