Fluorescence emission from excited molecular ions in intense femtosecond laser fields

The fast decay of ionized nitrogen molecules in laser filamentation investigated by a picosecond streak camera

“…and N 2 (C 3 Π u , v′=0→B 3 Π g , v=0) [27,31]. By fitting the falling edge of the 391 nm fluorescence curve with an exponential decay function, the time corresponding to the fast decay is determined to be ∼200 ps and more than two orders of magnitude shorter than its spontaneous lifetime.…”

“…Under our experimental condition, the possible collisional partners are nitrogen molecules, ions and free electrons. In the case of nitrogen molecules, the collision time between + N 2 (B) and N 2 is on the time scale of ten nanoseconds in the pressure of several mbar according to our previous studies [27][28][29]. Both the collision of nitrogen molecules as well as the spontaneous emission leads…”

“…is as long as 60 ns [27], the first possible scenario of the fast decay is caused by the cooperative spontaneous emission for an ensemble of coherently excited molecules (e.g. superradiance).…”

“…due to the collision with nitrogen molecules as well as spontaneous emission, which have been studied in our previous reports [27][28][29]. In the following, we focus on exploring the mechanism for the fast decay of…”

“…Time-resolved fluorescent emission contains the information of population evolution in the upper state of the transition and sheds new light on extending the duration of the optical gain. In our previous papers [27][28][29], we detect the fluorescence emission of…”