Towards XUV lasers with charge transfer pumping

Detailed studies of charge exchange pumping of ions in femtosecond laser-produced plasmas colliding with a pulsed gas jet are presented. Strong selective excitation of XUV ionic transitions in the reaction C4+ + H → C3+ + H+ is observed. Dependences of line intensities on various experimental parameters are reported which are in good agreement with the theory of charge transfer processes. Analyses of experimental data provide evidence that an efficient charge exchange pumping is realized at densities of reagents well in excess of 1016 cm−3, which is essential for the realization of XUV lasers. In preliminary investigations of the reaction C6+ + H → C5+ (n = 3, 4) + H+ a strong increase of line intensities at 13.5 and 18.2 nm is reported. Analysis of lasing in Na-like ions with an example for Chlorine promises even more efficient pumping as compared with the before analyzed hydrogen like ions.