Heavy ion excitation of solid rare gases

The vacuum ultraviolet (VUV) emission of solid Ar, Kr, and Xe targets excited by heavy ion beams was studied in order to explore the possibility of VUV laser action. A pulsed 75 MeV 32S beam with 14.4 μJ pulse energy and 2 ns pulse width was used. Wavelength spectra measured during 10 and 90 ns time windows after the beam pulse showed strong VUV emission from the decay of the quasi-molecular 1Σ+u and 3Σ+u self-trapped excitons. The decay times of these states were measured for all three rare-gas targets. Cross sections for stimulated emission of 5.7×10−18, 1.3×10−17, and 2.4×10−17 cm2 in Ar, Kr, and Xe, respectively, were deduced from the linewidth and lifetime of the 1Σ+u to ground-state transition. A 1Σ+u state population density of 9.6×1013 cm−3 was determined in solid Xe from an absolute intensity measurement.