High-resolution electronic spectra of yttrium oxide(YO)Ⅰ:identification of the D2Σ+ state
作者单位：Hefei National Laboratory for Physical Sciences at the MicroscaleDepartment of Chemical PhysicsUniversity of Science and Technology of China
会议名称：《第十五届全国化学动力学会议》
会议日期：2017年
学科分类：081704[工学-应用化学] 07[理学] 08[工学] 0817[工学-化学工程与技术] 070302[理学-分析化学] 0703[理学-化学] 070301[理学-无机化学]
关 键 词：YO high-resolution spectra laser excitation spectrum dispersed fluorescence spectrum
摘 要：Yttrium oxide(YO) is an important constitute in atmospheres of cool stars, and has long been considered as a key indicator in defining the S-type stars. It is also one of the benchmark molecules used for laser cooling and molecular trapping in a magneto-optical trap(MOT). Here, we present the high resolution spectroscopic study on the DΣ–XΣ electronic transition of YO in the 400–440 nm region using laser induced fluorescence. YO molecules are produced by corona discharge of oxygen between the tips of two yttrium needles in a supersonic jet expansion. An unambiguous spectroscopic identification of the DΣ–XΣ transition becomes possible from a combined analysis of the moderate-resolution laser excitation spectrum and dispersed fluorescence spectrum. By using a home-made KTP crystal based single-longitude-mode optical parametric oscillator(OPO) as a narrowband light source, we have also recorded spectra of DΣ–XΣ(0, 0) and(1, 0) bands with a spectral resolution of 0.018 cm, which allows to fully resolve the spin-rotational fine structure and partially resolve hyperfine nuclear spin splitting in the experimental spectra. Accurate spectroscopic constants for DΣ v′ = 0 and 1 levels have been determined from a rotational analysis of the high resolution spectra. Severe perturbations are observed in the experimental spectra, and are considered to originate from interactions with at least one nearby Π electronic state, e.g., the undetected CΠ state. We have also measured the radiative lifetimes of BΣ v’ = 0, and DΣ v’ = 0 and 1 states for the first time, based on which the BΣ–XΣ(0, 0) and DΣ–XΣ(0/1, 0) band oscillator strengths have been determined. The spectroscopic data presented here are of implications in astronomical observations of YO molecules in atmospheres of exoplanets and cool stars.