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RISS 인기검색어
- 검색키워드
- 저자 : Baik Jaeyoon (검색결과 34 건)
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Adsorption of Benzenethiol and 1,4-Benzenedithiol on the Si(111)-7 X 7 Surface
Jaeyoon Baik,박종윤,Bongsoo Kim,Chan-Cuk Hwang,Han-Na Hwang,Jong Yeol Ahn,Jungwoon Park,Ki-Seok An,Minkook Kim 한국물리학회 2007 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.50 No.3
Benzenethiol- and 1,4-benzenedithiol-adsorbed Si(111)-7~$\times$~7 surfaces were studied by using scanning tunneling microscopy and synchrotron radiation photoemission spectroscopy, which showed that benzenethiol molecules were adsorbed on Si adatoms with upright structures and 1,4-benzenedithiol molecules on two adjacent Si adatoms with a bridging structure. At the initial stage, the adsorptions can be understood by a dissociative process between sulfur and hydrogen on the Si atoms. Here, sulfur bonds to the electrophilic adatoms while hydrogen bonds to neighboring nucleophilic restatoms. On the other hand, this adsorption mechanism during the initial stage does not apply at higher exposures of molecules, as is noticed from the photoemission spectra. Benzenethiol- and 1,4-benzenedithiol-adsorbed Si(111)-7~$\times$~7 surfaces were studied by using scanning tunneling microscopy and synchrotron radiation photoemission spectroscopy, which showed that benzenethiol molecules were adsorbed on Si adatoms with upright structures and 1,4-benzenedithiol molecules on two adjacent Si adatoms with a bridging structure. At the initial stage, the adsorptions can be understood by a dissociative process between sulfur and hydrogen on the Si atoms. Here, sulfur bonds to the electrophilic adatoms while hydrogen bonds to neighboring nucleophilic restatoms. On the other hand, this adsorption mechanism during the initial stage does not apply at higher exposures of molecules, as is noticed from the photoemission spectra.
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Direct Visualization of a Cycloaddition Reaction on Frozen Asymmetric Si Dimers at Room Temperature
Jaeyoon Baik,임규욱,Taekyun Ha,Ki-Seok An,Joung Real Ahn,Chong-Yun Park 한국물리학회 2016 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.69 No.1
We firstly report an experimental visualization of a cycloaddition reaction on RT frozen asymmetric Si dimers. The frozen Si dimers with a local c(4 × 2) order were prepared by pinning flip-flopping Si dimers by using molecules. This RT pristine c(4 × 2) structure was used to determine what Si atom of an asymmetric Si dimer bonds to a molecule at the initial stage of the RT cycloaddition reaction, which has been a long-standing puzzling issue. This made it possible to compare directly experimental cycloaddition reactions with theoretical ones. As a prototype for the experiment, a 1,3-butadiene molecule adsorbed between Si dimer rows was used. The 1,3-butadiene molecule was found to prefer a symmetric Si pair on the frozen Si dimers, i.e., two electrophilic lower atoms of asymmetric Si dimers. This result is consistent with the theoretical prediction that a 1,3-diene molecule prefers a symmetric Si pair on the Si(001)c(4 × 2) surface. This experimental approach can also be applied to other studies for the adsorption of a molecule on a Si(001) surface at room temperature.
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백재윤(Jaeyoon Baik),김대현(Daehyun Kim) 한국진공학회 2022 진공 이야기 Vol.9 No.1
The development of various nanoscience and nanotechnology over the past decades has progressed complementarily with the development of microscopic technology. In particular, SPEM (Scanning Photoelectron Microscopy) is developing into a powerful tool for material analysis and characterization using well-established synchrotron radiation technology. Beam focusing optical technology for SPEM has reached 50 nm beyond 100 nm in continuous efforts to realize the maximum spatial resolution that is difficult for conventional XPS to achieve. As a result, the utilization of this experimental technique is increasing as the field of research on flake-type low-dimensional materials has expanded rapidly. Furthermore, the value of use in research on next-generation all solid states secondary batteries is also increasing as it has recently evolved into a research technique incorporation measurement technique in an operando environment such as driving a voltage-applied device. In this report, we introduce the fundamental measurement principle of SPEM and several research results using SPEM.
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Park, Woanseo,Baik, Jaeyoon,Kim, Tae-Young,Cho, Kyungjune,Hong, Woong-Ki,Shin, Hyun-Joon,Lee, Takhee American Chemical Society 2014 ACS NANO Vol.8 No.5
<P>Molybdenum disulfide (MoS<SUB>2</SUB>) films, which are only a single atomic layer thick, have been synthesized by chemical vapor deposition (CVD) and have gained significant attention due to their band-gap semiconducting properties. However, in order for them to be useful for the fabrication of practical devices, patterning processes that can be used to form specific MoS<SUB>2</SUB> structures must be integrated with the existing synthetic approaches. Here, we report a method for the synthesis of centimeter-scale, high-quality single-layer MoS<SUB>2</SUB> that can be directly patterned during CVD, so that postpatterning processes can be avoided and device fabrication can be streamlined. Utilizing X-ray photoelectron spectroscopic imaging, we characterize the chemical states of these CVD-synthesized single-layer MoS<SUB>2</SUB> films and demonstrate that the triangular-shaped MoS<SUB>2</SUB> are single-crystalline single-domain monolayers. We also demonstrate the use of these high-quality and directly patterned MoS<SUB>2</SUB> films in electronic device applications by fabricating and characterizing field effect transistors.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/ancac3/2014/ancac3.2014.8.issue-5/nn501019g/production/images/medium/nn-2014-01019g_0008.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nn501019g'>ACS Electronic Supporting Info</A></P>
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Kang, Se-Jun,Baik, Jaeyoon,Shin, Hyun-Joon Elsevier 2014 Current Applied Physics Vol.14 No.1
Thin Au layers (0.04 nm, 0.06 nm, 0.08 nm, 0.21 nm) were deposited on an amorphous In-Ga-Zn-O (a-IGZO) thin-film surface by thermal evaporation in an ultrahigh vacuum. The chemical-state changes of the Au layer and the a-IGZO surface were investigated by measuring the Au 4f, O 1s, In 3d, Ga 3d and Zn 3d peaks as well as the valence bands by soft X-ray photoelectron spectroscopy. Upon initial deposition, an oxidized Au component formed, whereas a metallic Au component was dominant. At the later deposition stages, the metallic Au component dominated the spectral features. When the Au thickness was thicker than 0.08 nm, a split Au 5d feature was apparent. And as the Au thickness continued to increase, In 3d showed a strong lower-binding-energy (lower-BE) component; the Ga 3d and Zn 3d also showed lower-BE components, but of much reduced intensities relative to In 3d. These results seem to imply that compared with other elements, Au atoms prefer to occupy oxygen vacancies and strongly interact with In atoms. (C) 2013 Elsevier B.V. All rights reserved.
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Lee Na-Kyoung,Won Samuel Jaeyoon,Lee Jun-Young,Kang Seung-Baik,Yoo So Young,Chang Chong Bum 대한의학회 2022 Journal of Korean medical science Vol.37 No.43
Background: A considerable proportion of patients warranting total knee arthroplasty (TKA) have night pain, neuropathic pain, and/or depressive disorder, which may not be resolved by TKA. This prospective, longitudinal cohort study aimed to document the prevalence of night pain, neuropathic pain, and depressive disorder in patients with advanced knee osteoarthritis undergoing TKA and to determine whether the specific coexisting pain and/or disorder at the time of TKA adversely affected postoperative outcomes. Methods: In this study, 148 patients undergoing TKA were longitudinally evaluated. The presence of night pain, neuropathic pain (determined using Douleur Neuropathique 4 [DN4]) and depressive disorder (determined using the Patient Health Questionnaire-9 [PHQ-9]) was determined before and 6 weeks, 3 months and 1 year after TKA. In addition, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and EuroQol-5 Dimension (EQ-5D) scores were assessed before and 1 year after TKA. Potential associations of night pain, neuropathic pain, and/or depressive disorder with pre- and postoperative WOMAC and EQ-5D scores were examined in subgroup analyses. Results: Preoperatively, 72% (n = 106) of patients reported night pain, and the prevalences of neuropathic pain and depressive disorder were 15% and 17%, respectively. Preoperatively, compared with patients without night pain, those with night pain had significantly poorer preoperative WOMAC scores, but no significant difference was seen between groups 1 year after TKA. Preoperatively, the WOMAC, EQ-5D, and EQ-5D health scores of patients with neuropathic pain were not significantly different from those of patients without neuropathic pain, and there was no difference in clinical outcome scores 1 year after TKA between these groups. Preoperatively, the patients with depressive disorder showed significantly poorer preoperative WOMAC, EQ-5D, and EQ-5D health scores than those without depressive disorder, but no significant differences in scores were observed 1 year after TKA between these groups. Conclusion: This study revealed a considerable prevalence of night pain, neuropathic pain, and depressive disorder in patients undergoing TKA and that patients with these specific conditions reported poorer functional and quality of life scores preoperatively. However, such adverse effects disappeared after TKA. Our study findings suggest that TKA can provide satisfactory outcomes for patients with these specific conditions.
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Kim, Yeonwoo,Yang, Sena,Jeon, Eun Hee,Baik, Jaeyoon,Kim, Namdong,Kim, Hyun Sung,Lee, Hangil Springer US 2016 NANOSCALE RESEARCH LETTERS Vol.11 No.1
<P>To design a high-performance photocatalytic system with TiO<SUB>2</SUB>, it is necessary to reduce the bandgap and enhance the absorption efficiency. The reduction of the bandgap to the visible range was investigated with reference to the surface distortion of anatase TiO<SUB>2</SUB> nanoparticles induced by varying Fe doping concentrations. Fe-doped TiO<SUB>2</SUB> nanoparticles (Fe@TiO<SUB>2</SUB>) were synthesized by a hydrothermal method and analyzed by various surface analysis techniques such as transmission electron microscopy, Raman spectroscopy, X-ray diffraction, scanning transmission X-ray microscopy, and high-resolution photoemission spectroscopy. We observed that Fe doping over 5 wt.% gave rise to a distorted structure, i.e., Fe<SUB>2</SUB>Ti<SUB>3</SUB>O<SUB>9</SUB>, indicating numerous Ti<SUP>3+</SUP> and oxygen-vacancy sites. The Ti<SUP>3+</SUP> sites act as electron trap sites to deliver the electron to O<SUB>2</SUB> as well as introduce the dopant level inside the bandgap, resulting in a significant increase in the photocatalytic oxidation reaction of thiol (–SH) of 2-aminothiophenol to sulfonic acid (–SO<SUB>3</SUB>H) under ultraviolet and visible light illumination.</P><P><B>Electronic supplementary material</B></P><P>The online version of this article (doi:10.1186/s11671-016-1263-6) contains supplementary material, which is available to authorized users.</P>
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