• 전기화학회지
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• 제15권3호
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• pp.165-171
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• 2012

본 연구에서는 전기화학계에서 중요한 다중전자의 이동이 수반되는 전극 반응에 대하여 순환전위법의 특성곡선을 모델링하여, MATLAB 프로그램으로 구현하였다. 전극주변의 전기화학 물질전달계에 대하여 반무한 확산모델의 경계조건을 설정하였고, Fick의 농도방정식은 유한차분법으로 전개하여 수치해를 구하였고, Butler-Volmer 식으로부터 계산된 농도값을 전류의 값으로 전환하였다. 본 연구에서 구현된 수치해는 기존의 실험치들과 합리적으로 설명하고 있었으며, 이를 근거로 다중전자 전기화학 반응계에서 반응메카니즘에 대한 전극반응속도 상수와 CV 주사속도 영향을 효과적으로 해석할 수 있었다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 영호남 합동 학술대회 및 춘계학술대회 논문집 센서 박막 기술교육
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• pp.63-64
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• 2006

본 연구에서는 광에너지를 화학적인 에너지로 변환할 때, 디바이스의 전하전달 매개를 위한 electron transfer mediator로서 널리 이용되는 Viologen이 자기조립화된 수정진동자률 전기화학법의 하나인 순환전압전류법(Cyclic Voltammetry)을 이용하여 산화 환원 반응 (redox reaction) 특성과 주사속도와 피크전류와의 상관관계를 분석하였다. 먼저 수정진동자를 친수 처리한 후, 메탄올 용액과 아세토니트릴 용액을 섞은 용매에 Viologen 분자를 자기조립 (self-assembly)하여, 전해질 용액의 농도 변화에 따른 산화 환원반응 특성과 피크전류의 값을 측정하였다 주사 속도를 2 배씩 증가하여 피크전류와의 상관관계를 조사한 결과, 선형적인 증가를 보였으며, 이를 통해 가역적인 반응(reversible reaction)이 일어났음을 확인할 수 있었다. 또한, 산화 환원 반응과 동시에 측정된 수정진동자의 공진 주파수(resonant frequency) 변화로부터 전하이동(charge transfer) 특성에 의해 반응에 참가한 이온의 질량을 알 수 있었다.

• Bulletin of the Korean Chemical Society
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• 제20권10호
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• pp.1181-1185
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• 1999

The reaction of FeC5H5+ ion with ferrocene molecule is investigated using FT-ICR mass spectrometry. FeC5H5+ ions are generated by dissociative ionization of ferrocenes using an electron beam. The reaction gives rise to the formation of the adduct ion, Fe2(C5H5)3+, in competition with charge transfer reaction leading to the formation of ferrocene molecular ion, Fe(C5H5)2+·. The branching ratio of the adduct ion increases as the internal energy of the reactant ion decreases and correspondingly the branching ratio for the charge transfer reaction product decreases. The observed rate of the addition reaction channel is slower than that of the charge transfer reaction. The observation of the stable adduct ions in the low-pressure ICR cell is attributed to the radiative cooling of the activated ion-molecule complex. The mechanism of the reaction is presented to account for the observed experimental results.

• Bulletin of the Korean Chemical Society
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• 제28권9호
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• pp.1523-1530
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• 2007

The first reduction peak of the cyclic voltammogram (CV) for sulfur reduction in dimethyl sulfoxide has been studied using time resolved Fourier transform electrochemical impedance spectroscopic (FTEIS) analysis of small potential step chronoamperometric currents. The FTEIS analysis results reveal that the impedance signals obtained during short potential steps can be resolved into electron transfer reactions of two different time constants in a high frequency region. The FTEIS method provides snap shots of impedance profiles during an earlier phase of the reaction, leading to time resolved EIS measurements. Our results obtained by the FTEIS analysis are consistent with a series of electron transfer and chemical equilibrium steps of a complex reaction, making up an ECE (electrochemical-chemical-electrochemical) mechanism postulated from the results of computer simulation.

• 분석과학
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• 제8권4호
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• pp.481-486
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• 1995

Quenching experiments by photoinduced electron transfer between a charged donor and a neutral acceptor were carried out in acetonitrile, dichloromethane and mixed solvents of acetonitrile and dichloromethane. Tris(2, 2'-bipyridine) ruthenium(II) ($[Ru(bpy)_3]^{2+}$) which has 2+ charge and dicyanobis (2, 2'-bipyridine) ruthenium(II) ($Ru(bpy)_2(CN)_2$) which has no charge were used as electron donors, and a series of tris(${\beta}$-diketonato) ruthenium (III) was used as acceptor. In dichloromethane, $[Ru(bpy)_3]^{2+}$ and its counter ions ($ClO{_4}^-$) form ion pair. In the estimate of ${\Delta}G$ of electron transfer, the electrostatic potential between counter ions and product ion pair produced by electron transfer must be taken into account. A similar effect of counter ions was found in mixed solvents of 10, 30, 50, 70 and 90% acetonitrile ratio in volume. The effect of counter ion on ${\Delta}G$ became smaller with the increase in acetonitrile ratio. The result in mixed solvents suggests that $[Ru(bpy)_3]^{2+}$ and its counter ions form ion pair even in 90% acetonitrile solution.

• 대한화학회지
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• 제38권8호
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• pp.598-602
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• 1994

이핵착물 $(NC)_5FeII-L-CoIII(NH_3)_5$ 분자내에서의 광유발 전자이동반응을 정류상태 광분해 실험으로 조사하여 속도상수를 결정하고 다리리간드 L의 종류에 따른 영향을 고찰하였다. 금속 결합자리 사이에 콘쥬게이션이 유지되는 BP, PHEN, DAP 리간드는 klight가 약 $3{\times}10^{-2} sec^{-1}$, 양자수율이 상한값인 1이였으며 콘쥬게이션이 유지되지 못하는 BPEA리간드인 klight가 약 $2{\times}10^{-4} sec^{-1}$, 양자수율이 0.03으로 측정되었다. 이로부터 광유발 전자이동반응이 전하이동 들뜬 상태 MLCT*를 거치는 "화학적 메카니즘"인 것으로 증명하였다.

• Bulletin of the Korean Chemical Society
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• 제20권8호
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• pp.935-938
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• 1999

Reactivity and reaction mechanism for the reactions of 1,1'-(azodicarbonyl) dipiperidine with triphenylphosphines are investigated using kinetic method. The cation radical, Ph3P and the anion radical, -N-N - are produced during the course of the reaction. The cation radical is formed by the transfer of an electron from phosphorus to the nitrogen atom. The anion radical is formed by the addition of the one electron to the azo rad-ical. The rate constants are decreased by electron withdrawing groups while they are increased by electron donating groups present in triphenylphosphine. The electron density increases on nitrogen, while positive charge is developed on phosphorus in the transition state.

• Biotechnology and Bioprocess Engineering:BBE
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• 제10권1호
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• pp.47-51
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• 2005

The bioelectrochemical reduction of nitrate in the presence of various mediators including methyl viologen and azure A was studied using a 3-electrode voltammetric system. The catalytic potential for the reduction of the mediators was observed in the reactor, which for methyl viologen and azure A were -0.74 V and -0.32 V, respectively, with respect to the potential of Ag/AgCl reference electrode. This potential was then applied to a working electrode to reduce each mediator for enzymatic nitrate reduction. Nitrite, the product of the reaction, was measured to observe the enzymatic nitrate reduction in the reaction media. Methyl viologen was observed as the most efficient mediator among those tested, while azure A showed the highest electron efficiency at the intrinsic reduction potential when the mediated enzyme reactions were carried out with the freely solubilized mediator. The electron transfer of azure A with respect to time was due to the adhesion of azure A to the hydrophilic surface during the reduction. In addition, the use of the adsorbed mediator on conductive activated carbon was proposed to inhibit the change in the electron transfer rate during the reaction by maintaining a constant mediator concentration and active surface area of the electrode. Azure A showed better than nitrite formation than methyl viologen when used with activated carbon.

• 한국광과학회:학술대회논문집
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• 한국광과학회 1999년도 학술대회지
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• pp.61-61
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• 1999

• Journal of Photoscience
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• 제5권1호
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• pp.23-26
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• 1998

Irradiation of diphenylbutadiyne (DPB) in methanol with 9,10-dicyanoanthracene (DCA) yields four methanol adducts, two more than the products obtained in the absence of DCA. Laser flash photolysis studies indicate the reaction to proceed through a photoinduced electron transfer mechanism involving DPB cation radical and DCA anion radical.