Energy Distribution of Slow Positrons Diffusing from Incomplete<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>d</mml:mi></mml:math>-Shell Transition Metals

Abstract

The energy distribution of slow positrons diffusing from chemically cleaned and partially outgassed polycrystalline tungsten, molybdenum, and chromium is made up of two principal parts, a broad asymmetric peak at 0.2 \ifmmode\pm\else\textpm\fi{} 0.1 eV with a width of ~ 2 eV, and a second sharp, usually symmetric, peak with an energy which depends upon the material under study. The second peak is believed to be associated with the bulk properties of the material, in particular, with the electronic density of states.