• Bulletin of the Korean Chemical Society
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• v.26 no.10
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• pp.1575-1578
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• 2005

• Journal of Electrical Engineering and Technology
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• v.11 no.5
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• pp.1362-1366
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• 2016

• Korean Journal of Optics and Photonics
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• v.17 no.1
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• pp.81-88
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• 2006

Delayed luminescence from human hands after illumination by light at different wavelength bands was studied. A delayed luminescence measurement system equipped with photomultiplier tube (PMT), fiber optics and automatic mechanical shutter system was developed. Three spectrum band-pass filters, fer which transmissions are on 350${\~}$450 nm, 450${\~}$550 nm and 550${\~}$650 nm, were used to select irradiation wavelength, and 150W metal-halide lamp was used as an illumination source. Six volunteers put their palms (dorsa) onto the measurement system, and after light illumination, delayed luminescence were measured for 10 minutes. The results show that delayed luminescence after shorter wavelength illumination was higher than that a(ter longer wavelength one. These results indicate the existence of accepters in human skin which can be excited at short wavelengths. Furthermore, each subjects showed different delayed luminescence curve patterns. Reactive oxygen species (ROS) are known to have important roles on delayed luminescence, and this research suggests that ROS concentration can be measured noninvasively with optical methods.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.8
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• pp.900-906
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• 2005

The responses of two luminescence-based biosensors were studied on various heavy metals in aqueous solutions. One was recombinant E. coli ($DH5{\alpha}$/pSB311), genetically modified luminescence-based bacteria, and the other was Vibrio fisheri used for the LumisTox system. The recombinant E. coli was marked with the lux CDABE gene from multicopy plasmid, pACYC184, originally isolated from Photorhabdus luminescens. The $DH5{\alpha}$/pSB311 had a characteristic of no organic substrate for its luminescence reaction. Among the tested heavy metals Zinc and cadmium were less toxic than copper and mercury. The recombinant E. coli was more sensitive to toxicity of heavy metals than the LumisTox. The order of toxicity of the heavy metals to the recombinant E. coli was $Hg^{2+}>Cu^{2+}>Zn^{2+}>Cd^{2+}$. In case of the LumisTox, the order of the toxicity of heavy metals was $Hg^{2+}>Cu^{2+}>Cd^{2+}>Zn^{2+}$. The genetically modified luminescence-based biosensor offers a range of sensitive, rapid, and easy to use methods for assessing the potential toxicity of heavy metals in aqueous samples.

• The Korean Journal of Ceramics
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• v.2 no.3
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• pp.137-141
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• 1996

Ambient air aged anodically etched porous silicon (PS) and spark-processed silicon (sp-Si) show interesting similarities and dissimilarities in some of their luminescence-related properties. Among these similarties are: (1) the photoluminescence (PL) peak maximum in the blue/violet (410 nm);(2) the blue/violet PL peak positions are essentially unchanged with temperature ; (3) PL decay times in the nanosecond region which are independent of the detection wavelength, which is much faster in decay times compared to that of observed decay time in $SiO_2$.Among the dissimilarities are: (1) the PL intensity of blue/violet luminescence, namely, the PL intensity of sp-Si is at least 2 orders of magnitude larger than that of an ambient air aged PS; (2) the blue/violet PL intensity of sp-Si is more stable than that of ambient air aged PS under UV illuminations; (3) FTIR spectra of sp-Si favor those modes, which involve silicon -oxygen bonds in $SiO_2$ stoichiometry, whereas ambient air aged PS can be considered as a nonstoichiometric oxide judging from the observed vibrational spectra.

• Bulletin of the Korean Chemical Society
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• v.34 no.9
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• pp.2774-2780
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• 2013

Two new isostructural dinuclear complexes, $Ln_2(4-cpa)_6(bpy)_2$ (Ln = Eu (1); Tb (2), 4-cpa = 4-chlorophenylacetate, bpy = 2,2'-bipyridine), have been hydrothermally synthesized and characterized by IR spectroscopy, elemental analysis, thermogravimetric analysis (TGA), powder X-ray diffraction and single-crystal X-ray diffraction. The lanthanide ions are bridged by two bidentate and two terdentate carboxylate groups to give centrosymmetric dimers with $Ln{\cdots}Ln$ separations of 3.967(2) and 3.956(3) ${\AA}$, respectively. Each metal atom is nine-coordinate and exhibits a distorted tricapped trigonal prismatic geometry. Three-dimensional fluorescence spectra show that both 1 and 2 emit bright red and green luminescence at room temperature, with long lifetimes of up to 0.369 ms (at 614 nm) and 0.432 ms (at 543 nm), respectively. Moreover, poor luminescence efficiency has been noted for complex 2. The 4-Hcpa ligand and complexes 1-2 have been screened for their phytogrowth-inhibitory activities against Brassica napus L. and Echinochloa crusgalli L., and the results are compared with the activity of quizalofop-P-ethyl.

• The Korea Journal of Herbology
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• v.21 no.2
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• pp.175-180
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• 2006

Objectives : The difference of delayed luminescence-biophoton emission was investigated in Cervi Pantotrichum Cornu selected randomly. Cervi Pantotrichum Cornu was used as a tonic in Korean medicine. Methods : Randomly selected samples of Cervi Pantotrichum Cornu were radiated with 150 W metal halide lamp for 1 minute. After radiation, biophoton emissions of each sample were detected by electron multiplication(EM)-charge coupled device camera. The detected biophoton image was calculated with unit of counts per pixel. Results : The average biophoton emissions of delayed luminescence with EM ratio of ${\times}l50\;and\;{\times}250$ were distinguished significantly. The maximum biophoton emissions of delayed luminescence with EM ratio of ${\times}250$ were distinguished significantly. Conclusion : These results suggest that biophoton imaging of Cervi Pantotrichum Cornu could become the meaningful method for the study of differentiation and classification of Cervi Pantotrichum Cornu.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.23 no.3
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• pp.142-145
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• 2013

The upconversion (UC) luminescence of $Li^+/Er^{3+}/Yb^{3+}$ co-doped $CaWO_4$ phosphors and effects of $Yb^{3+}$ concentration are investigated in detail. Single crystallized $CaWO_4$ : $Li^+/Er^{3+}/Yb^{3+}$ phosphor can be obtained, co-doped up to 35.0/5.0/30.0 mol% ($Li^+/Er^{3+}/Yb^{3+}$) by solid-state reaction. Under 980 nm excitation, $CaWO_4$ : $Li^+/Er^{3+}/Yb^{3+}$ phosphor exhibited strong green UC emissions visible to the naked eye at 530 and 550 nm induced by the intra 4f transitions of $Er^{3+}$ ($^4H_{11/2}$, $^4S_{3/2}{\rightarrow}^4I_{15/2}$). The optimum doping concentrations of $Yb^{3+}$ that would result in the highest UC luminescence were determined, and a possible UC mechanism that depends on the pumping power is discussed in detail.

• Bulletin of the Korean Chemical Society
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• v.31 no.8
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• pp.2151-2157
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• 2010

Spectroscopic and quantum mechanical studies of the Et3PAuCl complex were performed to characterize the effect of aurophilicity on the optical properties. When excited with UV light at low temperature, the crystalline complex produced a deep luminescence in both the blue (high-energy) and red (low-energy) regions of the spectrum. The intensity of the low-energy luminescence was markedly reduced in the powdered state and quenched in the solution state. Time-dependent density functional theory (TD-DFT) calculations on electronic structures of both the ground and excited states of aggregates $[Et_3PAuCl]_n$ (n = 1 - 3) indicated that the low-energy luminescence was attributable to Au-centered transitions, which are significantly affected by aurophilic interactions. By contrast, the high-energy luminescence appeared to be independent of the state of the complex and was strongly associated with the charge transfer from Cl to Au.

• Journal of the Korean Ceramic Society
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• v.41 no.5
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• pp.359-363
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• 2004

Photoluminescence excitation (PLE) spectroscopy studies were performed for anodically etched porous Zn, which exhibited a PL in the blue/violet spectral range peaking at 420 nm (2.95 eV), and oxidzed porous Zn at 380$^{\circ}C$ for 10 min and 12 h. A broad absorption band was observed at 4.07 eV (305 nm), 3.49 (355 nm) for anodically etched porous Zn. In contrast, both the oxidized porous Zn and sintered ZnO exhibited an almost identical one broad absorption band at 3.85 eV (322 nm), when PLE spectra were measured at 378 nm (3.28 eV). The oxidized porous Zn and sintered ZnO, which displayed both UV and green luminescence band, showed an additional absorption band at 389 nm (3.19 eV) and 467 nm (2.66 eV). In contrast, no significant absorption band was detected for a 10-min oxidized porous Zn, which only displayed one UV luminescence void of deep-level luminescence. These absorption bands determined by PLE studies enabled a clear understanding of an emission mechanism for the UV and green luminescence from ZnO.