Femtosecond Studies of Electron Dynamics at Interfaces

Ge, Nien‐Hui; Wong, C.; Harris, Charles B.

doi:10.1021/ar980138a

Cited by 65 publications

(71 citation statements)

References 42 publications

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“…In the presence of adsorbates that do not introduce unoccupied electronic levels in the energy range of the image-potential states, the wave functions of the latter will retain their simple hydrogenic character, but will be repelled from the metal. Systems with such properties that have been studied by time-resolved 2PPE include Xe/Ag(1 1 1) [258,259], alkanes/Ag(1 1 1) [260,261], Xe/Cu(1 1 1) [262,263], O 2 /Xe/ Cu(1 1 1) [264], N 2 /Cu(1 1 1) [263], N 2 /Xe/Cu(1 1 1) [263], naphthalene/Cu(1 1 1) [265], Xe/ Ru(0 0 0 1) [266,267] and Ar/Cu(1 0 0) [268,269]. Data obtained for the two latter systems are shown as examples in Figs.…”

Section: Decoupling By Spacer Layersmentioning

confidence: 99%

Decay of electronic excitations at metal surfaces

Echenique

Berndt

Chulkov

et al. 2004

Surface Science Reports

438

403

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Section: Decoupling By Spacer Layersmentioning

confidence: 99%

Decay of electronic excitations at metal surfaces

Echenique

Berndt

Chulkov

et al. 2004

Surface Science Reports

438

403

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“…where η is given in equation (16). Since the nonlinear susceptibility χ (2) and hence P (2) contains three dipole matrix elements, the reducible contributions to the photoelectron current are of higher order in dipole matrix elements and are thus usually small.…”

Section: Two-photon Photoemissionmentioning

confidence: 99%

Response theory for time-resolved second-harmonic generation and two-photon photoemission

Timm

2004

J. Phys.: Condens. Matter

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A unified response theory for the time-resolved nonlinear light generation and two-photon photoemission (2PPE) from metal surfaces is presented. The theory allows one to describe the dependence of the nonlinear optical response and the photoelectron yield, respectively, on the time dependence of the exciting light field. Quantum-mechanical interference effects affect the results significantly. Contributions to 2PPE due to the optical nonlinearity of the surface region are derived and shown to be relevant close to a plasmon resonance. The interplay between pulse shape, relaxation times of excited electrons, and band structure is analysed directly in the time domain. While our theory works for arbitrary pulse shapes, we mainly focus on the case of two pulses of the same mean frequency. Difficulties in extracting relaxation rates from pump-probe experiments are discussed-for example due to the effect of detuning of intermediate states on the interference. The theory also allows one to determine the range of validity of the optical Bloch equations and of semiclassical rate equations, respectively. Finally, we discuss how collective plasma excitations affect the nonlinear optical response and 2PPE.

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“…[10][11][12][13][14] In many cases, this results in a drastic increase of the lifetimes. [15][16][17][18] Rare-gas layers are, in particular, attractive for this purpose, since they interact only weakly with the underlying substrate and can be grown with very high order on most flat metal substrates. 19,20 For the typical excitation energies of image-potential states, rare-gas layers do not provide additional decay channels so that the main processes behind the population decay of the imagepotential states are the same as for clean surfaces.…”

Section: Introductionmentioning

confidence: 99%

Momentum-resolved electron dynamics of image-potential states on Cu and Ag surfaces

et al. 2012

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The dependence of the inelastic lifetime of electrons in the first n = 1 image-potential state of clean and rare-gas covered Ag(111), Cu(111), and Cu(100) surfaces on their momentum parallel to the surface has been studied experimentally by means of time-and angle-resolved two-photon photoemission spectroscopy (2PPE) and theoretically by calculations based on the many-body theory within the self-energy formalism. Similar to the previously studied clean Cu(100) surface, the theoretical results are in excellent agreement with the experiment findings for Cu(111). For Ag(111), the theory overestimates the decay rate and its momentum dependence, which is attributed to the neglect of surface plasmon excitations. With increasing parallel momentum, the n = 1 state shifts out of the projected bulk band gap on both surfaces and turns into an image-potential resonance. This opens an additional decay channel by resonant electron transfer into the bulk, which is theoretically treated by the application of the wave packet propagation approach. The expected stronger increase of the decay rate upon crossing the edge of the band gap, however, is not observed in the experiment. The decoupling of the image-potential states from the metal surface upon adsorption of rare-gas layers results in a decrease of the decay rate as well as of its momentum dependence by a similar factor, which can be successfully explained by the change of interband and intraband contributions to the total decay rate.

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Femtosecond Studies of Electron Dynamics at Interfaces

Cited by 65 publications

References 42 publications

Decay of electronic excitations at metal surfaces

Decay of electronic excitations at metal surfaces

Response theory for time-resolved second-harmonic generation and two-photon photoemission

Momentum-resolved electron dynamics of image-potential states on Cu and Ag surfaces

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