The Laser-Induced Fluorescence Spectrum of Gold Monoxide (AuO): b4Π3/2-X2Π3/2 Transition
XIANG Qian-lan1, 2, YANG Jie3, HUA Xue-xia1, ZHANG Ji-cai3, MA Xin-wen3
1. Ion Beam & Optical Physical Joint Laboratory of Xianyang Normal University and Institute of Modern Physics, Chinese Academy of Sciences, Xianyang 712000, China
2. Department of Applied Physics, Xi’an Jiaotong University, Xi’an 710049, China
3. Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China
Abstract：Studying Au—O bond can provide an insight into the rapidly expanding field of gold chemistry. AuO is the simplest model containing Au—O bond. So, it is of great scientific significance to study the electronic structure of gold oxide molecule. Laser induced fluorescence spectroscopy is an effective means to study molecular structures and chemical bonds. In this paper laser ablation combined with ultrasonic jet technology was used to produce gas phase gold monoxide, and the electronic spectrum of the gaseous gold monoxide molecule (AuO) had been investigated in the range of 16 500～18 500 cm-1 using laser induced fluorescence spectroscopy. The ablation laser (Leibao Dawa-300) sputtered pure gold target (99.9%) which was controlled by a vacuum motor for rotation to produce Au atoms. The pure high pressure O2 was injected into the vacuum chamber through a molecular beam pulse valve (Parker, General Valve, series 9) to react with the gold vapor to form AuO. A dye laser (Sirah, Cobra-Stretch) was pumped by Nd∶YAG laser (Continuum Surelite II-10) and the output of the pulsed dye laser (linewidth 0.05 cm-1, pulse duration 5 ns, energy 0.1 mJ·pulse-1) was introduced into the vacuum chamber to excite AuO. The fluorescence from the excited AuO radical was imaged through appropriate low-pass cutoff filters into a photomultiplier tube (PMT) detector (EMI, ET9202QB). Pulsed analog signals from the PMT were converted into digital signals by a fast digital oscilloscope card (Picoscope 6404C, 500 MHz, 14 bits) and recorded by a data acquisition program based on LabVIEW of our own. The detected bands with band heads at 17 152.94，17 552.17，17 932.78 and 18 291.62 cm-1 were attributed to b4Π3/2(v′=0，1，2，3)-X2Π3/2(v″=0) transitions. The molecular constants including rotational constants and centrifugal distortion constants were determined by analyzing the rotationally resolved spectra. The possible electronic configuration of the excited state is 1σ21π41δ42σ12π33σ*1.
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