Zhang, Chang-HuaThumm, Uwe P. E.2013-04-122013-04-122011-12-14http://hdl.handle.net/2097/15501We investigate streaking time delays in the photoemission from a solid model surface as a function of the degree of localization of the initial-state wave functions. We consider a one-dimensional slab with lattice constant a[subscript latt] of attractive Gaussian-shaped core potentials of width σ. The parameter σ/a[subscript latt] thus controls the overlap between adjacent core potentials and localization of the electronic eigenfunctions on the lattice points. Small values of σ/a[subscript latt]≪1 yield lattice eigenfunctions that consist of localized atomic wave functions modulated by a “Bloch-envelope” function, while the eigenfunctions become delocalized for larger values of σ/a[subscript latt]≳0.4. By numerically solving the time-dependent Schrödinger equation, we calculate photoemission spectra from which we deduce a characteristic bimodal shape of the band-averaged photoemission time delay: as the slab eigenfunctions become increasingly delocalized, the time delay quickly decreases near σ/a[subscript latt]=0.3 from relatively large values below σ/a[subscript latt]∼0.2 to much smaller delays above σ/a[subscript latt]∼0.4. This change in wave-function localization facilitates the interpretation of a recently measured apparent relative time delay between the photoemission from core and conduction-band levels of a tungsten surface.en-US©2011 American Physical Society. This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s).Wave-function localizationPhotoemissionArticle (publisher version)