Electron-impact excitation of the (3d104s)2S1/2→(3d94s2)2D5/2,3/2 transitions in copper atoms

Results from a joint experimental and theoretical investigation of electron impact excitation of the (3d104s)2S1/2→(3d94s2)2D5/2,3/2 transitions in copper atoms are presented. The experimental results were obtained with the laser-induced fluorescence technique, while the numerical calculations were performed in a variety of nonrelativistic, semirelativistic, and fully relativistic R-matrix (close-coupling) calculations. Whereas there is qualitative agreement between the measured and predicted energy dependence of the angle-integrated cross section, significant uncertainties remain regarding the position and the height of the near-threshold maximum of the excitation function for the (3d94s2)2D3/2 state. These uncertainties translate into difficulties regarding the absolute normalization of the relative experimental data to the theoretical predictions.