Localized-plasma-assisted rotational transitions in the terahertz region
Yindong Huang, Zuoxian Xiang, Xing Xu, Jing Zhao, Jinlei Liu, Ruixing Wang, Ziyi Zhang, Zhihui Lü, Dongwen Zhang, Chao Chang, Jianmin Yuan, Zengxiu Zhao
Abstract
Molecular spectroscopy is a powerful tool for accelerating advances in materials science, chemistry, biology, and astronomy. Typically, molecular spectroscopy uses nanotips or nanoparticles to locally detect the molecule properties in a sample resulting from absorption of infrared and terahertz radiations. Here, we present an alternative that transient localized plasma can be applied to enhance the molecular spectroscopy. Our experiments show a significant enhancement of rotational transitions in carbon monoxide plasma under the illumination of terahertz waves. We proposed a semiclassical model for this enhancement, dominated by the energy exchange from electrons to molecules or ions via a collision process in the localized plasma. Our findings gain more insight into the nonequilibrium dynamics in laser-generated localized plasma. We also propose that the localized plasma can be used to improve the sensitivity of molecular spectroscopy.