Optical orientation of nematic liquid crystal droplets via photoisomerization of an azodendrimer dopant

• Sergey A. Shvetsov,
• Alexander V. Emelyanenko,
• Natalia I. Boiko,
• Alexander S. Zolot'ko,
• Yan-Song Zhang,
• Jui-Hsiang Liu and
• Alexei R. Khokhlov

Beilstein J. Nanotechnol. 2018, 9, 870–879, doi:10.3762/bjnano.9.81

• reduction of the trans isomer order parameter, Strans. The obtained data allow one to estimate the trans isomer order parameter and the ratio of isomers under varying LED irradiation. First, the cis isomer absorption coefficient should be determined. It is convenient to use the spectra after LED

• Xcis = 0.74 at λmax = 398 nm, while the absorption coefficient at λ = 365 nm was found to be αcis = 6 cm−1. For the G5-doped NLC, we have found Xcis = 0.93 at λmax = 365 nm, Xcis = 0.81 at λmax = 398 nm, and αcis = 10 cm−1 at λ = 365 nm. Then, we obtain the dependence of the trans isomer order

• , Strans, [47] as where is the average absorption coefficient of the trans isomers. If the unpolarized light beam falls normally on the planarly oriented NLC film, the absorption coefficient equals Without light irradiation, there are only trans isomers. Therefore the absorption spectrum of trans isomers

Mechanistic insights into plasmonic photocatalysts in utilizing visible light

• Kah Hon Leong,
• Azrina Abd Aziz,
• Lan Ching Sim,
• Pichiah Saravanan,
• Min Jang and
• Detlef Bahnemann

Beilstein J. Nanotechnol. 2018, 9, 628–648, doi:10.3762/bjnano.9.59

• . Direct optical absorption The direct detection of H2O2 in solution by measuring UV spectra is difficult due to the weak molar absorption coefficient of H2O2 (0.01 M−1 cm−1) at 360 nm, which gradually increases up to 13 M−1 cm−1 at the wavelength of 260 nm [115]. Meanwhile, the optical absorption in the

Facile synthesis of ZnFe₂O₄ photocatalysts for decolourization of organic dyes under solar irradiation

• Arjun Behera,
• Debasmita Kandi,
• Sanjit Manohar Majhi,
• Satyabadi Martha and
• Kulamani Parida

Beilstein J. Nanotechnol. 2018, 9, 436–446, doi:10.3762/bjnano.9.42

• temperature the absorption of the materials shifted towards higher wavelengths. The band-gap energy of ZFO-500 has been calculated with the help of Tauc plots using Equation 1 [30]: where α, h, ν, Eg, and A are absorption coefficient, Plancks constant, frequency of light, band-gap energy and a proportionality

One-step chemical vapor deposition synthesis and supercapacitor performance of nitrogen-doped porous carbon–carbon nanotube hybrids

• Egor V. Lobiak,
• Lyubov G. Bulusheva,
• Ekaterina O. Fedorovskaya,
• Yury V. Shubin,
• Pavel E. Plyusnin,
• Pierre Lonchambon,
• Boris V. Senkovskiy,
• Zinfer R. Ismagilov,
• Emmanuel Flahaut and
• Alexander V. Okotrub

Beilstein J. Nanotechnol. 2017, 8, 2669–2679, doi:10.3762/bjnano.8.267

• card 000-89-2868) (Figure 4). It is difficult to detect individual metallic phases such as Co, Ni, and Fe apparently due to the small amount present. Furthermore, these metals have a lower linear absorption coefficient in comparison with heavier Mo. Actually, the XRD analysis of the decomposition

Changes of the absorption cross section of Si nanocrystals with temperature and distance

• Michael Greben,
• Petro Khoroshyy,
• Sebastian Gutsch,
• Daniel Hiller,
• Margit Zacharias and
• Jan Valenta

Beilstein J. Nanotechnol. 2017, 8, 2315–2323, doi:10.3762/bjnano.8.231

• the optical absorption coefficient [9]. The NC concentration is necessary for many scientific studies and practical applications such as biolabeling [3]. Besides this, the ACS is related to the transition oscillator strength and therefore, is a very useful parameter for a variety of theoretical

• [9][10] to the absorption coefficient α normalized by the volume concentration of NCs, cV, (σ = α/cV). Finally, by substituting Equation 23 into the approximation presented by Kovalev et al. [29], the temperature dependence of the ACS at a fixed energy of absorbed photons, , can be estimated as: The

Optical techniques for cervical neoplasia detection

• Tatiana Novikova

Beilstein J. Nanotechnol. 2017, 8, 1844–1862, doi:10.3762/bjnano.8.186

• is usually modeled by the Monte Carlo algorithm. The fit of the measured spectral data with the optical model of tissue provides the effective values of diagnostically relevant model parameters, e.g., reduced scattering coefficient and absorption coefficient. In the optical model of tissue these

Laser processing of thin-film multilayer structures: comparison between a 3D thermal model and experimental results

• Babak B. Naghshine and
• Amirkianoosh Kiani

Beilstein J. Nanotechnol. 2017, 8, 1749–1759, doi:10.3762/bjnano.8.176

• the temperatures are below the boiling point. Plasma shielding and power loss A plasma absorption coefficient was introduced for the plasma shielding effect (Equation 8) [21]. αmax is the maximum absorption that corresponds to the highest possible pulse power. ψ is non-dimensionalized pulse power

Study of the correlation between sensing performance and surface morphology of inkjet-printed aqueous graphene-based chemiresistors for NO₂ detection

• F. Villani,
• C. Schiattarella,
• T. Polichetti,
• R. Di Capua,
• F. Loffredo,
• B. Alfano,
• M. L. Miglietta,
• E. Massera,
• L. Verdoliva and
• G. Di Francia

Beilstein J. Nanotechnol. 2017, 8, 1023–1031, doi:10.3762/bjnano.8.103

• account the filter mass. UV–vis (200–850 nm) transmittance spectra of a diluted set of this dispersion have been performed by means of a Shimadzu UV-1800 UV–vis spectrophotometer. In all cases, UV–vis absorbance spectra have been measured that appeared flat and featureless [5]. The absorption coefficient

Synthesis of graphene–transition metal oxide hybrid nanoparticles and their application in various fields

• Arpita Jana,
• Elke Scheer and
• Sebastian Polarz

Beilstein J. Nanotechnol. 2017, 8, 688–714, doi:10.3762/bjnano.8.74

Dispersion of single-wall carbon nanotubes with supramolecular Congo red – properties of the complexes and mechanism of the interaction

• Anna Jagusiak,
• Barbara Piekarska,
• Tomasz Pańczyk,
• Małgorzata Jemioła-Rzemińska,
• Elżbieta Bielańska,
• Barbara Stopa,
• Grzegorz Zemanek,
• Janina Rybarska,
• Irena Roterman and
• Leszek Konieczny

Beilstein J. Nanotechnol. 2017, 8, 636–648, doi:10.3762/bjnano.8.68

• total amount of CR added to the sample. UV–vis absorption spectra were recorded on a Cary 300Bio Varian spectrophotometer. Absorption coefficient for CR: ε489 = 50.46 M−1·cm−1. In order to avoid errors caused by clogging of the membrane (in case of samples containing higher amounts of CR) the filtering

Colorimetric gas detection by the varying thickness of a thin film of ultrasmall PTSA-coated TiO₂ nanoparticles on a Si substrate

• Urmas Joost,
• Andris Šutka,
• Meeri Visnapuu,
• Aile Tamm,
• Meeri Lembinen,
• Mikk Antsov,
• Kathriin Utt,
• Krisjanis Smits,
• Ergo Nõmmiste and
• Vambola Kisand

Beilstein J. Nanotechnol. 2017, 8, 229–236, doi:10.3762/bjnano.8.25

• properties (refractive index n, absorption coefficient k) of the films using the “Winelli II” software. Film thickness and optical constants were determined from the ellipsometric parameters tan ψ and cos Δ [11]. All the main parameters (d, n, and k) were obtained using a Levenberg–Marquardt non-linear

Sb₂S₃ grown by ultrasonic spray pyrolysis and its application in a hybrid solar cell

• Erki Kärber,
• Atanas Katerski,
• Ilona Oja Acik,
• Arvo Mere,
• Valdek Mikli and
• Malle Krunks

Beilstein J. Nanotechnol. 2016, 7, 1662–1673, doi:10.3762/bjnano.7.158

• coefficient α, we used 100 nm as a rough estimation of the optically effective thickness of the Sb2S3 layer based on the SEM image of Sb2S3 grown using three cycles (Figure 3). The resulting values of the absorption coefficient α of the Sb2S3 layers are presented in Figure 4. The α values remain above 5 × 104

• the number of deposition cycles used when grown using spray of 1:6 solutions onto a glass/ITO/TiO2 stack (Figure 5). The bandgap of the Sb2S3 was calculated using the spectra of the absorption coefficient of the glass/ITO/TiO2/Sb2S3 layer stacks (Figure 4B). The bandgaps obtained are in accordance

• layers of single-phase stoichiometric Sb2S3 crystals can be prepared by using the CSP technique. To sum up, based on the single-phase Sb2S3 composition of the layers as determined by Raman spectroscopy, and supported by the optical study, namely a bandgap of 1.6 eV, as well as an absorption coefficient

Manufacturing and investigation of physical properties of polyacrylonitrile nanofibre composites with SiO₂, TiO₂ and Bi₂O₃ nanoparticles

• Tomasz Tański,
• Wiktor Matysiak and
• Barbara Hajduk

Beilstein J. Nanotechnol. 2016, 7, 1141–1155, doi:10.3762/bjnano.7.106

• , and associated with it an increase in the dielectric constant. 3.2 The study of the width of the energy gap of the produced layers The dependence of the absorption coefficient of a studied material on the energy of the incident radiation on its surface is [40]: where α is the absorption coefficient, h

• using ellipsometry studies and provided the values of the extinction coefficient k, i.e., the imaginary part of the refractive index. Using the relationship between the absorption coefficient α and the extinction coefficient k: where λ is the length of the electromagnetic wave incident on the sample

• determines the width of the band gap. The second method allowing one to determine the relationship between the absorption coefficient α and the energy of the electromagnetic waves is using UV–vis spectral analysis of the obtained fibrous layers. In this case, the nanofibres were directly deposited on

Determination of Young’s modulus of Sb₂S₃ nanowires by in situ resonance and bending methods

• Liga Jasulaneca,
• Raimonds Meija,
• Alexander I. Livshits,
• Juris Prikulis,
• Subhajit Biswas,
• Justin D. Holmes and
• Donats Erts

Beilstein J. Nanotechnol. 2016, 7, 278–283, doi:10.3762/bjnano.7.25

• photosensitivity [3], its large absorption coefficient [4][5] and direct band gap in the visible and near infrared range (1.78–2.5 eV) [6][7][8]. Owing to these properties, Sb2S3 has also been considered as an attractive material for microwave frequency [9], optical recording [10] and photovoltaic [2][11

Influence of wide band gap oxide substrates on the photoelectrochemical properties and structural disorder of CdS nanoparticles grown by the successive ionic layer adsorption and reaction (SILAR) method

• Mikalai V. Malashchonak,
• Alexander V. Mazanik,
• Olga V. Korolik,
• Еugene А. Streltsov and
• Anatoly I. Kulak

Beilstein J. Nanotechnol. 2015, 6, 2252–2262, doi:10.3762/bjnano.6.231

• energy (EU) values given below should be considered with reasonable skepticism due to the fact that EU is derived from the photocurrent spectrum range with a small absorption coefficient where the light scattering extending an optical path length is able to significantly influence the spectral dependence

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

• . Thus, the larger trans→cis conversion in the complex must be due to the fact that its molar absorption coefficient at 365 nm is higher than that of the free axle. When the irradiation light is also absorbed by the ring component (e.g., at λ = 287 nm), the situation becomes even more interesting

Nonlinear optical properties of near-infrared region Ag₂S quantum dots pumped by nanosecond laser pulses

• Li-wei Liu,
• Si-yi Hu,
• Yin-ping Dou,
• Tian-hang Liu,
• Jing-quan Lin and
• Yue Wang

Beilstein J. Nanotechnol. 2015, 6, 1781–1787, doi:10.3762/bjnano.6.182

• use as NIR emitters [12][13][14][15][16][17][18][19]. Ag2S QDs have a band gap of 1.1 eV, the appropriate narrow band gap for NIR emission, and a relatively large absorption coefficient, which may enhance the emission intensity. Therefore, Ag2S QDs provide a powerful route for improving the optical

• -scans, which is because of the combination of nonlinear effects in the system [22]. When the laser interacts with the QDs, free-carrier absorption, nonlinear scattering, and saturable absorption will occur, which all contribute to nonlinear behavior. In semiconductor QDs the absorption coefficient and

• ]: Here, T0 is the linear transmission, T′ is the nonlinear transmission, I0 is the input pulse energy, and the absorption coefficient β was obtained through Equation 4: Here, T0 is the normalized peak height, P is the pulse peak power, ω0 is the beam waist radius, Leff is the effective length in medium

Superluminescence from an optically pumped molecular tunneling junction by injection of plasmon induced hot electrons

• Kai Braun,
• Xiao Wang,
• Andreas M. Kern,
• Hilmar Adler,
• Heiko Peisert,
• Thomas Chassé,
• Dai Zhang and
• Alfred J. Meixner

Beilstein J. Nanotechnol. 2015, 6, 1100–1106, doi:10.3762/bjnano.6.111

• the focus ΦL, the effective absorption coefficient, σ, taking into account the near-field effect and the lifetimes of the hot electrons, . From the incident radiation and the spectrally integrated emission intensity of the pure junction, σ is estimated to be on the order of 10−6. In our case, the hot

Nanostructuring of GeTiO amorphous films by pulsed laser irradiation

• Valentin S. Teodorescu,
• Cornel Ghica,
• Adrian V. Maraloiu,
• Mihai Vlaicu,
• Andrei Kuncser,
• Magdalena L. Ciurea,
• Ionel Stavarache,
• Ana M. Lepadatu,
• Nicu D. Scarisoreanu,
• Andreea Andrei,
• Valentin Ion and
• Maria Dinescu

Beilstein J. Nanotechnol. 2015, 6, 893–900, doi:10.3762/bjnano.6.92

• if the physical properties of the films are known. The most important are the absorption coefficient of the laser radiation in the films and the heat diffusivity. Some of these parameters can be considered to be similar to those in bulk material, but in many cases of amorphous or multi-component

• depths of the surface layer during the laser pulse action. For the calculation, the physical parameters were set to maximize the temperature. The absorption coefficient used is 106 cm−1 (similar to Ge [17]), and the heat diffusivity is similar to that of TiO2 (0.02 cm2/s). Even under these conditions

Experimental determination of the light-trapping-induced absorption enhancement factor in DSSC photoanodes

• Serena Gagliardi and
• Mauro Falconieri

Beilstein J. Nanotechnol. 2015, 6, 886–892, doi:10.3762/bjnano.6.91

• determines the light harvesting properties of the cell, if all other optical phenomena are neglected. However, the most commonly used dye, N719, has a low absorption coefficient for red or longer wavelengths [3]. In practice, the nanostructured, porous titania film scatters the light, so that light trapping

Structural, optical, opto-thermal and thermal properties of ZnS–PVA nanofluids synthesized through a radiolytic approach

• Alireza Kharazmi,
• Nastaran Faraji,
• Roslina Mat Hussin,
• Elias Saion,
• W. Mahmood Mat Yunus and
• Kasra Behzad

Beilstein J. Nanotechnol. 2015, 6, 529–536, doi:10.3762/bjnano.6.55

• concentration in agreement with the FTIR results. The optical band gap energy of the ZnS NPs was estimated through the Tauc equation as follows [6]: where α is the absorption coefficient, hν is the photon energy of the incident light, Eg is the band gap energy, B is a constant and n depends on the type of

• -axis, indicates the band gap energy of the ZnS NPs, as shown in Figure 6. The absorption coefficient (α) was calculated by α = 2.303 A/d where A is the absorbance and d is the thickness of the sample [27]. The band gap of ZnS NPs decreased from 3.74 to 3.68 eV with increasing dose from 10 to 50 kGy due

Electrical properties of single CdTe nanowires

• Elena Matei,
• Camelia Florica,
• Andreea Costas,
• María Eugenia Toimil-Molares and
• Ionut Enculescu

Beilstein J. Nanotechnol. 2015, 6, 444–450, doi:10.3762/bjnano.6.45

• solar cells and its high absorption coefficient makes it extremely efficient. Figure 3 gives the optical reflection spectra for arrays of CdTe nanowires prepared at different overvoltages. The band gap of the semiconductor was determined to be 1.49 eV by employing the Kubelka–Munk function. This value

Photodetectors based on carbon nanotubes deposited by using a spray technique on semi-insulating gallium arsenide

• Domenico Melisi,
• Maria Angela Nitti,
• Marco Valentini,
• Antonio Valentini,
• Teresa Ligonzo,
• Giuseppe De Pascali and
• Marianna Ambrico

Beilstein J. Nanotechnol. 2014, 5, 1999–2006, doi:10.3762/bjnano.5.208

• 900 and 1000 nm. Assuming the photocurrent directly proportional to the GaAs absorption coefficient and direct gap transitions, an absorption edge of 1.38 eV has been obtained for all the spectra. This value is slightly lower than the energy gap of GaAs at room temperature (1.42 eV) [18]. As mentioned

An insight into the mechanism of charge-transfer of hybrid polymer:ternary/quaternary chalcopyrite colloidal nanocrystals

• Parul Chawla,
• Son Singh and
• Shailesh Narain Sharma

Beilstein J. Nanotechnol. 2014, 5, 1235–1244, doi:10.3762/bjnano.5.137

• this class of materials with polymers such as high absorption coefficient (~105 cm−1), high reproducibility, high efficiencies and good stability [8][9][10] in comparison to the other inorganic–organic nanocomposites based devices. The superior characteristic properties of chalcopyrite based

• in Figure 3C(a–c), which shows the enhancement of the optical bandgap (as calculated from the Tauc’s plot involving the absorption coefficient, α and the photon energy hν) from CISe to CZTSe. The bandgap values of pristine CISe, CIGSe and CZTSe are ≈1.03 eV, 1.1 eV and 1.15 eV, respectively (Figure

Electron-beam induced deposition and autocatalytic decomposition of Co(CO)₃NO

• Florian Vollnhals,
• Martin Drost,
• Fan Tu,
• Esther Carrasco,
• Andreas Späth,
• Rainer H. Fink,
• Hans-Peter Steinrück and
• Hubertus Marbach

Beilstein J. Nanotechnol. 2014, 5, 1175–1185, doi:10.3762/bjnano.5.129

• linear absorption coefficient. The peak shape and the energy of the resonant Co L3 transition are similar for all deposits, which supports a common attenuation coefficient for this energy. The spectral intensities in Figure 4 also indicate that the layer thickness increases with growth time. As the

• not known, the linear absorption coefficient of the deposited material, µdeposit, is also unknown. As an approximation, we use the value of pure Co, µCo, instead and denote the derived thickness value as apparent cobalt thickness, dA, which is calculated by using Equation 1. Since the oxygen, nitrogen

• routine operation for the applied zone plate was 30 to 40 nm. The STXM data were analyzed using aXis2000 (http://unicorn.mcmaster.ca/aXis2000.html). The value for the absorption coefficient at the resonant transition was determined by fitting the spectrum of a PVD Co layer to a theoretical spectrum (“X