Optical measurements of the surface plasmon of copper

The optical properties of the noble metal copper are determined by computer fitting the experimentally obtained attenuated total internal reflection (ATR) spectra of its surface plasmon in the visible spectral region (0.42 to 0.63 μm). The dispersion curves of the surface plasmon resonance of copper are determined; they show that the resonance exists on the steep absorption edge of ϵ2 at 2.16 eV. This absorption edge, which is due to the d‐band to Fermi level transition, causes the large shift in the location of the surface plasmon excitation from ϵ 1 (ω s ) = −1 to ϵ 1 (ω s ) = −4.7 and causes the true resonance to occur in the complex frequency plane.