Amplification of laser radiation at the edge of the KrF (B – X) spectral line

We report the results of experimental and numerical studies of the KrF electric discharge amplifier operating on a mixture of He – Kr – F₂ gases. The possibility of expanding the short-wavelength spectral region of the induced radiation tuning at the B – X transition of the KrF molecule by removing the inverse population from the upper vibrational states of the electronic B level is shown. It is demonstrated that at the boundary of the active medium gain contour, the measured gain at a wavelength of 246.8 nm is 0.053 cm^-1. Using the developed 1D model of the KrF electric discharge amplifier, it is shown that when the active medium is excited by a pump pulse with a specific peak power of ~10 MW cm^-3, the gain in this spectral region is due to a longer relaxation time of the population of excimer molecules from the upper vibrational levels compared with the characteristic time of their production.