• 제목/요약/키워드: exciplex

검색결과 65건 처리시간 0.028초

Photocycloaddition Reaction of 1,2-Bispyrazylethylene to Tetracyanoethylene

  • Shim, Sang-Chul;Shim, Hyun-Kwan
    • Bulletin of the Korean Chemical Society
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    • 제1권4호
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    • pp.123-126
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    • 1980
  • Benzene solution of trans-1,2-bispyrazylethylene and electron deficient olefin, tetracyanoethylene, as a ${\pi}$-acceptor gave 1,2-bispyrazyl-3,3,4,4-tetracyanocyclobutane, a 2${\pi}$ + 2${\pi}$ cycloaddition product, on irradiation with 350 nm UV light. Fluorescence studies revealed the reaction to proceed through a singlet exciplex. The fluorescence of trans-1,2-bispyrazylethylene was quenched very efficiently by tetracyanoethylene with the quenching constant of 1.6 ${\times}$ 10$^{10}$M$^{-1}$s$^{-1}$ while electron rich olefin, tetramethylethylene, did not quench the fluorescence of bispyrazylethylene.

3-유기층 구조를 갖는 고효율 청색 유기발광소자 (High Efficiency Blue Organic Light-Emitting Diode with Three Organic Layer Structure)

  • 장지근;지현진;김현;김재민
    • 반도체디스플레이기술학회지
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    • 제11권3호
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    • pp.33-37
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    • 2012
  • Simple and high efficiency blue organic light-emitting diodes with three organic layers of N, N'-diphenyl-N,N'-bis-[4-(phenyl-m-tolylamino)-phenyl]-biphenyl-4,4'-diamine[DNTPD]/1,1-bis-(di-4-polya-minophenyl)cyclohexane[TAPC]/electron transport material [ET-137] were fabricated and their electroluminescent characteristics were evaluated according to the TAPC thickness variation in a range of $50{\sim}300{\AA}$. Electroluminescence spectra of the devices with structure of DNTPD/TAPC/ET-137 showed all the same central emission wavelengths of 455 nm under an applied voltage of 7V, which were similar with that of the device with ET-137 only. On the other hand, the electroluminescence spectra of the device with structure of DNTPD/ET-137 without TAPC layer showed double emission peaks at the wavelengths of 455 nm and 561 nm under an applied voltage of 7V. In the devices with structure of DNTPD/TAPC/ET-137, single peak blue emission was not maintained in the device with $50{\AA}$-thick TAPC above 8V by the formation of exciplex. In the device with $300{\AA}$-thick TAPC, however, single peak blue emission was maintained until 10 V. According to the thickness increase of TAPC in the fabricated devices, the current density and luminance decreased, but the luminous efficiency and roll-off characteristics were improved.

벽면 형상에 따른 중공 원추형 분무의 벽 충돌 과정 모델링 (Modeling of Wall Impingement Process of Hollow-Cone Fuel Spray according to Wall Geometry)

  • 심영삼;최경민;김덕줄
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2007년도 춘계학술대회B
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    • pp.3467-3472
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    • 2007
  • The effects of the wall geometry on the spray-wall impingement process of a hollow-cone fuel spray emerging from a high-pressure swirl injector of the Gasoline Direct Injection (GDI) engine were investigated by means of a numerical method. The ized Instability Sheet Atomization (LISA) & Aerodynamically Progressed Taylor Analogy Breakup (APTAB) model for spray atomization process and the Gosman model were applied to model the atomization and wall impingement process of the spray. The calculation results of spray characteristics, such as a spray development process and a radial distance after wall impingement, compared with the experimental ones by the Laser Induced Exciplex Fluorescence (LIEF) technique. It was found that the radial distance of the cavity angle of 90$^{circ]$ after wall impingement was the shortest and the ring shaped vortex was generated near the wall after spray-wall impingement process.

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Solvatochromism, Aggregation and Photochemical Properties of Fullerenes, $C_{60} and C_{70}$, in Solution

  • Nath, Sukhendu;Pal, Haridas;Sapre, Avinash.V.;Mittal, Jai.P.
    • Journal of Photoscience
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    • 제10권1호
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    • pp.105-119
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    • 2003
  • Fullerenes, $C_{60}$ and $C_{70}$, display interesting physicochemical properties in solutions, especially due to their unique chemical structures and their good electron accepting abilities. Solubility of fullerenes in different organic solvents and their unusual solvatochromic behavior, the ability of the fullerenes to form aggregates in solutions, and their electron transfer and charge transfer interactions with variety of electron donors, are the subjects of extensive research activities for more than one decade. Many research groups including ours have contributed substantially in the understanding of the solvatochromism, aggregation behavior, and the photoinduced electron transfer and charge transfer chemistry of fullerenes, in condensed phase. Present article is aimed to summarize the important results reported on the above aspects of fullerenes, subsequent to the earlier report from our group (D.K. Palit and J.P. Mittal, Full. Sci. & Tech. 3, 1995, 643-659).)., 643-659)..

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고온.고압의 분위기 조건에서 GDI 분무의 분열 및 증발과정에 대한 수치적 연구 (The Numerical Study on Breakup and Vaporization Process of GDI Spray under High-Temperature and High-Pressure Conditions)

  • 심영삼;황순철;김덕줄
    • 한국자동차공학회논문집
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    • 제12권3호
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    • pp.44-50
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    • 2004
  • The purpose of this study is to improve the prediction ability of the atomization and vaporization processes of GDI spray under high-pressure and high-temperature conditions. Several models have been introduced and compared. The atomization process was modeled using hybrid breakup model that is composed of Conical Sheet Disintegration (CSD) model and Aerodynamically Progressed TAB(APTAB) model. The vaporization process was modeled using Spalding model, modified Spalding model and Abramzon & Sirignano model. Exciplex fluorescence method was used for comparing the calculated with the experimental results. The experiment and calculation were performed at the ambient pressure of 0.5 MPa and 1.0 MPa and the ambient temperature of 473k. Comparison of caldulated and experimental spray characteristics was carried out and Abramzon & Sirignano model and modified Spalding model had the better prediction ability for vaporization process than Spalding model.

증발디젤분무의 혼합기 형성과정에 대한 열역학적 접근 (Thermodynamic Approach to the Mixture Formation Process of Evaporative Diesel Spray)

  • 염정국
    • 대한기계학회논문집B
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    • 제33권3호
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    • pp.201-206
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    • 2009
  • The focus of this work is placed on the analysis of the mixture formation process under the evaporative diesel-free spray conditions. In order to examine homogeneity of mixture within the vapor phase region of the injected spray, image analysis was carried out based on the entropy of statistical thermodynamics. As an experimental parameter, the injection pressure and ambient gas density were selected, and effects of the injection pressure and density variation of ambient gas on the mixture formation process in the evaporative diesel spray were investigated. In the case of application of the thermodynamic entropy analysis to evaporative diesel spray, the value of the dimensionless entropy always increases with increase in time from injection start. Consequently, the dimensionless entropy in the case of the higher injection pressure is higher than that of lower injection pressure during initial injection period.

INVESTIGATION OF TRIPLET STATE AND SINGLET OXYGEN DYNAMICS OF BENZOPHENONE IN POLAR AND NONPOLAR SOLUTIONS WITH TIME-RESOLVED TWO-COLOR THERMAL LENSING METHOD

  • Ha, Jeong-Hyon
    • Journal of Photoscience
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    • 제3권3호
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    • pp.141-145
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    • 1996
  • The heat generated by nonradiative decay dynamics induces thermal lens effect. From such an effect, photodynamic properties of solutions can be investigated with two-color pulsed thermal lens experiments which have the time resolution of down to nanoseconds. In this study, using nanosecond two-color thermal lens method, we investigated the triplet state of benzophenone and the singlet oxygen state dynamics in various oxygen concentration solvents. The measured triplet state lifetimes, singlet oxygen relaxation times and singlet oxygen formation quantum yields are in good agreement with the reference values. From these parameters the existence of the triplet exciplex formation between benzophenone and benzene is proved, and it is also suggested that the relaxations of triplet states of benzophenone undergo coupled dynamics with some of singlet oxygens in oxygen-rich conditions.

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증발 충돌분무의 거동특성에 관한 실험연구 (An Experimental Analysis on the Behavior Characteristics of Evaporative Impinging Spray)

  • 염정국
    • 동력기계공학회지
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    • 제14권2호
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    • pp.16-21
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    • 2010
  • 분사된 연료의 미립화(atomization), 증발(evaporation), 그리고 혼합기형성과정(mixture formation process)이 디젤엔진의 착화 및 연소특성에 영향을 미치기 때문에, 디젤엔진 내에 분사된 연료의 구조해석으로부터 일련의 과정, 즉 고압분사, 분열(breakup), 미립화, 그리고 주위기체의 난류 도입(entrainment)에 관한 연구$^{1-3)}$는 꾸준히 행해져왔다. 본 연구는 증발디젤분무의 구조해석으로부터 디젤충돌분무의 혼합기형성과정을 조사한다. 주위기체의 밀도는 실험변수로서 선택하였고, $5.0kg/m^3$에서 $12.3kg/m^3$까지 변화시켰다. 그리고 소형고속디젤엔진에 있어서 연료분사초기의 상태의 고온 고압 설정이 가능한 정적용기를 사용했다. 주위 온도와 연료분사압력은 각각 700K 및 72MPa로 일정하게 유지했다. 충동증발분무의 액상과 기상의 이미지는 엑시플렉스형광법으로 동시 계측하였다. 실험결과로서 주위기체의 밀도가 높을수록 충돌분무의 선단도 달거리가 주위기체의 항력으로 인하여 감소하였다.

분위기 조건에 따른 GDI 엔진용 인젝터의 분무거동 및 증발특성에 대한 수치적 해석 (Numerical Analysis of Spray Behavior and Vaporization Characteristic of GDI Engine Injector Under Ambient Conditions)

  • 심영삼;황순철;김덕줄
    • 대한기계학회논문집B
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    • 제28권5호
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    • pp.545-552
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    • 2004
  • The purpose of this study is to improve the prediction ability of the atomization and vaporization processes of GDI spray. Several models have been introduced and compared. The atomization process was modeled using hybrid breakup model that is composed of Linearized Instability Sheet Atomization (LISA) model and Aerodynamically Progressed TAB (APTAB) model. The vaporization process was modeled using Spalding model and Abramzon & Sirignano model. Exciplex fluorescence method was used for comparing calculated with experimental results. The experiment and computation were performed at the ambient pressure of 0.1 MPa, 0.5 MPa and 1.0 MPa and the ambient temperature of 293k and 473k. Comparison of calculated and experimental spray characteristics was carried out and the calculated results of GDI spray showed good agreement with experimental results.

분위기 조건에 따른 GDI 분무거동의 수치적 연구 (The Numerical Study of GDI Spray Behavior on Various Ambient Conditions)

  • 심영삼;황순철;김덕줄
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2003년도 추계학술대회
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    • pp.466-471
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    • 2003
  • The purpose of this study is to obtain the accurate prediction for the atomization and vaporization processes of GDI spray. Atomization process is modeled using hybrid model that is composed of Linearized Instability Sheet Atomization (LISA) model and Aerodynamically Progressed TAB (APTAB) model. Vaporization process is modeled using Spalding model and Abramzon & Sirignano model. To obtain the experimental results for comparing with calculated results, the cross-sectional images of liquid and vapor phases and SMD distribution were acquired by exciplex fluorescence method and Phase Doppler Analyzer respectively. The experiment and computation was performed at the ambient pressure of 0.1 MPa, 0.5 MPa, 1.0 MPa and the ambient temperature of 293K, 473K. The calculated results by modified KIVA-II code show good agreement with experimental results.

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