Fine-Structure Transitions in Ar+(2Pj)+Ar(1S0) Collisions in the Energy Range 60 eV–1500 eV

Direct fine-structure transitions, j=3/2 →1/2 and j=1/2 →3/2, were first observed with an ion energy-loss spectrometer at near 0°. The ions were produced with an electron-impact ion source. The peak heights corresponding to both transitions were almost the same over the energy range studied. The ratio of the 3/2 to 1/2 states in the primary ions was determined to be in statistical ratio, 2:1, assuming detailed balance for the transitions. Partial excitation cross-sections for the forward scattering within the angle ±0.45° were evaluated from the spectra obtained.