Abstract
We demonstrate the contribution of coherent excitation pathways in three-photon photoemission from Cu(001). We identify separate peaks in the photoelectron spectra as originating from two specific bands that are excited at different points via the same unoccupied image-potential state. By model calculations we show that our experimental observations impose lower limits on the relevant -hole dephasing time on the order of 10–20 fs. Our findings suggest extensions to future studies in electronic structure mapping with tunable laboratory and free-electron laser sources, exploiting possible multiphoton resonances between occupied bulk and unoccupied surface states.
- Received 23 July 2009
DOI:https://doi.org/10.1103/PhysRevB.80.155128
©2009 American Physical Society