ELECTRON-IMPACT IONIZATION OF IN+ AND XE+

Absolute ionization cross sections for In+ and Xe+ by electron impact have been measured from below threshold to 200 eV using the crossed-beams technique. The cross sections for In+ were possibly enhanced by indirect ionization processes. The excitation of the ion from the 4d(10)5s2 ground state to the 4d(9)5s(2)5p state followed by autoionization has been postulated. The In+ cross sections show a peak value of 15.9 X 10(-17) cm2 at about 80 eV. The cross sections for Xe+ peak at a value of 25. 6 X 10(-17) cm2 at about 35 eV. Experimental measurements are compared to configuration-averaged distorted-wave calculations [M. S. Pindzola et al., J. Phys. B 16, L355 (1983)], the semiempirical formula of Lotz [Z. Phys. 216, 241 (1968)], and, in the case of Xe+, previous experimental results [C. Achenbach et al., J. Phys. B 17, 1405 (1984)]. Also presented are ionization-rate coefficients and fitting parameters for both ions for temperatures in the range 10(4) K less-than-or-equal-to T less-than-or-equal-to 10(7) K.