Detection of transient species by using Cavity Ringdown spectrometer combined with a new type slit nozzle

东京大学和鹿儿岛大学建造了与放电喷嘴相结合的腔衰荡（CRD）光谱仪。由于CRD光谱仪受反射镜反射率的影响较大，鹿儿岛的仪器安装在洁净室中，以防止火山灰进入，新仪器安装了新型狭缝喷嘴，以防止样品气体发散到光轴外。利用MRCI对HO_3自由基进行了高水平的从头算计算。所得的HO_3分子势能面与实验结果吻合较好。由势能面求得HO_3自由基的振转耦合常数，确定了HO_3自由基的平衡结构。

The Cavity Ringdown(CRD) spectrometer combined with the discharged nozzle was constructed in the University of Tokyo and Kagoshima University. Because CRD spectrometer is severely affected by reflectivity of mirror, the apparatus in Kagoshima was installed in clean room to keep out the ash from the volcano.New type slit nozzle was installed in new spectrometer to prevent the sample gas from diverging outside the optical axis. High-level ab initio calculation of the HO_3 radical was performed by using MRCI. The obtained potential energy surface of HO_3 reproduces experimental results well. The equilibrium structure of the HO_3 radical was determined by using the vibration-rotation coupling constants, which was obtained from the potential energy surface.