Paper SS1-FrM10
Grating-Coupled Excitation of Surface Plasmon Polariton Waves on Single Crystalline Cu(111) using Periodic Density Patterns of Rare Gas Monolayers for Adsorbate Surface Diffusion Study

Friday, October 19, 2007, 11:00 am, Room 608

Using periodic density profiles of xenon (Xe) as thin as 1 ~ 5 monolayers, we have excited and detected grating-coupled surface plasmon polariton waves (SPPW) on Cu(111) in ultrahigh vacuum. The periodic density profiles are formed by laser-induced thermal desorption with a pair of coherent laser pulses at vacuum wavelength of 0.532 microns. The periodicity of the profiles is 5.45 microns. By illuminating the xenon-density-grating-covered Cu(111) with a converging He-Ne laser covering a span of incidence angles from 66.4° to 74.4° and detecting the oblique-incidence reflectivity difference r_p/r_p0 - r_s/r_s0 vs. incidence angle with a multiple-element photodiode array, we observed the surface-plasmon resonance (SPR) peaked at the incidence angle of θ_SPR = 70.4° with a full-width at half-maximum of Δ_SPR = 0.29°. From the resonance angle θ_SPR and Δ_SPR, we have determined the optical dielectric constant of single crystalline Cu at 633 nm to be ε_Cu = -9.53 + i 0.142, markedly different from the literature values for evaporated Cu films. At elevated temperatures such that a xenon density grating on Cu(111) decays in contrast, the surface plasmon resonance as measured by r_p/r_p0 - r_s/r_s0 diminishes, reflecting the kinetic of surface diffusion of xenon on Cu(111).