EUV spectra of Xe xvii-Xe xxi produced in charge-exchange collisions

Charge-state-specific spectra produced from charge exchange collisions between xenon ions and helium target atoms using an ECR (electron cyclotron resonance) source have been recorded in extreme ultraviolet (EUV). At low target gas pressures, the spectra were produced after a single collision event involving electron capture by the projectile ion and in each case intense emission near 11 nm was observed. The spectra of Xe16 ⁺ to Xe20 ⁺ are compared with atomic structure calculations and the possible mechanisms for electron capture are discussed. There is some evidence that for lower charged ions the spectra in the 10-15 nm region result mainly from transfer excitation or ionization processes rather than direct single electron capture into high nl states.