• Title/Summary/Keyword: Phosphorescence

Search Result 110, Processing Time 0.033 seconds

Triplet Excitation Energy Transfer in Choleic Acid Crystals

  • Kook, Seong-Keun
    • Bulletin of the Korean Chemical Society
    • /
    • v.28 no.12
    • /
    • pp.2409-2413
    • /
    • 2007

  • Time resolved phosphorescence of Dibromobenzophenone (DBBP) choleic acid crystal was observed at 4.2 K as functions of excitation energy and delay time. The experimental results reveal that the energy transfer efficiency is dependent on the excitation energy, i.e. the density of acceptors sites. As the excitation energy or delay time increases, the resonance phosphorescence does not broaden and shift gradually, rather a broad luminescence band develops about 290 cm?1 to lower energy of the resonance phosphorescence. The observation implies that energy transfer from high to low energy sites in this system is controlled by emission of phonons or vibrons. The data of time resolved experiments were analyzed in terms of a mechanism involving direct donor-acceptor excitation transport by exchange coupling. It was concluded that an isotropic twodimensional exchange interaction topology is consistent with energy transfer in this system.

  • https://doi.org/10.5012/bkcs.2007.28.12.2409 인용 PDF KSCI

The Effect of Vibrationally Excited Levels on the Pressure Saturation of the Collisional Quenching of the $^3B_1\;State\;of\;SO_2

  • Bae, S. C.
    • Bulletin of the Korean Chemical Society
    • /
    • v.17 no.1
    • /
    • pp.56-60
    • /
    • 1996

  • The pressure saturation effect on the phosphorescence decay rates of the $^3B_1$ State of $SO_2$ has been reinvestigated by the laser induced phosphorescence method in pure $SO_2$. We have attempted to fit the pressure dependence of the phosphorescence decay rates using the radiationless transition model by introducing different coupling constants for each vibrational level ofthe 3B1 state. The experimental decay rates can be fitted well, when the coupling constants for the (0,0,0), (0,1,0) and (0,2,0) levels of the $^3B_1$ state are $7.2\;{\times}\;10^{-4}$, $2.2\;{\times}\;10^{-3}$ and $5.9\;{\times}\;10^{-3}\;cm^{-1}$, respectively.

  • https://doi.org/10.5012/bkcs.1996.17.1.56 인용 PDF

Study on the Safe Evacuation Management in a Power Supply Disturbed Emergency

  • Suzuki, Nobuyuki;OHASHI, Tsubasa;WHORLOW, James R
    • International conference on construction engineering and project management
    • /
    • 2015.10a
    • /
    • pp.87-91
    • /
    • 2015

  • For construction projects it is imperative that site management gives the highest priority to planning safe site evacuation for all foreseeable emergencies, including earthquakes and typhoons which are often experienced in Japan. This is especially important and even more critical for high risk projects involving underground works, such as Tunneling & Pneumatic Caissons. Based on the safety regulation of underground works, a back-up power supply system must be provided during the construction period at all times. Often, fluorescent lamps with re-chargeable batteries are provided for infrequent emergency cases, however these have a questionable useable life span and thus need careful maintenance and periodical replacement. In this paper we focused on using the phosphorescence materials to indicate the evacuation direction. As a result, it was confirmed that the phosphorescence materials were considered useful in reducing panic and facilitating a controlled evacuation in the event of a total black-out due to power failure.

  • PDF

Enhancement of Phosphorescence from Organic Fluorescent Materials $Bebq_2$ and $Alq_3$ by Sensitization

  • Tsuboi, Taiju;Jeon, Woo-Sik;Kwon, Jang-Hyuk
    • 한국정보디스플레이학회:학술대회논문집
    • /
    • 2008.10a
    • /
    • pp.1509-1512
    • /
    • 2008

  • Monomer and aggregate of $Bebq_2$ give fluorescence at 492 and 511 nm at 12 K, respectively. Intense T1 emission with vibronic structure was observed from $Bebq_2$ and $Alq_3$ below 70 K by heavily doping with phosphorescent $Ir(ppy)_3$. Energy transfer from $Ir(ppy)_3$ was clarified by photoluminescence excitation spectra.

  • PDF

Development of Fluorescent or Phosphorescent Materials for Non-Dopant Red Organic Light-Emitting Diodes

  • Chen, Chin-Ti
    • 한국정보디스플레이학회:학술대회논문집
    • /
    • 2005.07b
    • /
    • pp.1133-1137
    • /
    • 2005

  • In this paper, a renovated approach in the fabrication of red organic light-emitting diodes (OLEDs) is described. The hard-to-control doping process required for dopant-based red OLEDs can be avoided due to the novel red fluorophores that are not concentration quenching in solid state. Doping is in general a must for phosphorescence OLEDs because of the triplet-triplet annihilation, a common problem for phosphorophore dopants. However, we have recently found that extraordinary red iridium complex showing relatively short emission lifetime render the non-doped phosphorescence red OLED possible.

  • PDF