• Transactions on Electrical and Electronic Materials
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• 제4권1호
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• pp.1-6
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• 2003

We have studied the size confinement effect on the properties of melting-like transition of small icosahedral copper clusters using a classical molecular dynamics simulation based on a well fitted empirical potential. We investigated the caloric curves of icosahedron nanoclusters and the significant depression in the melting temperatures of the copper nanoclusters was compared with that of the bulk copper. A structural transitions from decahedral to icosahedral shapes were shown. As the cluster size increased, the melting temperature increased, and the latent heat increased but seem to be saturated. However, the specific heat was unrelated to the cluster size.

• Bulletin of the Korean Chemical Society
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• 제34권2호
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• pp.453-459
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• 2013

In phtosynthetic light harvesting complexes, the electronic transition energies of chlorophylls are influenced by the Coulombic interaction with nearby molecules. Variation of the interactions caused by structural inhomogeneity in biological environment results in a distribution of disordered electronic transition energies of chlorophylls. In order to provide a practical guide to predict qualitative tendency of such distribution, we model four porphyrin derivatives including chlorophyll a molecule interacting with an external positive charge and calculate their transition energies using the time dependent density functional method. It is found that ${\pi}-{\pi}^*$ transition energies of the molecules are generally blue-shifted by the charge because this stabilizes occupied molecular orbitals to a greater extent than unoccupied ones. Furthermore, new transitions in the visible region emerge as a result of the red-shift in energy of an unoccupied Mg orbital and it is suggested that light-induced electron transfer may occur from the tetrapyrrole ring to the central magnesium when the molecules are interacting with a positive charge.

• 한국진공학회지
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• 제12권S1호
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• pp.104-106
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• 2003

In this study, the electronic structures and physical properties of Ni$_2$MnGa alloy films and their dependence on the order-disorder structural transitions were investigated. The results show that the ordered films behave nearly the same as the bulk $Ni_2$MnGa alloy, including the martensitic transformation at 200 K. Unexpectedly, the disordering in $Ni_2$MnGa alloy films does not lead to any appreciable magnetic ordering down to 4 K. An annealing of the disordered films restores the ordered structure with an almost full recovery of the magnetic and the transport properties of the ordered $Ni_2$MnGa alloy films. A possible explanation of the disappearance of magnetic moment in the disordered film is given by using the ab initio first-principles electronic-structure calculations.

• Journal of Photoscience
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• 제3권1호
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• pp.43-47
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• 1996

The 77 K emission and excitation, and room-temperature UV-visible spectra of $\Lambda$-fac[Cr(L-ala)$_3$] (ala = alanine anion) have been measured. The ten electronic transitions due to spinallowed and spin-forbidden are assigned. With the observed electronic transition energies, ligand field optimizations have been performed to determine the bonding properties of L-alanine anion toward chromium(III). The angular overlap model (AOM) parameters obtained indicate that it is electron-donating ligand which has values of e$_{\sigma}O$, e$_{\pi}O$, and e$_{\sigma}N$ slightly lower than those of glycine anion (gly). It seem that the decrease of the ligand field properties is due to steric effect of extra methyl group and inductive effect of adjacent carbonyl group.

• 한국전기전자재료학회논문지
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• 제11권3호
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• pp.188-194
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• 1998

The GaSe:$Er^{3+}$(5mol%) single crystals grown by the Bridgman technique displayed a direct energy gap at 1.79 eV and an indirect energy gap of 1.62 eV at 300 ${\circ}^$K. Also an optical absorption peak by impurity was found at 6505 $cm^{-1}$. The peak identified the origin of the electronic transitions to be between the energy levels of $Er^{3+}$ ions.

• Transactions on Electrical and Electronic Materials
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• 제3권2호
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• pp.20-23
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• 2002

Temperature (T) dependence of the sheet resistance (R$\_$$\square$/) has been investigated an the c-axis oriented thin films of the (Bi2212/Bi2201) mixed crystal with different molar fractions. The R$\_$$\square$/-T superconducting characteristic deteriorated with reduction of the Bi2212 fraction, and almost disappears at 48 mol% where a superconductor-to-insulator transition too k place, with the resistance on the normal state, R$\_$N/, reaching 4.1 kΩka at 80 K. This R$\_$$\square$/ value is close to the universal quantum number, h/(2e)$_2$≡ 6.5 kΩ predicted by the Kosterlitz-Thouless (KT) transition theory. The R$\_$$\square$/-T characteristics of the 48 mol% thin film can be elucidated as a competitive process of KT transition brought about by charge or vortex in the two-dimensional layer structure.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 하계학술대회 논문집 Vol.4 No.1
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• pp.216-218
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• 2003

The Judd-Ofelt theory is becoming basis that induced of ligand field of electric dipole transitions of between 4f electic states. It is developed for the rare earth ions through judd and of ofelt. This theory be applicate success to the raer earth ions in solid, liquid and gas state. This paper reports a optical characteristices of Nd:glass by using the Judd-Ofelt Method.

• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2009년도 학술논문요약집
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• pp.257-258
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• 2009

• 대한전기학회논문지
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• 제31권11호
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• pp.141-145
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• 1982

Optical absorption properties of an orphous Se film due to interband electronic transitions are observed in the visible range by varying the folm thickness. Amorphous Se films were prepared by evaporation method. As the experimental results, it is found that optical energy gap is around 2.07(e V), and the optical constants depend on the film thickness, evaporation-deposition conditions, and incident photon energy.

• Bulletin of the Korean Chemical Society
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• 제17권10호
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• pp.882-885
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• 1996

The 6a10 and 6b10 vibronic bands in the 12A2-12B2 electronic transition of the emission spectra of the benzyl radical obtained using a high resolution Fourier transform spectrometer are rotationally analyzed. The observed rotational contours were fitted by computer simulated rotational contours, providing determination of the variations, ΔA, ΔB, and ΔC of the rotational constants accompanying the vibronic transitions corresponding to each band. The molecular rotational constants A, B, and C are revised for the upper state and for the two lower states, respectively.