Line ratios for soft-x-ray emission following charge exchange between O8+ and Kr

Lyman spectra and line ratios are reported for soft-x-ray emissions following the charge exchange process in 293, 414, 586, and 1256 km/s ${\mathrm{O}}^{8+}$ and Kr collisions. Lyman series from Ly-$\ensuremath{\alpha}$ to Ly-$\ensuremath{\varepsilon}$ were resolved for the ${\mathrm{O}}^{7+}$ ion using a high-resolution x-ray quantum microcalorimeter detector. It is found that the observed line ratios are dependent on the $nl$ distribution of the captured electron, and the Ly-$\ensuremath{\alpha}$ and Ly-$\ensuremath{\beta}$ x-ray emissions are enhanced. Moreover, by comparing the measured line ratios to the constructed theoretical single charge exchange line ratios for ${\mathrm{O}}^{8+}+\text{H}$, it is suggested that autoionizing double capture plays a significant role in the enhancement of Ly-$\ensuremath{\alpha}$ and Ly-$\ensuremath{\beta}$ emissions for the present system.