Stimulated emission of the 535 nm thallium line as a result of quasiresonant optical pumping of a Tl–He mixture by radiation from a recombination He–Ca laser

Stimulated emission of the 535 nm line of thallium was observed when a Tl-He mixture was pumped optically in the violet wing of a pressure-broadened resonance line of thallium at 377.6 nm by a recombination He–Ca laser emitting at λ = 373.7 nm. Pumping resulted from the absorption transitions between repulsive terms of the Tl-He quasimolecule. The average stimulated radiation power reached 5 mW when the pulse repetition frequency was 6 kHz. The efficiency of conversion of the useful part of the pump pulse was 45%.