Optical Properties of Ag and Cu
H. Ehrenreich, H. R. Philipp
Experimental data for the optical constants of Ag and Cu extending to 25 eV are discussed in terms of three fundamental physical processes: (1) free-electron effects, (2) interband transitions, and (3) collective oscillations. Dispersion theory is used to obtain an accurate estimate of the average optical mass characterizing the free-electron behavior over the entire energy range below the onset of interband transitions. The values are ma =1.03 ± and 0.06 for Ag and 1.42± and 0.05 for Cu. The interband transitions to 11 eV are identified tentatively using Segall's band calculations. Plasma resonances involving both the conduction band and d electrons are identified and described physically.
