Korea Advanced Institute of Science and Technology · Chemistry
Professor Jong-Il Yun's research lab specializes in advanced spectroscopic techniques for environmental and nuclear materials analysis, with a focus on actinide and rare earth element speciation in complex aqueous and solid-state systems. The lab employs time-resolved laser fluorescence spectroscopy (TRLFS), laser-induced breakdown spectroscopy (LIBS), and X-ray absorption spectroscopy (EXAFS) to investigate the speciation, stability, and coordination environments of uranium, plutonium, and europium in conditions relevant to nuclear waste management and high-level waste vitrification. Key research directions include the formation of ternary metal-ligand complexes (e.g., Ca-UO₂-CO₃, Mg-UO₂-CO₃), the selective detection of solid-phase rare earth oxides in solution, and real-time multielement monitoring of molten glass during vitrification processes.
Figures are computed from collected data and may differ slightly.
The chemical behavior of ternary Ca-UO2-CO3 complexes was investigated by using time-resolved laser fluorescence spectroscopy (TRLFS) in combination with EDTA complexation at pH 7-9. A novel TRLFS revealed two distinct fluorescence lifetimes of 12.7 ± 0.2 ns and 29.2 ± 0.4 ns for uranyl complexes which were formed increasingly dependent upon the calcium ion concentration, even though nearly indistinguishable fluorescence peak shapes and positions were measured for both Ca-UO2-CO3 complexes. For
Laser-induced breakdown spectroscopy (LIBS) was applied to selectively analyze the aqueous suspension of Eu 2 O 3 (s) particles in the presence of the Eu 3+ aquo ion. A plasma was generated by focusing a pulsed Nd:YAG laser beam (λ = 532 nm) into the sample. The light emission from the plasma was detected by a spectrograph equipped with a gated intensified charge-coupled device (ICCD) in the wavelength range of 275–525 nm. The atomic emission intensity of the Eu 2 O 3 (s) suspension was about tw
The paper presents the application of laser-induced breakdown spectroscopy (LIBS) for the on-line multielement analyses of glass melts in a vitrification process of high level liquid waste (HLLW). The third harmonic pulse of an Nd:YAG laser is used for the generation of plasma on the molten glass surface and the plasma emission is monitored by an echelle spectrometer with an intensified charge-coupled device (ICCD), which simultaneously covers the wavelength range from 200 to 780 nm. Twelve diff
Laser-induced breakdown spectroscopy (LIBS) is presented for the on-line multielement analysis of molten radioactive glass at a simulated vitrification process of high level liquid waste (HLLW). A plasma plume is produced by focusing the third harmonic of a Nd: YAG laser (λ = 355 nm) onto the glass melt surface at 1200 °C, and the plasma emission is guided via optical fiber and is characterized by an echelle spectrometer for the spectral range from 200 to 780 nm with a resolution of ±0.01 nm. Co
Abstract The formation of ternary Mg-UO 2 -CO 3 complexes under weakly alkaline pH conditions was investigated by time-resolved laser fluorescence spectroscopy (TRLFS) and extended X-ray absorption fine structure (EXAFS) and compared to Ca-UO 2 -CO 3 complexes. The presence of two different Mg-UO 2 -CO 3 complexes was identified by means of two distinct fluorescence lifetimes of 17±2 ns and 51±2 ns derived from the multi-exponential decay of the fluorescence signal. Slope analysis in terms of fl
The hydrolysis of tetravalent plutonium in 0.5 M HCl/NaCl has been investigated by a combination of spectroscopy and redox potential measurements in the concentration range from 10 -5 to 4×10 -4 M and at pH c 0.3–2.1. Redox potentials were both measured and calculated from the plutonium oxidation state distributions using well-known equilibrium constants for the redox reactions of plutonium. The plutonium oxidation states in solution were quantified by spectroscopy. The p e values calculated fro
Electrochemical and spectroscopic properties of Tb(III) in molten LiCl–KCl eutectic at high temperature were investigated by cyclic voltammetry and time-resolved laser-induced fluorescence spectroscopy (TRLFS). The diffusion coefficient of Tb(III) and the formal standard potential of Tb(III)/Tb0 were determined to be 2.06 ± 0.4 × 10− 5 cm2 s− 1 and − 2.83 ± 0.03 V vs. Cl2/Cl− at 887 K, respectively. Additionally, visible fluorescence of Tb(III) due to the electronic transitions from 5D3 and 5D4
The ternary complexation of calcium uranyl tricarbonate species, CaUO<sub>2</sub>(CO<sub>3</sub>)<sub>3</sub><sup>2-</sup> and Ca<sub>2</sub>UO<sub>2</sub>(CO<sub>3</sub>)<sub>3</sub>(aq), which are the predominant U(vi) complexes in groundwater and seawater, was investigated at variable temperatures from 10 to 70 °C. Time-resolved laser fluorescence spectroscopy (TRLFS), calcium ion-selective electrode potentiometry, and ultraviolet/visible (UV/Vis) absorption spectroscopy were complementarily
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