Quantitative measurement of the spectral function of aluminum and lithium by electron momentum spectroscopy

We present measurements of the spectral function of aluminum and lithium using high-energy electron momentum spectroscopy. For aluminum the quasiparticle peaks show clear asymmetries and significant satellite intensity that extends over a wide region to larger binding energies. The intensity distribution is not well described by band structure calculations. These data are described only by calculations based on the manybody cumulant expansion scheme. The measured momentum distribution at the Fermi level agrees with the theoretical one within 0.03 a.u. For lithium a bandwidth of 3.0 eV is obtained.