• Bulletin of the Korean Chemical Society
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• 제23권10호
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• pp.1404-1408
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• 2002

The resonance Raman spectra of trans-polyacetylene films doped heavily with electron donor (Na) and acceptor (HClO4) have been measured with excitation wavelengths between 488- and 1320-nm, and the relationships between the Raman excitation photon energies (2.54-0.94 eV) and its wavenumbers were discussed. We found the linear dependence of the Raman shifts with the exchanges of excitation photon energies. In particular, the Raman wavenumbers in the C=C stretching $(V_1$ band) showed a dramatic decrease with the increase in Raman excitation photon energies. In the case of acceptor doping, its change is larger than that of donor doping. The observed wavenumber (1255-1267 $cm^{-1}$) of the $V_2$ band (CC stretch) of Na-doped form is lower than that of the corresponding band (1290-1292 $cm^{-1}$) of its pristine trans-polyacetylene, whereas the contrary is the case for the HClO4 doped form (1295-1300 $cm^{-1}$). The origin of doping-induced Raman bands is discussed in terms of negative and positive polarons.

• Bulletin of the Korean Chemical Society
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• 제34권8호
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• pp.2276-2280
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• 2013

The accurate prediction of vertical excitation energies is very important for the development of new materials in the dye and pigment industry. A time-dependent density functional theory (TD-DFT) approach coupled with 22 different exchange-correlation functionals was used for the prediction of vertical excitation energies in the halogenated copper phthalocyanine molecules in order to find the most appropriate functional and to determine the accuracy of the prediction of the absorption wavelength and observed spectral shifts. Among the tested functional, B3LYP functional provides much more accurate vertical excitation energies and UV-vis spectra. Our results clearly provide a benchmark calibration of the TD-DFT method for phthalocyanine based dyes and pigments used in industry.

• International Journal of Naval Architecture and Ocean Engineering
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• 제8권2호
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• pp.117-126
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• 2016

In this paper, a numerical procedure for the natural vibration analysis of plates with openings and carlings based on the assumed mode method is extended to assess their forced response. Firstly, natural response of plates with openings and carlings is calculated from the eigenvalue equation derived by using Lagrange's equation of motion. Secondly, the mode superposition method is applied to determine frequency response. Mindlin theory is adopted for plate modelling and the effect of openings is taken into account by subtracting their potential and kinetic energies from the corresponding plate energies. Natural and frequency response of plates with openings and carlings subjected to point excitation force and enforced acceleration at boundaries, respectively, is analysed by using developed in-house code. For the validation of the developed method and the code, extensive numerical results, related to plates with different opening shape, carlings and boundary conditions, are compared with numerical data from the relevant literature and with finite element solutions obtained by general finite element tool.

• Bulletin of the Korean Chemical Society
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• 제16권7호
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• pp.574-577
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• 1995

Solvatochromic effect and hydrogen bonding interaction of NPNOH, NPNO- and NPNOR were investigated. Electronic transition energies of the dyes were plotted against empirical solvent polarity parameters, Taft's π* and Reichardt's ET(30). Good correlations were observed when the excitation energies were plotted against the energy calculated by multiple linear regression method which was developed by Taft. There is an intrinsic difference between betaine for ET(30) polarity scale and the azoderivative, which is derived from the specific hydrogen bond incurred with probe molecules and solvents. The hydrogen bonding plays a very important role for stabilization of an excited state molecule by solvents especially when a solute possesses a negative charge as with NPNO-.

• Bulletin of the Korean Chemical Society
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• 제11권3호
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• pp.224-227
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• 1990

The excitation mechanism of polycyclic aromatic amines (amino-PAHs) and polycyclic aromatic hydrocarbons(PAHs) for the chemiluminescence arising from the reaction between oxalate ester, bis(2,4,6-trichlorophenyl)oxalate (TCPO) or bis(2,4-dinitrophenyl)oxalate (DNPO) and hydrogen peroxide has been studied in terms of the excitation efficiencies to singlet excitation energies and the oxidative half-wave potentials. As a results of the study, the excitations of both amino-PAHs and PAHs appear to involve the charge transfer type of energy transfer. However the chemiluminescence efficiency corrected for fluorescence quantum yield of the amino-PAHs are varied more sensitively to the oxidative half-wave potential than that of PAHs possibly due to the large difference in solvation energy between the compounds and their ions.

• 대한화학회지
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• 제45권5호
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• pp.401-412
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• 2001

$H_{2n+1}^+$ (n=1~6) cluster들에 대하여 높은 수준의 순 이론적(ab initio) 양자역학적 방법을 사용하여 분자 구조, 진동 주파수(vibrational frequency), 그리고 해리 에너지 등을 계산하였다. 분자구조는 $H^+_g$까지는 TZ2P+ d CCSD(T) 수준에서 그리고 $H_{11}^+$과 $H_{13}^+$에 대해서는 TZ2P CCSD(T) 수준까지 최적화하였다. 진동 주파수는 여러 basis set에서 SCF 방법으로 계산하였으며, 본 연구에서 최적화된 모든 분자구조들이 local minimum 구조임을 확인하였다. $H_{2n+1}^+$로부터 $H_2$ 의 해리 에너지($D_e$)는 각각의 최적화된 분자구조에서의 에너지 차로부터 계산하였으며, 영점 진동에너지(ZPVE)를 고려하여, 지금까지의 이론 및 실험결과($D_0$)와 비교하였다.

• Bulletin of the Korean Chemical Society
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• 제16권6호
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• pp.547-552
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• 1995

As an extension to the Kramers' restricted Hartree-Fock (KRHF) method [J. Comp. Chem., 13, 595 (1992)], we have implemented the Kramers' restricted configuration interaction (KRCI) program in order to calculate excited states as well as the ground state of polyatomic molecules containing heavy atoms. This KRCI is based on determinants composed of the two-component molecular spinors which are generated from KRHF calculations. The Hamiltonian employed in the KRHF and KRCI methods contains most of all the important relativistic effects including spin-orbit terms through the use of relativistic effective core potentials (REP). The present program which is limited to a small configuration space has been tested for a few atoms and molecules. Excitation energies of the group 14 and 16 elements calculated using the present KRCI program are in good accordance with the spectroscopic data. Calculated excitation energies for many Rydberg states of K and Cs indicate that spin-orbit terms in the REP, which are derived for the ground state, are also reliable for the description of highly excited states. The electronic states of the polyatomic molecule CH3I are probed from the molecular region to the dissociation limit. Test calculations demonstrate that the present KRCI is a useful method for the description of potential energy surface of polyatomic molecules containing heavy atoms.

• Nuclear Engineering and Technology
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• 제49권5호
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• pp.996-1005
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• 2017

In this paper, nuclear data for cross sections of the $^{64}Zn(n,2n)^{63}Zn$, $^{64}Zn(n,3n)^{62}Zn$, $^{64}Zn(n,p)^{64}Cu$, $^{66}Zn(n,2n)^{65}Zn$, $^{66}Zn(n,p)^{66}Cu$, $^{67}Zn(n,p)^{67}Cu$, $^{68}Zn(n,p)^{68}Cu$, and $^{68}Zn(n,{\alpha})^{65}Ni$ reactions were studied for neutron energies up to 40 MeV. In the nuclear model calculations, TALYS 1.6, ALICE/ASH, and EMPIRE 3.2 codes were used. Furthermore, the nuclear data for the (n,2n) and (n,p) reaction channels were also calculated using various cross-section systematics at energies around 14-15 MeV. The code calculations were analyzed and obtained using the different level densities in the exciton model and the geometry-dependent hybrid model. The results obtained from the excitation function calculations are discussed and compared with literature experimental data, ENDF/B-VII.1, and the TENDL-2015 evaluated data.

• 대한화학회지
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• 제47권4호
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• pp.325-333
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• 2003

1,2-와 1,3-dioxetane$(C_2O_2H_4)$, 그리고 1,3-cyclodisiloxane$(Si_2O_2H_4)$에 대하여 높은 이론 수준에서 분자구조, 진동주파수, 그리고 에너지 등을 계산하였다. 위의 모든 분자들에 대하여 TZ2P CCSD(T)의 이론 수준까지 분자구조를 최적화 하였으며. 진동주파수는 여러 basis set에서 SCF 방법으로 계산하였다. 본 연구에서 최적화된 분자구조들에 대한 진동주파수가 모두 실수(real number)로 예측됨으로서, 제안된 모든 분자구조가 local minimum 구조임을 확인하였다. 1,2- 및 1,3-dioxetane들과 cyclodisiloxane이 두 분자의 aldehyde와 silanone으로 해리 될 때의 중합에너지를 zero-point vibrational energy(ZPVE)를 고려하여 계산하고, 안정성을 비교하였다.

• 한국세라믹학회지
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• 제37권2호
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• pp.111-116
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• 2000

700nm red emission(3F3longrightarrow3H6) in Tm3+ ion with 800 nm(3H6longrightarrow3H4) excitation via upconversion process has been reported only in host materials which have low phonon energies such as halide crystals. However, we observed 700nm and 480nm(1G4longrightarrow3H6) upconverted emission with 800nm excitation in several oxide glasses which has never reported. With spectroscopic analyses and lifetime measurements of each nergy level of Tm3+ ion doped in various oxide glasses, following mechanisms are suggested. For red upconversion, upconversion mechanism changed with Tm3+ concentration. While direct excitation up to 3F3 level via anti-Stokes excitation was dominated at low concentration, two-step excitation via 3H6longrightarrow3H4 and 3F4longrightarrow3F3 transitions was dominated at high concentration. For blue upconversion, two step excitation mechanism up to 1G4 level was suggested as follows : electrons are exciated up to 3H5 with direct excitation with pumping light up to 3H4 followed by multiphonon relaxation, and then additional reabsorption of pumping light excites electrons up to 1G4.