Energy transfer in complexes of water-soluble quantum dots and chlorin e6 molecules in different environments

• Irina V. Martynenko,
• Anna O. Orlova,
• Vladimir G. Maslov,
• Alexander V. Baranov,
• Anatoly V. Fedorov and
• Mikhail Artemyev

Beilstein J. Nanotechnol. 2013, 4, 895–902, doi:10.3762/bjnano.4.101

• extinction coefficient and high quantum yield of photoluminescence with the wavelength controlled by the QD size. It is very attractive to use QDs as an energy donor in complexes with organic molecules since the conditions for an effective FRET can be quite easily satisfied. For effective functioning of

• , since the decrease in PL quantum yield (QY) of the tetrapyrroles is usually accompanied by a decrease in efficiency of singlet oxygen generation [4]. In this study we investigate the photophysical properties of QD–Ce6 complexes under variable conditions of formation such as the molar concentration ratio

• equation: In this equation, Φ2 is the orientation factor, Φ0D is the quantum yield of the donor in the absence of quencher; N is the Avogadro number and ns is the refractive index of the solvent. I is the overlap integral between the donor emission band and the acceptor absorption band: where is the

Modulation of defect-mediated energy transfer from ZnO nanoparticles for the photocatalytic degradation of bilirubin

• Tanujjal Bora,
• Karthik K. Lakshman,
• Soumik Sarkar,
• Abhinandan Makhal,
• Samim Sardar,
• Samir K. Pal and
• Joydeep Dutta

Beilstein J. Nanotechnol. 2013, 4, 714–725, doi:10.3762/bjnano.4.81

• vacancies exist in three charged states: singly charged (VO+), doubly charged (VO++) and neutral (VOx). The presence of the oxygen vacancies and other native defects in the ZnO lattice reduces the direct e−/h+ recombination process and thus increases the quantum yield of ZnO nanocrystalline photocatalysts

Apertureless scanning near-field optical microscopy of sparsely labeled tobacco mosaic viruses and the intermediate filament desmin

• Alexander Harder,
• Mareike Dieding,
• Volker Walhorn,
• Sven Degenhard,
• Andreas Brodehl,
• Christina Wege,
• Hendrik Milting and
• Dario Anselmetti

Beilstein J. Nanotechnol. 2013, 4, 510–516, doi:10.3762/bjnano.4.60

• facilitates the alignment relative to the illumination laser. As fluorescent dye we used maleimide-modified Atto740 (Atto-Tec, Siegen, Germany) which has a remarkable photo-stability and a preferably low quantum yield of 10%. Low quantum efficiencies are beneficial as dipole–dipole coupling effects between

• the cantilever tip and dye increase the radiative decay rate and thus enhance the quantum yield [34]. Sample preparation The desmin protein was expressed in E.coli, isolated and purified as reported recently [20]. Desmin monomers expose a single cysteine, which is an ideal anchor for dye attachment

Selective surface modification of lithographic silicon oxide nanostructures by organofunctional silanes

• Thomas Baumgärtel,
• Christian von Borczyskowski and
• Harald Graaf

Beilstein J. Nanotechnol. 2013, 4, 218–226, doi:10.3762/bjnano.4.22

• fluorescence signal is comparably weak (roughly a factor of 10 above the background noise level). The main reason for this is the quenching by the underlying silicon. Nevertheless, other high-quantum-yield xanthene dyes (e.g., rhodamine 6G) that are bound to the nanostructures by electrostatic interactions

Distance dependence of near-field fluorescence enhancement and quenching of single quantum dots

• Volker Walhorn,
• Jan Paskarbeit,
• Heinrich Gotthard Frey,
• Alexander Harder and
• Dario Anselmetti

Beilstein J. Nanotechnol. 2011, 2, 645–652, doi:10.3762/bjnano.2.68

• single dipole emitter that is oriented perpendicular to the sample surface was estimated for several tip distances. Secondly, to evaluate the relative quantum yield Q (Equation 3), one has to separate the impact of the coupling between the dipole emitter and the tip apex from that of the secondary fields

• the quotient of the corresponding field intensities at the location of the fluorophore. Accordingly, we define the relative emission rate Γem (Equation 3) of a single fluorophore by the product of Γexc and relative quantum yield Q. where q and q0 are the apparent and intrinsic quantum yield

• , respectively. Generally, the shift of the quantum yield can be described in terms of the radiative and nonradiative decay rates (γr, γnr) as follows: The coupling between a dipole emitter and a sharp metallic tip results in an increase of γr [32][35]. Yet, the degree of luminescence enhancement is inherently

Room temperature excitation spectroscopy of single quantum dots

• Christian Blum,
• Frank Schleifenbaum,
• Martijn Stopel,
• Sébastien Peter,
• Marcus Sackrow,
• Vinod Subramaniam and
• Alfred J. Meixner

Beilstein J. Nanotechnol. 2011, 2, 516–524, doi:10.3762/bjnano.2.56

• different timescales, we see no significant differences between the single quantum dots or distinct individual features in this part of the spectrum. In general, observed wavelength dependent changes in photoluminescence can result from changes in either the absorbance or the photoluminescence quantum yield

• performed [52]. This result implies that the photoluminescence quantum yield in CdSe quantum dot ensembles is independent of the excitation wavelength, and that analyzing the excitation spectra also allows one to draw conclusions about the absorbance spectra of single quantum dots. Following from this, the

Towards multiple readout application of plasmonic arrays

• Dana Cialla,
• Karina Weber,
• René Böhme,
• Uwe Hübner,
• Henrik Schneidewind,
• Matthias Zeisberger,
• Roland Mattheis,
• Robert Möller and
• Jürgen Popp

Beilstein J. Nanotechnol. 2011, 2, 501–508, doi:10.3762/bjnano.2.54

• sample 1 and 2 for fluorescence measurements of Cy3.5. A further contribution to SEF is described as an enhanced decay rate that improves the quantum yield of the fluorophore and decreases the lifetime, which should allow the fluorophore to undergo more excitation–de-excitation cycles before

Fabrication and spectroscopic studies on highly luminescent CdSe/CdS nanorod polymer composites

• Jana Bomm,
• Andreas Büchtemann,
• Angela Fiore,
• Liberato Manna,
• James H. Nelson,
• Diana Hill and
• Wilfried G. J. H. M. van Sark

Beilstein J. Nanotechnol. 2010, 1, 94–100, doi:10.3762/bjnano.1.11

• . Keywords: CdSe; luminescence lifetime; nanocomposites; nanorods; quantum yield; Introduction Semiconductor nanoparticles have attracted great interest in recent years because of their fascinating optical properties. Their emission wavelength can be tuned directly by changing their size and shape as a

• QE of 70% (for a NR concentration of 0.05 wt %). The PL QE in solution measured at 395 nm for an aspect ratio of 6 nanorods was 70%, which means no luminescence quenching occurred in the P(LMA-co-EGDM) nanocomposites. To our knowledge this is the highest luminescence quantum yield ever reached in a

• excitation wavelength of 395 nm with a Hamamatsu absolute PL quantum yield measurement system C9920-02, which uses an integrating sphere. Luminescence lifetime measurements were performed in a setup containing a FLS920 flourimeter (Edinburgh Instruments, Livingston, UK). A supercontinuum whitelight source