The influence of phthalocyanine aggregation in complexes with CdSe/ZnS quantum dots on the photophysical properties of the complexes

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

Beilstein J. Nanotechnol. 2016, 7, 1018–1027, doi:10.3762/bjnano.7.94

• energy donor in QD/tetrapyrrole complexes because of their unique optical properties. QDs exhibit an extremely high extinction over a broad spectral range and a high quantum yield (QY) of photoluminescence (PL) [12][13][14]. In addition, the emission properties of QDs can be tuned through the size of the

• aqueous solution. Previously [27], we found that a reduction in the intracomplex FRET and phthalocyanine molecule PL quantum yield was observed with increase in the PcSz concentration in the mixture. We show in this paper that aggregation of PcSz molecules leads to a concentration dependence of the

• the quantum yield of PcSz and of the efficiency of energy transfer in complexes with an increasing number of PcSz molecules per quantum dot. It is evident that increasing the concentration of PcSz in our samples lead to a decrease of PL of PcSz because of nonluminescent PcSz aggregates in the

Facile synthesis of water-soluble carbon nano-onions under alkaline conditions

• Gaber Hashem Gaber Ahmed,
• Rosana Badía Laíño,
• Josefa Angela García Calzón and
• Marta Elena Díaz García

Beilstein J. Nanotechnol. 2016, 7, 758–766, doi:10.3762/bjnano.7.67

• quantum yield of C-dots excited at 362 nm resulted to be 1.32% while that of C-onions excited at 328 nm was 1.63%. These values were similar or even higher than those obtained for carbon dots prepared by the same route of synthesis using different starting materials (Table S1, Supporting Information File

• solution (so that the total concentration of metal was 10 ppm) and then adjusting the volume to 5 mL with a universal buffer solution pH 6 (0.2 M Na2HPO4/0.1 M citric acid). The PL was measured as mentioned above with the same instrumental settings. A 1 cm quartz cuvette was used. PL quantum yield

• measurement The PL quantum yield was calculated through the well-established comparative method using quinine sulfate as a reference. The following equations were used in the quantum yield measurement: where is the quantum yield, F is the calculated integrated luminescence intensity, n is the refractive

Fabrication and properties of luminescence polymer composites with erbium/ytterbium oxides and gold nanoparticles

• Julia A. Burunkova,
• Ihor Yu. Denisiuk,
• Dmitri I. Zhuk,
• Lajos Daroczi,
• Attila Csik,
• István Csarnovics and
• Sándor Kokenyesi

Beilstein J. Nanotechnol. 2016, 7, 630–636, doi:10.3762/bjnano.7.55

• , which fill the volume of the composite rather uniformly because of our synthesis technology, and the gold nanoparticles are also attached there, the plasmon field of excited AuNPs can enhance the quantum yield of luminescence. Of course, they should be separated by 5–10 nm, to prevent tunneling of the

Green and energy-efficient methods for the production of metallic nanoparticles

• Mitra Naghdi,
• Mehrdad Taheran,
• Satinder K. Brar,
• M. Verma,
• R. Y. Surampalli and
• J. R. Valero

Beilstein J. Nanotechnol. 2015, 6, 2354–2376, doi:10.3762/bjnano.6.243

Light-powered, artificial molecular pumps: a minimalistic approach

• Giulio Ragazzon,
• Massimo Baroncini,
• Serena Silvi,
• Margherita Venturi and
• Alberto Credi

Beilstein J. Nanotechnol. 2015, 6, 2096–2104, doi:10.3762/bjnano.6.214

• ring or not. For example, the photostationary cis/trans ratio upon 365 nm irradiation is slightly larger for the complex than for the free axle, which means that K2,hν > K4,hν. On the other hand, we observed that the photoisomerization quantum yield values are the same for the free and complexed axle

• . Irradiation of the ring–axle mixture at 287 nm generates a photostationary state with a larger cis/trans ratio than for the axle alone (K2,hν > K4,hν), as discussed above for excitation at 365 nm. Also, upon irradiation at 287 nm, the photoisomerization quantum yield of the axle is not affected by the

A facile method for the preparation of bifunctional Mn:ZnS/ZnS/Fe₃O₄ magnetic and fluorescent nanocrystals

• Houcine Labiadh,
• Tahar Ben Chaabane,
• Romain Sibille,
• Lavinia Balan and
• Raphaël Schneider

Beilstein J. Nanotechnol. 2015, 6, 1743–1751, doi:10.3762/bjnano.6.178

• → 6A1 Mn2+ transition. The PL quantum yield (QY) and the remnant magnetization can be regulated by varying the thickness of the magnetic shell. The results showed that an increase in the thickness of the Fe3O4 magnetite layer around the Mn:ZnS/ZnS core reduced the PL QY but improved the magnetic

• , QDs possess many advantages, including a broad absorption with a narrow photoluminescence (PL) spectra, low photobleaching, high PL quantum yield (QY), tunable emission from the visible to infrared wavelengths, and high resistance to chemical degradation [3][4]. Such characteristics originate from

• luminescence efficiency, and vice versa. The Mn:ZnS/ZnS/Fe3O4 (1) sample, which exhibited the best fluorescence quantum yield, also exhibited limited magnetic characteristics. Nevertheless, samples Mn:ZnS/ZnS/Fe3O4 (1.5) and Mn:ZnS/ZnS/Fe3O4 (2) are a good compromise to maintain both fluorescence and magnetic

Addition of Zn during the phosphine-based synthesis of indium phospide quantum dots: doping and surface passivation

• Natalia E. Mordvinova,
• Alexander A. Vinokurov,
• Oleg I. Lebedev,
• Tatiana A. Kuznetsova and
• Sergey G. Dorofeev

Beilstein J. Nanotechnol. 2015, 6, 1237–1246, doi:10.3762/bjnano.6.127

• luminescence quantum yield through the reduction of phosphorous dangling bonds. A scenario for the growth of the colloidal InP(Zn) QDs was proposed and discussed. Keywords: core–shell nanoparticles; doped semiconductor nanocrystals; InP(Zn) quantum dots; luminescence; zinc; Introduction Colloidal quantum

• described here (Figure 6). Usually, non-doped QDs exhibit very low PL efficiencies immediately after preparation, i.e. the quantum yield (QY) is below 0.5%. This is because of the numerous dangling bonds present on the surface of the QDs. QY slightly increases up to 1–2% due to the oxidation of the

Electronic interaction in composites of a conjugated polymer and carbon nanotubes: first-principles calculation and photophysical approaches

• Florian Massuyeau,
• Jany Wéry,
• Jean-Luc Duvail,
• Serge Lefrant,
• Abu Yaya,
• Chris Ewels and
• Eric Faulques

Beilstein J. Nanotechnol. 2015, 6, 1138–1144, doi:10.3762/bjnano.6.115

• sensitivity Keithley electrometer. Figure 1 compares photoconductivity (PC) data and quantum yield estimates for the composite PPV/SWNT series x = 0–32%. We observe that the quantum yield decreases from a value of 19% (x = 0, standard PPV) in good agreement with the literature [19][20] down to 4% for x = 32

• approach assumes that the radiative and non-radiative lifetimes τr, τnr can be expressed as a function of the PL quantum yield Q, , . τnr accounts for phonon emission, intersystem crossing to triplet states, trapping at chemical defects and exciton migration/dissociation. For standard PPV (x = 0%) we find

Charge carrier mobility and electronic properties of Al(Op)₃: impact of excimer formation

• Andrea Magri,
• Pascal Friederich,
• Bernhard Schäfer,
• Valeria Fattori,
• Xiangnan Sun,
• Timo Strunk,
• Velimir Meded,
• Luis E. Hueso,
• Wolfgang Wenzel and
• Mario Ruben

Beilstein J. Nanotechnol. 2015, 6, 1107–1115, doi:10.3762/bjnano.6.112

• photophysical properties in solution and in thin film are summarized in Table 1 and are consistent with excimer formation. In more detail, Al(Op)3 in solution is characterized by a photoluminescence quantum yield (Φ) of 0.027 and a lifetime (τ) of 0.7 ns. In the form of a thin film, the quantum yield (Φ) is

• calculate the corrected redox potential. Absorption and emission spectra were acquired at room temperature for diluted CH2Cl2 solutions (8.0 × 10−6 M) on a Cary 500 Scan UV–vis–NIR spectrophotometer and a Cary Eclipse fluorescence spectrophotometer using a 1 cm quartz cell. The photoluminescence quantum

• yield was computed using rhodamine 6G as reference [42][43]. Characterization in thin film The evaporation of the samples on quartz substrates was carried out using an Edwards Auto 306 evaporator equipped with a high vacuum chamber (10−6 mbar) and a frequency thickness monitor (FTM) to check the

Novel ZnO:Ag nanocomposites induce significant oxidative stress in human fibroblast malignant melanoma (Ht144) cells

• Syeda Arooj,
• Samina Nazir,
• Akhtar Nadhman,
• Nafees Ahmad,
• Bakhtiar Muhammad,
• Ishaq Ahmad,
• Kehkashan Mazhar and
• Rashda Abbasi

Beilstein J. Nanotechnol. 2015, 6, 570–582, doi:10.3762/bjnano.6.59

• a period of time. The natural logarithm values of absorption of DPBF were calculated to show an increase in the amount of 1O2. As shown in Figure 6, the samples with only DPBF (quantum yield ΦΔ = 0.043 ± 0.02) had a slight increase in the 1O2 production, which represents the baseline 1O2 release by

• rate of the photosensitized process. The 1O2 quantum yield of the nanoparticles in aqueous solution was calculated using MB as a standard by the following formula: is the 1O2 quantum yield of the nanoparticles, is the 1O2 quantum yield of MB that was calculated by using Rose Bengal (RB) as a

• twice with triplicates of each sample. Consumptions of the singlet oxygen indicator DPBF mixed with ZnO and ZnO:Ag nanocomposites under the exposure to light and recorded every 30 s. (a) Time course of the natural log of absorption spectrum of DPBF at 410 nm. (b) Quantum yield (mean ± SD) of singlet

Silica micro/nanospheres for theranostics: from bimodal MRI and fluorescent imaging probes to cancer therapy

• Shanka Walia and
• Amitabha Acharya

Beilstein J. Nanotechnol. 2015, 6, 546–558, doi:10.3762/bjnano.6.57

• ions Gd3+ and Eu3+/Tb3+ inside silica NPs through Stöber’s process. In addition, the silica spheres were modified with a pyridine–based aromatic linkage which in turn was found to increase the quantum yield emission of Eu3+/Tb3+ ions present inside the silica shell. The silica NPs grafted with 3

Carrier multiplication in silicon nanocrystals: ab initio results

• Ivan Marri,
• Marco Govoni and
• Stefano Ossicini

Beilstein J. Nanotechnol. 2015, 6, 343–352, doi:10.3762/bjnano.6.33

• . Experimental results were interpreted by hypothesizing a direct formation of e–h pairs localized onto different NCs by SSQC. The measured quantum yield was proven to be very similar to that measured in the PL experiments conducted by Timmerman et al. [33][34][35], pointing to a similar microscopic origin of

Overview about the localization of nanoparticles in tissue and cellular context by different imaging techniques

• Anja Ostrowski,
• Daniel Nordmeyer,
• Alexander Boreham,
• Cornelia Holzhausen,
• Lars Mundhenk,
• Christina Graf,
• Martina C. Meinke,
• Annika Vogt,
• Sabrina Hadam,
• Jürgen Lademann,
• Eckart Rühl,
• Ulrike Alexiev and
• Achim D. Gruber

Beilstein J. Nanotechnol. 2015, 6, 263–280, doi:10.3762/bjnano.6.25

• undergo photobleaching, photoactivation is a remarkable property of QD enhancing their quantum yield over time [90]. Another group of highly photostable NP are lanthanide-doped upconversion NP (UCNP). Upconversion is an optical process in which the sequential absorption of two or more photons leads to the

Poly(styrene)/oligo(fluorene)-intercalated fluoromica hybrids: synthesis, characterization and self-assembly

• Giuseppe Leone,
• Francesco Galeotti,
• William Porzio,
• Guido Scavia,
• Luisa Barba,
• Gianmichele Arrighetti,
• Giovanni Ricci,
• Chiara Botta and
• Umberto Giovanella

Beilstein J. Nanotechnol. 2014, 5, 2450–2458, doi:10.3762/bjnano.5.254

• similar to neat TF, in turn unchanged compared to the terfluorene [26], with vibronic side bands typical of fluorene-based oligomers. The PL intensity of PT15 film is higher than PT5 and PT30 likely due to the higher density of fluorescent intercalated tactoids. We recorded a PL quantum yield of 48% for

Inorganic Janus particles for biomedical applications

• Isabel Schick,
• Steffen Lorenz,
• Dominik Gehrig,
• Stefan Tenzer,
• Wiebke Storck,
• Karl Fischer,
• Dennis Strand,
• Frédéric Laquai and
• Wolfgang Tremel

Beilstein J. Nanotechnol. 2014, 5, 2346–2362, doi:10.3762/bjnano.5.244

• yield governed by the electronic passivation of the surface, whereas the quantum yield was decreased for a shell thickness of more than two multilayers, which was attributed to lattice imperfections within the shell (Figure 2c) [13]. Recent developments in the fields of hetero-structured quantum dots

• exploration of their physicochemical properties and large scale applications in the near future. Illustrations of the transition from isotropic to anisotropic particles. a) Evolution of the PL-peak position, b) schematic representation, and c) evolution of the PL-quantum yield for several core-shell quantum

• by using the successive ion layer adhesion and reaction (SILAR) technique (Figure 2b). Upon the gradual change of the composition in radial direction, a bathochromic shift of the photoluminescence-band was observed due to the reduced confinement (Figure 2a). This goes along with the enhanced quantum

Data-adaptive image-denoising for detecting and quantifying nanoparticle entry in mucosal tissues through intravital 2-photon microscopy

• Torsten Bölke,
• Lisa Krapf,
• Regina Orzekowsky-Schroeder,
• Tobias Vossmeyer,
• Jelena Dimitrijevic,
• Horst Weller,
• Anna Schüth,
• Antje Klinger,
• Gereon Hüttmann and
• Andreas Gebert

Beilstein J. Nanotechnol. 2014, 5, 2016–2025, doi:10.3762/bjnano.5.210

• a hydrodynamic diameter of ca. 25 nm, as determined by dynamic light scattering (DLS). The spectral position of the excitonic emission band was located at ca. 585 nm (FWHM: ca. 32 nm), and the photoluminescence quantum yield was around 20–30%. Setup of the 2-photon microscope Intravital 2PM was done

Carbon nano-onions (multi-layer fullerenes): chemistry and applications

• Juergen Bartelmess and
• Silvia Giordani

Beilstein J. Nanotechnol. 2014, 5, 1980–1998, doi:10.3762/bjnano.5.207

• nm. In addition, steady-state absorption and fluorescence spectroscopy was performed. It was found that the functionalized CNOs exhibit a distinct CNO-centered, excitation-wavelength-dependent fluorescence with a fluorescence quantum yield of 0.08. The fluorescence lifetimes depended on the emission

Synthesis of hydrophobic photoluminescent carbon nanodots by using L-tyrosine and citric acid through a thermal oxidation route

• Venkatesh Gude

Beilstein J. Nanotechnol. 2014, 5, 1513–1522, doi:10.3762/bjnano.5.164

• required. The emission quantum yield of the TCND-1 solution was found to be found approximately (3.8%) by using anthracene in ethanol at 340 nm excitation wavelength as reference (Figure S2, Supporting Information File 1). The reason for such a low quantum yield of the TCND-1 solution are the different

• nanoparticle mixture it was found that the fractionated CNDs exhibited a 5–6 times higher quantum yield than the unfractionated CNDs mixture. The reported results by Vinci et al. suggested that some components (absorbing species) present in the mixture did not exhibit photoluminescence and suppressed the

• quantum yield of the mixture of CNDs [37]. Another interesting optical property of these tyrosine-passivated CNDs is upconversion photoluminescence (UCPL) when irradiated with wavelengths above 500 nm, which is very important for applications as photocatalyst and for light harvesting applications [2][5

Nano-rings with a handle – Synthesis of substituted cycloparaphenylenes

• Anne-Florence Tran-Van and
• Hermann A. Wegner

Beilstein J. Nanotechnol. 2014, 5, 1320–1333, doi:10.3762/bjnano.5.145

• absorption spectrum can be explained by a combination of the spectra of pyrene and [16]CPP, as a result of the poor conjugation between paraphenylene and 2,7-pyrenylene. The emission maximum appears at 430 nm similar to [12]–[18]CPPs. However, the quantum yield is found to be much smaller with 0.21 in

• the extension of the π-system. Fluorescence emission occurs at 491 nm which is similar to the corresponding CPP however with a quantum yield lowered by a factor of two [15]. Another naphthalene CPP has been synthesized by Batson and Swager [55], who used a similar strategy as the Itami group. They

Surface processes during purification of InP quantum dots

• Natalia Mordvinova,
• Pavel Emelin,
• Alexander Vinokurov,
• Sergey Dorofeev,
• Artem Abakumov and
• Tatiana Kuznetsova

Beilstein J. Nanotechnol. 2014, 5, 1220–1225, doi:10.3762/bjnano.5.135

• hypothesis is confirmed by the IR spectrum of the sample precipitated for the second time, which contains a peak that corresponds to P–H vibrations. After 30 days the quantity of free myristic acid decreases (Figure 6) and the quantum yield (QY) of luminescence increases (reaches more than 1%) as the result

• the second purification ODE completely leaves the QDs surface and the QDs look as shown in Figure 7c. After 30 days MA− that stabilizes the QD is hydrolyzed because of traces of water in air (Figure 8). Because of the poor stabilization of the QDs surface the quantum yield of luminescence does not

• the precipitation with acetone ODE admixture could hardly be removed. However, electrophoresis has some limitations: After purification through electrophoresis no luminescence is observed. To increase the quantum yield of QDs purified in such a way a postsynthetic treatment, for example photoetching

Optimizing the synthesis of CdS/ZnS core/shell semiconductor nanocrystals for bioimaging applications

• Li-wei Liu,
• Si-yi Hu,
• Ying Pan,
• Jia-qi Zhang,
• Yue-shu Feng and
• Xi-he Zhang

Beilstein J. Nanotechnol. 2014, 5, 919–926, doi:10.3762/bjnano.5.105

• bandgap (Eg) of 2.42 eV. By tailoring its composition and size, or surface functionality, it is possible to enhance luminescence emission and quantum yield of these QDs. The use of a coating agent can make CdS more stable. ZnS QDs are less cytotoxic than CdTe and CdSe QDs of the same size and surface

• core/shell-structured QDs are desirable due to their strongly enhanced quantum yield (QY). We also tested the QY of three samples based on Equation 1: Here, Φ and ΦS are the QYs for the sample and the standard, I (sample) and IS (standard) are the integrated emission peak areas, A (sample) and AS

Enhancement of photocatalytic H₂ evolution of eosin Y-sensitized reduced graphene oxide through a simple photoreaction

• Weiying Zhang,
• Yuexiang Li,
• Shaoqin Peng and
• Xiang Cai

Beilstein J. Nanotechnol. 2014, 5, 801–811, doi:10.3762/bjnano.5.92

• investigated with eosin Y (EY) as a sensitizer of the RGO and Pt as a co-catalyst. When the irradiation time is increased from 0 to 24 h the activity rises, and then reaches a plateau. Under optimum conditions (pH 10.0, 5.0 × 10−4 mol L−1 EY, 10 μg mL−1 RGO), the maximal apparent quantum yield (AQY) of EY

• irradiation time. The two factors lead to the enhancement of the photocatalytic hydrogen evolution over EY-RGO/Pt with increasing irradiation time. The maximal apparent quantum yield of EY-RGO24/Pt for hydrogen evolution is up to 12.9% under visible light irradiation (λ ≥ 420 nm), and 23.4% under

• spectrum: 400–700 nm) was 363 μmol m−2 s−1. The apparent quantum yield (AQY) was calculated according to the following equation. The quantum yields under monochromatic light irradiation were also measured by using various monochromatic LED lamps (UVEC-4, Shenzhen LAMPLIC Science Co.Ltd, China) as light

Photoactivation of luminescence in CdS nanocrystals

• Valentyn Smyntyna,
• Bogdan Semenenko,
• Valentyna Skobeeva and
• Nikolay Malushin

Beilstein J. Nanotechnol. 2014, 5, 355–359, doi:10.3762/bjnano.5.40

• interfacial processes and the mechanism of the amplification of the quantum yield of quantum dots are still a subject of active discussion and require further clarification [5]. As noted in [2][3][4][5][10][11][12][13][14] the properties of luminescence are strongly dependent on the technology of the quantum

• nanocrystals, a formation of the oxide shell on the surface of the nanocrystals and a quenching of the luminescence. In these cases one can observe processes of passivation of surface states, which contributes to an increase in the quantum yield of the luminescence. In [5] a systematic investigation of the

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