Image-Potential States Observed by Inverse Photoemission

Dose, V.; Altmann, Werner; Goldmann, A.; Kolac, U.; Rogozik, J.

doi:10.1103/physrevlett.52.1919

Cited by 203 publications

(57 citation statements)

References 11 publications

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“…[20,37] As expected for transitions into image-potential states, the dipolar axis is perpendicular to the surface resulting in more intensity in GM 70 than in GM 35 . [38] (iii) At about 1.8 eV, a new structure A appears in the h-BN/Ni(111) spectra, which we attribute to the predicted interface state of the h-BN/Ni(111) system. It is conspicuous that the shape and the energetic position of A differs in the two spectra obtained with different photon takeoff angles.…”

Section: Energy Dispersionmentioning

confidence: 99%

Exchange-split interface state at h-BN/Ni(111)

et al. 2008

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Section: Energy Dispersionmentioning

confidence: 99%

Exchange-split interface state at h-BN/Ni(111)

et al. 2008

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“…This is a standard method to identify an image potential state in IPES, and to distinguish it from other kinds of surface or bulk-related states. 24 Here, we use the work function change induced by Sn adsorption. This material forms a well-ordered pseudomorphic layer, thus avoiding scattering processes that might suppress the image potential state.…”

Section: Resultsmentioning

confidence: 99%

“…Image potential states are Rydberg series of bound states whose binding energy is given by E n = 0.85/n 2 eV, where n= 1, 2, 3,... and have been reported in many metal surfaces. 23,24,[30][31][32][33] They are pinned to the vacuum level (E vac ) and thus the energy of n= 1 image potential state is 0.85 eV below E vac . The work function of i-Al-Pd-Mn turns out to be 5± 0.15 eV, and the resulting E vac is shown by an arrow in Fig.…”

Section: Resultsmentioning

confidence: 99%

Unoccupied electronic states of icosahedral Al-Pd-Mn quasicrystals: Evidence of image potential resonance and pseudogap

et al. 2014

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We study the unoccupied region of the electronic structure of the fivefold symmetric surface of an icosahedral (i) Al-Pd-Mn quasicrystal. A feature that exhibits parabolic dispersion with an effective mass of (1.15±0.1)me and tracks the change in the work function is assigned to an image potential resonance because our density functional calculation shows absence of band gap in the respective energy region. We show that Sn grows pseudomorphically on i-Al-Pd-Mn as predicted by density functional theory calculations and the energy of the image potential resonance tracks the change in the work function with Sn coverage. The image potential resonance appears much weaker in the spectrum from the related crystalline Al-Pd-Mn surface, demonstrating that its strength is related to the compatibility of the quasiperiodic wave functions in i-Al-Pd-Mn with the free electron like image potential states. Our investigation of the energy region immediately above EF provides unambiguous evidence for the presence of a pseudogap, in agreement with our density functional theory calculations.

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“…Below, we sketch a quantum-kinetic approach to calculate s e and τ e from a simple microscopic model for the plasma boundary interaction which treats the interaction of electrons with plasma boundaries as a physisorption process [30,31,32,33,34,35,36,37,38,39,40] in the polarization-induced attractive part of the surface potential. Electron surface states [41,42,43,44,45,46,47,48,49,50,51,52,53,54,55], at most a few nm away from the boundary, will thus play a central role as will surfacebound scattering processes which control electron energy relaxation at the surface and thus electron sticking and desorption.…”

Section: −1 Imentioning

confidence: 99%

Physisorption kinetics of electrons at plasma boundaries

2009

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Abstract. Plasma-boundaries floating in an ionized gas are usually negatively charged. They accumulate electrons more efficiently than ions leading to the formation of a quasi-stationary electron film at the boundaries. We propose to interpret the build-up of surface charges at inert plasma boundaries, where other surface modifications, for instance, implantation of particles and reconstruction or destruction of the surface due to impact of high energy particles can be neglected, as a physisorption process in front of the wall. The electron sticking coefficient se and the electron desorption time τe, which play an important role in determining the quasi-stationary surface charge, and about which little is empirically and theoretically known, can then be calculated from microscopic models for the electron-wall interaction. Irrespective of the sophistication of the models, the static part of the electron-wall interaction determines the binding energy of the electron, whereas inelastic processes at the wall determine se and τe. As an illustration, we calculate se and τe for a metal, using the simplest model in which the static part of the electron-metal interaction is approximated by the classical image potential. Assuming electrons from the plasma to loose (gain) energy at the surface by creating (annihilating) electron-hole pairs in the metal, which is treated as a jellium half-space with an infinitely high workfunction, we obtain se ≈ 10 −4 and τe ≈ 10 −2 s. The product seτe ≈ 10 −6 s has the order of magnitude expected from our earlier results for the charge of dust particles in a plasma but individually se is unexpectedly small and τe is somewhat large. The former is a consequence of the small matrix elements occurring in the simple model while the latter is due to the large binding energy of the electron. More sophisticated theoretical investigations, but also experimental support, are clearly needed because if se is indeed as small as our exploratory calculation suggests, it would have severe consequences for the understanding of the formation of surface charges at plasma boundaries. To identify what we believe are key issues of the electronic microphysics at inert plasma boundaries and to inspire other groups to join us on our journey is the purpose of this colloquial presentation.PACS. 52.27.Lw Dusty or complex plasmas -52.40.Hf Plasma-material interaction, boundary layer effects -68.43.-h Chemi-/Physisorption: adsorbates on surfaces -73.20.-r Electron states at surfaces and interfaces

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Image-Potential States Observed by Inverse Photoemission

Cited by 203 publications

References 11 publications

Exchange-split interface state at h-BN/Ni(111)

Exchange-split interface state at h-BN/Ni(111)

Unoccupied electronic states of icosahedral Al-Pd-Mn quasicrystals: Evidence of image potential resonance and pseudogap

Physisorption kinetics of electrons at plasma boundaries

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