Island Films Research Articles

Bimodal functionality of highly conductive nanostructured silver film towards improved performance of photosystem I-based graphene photocathode

We present the novel design of photosystem I (PSI)-based biosolar cell, whereby conductive transparent electrode materials, such as ITO or FTO, are replaced with glass covered with silver island film. This nanostructured metallic layer combines high electric conductance with enhancing the absorption efficiency of the PSI biocatalyst via the plasmonic effect. We demonstrate strong enhancement of the photocurrent generated in the biohybrid electrode composed of oriented layers of PSI reaction centers due to plasmonic interactions of the PSI fluorophores and redox centres with the conductive silver island film.

Plasmon-enhanced sensitization of singlet oxygen on silver island films

The influence of the plasmonic effect of silver island films on the absorption, fluorescence and long-term luminescence of rose bengal in polyvinyl butyral films has been studied. Under the plasmon effect, the optical density of the dye increased by 3.3 times, the fluorescence intensity by 8.5 times, and the long-lived fluorescence and phosphorescence by 7.08 times and 10.21, respectively. It is shown that in the plasmon field of metal nanoparticles, both an increase in the excitation rate and an increase in the rates of radiative decay of excited singlet and triplet states occur. Phosphorescence of singlet oxygen with a lifetime of 86.46 μs was observed when excited in the absorption band of rose bengal. Based on the calculation of the quenching constants of rose bengal phosphorescence by molecular oxygen molecules, it is shown that the plasmonic effect enhances the energy transfer from dye triplets to oxygen molecules in collision complexes [ТPS…3  g –] as a result of heteroannihilation. Subsequently, the triplet pair decomposes to form a singlet oxygen molecule and a photosensitizer molecule in the ground state. The plasmonic effect of silver nanoparticles leads to an increase in the generation of singlet oxygen by 4.8 times.

Surface Modification of ZnO Nanotubes by Ag and Au Coatings of Variable Thickness: Systematic Analysis of the Factors Leading to UV Light Emission Enhancement.

Surface modification by plasmonic metals is one of the most promising ways to increase the band-to-band excitonic recombination in zinc oxide (ZnO) nanostructures. However, the metal-induced modulation of the UV light emission depends strongly on the production method, making it difficult to recognize the mechanism responsible for charge/energy transfer between the semiconductor and a metal. Therefore, in this study, the ZnO/Ag and Au hybrids were produced by the same, fully controlled experimental approach. ZnO nanotubes (NTs), fabricated by a template-assisted ALD synthesis, were coated by metals of variable mass thickness (1-6.5 nm thick) using the electron beam PVD technique. The deposited Ag and Au metals grew in the form of island films made of metallic nanoparticles (NPs). The size of the NPs and their size distribution decreased, while the spacing between the NPs increased as the mass of the deposited Ag and Au metals decreased. Systematic optical analysis allowed us to unravel a specific role of surface defects in ZnO NTs in the processes occurring at the ZnO/metal interface. The enhancement of the UV emission was observed only in the ZnO/Ag system. The phenomena were tentatively ascribed to the coupling between the defect-related (DL) excitonic recombination in ZnO and the localized surface plasmon resonance (LSPR) at the Ag NPs. However, the enhancement of UV light was observed only for a narrow range of Ag NP dimensions, indicating the great importance of the size and internanoparticle spacing in the plasmonic coupling. Moreover, the enhancement factors were much stronger in ZnO NTs characterized by robust DL-related emission before metal deposition. In contrast to Ag, Au coatings caused quenching of the UV emission from ZnO NTs, which was attributed to the uncoupling between the DL and LSP energies in this system and a possible formation of the ohmic contact between the Au metal and the ZnO.

Electric field-assisted dissolution of bimetal-dielectric multilayer systems

The electric field-assisted dissolution (EFAD) of Ag and Au metal island films (MIFs) in multilayer structures is investigated. The samples consist of Au and Ag MIFs separated by SiO2 layers deposited on soda-lime glass substrates. The samples were subjected to two types of process: a) thermal annealing at 200°C, and b) application of 500 V dc voltage at 200°C. Spectroscopic ellipsometry and secondary ion mass spectrometry were used to track sample changes. It is shown that thermal annealing induces ion exchange between Ag and Na ions from the glass, leading to partial dissolution of Ag MIFs and Ag being incorporated in the glass and Au MIFs. EFAD process leads to the partial or complete dissolution of Ag films depending on the process duration, while Au dissolution turns out to be more difficult. The optical properties are consistent with the compositional changes and additionally suggest MIF morphology modifications. Numerical simulations of ion drift and diffusion reveal the importance of ion exchange during thermal annealing to enable an efficient MIF dissolution. Overall, the study helps to understand the EFAD of different metals in complex systems and provides insights for the application of this technique in systems containing several metals.

Strain-Sensitive Properties of Polymer Nanocomposites Based on Island Films

Strain-Sensitive Properties of Polymer Nanocomposites Based on Island Films

Challenges in surface‐enhanced Raman scattering signal for ethephon detection: Theoretical and experimental approaches

AbstractEthephon, a widely used growth regulator in fruits and vegetables, requires careful monitoring because of its toxicity. However, as far as we know, only two works are found in the literature regarding surface‐enhanced Raman scattering (SERS) ethephon detection. Indeed, obtaining the SERS signal revealed to be challenging. Therefore, we have evaluated the SERS signal of ethephon using theoretical (as density functional theory and charge‐assisted fragment interaction) and experimental approaches, addressing this limited literature knowledge. Theoretical Raman spectra with Ag or Au atoms at reactive sites exhibited enhanced ethephon SERS signal via AgCl bonding, consistent with the experimental data. Multiple experimental procedures were employed to obtain the SERS signal, including pH variations, salt addition, excitation laser lines, time dependency, and different SERS substrates (Ag colloid and Ag island films). Salt addition (NaCl) improved SERS signal, correlating with Ag colloid aggregation. Analysis in Ag colloid showed the pH 7.0 as optimal for ethephon detection, using freshly prepared Ag colloid + ethephon dispersion with ethephon powder being directly dissolved into Ag colloid. Only the AgCl band intensity improved with time. Ag colloid (wet medium — 633 nm laser line) outperformed Ag island films (dry medium — 785 nm laser line).

The effect of size and shape-dependent optical properties on colored radiative cooling in metal island films

We study visible and infrared optical absorption of metal island films that are commonly used for applications such as color filters and sensors. Calculations were performed using the T-matrix method and compared to experimental transmittance measurements at visible spectrum on a real sample. While the radiation transfer solution through these films often assumes (i) no plasmon coupling, (ii) spherical particles, (iii) monodispersed size particles and/or (iv) bulk refractive index, we carefully study the influence of these assumptions on spectral transmittance. After a validation of the method, the resulting performance in terms of solar energy absorption, color lightness and hue are evaluated on a radiative cooling structure. Alternative designs that provide stronger coloration and thermal performance are proposed and discussed.

Optical Characterization of Al Island Films: A Round Robin Test

The determination of the effective optical constants of metal island films is an essential step towards the practical incorporation of this kind of films in optical coatings. In this work, the optical properties of aluminium island films deposited by electron beam evaporation on quartz substrates are investigated using different approaches employed by three research groups. The effective optical constants of the island films are inferred from optical measurements (spectrophotometry and spectroscopic ellipsometry) using: (i) a parameter-free dispersion model, (ii) a multiple oscillator model based on Gaussian line-shapes and (iii) the β distributed oscillator model. All the used approaches provide similar physical insights, i.e., an increase in the effective thickness of the metal island film, a red-shift and broadening of the plasmon resonance and an enhancement of the infrared absorption as the amount of deposited material increases. However, the optimal values of the effective optical constants and thickness significantly depend on the employed model and the experimental data used for data fitting.

Morphological structure of the Pb island films melted on the Ta layer surface

An effective way to create self-organizing arrays of metal particles is to melt thin layers of substance on a poorly wetted surface. Such arrays may improve the technological properties of functional structures, and are themselves functional elements of modern devices and systems. During the melting of a solid layer on a poorly wetted substrate, an array of spherical particles is formed, which are evenly distributed over the surface of the substrate. The distribution of particles by size is determined by the thickness of the fusible layer and conditions of the deposition. The location of islands, formed after the melting of vapour-crystal deposited solid films, is determined primarily by the initial stages of de-wetting, when the thin continuous film starts to decay while remaining in solid state. This work studied self-organizing processes during the melting of Pb films deposited on a Ta substrate. The films were deposited on glass plates in a high vacuum and then after deposition were heated to a temperature slightly above the Pb melting point. After the heat treatment the samples were removed from the vacuum chamber and examined using SEM microscopy and EDS analysis. It was discovered that arrays of spherical particles are formed during the melting of micron-thick Pb films. The histograms of the size distribution of such particles are quite wide and can be represented as bimodal with partially overlapping maxima. This can be explained by active coalescence processes in thicker samples. This study demonstrated that small temperature gradients can cause noticeable kinetic effects that allow separate particles to move macroscopic distances and capture the surrounding substance. The study also estimated the energy associated with the optimization of the morphological structure of vacuum condensate and which is a physical factor of de-wetting.

The Main Character Development in The King of Staten Island Film

The research aimed to analyze the main character development in The King of Staten Island film by using Roberts and Zweig character change theory and Sigmund Freud's structure of personality theory. The researcher used The King of Staten Island film which was released in 2020 by Universal Pictures in association with Perfect World Pictures, and the film script as the source of data. This research used Roberts and Zweig’s character change theory, Sigmund Freud’s structure of personality theories, and Petrie and Boggs film characterization theory to analyze Scott Carlin's character. This research used qualitative method and content analysis approach also Mikos film analysis theory. The researcher confirmed Scott's structure of personality changed before Scott's character developed. Those three elements (id, ego, and superego) supported the character development of Scott Carlin. The result showed the id as the most frequently appeared structure with five data, followed by ego with three data, and lastly followed by superego with three data. It confirmed the id as the part which hinders Scott's development and the ego as the part which influenced Scott's development with the help of certain events in the story as the trigger. The researcher concluded Scott's character development became more courageous, composed, emotionally stable, mature, truthful about his feeling, could heed to other people's advice, control his emotion and anger, overcome his trauma, his hatred towards fireman is gone and admire this profession. On the other hand, the implication was that Scott's relationship with his family was restored, people's view towards Scott changed, and forgiveness of his past mistakes. Key words: Character development, (id, ego, and superego), structure of personality

In English

Zinc oxide nanostructures (NS) were grown on thin discontinuous films of noble metals of silver and gold in order to study their structure, optical properties as well as photocatalytic and antiviral activity. The paper presents the results of X-ray diffraction study, scanning electron microscopy study, photoluminescence and Raman measurements. X-ray diffraction experiments demonstrate similar patterns for all grown ZnO nanostructures. The SEM images of ZnO NS grown on Ag/Si and Au/Si wafers demonstrate more dense surface microstructure compared to ZnO NS grown on bare Si wafers. The most intensive ultraviolet and deep level emissions are observed for ZnO NS grown on Ag/Si wafers. Increase in thicknesses of Ag island film from 5 nm to 10 nm gives significant increase in intensity of ultraviolet and deep level emissions. Photocatalysis of grown ZnO nanostructures was studied by methyl orange dye degradation. Superior photocatalytic results are demonstrated by ZnO nanostructures grown on Ag/Si wafers, for which constants of dye degradation were twice higher than for ZnO nanostructures grown on Si and Au/Si substrates. The photocatalytic results correlates with photoluminescence spectra: more intensive photoluminescence in ultraviolet and visible ranges of optical spectrum leads to better photocatalytic performance. The cytotoxic effect of ZnO nanostructures was studied without photoactivation by the help of cell cultures MDCK and Hep-2 while the virucidal effect of ZnO nanostructures was studied by the help of Influenza A virus (H1N1) (strain FM / 1/47) and human adenovirus serotype 2 (HAdV2). ZnO nanostructures in a 1:10 dilution were not toxic to Hep-2 and MDCK cells. Most of the tested ZnO nanostructures exhibited no virucidal activity against human adenovirus serotype 2 (HAdV2) and influenza A virus (H1N1) (strain FM / 1/47) in the absence of photoexcitation.

From Prison to Censorship: Devil’s Island Films (1926–1940)

This article aims to explore the particularities of American movies about Devil’s Island during the 1930’s but also to analyse how this specific interworld war context had a deep impact in the depiction of this penal colony. We refer to the methodological tools of cultural history to look at the United States and France internally and externally, using the movies as axes of interpretation regarding penal colonies, penal systems and old empires, but also to understand how a social imagery of Devil’s Island was slowly created through photos, documentaries, articles, features and memoirs.

The Effect of Local Doping of the Polymer–Polymer Interface Using Cu2O Particles

Electrically conductive polymer materials are increasingly being used as electronic materials, for example, in thin-film transistors. However, the low mobility of charge carriers limits their use. One of the ways to increase the mobility of charge carriers can be the use of interface conductivity along the regions separating the two polymer films. It is important that it could be realized with non-conjugated polymers. There is no direct experimental evidence that the transport of charge carriers occurs along such an interface. It is impossible to deny the possibility of transport on the surfaces of polymer films. The purpose of this work is to study the current flow path in a multilayer sample by marking the polymer–polymer interface with a doping nanolayer of a Cu2O island film. Spectral methods in the field of electronic absorption of copper oxide were used to control the island film. The electronic parameters of the polymer–polymer interface were studied using injection methods and volt-ampere characteristics. Atomic force microscopy was used to control the thickness and uniformity of the samples. It was found that the doping of the polymer–polymer interface using Cu2O particles strongly affects the transport of charge carriers; in particular, the conductivity of the structure increases. It is established that this is due to an increase in the mobility of the charge carriers and a decrease in the height of the potential barrier at the 3D metal–2D interface area. Thus, it is established that the transport of charge carriers occurs along the polymer–polymer interface at the structure parameters specified in this work.

Bismuth Oxide-based Matrix Nanosystems for X-ray Contrast Diagnostics and Protection from Ionizing Radiation

The features of the bismuth oxide deposition by the ion layering method on matrices of anodic alumina and anodic titania have been studied. The formed nanostructured systems have been studied by means of electron micros copy, X-ray microanalysis, and X-ray spectroscopy. Two-layer nanocomposites consist of porous matrix or TiO2 island film with vertically oriented Bi2O3 plates placed on the surface. The photoluminescence spectrum of Al2O3/Bi2O3 oxide structure contains two photoluminescence channels with peaks at 460 and 560 nm upon excitation at 345 nm. Analysis of the EDX spectra showed that the atomic ratio of Bi, Ti and O was 31.46 % Bi : 3.78 % Ti : 51.05 % O. The possibility of using complex nanocomposite as contrast agents in X-ray diagnostics and for protection against ionizing radiation is shown.

Anodization parameters influence on anodic aluminum oxide formed above the silver island film

Optical properties of hybrid plasmonic thin film structure in the form of anodic alumina porous matrix above silver island film on the quartz substrate have been investigated. Silver nanoparticle film in the bottom of the structure has been obtained by physical vapor deposition in a vacuum chamber. The silver island film with the island of average diameter of 100 nm has been formed after annealing in the air atmosphere. Above the silver nanoparticle film an aluminum film has been deposited by the E-beam evaporation. As a result of one-step straight anodization, a nanoporous alumina thin film has been formed. The obtained structures were investigated, using spectroscopy and electron microscopy methods. The structure reflectance and optical density spectra have been obtained and analyzed for different anodization times and currents. To compare the results, the reflectance and optical density spectra have been obtained for silver nanoparticles and anodic alumina. When anodization times are increased, structure reflection coefficient spectra become more like the same characteristic for anodic aluminum oxide, which can be explained by film oxidation. At the same time a red shift of reflectance spectrums is observed in the structures with bigger maximum anodization currents. This effect has been observed in other works and can be explained by the increasing distance between the pores. A numerical modeling of optical properties with the help of Mie calculator for the structure with the nanoparticle size of 100 nm has shown that the results of the modeling can be compared to the experimentally obtained optical density spectra. The modeling was performed using spherical approximation. To obtain more precise results for alumina film thickness and nanoparticle optical properties, a silver nanoparticle form factor has to be considered. The results of this work can be used in sensors, optical coatings and photon sources fabrication methods. These can be used in screens, optical schemes and many other plasmonic devices.

Enhancement of infrared absorption through a patterned thin film of magnetic field and spin-coating directed self-assembly of gold nanoparticle stabilised ferrofluid emulsion.

Molecular vibration signals were amplified by the gold strip gratings as a result of grating resonances and nearby electric field hotspots. Colloidal gold island films exhibit similar enhancement; however, the uneven geometrical characteristics of these films restrict the tunability of the vibrational enhancement. Infrared absorption is enhanced by regular metallic patterns such as arrays of strips fabricated using a top-down approach such as nanolithography, although this technology is expensive and difficult. The significant infrared absorption may serve as tuneable antenna sensitization to improve the sensor performance. In this article, we present a simple one-step process for fabricating optically sensitive ordered arrays of a gold nanoparticle ferrofluid emulsion in polyvinyl alcohol (PVA) using a magnetic field-directed and spin-coating self-assembly (MDSCSA) process. Techniques such as UV-visible absorption, scanning electron microscopy, and grazing-angle infrared spectroscopy were used to evaluate various parameters associated with the nanostructures. Unlike the gold strips, the chain-like features in the iron oxide nanoparticle arrays were discontinuous. The fabricated chain-like ordered arrays have been shown to increase the local field to enhance the infrared absorption corresponding to the symmetric vibration of the -CH2 (2918 cm-1) group present in PVA by ∼667% at a 45° grazing angle, as the chain thickness (CT) increased by 178%. This scalable and simple method can potentially generate low-cost patterns for antenna sensitisation.

Plasmon effect on triplet-singlet energy transfer in the dye-doped Langmuir-Blodgett films

The effect of silver plasmonic nanoparticles on triplet-singlet energy transfer in the donor-acceptor pair of organic dyes was studied. Layered dye films were prepared on the surface of glass and island silver films using the Langmuir-Blodgett method. Amphiphilic analogs of Rose bengal and polymethine dye were used as donor and acceptor of energy. A polymer monolayer was deposited between monolayers of donor and acceptor molecules to exclude the competing triplet-triplet energy transfer. The spectra of delayed fluorescence and phosphorescence of donor-acceptor films and the delayed luminescence lifetime of donor in these films have been measured. It is shown that a threefold increase in the fluorescence intensity and a twofold increase in the donor phosphorescence intensity are observed on silver island films. The successful triplet-singlet energy transfer is evidenced by both the quenching of donor centers and appearance of sensitized delayed fluorescence of the acceptor with the duration close to the donor triplet lifetime. In the presence of silver nanoparticles, in addition to enhancement in the intensity of the donor emission, an increase in the efficiency of tripletsinglet energy transfer was observed. The obtained results can be used in various optical devices.

Iron island films on sapphire grown by pulsed laser deposition with in situ electrical resistance monitoring

Iron island films were grown on sapphire by pulsed laser deposition with in situ electrical resistance control, which made it possible to precisely determine the percolation transition. Four growth stages can be distinguished: initial nucleation, independent island growth, ripening with channel formation, and island coalescence into a labyrinth structure. The morphology of the iron island films corresponded to these stages, depending on the time and deposition rate at a given temperature. At growth temperatures of T ≥ 350 °C, the percolation thickness exponentially depended on the temperature. The electrical response time τ of the system to a single pulse was<1 s, and the temperature dependence of 1/τ was linear in Arrhenius coordinates with a slope corresponding to an activation energy of 0.41 eV. The dependence of the film thickness and island diameter on the pulse frequency before the onset of the percolation transition reached a maximum, which can be explained by two competing factors: diffusion stimulation owing to the high kinetic energy of the incident particles and an increase in the number of initial nuclei in the substrate regions without islands.

High Tunable BaTixZr1-xO3 Films on Dielectric Substrate for Microwave Applications.

In this study, the structural and microwave properties of BaTiZrO3 films deposited on alumina substrate were investigated. The films were deposited by RF magnetron sputtering in Ar/O2 ambient atmosphere. The research of the island films at the initial stages of the growth showed that the pyramidal type of growth prevails. It was demonstrated that as-deposited film is a BaZrTiO3 solid solution with a deficiency of titanium compared to the target. The air annealing at temperatures of 1100–1200 °C leads to the formation of a well-formed crystalline solid solution of BaZr0.3Ti0.7O3 with a predominant orientation (h00). The investigation of microwave parameters of the films fabricated at different conditions showed that the best performance with the tunability of 4.6 (78%), and the Q-factor of 18 to 40 at 2 GHz was achieved at annealing temperature of 1150 °C.

Plasmon effect on simultaneous singlet-singlet and triplet-singlet energy transfer

The influence of plasmonic effect of Ag nanoparticles (NPs) on singlet-singlet (S–S) and triplet-singlet (T–S) energy transfer in the same donor–acceptor pair of organic molecules was studied. It was established that a 7-fold increase in the fluorescence and phosphorescence intensity of the energy donor (Rose bengal) and a 4-fold increase in the fluorescence intensity of the acceptor (polymethine dye) are observed on silver island films. The changes are associated with an increase in the emission rate of dye molecules, as evidenced by a decrease in the lifetime of their luminescence in the presence of Ag NPs. An increase in the efficiency of both types of energy transfer was recorded in the plasmon field of Ag NPs. The plasmon effect has almost the same influence on both S–S and T–S energy transfer. Estimation of the energy transfer rates using of the model of electric dipole interaction showed a good correlation between the experimental and calculated data for the S–S energy transfer.