http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Ki-jeong Kim,Yong Han,Junfa Zhu,Seulki Roh,Li Liu,Guijie Zhu,Wuyou Fu,Haibin Yang 한국물리학회 2016 Current Applied Physics Vol.16 No.9
In this paper, a new thin film photocatalysts of Ti/TNT/N-I-P/NaTaO3 (the nanostructures is Ti/TiO2/TiO2- PbS-NiO/NaTaO3) is designed for photocatalytic water splitting. This photocatalysts can separate the evolution gas of H2 and O2 into the different sides of the Ti substrate. It is because that the p-i-n junction can separate and transport the photogenerated electrons and holes to their opposing reaction centers. Moreover, these thin film photocatalysts can be recycled again. Which is different from traditional powdered photocatalysts. The photocatalytic activities for water splitting show that the amounts of evolved gas of Ti/TNT/N-I-P/NaTaO3 is 8.73 mmol/h cm2 under high-pressure mercury lamp illuminations, which is 7 times higher than that of Ti/NaTaO3 thin film photocatalysts. Two aspects can contribute to this performance: the one is the structure of N-I-P/NaTaO3; the other one is electrical conduction layer TNT. This study provides a new insight into synthesis of thin film photocatalysts to liberate H2 and O2 separately from H2O.
Purine on graphene: PES and NEXAFS study of a heterocyclic aromatic organic compound
Ki-jeong Kim,Yong Han,Junfa Zhu,Jaeyoon Baik,Hyunjun Shin,Hangil Lee,Bongsoo Kim 한국물리학회 2016 Current Applied Physics Vol.16 No.9
We have investigated the properties of a self-assembled purine (C5H4N4) monolayer on epitaxial graphene (EG) on SiC by using high resolution X-ray photoemission spectroscopy (HRPES) and near-edge Xray absorption of fine structure (NEXAFS). The monolayer of purine on graphene was prepared inside a UHV chamber. The spontaneously-assembled monolayer of purine molecules were oriented parallel to the surface of the monolayer graphene, and it reaches a charge equilibrium state on the monolayer graphene.
11B pulsed nuclear magnetic resonance study of DyNi2B2C single crystals
Ki-jeong Kim,Yong Han,Junfa Zhu,Seulki Roh 한국물리학회 2016 Current Applied Physics Vol.16 No.9
DyNi2B2C is the only compound in the RNi2B2C (R ¼ rare-earth element) series where superconductivity at Tc ~6.2 K coexists with the antiferromagnetic ordering below the Neel temperature TN ~10.3 K. This system is of great interest because superconductivity rarely coexists with magnetic ordering. 11B pulsed nuclear magnetic resonance (NMR) measurements were performed at 8.0056 T to investigate the local electronic structures and 4f spin dynamics of DyNi2B2C powders and single crystals. The spectrum for the single crystal showed three narrow resonance peaks at 295 K due to the nuclear Zeeman splitting of a nuclear spin I ¼ 3/2 with quadrupolar perturbation. The 11B NMR Knight shift of the single crystal was very large and highly anisotropic at K ¼ 0.60% and þ0.27% for the fields parallel and perpendicular, respectively, to the c-axis at 295 K. Considering the anisotropy of the Knight shift, we were able to simulate the 11B NMR power pattern that agreed well with the measured spectrum. The linewidth for DyNi2B2C was also large and anisotropic, and the linewidth value increased rapidly at low temperatures. The 11B NMR shift and linewidth were found to be proportional to the magnetic susceptibility, indicating that the hyperfine field at the B site originates from the 4f spins of Dy. Above TN, the values for 1/T1 (the spin-lattice relaxation rate) and 1/T2 (the spin-spin relaxation rate) were very large, showing slight increases at low temperatures. Below TN, the values of 1/T1 and 1/T2 were suppressed significantly because of the slowing of the 4f spin fluctuation. This confirmed the huge change in Dy 4f spin dynamics across the antiferromagnetic transition.
Ki-jeong Kim,Yong Han,Junfa Zhu,Seulki Roh,Jungseek Hwang 한국물리학회 2016 Current Applied Physics Vol.16 No.9
We investigated Ni-doped Ba-122 pnictide single crystals at two different doping levels (BaFe2xNixAs2; x ¼ 0.05 (underdoped) and 0.10 (optimally doped)) using optical spectroscopy. We analyze measured optical data with an extended Drude model and a generalized Allen’s formalism. We extracted the electron-boson spectral density function using an approximate single-band approach from measured optical scattering rate. We observed that an anomalous behavior in the coupling constant obtained from the electron-boson spectral density function takes place near the magnetic transition temperature of the underdoped sample. This anomaly has not been observed in cuprate system. Nevertheless, overall temperature and doping dependent properties of the electron-boson spectral density of pnictides are similar to those of cuprates. This may indicate that these two different high-temperature superconducting systems share a same mechanism for their superconductivity.
Steric effects of CO2 binding to transition metal-benzene complexes: A first-principles study
Ki-jeong Kim,Yong Han,Junfa Zhu 한국물리학회 2016 Current Applied Physics Vol.16 No.9
Using density functional theory (DFT) calculations, we investigated the adsorption of CO2 molecules on 3d transition metal (TM)-benzene complexes. Our calculations show that the maximum number of CO2 molecules adsorbable on Sc or Ti atoms is three, but the 18-electron rule predicts it should be four. The 18-electron rule is generally successful in predicting the maximum H2 adsorption number for TM atoms including Sc or Ti atoms. We found that the 18-electron rule fails to correctly predict CO2 binding on Scor Ti-benzene complexes because CO2 binding, in contrast to H2 binding, requires additional consideration for steric hindrance due to the large bond length of CO2. We calculated the occupation function for CO2 using the Tolman cone angle, which shows that three CO2 molecules fully occupy the available space around Sc- and Ti-benzene complexes. This estimation is the same maximum CO2 adsorption number predicted by DFT calculations. Therefore, we propose that the occupation function for CO2 using the Tolman cone angle is an efficient model for evaluating steric hindrance of CO2 adsorption on a surface.