Electronic Excitations in Metals and at Metal Surfaces

Chulkov, Eugene V.; Borisov, Andrei G.; Gauyacq, J.P.; Sánchez‐Portal, Daniel; Silkin, Viatcheslav M.; Zhukov, V. P.; Echenique, Pedro M.

doi:10.1021/cr050166o

Cited by 233 publications

(223 citation statements)

References 500 publications

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“…The details of the WPP method can be found elsewhere. 22,23 Here we only give the aspects specific for the present study. In brief, the one-electron wave packet incident from the STM tip is propagated through the junction by solving the time-dependent Schrödinger equation (TDSE).…”

Section: Theoretical Methodsmentioning

confidence: 99%

“…The intensity of the peaks, on the other hand, is given by the overlap between the resonance wave function and the initial state used in the WPP. 23 A simple comparison between the clean surface [panel (a)] and ad-island results [panels (b) and (c)] allows one to assign the different resonances (in particular, to reveal the island-localized states) and their evolution upon the change of the experimental conditions. Thus, the additional bright lines that appear in the calculated PDOS(E,V ) for the island on top of the metal surface [panels (b) and (c)] correspond to island-induced states whose energies are not very close to the other FER's, as compared to their width.…”

Section: Theoretical Methodsmentioning

confidence: 99%

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Localization, splitting, and mixing of field emission resonances induced by alkali metal clusters on Cu(100)

et al. 2011

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We report on a joint scanning tunneling microscopy (STM) and theoretical wave packet propagation study of field emission resonances (FER's) of nanosized alkali metal clusters deposited on a Cu(100) surface. In addition to FER's of the pristine Cu(100) surface, we observe the appearance of island-induced resonances that are particularly well resolved for STM bias voltage values corresponding to electron energies inside the projected band gap of the substrate. The corresponding dI/dV maps reveal island-induced resonances of different nature. Their electronic densities are localized either inside the alkali cluster or on its boundaries. Our model calculations allow us to explain the experimental results as due to the coexistence and mixing of two kinds of island-induced states. On the one side, since the alkali work function is lower than that of the substrate, the nanosized alkali metal clusters introduce intrinsic localized electronic states pinned to the vacuum level above the cluster. These states can be seen as the FER's of the complete alkali overlayer quantized by the cluster boundaries. On the other side, the attractive potential well due to the alkali metal cluster leads to two-dimensional (2D) localization of the FER's of the Cu(100) surface, the corresponding split component of the resonances appearing below the bottom of the parent continuum. Our main conclusions are based on the attractive nature of the alkali ad-island potential. They are of general validity and, therefore, significant to understand electron confinement in 2D.

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Section: Theoretical Methodsmentioning

confidence: 99%

Section: Theoretical Methodsmentioning

confidence: 99%

Localization, splitting, and mixing of field emission resonances induced by alkali metal clusters on Cu(100)

et al. 2011

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“…Although energy-relaxation mechanisms have been theoretically intensively investigated 19 , experimentally they are usually summarized within a single parameter: the aforementioned lifetime 17 , which corresponds to a non-zero imaginary part of the quasiparticle self-energy. To investigate many-body effects in more detail, recent experimental and theoretical efforts aimed at using QPI to probe both the real and imaginary part of the selfenergy, an approach which allowed to visualize the presence of band-dispersion renormalization effects [20][21][22] .…”

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confidence: 99%

Direct observation of many-body charge density oscillations in a two-dimensional electron gas

et al. 2015

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Quantum interference is a striking manifestation of one of the basic concepts of quantum mechanics: the particle-wave duality. A spectacular visualization of this effect is the standing wave pattern produced by elastic scattering of surface electrons around defects, which corresponds to a modulation of the electronic local density of states and can be imaged using a scanning tunnelling microscope. To date, quantum-interference measurements were mainly interpreted in terms of interfering electrons or holes of the underlying band-structure description. Here, by imaging energy-dependent standing-wave patterns at noble metal surfaces, we reveal, in addition to the conventional surface-state band, the existence of an 'anomalous' energy band with a well-defined dispersion. Its origin is explained by the presence of a satellite in the structure of the many-body spectral function, which is related to the acoustic surface plasmon. Visualizing the corresponding charge oscillations provides thus direct access to many-body interactions at the atomic scale.

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“…29,38,53 We use a well established approach where the electron-electron decay rate of excited states is performed at¯ point (k = 0) by projecting the imaginary part of the self-energy onto the corresponding wave function. 30,45 In the present symmetry, we have…”

Section: B Many-body Calculation Of the Decay Ratesmentioning

confidence: 99%

“…27,28 The lifetime sets the duration of the excitation and, when combined with the group velocity, it also determines the spatial range of the excitation. For metals and metallic nanostructures at surfaces, several decay channels determine the dynamics of excited electrons for which the total decay rate (proportional to the inverse of the lifetime τ ) can be expressed as a sum of different contributions: 29,30 =h/τ = γ 1e + γ e-e + γ e-ph + γ def .…”

Section: Introductionmentioning

confidence: 99%

Quantum-well states with image state character for Pb overlayers on Cu(111)

et al. 2012

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We study theoretically the quantum well states (QWSs) localized in Pb overlayers on Cu(111) surface. Particular emphasis is given to the states with energies close to the vacuum level. Inclusion of the long-range image potential tail into the model potential description of the system allows us to show the effect of hybridization between QWSs and image potential states (ISs). The particle-in-a-box energy sequence characteristic for QWSs evolves into the Rydberg series converging towards the vacuum level. The electron density of the corresponding states is partially moved from inside the metal overlayer into the vacuum. The decay rates due to the inelastic electron-electron scattering decrease with increasing energy, opposite to "conventional" QWSs and similar to the ISs. Many-body and wave packet propagation calculations of the inelastic decay rates are supplemented by simple analysis based on the phase accumulation model and wave-function penetration approximation. This allows an analytical description of the dependence of the QWS/ISs hybridization on different parameters and, in particular, on the overlayer thickness.

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Electronic Excitations in Metals and at Metal Surfaces

Cited by 233 publications

References 500 publications

Localization, splitting, and mixing of field emission resonances induced by alkali metal clusters on Cu(100)

Localization, splitting, and mixing of field emission resonances induced by alkali metal clusters on Cu(100)

Direct observation of many-body charge density oscillations in a two-dimensional electron gas

Quantum-well states with image state character for Pb overlayers on Cu(111)

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