Mass Spectrometric Investigation of Surface Ionization. VI. Desorption of Th+, Np+, and Pu+ from Tungsten Surfaces

Abstract

The mean residence times of Th⁺, Np⁺, and Pu⁺ on polycrystalline tungsten surfaces have been determined as functions of temperature using the modulated beam technique. The desorption parameters, determined from the relationship ${\text{1\hspace{0.17em}/\hspace{0.17em}τ\hspace{0.17em}=\hspace{0.17em}ω}}_0\exp {\mathrm{(-\hspace{0.17em}E}}_i\mathrm{\hspace{0.17em}/\hspace{0.17em}kT)}$ , are $$\begin{array}{ccc}\mathrm{Ion}& {\omega }_0({\sec }^{\text{−1}})& E_i(\mathrm{eV})\\ {\mathrm{Th}}^{+}& {\text{(1.7\hspace{0.17em}±\hspace{0.17em}1.5)\hspace{0.17em}×\hspace{0.17em}10}}^{14}& \text{7.83\hspace{0.17em}±\hspace{0.17em}0.25}\\ {\mathrm{Np}}^{+}& {\text{(6.8\hspace{0.17em}±\hspace{0.17em}3.8)\hspace{0.17em}×\hspace{0.17em}10}}^{13}& \text{6.32\hspace{0.17em}±\hspace{0.17em}0.12}\\ {\mathrm{Pu}}^{+}& {\text{(1.6\hspace{0.17em}±\hspace{0.17em}0.9)\hspace{0.17em}×\hspace{0.17em}10}}^{12}& \text{4.99\hspace{0.17em}±\hspace{0.17em}0.15.}\end{array}$$