• Title/Summary/Keyword: Emission Spectrum

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Characteristics of CaS:Eu,S electroluminescent devices (CaS:Eu,S 전계발광소자의 특성)

  • 조제철;유용택
    • Electrical & Electronic Materials
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    • v.8 no.6
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    • pp.752-758
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    • 1995
  • Red emitting CaS:Eu,S electroluminescent(EL) device prepared at 550.deg. C by an electron-beam evaporation technique, demonstrated luminance of 175cd/m$\^$2/ and efficiency of 0.311m/W with 3kHz drive. Luminance was increased with the increase of applied voltage and frequency. From the results of the PL spectrum and the EL spectrum, the CaS:Eu, S device showed emission peak near 640nm resulted from the transition of EU$\^$2+/ 4f$\^$6/5d.rarw.4f$\^$7/. The capacitance of the phosphor layer from the Sawyer-Tower circuit was 10.5nF/cm$\^$2/.

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Vibronic Assignments of the $S_1 \rightarrow S_0$ Emission Spectrum of the Jet Cooled p-Fluorotoluene

  • 하영미;최익순;이상국
    • Bulletin of the Korean Chemical Society
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    • v.19 no.2
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    • pp.202-206
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    • 1998
  • The p-fluorotoluene was vibronically excited in a jet with a buffer gas He in a corona excited supersonic expansion. The vibronic emission spectrum of the jet cooled p-fluorotoluene in the transition of S1 → S0 has been recorded with a Fourier transform spectrometer in the uv region. The spectrum observed was analyzed to obtain accurate vibrational frequencies in the ground electronic state by comparing with those reported previously. The origin of the low frequency sequence bands observed in this work was discussed. Also, the absence of significant intensity of hot band resulting from the excited vibrational states in the spectrum suggests extensive vibrational cooling in the source.

IMAGING NON-THERMAL X-RAY EMISSION FROM GALAXY CLUSTERS: RESULTS AND IMPLICATIONS

  • HENRIKSEN MARK;HUDSON DANNY
    • Journal of The Korean Astronomical Society
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    • v.37 no.5
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    • pp.299-305
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    • 2004
  • We find evidence of a hard X-ray excess above the thermal emission in two cool clusters (Abell 1750 and IC 1262) and a soft excess in two hot clusters (Abell 754 and Abell 2163). Our modeling shows that the excess components in Abell 1750, IC 1262, and Abell 2163 are best fit by a steep power law indicative of a significant non-thermal component. In the case of Abell 754, the excess emission is thermal, 1 ke V emission. We analyze the dynamical state of each cluster and find evidence of an ongoing or recent merger in all four clusters. In the case of Abell 2163, the detected, steep spectrum, non-thermal X-ray emission is shown to be associated with the weak merger shock seen in the temperature map. However, this shock is not able to produce the flatter spectrum radio halo which we attribute to post-shock turbulence. In Abell 1750 and IC 1262, the shocked gas appears to be spatially correlated with non-thermal emission suggesting cosmic-ray acceleration at the shock front.

Luminescent characteristics with coupling structure of Eu for ZnO:Eu Phosphor (Zno:Eu 형광체의 Eu 결합 구조에 따른 발광 특성)

  • 박용규;한정인;조황신;주성후
    • Electrical & Electronic Materials
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    • v.10 no.8
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    • pp.763-769
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    • 1997
  • In this study we have synthesized Zno:Eu phosphors under various sintering atmospheres and temperatures. The analysis of X-ray diffractometer measurement indicates that for Zno:EuCl$_3$ phosphors sintered in air and vacuum 뗘 exists in the host lattice as Eu$_2$O$_3$and EuOCl respectively. From the photoluminescence for the phosphors sintered in vacuum Eu removes the broad-band emission of the ZnO host consequently isolating the red emission due to Eu$^{3+}$ ion and improves the color purity of red emission. The photoluminescence excitation and time resolving spectrum measurements suggest that energy-transfer process occurres from the self-activated defect center in ZnO host the Eu$^{3+}$ ion which exist in the host lattice in the form of EuOCl.

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Study on Leak Detection of the Pipeline System by Acoustic Emission (음향방출(音響放出)에 의한 배관계(配管系)의 누출방지(漏出防止)에 관한 연구(硏究))

  • Yoon, D.J.;Kim, C.J.
    • Journal of the Korean Society for Nondestructive Testing
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    • v.7 no.1
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    • pp.7-17
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    • 1987
  • Leak detection testing for the pipeline system was performed by the acoustic emission method. It was found that the detected signal spectrum was influenced by the frequency response of sensors and pressure changes. AE parameters and frequency spectrum distributions were used to analyze the leak signals. The slope rise time of AE parameters were the important factors for distinguishing leak signals. The amplitude of leak signal was more affected by the changes of leak, rate and pressure than those of leak type.

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THE HIGH RESOLUTION SPECTRA OF PU VUL IN 2004 - I (2004년 PU VUL의 고분산 스펙트럼 - I)

  • Yoo, Kye-Hwa
    • Publications of The Korean Astronomical Society
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    • v.20 no.1 s.24
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    • pp.43-48
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    • 2005
  • We present a high resolution spectrum of PU Vul observed at Bohyunsan Optical Astronomy Observatory (BOAO) on April 9, 2004. Permitted emission and nebular lines of PU Vul had been significantly changed compared to all spectra observed since its eruption in 1979. Therefore all new lines should be re-identified and were done so. We do-convoluted a $H{\beta}$ line into several emission components with Gaussian functions. Then we carefully discussed the geometrical feature of PU Vul in April 2004.

The Acoustic Emission Energy Analysis of Subambient Pressure Tri-Pad Slider

  • Pan Galina;Hwang Pyung;Xuan Wu
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • 2004.11a
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    • pp.139-142
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    • 2004
  • The object of the present work is the acoustic emission energy analysis of subambient pressure tri-pad slider. Head/disk interaction during start/stop and constant speed were detected by using acoustic emission (AE) test system The frequency spectrum analysis is performed using the AE signal obtained during the head/disk interaction Natural frequency analysis was performed using Ansys program. Acoustic emission energy was calculated for the slider modes.

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Oil Fluorescence Spectrum Analysis for the Design of Fluorimeter (형광 광도계 설계인자 도출을 위한 기름의 형광 스펙트럼 분석)

  • Oh, Sangwoo;Seo, Dongmin;Ann, Kiyoung;Kim, Jaewoo;Lee, Moonjin;Chun, Taebyung;Seo, Sungkyu
    • Journal of the Korean Society for Marine Environment & Energy
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    • v.18 no.4
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    • pp.304-309
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    • 2015
  • To evaluate the degree of contamination caused by oil spill accident in the sea, the in-situ sensors which are based on the scientific method are needed in the real site. The sensors which are based on the fluorescence detection theory can provide the useful data, such as the concentration of oil. However these kinds of sensors commonly are composed of the ultraviolet (UV) light source such as UV mercury lamp, the multiple excitation/emission filters and the optical sensor which is mainly photomultiplier tube (PMT) type. Therefore, the size of the total sensing platform is large not suitable to be handled in the oil spill field and also the total price of it is extremely expensive. To overcome these drawbacks, we designed the fluorimeter for the oil spill detection which has compact size and cost effectiveness. Before the detail design process, we conducted the experiments to measure the excitation and emission spectrum of oils using five different kinds of crude oils and three different kinds of processed oils. And the fluorescence spectrometer were used to analyze the excitation and emission spectrum of oil samples. We have compared the spectrum results and drawn the each common spectrum regions of excitation and emission. In the experiments, we can see that the average gap between maximum excitation and emission peak wavelengths is near 50 nm for the every case. In the experiment which were fixed by the excitation wavelength of 365 nm and 405 nm, we can find out that the intensity of emission was weaker than that of 280 nm and 325 nm. So, if the light sources having the wavelength of 365 nm or 405 nm are used in the design process of fluorimeter, the optical sensor needs to have the sensitivity which can cover the weak light intensity. Through the results which were derived by the experiment, we can define the important factors which can be useful to select the effective wavelengths of light source, photo detector and filters.

Synthesis and optical properties of star-like ZnO nanostructures grown on with carbon catalyst (탄소 촉매에 의하여 성장된 별-모양 ZnO 나노 구조물의 합성과 광학적 특성)

  • Jung, Il-Hyun;Chae, Myung-Sic;Lee, Ui-Am
    • Journal of the Semiconductor & Display Technology
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    • v.9 no.2
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    • pp.1-6
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    • 2010
  • Star-like ZnO nanostructures were grown on SI(100) substrates with carbon(C) catalyst by employing vapor-solid(VS) mechanism. The morphologies and structure of ZnO nanostructures were investigated by Field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD) and Raman spectrum, Photoluminescence spectrum. The results demonstrated that the as-synthesized products consisted of star-like ZnO nanostructure with hexagonal wurtzite phase. Nanostructures grown at 1100 were mainly star-like in structure with diameters of 500 nm. The legs of the star-like nanostructures were preferentially grown up along the [0001] direction. A vapor.solid (VS) growth mechanism was proposed to explain the formation of the star-like structures. Photoluminescence spectrum exhibited a narrow emission band peak around 380 nm and a broad one around 491 nm. Raman spectrum of the ZnO nanostructures showed oxygen defects in ZnO nanostructures due to the existence of Ar gas during the growth process, leading to the dominant green band peak in the PL spectrum.

HIGH RESOLUTION SPECTRUM OF SYMBIOTIC STAR AG PEGASI (공생형 별 AG PEGASI의 고해상 스펙트럼)

  • Yoo, Kye-Hwa
    • Publications of The Korean Astronomical Society
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    • v.21 no.2
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    • pp.35-42
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    • 2006
  • We report a high resolution spectrum of AG Pegasi observed at Bohyunsan Optical Astronomy Observatory (BOAO) on October 2, 2004. Some of permitted emission lines, for example H I, He I, He II, Fe II and Ti II were observed in the spectrum of AG Pegasi in 2004. Lines presented in the longer wavelength region than $6500{\AA}$ are identified. And radial velocities for each element are measured. Then we carefully discuss the geometrical feature of AG Pegasi in October 2004.