Dispersion study of the Ag(1 1 1) surface plasmon (SP) by means of high resolution electron energy loss spectroscopy (HREELS)

Contini, R.; Layet, J. M.

doi:10.1016/0038-1098(87)90615-6

Cited by 58 publications

(12 citation statements)

References 16 publications

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“…According to experimental evidence [35][36][37] all three low index surfaces of silver exhibit linear and positive (upward) surface plasmon dispersion, in contrast to the free-electron like metal surfaces for which it is negative and well described in jellium (Je) based models [38]. If, following the suggestions of Rocca et al [37] and analyses of Feibelman [39], the bulk and surface plasmons in Ag are thought of as collective excitations split off the bottom of 4d-5s band of electronhole excitations in the interior of the metal, then the position of the effective image plane will shift to the region of 4d orbitals, i.e.…”

Section: ṽmentioning

confidence: 99%

Excitonic precursor states in ultrafast pump–probe spectroscopies of surface bands

Gumhalter

Lazić

Došlić

2010

Physica Status Solidi (b)

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Phone: þ385 1 4698 805, Fax: þ385 1 4698 889We discuss the formation and evolution of transient coherent excitonic states induced by ultrashort laser irradiation of metal surfaces supporting the surface and image potential bands (typically the low index surfaces of Cu and Ag). These states, which evolve into the image potential states in the course of screening of primary optically excited electron-hole pair, may play the role of early intermediate states in pump-probe spectroscopies of surfaces (e.g. two-photon-photoemission or sum-frequency generation) if the formation of image charge density proceeds on the time scale of the order of or longer than the pump-probe pulse duration and delay. In this regime a pump-probe experiment may yield information on the characteristics of such states rather than the states in relaxed image potential bands. Time scales of the various stages of these processes are estimated using an exactly solvable model of surface screening.1 Early time interactions of quasiparticles excited at surfaces The interpretation of excitation and detection of quasiparticles at surfaces in pump-probe experiments utilizing ultrashort laser pulses requires the assessment of quasiparticle dynamics and system relaxation from a true early evolution standpoint. While the nonadiabatic dynamics has been discussed in connection with the studies of surfaces and surface reactions by pulsed laser beams (for review see Refs. [1, 2]), the non-Markovian relaxation effects [3,4] following optical excitation of surfaces have only recently become the subject of interest and theoretical modelling [5]. Here we shall discuss these effects on the example of two-photon-photoemission (2PPE) from paradigmatic systems whose initial ground state accommodates partly occupied quasi-two-dimensional surface state bands (Q2D SS-bands) on top of the bulk valence and conduction band structure [typically on (111) surfaces of Cu and Ag]. The discussion will be focused on electronic screening processes as the dominant relaxation mechanism and in this context on the dynamics of formation of the much discussed Q2D image potential band states (IS-states) that are observed in the surface projected band gaps between the vacuum level E V and the Fermi energy E F of the substrate [6]. These bands are not incorpotated in the initial equilibrium electronic structure because they arise as a result of the response of the system to introduction of electronic charge outside the surface.In the initial step of 2PPE from surface bands [7] an electron excited out of the SS-band state by absorption of a pump pulse photon of energy v pu E V À E F will first feel the initial state effective substrate potential and the interaction with unscreened SS-hole left behind. This leads to formation of a coherent primary exciton whose bound state discrete energy levels E l < E V may form a Rydberglike series characterized by the quantum numbers l that reflect the specificities of constrained electronic motion [8][9][10]. Subsequently, the two photocreated quasipart...

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Section: ṽmentioning

confidence: 99%

Excitonic precursor states in ultrafast pump–probe spectroscopies of surface bands

Gumhalter

Lazić

Došlić

2010

Physica Status Solidi (b)

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“…The following general features emerge from the data: i) simple metals (A1, Na, K, Cs) show a negative dispersion relation [2] at small wave vector q and, accordingly, the plasma resonance of alkali metal clusters is observed to shift to lower frequencies with decreasing particle size [4]. ii) Flat surfaces and small particles of silver shown an opposite behaviour: the surface plasmon disperds towards higher frequencies [3] and the Mie resonance is blue-shifted in positive charged Ag clusters [5]. However in negative charged Ag clusters the plasma resonance is red-shifted [6].…”

Section: Introductionmentioning

confidence: 98%

“…These experiments have allowed an accurate measurement of both the volume plasmon dispersion [1] and the surface plasmon dispersion [2,3]. Recently the surface plasmon mode has been observed in small metal particles by means of fragmentation experiments [4][5][6].…”

Section: Introductionmentioning

confidence: 99%

Influence of core electrons on plasmon oscillations

Lipparini

Pederiva

1993

Z Phys D - Atoms, Molecules and Clusters

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Abstract. Core electrons constitute a polarizable background which tends to screen the plasma oscillations. The influence of core electrons on plasmon dispersion is studied with sum rule techniques. Analytical expressions are derived for the surface plasmon of flat surfaces and of small metal particles. Core polarization explains semiquantitatively the blue-shift of the surface plasmon recently observed in silver systems.

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“…Significant deviations from the dispersion of surface plasmons at jellium surfaces occur on the noble metal Ag [107,108,109,110], and the transition metals Hg [111] and Pd [297] (see Table IV). These deviations are mainly due to the presence in these metals of filled 4d and 5d bands, which in the case of Ag yields an anomalous positive and strongly crystal-face dependent dispersion.…”

Section: Occupied D-bands: Simple Modelsmentioning

confidence: 99%

“…Significant deviations from the dispersion of surface plasmons at jellium surfaces occur on Ag [107,108,109,110] and Hg [111], due to the presence of filled 4d and 5d bands, respectively, which in the case of Ag yields an anomalous positive dispersion. In order to describe the observed features of Ag surface plasmons, various simplified models for the screening of d electrons have been developed [112,113,114,115,116].…”

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confidence: 99%

Theory of surface plasmons and surface-plasmon polaritons

Pitarke¹,

Silkin²,

Chulkov³

et al. 2006

Rep. Prog. Phys.

1,333

998

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Collective electronic excitations at metal surfaces are well known to play a key role in a wide spectrum of science, ranging from physics and materials science to biology. Here we focus on a theoretical description of the many-body dynamical electronic response of solids, which underlines the existence of various collective electronic excitations at metal surfaces, such as the conventional surface plasmon, multipole plasmons, and the recently predicted acoustic surface plasmon. We also review existing calculations, experimental measurements, and applications.

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Dispersion study of the Ag(1 1 1) surface plasmon (SP) by means of high resolution electron energy loss spectroscopy (HREELS)

Cited by 58 publications

References 16 publications

Excitonic precursor states in ultrafast pump–probe spectroscopies of surface bands

Excitonic precursor states in ultrafast pump–probe spectroscopies of surface bands

Influence of core electrons on plasmon oscillations

Theory of surface plasmons and surface-plasmon polaritons

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