Femtosecond laser-induced nitrogen fluorescence emission at different air pressures

Abstract

In this paper, we experimentally investigate femtosecond laser-induced nitrogen fluorescence emission at different air pressures (0.1\u2009Pa–100\u2009kPa). The variation of nitrogen molecule ( N 2) and molecular nitrogen ion ( N 2 +) characteristic fluorescence spectral lines intensity as a function of air pressure is observed. When the air pressure is between 10\u2009Pa and 100\u2009kPa, the intensity of fluorescence signals from N 2 + and N 2 shows opposite variation as a function of air pressure. We deduce that dissociative recombination is the main pathway for the production of the C 3 ∏ u state of N 2. This research helps elucidate the physical emission mechanism of femtosecond laser-induced nitrogen fluorescence emission.