Electron capture to ${\mathrm{D}}_3^{-}$ and ${\mathrm{D}}_3^0$ repulsive states by ${\mathrm{D}}_3^{+}$ in Cs

Differential cross sections for the production of ${\mathrm{D}}^{-}$ and ${\mathrm{D}}^0$ + ${\mathrm{D}}_2^0$ + ${\mathrm{D}}_3^0$ are given for electron-capture collisions into ${\mathrm{D}}_3^{-}$ and ${\mathrm{D}}_3^0$ repulsive states by bombardment of Cs with ${\mathrm{D}}_3^{+}$ ions in the energy range 1.5-7.5 keV. A theory is presented for the angular distributions of dissociation fragments in the special cases in which the dissociation (i) produces two fragments, or (ii) produces three fragments, one of which has a small energy in the molecular center-of-mass frame. In both cases a scaling law is predicted: ${\left({\gamma }_n{E}_i\right)}^{-1\mathrm{}}$ $\frac{d{\sigma }_n}{d\omega }=f\left({\gamma }_n{E}_i{\theta }_n^2\right)$, where $\frac{d{\sigma }_n}{d\omega }$ is the differential cross section for finding fragment $n$ at angle ${\theta }_n$, $E_i$ is the incident energy, and ${\gamma }_n$ is a mass ratio. The ${\mathrm{D}}^{-}$ distributions are observed to fit this scaling law. Peaks are found in both the ${\mathrm{D}}^{-}$ and ${\mathrm{D}}^0$ + ${\mathrm{D}}_2^0$ + ${\mathrm{D}}_3^0$ distributions for which $\frac{1}{2}{E}_i{\theta }^2\simeq 15$ keV ${\mathrm{deg}}^2$ and 14 keV ${\mathrm{deg}}^2$, respectively. A corresponding peak is also found in the neutral distribution for which $2E_i{\theta }^2\simeq 14$ keV ${\mathrm{deg}}^2$. The peaks indicate a repulsive state in ${\mathrm{D}}_3^{-}$ which decays into