"Negative-electron-affinity diamondoid monolayers as high-brilliance source for ultrashort electron pulses"

S. Roth: D. Leuenberger, J. Osterwalder, J.E. Dahl, R.M.K. Carlson, B.A. Tkachenko, A.A. Fokin, P.R. Schreiner, M. Hengsberger; Chemical Physics Letters, 07/15/10.

Additional Authors: D. Leuenberger, J. Osterwalder, J.E. Dahl, R.M.K. Carlson, B.A. Tkachenko, A.A. Fokin, P.R. Schreiner, M. Hengsberger

Abstract:

Diamondoids are nanometer-sized, hydrogen terminated diamond-like molecules consisting of fused adamantane units. The thiolated diamondoid [121]tetramantane-6-thiol shows negative electron affinity behavior, i.e. population of unoccupied states directly leads to spontaneous electron emission. We present time-resolved photoemission data from self-assembled monolayers of [121]tetramantane-6-thiol in order to shed light on the emission process: A photon energy threshold for electron emission of 5.6–5.8 eV was observed, and the electron affinity was estimated to be −0.21 to −0.57 eV for Ag and Au substrates, respectively. Electrons are emitted after excitation in the metal substrate through the molecular orbitals within a few femtoseconds.