Diatomic Molecular Emission Spectroscopy of Laser-induced Titanium Plasma

22nd International Conference on Spectral Line Shapes

Woods, A.C.^1 ; Parigger, C.G.^1

University of Tennessee, Space Institute, 411 B. H. Goethert Pkwy, Tullahoma

TN

37388, United States^1

关键词: Characteristic time;    Laser induced plasma;    Laserinduced breakdown spectroscopy (LIBS);    Molecular transitions;    Optical emission spectroscopies (OES);    Spectral measurement;    Spectral transitions;    Temperature increase;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/548/1/012037/pdf
DOI  :  10.1088/1742-6596/548/1/012037

来源: IOP

【 摘 要 】

Previous research regarding laser-induced breakdown spectroscopy (LIBS) of titanium normally focuses on the atomic and ionic Ti spectral transition lines. However, after a characteristic time subsequent to laser ablation, these lines are no longer discernable. During this temporal regime, the diatomic molecular transition lines of titanium monoxide (TiO) are prominent in the laser-induced plasma (LIP) emissions. TiO has long been studied in the contexts of stellar emissions, allowing for some of the molecular transition bands to be accurately computed from theory. In this research, optical emission spectroscopy (OES) of laser-induced plasma (LIP) generated by laser ablation of titanium is performed in order to infer temperature as a function of time subsequent to plasma formation. The emission spectra of the resulting ablation plume is imaged as a function of height above the sample surface. Temperatures are inferred over time delays following plasma formation ranging from 20 μs-200 μs. Computed TiO A3Φ-X3Δ, Δv 0 transition lines are fit to spectral measurements in order to infer temperature. At tdelay20 μs-80 μs, the observed plume contains two luminescent regions each with a distinctly different temperature. As the plume evolves in time, the two regions combine and an overall temperature increase is observed.