X-Ray Emission From Electron Capture By Highly-Charged Ions

Recently, electron capture by highly-charged ions has been recognized as the major source of X-ray emission from comets. It has been proposed that highly-charged ions of minor solar wind species such as C, N, O, and Ne emit X-rays following electron capture from cometary atoms and molecules such as H, CO, OH, H2O, and CO2, In our work we have measured accurate cross sections for single and multiple electron capture by solar wind ions in collision with various gas targets. We have also observed X-ray Lyman transitions from Hand He-like ions formed in the capture process. The importance of multiple transfer, autoionization and the l-distribution of initial capture states will be discussed in light of our results.