Charge-transfer pumping for XUV lasers

Abstract

The interaction of a femtosecond laser-produced ablation plasmawith a pulsed gas jet is studied. XUV spectroscopic investigationsshow that charge-exchange excitation due to the reaction C4+ + H → C3+ (n = 3) + H+ takesplace in the interaction region. The dependence of line intensities on different experimentalparameters is studied. At optimum conditions, the 3p–2s transition of C3+ions at 31.2 nm wavelength shows an increase of up to four times in the lineintensity which is induced by the gas jet at a backing pressure of 100 mbar ata distance of 1 mm from the target surface, while transitions from then = 4and higher levels decrease. Preliminary experiments with an Al2O3target show even a tenfold increase in intensity of the 2p3s–2p2 line (λ = 37.4 nm) ofO2+ions.