Absorption and emission characteristics of femtosecond laser plasma filaments in the air


2015

Ильин А. А.

Статьи в журналах

Spectrochimica Acta Part B Atomic Spectroscopy

Elsevier

Vol. 112

16-22

3.18

ISSN: 0584-8547

Alexey A. Ilyin, Sergey S. Golik, Konstantin A. Shmirko, Absorption and emission characteristics of femtosecond laser plasma filaments in the air // Spectrochimica Acta Part B Atomic Spectroscopy Vol. 112, p.16-22, 2015 DOI: 10.1016/j.sab.2015.08.002

The digital images of plasmas induced by tightly focused Ti:Sapphire laser (1.1 mJ, 48 fs) in air reveal new fluorescent structures not observed for slightly focused beams earlier. The fluorescent structures arise because of lens aberrations. The energy absorbed by femtosecond laser plasma has nonlinear dependence on incident laser energy. The threshold peak power for filament formation is 5.2 GW. Time-resolved spectroscopy of plasmas shows short-time emission of molecular bands (up to 1 ns) and long-time emission of atomic lines (up to 150 ns). Initially, second positive system of N2 and first negative system of N2+ are observed. The atomic lines are formed with delay of 50-80 ps relative to molecular ones. Lines of N2 and N2+ demonstrate different temporal behavior, while lines of N I and O I have the same intensity time dependence. Peak intensities of second positive system of N2 and first negative system of N2+ are separated by 50 ps time interval.