We report the first observation of amplification of spontaneous emission at soft x-ray wavelengths by ions in the nickel-like sequence. The ions are created by high-intensity laser irradiation of a thin foil. Gains of order 1 cm-1 are observed on J=0-1, 4d-4p transitions in Eu35+ at 65.83 and 71.00 AI. There is some evidence for amplification on the analogous lines at 50.26 and 56.09 AI in Yb42+. The pumping mechanism is believed to be electron collisional excitation from the ground state. The scheme should be readily scalable to produce amplification in W46+ at 43.15 AI.
ASJC Scopus subject areas
- Physics and Astronomy(all)