Nonequilibrium Band Mapping of Unoccupied Bulk States below the Vacuum Level by Two-Photon Photoemission
- Center for Integrated Science and Engineering, Columbia University, New York, New York 10027 (United States)
- Department of Condensed Matter and Materials Science, Brookhaven National Laboratory, Upton, New York 11973 (United States)
We demonstrate angle-resolved, tunable, two-photon photoemission (2PPE) to map a bulk unoccupied band, viz. the Cu sp band 0 to 1 eV below the vacuum level, in the vicinity of the L point. This short-lived bulk band is seen due to the strong optical pump rate, and the observed transition energies and their dispersion with photon energy ({h_bar}/2{pi}){omega}, are in excellent agreement with tight-binding band-structure calculations. The variation of the final-state energy with ({h_bar}/2{pi}){omega} has a measured slope of {approx}1.64 in contrast to values of 1 or 2 observed for 2PPE from two-dimensional states. This unique variation illustrates the significant role of the perpendicular momentum ({h_bar}/2{pi})k{sub perpendicular} in 2PPE.
- OSTI ID:
- 21410464
- Journal Information:
- Physical Review Letters, Vol. 105, Issue 1; Other Information: DOI: 10.1103/PhysRevLett.105.017602; (c) 2010 The American Physical Society; ISSN 0031-9007
- Country of Publication:
- United States
- Language:
- English
Similar Records
Direct comparative study on the energy level alignments in unoccupied/occupied states of organic semiconductor/electrode interface by constructing in-situ photoemission spectroscopy and Ar gas cluster ion beam sputtering integrated analysis system
Intensity oscillations in the inverse photoemission cross section of an unoccupied surface state on Cu(001)