AMPLIFICATION IN NI-LIKE NB AT 204.2-ANGSTROM PUMPED BY A TABLE-TOP LASER

We identified for the first time the 3d(9)4dS1 -3d(9)4p1P line in Ni-l ike Nb at 204.2 angstrom that was predicted to show gain. When pumped with a train of pulses containing less than 1 J per pulse, significant emission was recorded at 204.2 angstrom following the second and the third pulses. We measured the small signal gain coefficient per Joule of incident laser energy to be 1.49+/-0.42 cm-1 J-1 for this laser tra nsition, which is higher by several orders of magnitude than that repo rted for other collisional laser systems in this wavelength range.