Compton Profile and Electron Distribution of Iron

The Compton profile for bcc single-crystal iron has been measured using Mo and Ag $K\alpha$ x rays. The observed profile is somewhat narrower than that calculated for a free-atom Fe $3d^8$ configuration. Within the experimental uncertainty of ±3%, the profiles measured with the x-ray scattering vector along the [111] and [100] crystal directions show no anisotropy. Using the doubly and triply degenerate $3d$-orbital description, a simple model is proposed which is consistent with the results of the Compton (momentum-density), chargedensity, and unpaired-spin-density measurements.