Femtosecond-pulse-driven 10-Hz 41.8-nm laser in Xe IX

We report the observation of extreme UV lasing at 41.81 nm on the 4c(9)5d S-1(0)-4d(9)5(p) P-1(1) transition in Xe IX, as proposed by Lemoff et al. [Opt. Lett. 19, 569 (1994)]. A 10-Hz circularly polarized 800-nm laser pulse with an energy of similar to 70 mJ and a duration of similar to 40 fs is longitudinally focused to a peak intensity of > 3 x 10(16) W/cm(2) over a length of 8.4 nm in a differentially pumped cell containing 12 Torr of Xe gas. observed with an estimated gain coefficient of 13 cm(-1) and a total gain of exp(11). (C) 1996 Optical Society of America