Scattering of electrons on the Cu(001) surface by Co adatoms

Hirschmann, Markus; Fauster, Thomas

doi:10.1007/s00339-007-4050-5

Cited by 9 publications

(6 citation statements)

References 31 publications

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“…This would open the possibility to describe elastic interband scattering 15 or dephasing in quantum beats patterns. 11,65 The main purpose of this work was to explore the time range of exponential decay for elastic electron scattering by random adsorbates, viz. the lifespan of standard quasiparticle behavior.…”

Section: Discussionmentioning

confidence: 99%

Nonadiabatic dynamics of electron scattering from adsorbates in surface bands

et al. 2008

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We present a comparative study of nonadiabatic dynamics of electron scattering in quasi-two-dimensional surface band which is induced by the long-range component of the interactions with a random array of adsorbates. Using three complementary model descriptions of intraband spatiotemporal propagation of quasiparticles that go beyond the single-adsorbate scattering approach we are able to identify distinct subsequent regimes of evolution of an electron following its promotion into an unoccupied band state: ͑i͒ early quadratic or ballistic decay of the initial-state survival probability within the Heisenberg uncertainty window, ͑ii͒ preasymptotic exponential decay governed by the self-consistent Fermi golden rule scattering rate, and ͑iii͒ asymptotic decay described by a combined inverse power-law and logarithmic behavior. The developed models are applied to discuss the dynamics of intraband adsorbate-induced scattering of hot electrons excited into the n = 1 image-potential band on Cu͑100͒ surface during the first stage of a two-photon photoemission process. Estimates of crossovers between the distinct evolution regimes enable assessments of the lifespan of a standard quasiparticle behavior and thereby of the range of applicability of the widely used Fermi golden rule and optical Bloch equations approach for description of adsorbate-induced quasiparticle decay and dephasing in ultrafast experiments.

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Section: Discussionmentioning

confidence: 99%

Nonadiabatic dynamics of electron scattering from adsorbates in surface bands

et al. 2008

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“…Data for scattering rates have been obtained for Cu and Co adatoms on the Cu(001) surface [25,48]. The agreement for the inelastic scattering rates is excellent.…”

Section: Scattering By Adatomsmentioning

confidence: 98%

Electron Dynamics in Image Potential States at Metal Surfaces

Fauster

2010

Dynamics at Solid State Surfaces and Interfaces

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Electron dynamics describes the temporal evolution of an electronic state due to interactions with particles or quasiparticles. The ground state of the system is characterized by the stationary states whose time dependence is determined by the energy of the state. In the present context, we consider an excited electron at the surface, for example, in a surface or adsorbate state. On its relaxation path to the ground state (or thermal equilibrium) it is going to be scattered and the possible processes can be divided into the following categories:. Electron-electron scattering: This most important process for energy relaxation leads to decay into bulk or surface states at lower energy with simultaneous creation of an electron-hole pair. The coupling to the electronic system can also include other quasiparticles such as excitons, plasmons, and magnons that are not covered in this chapter. . Electron-phonon scattering: This scattering process mainly changes the direction of the electron motion and embraces both scattering to bulk bands and scattering within the surface state band. The energy loss is usually rather small compared to electron-electron scattering. Temperature is a convenient control of electron-phonon scattering. . Electron defect scattering: Real surfaces contain always a nonnegligible amount of defects, such as steps or impurity atoms. The associated electron defect scattering mainly changes the electron momentum leaving the energy almost unchanged. In many aspects, it is similar to electron-phonon scattering. Electron defect scattering can be identified by controlling the defect density.Image potential states [1] are a special class of surface states that exist on many metal surfaces (see chapter 3 of volume 2). The small binding energies relative to the vacuum level point to a weak coupling to the metal. Correspondingly, image potential states can have relatively long lifetimes (>10 fs) and can conveniently be studied with

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“…A sequence of 2PPE studies of electron scattering from adsorbates in image potential bands on Cu(100) 8–11 have revealed the effect of defects on hot electron dynamics in quasi‐two‐dimensional (Q2D) states. Quite generally, since the momentum K is conserved in optical transitions, the electron and hole excited in the first step of a 2PPE process start to propagate coherently with opposite momenta in the respective bands n and n ′ (for a review of the theory of 2PPE see Ref.…”

Section: Introductionmentioning

confidence: 99%

“…In this work, we focus on the theoretical interpretation of selected experimental results reported in Refs. 8–11 using the propagator formalism adapted to the studies of electron scattering by localized defects 26.…”

Section: Introductionmentioning

confidence: 99%

Electron scattering by random adsorbates: A tunable decoherence mechanism in surface bands

Marion

Gumhalter

2012

Physica Status Solidi (b)

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Mechanisms of electron decoherence at surfaces are manifold as they may originate from the various complex interactions of electrons with the static crystal structure and dynamical degrees of freedom of the environment. Decoherence effects manifest themselves in the spectroscopic data in a convoluted fashion and it is usually hard or even impossible to fully disentangle them from each other because of the lack of control of underlying mechanisms by the external observer. However, electronic propagation in quasi-two-dimensional image potential bands (IS-bands) on flat low index surfaces of some metals is subject to an efficient decoherence mechanism that can be controlled externally by careful preparation of the surface. By dosing the concentration (i.e. the coverage) of adsorbates on clean surfaces, which act as randomly distributed scattering centres, one can tune the strength of incoherent IS-electron scattering from defects. Such processes in IS-bands on Cu(100) surface have been investigated by two-photon-photoemission (2PPE) spectroscopy and interpreted using Fermi golden rule approach to calculation of the quasiparticle decay rates and scattering cross sections. However, these results could reproduce the experimental data only in a limited energy interval. Here, we employ the description of electron decoherence in IS-bands based on the propagator approach and infrared renormalization of quasiparticle self-energy and demonstrate that it gives a very good agreement between the theoretical and experimental results for the cross sections. This enables us to discuss the temporal stages of electron dynamics and decoherence in the intermediate states of 2PPE spectroscopy of surface bands. 1 Introduction Owing to the versatility of application modes and high resolution in the energy and time domain the two-photon photoemission (2PPE) spectroscopy has emerged as one of the most powerful tools for the investigation of the electronic structure of gas phase and condensed matter systems. In the past two decades, the applications of 2PPE to solids have provided valuable information on electron dynamics and energetics at surfaces and interfaces [1][2][3][4]. In 2PPE spectroscopy of surface bands, the first laser pulse (pump pulse) excites an electron from an initial occupied state below the Fermi energy E F into an unoccupied image potential state below the vacuum level E V . The population and dynamics of this intermediate excited electron state is then probed by the second pulse, which lifts the electron to a state above E V where its energy and momentum K parallel to the surface are measured. Thereby one obtains information on the properties of the

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Scattering of electrons on the Cu(001) surface by Co adatoms

Cited by 9 publications

References 31 publications

Nonadiabatic dynamics of electron scattering from adsorbates in surface bands

Nonadiabatic dynamics of electron scattering from adsorbates in surface bands

Electron Dynamics in Image Potential States at Metal Surfaces

Electron scattering by random adsorbates: A tunable decoherence mechanism in surface bands

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