http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Lee, Jeongmook,Ahn, Doo-Sik,Kim, Sang Kyu American Chemical Society 2013 The journal of physical chemistry. A, Molecules, s Vol.117 No.10
<P>The photoionization of Cr at excited states is investigated using a velocity-map photoelectron imaging technique. Benzene chromium carbonyl or bis(η<SUP>6</SUP>- benzene) chromium was used as a precursor for the generation of excited Cr atoms. The a <SUP>5</SUP>S<SUB>2</SUB> → x <SUP>5</SUP>P°<SUB>3</SUB> and a <SUP>5</SUP>D<SUB>3</SUB> → y <SUP>5</SUP>D°<SUB>2</SUB> transitions are then employed for the preparation of resonant intermediate states in a two-color two-photon ionization process, in which an electronic configurational change from 3d<SUP>4</SUP>(<SUP>5</SUP>D)4s4p(<SUP>1</SUP>P°) to 3d<SUP>4</SUP>4s(<SUP>6</SUP>D<SUB><I>J</I>+</SUB>) occurs. The photoelectron kinetic energy distribution is found to be very sensitive to the ionization energy and the total angular momentum quantum number of the chromium ion (<I>J</I><SUP>+</SUP>). Anisotropy parameters associated with departing electrons also show significant variation depending on the energy and total angular momentum quantum number, suggesting that direct and/or indirect ionization should be quantum-mechanically mixed, manifesting the complicated nature of angular momentum couplings in the ionization continuum.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jpcafh/2013/jpcafh.2013.117.issue-10/jp309211b/production/images/medium/jp-2012-09211b_0008.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/jp309211b'>ACS Electronic Supporting Info</A></P>
Surface Characterization of ε-particle, Trivalent- and Tetravalent-metal Doped Uranium Dioxide
Jeongmook Lee,Dong Woo Lee,Junghwan Park,Tae-Hyeong Kim,Jong-Yun Kim,Sang Ho Lim 한국방사성폐기물학회 2023 한국방사성폐기물학회 학술논문요약집 Vol.21 No.2
This study explores the impact of metal doping on the surface structure of spent nuclear fuels (SNFs), particularly uranium dioxide (UO2). SNFs undergo significant microstructural changes during irradiation, affecting their physical and chemical properties. Certain elements, including actinides and lanthanides, can integrate into the UO2 lattice, leading to non-stoichiometry based on their oxidation state and environmental conditions. These modifications are closely linked to phenomena like corrosion and oxidation of UO2, making it essential to thoroughly characterize SNFs influenced by specific element doping for disposal or interim storage decisions. The research employs X-ray diffraction (XRD), scanning electron microscopy (SEM), and Raman spectroscopy to investigate the surface structure of UO2 samples doped with elements such as Nd3+, Gd3+, Zr4+, Th4+, and ε-particles (Mo, Ru, Pd). To manufacture these samples, UO2 powders are mixed and pelletized with the respective dopant oxide powders. The resulting pellet samples are sintered under specific conditions. The XRD analysis reveals that the lattice parameters of (U,Nd)O2, (U,Gd)O2, (U,Zr)O2, and (U,Th)O2 linearly vary with increasing doping levels, suggesting the formation of solid solutions. SEM images show that the grain size decreases with higher doping levels in (U,Gd)O2, (U,Nd)O2, and (U,Zr)O2, while the change is less pronounced in (U,Th)O2. Raman spectroscopy uncovers that U0.9Gd0.1O2-x and U0.9Nd0.1O2-x exhibit defect structures related to oxygen vacancies, induced by trivalent elements replacing U4+, distorting the UO2 lattice. In contrast, U0.9Zr0.1O2 shows no oxygen vacancy-related defects but features a distinct peak, likely indicating the formation of a ZrO8-type complex within the UO2 lattice. ε-Particle doped uranium dioxide shows minimal deviations in surface properties compared to pure UO2. This structural characterization of metal-doped and ε-particle-doped UO2 enhances our understanding of spent nuclear fuel behavior, with implications for the characterization of radioactive materials. This research provides valuable insights into how specific element doping affects the properties of SNFs, which is crucial for managing and disposing of these materials safely.
Lee, Jeongmook,Kim, So-Yeon,Kim, Sang Kyu American Chemical Society 2014 The Journal of physical chemistry A Vol.118 No.10
<P>Two distinct rotational isomers of thioanisole-<I>d</I><SUB>1</SUB> (C<SUB>6</SUB>H<SUB>5</SUB>S-CH<SUB>2</SUB>D) and thioanisole-<I>d</I><SUB>2</SUB> (C<SUB>6</SUB>H<SUB>5</SUB>S-CHD<SUB>2</SUB>) with respect to the internal rotation of the methyl moiety have been identified and characterized spectroscopically using the resonantly enhanced two photon ionization, UV–UV hole burning, and slow-electron velocity map imaging techniques. From the statistical weights, the definite assignment for the specific rotational isomer of each isotopomer has been successfully done, providing isomer-specific ionization energies and vibrational frequencies of S<SUB>1</SUB>/D<SUB>0</SUB> states. Detailed molecular structures, the methyl internal-rotor barrier, and normal-mode descriptions for selective vibrations are discussed with the aid of density functional theory calculations.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jpcafh/2014/jpcafh.2014.118.issue-10/jp5003676/production/images/medium/jp-2014-003676_0008.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/jp5003676'>ACS Electronic Supporting Info</A></P>
Lee, Jeongmook,Kim, Jandee,Youn, Young-Sang,Liu, Nazhen,Kim, Jong-Goo,Ha, Yeong-Keong,Shoesmith, David W.,Kim, Jong-Yun ELSEVIER 2017 JOURNAL OF NUCLEAR MATERIALS Vol.486 No.-
<P><B>Abstract</B></P> <P>The U<SUB>1−y</SUB>Gd<SUB>y</SUB>O<SUB>2−x</SUB> solid solutions with y = 0.005, 0.01, 0.03, 0.05 and 0.1 were characterized by Raman spectroscopy to investigate the defect structure induced by oxygen vacancies. The oxygen deficiencies of solid solutions were estimated by the relation between the doping level and a lattice parameter calculated from X-ray diffraction patterns. Raman mode shifts to higher wavenumber with increasing doping level showed that crystal lattice disorder due to oxygen vacancies. The frequency shifts and relative ratio of Raman modes were enabled to be the indicator for composition, defect and oxygen vacancy of U<SUB>1−y</SUB>Gd<SUB>y</SUB>O<SUB>2−x</SUB> solid solutions.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Investigation of structural character of U<SUB>1−y</SUB>Gd<SUB>y</SUB>O<SUB>2−x</SUB> solid solutions. </LI> <LI> Defect structures in U<SUB>1−y</SUB>Gd<SUB>y</SUB>O<SUB>2−x</SUB> solid solutions were evaluated by Raman spectroscopy. </LI> <LI> Oxygen deficiency due to Gd content causes Raman band related to oxygen vacancy. </LI> </UL> </P>