Photoluminescence , spectra

Photoluminescent spectra for methyltetrahydrofolate and the enzyme methyltransferase. When methyltetrahydrofolate and methyltransferase are mixed, the enzyme is no longer photoluminescent, but the photoluminescence of methyltetrahydrofolate is enhanced. (Spectra courtesy of Dave Roberts, DePauw University.)... 

The electroluminescence spectra of the single-layer devices are depicted in Figure 16-40. For all these OPV5s, EL spectra coincided with the solid-state photoluminescence spectra, indicating that the same excited states are involved in both PL and EL. The broad luminescence spectrum for Ooct-OPV5-CN" is attributed to excimer emission (Section 16.3.1.4). 

For the three oclyloxy-subslitulcd five-ring oligomers, the normalized photoluminescence spectra of the single crystals are depicted in Figure 16-26. Due to the large absorption coefficient (more than 105 cm"1 at the maximum) we were not able to measure the absorption spectra of the relatively thick (20-30 pm) single crystals (see Table 16-5 in Section 16.3.3.3.1). 

Fig. 2. Photoluminescence spectra of the methyl-substituted Me-LPPP (29) (solid line solid state dashed line solution, methylene chloride)...

FIG. 14 Measurements on monolayers and LB films of CdSe nanoparticles of narrow size distribution (a) II-A isotherms for Langmuir monolayers of CdSe nanoparticles of diameter 2.5 run (curve a), 3.0 mn (curve b), 3.6 mn (curve c), 4.3 mn (curve d), and 5.3 mn (curve e). The area per nanoparticle was determined by dividing the trough area by the estimated number of particles deposited on the surface, (b) Absorbance and photoluminescence spectra of the nanoparticles in solution (A, B) and in monolayers on sulfonated polystyrene-coated glass sbdes (C. D). The nanoparticle diameters are 2.5 nm (curves labeled a), 3.6 nm (curves labeled b), and 5.3 nm (curves labeled c). The excitation wavelengths are (a) 430 nm, (b) 490 nm, and (c) 540 nm. (Reproduced with permission from Ref. 158. Copyright 1994 American Chemical Society.)... 

Figure 17.2 (A) Absorption and photoluminescence spectra of CdSe quantum dots prepared from CdO, CdC03, and Cd(AcO)2 in the presence of different ligands. (B) Increase in the optical density (at 400 nm) of a CdSe quantum dot reaction mixture with time under reaction at 75 "C. Color pictures in the inset of B represent CdSe (a,b) andCdSe-ZnS (c) quantum...

In addition to the photoluminescence red shifts, broadening of photoluminescence spectra and decrease in the photoluminescence quantum efficiency are reported with increasing temperature. The spectral broadening is due to scattering by coupling of excitons with acoustic and LO phonons [22]. The decrease in the photoluminescence quantum efficiency is due to non-radiative relaxation from the thermally activated state. The Stark effect also produces photoluminescence spectral shifts in CdSe quantum dots [23]. Large red shifts up to 75 meV are reported in the photoluminescence spectra of CdSe quantum dots under an applied electric field of 350 kVcm . Here, the applied electric field decreases or cancels a component in the excited state dipole that is parallel to the applied field the excited state dipole is contributed by the charge carriers present on the surface of the quantum dots. 

Figure 17.4 (A) Photoluminescence spectral shifts (AX,) of a solution of CdSe quantum dot aggregates during heating-cooling cycles photoluminescence spectral maxima were recorded at 298 K during cooling and 353 K during heating. Reversibility of the photoluminescence spectral shift was attained after four heating-cooling cycles. (B) Photoluminescence spectra of a solution ofCdSe...

Figure 17.8 (A) Photoluminescence spectra of CdSe quantum dots in CHCI3 in the presence of polybutadiene at different times under photoactivation at 400 nm. The blue shift of the photoluminescence spectra is due to a gradual decrease in quantum dot size. (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...

FIG. 20 23 Normalized photoluminescence spectra of 3.1-um ( excitation = 320 nm) and4.2-nm (Xexdtation = 340 nm) Ge nanoparticles dispersed in chloroform at 25 C with quantum yields of 6.6 and 4.6 percent, respectively. [Reprinted with permission from Lu et al. Nano Lett, 4(5), 969-974 (2004). Copyright 2004 American Chemical Society. ]... 

FIG. 77. Room-temperature photoluminescence spectra of Er-implanted PECVDa-Si H, annealed at 400°C. The implantation energy and dose were 125 keV and 4 x 10 Er/cm". respectively, which resulted in peak concentration of 0.2 at.%. "Low-0" and "high-O" denote a peak oxygen concentration in a-Si H of 0.3 and 1.3 at.9c. respectively. The inset shows the 1.54-/im peak intensity as a function of annealing temperature, for both oxygen concentrations. (From J. H. Shin. R. Serna, G. N. van den Hoven, A. Polman, W. G. J. H. M. van Sark, and A. M. Vredenberg. Appl. Phys. Lett. 68. 697 (1996). 1996, American Institute of Physics, with permission.]... 

Fig. 19 (a) Optical absorption and (b) photoluminescence spectra of CdSe and CdSe QDs capped with different concentration of cytosine. Sample A is as-prepared QDs and Samples B and C are capped QDs. (Adapted from [75])... 

Fig. 17 Photoluminescence spectra covering the no-phonon and TA phonon-replica energy regions taken at 4.2 K. The spectra show the bound exciton luminescence of samples implanted with B, In, and T1 before (a, c, e) and after (b, d, f) treatment in atomic H. Bound exciton luminescence due to the implanted impurities has been shaded in to distinguish it from the substrate luminescence. From Thewalt et al. (1985).

The introduction of electronic deep levels is demonstrated in Fig. 9 with low-temperature photoluminescence spectra for n-type (P doped, 8 Cl cm) silicon before (control) and after hydrogenation (Johnson et al., 1987a). The spectrum for the control sample is dominated by luminescence peaks that arise from the well-documented annihilation of donor-bound excitons (Dean et al., 1967). After hydrogenation with a remote hydrogen plasma, the spectrum contains several new transitions with the most prominent peaks at approximately 0.95, 0.98, and 1.03 eV. These transitions identify... 

Figure 6.27. Photoluminescence spectra of as-deposited CuInS2 thin films made from an SSP.

Figure 6.28. Photoluminescence spectra of CuInS2 films prior to annealing and after annealing in either S/Ar or Ar flow at 450°C for 7 h for leading edge (left) and trailing edge (right) of the deposited film.

SnS2. Weakly crystalline SnS2 films have been grown from tin(II) chloride and sodium sulfide precursors. EDX analysis gave a Sn/S ratio of 1/2.02. The surface roughness of a 290-nm-thick film was 32 nm. The band gap was 2.22 eV, and the photoluminescence spectra, using a 325 nm excitation source, showed peaks at 549 nm and 700 nm.118... 

When photoluminescence spectra were recorded for a Ti(OSi(CH3)3)4 model compound, upon excitation at 250 nm only one emission band was detected (at 500 nm), which was assigned to a perfect closed Ti(OSi)4 site. The excitation of these species is considered to be a LMCT transition, 02 Ti4+ —<> (0-Ti3+), and the emission is described as a radiative decay process from the charge transfer state to the ground state, O Ti3+ — 02 Ti4+. Soult et al. (94) also observed an emission band at 499 nm, which they attributed to the presence of a long-lived phosphorescent excited state. The emission band at 430 nm of TS-1 was tentatively assigned to a defective open Ti(OSi)3(OH) site (49). 

J Kalinowski, G Giro, M Cocchi, V Fattori, and P DiMarco, Unusual disparity in electroluminescence and photoluminescence spectra of vacuum-evaporated films of 1,1 -bis ((di-4-tolylamino) phenyl) cyclohexane, Appl. Phys. Lett., 76 2352-2354, 2000. 

Fig. 10.5 Photoluminescence spectra of dissolved C6Q. The peak at 750nm is the photoluminescence signature of the material. Photoluminescent C60 aggregates can be visualized within cells and exhibit a vivid red signature which is easily detectable (Levi et al., 2006) (See Color Plates)...

Capozzi V, Trovato T, Berger H, Lorusso GF (1997) Photoluminescence spectra of C-60 thin films deposited on different substrates. Carbon 35 763-766. 

Photo-induced reactions, 32 105-109 Photoluminescent spectra, 31 114-116,119-121,125 Photolysis water, 31 60... 

We will now focus our attention on the photoluminescence process. A typical experimental arrangement to measure photoluminescence spectra is sketched in Figure 1.8. Photoluminescence spectra are also often measured using compact commercial equipment called spectrofluorimeters. Their main elements are also shown in Figure 1.8. 

Figure 1.8 A schematic diagram showing the main elements for measuring photoluminescence spectra. The excitation can also be produced using a laser instead of both a lamp and an excitation monochromator.

Figure 14.2 Evolution of the photoluminescence spectra from the QDs and Cy3 dyes in the QD-MBP-Cy3 assemblies versus increasing dye-to-QD ratio n (a), along with the corresponding fractional donor loss, acceptor enhancement, donor-based efficiency, and a fit of Equation (8) versus n (b). Spectra shown were corrected for direct excitation and deconvoluted. Case of 510 nm emitting QDs is shown. Adapted from reference 28 and reprinted by permission of the American Chemical Society.

Figure 14.3 (a) Evolution of the photoluminescence spectra from 555 nm emitting QDs... 

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