Stimulated emission due to infrared transitions in chlorine atoms in gaseous mixtures pumped by uranium fission fragments

Quasi-cw stimulated emission of ~10 ms pulses at the wavelengths λ =1.59 and 2.45 μm of the chlorine atom was detected when mixtures of He, Ne, and Ar with CCl₄, CHCl₃, CF₂Cl₂, and C₂F₃Cl₃ were excited by uranium fission fragments. Stimulated emission of the λ = 2.45 μm line under nuclear pumping conditions at high pressures was observed for the first time. The maximum energy parameters (output radiation power 130 W, efficiency about 0.2%) were achieved for the 1.59 μm line in a mixture of the He : Ne : CCl₄ = 25 000 : 25 000 : 1 composition at a pressure of 2 bar. The minimum lasing threshold for this line corresponded to a thermal neutron flux of 2×10¹³ cm^-2 s^-1.