• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 하계학술대회 논문집 C
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• pp.1019-1021
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• 1995

Light induced degradation of hydrogenated amorphous silicon(a-Si:H) are related to the number of weak dangling bonds which are thought to be responsible for the Staebler-Wronski effects, and caused the many photoelectric problems in applications of thin film transistors and solar cell, etc. In this paper, we deposited fluorinated amorphous silicon films(a-Si:H;F) with $SiH_4$ and $SiF_4$ gas mixture and investigated the effects of fluorine atoms on the evoluations of the crystallinity and improvements of light instability. We have found that micro-crystallinity produced in a-SI:H;F films and marked maximum value of 22% at the flow rate of $SiH_4:SiF_4$=2:10 sccm by UV spectrophotometer measurement, while n-Si:H film deposited with only $SiH_4$ gas showed no crystallinity. Light-induced degradation property of a-Si:H;F films is also improved which is mainly due to the etching effects of fluorine atoms on the weak Si-Si bonds and unstable hydrogen bonds. It is considered that involving fluorine atoms in a-Si:H films may contribute to the suppression of light-induced degradation and evolution of micro-crystallinity.

• 한국결정성장학회지
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• 제13권5호
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• pp.211-216
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• 2003

The $Cu[SO_3(CH_2)_4SO_3$］ㆍ$4H_2O$ compound was synthesized. The three-dimensional structure of $Cu[SO_3(CH_2)_4SO_3$］ㆍ$4H_2O$ compound was determined. The copper atom is bridged by 4 oxygen atoms of 4 water molecules and 2 oxygen atoms of butanedisulfonate. The butyl chain in the plane of four copper atoms is oriented parallel and perpendicular to the one of plane axis, alternatively. Magnetic data indicate that this compound behaves a typical paramagnetic.

• 분석과학
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• 제20권4호
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• pp.355-360
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• 2007

The title complex, $(C_3H_{12}N_2)[\{Cd(H_2O)(C_6H_5O_7)\}_2]{\cdot}6H_2O$, I, has been prepared and its structure characterized by FT-IR, EDS, elemental analysis, ICP-AES, and X-ray single crystallography. It is triclinic system, $P{\bar{1}}$ space group with a = 10.236(2), b = 11.318(2), c = $13.198(2){\AA}$, ${\alpha}=77.95(1)^{\circ}$, ${\beta}=68.10(1)^{\circ}$, ${\gamma}=78.12(1)^{\circ}$, V = $1373.5(3){\AA}^3$, Z = 2. Complex I has constituted by protonated 1,3-diaminopropane cations, citrate coordinated cadmium(II) anions, and free water molecules. The central cadmium atoms have a capped trigonal prism geometry by seven coordination with six oxygen atoms of three different citrate ligands and one water molecule. Citrate ligands are bridged to three different cadmium atoms. Each cadmium atom is linked by carboxylate and hydroxyl groups of citrate ligand to construct an one-dimensional ladder-type assembly structure. The polymeric crystal structure is stabilized by three-dimensional networks of the intermolecular O-H${\cdots}$O and N-H${\cdots}$O hydrogen-bonding interaction.

• Bulletin of the Korean Chemical Society
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• 제25권6호
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• pp.852-858
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• 2004

Crystal structures of lanthanide complexes with NTA (NTA = nitrilotriacetate) are reported. The complexes of $[Ln(NTA)_2{\cdot}H_2O]^{3-}$ (Ln = Sm, Eu, Gd, Tb and Ho) crystallize in the orthorhombic space group Pccn. In the structures, the trivalent lanthanide ions are completely encapsulated via coordination to the two nitrogen atoms and the six carboxylate oxygen atoms of the two NTA ligands, and one water oxygen atoms. The complexes form a slightly distorted capped-square-antiprism polyhedron. Of the complexes, $[Eu(NTA)_2{\codt}H_2O]^{3-}$,\;[Tb(NTA)_2{\cdot}H_2O]^{3-}\;and\;[Dy(NTA)_2{\cdot}H_2O]^{3-}$ excited at the 325 He-Cd line produce very characteristic luminescence features, arising mostly from the f ${\to}$ f transitions. The absolute quantum yields of these complexes are determined at room temperature. Surprisingly, the $[Dy(NTA)_2{\cdot}H_2O]^{3-}$ complex is more luminescent than the $[Eu(NTA)_2{\cdot}H_2O]^{3-}\;and\;[Tb(NTA)_2{\cdot}H_2O]^{3-}$ complexes.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.210.1-210.1
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• 2014

The hexagonal boron nitride (h-BN) sheet, a 2D material like graphene sheet, is comprised of boron and nitrogen atoms. Similar to graphene, h-BN sheet has attractive mechanical properties while it has a wide band gap unlike graphene. Recently, many experimental groups studied the growth of single BN layer by chemical vapor deposition (CVD) method on the copper substrate. To study the initial stage of h-BN growth on the copper surface, we have performed density functional theory calculations. We investigate several adsorption sites of a boron or nitride atom on the Cu surfaces. Then, by increasing the number of adsorbed B and N atoms, we study formation behaviors of the BN flakes on the surface. Several types of BN flakes atoms such as triangular, linear, and hexagonal shapes are considered on the copper surface. We find that the formation of the BN flake in triangular shape is most favorable on the surface. On the basis of the theoretical results, we discuss the growth mechanism of h-BN layer on the copper surfaces in terms of its shapes in the initial stage of growth.

• Bulletin of the Korean Chemical Society
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• 제33권6호
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• pp.2017-2022
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• 2012

Three isostructural lanthanide coordination polymers, $[Ln(L)_3(H_2O)_2](H_2O)_3$ {Ln = Eu (1), Tb (2), Gd (3); L = $trans$-3-(3-pyridyl)acrylate, (3-py)-CH=CH-COO}, were prepared from HL, lanthanide nitrate, and NaOH in $H_2O$ by microwave heating. In all coordination polymers, the metal is bonded to eight oxygen atoms, and all pyridyl nitrogen atoms do not coordinate to the metals. All polymers have a 1-D loop-connected chain structure. The hydrogen atoms in the aqua ligands and lattice water molecules all participate in the hydrogen bonds of the O-$H{\cdots}O$ or O-$H{\cdots}N$ type. The hydrogen bonds connect the 1-D chains to create a 2-D network. Polymer 1 exhibited red luminescence in the solid state at room temperature.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1998년도 하계종합학술대회논문집
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• pp.437-440
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• 1998

We studied phosphorus doping effect on the epitaxial growth of $Si_{1-x}Ge_{x}$ film with high Ge fraction on Si substates at 550.deg. C by LPCVD. In a low $Ph_{3}$ partial pressure region such as below 1.25 mPa, the phosphorus dopant concentration increased linearly with increasing $PH_{3}$ partial pressure while the deposition rate and the Ge fraction were constant. In a higher $PH_{3}$ partial pressure region, the phosphorus dopant concentration and the deposition rate decreased, while the Ge fraction slightly increased. The deposition arate and the Ge fraction increased with increasing $GeH_{4}$ partial pressure while the phophours dopant concentration decreased. But the increasing rate of Ge fraction with incrasing $PH_{3}$ partial pressure was reduced at a high $GeH_{4}$ partial pressure. According to test results, it suggests that high surface coverage of phosphorus atoms suppress both the $SiH_{4}$ adsorption/reasction and the $GeH_{4}$ adsorption/reaction on the surfaces, and the effect is more stronger on $SiH_{4}$ than on $GeH_{4}$. In a higher $PH_{3}$ partial pressure region, the epitaxial growth is largely controlled by surface coverage effect of phosphorus atoms. The phosphorus surface coverage was slimited at a high $GeH_{4}$ partial pressure because adsorbed Ge atoms effectively suppresses the adsorption of phosphorus atoms.

• 한국광학회:학술대회논문집
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• 한국광학회 2000년도 하계학술발표회
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• pp.74-75
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• 2000

The past few decades have witnessed the development of very robust technique, known as magneto-optical trap(MOT), for cooling and trapping of neutral atoms using lasers and magnetic fields. This technique can easily produce cooled atoms to a temperature range of nano-kelvin $s^{(1)}$ . These laser cooled and trapped atoms have found applications in various fields, such as ultrahigh resolution spectroscopy, precision atomic clocks, very cold atomic collision physics, Bose-Einstein Condensation, the Atom laser, etc. Particularly, a few isolated atoms of very low temperature are needed in the cavity QED studies in the optical regime. One can obtain such atoms from a MOT using the atomic fountain technique. The widely used technique for atomic fountain is, first to cool and trap the neutral atoms in MOT. And then launch them in the vertical (1, 1, 1) direction with respect to cooling beams, using moving molasses technique. Recently, this technique combined with the cavity-QED has opened an active area of basic research. This way atoms can be strongly coupled to the optical radiation in the cavity and leads to various new effects. Trapping of single atom after separating it from MOT in the high Q-optical cavity is actively initiated presentl $y^{(2.3)}$. This will help to sharpen our understanding of atom-photon interaction at quantum level and may lead to the development of single-atom laser. Our efforts to develop an $^{85}$ Rb-atomic fountain is in progress. (omitted)

• 대한화학회지
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• 제23권1호
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• pp.20-29
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• 1979

과산화수소와 에탄의 integral rotation barrier의 원천적 요인을 결합 공간과 반결합 공간의 개념을 이용하여 연구하였다. internal rotation barrier는, 중심 원자의 존재로 인하여 천이밀도가 중심 원자가 없을 때보다 더 많이 반결합 공간으로 쏠림에 기인 함을 밝혔다. 이러한 천이밀도의 쏠림은 강한 O-H (또는 C-H) 결합에 의하여 내부 회전에 따른 전자밀도의 변화가 적어지는 것으로 설명할 수 있음을 보였다.

• Bulletin of the Korean Chemical Society
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• 제29권1호
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• pp.177-180
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• 2008

Laser induced fluorescence studies of hydrogen atom using four wave mixing technique are reported for the photodissociation of CH4 and its isotopomers at Lya (121.6 nm). The source of dissociating and probe radiation is one and the same (delay time??20 nsec). The average translational energy of ejected hydrogen atoms (50 Kcal/mol) reveals that CH4 + hn??CH3 + H(2S) and CH4 + hn??CH2(a1A1) + H2(1Sg) are the main dissociation processes. The absolute quantum yield for CH4 and CD4 are the same, FH(CH4) = FD(CD4) = 0.31 0.05. If one divides the experimental H/D ratios from the isotopomers CH3D, CH2D2, CHD3 by the isotopic H/D ratios, a value 2 is obtained in all three cases. Overall, the heavier D atoms are more likely than the H atoms to remain attached to the carbon atom.