标题： C$_3$的弯曲：实验探测$l$型双态和共振 显示英文标题

标题： The Bending of C$_3$: Experimentally Probing the $l$-type Doubling and Resonance

摘要： C$_3$是一种纯碳链分子，在不同的天文学环境中已被识别，被认为是通过观察其基态中涉及低能弯曲模 ($\nu_2$) 的跃迁来探测动能温度的良好探针。目前的实验室工作旨在通过结合放电实验中产生的 C$_3$的高分辨率光学和红外光谱记录，研究该弯曲模的多量子激发。通过使用单纵模光学参量振荡器作为窄带宽激光源，中国科学技术大学记录了罗维布里尼克 (A$^1\Pi_u -$ X$^1\Sigma_g^+$) 跃迁的光学光谱。从 X(0$v_2$0),$v_2 = 0-5$中归属了36条带。 中红外光谱的转动振动$\nu_3$带已通过傅里叶变换红外光谱法在SOLEIL同步辐射设施的AILES光束线上使用globar光源记录。该光谱揭示了涉及最多5个激发量子的热带，在$\nu_2$中。通过结合目前记录的所有光谱和文献数据，准确的旋转参数和C$_3$的绝对能级被确定，特别是涉及弯曲模式的状态。一个包含所有涉及X和A态的数据（文献和本研究）的PGOPHER文件用于拟合所有数据。从本工作获得的光谱信息使得对C$_3$的新的星际搜索成为可能，不仅在此处研究的红外和光学区域，而且特别是在$\nu_2$带区域（约63厘米$^{-1}$）中，现在可以准确预测振动卫星。这使得C$_3$成为研究非常不同的天体环境的通用诊断工具，从黑暗致密云到半透明云。 显示英文摘要

摘要： C$_3$, a pure carbon chain molecule that has been identified in different astronomical environments, is considered a good probe of kinetic temperatures through observation of transitions involving its low-lying bending mode ($\nu_2$) in its ground electronic state. The present laboratory work aims to investigate this bending mode with multiple quanta of excitation by combining recordings of high resolution optical and infrared spectra of C$_3$ produced in discharge experiments. The optical spectra of rovibronic (A $^1\Pi_u -$ X $^1\Sigma_g^+$) transitions have been recorded by laser induced fluorescence spectroscopy using a single longitude mode optical parametric oscillator as narrow bandwidth laser source at the University of Science and Technology of China. 36 bands originating from X(0$v_2$0), $v_2 = 0-5$, are assigned. The mid-infrared spectrum of the rovibrational $\nu_3$ band has been recorded by Fourier-transform infrared spectroscopy using a globar source on the AILES beamline of the SOLEIL synchrotron facility. The spectrum reveals hot bands involving up to 5 quanta of excitation in $\nu_2$. From combining analyses of all the presently recorded spectra and literature data, accurate rotational parameters and absolute energy levels of C$_3$, in particular for states involving the bending mode, are determined. A single PGOPHER file containing all available data involving the X and A states (literature and present study) is used to fit all the data. The spectroscopic information derived from this work enables new interstellar searches for C$_3$, not only in the infrared and optical regions investigated here but also notably in the $\nu_2$ band region (around 63 cm$^{-1}$) where vibrational satellites can now be accurately predicted. This makes C$_3$ a universal diagnostic tool to study very different astronomical environments, from dark and dense to translucent clouds.