천이금속 표면에서의 수소의 동력학 : 수소의 화학 흡착, 방출, 확산에 관하여

손기수,박동수,최상돈,김석환,김영주 慶北大學校 物理化學硏究所 1986 硏究論文集 Vol.7 No.-

S.M. Ko, L.D. Schmidt 등에 의하여 제시된 표면의 bulk내의 원자, 진공 근처 표면에서의 분자의 존재, 그리고 T. Engel, U. Kuipers 등에 의해서 제시된 진공과 bulk 사이에서의 분자와 원자간의 상호 변환 가설을 합쳐 진공과 접한 표면의 단 원자층에 화학흡수층을 설정하여 새로운 model을 만들었고, 이 model에 의하여 표면과 bulk 및 진공 사이에 일어나는 모든 과정 즉 표면과 bulk 사이의 difussion과 adsorption, 화학 흡수층에서 분자가 dissociation 과정을 거쳐 표면에 adsorption 되거나, recombination 과정을 거쳐 분자로 desorption 하는 과정등을 모두 설명할 수 있는 결과를 얻었다. 나아가서 평형 상태하의 표면 fraction과 화학 흡수층내의 분자의 시간분포, desorption하는 분자들의 시간 분포함수를 얻었다. 온도에 대해 peak amplitude와 log(θ/1-θ)의 값을 얻어서 실험치와 비교했으며, 수소원자의 desorption fraction을 얻었다. Proposing a new model which includes two states model and chemisorption layer right above the surface atomic layer which interrelates the atoms in bulk and the molecules in vacuum, the diffusion from the surface to bulk, adsorption on surface from chemisorption layer and desorption from chemisorption layer are explained. We also get the distribution of molecules versus time at the chemisorption layer, log(θ/1-θ), and atomic peak amplitude on surface versus the reciprocal temperature on equilibrium condition. These results are turned out to be good results. Furthermore by the use of above results, we derive the desorbing fraction as a linear function of inverse temperature.

산성수욕액에서 cis-aquo-bis(ethylenediamine)cobalt(Ⅲ) 착이온의 평형 및 착이온과 oxalate 이온간의 치환반응에 미치는 압력영향

박유철,이동철 慶北大學校 物理化學硏究所 1984 硏究論文集 Vol.5 No.-

The chemical equilibrium of cis-aquo-bis(ethylenediamine)cobalt(Ⅲ) complex ion and the kinetics of nucleophilic substitution reaction between the complex and oxalate ions have been spectrophotometrically investigated in a aqueous solution. Measurements of the optical density at wave lengths 490, 510 and 520 nm were carried out to determine the values of the equilibrium constants for the reactions: 〔Co(en)_2(H_2O)_2〕^3+ ⇔ 〔Co(en)_2(OH)(H_2O)〕^2+ + H^+; K_1 〔Co(en)_2(OH)(H_2O)〕^2+ ⇔ 〔Co(en)_2(OH)_2〕^+ + H^+; K_2 At 20℃ and in sodium nitrate media of unit ionic strength the equilibrium constants for these reactions, K_1 and K_2 were 7.36×10 exp(-6) and 3.81×10 exp(-10) respectively. The anation reaction between complex and oxalate ions studied as a function of total oxalate ion concentrations, 〔Ox〕_T were carried out at a various pressure (1-1000bar) and 60℃. By analysis of pseudo-first ordor rate constants observed as 〔Ox〕_T, it was found that the change of volume in the precess ion-pair formation, ΔV_5 is 8.3㎤/mole and that in the precess of rate determining step, ΔV_a^≠=5.7㎤/mole. In addition, the rate law of anation reaction in a wide range of pH was described. And by the change of volume determined the mechanism of anation was discussed.

아세톤-물혼합용매에서 trans-[Co(en)_2Cl_2]^+ 및 trans-[Co(1,3-pn)_2Cl_2]^+ 이온의 가용매 분해 반응에 미치는 압력과 용매조성의 영향

朴裕哲,卞鍾轍,金京美,趙靈濟 慶北大學校 物理化學硏究所 1985 硏究論文集 Vol.6 No.-

The rates of solvolysis of trans-[Co(en)_2Cl_2]^+ and trans-[Co(1,3-pn)_2Cl_2]^+, in which en and 1,3-pn are ethylenediamine and 1,3-propylenediamine resepectively, have been investigated using conductometric and spectrophotometric methods at various pressures up to 2,000 bar in acetone-water mixture. The activation volumes obtained from the pressure effect on rate constants were small and positive values in both complexes of trans-[Co(en)_2Cl_2]^+ and trans-[Co(1,3-pn)_2Cl_2]^+. These results are discussed in terms of dissociative mechanism (S_NI) for the solvolysis of both complexes. The importance of solvent composition on the reaction is further confirmed by application of a free energy cycle. It is concluded from the free energy cycle that the effect of solvation of transition state in the solvolysis of both complexes is more dominant than that of initial state. In addition to that, it is shown that the character of S_NI is further increased with increasing the content of acetone.

β-phenylethyl P-Bromobenzenesulfonate와 피리딘과의 고압반응에 관한 반응속도론적 연구

呂壽東,朴鍾煥 慶北大學校 物理化學硏究所 1984 硏究論文集 Vol.5 No.-

Recently, Kinetic studies of the reaction of benzylbenzenesulfonate with pyridine in acetone were carried out by the electric conductivity method under 1 to 2,000 bars at 20 to 40℃. From the activation enthalpy, activation entropy and activation volume, it was found that this reaction precedes via the S_N2 reaction mechanism in which the rate of the reaction was determined by C…N bond formation at the transition state.

Study of Metal and Semiconductor Surfaces using Field Ion Microscopy

Park, Tong Soo,Sohn, K. S.,Lee, W. S.,Chung, C. I. 慶北大學校 物理化學硏究所 1986 硏究論文集 Vol.7 No.-

A versatile metal Field Ion Microscope was designed and constructed. It features an axial feedthrough planetary drive for contacting the tip. The sueface of the tip can be coated with other elements in situ for the interface study. We have developed very effecitve method of preparing specimen tips. The image on 3" diameter screen is intensified by a microchannel plate. The optimum operating field strengths were ranged from 2×10 exp(8) volts to 4.5×10 exp(8) volts/㎝, while the magnification can be varied up to 5×10 exp(6) with the resolution of better than 2.75Å. The surface atoms of successive layer were cleaved by the pulse field evaporation. FIM images of tungsten, molybdenum, gold coated metals and tungsten silicides were observed and analysed. This is the first FIM in Korea.

Pressure and Oxalate Ion Effects on Anation of cis-Diaquobis-(ethylenediamine)cobalt(Ⅲ) with Oxalate Ion in Acidic Aqueous Solution

Park, Yu-Chul,Lee, Dong-Chul 慶北大學校 物理化學硏究所 1985 硏究論文集 Vol.6 No.-

0.5M HNO_3 수용액에서 cis〔Co(en)_2(H_2O)_2〕^3+와 oxalate 이온간의 치환반응속도를 oxalate 이온 농도 및 압력에 따라 분광광도법을 이용하여 측정하였다. 60℃에서 얻은 활성화체적(ΔV^*_obs)은 +9.2㎤/mole이었고, 압력에 거의 영향을 받지 않았다. ΔV^*_obs는 interchange 단계에서 일어나는 체적변화(ΔV^*_a=+9.6㎤/mole)와 유사하였다. ΔV^*_obs는 주로 ΔV_a^*와 반응물질의 이온쌍 형성 과정에서 일어나는 체적변화(ΔV_QIP)로 구성되므로 ΔV^*_obs에 대한 ΔV_QIP의 영향을 무시할 수 있었다. ΔV^*_obs, ΔV_a^* 및 ΔV_QIP를 각각 고찰하여 반응메카니즘이 I_d 과정에 따라 진행됨을 확인하였다.

A Singlet Oxygen Trapping Agent

Park, Y-T,Hwang, J-U 慶北大學校 物理化學硏究所 1985 硏究論文集 Vol.6 No.-

빌리루빈과 옥소디피로메텐들의 광산소화 분해 반응속도를 측정하던중 옥소디피로메텐들이 디페닐이소벤조퓨란보다 좋은 단일상태 산소의 트랩제라는 사실을 알게 되었다. 빌리루빈과 그 모델물질인 옥소디피로메텐들은 아주 빠른 속도로 단일상태 산소와 반응하거나 궨칭하였다. 한 새로운 옥소디피로메텐이 간단한 방법으로 합성되었다. Measuring the reaction rate of bilirubin and oxodipyrromethenes with signlet oxygen, we have found oxodipyrromethenes to be better singlet oxygen trapping agents than diphenyl isobenzofuran, the best such agent known so far. The photooxygenation rates of bilirubin and the model compounds, oxodipyrromethenes approached the diffusion control threshold. A new oxodipyrromethene is synthesized.

Energy Bands and Electronic Structure of (111) Mo Surface

Park, T.S.,Sohn, Ki-Soo 慶北大學校 物理化學硏究所 1981 硏究論文集 Vol.1-2 No.-

We have performed a tight-binding calculations of the energy bands of 40 atomic layers (lll) molybdenum thin slab. 24 Hamiltonian matrix parameters were obtained by fitting the bulk energy bands which were claculated by I. Petroff et al.. Energy bands were calculated at 49 points in the irreducible (1/12) two-dimensional Brillouin zone. Planar and total densities of states were obtained and compared with that of (lll) faces of iron.

Molybdenum, Niobium 表面特性에 關한 硏究 (Ⅰ) : Ni, Nb, Zr 表面과 酸素와의 相互作用 및 Nb-1% Zr, Nb-5% Zr 合金의 表面分晶 Interaction of oxygen with Ni, Nb and Zr Surfaces and Surface Segregation of Nb-1%Zr and Nb-5% Zr Binary Alloys

朴東秀,孫基洙,金裕榮,李元植 慶北大學校 物理化學硏究所 1981 硏究論文集 Vol.1-2 No.-

Interaction of oxygen with single crystal nickel, polycrystalline niobium and zirconium surfaces, and surface segregation of Nb-Zr(1%) and Nb-Zr(5%) were studied using Auger Electron Spectroscopy. The oxidation rate of Ni was parabolic while that of Zr was cubic. Beside O and C, S was also detected as the dominant impurity of nickel. Sergregation of sulfur to the nickel surface occured at temperature as low as 500℃, hence the segregation of S was limited to a few monolayers near the surface. Segregation of oxigen and zirconium to the Nb-Zr(1%) and Nb-Zr(5%) surfaces occured with the maximum at temperature around 1400℃ while segregation of carbon to these surfaces occured at temperature as low as 1000℃. It was revealed that when surfaces were cooled down to the room temperataytre O/Nb and Zr/Nb for Nb-Zr(5%) were many fold greaterthan for Nb-Zr(1%), in contrary, the situation became reverse when surfaces were spuctered in Ar(10^-2torr). The heat of segregation of zirconium to the surfaces of Nb-Zr(1%) and Nb-Zr(5%) was determined as -0.86KJ/mol. and -1.09KJ/mol. respectively.

Si-Schottky障壁型의 大陽電池 製作에 관한 硏究

李相潤,羅炳旭,朴德圭,李鍾德,金奎用,玄東杰,禹洪,盧景錫 慶北大學校 物理化學硏究所 1981 硏究論文集 Vol.1-2 No.-

The characteristics of these Si-schottky barrier type and Heterojunction type solar cells are as follows; 1. SnO_2/n-Si Heterojunction Solar Cells Fabricated by Spray Pyrolysis Method SnO_2 film were deposited on the (100) or (111) surface of Si single crystal by the spray pyrolysis method. The best SnO_2/n-Si solar cell has a good performance, with an open-circult voltage: Voc.=0.45V, short circuit current: Isc.=35.5㎃, fill factor: FF.=0.64, and conversion efficiency: η=10.2% under 98㎽/㎠ irradiation of AMl. The spray pyrolysis described in this paper is simple and suitable for mass production. One possibility for cost reduction lies in this method of junction fabrication, and the idea of simply deposited SnO_2/n-Si junction is, at first sight, very attractive. Hence the SnO_2/n-Si Solar Cell and the effectiveness of this method may be of great value in some future production of low-cost solar cells. 2. In_2O_3: Sn Heterojunction Solar Cells Fabricated by Spray Pyrolitic Method Highly conductive and transparent thin films of In_2O_3: Sn (ITO) are fabricated by spray pyrolytic method. The parameters of these thin films are as follows: resistivity ρ = 1.5×10 exp (-3) Ω·㎝, carrier concentration n = 7.5×10 exp (19) cm^-3, mobility μ = 55.5 ㎠/V·sec and transmission 85-90% over visible and long wave-length region. These thin films have simple cubic system with lattice constant 10.2Å. In_2O_3: Sn/n-Si heterojunction solar cells are fabricated, depositing In_2O_3: Sn (ITO) thin films on n-Si substrates with orientation(100) and resistively 2-3Ω, ㎝ by spray pyrolitic method. Under AMl sunlight simulator, the parameters of the excellent cell obtained has open-circuit voltage Voc=0.52V, short-circuit current I_sc=39.0㎃, fill factor: F.F=0.60 and conversion efficiencyη=12.1%. 3. Al/p-Si MOS Solar Cells Fabricated by Vacuum Evaporation Method Al/p-Si MOS solar cells, consisting of Al on P-tupe silicon with a thin interfacial layer of SiO_2 have been found to have good light conversion efficiency for solar radiation. The effects of the oxide layer thickness between metal and substrate were investigated. Under AMl simulated sunlight illumination the best cell has open circuit voltage Voc=0.50V, short-circuit current I_sc=26.3㎃/㎠, fill-factor FF=0.70 and conversion efficiency η=9.2%. 4. Cr-Cu/P-Si MOS Solar Cells Fabricated by Vacuum Evaporation Method Cr-Cu/p-Si MOS Solar cells, consisting of Cr-Cu on p-type silicon with a thin interfacial layer of SiO_2 have been found to have good light conversion efficiency for solar radiation. The effects of the oxide layer thickness between metal and substrate were investigated. Under AMl simulated sunlight illumination the best cell has open circuit voltage Voc=0.49V, short-circuit current I_sc=26.4㎃, fill-factor: FF=0.72 and conversion efficiency η=9.3%.