Wavelength Modulation Spectrum of Copper

The wavelength modulation spectrum of Cu is presented at 7^∘{}K in the range of 2.0<~ω<~6.0 eV. The band structure of Cu calculated by the empirical pseudopotential method is used to compute the imaginary part of the dielectric function ε₂(ω) and the logarithmic derivative of the reflectivity, R^'(ω)R(ω). Good agreement between theory and experiment is obtained at the absorption edge and at higher energies using the one-electron approximation if dipole matrix elements are calculated from wave functions including core contributions rather than the pseudowave functions. The transitions causing the structure in R^'(ω)R(ω) are identified.