Vol. 29, issue 02, article # 7

Abstract:

The experimental results of the study of population inversion in the resonant electronic transition B³П_g-A³∑_u⁺ of nitrogen ions by optical pump of air and pure nitrogen by a femtosecond laser pulse at a wavelength of 950 nm are presented. It is shown that the inversion results from selective settling of N₂⁺ (B²∑_u⁺,ν´=0) excited state during multiphoton excitation of the autoionization state of the nitrogen molecule with energy of 18.7 eV. Seed photons for superradiance at transitions of molecular nitrogen ions are photons of the axial supercontinuum occurring in a filament at the corresponding wavelengths. The mode of the superradiance at the wavelength λ = 358.4 nm, referred to the transition of the CN molecules, was implemented.

Keywords:

filament, population inversion, femtosecond laser pulse, multiphoton ionization, molecule, ions

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