Direct-excitation cross sections for Cd II low-lying excited states by single-electron impact on Cd atoms

Emission cross sections for ten spectral lines transiting from Cd II low-lying excited states formed by single-electron impact on Cd atoms have been measured with a photon-counting technique. Polarizations of these lines have also been examined. By the use of these results and removing the influence of cascade transitions, direct-excitation cross sections for seven low-lying states ($5p{}_{}{}^2{}_{}{}^{}P_{\frac{1}{2},\frac{3}{2}}^{}{}_{}{}^{}$, $5s^2{}_{}{}^2{}_{}{}^{}D_{\frac{3}{2},\frac{5}{2}}^{}{}_{}{}^{}$, $6s{}_{}{}^2{}_{}{}^{}S_{\frac{1}{2}}^{}{}_{}{}^{}$, $5d{}_{}{}^2{}_{}{}^{}D_{\frac{3}{2},\frac{5}{2}}^{}{}_{}{}^{}$) have been determined as a function of electron energy. They are found to be of the order of ${10}^{-17\mathrm{}}$ ${\mathrm{cm}}^2$ for the $5p$ and $5s^2$ states and of ${10}^{-18\mathrm{}}$ ${\mathrm{cm}}^2$ for the $6s$ and $5d$ states at their maxima.