Electron-impact excitation of the (5s²5p) ²P½ → (5s²6s) ²S½ transition in indium: theory and experiment

We present angle-integrated and angle-differential cross sections for electron-impact excitation of the (5s²5p) ²P½ → (5s²6s) ²S½ transition in atomic indium. Experimental data for six incident electron energies between 10 and 100 eV are compared with predictions from semirelativistic and fully relativistic B-spline R-matrix calculations, as well as a fully relativistic convergent close-coupling model. Agreement between our measured and calculated data is, with a few exceptions, found to be typically very good. Additionally, the agreement between the present theoretical predictions is generally excellent, with the remaining small deviations being associated with the slightly different, although still very accurate, descriptions of the target structure. Agreement between the present results and an earlier relativistic distorted-wave computation [T. Das, R. Srivastava, and A. D. Stauffer, Phys. Lett. A 375, 568 (2011)] was, however, found to be marginal, particularly at 10 and 20 eV