Test of predictedΔn≥1L-shell dielectronic-recombination cross sections

The predicted charge-state dependence of dielectronic-recombination cross sections involving {Δ}n>=1 L-shell excitation has been tested by measurements of resonant transfer and excitation (RTE) for ₄₁Nbq++H₂ (q=28 to 32) collisions at 3.7 and 4.0 MeV/u. The measured RTE cross sections increase significantly with increasing charge state and thus disagree substantially with theoretical calculations that predict essentially equal cross sections for Nb²⁹⁺, Nb³⁰⁺, and Nb³¹⁺. This disagreement is contrary to the good agreement previously found between theory and experiment for K-shell RTE.