SPECTRAL MOMENTUM DENSITY OF ELECTRONS IN COPPER

The spectral-momentum density of electrons in a copper thin film has b een directly measured using electron momentum spectroscopy. The measur ed spectral-momentum density shows two distinct features. The first is a free-electron-like parabola with dispersion spanning 10 eV in energ y and 0.65 a.u. in momentum. The other is a weak and extended band loc ated in a narrow range of energies from about 2 to 5 eV below the Ferm i level. A spherically averaged linear muffin-tin orbital (LMTO) calcu lation of copper reproduces these features in both the dispersion patt ern and the intensity. After taking into account the elastic and inela stic multiple scattering through a Monte Carlo simulation, the agreeme nt between the calculation and the measurement is good. The measuremen t and the LMTO calculation are also compared with an available linear- augmented-plane-wave calculation for the energy-integrated electron mo mentum distribution of the valence band and the agreement is also good .