Femtosecond Trapping of Free Electrons in Ultrathin Films of NaCl on Ag(100).
We report the excited-state electron dynamics for ultrathin films of NaCl on Ag(100). The first three image potential states (IPSs) were initially observed following excitation. The electrons in the spatially delocalized n = 1 IPS decayed on the ultrafast time scale into multiple spatially localized states lower in energy. The localized electronic states are proposed to correspond to electrons trapped at defects in the NaCl islands. Coverage and temperature dependence of the localized states support the assignment to surface trap states existing at the NaCl/vacuum interface. These results highlight the importance of electron trapping in ultrathin insulating layers.
Department of Chemistry, University of California at Berkeley, 419 Latimer Hall, Berkeley, California 94720, United States.|Chemical Sciences Division, Lawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, California 94720, United States.
David E
DE
Suich
Department of Chemistry, University of California at Berkeley, 419 Latimer Hall, Berkeley, California 94720, United States.|Chemical Sciences Division, Lawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, California 94720, United States.
Benjamin W
BW
Caplins
Department of Chemistry, University of California at Berkeley, 419 Latimer Hall, Berkeley, California 94720, United States.|Chemical Sciences Division, Lawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, California 94720, United States.
Alex J
AJ
Shearer
Department of Chemistry, University of California at Berkeley, 419 Latimer Hall, Berkeley, California 94720, United States.|Chemical Sciences Division, Lawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, California 94720, United States.
Charles B
CB
Harris
electron dynamics; electron localization; trap state; two-photon photoemission (TPPE); ultrathin insulating films