• Title/Summary/Keyword: 쌍극자모멘트

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Ab Initio Studies on Hydrogen-Bonded Dimers of Fluoromethanes with Ammonia and Water (플루오르화메탄들과 암모니아 및 물과의 수소결합 이량체들에 관한 Ab Initio 연구)

  • Soon-Ki Lee;Seung-Hoon Kim
    • Journal of the Korean Chemical Society
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    • v.37 no.4
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    • pp.408-415
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    • 1993
  • Systematic ab initio SCF calculations have been performed on the hydrogen-bonded dimers of fluoromethanes involving $CH_4,\;CH_3F,\;CH_2F_2\;and\;CHF_3$ with ammonia and water applying basis sets of 9s5p/5s and 9s5p1d/5p1d. Various ground state properties of these stable dimeric complexes have been evaluated. We compared these with corresponding properties of isolated monomers. We report equilibrium geometries, stabilization energies, dipole moments and force constants of intermolecular bonds. The effects arising as a consequence of the non-additive behavior of hydrogen bonding in chain-like oligomers are discussed. Systematic, methodical errors due to the use of the SCF approximation and the basis set dependence of the computed results are pointed out.

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Prediction of Retention Time for PAH Molecule in HPLC (고속액체 크로마토그래피에서 PAH분자의 구조에 따른 용리시간 예측)

  • Kim, Young-Gu
    • Journal of the Korean Chemical Society
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    • v.44 no.2
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    • pp.102-108
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    • 2000
  • Relative retention times (RRTs) of RAH molecules in HPLC are trained and predicted intesting sets using a multiple linear regression (NLR) and an artificial neural network (ANN). The maindescriptors in QSRR are molecular connectivity ($^1X_v,\;^2X_v$), the length-to-breadth ratios (L/B), and molecular dipole moment(D). L/B which is related with slot model is a good descripter in ANN, but isn't in MLR. Varainces which show the accuracy of prediction times in testing sets are 0.0099, 0.0114 for ANN and MLR, respectively. It was shown that ANN can exceed the MLR in prediction accuracy.

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Synthesis of trans, trans-4-(2-Fluoro-3-isothiocyanato-4-propylphenyl)-4-alkylbicyclohexyl for Liquid Crystal Display (액정 디스플레이를 위한 트랜스, 트랜스-4-(2-플르로로-3-아이소싸이오싸이아네이토-4-프로필페닐)-4'-알킬바이싸이클로헥실의 합성)

  • Lee, Seon-Hui;Kim, Seong-Hun
    • Journal of the Korean Chemical Society
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    • v.48 no.5
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    • pp.499-503
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    • 2004
  • We designed and synthesized compounds which have negative dielectric anisotropy (N type) for VA-LCD mode. Due to the large dipole moments toward the minor axis of molecule and anisotropy of polarizability, they can be used as N type LC. F atom and NCS group and propyl group were introduced as substituents on bicyclohexylbenzene core unit and alkyl chains (propyl~heptyl) were introduced on terminal part. All of the synthesized compounds showed negative dielectric anisotropy as expected.

평판형 자기장 발생기를 이용한 자성 나노 파우더 기열에 관한 연구

  • Yu, Jae-Hyeong;Lee, Jae-Seon;No, Jun-Hyeong;Jo, Tae-Hun;Yun, Myeong-Su;Park, Bong-Ju;Choe, Eun-Ha;Gwon, Gi-Cheong
    • Proceedings of the Korean Vacuum Society Conference
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    • 2014.02a
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    • pp.434.1-434.1
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    • 2014
  • 최근 자성 나노 입자를 이용한 온열치료가 주목을 받고 있다. 자성을 띄는 나노 입자를 암 세포에 보내, 교류 자기장을 걸어주어 회전에 의한 마찰손실로 인한 열을 이용하여 암 조직만을 국소 가열하는 원리이다. 본 실험은 유도 자기장을 사용한 자성 나노 파우더의 가열을 목적으로 시행하였다. 나선형 코일위에 세라믹, 유리 등 절연체 원판 위에 자기장이 발생되도록 휴대용 평판형 자기장 발생장치를 제작하였다. 자기장 발생 장치는 평판형 나선형 코일에 특정 주파수를 가진 전원을 인가하여 자기장을 발생시킨다. 평판형 나선형 코일은 내경 40 mm, 외경 140 mm, 2 mm 동선으로 제작하였다. 제작한 자기장 발생장치를 자기장 측정 센서(Hall sensor 등)을 원판 위에 설치하여 거리별 자기장의 크기를 측정하였다. 자기장은 나선형 코일 위 원판 중심에서 최대로 발생되어 중심에서 멀어질수록 크기가 감소하였다. 자기장 발생장치 위에 자성 나노 파우더($Fe_3O_4$$CoFe_2O_4$)를 혼합한 용액 시료를 위치시키고 자기 쌍극자 모멘트와 자기장간의 상호작용을 유도한다. 이때 자성 나노 파우더별로 발생하는 열을 열전쌍(TC)이나 Optical fiber를 사용한 Thermometer로 측정하여 비교분석하였다.

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홀 주입 층으로 사용한 자기조립박막층에 의한 유기발광소자의 효율 향상

  • Kim, Min-Seong;Jeon, Yeong-Pyo;Kim, Tae-Hwan
    • Proceedings of the Korean Vacuum Society Conference
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    • 2014.02a
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    • pp.395.1-395.1
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    • 2014
  • 차세대 디스플레이 소자 기술로 많은 주목을 받고 있는 유기발광소자는 현재 전류효율 향상과 낮은 구동전압과 관련하여 연구가 활발하게 진행되고 있다. 음극과 양극 전극에서 유기물 층으로 전자와 정공의 주입이 많아져도 유기발광 층에서 재결합하는 전자와 정공의 균형이 맞지 않으면 전류 효율과 휘도가 낮아지는 문제점이 있다. 유기발광소자에서 홀 주입 층으로 사용하는 자기조립박막층은 일반적인 유기발광소자에서 정공의 이동도가 낮은 단점을 보완하여 발광층에서 전자와 정공의 균형을 향상하여 전류효율을 향상과 낮은 구동전압 특성을 나타낸다. 본 연구에서는 홀 주입 층으로 사용되는 각각의 자가조립박막을 형성할 물질이 용해되어 있는 에탄올 용액에 ITO를 담가 자가조립박막을 ITO 위에 형성 시킨다. 각각의 홀 주입 층으로 사용된 자가조립박막층의 chain group의 길이와 ITO와 결합하는 head group에 따라 달라지는 쌍극자 모멘트에 의한 홀 주입의 변화를 통해 각 소자의 전류효율과 구동전압 관찰할 수 있었다. 자가조립박막층의 chain group의 길이가 길어질수록 전극으로부터 유기물 층으로의 홀 주입을 방해하여 발광 층에서의 전자와 정공의 재결합 균형이 무너짐으로써 전류효율과 휘도가 낮아지는 경향을 볼 수 있었다. 이 연구 결과는 자가조립박막층을 홀 주입 층으로 대체하는 구조로 유기발광소자의 효율 향상에 대한 기초자료로 활용할 수 있다.

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Study for Energy Transfer from Rhodamine 6G to Malachite Green Using Time Correlated Single Photon Counting Method (시간상관 단일광자 계수법에의한 Rhodamine 6G에서 Malachite Green으로의 에너지 전달 연구)

  • Kim, Hyun-Soo;Eom, Hyo-Soon;Choi, Gyu-Kwan;Jeong, Hong-Sik;Kim, Ung
    • Korean Journal of Optics and Photonics
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    • v.2 no.4
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    • pp.203-208
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    • 1991
  • We investigated the nonradiative energy transfer process from Rhodamine 6G to Malachite Green in ethylen glycol solvent using time correlated single photon counting system equipped with a modelocked Ar ' laser. The reduced concentration and critical transfer distance for various acceptor concentration were obtained by using a full-fitting analysis of the fluorescence decay curves. We found that Huber model is more suitable than Forster model and the influence of energy migration through the dipole-dipole interaction becomes more significant for the low acceptor concentrations relative to the donor concentration($5\times 10^4$mol/l).

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A Study on the Electronic Properties and Electrochemical Behavior of Transition Metal(Ⅳ) Complexes (Ⅳ) (전이금속(Ⅳ) 착물들의 전자적 성질과 전기 화학적 거동에 관한 연구(Ⅳ))

  • Choi, Chil Nam;Son, Hyo Youl
    • Journal of the Korean Chemical Society
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    • v.39 no.5
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    • pp.356-363
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    • 1995
  • The chemical behavior of the transition metal (Nb4+ and Mo4+) complexes with organoligand (dichloro-bis(η-cyclopentadienyl) has been investigated by the UV/vis-spectrophotometric, magnetic, and electrochemical method. The two or three energy absorption bands are observed by the spectra of these complexes. The magnitude of crystal field splitting energy, the spin pairing energy and bond strength was obtained from the spectra of the complexes. These are found to be delocalization, low-spin state, and strong bonding strength. The magnetic dipolemoment are found to be paramagnetic and diamagnetic complexes. The redox reaction processes of complexes were investigated by cyclic voltammetry in aprotic media. As a result the redox reaction proceses of Nb-C complex was couple-single reaction with diffusion and reaction current one electron process, and also Mo-C complex was couple-single reaction with reaction current of one electron process.

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A Study on the Electronic Properties and Redox Reaction of Europium(Ⅲ) Complexes in Aprotic Solvent (반 양성자성 용매속에서 Europium(Ⅲ) 착물에 대한 전자적 성질과 산화 · 환원 반응에 관한 연구)

  • Choe, Chil Nam;Son, Hyo Youl;Kim, Se Bong
    • Journal of the Korean Chemical Society
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    • v.40 no.1
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    • pp.65-71
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    • 1996
  • The chemical behaviour of the Eu(Ⅲ) complexes with organic ligands(tris[3-(trifluoromethylhydroxymethylene-camphorato)]) and tris[3-heptafluoropropylhydroxymethylene-camphorato)] has been investigated by the UV/vis-spectrophotometric, magnetic, and electrochemcial methods. The two or three energy absorption bands are observed by the spectra of these complexes. The magnitude of crystal field splitting energy, the spin pair energy and strength were obtained from the spectra of the complexes. These complexes are found to be delocalization, low-spin state, and strong bonding strenth of electron configuration. The magnetic dipolemoment are found to be diamagnetic. The redox reaction processes of complexes were investigated by cyclic voltammetry in aprotic solvent. The redox reaction processes of complexes are turned out to be single or double reaction with respect to one electron diffusion current.

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Semiempirical Calculations of Hyperpolarizabilities for Quinoline Derivatives (Quinoline계 분자의 초분극률에 관한 반경험적 계산)

  • Ryu Ungsik;Choi Donghoon;Kim Nakjoong;Lee Yoon Sup
    • Journal of the Korean Chemical Society
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    • v.37 no.1
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    • pp.62-67
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    • 1993
  • The microscopic origin of nonlinear optical properties of quinoline derivatives have been investigated theoretically using MOPAC-AM1 method. In order to prepare promising nonlinear optical active polymers of polyquinoline derivatives, the optimized positions of strong electron donor and electron acceptor are determined in the heterocyclic ring for the energetically favorable structures. For each compound, the effect of the substituted positions on the microscopic nonlinear coefficients were investigated. Polyquinoline was already evaluated to have outstanding physical and mechanical properties so that its monomeric analogues were designed and synthesized for developing new second and third order nonlinear optical main chain polymers. Using the MOPAC-AM1 method, properties calculated include the intrinsic ground-state dipole moments, the polarizabilities, first and second hyperpolarizabilities under the condition of finite-field $(\omega$ = 0).

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Variations of Complex Permittivity due to Water Content and Heavy Metal Contamination (함수비와 중금속 오염도에 따른 유전상수의 변화)

  • Oh Myoun-Hak;Kim Yong-Sung;Yoo Dong-Ju;Park Jun-Boum
    • Journal of the Korean Geotechnical Society
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    • v.21 no.5
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    • pp.231-241
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    • 2005
  • Laboratory experiments were performed to examine the effects of water content and to see if permittivity had sufficient sensitivity to identify subsurface contamination. Both real and imaginary permittivities of unsaturated sand were strongly governed by the volumetric water content. Especially, a linear relationship between real permittivity and volumetric water content was derived at high frequencies (MHz ranges). Heavy metals in pore fluid result in significant increases in the effective imaginary permittivity, due to ionic conduction, but decreases in the real permittivity arises due to the decreased orientational polarization of water molecules caused by hydration of ions. Clear increase in the effective imaginary permittivity with heavy metal concentration was found to be valuable in the application of electrical methods for detecting heavy metals in the subsurface. However, because the permittivity is primarily dependent on the volumetric water content of soil, pre-evaluation on the volumetric water content is required.