Observation of a hole-size-dependent energy shift of the surface-plasmon resonance in Ni antidot thin films

© 2015 AIP Publishing LLC. A combined experimental and theoretical study of the magneto-optic properties of a series of nickel antidot thin films is presented. The hole diameter varies from 869 down to 636 nm, while the lattice periodicity is fixed at 920 nm. This results in an overall increase of the polar Kerr rotation with decreasing hole diameter due to the increasing surface coverage with nickel. In addition, at photon energies of 2.7 and 3.3 eV, where surface-plasmon excitations are expected, we observe distinct features in the polar Kerr rotation not present in continuous nickel films. The spectral position of the peaks exhibits a red shift with decreasing hole size. This is explained within the context of an effective medium theory by a change in the effective dielectric function of the Ni thin films.H.F. gratefully acknowledges China Scholarship Council (CSC) for financial support and André Schirmeisen for the data of Ni film. A.G.-M. and B.C. acknowledge funding from Spanish Ministry of Economy and Competitiveness through grants “FUNCOAT” CONSOLIDER CSD2008-00023 and “MAPS” MAT2011-29194-C02-01. J.C.C. acknowledges financial support from the Spanish Ministry of Economy and Competitiveness (Contract No. FIS2011-28851-C02-01) and from the Comunidad de Madrid (Contract No. S2013/MIT-2740). E.M.A. and M.G. acknowledge financial support by the European Union under the project CosmoPHOS with the number “3100337”.Peer Reviewe

Observation of a hole-size-dependent energy shift of the surface-plasmon resonance in Ni antidot thin films

A combined experimental and theoretical study of the magneto-optic properties of a series of nickel antidot thin films is presented. The hole diameter varies from 869 down to 636 nm, while the lattice periodicity is fixed at 920 nm. This results in an overall increase of the polar Kerr rotation with decreasing hole diameter due to the increasing surface coverage with nickel. In addition, at photon energies of 2.7 and 3.3 eV, where surface-plasmon excitations are expected, we observe distinct features in the polar Kerr rotation not present in continuous nickel films. The spectral position of the peaks exhibits a red shift with decreasing hole size. This is explained within the context of an effective medium theory by a change in the effective dielectric function of the Ni thin filmsH.F. gratefully acknowledges China Scholarship Council (CSC) for financial support and André Schirmeisen for the data of Ni film. A.G.-M. and B.C. acknowledge funding from Spanish Ministry of Economy and Competitiveness through grants “FUNCOAT” CONSOLIDER CSD2008-00023 and “MAPS” MAT2011-29194-C02-01. J.C.C. acknowledges financial support from the Spanish Ministry of Economy and Competitiveness (Contract No. FIS2011-28851-C02-01) and from the Comunidad de Madrid (Contract No. S2013/MIT- 2740). E.M.A. and M.G. acknowledge financial support by the European Union under the project CosmoPHOS with the number “310337

Optimization of hierarchical structure and nanoscale enabled plasmonic refraction for window electrodes in photovoltaics

An ideal network window electrode for photovoltaic applications should provide an optimal surface coverage, a uniform current density into and/or from a substrate, and a minimum of the overall resistance for a given shading ratio. Here we show that metallic networks with quasi-fractal structure provides a near-perfect practical realization of such an ideal electrode. We find that a leaf venation network, which possesses key characteristics of the optimal structure, indeed outperforms other networks. We further show that elements of hierarchal topology, rather than details of the branching geometry, are of primary importance in optimizing the networks, and demonstrate this experimentally on five model artificial hierarchical networks of varied levels of complexity. In addition to these structural effects, networks containing nanowires are shown to acquire transparency exceeding the geometric constraint due to the plasmonic refraction

Exploring marine ecosystems with elementary school Portuguese children: inquiry-based project activities focused on ‘real-life’ contexts

The purpose of the study was to investigate how young students engage in an inquirybased project driven by real-life contexts. Elementary school children were engaged in a small inquiry project centred on marine biodiversity and species adaptations. All activities included the exploration of an out-of-school setting as a learning context. A total of 49 students and 2 teachers were involved in the activities. The research methods included observation, document analysis and content analysis of the answers to a questionnaire and an interview. The results revealed that most of the students acquired scientific knowledge related to biological diversity and adaptations to habitat. Moreover, students progressively demonstrate greater autonomy, argumentative ability and decision-making. One implication of the present study is that elementary science curriculum could be better managed with inquiry projectbased activities that explore different types of resources and out-of-school settings.info:eu-repo/semantics/publishedVersio

Preliminary investigations on two different procedures to calculate the efficiency and performance ratio of PV modules

Short- and long-term outdoor performances of the photovoltaic (PV) modules are extremely important in reaching their economic viabilities. Such information is very valuable for the investors, customers and researchers of PV technologies. Two different procedures are possible, and both are used by many researchers. However, to the best of our knowledge, there is no comparative investigation to evaluate these two procedures. One of the methods uses instantaneous I-V curves of PV modules taken in a specified instant of time, while the others simply use the integrated energy values of the input and the yield of PV modules. In fact, both have advantages and disadvantages. In the present work, we outlined the advantages and disadvantages of both methods and compared them using the data of two different cell-type modules which are installed at GuNAM's outdoor test facility. In the analysis, the data that we used are taken under the same outdoor test conditions and ambient weather conditions. The outcomes of these preliminary analyses can be summarized as follows: (1) The procedure that uses instantaneous I-V curves seems dependent on the specified time intervals and ambient weather conditions at that instant; (2) accordingly, we will propose how to determine an optimal time interval to reach better performance results; (3) using the integrated values, we achieved the variations in performances with different integration time periods; (4) preliminary comparisons of these two procedures resulted in key conclusions on performance and degradation calculations of PV modules

Is there a macroeconomic carbon rebound effect in EU ETS?

This study examines the macroeconomic carbon rebound effect for the European Union (EU) Emissions Trading System (ETS) by using data for the 2005–2019 period for 26 European countries. We estimate the panel data models which link emissions to allowances by controlling for economic growth, investment, employment, and energy intensity. The results from both the recent panel estimation approaches and Granger causality analysis indicate a macroeconomic carbon rebound effect of the EU ETS. The bidirectional Granger causality between emissions and allowances highlights a self-enforcing macroeconomic rebound. Energy intensity significantly impacts emissions directly and indirectly via the macroeconomic rebound effect. Our results show that positive economic spillovers of ETSs may hamper the efforts to meet climate targets. © 2023 The Author

Dynamic thermal modelling of PV performance and effect of heat capacity on the module temperature

One of the main weaknesses of Si-based Photovoltaic (PV) solar modules is the sensitivity of their efficiency to module (cell) temperature. Especially in locations with long hot seasons, the efficiency loss of PVs due to high temperatures should be considered carefully. Thermal modelling is a method to predict the performance of a PV module using essentially the 1st law of thermodynamics and available data. In this paper, a transient thermal model is described, which considers hourly meteorological data, including wind speed and direction, module parameters, and locational information. In transient analysis, the heat capacity value of PV panel is required, but it is not a parameter specified in the manufacturer's datasheet. Experiments on the heat capacity of PV modules are missing in the literature. The thermal model provides verified performance analysis for a poly-c-Si PV module installed in Ankara, Turkey, with a calculated heat capacity value. And a sensitivity analysis for the heat capacity of the transient thermal model is performed. It is found that the model results are almost invariant under changing module heat capacity values.Ministry of DevelopmentTurkiye Cumhuriyeti Kalkinma BakanligiThe authors would like to thank to GUNAM, The Center for Solar Energy Research and Applications, and assistance of Dr. R. Turan. The authors also acknowledge the support of the Ministry of Development during the construction process of GUNAM's outdoor testing facility.WOS:0006007896000232-s2.0-8509368220

Combining the satellite imagery with bright sunshine hours: A review

Present article is a review of recent researches on linking the satellite image data to surface measured bright sunshine hours. It first gives some basics on estimation procedures of the daily global solar irradiation on horizontal surface with the daily bright sunshine hours. Second, a satellite based model is presented briefly. Then, two recent combined models are reviewed and compared with the conventional models. The results on using one of the presented methods are discussed and recommended, for a couple of various cases which are classified by available data of the site of interest. It is concluded that the use of one of the combined model gives one of the best estimation performance for the daily global solar irradiation at the Earth's surface, whenever both of the data of bright sunshine and cloud index are available. However, satellite based model HELIOSAT also performs with high accuracy except for a number of days of one of the data sets. Hence, another conclusion is that, for the daily estimations, the use of HELIOSAT type satellite based models should be preferred, instead of using an Angstrom-Prescott type correlation of a location at a far point and/or having a different climate. Finally, a quadratic correlation which was tested for too many locations all over the world also performs quite accurately. Therefore, if only the bright sunshine hour data is available for a site, use of this quadratic correlation should be preferred. (C) 2013 AIP Publishing LLC

Physics of transparent conductors

Transparent conductors (TCs) are materials, which are characterized by high transmission of light and simultaneously very high electrical DC conductivity. These materials play a crucial role, and made possible numerous applications in the fields of electro-optics, plasmonics, biosensing, medicine, and “green energy”. Modern applications, for example in the field of touchscreen and flexible displays, require that TCs are also mechanically strong and flexible. TC can be broadly classified into two categories: uniform and non-uniform TC. The uniform TC can be viewed as conventional metals (or electron plasmas) with plasma frequency located in the infrared frequency range (e.g. transparent conducting oxides), or ultra-thin metals with large plasma frequency (e.g. graphen). The physics of the nonuniform TC is much more complex, and could involve transmission enhancement due to refraction (including plasmonic), and exotic effects of electron transport, including percolation and fractal effects. This review ties the TC performance to the underlying physical phenomena. We begin with the theoretical basis for studying the various phenomena encountered in TC. Next, we consider the uniform TC, and discuss first the conventional conducting oxides (such as indium tin oxide), reviewing advantages and limitations of these classic uniform electron plasmas. Next, we discuss the potential of single- and multiple-layer graphene as uniform TC. In the part of the paper dealing with non-uniform metallic films, we begin with the review of random metallic networks. The transparency of these networks could be enhanced beyond the classical shading limit by the plasmonic refractive effects. The electrical conduction strongly depends on the network type, and we review first networks made of individual metallic nanowires, where conductivity depends on the inter-wire contact, and the percolation effects. Next, we review the uniform metallic film networks, which are free of the percolation effects and contact problems. In applications that require high-quality electric contact of a TC to an active substrate (such as LED or solar cells), the network performance can be optimized by employing a quasi-fractal structure of the network. We also consider the periodic metallic networks, where active plasmonic refraction leads to the phenomenon of the extraordinary optical transmission. We review the relevant literature on this topic, and demonstrate networks, which take advantage of this strategy (the bio-inspired leaf venation (LV) network, hybrid networks, etc.). Finally, we review “smart” TCs, with an added functionality, such as light interference, metamaterial effects, built-in semiconductors, and their junctions