Observation of soft x-ray amplification in neonlike molybdenum

Thin molybdenum coated foils have been irradiated in line focus geometry with from 3 to 8×1014 W cm−2 of 0.53-μm light at the Nova laser. The resulting exploding foil plasma has demonstrated x-ray laser gain at four wavelengths (106.4, 131.0, 132.7, and 139.4 Å), identified as 3s-3p transitions in neonlike Mo. The J=0–1, a 3s–3p transition at 141.6 Å has been identified, but does not show evidence of significant gain in disagreement with the theory.