Surface plasmon dispersion at silver single-crystal surfaces

Abstract

We develop a model for the calculation of screening at the surface of single Ag crystals, including the response of both conduction and bound electrons. We obtain the electron-energy-loss spectra on the low index faces, and from it, the corresponding surface plasmon ͑SP͒ dispersion relations. Our results depend strongly on the face orientation and, for Ag͑110͒, and also on the propagation direction. With an appropriate choice of surface density profile for the conduction electrons, our model yields large positive SP dispersions, in qualitative agreement with experiment. ͓S0163-1829͑99͒11631-X͔ PHYSICAL REVIEW B 15 SEPTEMBER 1999-I VOLUME 60, NUMBER 11 PRB 60 0163-1829/99/60͑11͒/8348͑11͒/$15.00 8348There is also a coupling to the polarization p B e ϪQz m , consisting of a direct and a surface-mediated interaction. The former can be separated into a short-range contribution ͚ m e ϪQz m T J nm sr Ϸe ϪQz n T Jsr ͑24͒ and a long-range contribution ͚ m e ϪQz m T J nm lr ϭe ϪQz n ͑ T J Ͼ lr ϩnT J Ͻ lr ͒. ͑25͒Here we introduced the short-range interaction tensor 8352 PRB 60 CATALINA LÓ PEZ-BASTIDAS AND W. LUIS MOCHÁ N

Theory of surface plasmons and surface-plasmon polaritons

“…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]. Most recently, calculations have been found to yield a qualitative understanding of the existing electron energy-loss measurements by combining a self-consistent jellium model for valence 5s electrons with a so-called dipolium model in which the occupied 4d bands are represented in terms of polarizable spheres located at the sites of a semi-infinite face-cubic-centered (fcc) lattice [117].…”

Plasmonic Modes Confined in Nanoscale Thin Silver Films Deposited onto Metallic Substrates

“…22 23 The surface plasmon (SP) dispersion and the nature of the collective excitations in single-crystal Ag surfaces are well understood and there exists full agreement between experimental results [23][24][25][26][27][28] and theoretical predictions. [29][30][31][32] The interaction between s and d electrons shifts the energy of the Ag SP from 6.50 down to 3.70 eV. Furthermore, contrary to simple metals the dispersion of Ag SP was found positive.…”

“…Furthermore, contrary to simple metals the dispersion of Ag SP was found positive. [23][24][25][26][27][28][29][30][31][32] A negative dispersion on Ag systems was reported only for modified Ag single-crystal surfaces, i.e., Cl/Ag(111), 33 O/Ag(100), 34 and the sputtered and nanostructured Ag(100). 35 However, some issues are still unresolved.…”

Tuning the surface plasmon on Ag(111) by organic molecules

“…[1][2][3][4][5] The dispersion of the surface plasmon energy as a function of parallel momentum transfer (q jj ) provides rich information on the fundamental nature of the charge screening at the surface. 1, 5,6 Recently, surface plasmon based circuits have connected the fields of photonics and electronics at the nanoscale, giving rise to an exciting area for applications of surface plasmon, the so-called plasmonics. [7][8][9] It should be pointed out that the plasmonic devices are normally prepared and used in air, and the most commonly employed materials include noble metals such as Ag.…”