Sputtering-induced modification of the electronic properties of Ag/Cu(1 1 1)

Abstract

High-resolution electron energy loss spectroscopy has been used to study the electronic properties of Ag thin films deposited on Cu(111) and modified by Ar + sputtering. Ion sputtering strongly modifies the loss function in the region of single-particle transition as deduced from the appearance of sputtering-induced spectral features in the valence band. In contrast with unmodified Ag systems, in sputtered films the centroid of the induced charge of the surface plasmon lies in the close nearness of the jellium edge. In these modified Ag films, Landau damping processes are activated beyond a critical energy of 3.83 eV and a threshold wave-vector of 0.2 Å-1. Moreover, we found that plural plasmonic losses arose upon increasing Ar + dose. A comparison with the case of the sputtered Ag(100) surface is presented throughout the paper.

Surface plasmons at composite surfaces with diffusive charges

“…Hence the SP dispersion is negative (B < 0) if the oscillating charge is dominantly located outside the metal (z > 0) as in alkali metals 6,7 , while B > 0 if the oscillating charge is dominantly inside. In some cases the coefficient B is small and the quadratic term Ck 2 dominates the dispersion 4,14,16 , even at the lowest measurable k. From Eq. (1), B = 0 is a strong indication for a charge excitation that is highly localized at the surface, z = 0.…”

“…≡ α 2 ρ(x, 0) + α 3 j z (x, 0) p,pz>0 q W s (q, p)v z f (1) s (q) ≡ α 4 p,pz>0 q W s (q, p)2v 2 z g (1) zz (p) f 0 s (x, q) ≡ α 5 (16) Note that the difference α 3 − α 5 involves an integral over 1 − 2f 0 s (x, q), which vanishes if the surface states have an electron-hole symmetry.…”

“…Surface plasmons (SP) are an efficient tool for characterizing such surfaces [1,2] and can be used as sensitive chemical sensors and biosensors [3]. A considerable amount of data on the dispersion of SPs has been accumulated [4][5][6][7][8][9][10][11][12][13][14][15][16] on a variety of metal surfaces, clean, sputtered, or covered with thin films. These composite surfaces indicate the necessity of distinguishing between two types of charge carriers: continuous charges (CC) extending throughout the bulk and a charge layer (CL) of carriers localized at the surface.…”

Interaction of HNCO with Au(111) surfaces

“…Besides the clean Au(111), the interaction of HNCO will be examined with ion bombarded and oxygen-dosed Au(111) surfaces. It is known that low energy ion bombardment generates significant structural alterations ranging from adatoms to vacancies, which lead to the increased reactivity of the surface [36][37][38][39][40][41]. On the other hand adsorbed O adatoms on Au(111) can also enhance its reactivity towards chemisorption of different molecules [42][43][44].…”

Characterization of nanometre-scale patterns on Cu(001) and Ag(001) by means of optical spectroscopy and high-resolution electron diffraction

“…The high sensitivity of RAS for recording optical anisotropy has led to its use to monitor semiconductor growth [62], to probe surface electronic states [63], to measure morphological surface structures (i.e. steps and islands) [17] and to determine the orientation and crystalline properties of adsorbed organic molecules [20].…”