• Journal of the Korean Ceramic Society
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• v.34 no.4
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• pp.429-435
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• 1997

The third order nonlinear optical susceptibilities, {{{{ chi }}(3), of the CuCl doped alumino-borosilicate glasses were measured by the two beam configuration DFWM method and the absorption saturation method, and the measured {{{{ chi }}(3) values were about 10-8 esu in both methods. The response time was estimated to be about 105ps from the time decay curve of the luminescence spectra obtained by time-correlated single-photon counting (TCSPC) method.

• Transactions on Electrical and Electronic Materials
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• v.6 no.4
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• pp.169-172
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• 2005

[ $Y_2O_3:Eu$ ] powder was synthesized using a solution-combustion method by dissolving $(CH_3CO_2)_3Y$ and $(CH_3CO_2)_3$ Eu in methyl-alcohol solution. Results from X-ray diffractometery (XRD), thermogravimetry (TG)-differential thermal analysis (DTA) show that $Y_2O_3:Eu$ crystallizes completely when the dry powder is sintered at $500^{\circ}C$. The investigated optical properties were the photoluminescence emission spectra, the excitation spectra and luminescence decay curve. Europium (Eu) concentration had no observable effect on the optical spectrum which depended on the emission intensity. The mean lifetime of synthesized phosphors was $2.3\~2.6 ms$.

• Rapid Communication in Photoscience
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• v.4 no.4
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• pp.76-78
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• 2015

We report on the photoluminescence (PL) properties of poly[2,7-(9-9-dioctylfluorene)] (PF) thin film under strong optical pumping using a streak camera system. When the excitation energy density increases above $72{\mu}J{\cdot}cm^{-2}$, the emission spectrum becomes narrower and PL decay curve comes to be faster simultaneously. These behaviors are clear evidence of Amplified Spontaneous Emission (ASE) due to a waveguided Stimulated Emission in slab structure of thin film. ASE threshold of $72{\mu}J{\cdot}cm^{-2}$ is comparable with previous reports and PF is attractive as a gain medium for plastic lasers.

• Journal of the Korean Chemical Society
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• v.45 no.6
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• pp.570-576
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• 2001

The europium doped yttrium oxybromide phosphors were synthesized by solid-state reaction method. The YOBr: $Eu^{3+}$ phosphor showed a strong and narrow red emission band at 621 nm and maximum emission intensity obtained when 0.05 mol Eu ions were doped. The red emission of $Eu^{3+}$ originated from $^5D_0$ ${\rightarrow}$ $^7F_2$electric dipole transition. In order to investigate on photoluminescence behavior, several experimental skills and numerical fittings are conducted to the YOBr: $Eu^{3+}$ phosphor. The emission spectrum was measured in the UV range and then decay curve of $^5D_0$ ${\rightarrow}$ $^7F_j$transitions was examined. The energy interaction type of YOBr: $Eu^{3+}$ phosphor was dipole-dipole interaction. In addition to the calculating by critical concentration, the critical distance ($R_0$) was calculated by decay curve fitting parameter from Inokuti-Hirayamas equation, and spectral overlap method. The critical distance was 17.03, 10.51 and 7.18$\AA$ for those methods, respectively. As considering systematic error of measurements, these values are within the same order, so that the above fitting methods are plausible and recommendable.

• Korean Journal of Materials Research
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• v.26 no.9
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• pp.504-511
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• 2016

To prepare $Mn^{4+}$-activated $K_2TiF_6$ phosphor, a precipitation method without using hydrofluoric acid (HF) was designed. In the synthetic reaction, to prevent the decomposition of $K_2MnF_6$, which is used as a source of $Mn^{4+}$ activator, $NH_5F_2$ solution was adopted in place of the HF solution. Single phase $K_2TiF_6$:$Mn^{4+}$ phosphors were successfully synthesized through the designed reaction at room temperature. To acquire high luminance of the phosphor, the reaction conditions such as the type and concentration of the reactants were optimized. Also, the optimum content of $Mn^{4+}$ activator was evaluator based on the emission intensity. Photoluminescence properties such as excitation and emission spectrum, decay curve, and temperature dependence of PL intensity were investigated. In order to examine the applicability of this material to a white LED, the electroluminescence property of a pc-WLED fabricated by combining the $K_2TiF_6$:$Mn^{4+}$ phosphor with a 450 nm blue-LED chip was measured.

• Journal of the Korean Vacuum Society
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• v.1 no.3
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• pp.360-370
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• 1992

HWE(Hot-Wall Epitaxy) 방법에 의하여 pyrex 유리기판 위에 CdS 다결정 박막을 성장하였다. X-선 회절실험 결과 CdS 박막은 육방정이었는데 (0002)면보다 91013)면이 강 하게 성장됨을 알 수 있었다. 전자현미경으로 표면을 분석한 결과 입자의 크기는 기판의 온 도가 48$0^{\circ}C$, 증발원의 온도가 $610^{\circ}C$일 때 1~1.5$mu extrm{m}$로서 가장 컸다. 박막의 표면저항은 4-point probe로서 측정한 결과 10-8$\Omega$/\ulcorner이상이었다. 성장된 CdS 다결정 박막의 photoluminesence을 20K에서 측정하였는데 bound exciton, donor acceptor pair에 의한 발광이 관측되었다. Spectral response의 peak는 505nm이었다. CdS 다결정 박막의 표면 저항을 줄이기 위하여 여러 가지 온도에서 Indium을 확산시켰다. 그 결과 표면저항은 ~ $\times$ 101에서 ~ $\times$ 103$\Omega$/\ulcorner 정도 감소되었다. 50$0^{\circ}C$에 In을 1시간 확산시켰을 때 표면저항은 1300$\Omega$/\ulcorner이었다. 이 때 CdS : In의 운반자 농도는 1.2 $\times$ 1018cm-3, 이동도는 1.8cm-2/V-sec, 비저항은 1.3 $\times$ 10-2$\Omega$-cm이었다. CdS : In의 photoluminescence는 20K 에서 Gaussian curve를 보여 주었으며 peak의 위치는 510nm이었다. CdS : In 박막의 spectral response의 peak는 상온에서 500nm이다. CdS : In 광전도 cell의 sensitivity ${\gamma}$ =0.77이고, 최대 허용소비전력은 p=120mW, 100lux에서 rise time은 8 msec, decay time 은 6 msec이다.

• Journal of the Korean Chemical Society
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• v.44 no.5
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• pp.453-459
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• 2000

FED has deserved an intensive attentioD as a new flat panel display. The present investigationaims at undemtanding the photoluminescence and cathodoluminescent properties of hGaO$_3$: $Eu^{3+}$ phosphor bytaking into account the possibility that this phosphor could be applied for FED. In onler to investigate on.sucha detailed behavior; 8everM experimental skil18 Je conducted to the LaGaO$_3$:$Eu^{3+}$ phosphoL The excimtion srectrum artd emission spectmn were rnezsured in the UV range and then decay curve of $^5D_0$+$^7F_j$transitions\vas examined. The decay behavior of $^5D_0$ emission was anMyzed by a newly Iuoposed cross-relaxation mech-ani8In in asswiation with inteFwnter di1ffision (or migration). The cross-mlaxation from $^5D_0$ to CTB (Cha'geTransfer Band) wuld be a quite retsonable by considering the excitation spectrum. It could be also found thatthe quenching type was changed from ditfrsion controlled process to the direct quenching process -s inJeasing $Eu^{3+}$ oncntration.