CdSe/ZnS quantum dots

Figure 17.7 Schematic illustration of the decay routes of an exciton generated in CdSe-ZnS quantum dots Reprinted with permission from reference [31] copyright [2003], American Chemical Society.

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...

Uematsu, T., Maenosono, S. and Yamaguchi, Y. (2006) Photoinduced fluorescence enhancement in CdSe/ZnS quantum dot monolayers Influence of substrate. Appl. Phys. Lett., 89, 031910. 

Matsumoto, Y, Kanemoto, R Itoh, T, Nakanishi, S Ishikawa, M. and Biju, V. (2008) Photoluminescence quenching and intensity fluctuations of CdSe-ZnS quantum dots on an Ag nanopartide film. /. Phys. Chem. C, 112, 1345-1350. 

Clarke, S. J., Hollmann, C. A., Aldaye, F. A. and Nadeau, J. L. (2008). Effect of ligand density on the spectral, physical, and biological characteristics of CdSe/ZnS quantum dots. Bioconjug. Chem. 19, 562-8. 

Clapp, A.R., Goldman, E.R., and Mattoussi, H. (2006) Capping of CdSe-ZnS quantum dots with DF1LA and subsequent conjugation with proteins. Nat. Protoc. 1(3), 1258-1266. 

Nairn T (2005) Phase-transfer of CdSe ZnS quantum dots using amphiphilic hyperbranched polyethylenimine. Chem Commun 1735-1736... 

Fig. 9.21 In vivo images of MWCNTs-QDs (0.5 tg ml-1 in PBS) in mice injected at different body regions a) MWCNTs attached with CdSe/Zns quantum dots (emission of 600 nm) at middorsal location b) MWCNTs attached with CdSe/ZnS quantum dots at ventrolateral locations, the suspensions were diluted by PBS at various concentrations as indicated (A through E) c) MWCNTs attached with InGaP/ZnS quantum dots (emission of 680 nm, 0.25 jj,g ml-1 in PBS) in liver, kidney, and leg muscles. All images were taken successfully in 2 min under epi-UV illuminator with excitation of 435nm. (Shi et al. 2007). Published with permission from Wiley-VCH see Color Plates)...

Goldman, E. R., I. L. Medintz, A. Hayhurst, G. P. Anderson, J. M. Mauro, B. L Iverson, G. Georgiou, and H. Mattoussi. Self-assembled luminescent CdSe-ZnS quantum dot bioconjugates prepared using engineered poly-histidine terminated proteins. Anal. Chim. Acta 534, 63-67 (2005). 

Mattoussi H, Mauro JM, Goldman ER, Anderson CP, Sundar VC, Mikulec FV, Bawen-di MG (2000) Self-assembly of CdSe-ZnS quantum dot bioconjugates using an engineered recombinant protein. J Am Chem Soc 122 12142-12150... 

Figure 11.3 Brightness comparison for tetramethylrhodamine isothiocyanate (TRITC), TRITC-doped silica nanoparticles (20 nm), and CdSe/ZnS quantum dots (28 nm diameter).27 (Reprinted with permission from H. Ow et al., Nano Lett., 2005, 5, 113-117. Copyright 2005 American Chemical Society.)...

Other approaches already realized include the development of a simple and rapid method for spironolactone determination based on the quenching of the fluorescence of CdSe quantum dots by the analyte52 or the determination of anthracene with a detection limit of 1.6 x 10-8 M based on the quenching effect of this polycyclic aromatic hydrocarbon on water-soluble CdSe/ZnS quantum dots, prepared via a simple sonochemical procedure using (3-cyclodextrin ((3-CD) as surface coating agent.53... 

Chen C-Y, Cheng C-T, Lai C-W, et al. Potassium ion recognition by 15-crown-5 functionalized CdSe/ZnS quantum dots in H2Q. Chem Commun 2006 263-5. 

Algar, W. R., and Krull, U. J. (2006), Adsorption and hybridization of oligonucleotides on mercaptoacetic acid-capped CdSe/ZnS quantum dots and quantum dot-oligonucleotide conjugates, Langmuir, 22,11346-11352. 

Highly ordered triangular-shaped (1) CdSe/ZnS quantum dots PMMA matrix Pompaetal. (2006) ... 

Song, J. -H., Atay, T., Shi, S., Urabe, H., and Nurmikko, A. V. (2005). Large enhancement of fluorescence efficiency from CdSe / ZnS Quantum Dots induced by resonant coupling to spatially controlled surface plasmons. Nano Lett 5, 8 1557-1561. 

NON-FRET EMISSION QUENCHING AND ELECTRON WAVE FUNCTION TUNNELING IN EXCITED NANOCOMPOSITES CdSe/ZnS QUANTUM DOTS - PORPHYRINS ... 

The photoluminescence quenching of semiconductor CdSe/ZnS quantum dots (QDs) caused by suifacely attached porphyrins increases with QDs size decrease. Porphyrin-QD interaction induces a pertubation of the excitonic wave function leading to a net charge localisation of the electron-hole pair accompanied by an increase of radiationless decay rates being proportional to the calculated radial probability of the confined exciton wave function at QD surface. 

Presented experimental data reveal that for CdSe/ZnS quantum dots with two ZnS monolayers values follow a monotonous function drastically decaying with the QD core diameter. From the physico-chemical point of view, we conjecture that upon interaction of P with QD surface, the electron wave function may be locally modified (via inductive and/or mesomeric effects [9]) forming a surface local state capable to trap the electron of the photogenerated exciton (Fig. 2A). Thus, we will consider the behaviour of the electron wave function at the interface to the functional pyridyl group of the attached porphyrin. The single-carrier envelope wave functions y/a in a spherical core/shell QD are determined by the Schrodinger equation... 

Non-FRET emission quenching and electron wave function tunneling in excited nanocomposites CdSe/ZnS quantum dots-porphyrins 144... 

Wang, D., He, J., Rosenzweig, N. and Rosenzweig, Z. (2004) Superparamagnetic Fe203 beads-CdSe/ZnS quantum dots core-shell nanocomposite particles for cell separation. Nano Lett., 4, 409—413. 

EVOLUTION OF OPTICAL PHONONS IN CdSe/ZnS QUANTUM DOTS RAMAN SPECTROSCOPY... 

Finally, at a ZnS thickness of 2ML the surface of the CdSe core is mainly defect free although the structure of the shell is not established yet. It occins at the thickness more than 3.4 ML where the shell is, most likely, amorphous. It is interesting to note that peak of the PL quantum )deld of the analogous CdSe/ZnS quantum dots has been observed at a ZnS thickness in the range of 1.7 ML [1]. Probably, the defect-free core shell interface is more important for getting highly-luminescent QD structures than the increase of the shell thickness. 

STRUCTURE AND EXCITED STATE PROPERTIES OF CdSe/ZnS QUANTUM DOT-PORPHYRIN COMPLEXES FORMED BY SUPRAMOLECULAR DESIGN... 

Self-assembly principles of the formation of multiporphyrin arrays are extended to anchor the porphyrin triads on semiconductor CdSe/ZnS quantum dot (QD) surface. Comparing with individual counterparts (QD, pyridylsubstituted porphyrin H2P(p-Pyr)4, and Zn-octaethylporphyrin chemical dimer (ZnOEP Ph), the formation of heterocomposites QD-porphyrin triad results in the specific quenching of QD photoluminescence, accompanied by the dimer fluorescence strong quenching (Tsd 1-7 ps due to energy and/or electron transfer) and the noticeable decease of the extra-ligand H2P(p-Pyr)4 fluorescence efficiency by 1.5-2 times via hole transfer H2P—>dimer. 

SLOWING DOWN OF INTRABAND RELAXATION OF CdSe/ZnS QUANTUM DOTS AT HIGH DENSITY OF THE EXCITED CARRIERS... 

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