Angular distributions of dissociation fragments from low-kilovolt-energy collisions ofH2+on He

Differential cross sections are presented for the production of ${\mathrm{H}}^{+}$ and ${\mathrm{H}}^0$ fragments produced in collisions of ${\mathrm{H}}_2^{+}$ with He at collision energies 0.5, 1.0, 2.0, and 3.0 keV. The results are interpreted in terms of direct collisional excitation of the $1\sigma u$ repulsive state of ${\mathrm{H}}_2^{+}$ and charge exchange into the ${}_{}{}^3{}_{}{}^{}\Sigma _u^{}{}_{}{}^{}$ repulsive state of ${\mathrm{H}}_2^0$. The angular distributions of ${\mathrm{H}}^0$ fragments which arise from the ${\mathrm{H}}_2^0$ repulsive state are given by the angular distribution for (½)$({\mathrm{H}}^0-{\mathrm{H}}^{+})$. The results are in agreement with those of previous experiments and extend the earlier work down to lower collision energies. The measured angular distributions fit a scaling law $\left(\frac{1}{E_{\mathrm{inc}}}\right)\frac{d\sigma }{d\omega }=N\left(E_{\mathrm{inc}}\right)f_i\left(E_{\mathrm{inc}}{\theta }^2\right)$, where $i$ indicates the dissociation fragment.