Unexpected coexistence of radiation and absorption in rotationally excited nitrogen molecular ions. Issue 8 (4th May 2021)

• Record Type: Journal Article
• Authors: Su, Rongbo; Wang, Fujun; Dan, Guiping; Kang, Wu; Tan, Zhaoyi; Ding, Jingjie
• Is Part Of: Journal of modern optics. Volume 68:Issue 8(2021)
• Page Start: 433
• Page End: 439
• Publication Date: 2021-05-04
• Subjects: Femtosecond filamentation -- lasing effect -- nitrogen molecularion; Optics -- Periodicals; 535
• DOI: 10.1080/09500340.2021.1909157
• Languages: English
• ISSNs: 0950-0340

Abstract

ABSTRACT: We studied the dynamic evolution of the rotational states by measuring the laserlike narrow-bandwidth coherent radiation of N 2 + from N 2 + ( B 2 Σ u + ) to N 2 + ( X 2 Σ g + ) . The coexistence of radiation and absorption was observed when the ratio of population in the N 2 + ( B 2 Σ u + ) and N 2 + ( X 2 Σ g + ) states is around unity. The absorption turns up on the blue side of the radiation with a time delay of 250 fs. Based on a semiclassical radiation and absorption model, it was found that the fast rotational temperature evolution, determining the population distribution on the rotational states, holds the key to understand this behaviour.