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The high resolution Rydberg absorption spectrum of 2-butyne C4H6 recorded previously at the SOLEIL synchrotron facility has been interpreted using multichannel quantum defect theory (MQDT). The calculations are based on the continuum scattering calculations of Xu et al., J. Chem. Phys. 136, 154303 (2012) and of Jacovella et al., J. Phys. Chem. A 119, 12339 (2015) pertaining to the dipole-allowed excited state symmetries in absorption from the ground state. In contrast to the traditional approach of calculating low-lying electronic states first and then attempting to extend the calculations to ever higher energy, here the analysis proceeds through the extension of these detailed calculations of the electronic continuum scattering down into the discrete region of the spectrum. The continuum reaction matrices and dipole transition moments are adapted to the discrete Rydberg region via the use of an energy-modified formulation of MQDT theory and associated energy dependences of the quantum defects. The analysis reproduces more than 40 Rydberg states from n ≈ 10 down to the 3d and 4s levels with an rms error of better than 20 cm−1. These belong to five Rydberg series with three different molecular symmetries. While the approach predicts many additional series, most of these are calculated and observed to carry only little oscillator strength. The analysis shows that the Rydberg spectrum is dominated by the excitation of an e″ symmetry electron of fδ and gπ type, in line with what previous studies of the above-threshold shape resonance of 2-butyne have shown. The present study is intended to serve as an example showing how first principles continuum calculations may be useful for the interpretation of highly bound discrete states in a range that poses problems for the standard ab initio techniques. The quantitative treatment of the dipole absorption cross sections is deferred to a future paper. [ABSTRACT FROM AUTHOR]

Photometric ozone measurements rely upon an accurate value of the ozone absorption cross section at 253.65 nm. This has recently been reevaluated by Viallon et al. (2015) as 1.8% smaller than the accepted value (Hearn, 1961) used for the preceding fifty years. Thus, ozone measurements that applied the older cross section systematically underestimate the amount of ozone in air. We correct the reported historical surface data from North America and Europe and find that this modest change in cross section has a significant impact on the number of locations that are out of compliance with air quality regulations if the air quality standards remain the same. We find 18, 23, and 20% increases in the number of sites that are out of compliance with current US, Canadian, and European ozone air quality health standards for the year 2012. Should the new cross section value be applied, it would impact attainment of air quality standards and compliance with relevant clean air acts, unless the air quality target values themselves were also changed proportionately. We draw attention to how a small change in gas metrology has a global impact on attainment and compliance with legal air quality standards. We suggest that further laboratory work to evaluate the new cross section is needed and suggest three possible technical and policy responses should the new cross section be adopted. [ABSTRACT FROM AUTHOR]

Comparisons between total ozone column (TOC) measurements from ground-based Dobson and Brewer spectrophotometers and from various satellite instruments generally reveal seasonally varying differences of a few percent. A large part of these differences has been attributed to the operationally used Bass and Paur ozone cross sections and the lack of accounting for varying stratospheric temperatures in the standard total ozone retrieval for Dobson. This paper demonstrates how the use of new ozone absorption cross sections from the University of Bremen (Weber et al., 2016), as recommended by the Absorption Cross Sections of Ozone (ACSO) committee; the application of appropriate slit functions, especially for the Dobson instrument (Bernhard et al., 2005); and the use of climatological values for the effective ozone layer temperature (Teff), e.g., from TEMIS (Tropospheric Emission Monitoring Internet Service), essentially eliminate these seasonally varying differences between Brewer and Dobson total ozone data (to generally less than ±0.5 %). For Hohenpeissenberg, the previous seasonal difference (close to 0 % in summer and up to 2.5 % in winter) is reduced to less than ±0.5 % year-round. Implementing this approach to the existing global network of Dobson spectrometers will reduce the overall uncertainty in their total ozone data from 3 % to 4 % previously to under 2 % at most locations. [ABSTRACT FROM AUTHOR]

Based on the hypothesis that multi-corner and multi-cell structures can effectively improve energy absorption behavior, this paper designed a multi-cell circumferentially corrugated tube (MCCT) for energy absorption. The MCCT was designed as a variable thickness form to study the influence of the materials distribution on the cross section on energy absorption. The energy absorption performance of the MCCT was investigated under impact condition with finite element simulation validated by a drop hammer test. Support vector machine, a machine learning technique, was used to predict the energy absorption performance and was further used for optimization of the MCCT. The results show that under the same mass, the MCCT with variable decreasing wall thickness (corners thicker than other regions) shows 4.81%, 30.67% and 37.70% improvement, respectively, in PCF, SEA and CFE, compared to the MCCT with variable increasing wall thickness (corners thinner than other regions). Moreover, the optimization results show that most samples in Pareto front lie in the region of tc > tm. These results all indicate that the MCCT with variable decreasing wall thickness performs better than with increasing wall thickness with regards energy absorption. In conclusion, arranging more materials in the corner element area can effectively improve the energy absorption characteristics of the thin-walled tube. This paper highlights the importance of designing thin-walled tubes as multi-corner and variable thickness configurations for energy absorption. [ABSTRACT FROM AUTHOR]

Optical model or coupled-channels calculation serves as an entrance to sophisticated calculation of nuclear data. It gives the optical quantities such as total, shape elastic scattering, absorption cross sections, direct inelastic scattering cross sections, angular distributions of elastic and inelastic scattering, and transmission coefficients for subsequent statistical model calculations. Traditionally, coupling of the elastic scattering channel to excited states of the target nucleus was ignored or treated with a simplified model such as rigid rotor or harmonic oscillator. It was a great contribution of Dr. Efrem Sh. Soukhovitsukii who has developed an excellent computation scheme which takes account of the low-lying collective nuclear structure in terms of the soft-rotator + vibrational model, and integrated it into the coupled-channels calculation. This methodology was realized as 2 computer codes, SHEMMAN and OPTMAN. In Japan, we had a fortuitous experience with him to employ this methodology in nuclear data evaluation, which started as a nuclear physics work to analyze neutron-scattering cross section of 12 C which were published as a series of 3 papers in Nuclear Physics A journal. After recognizing the usefulness of this methodology, it was applied to evaluation of nuclear data gradually and extensively, which resulted in obtaining awards of Atomic Energy Society of Japan (AESJ) by one of the authors (SK). This paper describes our collaborative works and recent findings on light-nuclei based on what he had developed. [ABSTRACT FROM AUTHOR]

This paper aims to investigate the different properties of cobalt-doped and undoped tin oxide thin films. The tin oxide thin films were doped with different atomic percentages of cobalt, ranging from 0% (undoped) to 2% and 4%, using a cost-effective and easily accessible technique known as spray pyrolysis with a moving nozzle at 490 °C. The phase identification of the different thin layers was carried out using X-ray diffraction, which indicated that the compound is homogeneous has a polycrystalline structure and is, with preferential orientation growth at the (211) level. The optical properties of the synthesized thin films were investigated using UV-visible spectroscopy in the range from 300 to 900 nm, which allowed the estimation of both linear and nonlinear optical properties. The results of the investigations into the linear optical properties indicated that the samples have a direct band gap energy between 3.75 to 3.81 eV, permittivity between 2.67 to 3.266, photoelectrons between 0.2 to 3.35 = 1025, and refractive index between 1.778 to 1.875. The results also indicated that the absorption cross section changes with photon energy and the number of photoelectrons, where it has an approximately constant value at low energies. Moreover, the nonlinear optical properties were determined using the Sheik-Bahae model, which revealed that the samples have the same maximum two-photon absorption (TPA) process coefficient of 3.63 cm/W and the same maximum nonlinear refractive index (NRI) value of 6.91 × 10−8 cm2/W. [ABSTRACT FROM AUTHOR]

The development of fluorescent probe for hydrazine (N2H4) detection has attracted much attention due to the important role of N2H4 plays in the fields of medicine, agriculture, biology and environments. In this paper, the optical properties and water solubility of two novel two-photon fluorescent molecular probes (Probe1 and Probe2) before and after the reaction with N2H4 are studied by using the density function theory. The results show that electronic distribution and transition dipole moment of the probes are obviously changed after the reaction with N2H4, thus the optical properties of the molecules are influenced and the detection of N2H4 are realized. In addition, photoinduced electron transfer processes for Probe1 and Probe2 in the presence of N2H4 are theoretically characterized, which explains the experimental observations from the microscopic mechanism. Special attention has been paid on the analysis of the two-photon absorption for the probes with the absence and presence of N2H4 by the response theory method. Both probes with good water solubility show large variation on the two-photon absorption cross section when reacts with N2H4. In particular, the two-photon absorption response of Probe2 is more obvious, so it possesses preferable two-photon fluorescence microscopic imaging ability. More importantly, the receptor effect on the sensing performances of the probes are demonstrated, providing a theoretical reference for the design and synthesis on more efficient two-photon fluorescence N2H4 probes. Our study provides necessary information on the response mechanism of the studied chemosensors and helps to establish the relationship between the structure and optical properties of two-photon fluorescence N2H4 probes. [ABSTRACT FROM AUTHOR]

This paper investigates a hybrid coupled plasmonic gas sensor with stacked gold-SiO2 layers for air-quality monitoring. The gas absorption characteristics of hybrid-stacked layers sensors are studied and compared with single-layer sensors. Gases with different refractive indexes changing from 1 to 1.4 are studied. The total absorption radar cross section (ACS) has increased from 1.681 × 105 nm2 for single-layer sensors to 5.021 × 105 nm2 for hybrid stacked layers sensors. A graphene monolayer is used to enhance the total gas absorption. It acts as an insulator to the dipole sensor. The lumped-element equivalent circuit is developed using a particle swarm optimization technique (PSO). The sensitivity is 788 nm/RIU for the single-layer sensor and 910 nm/RIU for the hybrid-stacked layers sensor with a graphene monolayer placed as a cover for the plasmonic dipole. A polarization-insensitive sensor concerning the direction of the electric field (single layer/hybrid-stacked layers) is constructed from 45° quad-rotated dipole arms of sensors. The total ACS is enhanced to 2.31 × 105 nm2 for the polarization-insensitive single-layer sensor and 6.76 × 105 nm2 for the polarization-insensitive hybrid-stacked layers sensor. Planar arrays of 3 × 3, 4 × 4, and 5 × 5 elements of the last sensor are investigated for absorption and sensitivity enhancement. Ethanol, acetone, nitrogen dioxide, and toluene gases are tested with a total ACS peak value of 8.7 × 106 nm2. The sensitivity is 895.5 nm/RIU for 4 × 4 array elements. [ABSTRACT FROM AUTHOR]

Nd:GdVO4 has the advantages of a small thermal expansion coefficient, a large absorption bandwidth, and a large absorption and emission cross section, making it a good gain material for LED-pumping without active temperature control. In this paper, the LED-pumped Nd:GdVO4 laser was first generated in the quasi-continuous-wave and the passively Q-switched regime. With the incident pump energy of 8.0 mJ, the Nd:GdVO4 laser demonstrated energy of 195 μJ at 1063 nm in the quasi-continuous-wave regime, the slope efficiency was 4.7%, and the optical conversion efficiency was 2.4%. In the passively Q-switched regime, Cr:YAG was used as a saturable absorber and the energy obtained was 6.53 μJ with a pulse duration of 806.8 ns. These experimental results indicated the application prospect of LED-pumped lasers. [ABSTRACT FROM AUTHOR]

This paper presents the numerical simulation and fabrication of a metasurface composed of silver nanorings with a split-ring gap. These nanostructures can exhibit optically-induced magnetic responses with unique possibilities to control absorption at optical frequencies. The absorption coefficient of the silver nanoring was optimized by performing a parametric study with Finite Difference Time Domain (FDTD) simulations. The absorption and scattering cross sections of the nanostructures are numerically calculated to assess the impact of the inner and outer radii, the thickness and the split-ring gap of one nanoring, as well as the periodicity factor for a group of four nanorings. This showed full control on resonance peaks and absorption enhancement in the near infrared spectral range. The experimental fabrication of this metasurface made of an array of silver nanorings is achieved by e-beam lithography and metallization. Optical characterizations are then carried out and compared to the numerical simulations. In contrast to usual microwave split-ring resonator metasurfaces reported in literature, the present study shows both the realization by a top-down process and modelling performed in the infrared frequency range. [ABSTRACT FROM AUTHOR]

This work represents a first attempt at proposing a refined LII model suitable for simulating signals collected with excitation wavelengths (EWs) of 266, 355, 532 and 1064 nm. In this context, we implemented a comprehensive version of laser-irradiated soot heat and mass balance equations integrating terms representing the saturation of linear, single- and multi-photon absorption processes, cooling by sublimation, conduction, radiation and thermionic emission, as well as mechanisms depicting soot oxidation and annealing, non-thermal photodesorption of carbon clusters and corrective factors accounting for the shielding effect and multiple scattering (MS) within aggregates. This simulation tool was fully parameterized, by coupling design of experiments with a genetic algorithm-based solver, against data collected at different heights above the burner (HAB) in a diesel spray flame. This allowed to assess values of different model parameters involved in absorption and sublimation terms, which, to date, have never been reported in LII modeling studies for UV EWs (e.g., multi-photon absorption cross sections for C2 photodesorption and saturation coefficients for linear- and multi-photon absorption). The simulation work proposed herein then enabled to infer information regarding the evolution of the absorption function of soot ( E m , λ ). E m , 266 , E (m , 355) and E (m , 532) ranging from 0.25 to 0.51, 0.20 to 0.38 and 0.18 to 0.30, respectively, were notably estimated as a function of the HAB. Alternatively, values ranging from 0.31 to 0.53, 0.26 to 0.44 and 0.22 to 0.38 were assessed while neglecting the effect of MS and provided constant E (m , 266) / E (m , 1064) , E (m , 355) / E (m , 1064) and E (m , 532) / E (m , 1064) ratios of 1.4, 1.2 and 1.0, regardless of the HAB. In addition, the obtained results showed that the wavelength dependence of the soot absorption function was quite negligible for EWs higher than 532 nm, irrespective of whether the effect of MS was considered or neglected. On the other hand, aggregate properties were proven to substantially influence the E (m , λ) / E (m , 1064) ratios for decreasing λ and increasing HAB, thus illustrating the significant effect of aggregation on the optical properties of soot. Finally, the results issued from the different analyses we conducted on the diesel flame investigated in this paper led to the conclusion that values of E m , λ , falling within the 0.38 ± 0.15 and 0.29 ± 0.11 range at 266 and 355 nm, versus 0.25 ± 0.09 at 532 and 1064 nm could be considered as suitable for simulating LII signals of progressively aging aggregated particles. [ABSTRACT FROM AUTHOR]

Due to the plasmon hybridization between nanowire and outer nanotube, the geometrical parameters of nanotube take great effect on absorption cross section and local electric field enhancement. In this paper, we study the effects of the inner nanowire radius, shell thickness, middle dielectric functions and surrounding medium functions on absorption cross section and local electric field enhancement of bimetallic three-layered nanotubes, gold-dielectric-silver (GDS) nanotube and silver-dielectric-gold (SDG) nanotube in detail based on quasi-static theory. The results show that the thickness of outer nanotube plays a more role to tune local surface plasmon resonance (LSPR) than that of inner nanowire, whereas a better LSPR could be obtained with a higher surrounding dielectric function. In addition, the local electric field enhancement is also investigated. The maximum local electric field enhancement could be obtained with smaller thickness of dielectric layer and higher surrounding dielectric function. Our study provides a way to analyze optical properties of GDS and SDG nanotube and also broaden their applications in sensor and optical data storage. [ABSTRACT FROM AUTHOR]

The natural modes (eigenmodes) of graphene-covered circular dielectric micro-cylinders are studied based on the corresponding full-wave electromagnetic eigenvalue problem, in which complex resonance frequencies and corresponding fields are determined numerically. It is shown that the set of complex frequencies splits into two families. The first one corresponds to the modes of the dielectric cylinder perturbed by the graphene cover and the second family represents modes of the graphene cover itself which are plasmon modes. By introducing a transition coefficient, the transformation of the natural modes of the bare dielectric cylinder to the modes of the graphene and the perfectly electric conducting cylinder filled with dielectric are traced. In particular it was shown that the plasmon modes appear not only as a result of the transformation of the inner modes of the perfectly conducting cylinder but also of outer complex modes when the transition coefficient varies from zero to one. In the paper the natural modes are analyzed together with the two-dimensional scattering problem where the cylinder is excited by the H-polarized plane wave. The total and backward scattering cross-sections and the absorption cross-section versus the frequency are presented. It is shown that resonances in the behavior of these cross-sections strongly correlate with the complex frequencies of the natural modes. For a cylinder radius in the micrometer range the principal-mode resonances lay in the THz range. Consequently an important application is sensing at THz frequencies, via measuring the environment-dependent resonance frequencies. [ABSTRACT FROM AUTHOR]

In this paper, we report accurate first-principles variational rovibrational spectra predictions for the three double deuterated ethylene isotopologs denoted as cis, trans, and as-12C2H2D2. Calculations were performed in the framework of the normal-mode approach using our ab initio12C2H4 (D2h) Born-Oppenheimer potential energy and dipole moment surfaces. Symmetry breaking effects under bideuterated H → D substitutions (D2h → C2v/C2h) and their impact on infrared spectra are studied from normal mode transformations. All theoretical spectra simulated at 296 K up to J = 38 are in good agreement, both for line positions and in absorption cross sections, with the experiment. Accurate theoretical line lists providing for the first time intensities of rovibrational transitions are computed for the three species in the range (0–4500) cm−1 and will be available on our TheoReTS information system (http://theorets.univ-reims.fr and http://theorets.tsu.ru). These results can be used for remote sensing retrieval of isotopic species using predicted line intensities and experimentally optimized line positions. [ABSTRACT FROM AUTHOR]

The radiative forcing of dust particles in Earth atmosphere is still poorly characterized. A better estimation of the absorption cross section of dust particles in the UV-visible part of the spectrum is thus needed. Among the methods used for this purpose, the Atomic Point Dipole Interaction model has the distinctive advantage of being sensitive to the atomistic geometry of the particle and to the chemical functions it contains. However, this requires an adequate parameterization of the atomic polarizabilities for all the atomic species forming the particle, over the UV-visible spectrum. In this paper, we illustrate how new methodological improvements based on quantum chemistry, allow taking into account the curvature of the carbon network in the parametrization of the carbon atomic polarizabilities, using the C 60 molecule to fit the adequate set of parameters. We thus show how this leads to significant differences in the computed curves of the absorption cross section of pure carbonaceous nanoparticles as a function of the frequency, with respect to calculations performed using parameters issued from graphite. [ABSTRACT FROM AUTHOR]

Stratospheric temperature adjustment (STA) is often a significant component of greenhouse gas radiative forcing (RF), for both the most widely used definition of RF and effective radiative forcing. It is well established that the magnitude and sign of STA differs among greenhouse gases, being negative (at the tropopause) for CO2 increases (because it induces a cooling of the stratosphere) and positive for many halocarbons (because they induce a warming of the stratosphere); this effect is strongly related to the opacity (and hence the effective emitting temperature) of the troposphere at the wavelengths at which gases absorb. Here the spectral variation of STA is examined for the first time by systematically imposing a weak absorber in each of 300 bands of a narrow‐band radiation code. For this weak absorber, STA is negative for wavelengths greater than about 13 μm and positive in the 8‐ to 13‐μm "window" except in the vicinity of the 9.6‐μm ozone band. By combining narrow‐band and line‐by‐line model results, these findings are used to improve a widely used fast method to estimate radiative efficiency (RE, the RF per unit change in concentration) directly from laboratory measurements or theoretical calculations of halocarbon absorption cross sections; the new method reproduces detailed RE calculations to better than 1.4%. This is a significant improvement over a cruder method used to account for STA in RE tabulations in the Intergovernmental Panel on Climate Change's Fifth Assessment Report, which were used to calculate metrics such as the Global Warming Potential, for halocarbons and related substances. Plain Language Summary: Increased emissions and concentrations of greenhouse gases, due to human activity, are a major driver of climate change. Carbon dioxide is the most important such gas, but many other gases are emitted which, collectively, contribute significantly to climate change. This paper focuses on methods to calculate the climate impact of halocarbons which are used in refrigeration, insulation, air conditioning, etc. This includes chlorofluorocarbons (CFCs), whose usage has been phased out because they deplete the ozone layer; hydrochlorofluorocarbons (HCFCs) which were regarded as transitional substances to replace the CFCs; and hydrofluorocarbons, which are widely used replacements for CFCs and HCFCs. It is important to quantify the climate impacts of halocarbons and to compare the relative impact of different halocarbons; this information is used in international agreements aimed at reducing greenhouse gas emissions. This paper presents an important refinement of a widely used simple method for calculating and comparing the climate impact of different halocarbons. This refinement considers the impact of these gases on temperatures in the stratosphere (i.e., altitudes of about 10–50 km); to achieve this, the paper first develops a general understanding of the way such gases influence stratospheric temperatures. The new technique is a significant improvement over previous methods. Key Points: Stratospheric temperature adjustment is an important component of the effective radiative forcing for many greenhouse gasesThe variation of the magnitude and sign of this adjustment with the wavelength at which greenhouse gases absorb is investigatedThe results are used to enhance a widely used simple method for estimating halocarbon radiative efficiency [ABSTRACT FROM AUTHOR]

The neutron borehole probe equipped with a neutron source and a system of neutron detectors is commonly used to determine porosity of geological formations. Transport of neutrons through media relies on their interaction with atomic nuclei, mainly with the process of scattering and absorption. Curves recorded by detectors for a given geological layer bordered by a medium with other neutron properties form the so-called anomalies. The course of the anomaly mainly depends on neutron properties of the bordering media and also on the measurement geometry, borehole properties, etc. The paper focuses mainly on an influence of neutron properties of bordered rock media on the course of the anomaly curve, especially near the media boundaries. In some cases of bordering media, characterized by specific neutron properties, the course of anomalies can be significantly disturbed, forming specific artifacts. The paper explains that the presence of artifacts is closely related to the properties of bordered media for both fast and thermal neutrons, i.e., the slowing down length of fast neutrons and the absorption cross section of thermal neutrons. Artifacts can be the cause of misinterpretation of the neutron rock porosity probe measurement. All considerations presented in this paper are based on results obtained from MC calculations performed using MCNP5 code (MCNP Team in X-5 Monte Carlo Team, MCNP—a general Monte Carlo N-particle transport code version 5. Los Alamos National Laboratory LA-UR-03-1987, 2008). [ABSTRACT FROM AUTHOR]

In this paper, Er3+ doped TeO 2 -ZnF 2 -BaF 2 -KF-Ta 2 O 5 tellurite glasses with low hydroxyl content (∼0.03 × 10−19 cm−3) were investigated employing both glass composition and glass melting process optimization. The Raman spectra and physical properties were characterized to analyze the structure of the glasses. Under the pumping of 980 nm LD laser, intense up-conversion fluorescence at 1.5 and 2.7 μm of samples and their lifetimes were detected and analyzed, and the related transition mechanisms with gradient-varying Er3+ doping concentrations were discussed. The maximum absorption and emission cross section at 2.7 μm was calculated to be 6.4 × 10−21 cm2 and 6.8 × 10−21 cm2, correspondingly, which were higher than those of traditional tellurite glasses. Using the calculated and measured spectroscopic parameters of bulk tellurite glass, a dual-wavelength pumping model was established to verify the feasibility of mid-infrared laser output in similar tellurite glass fiber. Experimental results support the assertion that the Er3+ doped tellurite glasses hold promise as a candidate laser gain medium for mid-infrared fiber laser systems. [ABSTRACT FROM AUTHOR]

Accelerating space–time is commonly utilized to depict the formation of pairs of black holes. This paper studies the pair production of charged scalar particles in the vicinity of an accelerating Reissner–Nordstrom black hole's event horizon. Essentially, we aim to investigate the production of particles that accompanies the creation of black hole pairs. In a near extremal state, this pair production manifests as a combination of Hawking radiation and the Schwinger effect. Under extremal conditions, only the latter effect remains. Furthermore, this research explores the influence of the acceleration parameter on the absorption cross section of scalar particles in proximity to the black hole. [ABSTRACT FROM AUTHOR]

The paper considers the methodological aspects of experiments planning on the irradiation of experimental fuel rods of a VVER-SKD reactor and analyzes the features of the concept of sequential irradiation in fast and thermal reactors. It is shown that the 149Sm accumulated at the irradiation in the BOR-60 plays the role of a burnable absorber at the initial stage of irradiation in the reflector cell of the IR-8 reactor. This absorber quickly burns out owing to large absorption cross section and its concentration gradually comes to equilibrium. Burnup of 149Sm leads to a gradual increase in the linear load of the irradiated experimental fuel rod, followed by a decrease and reaching the equilibrium irradiation regime. This effect must be considered when planning the irradiation regime for experimental fuel elements of the VVER-SKD reactor. [ABSTRACT FROM AUTHOR]

This paper studies the black hole shadow, absorption cross section, and Hawking radiation of a massless scalar field in the background of a static spherically symmetric black hole spacetime that is surrounded by a cloud of strings in Rastall gravity. Specifically, the effects of the parameters a and β on the photon sphere and shadow radii are investigated. The results show that as the negative parameter β decreases, the photon sphere and shadow radii change in an N-shape. In addition, the absorption cross section obtained after solving the massless Klein–Gordon equation is calculated using the sinc approximation and the partial waves method. We compare the absorption cross section obtained by the sinc approximation and the partial waves method, and find it to be exceptionally consistent in the mid-to-high frequency region. Furthermore, the effects of parameters a and β on absorption are examined in detail. Finally, we study in detail the effects of the parameters a, β and l on the Hawking radiation power emission spectrum of the considered black hole. It turns out that the string parameter a always suppresses the power emission spectrum, indicating that such black holes live longer when the string parameter a is increased while other parameters are fixed. [ABSTRACT FROM AUTHOR]

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In this paper, the scattering-to-absorption ratio that is a measurable factor and defined as the ratio of the scattering cross section to the absorption cross section in plasmonic core-shell nanoparticles with different shapes is investigated. The effect of various plasmonic materials on the scattering-to-absorption ratio is presented that can tune the plasmon resonance and play a key role in plasmonic solar cell efficiency improvement. In addition to using plasmonic materials as silver and gold, we use poor metals as bismuth because these types of metals are good materials for UV plasmonics. We also use semiconductor copper chloride (CuCl) in our calculations, because this material exhibits a strong exciton resonance, while the interaction between the plasmon resonance in metals and the exciton resonance in CuCl leads to new plexcitonic modes. [ABSTRACT FROM AUTHOR]

Comparison of total ozone column (TOC) measurements from ground-based Dobson and Brewer spectrophotometers and from various satellite instruments generally reveals seasonally varying differences of a few percent. A large part of these differences has been attributed to the operationally used Bass & Paur ozone cross-sections and the lack of accounting for varying stratospheric temperatures in the standard total ozone retrieval for Dobson. This paper demonstrates how the use of new ozone absorption cross sections from the University of Bremen (Weber et al., 2016), as recommended by the committee on Absorption Cross-Sections of Ozone, the application of appropriate slit functions, especially for the Dobson instrument (Bernhard et al. 2005), and the use of climatological values for the effective ozone layer temperature (Teff), e.g. from TEMIS, essentially eliminate these seasonally varying differences between Dobson and Brewer total ozone data. Applying this approach to the existing global network of Dobson spectrometers will reduce the uncertainty of their total ozone data, from previously 3 to 4% to better than 2.0% at most locations. [ABSTRACT FROM AUTHOR]

A re-evaluated data set of nitrogen dioxide (NO2) column densities over Rome for the years 1996 to 2017 is here presented. This long-term record is obtained from ground-based direct sun measurements with a MkIV Brewer spectrophotometer (serial number #067) and further reprocessed using a novel algorithm. Compared to the original Brewer algorithm, the new method includes updated NO2 absorption cross sections and Rayleigh scattering coefficients, and it accounts for additional atmospheric compounds and instrumental artefacts, such as the spectral transmittance of the filters, the alignment of the wavelength scale, and internal temperature. Moreover, long-term changes in the Brewer radiometric sensitivity are tracked using statistical methods for in-field calibration. The resulting series presents only a few (about 30) periods with missing data longer than 1 week and features NO2 retrievals for more than 6100 d, covering nearly 80 % of the considered 20-year period. The high quality of the data is demonstrated by two independent comparisons. In the first intensive campaign, Brewer #067 is compared against another Brewer (#066), recently calibrated at the Izaña Atmospheric Observatory through the Langley method and there compared to reference instrumentation from the Network for the Detection of Atmospheric Composition Change (NDACC). Data from this campaign show a highly significant Pearson's correlation coefficient of 0.90 between the two series of slant column densities (SCDs), slope 0.98 and offset 0.05 DU (Dobson units; 1.3×1015 molec.cm-2). The average bias between the vertical column densities is 0.03 DU (8.1×1014 molec.cm-2), well within the combined uncertainty of both instruments. Brewer #067 is also independently compared with new-generation instrumentation, a co-located Pandora spectrometer (#117), over a 1-year-long period (2016–2017) at Sapienza University of Rome, showing linear correlation indices above 0.96 between slant column densities, slope of 0.97, and offset of 0.02 DU (5.4×1014 molec.cm-2). The average bias between vertical column densities is negligible (-0.002 DU or -5.4×1013 molec.cm-2). This, incidentally, represents the first intercomparison of NO2 retrievals between a MkIV Brewer and a Pandora instrument. Owing to its accuracy and length, the Brewer data set collected in Rome can be useful for satellite calibration/validation exercises, comparison with photochemical models, and better aerosol optical depth estimates (NO2 optical depth climatology). In addition, it can be employed to identify long-term trends in NO2 column densities in a metropolitan environment, over two decades witnessing important changes in environmental policies, emission loads and composition, and the effect of a worldwide economic recession, to offer just a few examples. The method can be replicated on the more than 80 MkIV spectrophotometers operating worldwide in the frame of the international Brewer network. The NO2 data set described in this paper can be freely accessed at 10.5281/zenodo.4715219. [ABSTRACT FROM AUTHOR]

This paper reports on the differential, integral, momentum transfer and viscosity cross sections along with spin polarisation for elastically scattered electrons and positrons from iron atoms in the incident energy ( E i ) range 1 ≤ E i ≤ 10 4 eV. In addition, we report here systematically the details of the critical minima in the elastic differential cross sections, and the absorption and total cross sections. An optical model using a complex optical potential, composed of static, exchange, polarisation and imaginary terms, is used to solve the Dirac relativistic equation in partial-wave analysis. A comparison of our evaluated cross sections with the available experimental data and other theoretical findings shows a reasonable agreement over the studied energy range. [ABSTRACT FROM AUTHOR]

Enhancing the energy output of solar cells increases their competitiveness as a source of energy. Producing thinner solar cells is attractive, but a thin absorbing layer demands excellent light management in order to keep transmission- and reflection-related losses of incident photons at a minimum. We maximize absorption by trapping light rays to make the mean average path length in the absorber as long as possible. In chaotic scattering systems, there are ray trajectories with very long lifetimes. In this paper, we investigate the scattering dynamics of waves in a model system using principles from the field of quantum chaotic scattering. We quantitatively find that the transition from regular to chaotic scattering dynamics correlates with the enhancement of the absorption cross section and propose the use of an autocorrelation function to assess the average path length of rays as a possible way to verify the light-trapping efficiency experimentally. [ABSTRACT FROM AUTHOR]

Major evaluations have been updated in the latest release of the Evaluated Nuclear Data library (ENDF/B-VIII.0) and is the currently recommended pointwise library for criticality and depletion analysis in the open-source Monte Carlo code — OpenMC. However, the currently released OpenMC library does not yet include an accompanying windowed multipole library (WMP) that enables on-the-fly Doppler broadening. This paper revisits the windowed multipole representation and fixes a major drawback that has prevented its use for depletion analysis. The new WMP library presented in this paper explicitly treats key absorption reactions as separate channels such that proper reaction rates are provided during depletion analysis. Based on this improvement, the new WMP library is processed for ENDF/B-VIII.0 and then verified against the pointwise data through direct comparison, criticality benchmarks and fuel assembly depletion. The numerical results show good agreement and efficiency with the pointwise library. • The Windowed Multipole Library (WMP) for ENDF/B-VIII.0 has been released to support the OpenMC criticality and depletion analysis. • The current implementation of WMP library has been extended to include explicit absorption reaction cross sections in resolved resonance range. • The computational efficiency of WMP-based Doppler Broadening has been investigated against stochastic interpolation in criticality and depletion analysis. [ABSTRACT FROM AUTHOR]

Atmospheric black carbon (BC) is the strongest solar radiative absorber in the atmosphere, exerting significant influences on the earth's radiation budget. The mass absorption cross section (MAC) is a crucial parameter for converting the light absorption coefficient (σab) to the equivalent BC mass concentration (EBC). Traditional filter-based instruments, such as the AE33, use a constant MAC of 7.77 m 2 /g at 880 nm to derive the EBC, which may lead to uncertainty in the EBC. In this paper, a new method of converting σab to the EBC is proposed by incorporating the variations of the MAC attributed to the influences of the aerosol coating state. A Mie simulation showed that the MAC varied dramatically with different core sizes and shell thicknesses. We compared our new method with the traditional method during a field measurement at a site on the North China Plain. The results showed that the MAC at 880 nm was smaller (larger) than 7.77 m 2 /g for particles smaller (larger) than 280 nm, resulting in an EBC mass size distribution derived from the new method that was higher (lower) than the traditional method for particles smaller (larger) than 280 nm. The size-integrated EBC derived from the new method was 16 % higher than that derived from the traditional method. Sensitivity analysis indicated that the uncertainty in the EBC caused by the refractive index (RI) was within 35 %, and the imaginary part of the RI had dominant influence on the derived EBC. This study emphasizes the necessity to take variations of the MAC into account when deriving the EBC from σab and can help constrain the uncertainty in EBC measurements. [ABSTRACT FROM AUTHOR]

The use of cryogenic silicon as a detector medium for dark matter searches is gaining popularity. Many of these searches are highly dependent on the value of the photoelectric absorption cross section of silicon at low temperatures, particularly near the silicon bandgap energy, where the searches are most sensitive to low mass dark matter candidates. While such cross section data have been lacking from the literature, previous dark matter search experiments have attempted to estimate this parameter by extrapolating it from higher temperature data. However, discrepancies in the high temperature data have led to order-of-magnitude differences in the extrapolations. In this paper, we resolve these discrepancies by using a novel technique to make a direct, low temperature measurement of the photoelectric absorption cross section of silicon at energies near the bandgap (1.2 eV–2.8 eV). [ABSTRACT FROM AUTHOR]

Free carrier photogeneration in bulk‐heterojunction solar cells composed of blends of acceptor and donor organic semiconductors proceeds via intermolecular charge transfer (CT) states. Non‐adiabatic Marcus theory has proven valid to explain the absorption and emission of these sub‐gap states which have extremely weak emission probabilities and absorption cross sections making them difficult to probe directly using optical spectroscopy. Therefore, the CT state parameters involved in the Marcus model are often extracted from fittings on the photovoltaic external quantum efficiency (EQEPV) and electroluminescence. These two spectra are (ideally) interrelated via the so‐called reciprocity principle. In this paper, the limitations of such an approach are demonstrated, in particular the impact of simple low finesse cavity interference effects acting as an uneven spectral filter for emission and absorption. This can produce almost spurious CT state parameterization with, for example, relative errors as large as 90% in absorption coefficients obtained from EQEPV. It is shown how these limitations can be partially lifted using an iterative transfer matrix approach applied to the EQEPV. [ABSTRACT FROM AUTHOR]

A polarization-independent gas sensor based on crescent plasmonic dipole antenna loaded with graphene monolayer is introduced in this paper for environment monitoring applications. Single, dual, and four arms crescent dipoles are designed, analyzed and investigated. The proposed gas sensor has reconfigurable absorption characteristics in the wavelength range from 900 to 1600 nm which covers the different gases responses. A parametric study on the effect of the sensor dimensions and polarization of the illuminated waves on the total absorption of different gases is investigated. A graphene monolayer is used to enhance the gas molecule absorption in its unbiased state. An enhancement of the total absorption cross section (ACS) values for n = 1.4 is 1.028 × 105 nm2 for the unloaded sensor case and is 1.77 × 105 for the graphene loaded sensor case. The unloaded graphene sensor sensitivity is 630 nm/RIU, and for the graphene loaded case is 677.5 nm/RIU. Dual-polarized crescent dipole consists of two orthogonal arms is designed to maintain the same sensitivity for x- and y-polarized E-field illumination. A polarization independent gas sensor consists of four crescents dipole arms rotated with 45° is explained. An enhancement of gas absorption is achieved by using a sensor array of four-arm dipole sensor. Different array sizes loaded with graphene monolayer are investigated. The total ACS peak value is 7.84 × 106 nm2 for 6 × 6 dipole array is obtained. [ABSTRACT FROM AUTHOR]

In this paper, erbium-doped fiber amplifier (EDFA) gain flatness is studied using cascaded fiber Bragg gratings (FBGs) with different numbers. The gain characteristics are investigated in reference to the wavelength, EDFA length, erbium ion density, and erbium radius. Three host materials are used: conventional silica, fluoride, and alumino-germanosilica, depending on their absorption and emission cross section areas. The convectional silica exhibits a high gain of 38.5 dB before flattening with an in-band gain of 6.5 dB. After flattening, the gain is dropped to 29 dB with a relative gain difference of 1.3% with 10 FBGs. The bandwidth of 28.42 nm is realized with 20 and 10 FBGs while the 30 FBGs configuration achieves a slightly lower value of 25 nm. The fluoride as host material depicts a lower gain after flattening of 12 dB, minimum relative gain difference of 10% with 30 FBGs and bandwidth of 28.42 nm. The alumino-germanosilicate depicts the highest gain of 30 dB with 28 nm bandwidth flattened with a relative gain difference of 1% at 30 FBGs configuration. [ABSTRACT FROM AUTHOR]

Concentration measurements of evaporated hydrocarbon species by infrared laser absorption spectroscopy at a monodisperse droplet chain are presented. A droplet generator was installed within a flow channel and operated with cyclohexane, iso-octane, n-heptane, n-pentane and 1-butanol. The flow channel was flushed with a laminar flow of air at different temperatures. The absorption of a HeNe laser beam at λ = 3.39 μ m traversing through the flow channel at varying distances from the droplet chain was exploited to determine the vapor concentrations of the hydrocarbons. Measurements of the absorption cross sections in a heated gas cell ( T = 300 –773 K) enabled the quantification of the absorption signals from the droplet chain. Vapor concentrations were determined in planes perpendicular to the droplet chain. From the increase of vapor concentration between the planes, the evaporation rate could be determined. The evaporation rates were measured in dependence of co-flow temperature, droplet velocity, droplet generation frequency and droplet spacing. In the investigated temperature range of the air (313–430 K) the evaporation rates increased linearly with temperature. The order of the fuels with respect to evaporation rates corresponded with the boiling points of the individual fuels. In addition to the presentation of the results, the paper discusses the performance of vapor concentration measurements by laser absorption spectroscopy at droplet chains which has not been tested before in such a configuration. Particular attention was paid to the spatial resolution of the measurement. The results are well suited to validate models and numerical simulations. [ABSTRACT FROM AUTHOR]

This paper investigates the nanoscale control of heating processes in the Au nanostructures from the aspects of light sources, nanoparticle morphologies, multi-layer Au shells, and nanoparticle dimers. The spatiotemporal evolution of the temperature profile inside and around the Au nanoparticles is computed using a numerical framework based on the finite element method. One-temperature model and two-temperature model are used for the calculation of continuous-wave and picosecond pulse laser, respectively. Results show that the maximum temperature increase is linear with the laser energy density, the slopes of which are various for continuous-wave laser and picosecond pulse laser. For the Au cube, ellipsoid, ring, and sphere with the same volume, the maximum resonance wavelengths locate in ~ 580 nm, 610 nm, 500 nm, and 530 nm, respectively. The trend of the maximum temperature increase agrees well with the absorption cross section. With increasing the number of the shell, a red shift occurs from 665 to 690 nm and the total absorption cross section also increases. What needs to be emphasized is that it does not need to heat the surrounding environment while the core region remains a very high temperature, which is very interesting and suitable for photothermal applications such as photothermal catalysis and nanoreaction oven. For the nanoshell dimers, it can be heated selectively by adjusting the incident angle and light wavelength for this dimer system. [ABSTRACT FROM AUTHOR]

The averaged absorption cross section of a lossy object can be measured in a reverberation chamber (RC). Conventionally, the measurement is conducted in the frequency domain and it requires two antennas with known efficiency. In this paper, the two one-antenna methods are presented—one is in the frequency domain and the other is in the time domain. In the frequency domain, by using the enhanced backscatter effect, the measurement setup is greatly simplified and only one antenna with known efficiency is required. In the time domain, the measurement can be conducted rapidly and accurately using just one antenna and the source stir technique by considering the robustness of the chamber decay time; moreover, the RC can be replaced by a suitable electrically large conducting cavity, which will greatly reduce the hardware requirement. It is found that the time-domain approach is superior to the frequency-domain approach in many aspects. The new measurement methods are efficient and accurate, while the system requirements and setup are simpler than the conventional ones. [ABSTRACT FROM AUTHOR]

[Display omitted] • Electron momentum spectroscopy study of 1,3-dimethyladamantane. • Momentum profiles of the outer valence orbitals have been obtained with high statistical accuracy. • The momentum profiles are compared with those of adamantane to examine the effects of methyl substitution on the molecular orbitals. • The findings suggest that the substitution of methyl groups results in a more spatial delocalization of the highest occupied orbital, which consequently enhances the absorption cross section of the 3 s Rydberg excitation. This paper investigates the effects of methyl substitution on the valence orbital momentum distributions of adamantane. Kinematically complete electron-impact ionization experiments on 1,3-dimethyladamantane are performed at an incident electron energy of 1.2 keV, and the resulting electron momentum profiles are compared with those of pristine adamantane. Moreover, the influences of molecular vibration and distorted-wave effects on the electron momentum profiles are examined. The highest occupied molecular orbital (HOMO) of adamantane, 7t 2 , is split into the 10b 1 , 18a 1 , and 12b 2 orbitals in 1,3-dimethyladamantane. It is revealed that the momentum profile for the sum of the 10b 1 , 18a 1 , and 12b 2 orbitals exhibits a markedly higher intensity at low momentum than that of the 7t 2 parent orbital. This strongly suggests that the HOMO is spatially more extended when surface hydrogens are replaced with methyl groups, which causes an increase in the absorption cross section of the 3 s Rydberg excitation. [ABSTRACT FROM AUTHOR]

Black carbon (BC) is a major component of submicron particulate matter (PM), with significant health and climate impacts. Many cities in emerging countries lack comprehensive knowledge about BC emissions and exposure levels. This study investigates BC concentration levels, identifies its emission sources, and characterizes the optical properties of BC at urban background sites of the two largest high-altitude Bolivian cities: La Paz (LP) (3600 m above sea level) and El Alto (EA) (4050 m a.s.l.), where atmospheric oxygen levels and intense radiation may affect BC production. The study relies on concurrent measurements of equivalent black carbon (eBC), elemental carbon (EC), and refractory black carbon (rBC) and their comparison with analogous data collected at the nearby Chacaltaya Global Atmosphere Watch Station (5240 m a.s.l). The performance of two independent source apportionment techniques was compared: a bilinear model and a least-squares multilinear regression (MLR). Maximum eBC concentrations were observed during the local dry season (LP: eBC = 1.5 ± 1.6 µ g m−3; EA: 1.9±2.0 µ g m−3). While eBC concentrations are lower at the mountain station, daily transport from urban areas is evident. Average mass absorption cross sections of 6.6–8.2 m2 g−1 were found in the urban area at 637 nm. Both source apportionment methods exhibited a reasonable level of agreement in the contribution of biomass burning (BB) to absorption. The MLR method allowed the estimation of the contribution and the source-specific optical properties for multiple sources, including open waste burning. [ABSTRACT FROM AUTHOR]

Atmospheric aerosols strongly influence the global climate through their light absorption properties (e.g., black carbon (BC) and brown carbon (BrC)) and scattering properties (e.g., sulfate). This study presents simultaneous measurements of ambient-aerosol light absorption properties and chemical composition obtained at three large-footprint southern Asian receptor sites during the South Asian Pollution Experiment (SAPOEX) from December 2017 to March 2018. The BC mass absorption cross section (BC-MAC678) values increased from 3.5 ± 1.3 at the Bangladesh Climate Observatory at Bhola (BCOB), located at the exit outflow of the Indo-Gangetic Plain, to 6.4 ± 1.3 at two regional receptor observatories, the Maldives Climate Observatory at Hanimaadhoo (MCOH) and the Maldives Climate Observatory at Gan (MCOG), representing an increase of 80 %. This likely reflects a scavenging fractionation, resulting in a population of finer BC with higher MAC678 that has greater longevity. At the same time, BrC-MAC365 decreased by a factor of 3 from the Indo-Gangetic Plain (IGP) exit to the equatorial Indian Ocean, likely due to photochemical bleaching of organic chromophores. The high chlorine-to-sodium ratio at the BCOB, located near the source region, suggests a significant contribution of chorine from anthropogenic activities. Particulate Cl− has the potential to be converted into Cl radicals, which can affect the oxidation capacity of polluted air. Moreover, Cl− is shown to be nearly fully consumed during long-range transport. The results of this synoptic study, conducted on a large southern Asian scale, provide rare observational constraints on the optical properties of ambient BC (and BrC) aerosols over regional scales, away from emission sources. They also contribute significantly to understanding the aging effect of the optical and chemical properties of aerosols as pollution from the Indo-Gangetic Plain disperses over the tropical ocean. [ABSTRACT FROM AUTHOR]

In order to study the environment or climate of an area, it is necessary to understand the composition of atmospheric aerosol particles, as well as microphysical properties, such as extinction cross section, scattering cross section, polarization degree, etc. For a long time, when calculating the microphysical properties of atmospheric aerosol particles, the aerosol particles are always be considered as spheres. Mie theory has been used to calculate the scattering properties of spherical particles with high accuracy. However, in reality, aerosol particles are not only spherical, they have complex composition and different shapes. The influence of non-spherical aerosol particles on atmospheric radiation, scattering and absorption cannot be ignored. Therefore, it is necessary to fully understand the micro-physical characteristics of non-spherical aerosol particles for fully understand the real atmospheric environment. Until now, T-Matrix method is one of the most effective and extensive methods to study the light scattering characteristics of non-sphericalrotationally symmetric aerosol particles. In this paper, the non-spherical aerosol particles extinction section, scattering cross section,the absorption cross section are calculated using T-Matrix method. The extinction, scattering, and the absorption properties arecalculated with variety of different types aerosol particles, and compared with the properties calculated by Mie scattering theory. Itlays a foundation for more accurate simulation of the microphysical properties of aerosol particles in real atmosphere. [ABSTRACT FROM AUTHOR]

This paper discuss a possibility for using a thin-film functional coating based on transparent conducting thin films of aluminum doped zinc oxide (AZO) as a heat-eliminating material on the surface of a spacecraft. The structure of the functional coating has been chosen taking into account the plasmonic properties of AZO and silver and represents the AZO slabs with embedded silver nanoparticles deposited on AZO layer and AZO slabs with embedded silver nanoparticles deposited on thin film fused quartz layer. The paper contains COMSOL finite element simulations of the scattering cross section for thermal radiation in the IR band in the case the investigated coating deposited on a reflective aluminum film, and absorption cross section in the near UV and visible spectral bands when the coating deposited on silicon solar panels. The calculations demonstrate an increase in the scattering cross-section in the spectral band of blackbody radiation by several orders of magnitude, with the maximum in the scattering spectrum of the AZO slabs/ AZO /Al structure corresponding to the maximum intensity of the blackbody thermal radiation, which has been heated to 100 °C in the case the lattice period of the AZO slabs is equal to the resonance wavelength for AZO. Also an increase in the absorption cross-section of AZO slabs/ AZO /Si structure in visible spectral band is observed corresponding to plasmon absorption of embedded silver nanoparticles. • Plasmon effects in ZnO:Al layers can solve the thermal problems for spacecraft. • ZnO:Al is functional material with plasmon resonances in the near IR spectral band. • ZnO:Al is a heat-eliminating material on the surface of a spacecraft. • Metal nanoparticles embedded into the AZO increase the efficiency of solar panels. [ABSTRACT FROM AUTHOR]

The aim of this paper is to present a new approach, based on singular volume integral equations and a perturbative approach in order to compute the size dependency of plasmonic resonances of metallic nanoparticles when the quasistatic regime is no longer valid. The paper also provides rigorous derivations of the extinction and absorption cross sections for elliptical particles. [ABSTRACT FROM AUTHOR]

In this paper, a new methodology coupling aerosol optical and chemical parameters in the same source apportionment study is reported. In addition to results on source contributions, this approach provides information such as estimates for the atmospheric absorption Ångström exponent (α) of the sources and mass absorption cross sections (MACs) for fossil fuel emissions at different wavelengths. A multi-time resolution source apportionment study using the Multilinear Engine (ME-2) was performed on a PM 10 dataset with different time resolutions (24, 12, and 1 h) collected during two different seasons in Milan (Italy) in 2016. Samples were optically analysed by an in-house polar photometer to retrieve the aerosol absorption coefficient bap (in Mm -1) at four wavelengths (λ=405 , 532, 635, and 780 nm) and were chemically characterized for elements, ions, levoglucosan, and carbonaceous components. The dataset joining chemically speciated and optical data was the input for the multi-time resolution receptor model; this approach was proven to strengthen the identification of sources, thus being particularly useful when important chemical markers (e.g. levoglucosan, elemental carbon) are not available. The final solution consisted of eight factors (nitrate, sulfate, resuspended dust, biomass burning, construction works, traffic, industry, aged sea salt); the implemented constraints led to a better physical description of factors and the bootstrap analysis supported the goodness of the solution. As for bap apportionment, consistent with what was expected, biomass burning and traffic were the main contributors to aerosol absorption in the atmosphere. A relevant feature of the approach proposed in this work is the possibility of retrieving a lot of other information about optical parameters; for example, in contrast to the more traditional approach used by optical source apportionment models, here we obtained source-dependent α values without any a priori assumption (α biomass burning =1.83 and α fossil fuels =0.80). In addition, the MACs estimated for fossil fuel emissions were consistent with literature values. It is worth noting that the approach presented here can also be applied using more common receptor models (e.g. EPA PMF instead of multi-time resolution ME-2) if the dataset comprises variables with the same time resolution as well as optical data retrieved by widespread instrumentation (e.g. an Aethalometer instead of in-house instrumentation). [ABSTRACT FROM AUTHOR]

• The preliminary design of helium-cooled mixed bed breeder (HCMB) blanket for CFETR is performed. • The neutronics and thermal-hydraulics analyses of CFETR are performed. • The global TBR of HCMB is larger than that of HCCB. Chinese Fusion Engineering Test Reactor (CFETR) is a tokamak device designed with different power levels to validate fusion engineering technologies in China. Helium-cooled ceramic breeder (HCCB) blanket and Water-cooled ceramic breeder (WCCB) blanket are the main candidates. Compared with WCCB, HCCB generally has a higher tritium breeding ratio (TBR) because helium has smaller neutron absorption cross sections than water. However, the TBR of the HCCB decreases with the increase of the fusion power. In this paper, the preliminary neutronics and thermal-hydraulics design of the Helium-Cooled Mixed bed Breeder (HCMB) blanket is proposed. The blanket structure with a fusion power of 1.5 GW is designed based on the current HCCB design of the CFETR. The HCMB adopts helium as the coolant and the mixed Li 4 SiO 4 /Be 12 Ti as the tritium breeder. The neutronics and thermal-hydraulics performances of HCMB blanket have been analyzed in the paper. The results show that the HCMB blanket design has a TBR up to 1.25 with the thermal-hydraulics requirements satisfied. [ABSTRACT FROM AUTHOR]

The interaction of a cell with light is described by electromagnetic theory through parameters such as absorption cross-section, scattering cross-section and scattering phase function, which are essential radiative properties in radiative transfer theory for analysis of light transport in dispersed media. The radiative properties of microalgae vary with time due to the growth process of cell division and metabolism. In this paper, the growth-dependent radiative properties of Spirulina platensis (a microalgae with filamentous helix structure) was experimentally investigated in batch cultivation. The microalgae was cultivated in a flat-plate photobioreactor under dark and light cycle 12 h and 12 h with irradiance of 2000–2500 lx. The absorption and scattering cross-sections of Spirulina platensis were measured in the spectral region 380–850 nm at different growth time. The experimental results showed temporal scaling behavior of the radiative properties of this filamentous microalgae, which confirms the temporal scaling law of radiative properties of microalgae reported recently, namely, the temporal scaling function (TSF) defined as the ratio of spectral absorption or scattering cross-sections at different growth time to that at stationary phase is nearly wavelength independent. This paper is the first work on the temporal scaling behavior of radiative properties of Spirulina platensis , and also provides additional experimental evidence on the general validity of the temporal scaling law of radiative properties of microalgae cells. [ABSTRACT FROM AUTHOR]

This paper reports a systematic investigation on the optical properties of Au@Ag core-shell nanocubes as a function of the core-shell size ratio with the boundary element method (BEM).The absorption cross sections (nm2) for different light wavelengths are calculated using the full Maxwell equations. Also, the related field enhancements for Au@Ag core-shell nanocubes with an incoming plane wave with a polarization along the x-axis are computed. The surface charge at the resonance wavelength of 400 nm and then the electric fields outside and inside the core-shell nanocubes are mapped. A comparison of plasmonic modes between Au@Ag core-shell and single Ag nanocubes shows that there are minor differences between their responses where the surface plasmonic resonance peak position remains constant with varying the core-shell nanocubes ratio up to 50% in most cases under consideration. However, the maximum values of absorption cross sections increase with increasing the core-shell sizes ratio up to core-shell size ratio equal to 50%. The core-shell size ratio dependence of optical properties described here can be utilized in designing plasmonic nanostructures for applications in biosensors, nonlinear spectroscopy, near-field lithography and plasmonic solar cells. [ABSTRACT FROM AUTHOR]

In this paper, the light scattering properties for multiple silver-coated dielectric nanocylinders with the symmetrical distribution were investigated. Based on the transfer matrix method, we derive the general transmission and reflection coefficient matrices for multiple dielectric nanocylinders. When the incident light frequencies are less than the plasma frequencies, the surface plasmons (SPs) appear in the interface between the silver and dielectrics. Numerical simulations show that there are three peaks of absorption cross-section (ACS) in the relationship between the ACS and the frequencies of the incident light, when the distance between the silver-coated dielectric nanocylinders is chosen properly. These SPs resonance peaks are characterised as resonances intrinsic to the cylindrically periodic system corresponding to different inner cavity structures. These multi-resonant cavities may have potential applications in integrated devices, optical sensors and optical storage devices. [ABSTRACT FROM AUTHOR]

This paper explores the near-extremal and extremal magnetized Kerr black hole, revealing the Schwinger effect in the absorption cross section at the spacetime's extremal limit. The agreement with CFT 2 hints at hidden conformal symmetry. The analysis uncovers S L (2 , R) L × S L (2 , R) R symmetry for the massless scalar near the black hole, suggesting the Kerr/CFT correspondence for the magnetized Kerr black holes. Cardy formula of the conformal field theory is used to reproduce the black hole entropy in both extremal and near-extremal cases. [ABSTRACT FROM AUTHOR]

Surface-enhanced infrared absorption (SEIRA) spectroscopy exploits the field enhancement near nanophotonic structures for highly sensitive characterization of (bio)molecules. The vibrational signature observed in SEIRA spectra is typically interpreted as field-enhanced molecular absorption. Here, we study molecular vibrations in the near field of single antennas and show that the vibrational signature can be equally well explained by field-enhanced molecular scattering. Although the infrared scattering cross section of molecules is negligible compared to their absorption cross section, the interference between the molecular-scattered field and the incident field enhances the spectral signature caused by molecular vibrational scattering by 10 orders of magnitude, thus becoming as large as that of field-enhanced molecular absorption. We provide experimental evidence that field-enhanced molecular scattering can be measured, scales in intensity with the fourth power of the local field enhancement and fully explains the vibrational signature in SEIRA spectra in both magnitude and line shape. Our work may open new paths for developing highly sensitive SEIRA sensors that exploit the presented scattering concept. The authors study molecular vibrations in the near field of single antennas, showing that the vibrational signature in SEIRA spectra can be explained by field-enhanced molecular scattering. This opens pathways for the development of sensitive SEIRA sensors exploiting this concept. [ABSTRACT FROM AUTHOR]

Black carbon (BC) is one of the most important climate forcers with severe health effects. Large uncertainties in radiative forcing estimation and health impact assessment arise from the fact that there is no standardized method to measure BC mass concentration. This study presents a 2-year comparison of three state-of-the-art BC measurement techniques at the high-altitude research station Pic du Midi (PDM) located in the French Pyrenees at an altitude of 2877 m above sea level. A recently upgraded Aethalometer AE33, a thermal-optical analyser Sunset and a single-particle soot photometer SP2 were deployed to measure simultaneously the mass concentration of equivalent black carbon (MeBC), elemental carbon (MEC) and refractory black carbon (MrBC), respectively. Significant deviations in the response of the instruments were observed. All techniques responded to seasonal variations in the atmospheric changes in BC levels and exhibited good correlation during the whole study period. This indicates that the different instruments quantified the same particle type despite the fact that they are based on different physical principles. However the slopes and correlation coefficients varied between instrument pairs. The largest biases were observed for the AE33 with MeBC values that were around 2 times greater than MrBC and MEC values. The principal reasons of such large discrepancy were explained by the mass absorption cross section (MAC) that was too low and C values recommended by the AE33 manufacturer and applied to the absorption coefficients measured by the AE33. In addition, the long-range transport of dust particles at PDM in spring caused significant increases in the bias between AE33 and SP2 by up to a factor 8. The Sunset MEC measurements agreed within around 17 % with the SP2 MrBC values. The largest overestimations of MEC were observed when the total carbon concentrations were below 25 µgCcm-2 , which is probably linked to the incorrect determination of the organic carbon (OC)–EC split point. Another cause of the discrepancy between instruments was found to be the limited detection range of the SP2, which did not allow for the total detection of fine rBC particles. The procedure used to estimate the missing mass fraction of rBC not covered by the measurement range of the SP2 was found to be critical. We found that a time-dependent correction based on fitting the observed rBC size distribution with a multimodal lognormal distribution is needed to accurately estimate MrBC over a larger size range. [ABSTRACT FROM AUTHOR]