Merged-Beams Measurements of Absolute Cross Sections for Electron-Impact Excitation of S4+ (3s2 1S → 3s3p 1P) and S5+(3s 2S → 3p 2P)

Abstract

Absolute cross sections for electron-impact excitation of the dipole-allowed transitions S⁴⁺ (3s^{2 1}S → 3s3p ¹P)and S⁵⁺(3s ²S → 3p ²P) were measured near threshold using the merged electron-ion beams energy-loss (MEIBEL) technique. Although the magnitude of the measured cross sections are in reasonable agreement with available theoretical data, the experimental data indicate that the contributions of dielectronic resonances in the near-threshold region are underestimated by these calculations.