EFFECT OF SPIN-ORBIT STATES OF KR-ELECTRON CAPTURE SPECTRA OF C2+ IONS( AND XE+ ON THE SINGLE)

High resolution translational energy spectra have been obtained for st ate-selective single-electron capture by 8 keV C2+ in Ar and 6 keV C2 in Kr and Xe. The Ar spectrum displays 12 well-resolved peaks which f all into two sequences corresponding to capture from the ground S-1 st ate and the metastable P-3(0) State of the C2+ ion. The only two captu re channels which violate spin conservation in this range of energy ga in are notably absent from this spectrum. The effect of spin-orbit spl itting (0.18 eV) of the P-2(3/2,1/2) ground state of the Ar+ ion is no t apparent in this spectrum. By contrast the spin-orbit splitting of t he P-2(3/2,1/2) states of the Kr+ (at 0.67 eV) and Xe+ (at 1.31 eV) io ns is strongly reflected in the respective spectra. The Kr+ spectrum r eveals six pairs of neatly arranged doublet peaks, while the Xe+ spect rum displays a less obvious relationship between the doublets.