Anomalous broadening and shift of emission lines in a femtosecond laser plasma filament in air


Ильин А. А., Голик С.С., Шмирко К.А., Майор А.Ю., Прощенко Д.Ю.

Статьи в журналах

Spectrochimica Acta Part B Atomic Spectroscopy

Нидерланды, Амстердам, Elsevier

Spectrochimica Acta Part B Atomic Spectroscopy, Vol. 138, p. 97-105




The temporal evolution of the width and shift of N I 746.8 and O I 777.4 nm lines is investigated in a filament plasma produced by a tightly focused femtosecond laser pulse (0.9 mJ, 48 fs). The nitrogen line shift and width are determined by the joint action of electron impact shift and the far-off resonance AC Stark effect. The intensive (I = 1.2·1010 W/cm2) electric field of ASE (amplified spontaneous emission) and post-pulses result in a possible LS coupling break for the O I 3p 5P level and the generation of Rabi sidebands. The blueshifted main femtosecond pulse and Rabi sideband cause the stimulated emission of the N2 1+ system. The maximal widths of emission lines are approximately 6.7 times larger than the calculated Stark widths.