Atomic Displacement Process in Gold

Experimental and theoretical results are presented which bear on the directional dependence of threshold displacement energy $T_d({\theta }^{\prime }, {\phi }^{\prime })$. The major experimental results is that the energy dependence of the electron damage rates measured in thin single crystals oriented along the three low-index directions is nearly the same. With the assumption that $T_d\mathrm{}\left(110\right)\mathrm{}$ and $T_d\mathrm{}\left(100\right)\mathrm{}$ correspond to local minima, the data indicate that $T_d\mathrm{}\left(100\right)\mathrm{}\sim T_d\mathrm{}\left(110\right)\mathrm{}\sim 36$ eV. A corresponding theoretical value of $T_d\mathrm{}\left(100\right)=36\mathrm{}\pm 2$ eV is found when a Born-Mayer-type potential with parameters derived by Andersen and Sigmund is used in computer calculations. Evidence is presented to show that experimentally derived threshold energies may not reflect true $T_d$ values if they correspond to a local maximum in the threshold energy surface, as may be the case in the $〈111〉$ direction.