Quasi-continuous operation of an IF(B–X) laser involving levels populated as a result of VT relaxation

Quasi-cw operation of an IF(B–X) laser was achieved as a result of filling of levels by VT relaxation. The duration of emission from the IF laser was governed by the duration of the pump pulses and it amounted to 25 μs. The output energy was 3 mJ and the quantum efficiency was 15% relative to the absorbed pump radiation. An estimate was obtained of the VT relaxation rate constant of the ground state of the IF(X) molecule interacting with helium: k_VT ≈ 10^– 13 cm³/s.