Experimental investigation of the processes determining x-ray emission intensities from charge-exchange collisions - art. no. 062707

Absolute cross sections have been measured for single and double charge exc hange and x-ray line emission for highly charged ions of C, N, 0, and Ne co lliding with He, H-2 CO2, and H2O at collisions energies of 7q keV. Present results of charge exchange in He and H-2 compare favorably with previous r esults. For CO2 and H2O, where prior work is scarce, the classical overbarr ier model is found to overestimate results by up to a factor of 3. An analy sis of the relative intensities of the observed Lyman x-ray transitions ind icates that capture into l states is not statistical, as collision velociti es are insufficient to populate the highest angular-momentum states. The im portance of autoionization following multiple capture is highlighted, and e nhanced radiative stabilization following double capture is observed and co mpared to other studies. Present results are also discussed in terms of mec hanisms likely to generate x-ray emission in comets.