Nonequilibrium Band Mapping of Unoccupied Bulk States below the Vacuum Level by Two-Photon Photoemission

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 an...

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Bibliographic Details
Published in:Physical review letters 2010-07, Vol.105 (1)
Main Authors: Johnson, P.D., Hao, Z., Dadap, J.I., Knox, K.R., Yilmaz, M.B., Zaki, N., Osgood, R.M.
Format: Article
Language:English
Subjects:
bulk electronic structure
COPPER
ELECTRONIC STRUCTURE
MATERIALS SCIENCE
particle-hold asymmetry
PHOTOEMISSION
PHOTONS
two-photon photoemission
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Summary: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}{omega}, are in excellent agreement with tight-binding band-structure calculations. The variation of the final-state energy with {h_bar}{omega} has a measured slope of -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}k{perpendicular} in 2PPE.
ISSN:0031-9007
1079-7114