ABSOLUTE CROSS-SECTIONS FOR NEAR-THRESHOLD ELECTRON-IMPACT EXCITATIONOF THE 2S S-2-]2P P-2 TRANSITION IN C3+

Absolute total cross sections for electron-impact excitation of the 2s S-2-->2p P-2 transition in C3+ were measured from 7.35 eV to 8.35 eV using the merged electron-ion-beams energy-loss technique. The results settle the discrepancy between two previous experiments using the cro ssed-beams fluorescence method, being in very good agreement with the older results [P. O. Taylor, D. Gregory, G. H. Dunn, R. A. Phaneuf, an d D. H. Crandall, Phys. Rev. Lett. 39, 1256 (1977)] but less so with t he more recent ones [D. W. Savin, L, D. Gardner, D. B. Reisenfeld, A. R. Young, and J. L. Kohl, Phys. Rev. A 51, 2162 (1995)]. The present m easurements are also in good agreement with unitarized Coulomb-Born an d close-coupling calculations. [S1050-2947(98)04301-7].