The effect of crystallography on the Hg 5 d branching ratios

The Hg 5d5/2 and 5d3/2 cross sections and branching ratios were measured in the photon energy range between 26 and 105 eV for Hg overlayers on Ag (100) and Cu (100). The branching ratios deviate from the nonrelativistic statistical value of 1.5, reaching values of 8.0. Data are presented that establish a direct relationship between the branching ratio and the long-range crystallographic structure of the Hg overlayers. This relationship is a consequence of the formation of a band structure from the shallow mercury 5d eigenstates.