Mechanism of population inversion in laser-driven N2+. (5th February 2019)

• Record Type: Journal Article
• Authors: Zhang, Youyuan; Lötstedt, Erik; Yamanouchi, Kaoru
• Is Part Of: Journal of physics. Volume 52:Number 5(2019:Mar. 01)
• Publication Date: 2019-02-05
• Subjects: Floquet -- strong fields -- air-lasing -- population inversion; Atoms -- Periodicals; Molecules -- Periodicals; Optics -- Periodicals; Nuclear physics -- Periodicals; 539.6
• DOI: 10.1088/1361-6455/aafbdc
• Languages: English
• ISSNs: 0953-4075

Abstract

Abstract: On the basis of our theoretical model of the population transfer between two levels interacting suddenly with an intense laser pulse (Zhang et al 2017 J. Phys. B: At. Mol. Opt. Phys. 50 185603), we investigate the mechanism of the population inversion between the electronically excited B 2 Σ u + state and the electronic ground X 2 Σ g + state of N2 + achieved by the irradiation of a near-IR (800 nm) intense laser pulse, leading to the generation of the coherent emission at 391 nm. We show that one of the Floquet states generated at the moment when N2 + starts interacting with an intense laser pulse is adiabatically connected to the ground vibrational state of the electronic B 2 Σ u + state and keeps a constant population throughout the period of the interaction with the light field, indicating that the efficient off-resonance B 2 Σ u + – X 2 Σ g + transition proceeds.