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Sudden approximation in photoemission and beyond

Hedin, Lars LU and Lee, JD (2002) In Journal of Electron Spectroscopy and Related Phenomena 124(2-3). p.289-315
Abstract
The conditions behind sudden approximation are critically examined. The fuzzy band expression is derived in detail from first principles. We go beyond the sudden approximation to account for both extrinsic losses and interference effects. In an extension of earlier work we discuss both core and valence satellites including both intrinsic and extrinsic amplitudes, and high energy excitations as well as low energy electron-hole pairs. We show how the extrinsic losses in photoemission can be connected with the electron energy loss function. This is achieved by three approximations, to connect the dynamically screened potential in the bulk solid to the loss function, to account for the surface, and lastly to extrapolate zero momentum loss data... (More)
The conditions behind sudden approximation are critically examined. The fuzzy band expression is derived in detail from first principles. We go beyond the sudden approximation to account for both extrinsic losses and interference effects. In an extension of earlier work we discuss both core and valence satellites including both intrinsic and extrinsic amplitudes, and high energy excitations as well as low energy electron-hole pairs. We show how the extrinsic losses in photoemission can be connected with the electron energy loss function. This is achieved by three approximations, to connect the dynamically screened potential in the bulk solid to the loss function, to account for the surface, and lastly to extrapolate zero momentum loss data to include dispersion. The extrinsic losses are found to be weak for small loss energies. For larger loss energies the extrinsic losses can be strong and have strong interference with the intrinsic losses depending on the nature of the solid. The transition from the adiabatic to the sudden regime is discussed for atoms and localized systems and compared with the situation for solids. We argue that in solids for photoelectron energies above some 10 eV the external losses are mainly connected with spacially extended excitations. We discuss strongly correlated quasi-two-dimensional solids with Bi2212 as example, and find an asymmetric broadening of the main peak from shake up of acoustic three-dimensional plasmons. In the superconducting state the loss function is assumed to have a gap, which then leads to a peak-dip-hump structure in the photoemission spectrum. This structure is compared with a corresponding structure in tunneling. (C) 2002 Elsevier Science B.V. All rights reserved. (Less)
Please use this url to cite or link to this publication:
author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
extrinsic and intrinsic loss, energy loss function, interference, photoemission, sudden approximation
in
Journal of Electron Spectroscopy and Related Phenomena
volume
124
issue
2-3
pages
289 - 315
publisher
Elsevier
external identifiers
  • wos:000176993300016
  • scopus:0036643835
ISSN
0368-2048
DOI
10.1016/S0368-2048(02)00060-9
language
English
LU publication?
yes
id
a8b58058-0d55-408e-8658-f20ab877fe2b (old id 332693)
date added to LUP
2007-10-15 09:48:29
date last changed
2017-01-01 07:10:31
@article{a8b58058-0d55-408e-8658-f20ab877fe2b,
  abstract     = {The conditions behind sudden approximation are critically examined. The fuzzy band expression is derived in detail from first principles. We go beyond the sudden approximation to account for both extrinsic losses and interference effects. In an extension of earlier work we discuss both core and valence satellites including both intrinsic and extrinsic amplitudes, and high energy excitations as well as low energy electron-hole pairs. We show how the extrinsic losses in photoemission can be connected with the electron energy loss function. This is achieved by three approximations, to connect the dynamically screened potential in the bulk solid to the loss function, to account for the surface, and lastly to extrapolate zero momentum loss data to include dispersion. The extrinsic losses are found to be weak for small loss energies. For larger loss energies the extrinsic losses can be strong and have strong interference with the intrinsic losses depending on the nature of the solid. The transition from the adiabatic to the sudden regime is discussed for atoms and localized systems and compared with the situation for solids. We argue that in solids for photoelectron energies above some 10 eV the external losses are mainly connected with spacially extended excitations. We discuss strongly correlated quasi-two-dimensional solids with Bi2212 as example, and find an asymmetric broadening of the main peak from shake up of acoustic three-dimensional plasmons. In the superconducting state the loss function is assumed to have a gap, which then leads to a peak-dip-hump structure in the photoemission spectrum. This structure is compared with a corresponding structure in tunneling. (C) 2002 Elsevier Science B.V. All rights reserved.},
  author       = {Hedin, Lars and Lee, JD},
  issn         = {0368-2048},
  keyword      = {extrinsic and intrinsic loss,energy loss function,interference,photoemission,sudden approximation},
  language     = {eng},
  number       = {2-3},
  pages        = {289--315},
  publisher    = {Elsevier},
  series       = {Journal of Electron Spectroscopy and Related Phenomena},
  title        = {Sudden approximation in photoemission and beyond},
  url          = {http://dx.doi.org/10.1016/S0368-2048(02)00060-9},
  volume       = {124},
  year         = {2002},
}