Electron–electron coincidence spectroscopies at surfaces

Stefani, Giovanni; Iacobucci, S.; Ruocco, Alessandro; Gotter, R.

doi:10.1016/s0368-2048(02)00166-4

Cited by 20 publications

(12 citation statements)

References 30 publications

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“…The coincident photoelectron lines were narrowed compared to those of the total (noncoincidence) photoelectron spectrum and the energy position of their maximum showed, within the lifetime-broadened photoelectron linewidth, linear dispersion with the energy of the detected Auger electron [10]. This behaviour shows that the Auger process is not independent of photoemission and was interpreted as evidence of the inadequacy of the two-step description of photoexcitation and decay [10,12,17].…”

Section: Introductionmentioning

confidence: 93%

“…The Coulomb operator responsible for the Auger transition acts on the complete system involving both final electrons. The complete process can thus be considered a resonance in the double-photoionization continuum [17], which is particularly suitable in the present context where we also consider direct DPE processes. A complete description of both processes must account for the initial-state electron correlation and interaction of the final-state correlated wavefunction of the emitted electron pair with the crystal lattice.…”

Section: Introductionmentioning

confidence: 99%

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Direct and core-resonant double photoemission from Cu(001)

Riessen

Wei

Dhaka

et al. 2010

J. Phys.: Condens. Matter

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We have measured the correlated electron pair emission from a Cu(001) surface by both direct and core-resonant channels upon excitation with linearly polarized photons of energy far above the 3p threshold. As expected for a single-step process mediated by electron correlation in the initial and final states, the two electrons emitted by the direct channel continuously share the sum of the energy available to them. The core-resonant channel is often considered in terms of successive and independent steps of photoexcitation and Auger decay. However, electron pairs emitted by the core-resonant channel also share their energy continuously to jointly conserve the energy of the complete process. By detecting the electron pairs in parallel over a wide range of energy, evidence of the core-resonant double photoemission proceeding by a coherent single-step process is most strikingly manifested by a continuum of correlated electron pairs with a sum energy characteristic of the process but for which the individual electrons have arbitrary energies and cannot meaningfully be distinguished as a photoelectron or Auger electron.

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Section: Introductionmentioning

confidence: 93%

Section: Introductionmentioning

confidence: 99%

Direct and core-resonant double photoemission from Cu(001)

Riessen

Wei

Dhaka

et al. 2010

J. Phys.: Condens. Matter

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“…21 This technique is sometimes called photoelectron Auger coincidence spectroscopy (PEACS). 22 Very recently, we measured Si L 23 VV Auger electron Si 2p photoelectron coincidence spectra (Si 2p-Si L 23 VV PEACS) of Si(100)-2×1, and identified the topmostsurface Si 2p components by taking advantage of the extremely short escape depth of 1.2Å. 23 In this paper, we report on the surface-site-selective Si L 23 VV AES and Si 2p PES of clean Si(111)-7×7 measured with Si L 23 VV-Si 2p APECS and Si 2p-Si L 23 VV PEACS.…”

Section: Introductionmentioning

confidence: 99%

Surface-site-selective study of valence electronic states of a clean Si(111)-7×7 surface using SiL23VVAuger electron and Si 2
Kakiuchi
¹
,
Tahara
²
,
Hashimoto
³

et al. 2011
Phys. Rev. B

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Valence electronic states of a clean Si(111)-7×7 surface are investigated in a surface-site-selective way using high-resolution coincidence measurements of Si L 23 VV Auger electrons and Si 2p photoelectrons. The Si L 23 VV Auger electron spectra measured in coincidence with energy-selected Si 2p photoelectrons show that the valence band at the highest density of states in the vicinity of the rest atoms is shifted by ∼0.95 eV toward the Fermi level (E F ) relative to that in the vicinity of the pedestal atoms (atoms directly bonded to the adatoms). The valence-band maximum in the vicinity of the rest atoms, on the other hand, is shown to be shifted by ∼0.53 eV toward E F relative to that in the vicinity of the pedestal atoms. The Si 2p photoelectron spectra of Si(111)-7×7 measured in coincidence with energy-selected Si L 23 VV Auger electrons identify the topmost surface components, and suggest that the dimers and the rest atoms are negatively charged while the pedestal atoms are positively charged. Furthermore, the Si 2p-Si L 23 VV photoelectron Auger coincidence spectroscopy directly verifies that the adatom Si 2p component (usually denoted by C 3 ) is correlated with the surface state just below E F (usually denoted by S 1 ), as has been observed in previous angle-resolved photoelectron spectroscopy studies.

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“…ble to "conventional" spectroscopies. One exciting direction is the implementation of "coincidence" experiments, such as Auger-photoelectron coincidence spectroscopy (APECS) (Haak et al, 1978;Stefani et al, 2002), which should be revisited with the advent of improved photoemission detection technology. As mentioned above, the principal issue with such experiments is their relatively poor resolution, mainly limiting the method to getting information on the correlation hole around an electron (Schumann et al, 2007).…”

Section: Prospects For Future Developmentsmentioning

confidence: 99%