• Journal of the Korean Chemical Society
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• 제37권3호
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• pp.335-343
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• 1993

The maximum absorption wavelengths of charge-transfer complexes of naphthalene, ${\alpha}-and{\beta}-methyl$ naphthalene and 1,2-, 2,3-and 2,6-dimethyl naphthalene with chloranil have been measured with a UV spectrophotometer in ethylene chloride, methylene chloride, and chloroform at 10, 15, 20, and 25$^{\circ}C$. This absorption band was interpreted as the charge transfer band of a 1 : 1 molecular complex, and the maximum absorption wavelength was changed as a function of solvent and temperature. Their formation constants (K$_f$) were decreased with the polarity of solvent and the increase of temperature. Thus, the influences of solvent and temperature on the formation constant have been discussed as consideration of thermodynamic properties, and the electronic and steric effects of electron donors on formation constant have been also discussed.

• Bulletin of the Korean Chemical Society
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• 제15권6호
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• pp.465-468
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• 1994

The charge transfer compounds $(TTF)_4FeCl_3{\cdot}CH_3OH,\;(TTF)_4SbCl_4\;and\;(TTF)_5(SbBr_4)_2{\cdot}CH_3COCH_3$ were prepared from reactions of the TTF (tetrathiafulvalene) and metal halides. The compounds were characterized by spectroscopic (UV,IR, EPR and XPS) methods, magnetic susceptibility and electrical conductivity measurements. The d.c electrical conductivities of the pressed pellets are in the order of $10^{-1}-10^{-3} Scm^{-1}$, which lies in the range of semiconductor region at room temperature. It means that the partially ionized TTF has stacked in low-dimensional chain in each compound. Spectroscopic properties also indicate that TTF molecules are partially ionized and charge transfer has occurred from (TTF)n to Fe(III) center in $(TTF)_4FeCl_3{\cdot}CH_3OH$ whereas to the $-SbX_4^-$ entity in $(TTF)_4SbCl_4\;and\;(TTF)_5(SbBr_4)_2{\cdot}CH_3COCH_3$. The EPR g values are consistent with TTF radical formation and EPR linewidths suggest the delocalization of unpaired electrons along TTF stacks. A signal arised from metal (Fe and Sb) ions were not detected in EPR spectra, indicating that metal ion is in the diamagnetic state in each compound. The diamagnetic state was also examined by the magnetic susceptibility measurement. The magnetic properties reveal the significant interaction between the $TTF^+$ radical cations in the stacks. The oxidation state of metal ions was also investigated by XPS spectra.

• Korean Journal of Metals and Materials
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• 제47권10호
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• pp.644-651
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• 2009

The passivation (or deactivation) of a metal surface during oxide film formation has been quantitatively explored for a ferritic stainless steel by using dynamic electrochemical impedance spectroscopy (DEIS). For this purpose, the electrochemical impedance spectra were carefully examined as a function of applied potential in the active nose region of the potentiodynamic polarization curve, to separate the charge transfer resistance and oxide film resistance. From the discrepancy in the potential dependence between the experimental charge transfer resistance and the semi-empirically expected one, the degree of passivation could be quantitatively estimated. The sensitivity of passivation of the steel surface to anodic potential, which might be the measure of the quality of the oxide film formed under unit driving force or over-potential, decreased by 31% when 3.5 wt% NaCl was added to a 5 wt% $H_2SO_4$ solution.

• Korean Journal of Optics and Photonics
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• 제9권3호
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• pp.205-211
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• 1998

The MTF(modulation transfer function) measuring system with a linear CCD(charge coupled-device) was constructed to cvaluate a color CRT(catode ray tube). The measured MTF values were corrected by considering the spectral response and the pixel sizes of CCD. The effects of a spot size, video bandwidth, pitch of shadow mask holes, display luminance, and ambient illumination on image quality were studied. The uniformity of resolution and the contrast Ioss by ambient light of the color CRT monitor were measured, and the results were analyzed by MTFA(modulation threshold area).

• Journal of the Korean Applied Science and Technology
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• 제14권1호
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• pp.89-93
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• 1997

In this research, ultra-thin films of organic charge transfer complex were deposited on to ordinary microscope slide-glass subtrates with a Langmuir-Blodgett technique. ${\pi}$-A isotherm characteristics of these complex were studied in order to find optimum conditions of deposition by varying temperature of subphase, compression speed, and spreading amount. Transfer ratio of these films were studied during the process of deposition. The UV-visible absorbance spectra of LB films were measured to find state of deposition by varing layer number. The observed optimum conditions of surface, pressure, spreading amount, and dipping speed for depositing LB films(Y-type) were 38m/Nm, $150{\mu}l$ and 5mm/min, respectively. Since the tansfer ratio is close to 100%, the monolayer on the subphase seems to be well transferred to the solid substrate. The thickness of the film was well-controlled as the UV-vis absorbance of films were changed linear according to the number of layers.

• Bulletin of the Korean Chemical Society
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• 제14권6호
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• pp.704-708
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• 1993

The intramolecular charge transfer (ICT) phenomena of the photoexcited 2-biphenylcarboxylic acid (2BPCA) and 4-biphenylcarboxylic acid (4BPCA) have been investigated in some surfactant micellar solutions. The ICT emission of 4BPCA and 2BPCA in aqueous solution at sufficiently low pH (1-3) has been observed to be markedly quenched and blue-shifted upon addition of a cationic surfactant, cetyltrimethylammonium chloride (CTAC) in contrast to little change in anionic sodium dodecyl sulfate (SDS) and neutral Brij 35. An anionic emission band has been observed to be enhanced at expense of the ICT emission as a function of the concentration of CTAC. These results with the micellar effects on the fluorescence decay kinetics of 4BPCA suggest that formation of the ICT state of the excited acids is inhibited by CTAC-induced proton transfer as well as the decrease in the polarity and/or hydrogen-bonding ability of the micellar microenvironment entrapping the acids.

• Analytical Science and Technology
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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.

• Proceedings of the IEEK Conference
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• 대한전자공학회 1998년도 하계종합학술대회논문집
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• pp.863-866
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• 1998

In this paper two quick boosting charge pump circuits for high-speed EEPROM memory are proposed. In order to improve initial charge transfer efficiency, one uses weighted capacitors where each stage has different clock coupling capacitance, and the other uses a multi-path structure at the first stage. SPICE simulation results show that these charge pumps have improve drising-time characteristics, but their $V_{DD}$ mean currents are increased a little compared with conventioanl charge pumps. The rising time upt o 15V of the proposed charge pumps is 3 times faster than that of dickson's pump at the cost of 1.5 tiems more $V_{DD}$ mean current.rrent.

• The Journal of the Korea institute of electronic communication sciences
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• 제15권3호
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• pp.487-494
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• 2020

In this paper, we propose a current memory circuit design that reduces static power consumption and maximizes the advantages of current mode signal processing. The proposed current memory circuit minimizes the problem in which the current transfer error increases as the data transfer time increases due to clock-feedthrough and charge-injection of the existing current memory circuit. The proposed circuit is designed to insert a support MOS capacitor that maximizes the Miller effect in the current transfer structure capable of low-power operation. As a result, it shows the improved current transfer error according to the memory time. From the experimental results of the chip, manufactured with MagnaChip / SK Hynix 0.35 process, it was verified that the current transfer error, according to the memory time, reduced to 5% or less.

• Proceedings of the Korean Vacuum Society Conference
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• 한국진공학회 2011년도 제41회 하계 정기 학술대회 초록집
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• pp.68-69
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• 2011

The process of charge transfer at the interface between two semiconductors or between a metal and a semiconductor plays an important role in many areas of technology. The optimization of such devices requires a good theoretical description of the interfaces involved. This, in turn, has motivated detailed mechanistic studies of interfacial charge-transfer reactions at metal/organic, organic/organic, and organic/inorganic semiconductor heterojunctions. Charge recombination of photo-induced electron with redox species such as oxidized dyes or triiodide or cationic HTM (hole transporting materials) at the heterogeneous interface of $TiO_2$ is one of main loss factors in liquid junction DSSCs or solid-state DSSCs, respectively. Among the attempts to prevent recombination reactions such as insulating thin layer and lithium ions-doped hole transport materials and introduction of co-adsorbents, although co-adsorbents retard the recombination reactions as hydrophobic energy barriers, little attention has been focused on the anchoring processes. Molecular engineering of heterogeneous interfaces by employing several co-adsorbents with different properties altered the surface properties of $TiO_2$ electrodes, resulting to the improved power conversion efficiency and long-term stability of the DSSCs. In this talk, advantages of the coadsorbent-assisted sensitization of N719 in preparation of DSSCs will be discussed.