Electron momentum distribution in silicon

Abstract

X-ray Compton profiles of silicon were measured, using Mo Kα (Λ = 0·709 Å) and Ag Kα (0·559 Å) along the [100], [110] and [111] directions. After subtracting the 2s ²2p ⁶ Hartree-Fock core contributions in the impulse approximation (1δ² not excited the Compton profile for the four valence electrons averaged over these three directions agreed with the averaged theoretical profile calculated by Stroud and Ehrenreich (1968) and with the averaged profile determined by Erskine and McGervey (1966) from their positron annihilation angular correlation studies. The small departures from spherical symmetry in the Compton profiles did not agree with the theoretical calculations nor with the positron measurements (which agree with each other) but rather appeared to be similar to the anisotropies in the diamond Compton profile. The disparity between the x-ray and positron work may be due to the local positron shielding of the electron-electron correlation effect.