Photoluminescence intensity

Figure 17.9 (A) Photoluminescence intensity traject07 (gray) of a CdSe-ZnS quantum dot. The high intensity level is the on state and the low intensity level is the off state. The trace in black is the background intensity. Reprinted with permission from reference [14] copyright [2005], American Chemical Society. (B) Schematic...

Figure 17.12 (A) Schematic presentation of deactivation and energy transfer processes in a single quantum dot placed on an Ag nanoparticle film. (B) Photoluminescence intensity trajectories of single quantum dots on a glass substrate (a) and on an Ag nanoparticle film (b). The traces in green represent background intensities. (C) Photoluminescence spectra of quantum dot solutions in the presence of...

Efros, A. L. and Rosen, M. (1997) Random telegraph signal in the photoluminescence intensity of a single quantum dot Phys. Rev. Lett, 78, 1110-1113. 

Precipitation may also be employed in solvents other than water. For example, nanocrystals of ZnS Tb could be prepared by a coprecipitation was effected by addition of aqueous sodium sulfide to Tb(N03)3 and zinc acetate dissolved in methanol.114 ZnS TbF3 and ZnS Eu were prepared similarly. The photoluminescent intensities of the nanocrystals of ZnS Tb and ZnS Eu prepared in this way were 2.5 and 2.8 times stronger than those of bulk (conventionally prepared) phosphors, and these nanocrystals have been proposed for FED, EL, PDP, and CRT applications.114... 

FRET interactions are typically characterized by either steady-state or transient fluorescence emission signals from the donor or acceptor species. Efficient nonradiative energy transfer results in donor PL loss associated with acceptor gain in photoluminescence intensity (if the acceptor is an emitter). The rate of this energy transfer is related to the intrinsic lifetime of the isolated donor and depends strongly on the donor-acceptor separation distance ... 

From photoinduced absorption, luminescence and electron spin resonance observations, the dominant photocarriers generated in the polymer were shown to be polarons and bipolarons [189-191]. It was found that the magnitude of photoinduced absorption is rather independent of the condition of sample preparation whereas the photoluminescence intensity is strongly influenced. The results suggest that the luminescent exciton does not play a primary role in the photogeneration of polaronic species. 

Photoluminescence intensity of the amorphous polymers was generally much larger than that of the more crystalline polymers. The energy level of the lowest singlet excited state Es was evaluated to be 2.5-2.7 eV for the amorphous polymer pristine films, and 2.0 eV for the more crystalline polymers. The Stokes shifts were also observed to be much larger for the amorphous polymer films compared with those of the more crystalline polymer films. This indicates a larger structural relaxation of the amorphous polymers following photoexcitation. 

Importantly, the excited electronic states are not of pure XT vs. CT character, and the observed admixtures of electronic state character strongly depend upon the interface geometry. While the XT states exhibit significantly larger oscillator strength and, hence, photoluminescence intensity, some of the nominal CT states can acquire non-negligible photoluminescence by intensity... 

The photophysical properties of terphenyl-based acyclic (22a) and cyclic hemispherands (22c, 22d, see fig. 27) have been investigated in organic solvents and in KBr pellets (1 wt%) with the purpose of introducing them later in optical amplifiers (Sloofif et al., 1998). Absorption cross sections for the 1.54 pm emission, which is quite broad with fwhh = 70 nm, amount to 0.62, 1.1, and 0.93 x 10 20 cm2 for [Er(22a)], [Er(22c)] and [Er(22d)], respectively. The best photoluminescence intensities are obtained with the cyclic ligands. The optical gain of the complexes doped into a polymer channel waveguide is on the order of 1.7 dB cm-1, while the threshold power is as low as 1.4 mW. 

Figure 19.19 Left side Variation of the photoluminescence intensity E (b) of the PEG-functionalized Au and CdTe nanoparticles depending on the temperature (a) (c) shows the calculated photon-field enhancement factor P of the CdTe nanoparticles as a function of time. Right side Schematic representation of a dynamic nanothermometer based on a nanoparticle superstructure. This superstructure consists of two types of nanoparticles (gold and CdTe) connected by polymeric spacers.118 (Reprinted with permission from J. Lee et al., Angew. Chem. Int. Ed., 2005, 44, 7439-7442. Copyright Wiley-VCH Verlag GmbH Co. KGaA.)...

Figure 3. Hot photoluminescence intensity vs. time from GaAs. The pulse on the left is a calibrating 0.53 pulse arriving at the camera prior to the photoluminescence emission from GaAs.

Voloshin AI, Shavaleev NM, Kazakov VP. Water enhances photoluminescence intensity of europium(III), terbium(III) and samarium(III) tris-P-diketonates in toluene solutions and chemiluminescence intensity of europium(III) and samarium(III) tris-P-diketonates in the reaction with dioxetane. J Photochem Photobiol A Chemistry 2000 136 203-8. 

FIGURE 15 Photoluminescence intensity of rutile Ti02 powder Kanto-R in air with C,-C3 alcohols (methanol, ethanol, 1-propanol, and 2-propanol) as a function of the square root of UV-irradiation time from 1 to 60 s. The squares of the regression coefficients are larger than 0.98. (Reproduced with permission from Nakajima et al. (2002).)... 

Van Derm, R., Fias, R, Driesen, K., et al. (2003) Halogen substitution as an efficient tool to increase the near-infrared photoluminescence intensity of erbium(lll) quinolinates in non-deuterated DMSO. Physical Chemistry Chemical Physics, 5, 2754. 

When the intensity of the excitation Ught and the concentration of the emitting species are kept constant, the photoluminescence intensity is proportional to the concentration of the excited species. 

The passivation of III -V compounds remains a challenging problem for microelectronics but has still received no answer as efficient as the H-termination of Si. The increase of the photoluminescence intensity and lifetime after treatments in sulfide solutions have recently attracted much attention [67]. Dagata et al. [160] have compared, by STM/STS in the ambient atmosphere, the passivation of GaAs in (NH4)2S... 

The presence of oxygen is critical because the interaction of oxygen with the sample can cause serious errors, and its ability to quench not only the fluorescence but also phosphorescence makes deaeration necessary. Also, the photoluminescence intensity usually decreases when the temperature of the sample is increased this is attributed to the higher probability for other nonradiative deactivations in the excited state of the molecule. Therefore, to minimize such temperature effects, the photoluminescence spectra are often measured at liquid-nitrogen temperature and even liquid-helium temperature (33, 34, 36-38, 49-53). 

Fig. 52. Effect of additive ionization potentials on the pliotoluminescence intensity ( ) and the rate R) of the photocatalytic hydrogenation of the added unsaturated hychocarbons with H2O on TiOi (O). /q and are maximum photoluminescence intensities, respectively, under vacuum (or in Ni) and in the presence of added compounds 1, 1,3-butadiene 2, 1-butylene 3, propylene 4,1-butyne 5,1-propyne 6, ethylene 7, acetylene. Photoluminescence spectra recorded at 77 K photocatalytic reactions carried out at 298 K [reproduced with permission from Anpo el al. (223)].

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