Absolute cross sections for near-threshold electron-impact excitation of the 2s S 2p P transition in C

Absolute total cross sections for electron-impact excitation of the 2s S 2p P transition in C were measured from 7.35 eV to 8.45 eV using the merged electronion beams energy-loss technique. The results settle the discrepancy between two previous experiments using the crossed-beams fluorescence method, being in very good agreement with the older results [P. O. Taylor, D. Gregory, G. H. Dunn, R. A. Phaneuf, and D. H. Crandall, Phys. Rev. Lett. 39, 1256 (1977)] but less so with the more recent ones [D. W. Savin, L. D. Gardner, D. B. Reisenfeld, A. R. Young, and J. Permanent address: Department of Physics, Chungnam National University, Gung-Dong 220, 305-764, Daejon, South Korea. Permanent address: Department of Physics, St. Francis Xavier University, Antigonish, Nova Scotia, Canada B2G 2W5.