Research on fluorescence spectra and rotational temperature of N2+ induced by femtosecond laser

In this work, the fluorescence spectrum induced by femtosecond laser in pure nitrogen is employed to investigate the characteristics of the rotationally resolved spectrum of nitrogen molecular ions (N2+). In addition, it analyzes the variations in the rotational temperature as a function of propagat...

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Bibliographic Details
Main Authors: Yun Zhang, Canneng Liang, Yu Xia, Yuyao Xiong, Yunfeng Zhang, Fan Liu, Suyu Li, Mingxing Jin
Format: Article
Language:English
Published: AIP Publishing LLC 2025-05-01
Series:AIP Advances
Online Access:http://dx.doi.org/10.1063/5.0257831
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Summary:In this work, the fluorescence spectrum induced by femtosecond laser in pure nitrogen is employed to investigate the characteristics of the rotationally resolved spectrum of nitrogen molecular ions (N2+). In addition, it analyzes the variations in the rotational temperature as a function of propagation distance under different pressures. The overall trend in the rotational temperature of N2+ with the propagation distance is similar to that of the fluorescence emission intensity. Experiments demonstrate that the change in pressure affects the dynamics of femtosecond filamentation, thereby influencing the energy distribution along the propagation direction and resulting in differences in the fluorescence signal intensity distribution. Compared to the pressure of 10 000 Pa, the overall rotational temperature of N2+ at 200 Pa is relatively lower, which is attributed to the variation in the collision probability between particles caused by the pressure change. This study clarifies the intrinsic relationship between the fluorescence spectrum and the rotational temperature of N2+, providing a theoretical and experimental foundation for understanding the physical mechanism of femtosecond laser-induced fluorescence spectra.
ISSN:2158-3226