Excitation cross sections ofCd+ions for the upper and lower states of the Cd II 441.6-nm laser line by electron impact

The excitation cross sections by electron impact from the Cd II ground state to the laser upper state $5s^2{}_{}{}^2{}_{}{}^{}D_{\frac{5}{2}}^{}{}_{}{}^{}$ (Beutler state) and the laser lower state $5p{}_{}{}^2{}_{}{}^{}P_{\frac{3}{2}}^{}{}_{}{}^{}$ (resonance state) have been measured by using a crossed-beam method of electrons and ${\mathrm{Cd}}^{+}$ ions and a photoncounting method. The electron-energy region investigated was from the threshold energy (5.8 eV) for the excitation of the $5p{}_{}{}^2{}_{}{}^{}P_{\frac{3}{2}}^{}{}_{}{}^{}$ state to 20 eV. It has been shown that the excitation cross section for the ionic Beutler state $5s^2{}_{}{}^2{}_{}{}^{}D_{\frac{5}{2}}^{}{}_{}{}^{}$ is of the order of ${10}^{-15\mathrm{}}$ ${\mathrm{cm}}^2$ and has a sharp peak near the threshold energy for the excitation. The excitation cross section for the resonance state $5p{}_{}{}^2{}_{}{}^{}P_{\frac{3}{2}}^{}{}_{}{}^{}$ has also been of the order of ${10}^{-15\mathrm{}}$ ${\mathrm{cm}}^2$ and has a relatively broad maximum.