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RISS 인기검색어
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- 주제어 : isomer shift (검색결과 3 건)
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Thermal cis-trans isomerization of triazo-benzene
Choi, Y.W.,Lim, Y.K.,Lee, S.U.,Cho, C.G.,Lee, Y.,Sohn, D. Elsevier 2007 Current Applied Physics Vol.7 No.5
1,3,5-Hydroxy-triazo-benzene (H-TAB) was synthesized through a coupling-oxidation protocol. Temperature-controlled UV, IR, and ab initio calculation were carried out to investigate the cis-trans thermal isomerization of H-TAB. In temperature-controlled UV experiments, λ<SUB>max</SUB> of the π-π<SUP>*</SUP> band and for the trans conformation at 335nm and that for the cis form at 282nm are shifted by increased temperature; band intensities of the π-π<SUP>*</SUP> transition decrease and λ<SUB>max</SUB> of the π-π<SUP>*</SUP> band is shifted toward the high-energy region. The maximum peak at 2922cm<SUP>-1</SUP> is shifted to 2926cm<SUP>-1</SUP>, and that at 2852cm<SUP>-1</SUP> is shifted to 2856cm<SUP>-1</SUP> at increased temperature in the temperature-controlled IR experiment. Ab initio calculation reveals that the cis conformation of H-TAB is more stable than the trans form because the cis form has less spatial repulsion. Therefore, the ground-state energy difference induced by steric repulsion of the benzene unit is the driving force of the blue shift in the thermal IR and UV spectra for the triazo-benzene.
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Fe0.9Zn0.1Cr₂S₄의 결정학적 및 자기적 성질에 관한 연구
배성환(Sung Hwan Bae),김삼진(Sam Jin Kim),김철성(Chul Sung Kim) 한국자기학회 2007 韓國磁氣學會誌 Vol.17 No.1
Fe0.9Zn0.1Cr₂S₄ 를 직접합성법으로 제조하여 X-선 회절기(XRD), 진동 시료 자화율 측정기(VSM), Mössbauer 분광기를 이용하여 시료의 결정학적 및 자기적 특성을 연구하였다. X-선 회절도 분석 결과, 결정구조는 입방정형 스피넬 구조이며, 공간 그룹은 Fd3m으로 격자 상수는 a₀ = 9.9967 Å로 결정되었다. 100 Oe 인가자장하의 자화 곡선(ZFC: Zero field cooling)에서는 77 K 근방에서 첨점 형태의 특이 현상이 관측되었다. VSM과 Mössbauer 스펙트럼 분석 결과 Néel 온도(TN)는 153 K로 결정되었다. Mössbauer 스펙트럼은 4.2 K에서 커다란 전기 사중극자 상호작용에 의한 비대칭적인 8-line 형태를 나타내었으며 이때의 전기 사중극자 분열치는 2.22 ㎜/s이었다. 77 K에서 전기 사중극자 분열치는 0.20 ㎜/s로 급격히 감소하였고 온도 상승과 함께 Mössbauer 스펙트럼 또한 8-line에서 6-line 형태로 변하였다. 상온에서의 이성질체 이동 값은 0.48 ㎜/s로 철의 이온 상태가 전온도 영역에서 Fe2+로 결정되어 진다. The crystallographic and magnetic properties of Fe0.9Zn0.1Cr₂S₄ have been studied by X-ray diffractometer (XRD), vibrating sample magnetometer (VSM) and Mössbauer spectroscopy measurement. The crystal structure was determined by the normal cubic spinel of space group Fd3m and the lattice constant was a₀ = 9.9967 Å. The specific phenomenon which looks like cusp pattern at 77 K was observed in magnetization curves (ZFC : Zero Field Cooling) under 100 Oe applied field. Neél temperature (TN) was determined to be 153 K by VSM and Mössbauer spectra. The asymmetric 8-line profile has been observed at 4.2 K, which was attributed by the colossal electric quadrupole interaction (∆EQ), ∆EQ has 2.22 ㎜/s at 4.2 K. The ∆EQ abruptly decreases around 77 K and then it disappears above 77 K with diminishing of 8-line pattern. The isomer shift δ at room temperature is 0.48 ㎜/s relative to Fe metal, which means that the charge state of Fe ions is ferrous in character.
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Mo¨ssbauer Spectroscopy에 衣한 Hamatinics內의 鐵의 酸化狀態 및 Spin狀態의 硏究
洪致裕,黃鎭澈,尹仁燮 동국대학교 산업기술대학원 1993 산업기술논문집 Vol.1 No.-
Mo¨ssbauer spectroscopy has been carried out to investigate the ionic states of Fe atoms contained in the hematinics. From the Mo¨ssbauer parameters we can define the hyperfine interactions of Fe atoms with surrounding elements related to Fe ionic states. The Fe in the sample used as hematinics usually exist in the S=2 high spin state of Fe^(+2) or in the S=1/2 low spin state of Fe^(+3). In this study we knew that Fe^(+2) state was preferable to Fe^(+3) state on the hematinics.
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