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In this paper, we study the critical impact parameter and Lyapunov exponent for a massive charged particle and a photon in the Kerr–Newman–de Sitter (KNdS) spacetime. From the geodesic equations obtained for the particle traveling parallel to the rotation axis (on-axis) of the KNdS spacetime and using the complex angular momentum (CAM) technique, it is found that the total absorption cross-section at a high-frequency limit oscillates with decreasing amplitude. We show that the black hole charge and spin affect the total absorption cross-section in the case of both the massive charged particle and photon. [ABSTRACT FROM AUTHOR]

In this work, we investigate the quasinormal modes (QNMs), shadow radius, gray-body factor, Hawking radiation and absorption cross-section of the Reissner–Nordström black hole surrounded by a cloud of strings in Rastall gravity for a massless scalar field. We use the sixth-order Wenzel, Kramers and Brillouin (WKB) and unstable circular null geodesic methods to calculate QNMs. Moreover, the values obtained by the two methods are in very good agreement. The real part and absolute value of imaginary part of quasinormal frequencies decrease with the increase of a. As q increases, the real part of quasinormal frequencies increases while the absolute value of imaginary part first increases and then decreases. For β > 0, they decrease with the increase of β. While they first increase and then decrease with β increasing at small value of a when β < 0. Then using the unstable circular null geodesic method, we obtain the shadow radius of black hole. We find that shadow radius decreases first and then increases as the negative parameter β increases. We also calculate the gray-body factor. According to it, Hawking radiation and absorption cross-section are calculated. We explore the influence of a, β and q on the energy emission rate. When other parameters are fixed, the black hole lives longer as a, positive parameter β and q increase. To obtain absorption cross-section, we adopt the partial wave method and sinc approximation method, and the results obtained by two methods have excellent consistency at mid-high frequency region. Further, we assess the effect of a, β and q on the absorption cross-section. [ABSTRACT FROM AUTHOR]

All thermoplasmonic applications have an objective of significantly improving the photothermal conversion of spherical plasmonic nanoparticles, but different core sizes and shell thicknesses provide challenges. In order to examine novel and potential applications, a range of photothermal nanomaterials have been improved with superior light harvesting and photothermal conversion abilities. Here present work described the optical and thermoplasmonic properties of Fe and its oxide and Al and its oxide in spherical core-shell combination with core sizes varying between 20 and 50 nm, and two different shell thicknesses of 5 and 20 nm are investigated by the Mie theory in the water surrounding medium. It is revealed that the LSPR of distinct core-shell nanoparticles could be easily improved by changing the materials and also varying the core sizes as well as the shell thickness. The optical spectra are observed in the range of 230–637 nm wavelengths and merged in the UV-visible-near-infrared region on the electromagnetic (EM) spectrum. Maximum absorption and scattering cross-section are revealed at resonance wavelengths of 442 nm (Cabs≈2.75 × 10− 14 m2), and 337 nm (Csca≈4.95 × 10− 14 m2) for 20 nm shell thickness of Al@ Fe2O3. Further, the maximum temperature at the surface of the nanoparticle is observed at 4.13 0 C of Fe@Fe2O3, and 6.50 0 C of Al@ Fe2O3 with 5 and 20 nm shell thicknesses respectively. The maximum temperature rise and absorption power or heat generation is obtained for iron and its oxide in core-shell i.e. Fe@Fe2O3 NPs in the water environment. Moreover, the order of rising maximum temperature of considered NPs in distinct core-shell is as Fe@Fe2O3 > Al@Fe2O3 > Fe@Al2O3 > Al@Al2O3. Our findings provide a way to analyze the core-shell nanoparticle's potential in optical imaging, the biomedical field, therapeutics, and thermal nano-heaters under its LSPR characteristics. [ABSTRACT FROM AUTHOR]

We study the quasinormal modes, Hawking radiation and absorption cross-section of the Bardeen black hole surrounded by perfect fluid dark matter for a massless scalar field. Our results show that the oscillation frequency of quasinormal modes is enhanced as magnetic charge g or the dark matter parameter α increases. For damping rate of quasinormal modes, the influence of them is different. Specifically, the increase of dark matter parameter α makes the damping rate increasing at first and then decreasing. While the damping rate is continuously decreasing with the increase of the magnetic charge g. Moreover, we find that the increase of the dark matter parameter α enhances the power emission spectrum whereas magnetic charge g suppresses it. This means that the lifespan of black holes increases for smaller value of α and larger value of g when other parameters are fixed. Finally, the absorption cross-section of the considered black hole is calculated with the help of the partial wave approach. Our results suggest that the absorption cross-section decreases with the dark matter parameter α or the magnetic charge g increasing. [ABSTRACT FROM AUTHOR]

In this work, we utilize the Wentzel–Kramers–Brillouin (WKB) approximation to determine the Hawking temperature corresponding to the Kerr–Newman–de Sitter (KNdS) spacetime. Specifically, we calculate the low frequency absorption cross-section for the KNdS black hole in a charged scalar field and analyzed its dependence on the characteristics of the black hole. Through our research, we have established a correlation between the absorption cross-section ( σ abs ) and the Hawking temperature ( T H ) of the black hole, demonstrating an inverse proportionality between the two quantities. Furthermore, we also deduce the absorption cross-sections for Kerr–de Sitter, Reissner–Nordstrom–de Sitter, Schwarzschild–de Sitter and Schwarzschild black holes, and compare them with previously obtained results. The validity of our findings is demonstrated by these comparisons. [ABSTRACT FROM AUTHOR]

We study the quasinormal modes, Hawking radiation and absorption cross-section of the Bardeen black hole surrounded by perfect fluid dark matter for a massless scalar field. Our results show that the oscillation frequency of quasinormal modes is enhanced as magnetic charge g or the dark matter parameter α increases. For damping rate of quasinormal modes, the influence of them is different. Specifically, the increase of dark matter parameter α makes the damping rate increasing at first and then decreasing. While the damping rate is continuously decreasing with the increase of the magnetic charge g. Moreover, we find that the increase of the dark matter parameter α enhances the power emission spectrum whereas magnetic charge g suppresses it. This means that the lifespan of black holes increases for smaller value of α and larger value of g when other parameters are fixed. Finally, the absorption cross-section of the considered black hole is calculated with the help of the partial wave approach. Our results suggest that the absorption cross-section decreases with the dark matter parameter α or the magnetic charge g increasing. [ABSTRACT FROM AUTHOR]

[Display omitted] • O 2 and O 3 absorption cross-section was acquired by eliminating the effects of conversion and nonlinearity. • The maximum ACS for O 2 and O 3 are 7.84 × 10−20, 1.32 × 10−17 cm2/molecule, respectively. • O 2 and O 3 ACS play an important role in inversion concentrations. Oxygen (O 2) and ozone (O 3) are of crucial importance to human health and environmental sustainability. Concentrations of O 2 and O 3 can be measured by UV absorption spectroscopy, in which the absorption cross-section (ACS) is a very critical physical parameter for calculating concentrations. However, the existing ACS of O 2 and O 3 are biased because the conversion of O 2 to O 3 and nonlinear effects in absorption are ignored in the measurement of ACS. In this study, the ACS for O 2 and O 3 are obtained by considering the conversion of O 2 to O 3 and the nonlinear effects. First, the conversion of O 2 to O 3 is inhibited by controlling gas flow rate and light intensity in the measurement of O 2 and O 3 ACS. Then the concentration of O 3 is indirectly calculated by controlling conversion of O 2 to O 3 during the measurement of ACS of O 3. Next, the linear-absorption regions for O 2 and O 3 are determined by constructing the relationship between absorption intensities and concentrations to eliminate the influence of nonlinear effect. The maximum ACS for oxygen and ozone are 7.84 × 10 - 20 cm2/molecule (λ = 180.51 nm) and 1.32 × 10 - 17 cm2/molecule (λ = 255.39 nm) by controlling conversion of O 2 to O 3 in the linear-absorption region, respectively. [ABSTRACT FROM AUTHOR]

• Utilizing a non-uniform temperature cell is proposed for high temperature spectroscopy. • The proposed method is validated and experimentally demonstrated. • The accuracy of the proposed method is confirmed via simulated composite spectra. • The application of the proposed method is demonstrated experimentally. • The method is expected to be instrumental for high temperature spectroscopy beyond 8 µm. A mathematical method to enable absorption cross-section measurements using an optical cell with a non-uniform temperature distribution is formulated, validated and experimentally demonstrated in this study. The motivation of the proposed method is to facilitate high-temperature spectroscopic studies in the long-wavelength mid-IR region, and to offer an alternative to highly engineered optical cells. The method is based on virtual segmentation of the non-uniform temperature field within an optical cell into bins, each having a sufficiently uniform temperature. By collecting a set of absorbance measurements corresponding to unique temperature profiles and expressing the temperature dependence of the absorption cross-section in terms of a model with limited number of unknowns, a closed-form system of equations is obtained which can be solved to evaluate absorption cross-sections. It is shown, through a set of simulated validation cases, that modeling the temperature dependence in terms of a third order polynomial results in accurate reconstruction of the cross-section spectra for a wide range of cases. Piece-wise polynomials and an alternative nonlinear model are proposed for improved accuracy and to model potentially complex temperature dependencies of the absorption cross-sections. To demonstrate the application of the proposed method, an optical cell with a non-uniform temperature profile was used to measure the cross-section spectra of methane over 1280 – 1330 cm-1 at temperatures up to 523 K. The proposed method is expected to be highly useful in collecting spectroscopic data at high temperatures particularly in the mid-infrared region. [ABSTRACT FROM AUTHOR]

This study investigates the theoretical knowledge about the absorption cross-section, heat release, and temperature change of liquid Cs-core and various shell materials by employing the Mie theory. The present work was carried out with varying Cs-core sizes, viz., 10 nm, 15 nm, 20 nm, 25 nm, and 30 nm with a fixed 5 nm shell thickness of Ag and Au, Al and its oxide (Al2O3), and Cu and its oxide (Cu2O) in the presence of the surrounding environment (i.e., water). The localized surface plasmon resonance (LSPR) peak position emerges between 299 and 1132 nm wavelengths, and the observed spectra are tuned in the vicinity of the ultraviolet (UV) and infrared (IR) domains of the electromagnetic (EM) spectrum. The maximum absorption cross-section was revealed for the 30 nm Cs-core at resonance wavelengths of 639 nm (σabs ≈2.41E − 14 m2) with a Cu shell thickness. The maximum temperature and absorption power at the surface of the nanoparticles were observed at 9.21 °C and 2476 nW for Cs@Cu at 629 nm wavelength in the water environment. Moreover, absorption cross-section spectra and heat power increased with increasing core-sizes. The E-field enhancement was highest when Cs NPs were placed in the core rather than the shell material, and the E-field values increased with decreasing Cs-core sizes. These results show that the intensity and LSPR position of peaks, heat generation, and temperature elevation are strongly influenced by varying the Cs core sizes with various shell materials. The observed results can have potential applications in thermoplasmonic devices, sensing, cancer therapy, photocatalytic activity, and Surface-enhanced Raman spectroscopy (SERS). [ABSTRACT FROM AUTHOR]

The article describes a new practical model for the infrared absorption of chlorofluorocarbons and other gases with dense spectra, based on high‐resolution transmission molecular absorption database (HITRAN) absorption cross‐sections. The model is very simple, consisting of frequency‐dependent polynomial coefficients describing the pressure and temperature dependence of absorption. Currently it is implemented for the halocarbon species required by the Radiative Forcing Model Intercomparison Project. In cases where cross‐section data is available at a range of different temperatures and pressures, this approach offers practical advantages compared to previously available options, and is traceable, since the polynomial coefficients follow directly from the laboratory spectra. The new model is freely available and has several important applications, notably in remote sensing and in developing advanced radiation schemes for global circulation models that include halocarbon absorption. For demonstration, the model is applied to the problem of computing instantaneous clear‐sky halocarbon radiative efficiencies and present day radiative forcing. Results are in reasonable agreement with earlier assessments that were carried out with the less explicit Pinnock method, and thus broadly validate that method. Plain Language Summary Chlorofluorocarbons and other related gases have dense and complicated absorption spectra that can be measured in the laboratory. We bring such measurements to a form that can be used for simulations of the transfer of radiation through the atmosphere. Then we use the new model to calculate new estimates of the climate impact of these man‐made gases. The results broadly validate earlier calculations that were done with a less explicit method. Plain Language Summary: Chlorofluorocarbons and other related gases have dense and complicated absorption spectra that can be measured in the laboratory. We bring such measurements to a form that can be used for simulations of the transfer of radiation through the atmosphere. Then we use the new model to calculate new estimates of the climate impact of these man‐made gases. The results broadly validate earlier calculations that were done with a less explicit method. Key Points: A new polynomial model for laboratory absorption cross‐section data was developedThe new model was used to compute instantaneous clear‐sky halocarbon radiative efficiencies and present day radiative forcingHalocarbons are found to contribute approximately 20% of the total anthropogenic instantaneous clear‐sky forcing [ABSTRACT FROM AUTHOR]

An influence of the adsorbed molecules layer on the optical characteristics of the spherical metallic nanoparticles has been studied in the work. In order to do this one considers the additional term which takes into account the scattering of electrons at the interface between metal and adsorbate. The analytical expressions for the frequency dependences for the parameter of coherence loss due to the scattering at the interface "metal - adsorbed layer" have been obtained. It has been found that the presence of the adsorbed molecules results in the electron scattering anisotropy, and, hence, in the anisotropy of the optic response of such systems. The result of the indicated anisotropy is the appearance of the additional maximum in the infrared part of the spectrum in the frequency dependences for the optical characteristics. An evolution of the frequency dependences for the components of the polarizability tensor and the absorption cross-section and scattering cross-section for the two-layer spherical nanoparticles of the type "metal - adsorbate" under the variation of their geometrical parameters has been analyzed. It has been shown that the weak maximum of the real, imaginary parts and the module of the transverse component of the polarizability tensor and the absorption and scattering cross-sections in the infrared part of the spectrum appears due to inducing of the local density of the states by adsorbate. The reason of the shift of the maxima of the absorption cross-section and scattering cross-section for the nanoparticles of the constant sizes with the cores of different metals has been found. It has been demonstrated the existence of the small-scale oscillations at the frequency dependences for the components of the polarizability tensor and at the absorption and scattering cross-sections, caused by an oscillating contribution of the surface electron scattering. The dependence of the location and the value of the maximum of the absorption cross-section for the particle "metal - adsorbate" with the constant geometrical parameters and content on the dielectric permittivity of the medium, in which the nanoparticle is situated, has been proved. [ABSTRACT FROM AUTHOR]

The behavior of the diagonal components of the dielectric tensor and the behavior of the absorption crosssection in the different frequency ranges for the composite cylindrical nanostructures "metallic core - graphene shell" have been studied. In order to obtain the calculation formulas one uses the relations for the longitudinal and transverse components of the dielectric tensors for metallic core and graphene shell, which are determined by Drude model and Cubo model correspondingly. The consideration is carried out in the frameworks of "equivalent" elongated spheroid approach, according to which the defining dimensional parameter is effective aspect ratio, calculated from the condition of the equality of the corresponding axial inertia moments for two-layer cylinder and the "equivalent" elongated spheroid. The numerical results have been obtained for the nanocylinders with the cores of different metals, different radius and with the different number of graphene layers. The variation of amplitude and the variation of the location of extremes of the real and imaginary parts of the transverse component of the dielectric tensor under the increase in radius of the metallic core and the thickness of the graphene shell have been analyzed. It has been shown that the variation of the radius of the core has the significantly greater influence on the properties of the polarizability resonances and absorption cross-section than the variation of the number of graphene layers. The reasons of the presence of two maxima of the absorption cross-section for the metal-graphene cylinders which differ in both amplitude and width and located in infrared, violet and near ultraviolet parts of the spectrum and their relation with the surface plasmonic resonances in the metallic core and with the terahertz plasmons of graphene have been found. The factors which have an effect on amplitude and on the shift of the maxima of the absorption cross-section have been found. The reasons of the different width of maxima, which are located in the different spectral intervals, have been determined. [ABSTRACT FROM AUTHOR]

Single-stage processing of high-quality transparent functional polycrystalline ceramics is desirable but challenging. In the present work, spark plasma sintering (SPS) was employed for fabrication of Co2+:MgAl 2 O 4 saturable absorbers for laser passive Q-switching. Densification of commercial MgAl 2 O 4 powders, doped via co-precipitation, was carried out by conventional SPS and high-pressure SPS (HPSPS) under pressures of 60 and 400 MPa, respectively. The presence of LiF, a common sintering additive, was detrimental to optical properties as it promoted reaction of cobalt with sulfur impurities and the formation of Co 9 S 8 inclusions. Densification by HPSPS without LiF allowed to obtain highly transparent Co2+:MgAl 2 O 4. The optical properties of samples, with doping concentrations varying between 0.01 and 0.1 at.% Co2+, were assessed and saturable absorption was demonstrated at ~1.5 µm wavelength, exhibiting ground-state (σ gs) and excited (σ es) cross-sections of 3.5×10-19 and 0.8×10-19 cm2, respectively. Thus, it was established that HPSPS is an effective method to fabricate transparent Co2+:MgAl 2 O 4 ceramics. • Commercial MgAl 2 O 4 nano-powders were doped with Co2+ by co-precipitation. • Highly transparent 0.01–0.1 at% Co2+:MgAl 2 O 4 ceramics were fabricated by HPSPS. • Conventional SPS was not a viable method to produce Co2+:MgAl 2 O 4 ceramics. • LiF sintering additive induced reaction of Co with S which formed Co 9 S 8 inclusions. • HPSPS-processed Co2+:MgAl 2 O 4 can serve as laser passive Q-switch medias. [ABSTRACT FROM AUTHOR]

Plasmonic metal nanoparticles (NPs) have been proposed for many applications because of their fascinating optical properties related to the surface plasmon resonance (SPR) phenomenon. Due to the absorption of incident light, these objects are heated, intentionally or not, which may lead to the modification of their optical properties. In this study, the thermal variations of the absorption and scattering cross-sections of a gold NP are studied for different shapes and sizes. The results reveal that, in general, the SPR peak undergoes a redshift and its magnitude changes with increasing temperature. The maximum thermal variation of the NP optical properties is located around the SPR wavelength. Depending on the size and shape of NPs, these behaviors result in different profiles like valley-peak, valley, or peak, in the thermo-absorption and thermo-scattering spectra around the SPR wavelength. The results show that depending on the size and shape of NP, absorption and scattering cross-section thermal variation at SPR wavelength vary from − 14 × 10−2 to 19 × 10−2% per Kelvin. The thermal response of the differential far-field scattering is also investigated. Once again, the maximum values of the scattered far field and its thermal variation are found around the SPR wavelength, but there is no isotropic behavior; while they are uniform in the plane perpendicular to the incident electric field, they exhibit an angular dependence in the plane including the incident wave vector and electric field. [ABSTRACT FROM AUTHOR]

• Absorption non-uniformities within aggregates increase with increasing aggregate sizes, and may contribute to excessive absorption and anomalous cooling effects observed in TiRe-LII experiments on metal nanoparticles. • For the aggregates considered, primary particles within the aggregate may be shielded from the E-field at certain orientations leading to a larger degree of absorption and emission non-uniformity, however, orientation has a less than 10 % impact on the random orientation value. • Sintering-induced overlap can enhance the absorption properties of the aggregate due to increased electrical conductivity and morphological changes towards an elongated structure that promotes the antenna effect. Analyzing time-resolved laser-induced incandescence (TiRe-LII) data from metal nanoparticle aerosols requires a detailed understanding of their absorption and emission characteristics. This work investigates how non-uniform absorption within metal nanoparticle aggregates, aggregate morphology and orientation, and sintering of primary particles may affect TiRe-LII signals from metal nanoparticle aerosols. The multi-sphere T-matrix method is used to compute the absorption properties of aggregates with point contact between primary particles, while the discrete dipole approximation method is used when primary particles overlap. It was found that absorption non-uniformities within aggregates increase with increasing aggregate sizes, and may contribute to excessive absorption and anomalous cooling effects. For the anisotropic aggregates considered, the total absorption cross-section depends weakly on orientation. It was also found that the sintering of primary particles can enhance the absorption cross-section of metal aggregates. [ABSTRACT FROM AUTHOR]

Plasmonic interaction of nanoparticles located in close proximity, embedded in breast tissue, is simulated for estimating the optical characteristics like optical absorption cross-section, plasmonic wavelength as well as full-width half maxima (FWHM). The computations are done for the monomers, homodimers, and heterodimers of spherical and rod-shaped gold nanoparticles considering various interparticle spacings for gold nanospheres and the interparticle spacing as well as the orientation for gold nanorods (GNRs). The results indicate that for the spherical dimer, with the change in interparticle spacing from 1 to 20 nm, the peak absorption cross-section decreases by 43%. Whereas for the GNRs, the absorption cross-section increases/decreases, within 9–18%, depending on the homodimer or heterodimer configuration. Furthermore, secondary peaks for the absorption cross-section are obtained within wavelengths of 630–940 nm due to antibonding modes for GNR heterodimers. For GNR heterodimer located end-to-end, this secondary peak for the absorption cross-section appears at 780 nm irrespective of interparticle spacing within 1–5 nm. The absorption coefficient is considerably dependent on the configuration and proximity of GNRs located within the tissue. While FWHM is not significantly influenced by GNRs configuration and interparticle spacing. For interparticle spacing from 1 to 20 nm, the plasmonic wavelength shifts by 38 nm for the spherical dimer and by 35–86 nm for various GNR dimers. The findings of this study are useful for plasmonic photothermal therapeutics as the heat generation is governed by the resulting absorption cross-section due to plasmonic coupling of the closely spaced and different orientations of the nanoparticles. [ABSTRACT FROM AUTHOR]

The problem of absorption by a resonator of a gravity wave that propagates on the surface of an incompressible fluid is solved. The resonator is small as compared with the wavelength. For the free fluid surface the resonance, i.e., maximally possible, absorption cross-sections of resonators of various types are found. It is shown that the resonance absorption cross-section depends only on the wavelength. The problem of absorption of a gravity wave propagating in a channel is also considered. It is shown that the joint usage of monopole and dipole resonators ensures the total absorption of wave energy in the channel whose width is not greater than the wavelength. [ABSTRACT FROM AUTHOR]

In this paper, we investigated the effect of shape and size of core on the plasmonic response of spherical ZnO@Au core-shell nanostructures embedded in a passive host matrices of MgF2 within the framework of the qausistatic approximation. The absorption cross-section and local field enhancement factor of spherical ZnO@Au core-shell nanostructures are effectively studied by optimizing the parameters for a fixed composite diameter of 20 nm. In this two-layered core-shell nanostructures, four plasmonic resonances are found; the first two resonances associated with ZnO/Au and Au/MgF2 interfaces, whereas the third and fourth resonances are associated with the transverse and longitudinal modes, respectively. The peaks position and intensity of these resonances are varied by optimizing the shape and size of the core material. The tunability of the plasmon resonances of the composite systems enables it to exhibit very interesting material properties in a variety of applications extending from the visible to infrared spectral regions. [ABSTRACT FROM AUTHOR]

The analysis of the photoabsorption spectra of molecules shows that the band maximum is usually redshifted in comparison to the vertical excitation. We conducted a throughout analysis of this shift based on low-dimensional analytical and numerical model systems, showing that its origin is rooted in the frequency change between the ground and the excited states in multidimensional systems. Moreover, we deliver a benchmark of ab initio results for the shift based on a comparison of vertical excitations and band maxima calculated with the nuclear ensemble approach for the 28 organic molecules in the Mülheim molecular dataset. The mean value of the shift calculated over 60 transitions is 0.11 ± 0.08 eV. The mean value of the band width is 0.32 ± 0.14 eV. [ABSTRACT FROM AUTHOR]

Perfluoro-n-propane, perfluorocyclobutane, perfluoro-n-butane, and perfluoro-n-pentane are non-ozone-depleting industrial alternatives to chlorofluorocarbons and hydrochlorofluorocarbons. However, these perfluoroalkanes have significant band strength in the atmospheric window from 800 to 1200 cm−1. Coupled with their millennial-scale atmospheric lifetimes, they can lead to significant long-term global warming. Infrared spectra are required to quantify the climate impacts. This work provides a set of high-temperature infrared absorption cross-sections in the range 298–350 K at 0.1 cm−1 resolution from 515 to 1500 cm−1 for each compound. Our cross-sections generally agree with literature measurements except for perfluoro-n-pentane. We use density functional theory to calculate the absorption cross-sections from 0 to 515 cm−1 using the B3LYP functional and several basis sets. The 6-31G(d,p) basis set provides the best results for linear perfluoroalkanes, while the def2-TZVP basis set provides the best results for cyclic perfluoroalkanes. Using experimental cross-sections, we calculate the radiative efficiency and global warming potential for each compound, utilizing the Pinnock curve from Shine and Myhre (2020) and atmospheric lifetimes from Hodnebrog et al. (2020). These quantities are found to be independent of temperature. The average 100-year global warming potential derived from all cross-sections is 9,610±1,260, 10,800±1,420, 10,100±1,330, and 9,380±1,230 for perfluoro-n-propane, perfluorocyclobutane, perfluoro-n-butane, and perfluoro-n-pentane, respectively. Combining the data in this work with our previous measurements reveals that the global warming potential for perfluoroalkanes with an increasing number of C F bonds depends on the ratio of radiative efficiency to molecular weight. [Display omitted] • Measured n-C 3 F 8 , n-C 4 F 10 , and n-C 5 F 12 cross-sections from 515–1500 cm−1 and 298–350 K. • Improved n-C 5 F 12 cross-sections compared to literature using a 99% pure sample. • Determined conformer populations for all compounds using density functional theory. • Investigated band strength and climate metrics trends with an increasing number of C F bonds. • Showed temperature independence of integrated cross-sections and climate metrics. [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]

This work presents broadband spectrally resolved measurements of the absorption cross-section of NO 2 from approximately 430 to 500 or 580 nm, depending on temperature, with a spectral resolution of approximately 0.06 nm. An ultrafast-laser-absorption-spectroscopy (ULAS) diagnostic was developed and used to provide broadband (up to approximately 900 cm−1 per laser shot) cross-section measurements with sub-nanosecond time resolution. Cross-section measurements were acquired from 430 to 580 nm in a heated gas cell at temperatures of 296 K and 670 K and a pressure of 1.5 bar. Cross-section measurements were also acquired behind reflected shock waves at temperatures near 970 K, 1150 K, and 1450 K at pressures near 1.5 bar. A quantum-cascade-laser-absorption diagnostic for NO was used to measure NO mole fraction at 500 kHz and determine the extent of NO 2 decomposition in shock-tube experiments. The measured cross-sections typically exhibit good agreement with prior measurements available at select wavelengths and conditions as well as with recently developed theoretical predictions at most wavelengths and temperatures studied. A detailed description of the experimental and data processing procedures that enabled the ULAS measurements despite pronounced variations in laser pulse energy and the absence of non-resonant wavelengths within the pulse bandwidth are also presented. • Femtosecond absorption spectroscopy measurements of NO 2 at high temperatures. • Broadband absorption cross-section measurements of NO 2 from 430 to 500 nm. • First broadband absorption cross-section measurements of NO 2 reported at up to 1450 K. [ABSTRACT FROM AUTHOR]

Optical transition and near-infrared upconversion luminescence properties of Er3+ single-doped and Er3+, Yb3+ co-doped YNbO 4 phosphors are reported. Based on the framework of Judd-Ofelt theory and modified Judd-Ofelt calculation method, the optical transition properties of Er3+ and Yb3+ ions in YNbO 4 : Er3+, Yb3+ sample were studied, respectively. The calculated results showed that the absorption cross-section of Er3+ ion at ∼1550 nm is larger than that at ∼980 nm in YNbO 4 : Er3+ phosphor. And, the absorption cross-section of 2F 7/2 → 2F 5/2 transition of Yb3+ in YNbO 4 : 15.0 mol% Er3+, 15.0 mol% Yb3+ sample was calculated to be 138.70 × 10−20 cm2. According to the emission cross section of Er3+ (4I 11/2 → 4I 15/2) and the absorption cross section of Yb3+ (2F 7/2 → 2F 5/2), the energy transfer rates from Er3+ to Yb3+ were quantitatively analyzed via the Föster-Dexter model. Furthermore, 1550 nm was selected as the excitation wavelength, the near-infrared upconversion emission spectra of YNbO 4 : Er3+, Yb3+ samples were measured. It was found that the sample has strong emission at ∼980 nm and the emission intensity was still enhanced with the incorporation of Yb3+. • YNbO 4 : Er3+, Yb3+ phosphors were synthesized via a solid-state reaction method. • The absorption cross section of Yb3+ in YNbO 4 phosphor was confirmed. • The energy transfer rates from Er3+ to Yb3+ in YNbO 4 phosphors were calculated. • The YNbO 4 : Er3+, Yb3+ sample has strong ∼980 nm emission excited by 1550 nm. [ABSTRACT FROM AUTHOR]

Abstract The electronic structures of triplet S 2 ground and excited states are studied by ab initio molecular orbital and configuration interaction calculation. Potential energy curves correlated with S ( 3 P) + S ( 3 P) and S ( 3 P) + S ( 1 D) at the dissociation limit are evaluated, and electronic terms for a total of 11 states are assigned. Transition dipole moments, as a function of internuclear distance, are determined for two allowed transitions to B ″ 3 Π u and B 3 Σ u - excited states. The total absorption cross-sections are computed to estimate isotope-fractionation constants, ε , for four most common isotopologues: 32 S 32 S , 32 S 33 S , 32 S 34 S , and 32 S 36 S by quantum close-coupling (R-matrix) expansion approach and they are found to lie in a mostly opaque to competing absorbers spectral window. We suggest that the photochemistry and isotopic effects of S 2 are of significant importance and provide data showing high sensitivity of mass-independent fractionation to excitation wavelength. Zero-point energy based constants ε ZPE are estimated as well to compare with the obtained isotope effects and two modes for MIF are present in three-isotope plots; large isotopic effects were observed for both 36 S and 33 S with an excitation wavelength-dependent fluctuation. [ABSTRACT FROM AUTHOR]

Spectrally resolved ultraviolet (UV) absorption cross-sections of gas-phase sodium chloride (NaCl), potassium hydroxide (KOH), and sodium hydroxide (NaOH) were measured, for the first time, in hot flue gases at different temperatures. Homogenous gas-phase NaCl, KCl (potassium chloride), NaOH, and KOH at temperatures 1200 K, 1400 K, 1600 K, and 1850 K were prepared in the post-flame zone of laminar flames by seeding nebulized droplets out of aqueous solution of corresponding alkali species. The amount of droplets seeded into the flame was kept constant, so the relative concentration of different alkali species can be derived. The broadband UV absorption cross-section of KCl vapor reported by Leffler et al. was adopted to derive the absorption cross-section curves of NaCl, NaOH, and KOH with the corresponding measured spectrally resolved absorbance spectra. No significant changes in the spectral structures in the absorption cross-sections were found as the temperature varied between 1200 K and 1850 K, except for NaOH at around 320 nm. The difference between the absorption spectral curves of alkali chlorides and hydroxides is significant at wavelengths above 300 nm, which thus can be used to distinguish and obtain the concentrations of alkali chlorides and hydroxides in the broadband UV absorption measurements. [ABSTRACT FROM AUTHOR]

HFC-43-10mee (C 5 H 2 F 10 ) is a substitute for CFC-113, HCFC-141b and methyl chloroform, as well as an alternative to perfluorocarbons with high radiative efficiencies. Recent observations have shown that the global mean tropospheric abundance of HFC-43-10mee has increased steadily from the 1990s to reach 0.211 ppt in 2012. To date, the emission of this compound is not regulated. The radiative efficiency (RE) of HFC-43-10mee has recently been re-evaluated at 0.42 W m −2 ppb −1 , giving a 100-year time horizon global warming potential (GWP 100 ) of 1650. However, the initial RE, from which the new values were derived, originated from an unpublished source. We calculated a new RE of 0.36 W m −2 ppb −1 and a GWP 100 of 1410 from laboratory absorption cross-section spectra of a pure vapour of HFC-43-10mee. Acquisitions were performed in the 550–3500 cm −1 spectral range using Fourier transform spectroscopy. The results were compared with the broadened spectra from the Pacific Northwest National Laboratory (PNNL) database and with theoretical calculations using density functional theory. [ABSTRACT FROM AUTHOR]

This paper presents a method for determination of the size distribution for diamond nanocrystals containing luminescent nitrogen-vacancy (NV) centers using the luminescence intensity only. We also revise the basic photo physical properties of NV centers and conclude that the luminescence quantum yield of such centers is significantly smaller than the frequently stated 100%. The yield can be as low as 5% for centers embedded in nanocrystals and depends on their shape and the refractive index of the surrounding medium. The paper also addresses the value of the absorption cross-section of NV centers. [ABSTRACT FROM AUTHOR]

Perfluoro-n-hexane and perfluoro-2-methylpentane are fully fluorinated alkanes used as non-ozone-depleting alternatives to chlorofluorocarbons and hydrochlorofluorocarbons. These compounds are long-lived and potent greenhouse gases due to their strong C F bonds and infrared absorption in the atmospheric window. Infrared absorption cross-sections are required to quantify the climate impact of these compounds via the radiative efficiency and global warming potential. To our knowledge, there are only two experimental measurements for perfluoro-n-hexane, and there are no experimental measurements for perfluoro-2-methylpentane in the infrared. In this work, we provide a set of absorption cross-sections in the range 515–1500 cm−1, at 0.1 cm−1 resolution from 298 to 350 K for each compound. We calculate the absorption cross-section between 0 and 515 cm−1 using density functional theory with various basis sets. The 6-31,G(d,p) basis set with the B3LYP functional is found to provide the best results. Using both measurements and calculations combined, we calculate the radiative efficiency and global warming potential for each compound. No significant temperature dependence was observed in these quantities. The average radiative efficiency derived from all cross-sections is 0.48 ± 0.06 W m−2 ppbv−1 for perfluoro-n-hexane and 0.46 ± 0.06 W m−2 ppbv−1 for perfluoro-2-methylpentane. The average 100-year global warming potential derived from all cross-sections is 9590 ± 1260 for perfluoro-n-hexane and 9220 ± 1210 for perfluoro-2-methylpentane. [Display omitted] • Obtained first measurements of the cross-sections of i C 6 F 14 from 515 to 1500 cm−1. • Measured cross-sections of n C 6 F 14 and confirmed the peak at 1255 cm−1. • Performed DFT calculations for all major C 6 F 14 conformers and determined their populations. • Derived global warming potentials of 9590 ± 1260 and 9220 ± 1210 for n C 6 F 14 and i C 6 F 14. • Showed temperature independence of integrated cross-sections and climate metrics. [ABSTRACT FROM AUTHOR]

The electronic structures of triplet S 2 ground and excited states are studied by ab initio molecular orbital and configuration interaction calculation. Potential energy curves correlated with S( 3 P) + S( 3 P) and S( 3 P) + S( 1 D) at the dissociation limit are evaluated, and electronic terms for a total of 11 states are assigned. Transition dipole moments, as a function of internuclear distance, are determined for two allowed transitions to 1 3 Π u and 1 3 Σ u - excited states. Furthermore, the total absorption cross-sections are computed to estimate isotope-fractionation constants, ε , for four most common isotopologues: 32 S 32 S, 32 S 33 S, 32 S 34 S, and 32 S 36 S by quantum close-coupling (R-matrix) expansion approach. Zero-point energy based constants ε ZPE are estimated as well to compare with the obtained isotope effects. Three-isotope plots are shown to express mass-independent fractionation effect; large isotopic effects were found on 36 S and 33 S in 230–240 nm range, and only on 36 S in 240–267 nm range. [ABSTRACT FROM AUTHOR]

We measured physical properties and optical properties of the black carbon (BC) generated in a spark discharger which did not produce soluble organic fractions. Effective densities and absorption cross-sections of the fresh BC were estimated using the electrical mobility diameter, the number concentration and the mass concentration. Size distribution measurements using a differential mobility analyzer (DMA) and a condensation particle counter (CPC) showed that the mode diameter and the number concentration increased with increasing spark frequency of the spark discharger. The primary particle size was also measured through the analysis of images observed using a field emission scanning electron microscope (FESEM), decreasing from 36.3 to 15.1 nm with increasing a spark frequency. The effective densities were estimated from 0.054 to 1.392 g/cm 3 and compared to be lower than those of atmospheric aerosols which might be aged. The absorption cross-sections were estimated as 1.0×10 –15 to 1.7×10 –15 m 2 depending on spark frequency. For the BC generated at a fixed constant spark frequency, the absorption cross-section was estimated to be larger as the BC became bigger in electrical mobility diameter. For the BC having the same electrical mobility diameter generated at different spark frequencies, however, the absorption cross-section generated at a faster spark frequency was smaller. Fractal dimension for the BC larger than 160 nm was measured to be 1.79, which is very similar to that for the spark-generated BC studied by other research group. In conclusion, the effective density allowed us to distinguish the core BC from aged BC. [ABSTRACT FROM AUTHOR]

[Display omitted] Absorption cross-sections for the 5th (6 ← 0) and 6th (7 ← 0) OH overtones for gas-phase methanol, ethanol, and isopropanol were measured using a slow flow cell and Incoherent Broadband Cavity-Enhanced Absorption Spectroscopy (IBBCEAS). Measurements were performed in two wavelength regions, 447–457 nm, and 508–518 nm, using two different instruments. The experimental results are consistent with previous computational predictions of the excitation energies for these transitions. Treating the OH stretch as a local mode allowed for calculation of the fundamental vibrational frequency (ω e), anharmonicity constant (ω e x e), and the vertical dissociation energy (VDE) for each alcohol studied. The fundamental vibrational frequency is 3848 ± 18 cm−1, 3807 ± 55 cm−1, and 3813 ± 63 cm−1 for methanol, ethanol, and isopropanol, respectively. The anharmonicity constant was measured to be 84.8 ± 2.1 cm−1, 80.2 ± 5.9 cm−1, and 84.4 ± 6.8 cm−1 for methanol, ethanol, and isopropanol, respectively. The OH vertical dissociation energy was measured to be 499.4 ± 18.4 kJ/mol, 518.0 ± 56.7 kJ/mol, and 492.7 ± 59.9 kJ/mol. The spectroscopically measured values are compared to thermodynamically measured OH bond dissociation energies. The observed differences in previous measurements of the bond dissociation energies compared to the values reported herein can be explained due to the difference between vertical dissociation energies and bond dissociation energies. If the OH overtone stretching mode is excited in methanol to either the 5th or 6th overtone, the bimolecular reaction between methanol and O 2 becomes thermodynamically feasible and could contribute to formation of methoxy and HO 2 radical under the proper combination of pressure and temperature. [ABSTRACT FROM AUTHOR]

Perfluoroalkanes are fully fluorinated greenhouse gases. These compounds are chemically inert due to their C–F bonds and therefore have atmospheric lifetimes of thousands of years. Although regulated under the Kyoto Protocol, atmospheric concentrations of perfluoroalkanes have continued to increase since 1997. To quantify the climate impact of perfluoro-n-heptane and perfluoro-n-octane, spectral data are required to calculate climate metrics such as the radiative efficiency and global warming potential. Experimental measurements are scarce for these compounds and are only available at 296 and 297 K. In this work, a set of absorption cross-sections is provided in the range 515–1500 cm−1 at 0.1 cm−1 resolution for nine temperatures between 300 and 350 K. There is general agreement between literature values and the absorption cross-sections and climate metrics measured in this work. These quantities do not show significant temperature dependence. The temperature averaged radiative efficiency is 0.50 ± 0.06 and 0.54 ± 0.07 Wm−2ppbv−1 for n–C 7 F 16 and n–C 8 F 18 , respectively. The temperature averaged 100-year global warming potential is 8738 ± 1149 for n–C 7 F 16 and 8392 ± 1103 for n–C 8 F 18. [Display omitted] • Infrared cross-sections for n–C 7 F 16 and n–C 8 F 18 measured from 300 to 350 K. • Cross-sections confirm literature values for the spectral peak at 1250 cm−1. • Radiative efficiency is 0.50 ± 0.06 and 0.54 ± 0.07 Wm−2ppbv−1 for n–C 7 F 16 and n–C 8 F 18. • 100-year global warming potential is 8738 ± 1149 for n–C 7 F 16 and 8392 ± 1103 for n–C 8 F 18. • Integrated cross-sections and climate metrics are temperature-independent over 300–350 K. [ABSTRACT FROM AUTHOR]

Absorption cross-sections of 2,2,3,3,3-pentafluoropropanol (PFPO) were derived from Fourier transform infrared spectra recorded from 565 to 3400 cm −1 with a resolution of 0.1 cm −1 over a temperature range of 298–362 K. These results were compared to previously published theoretical density functional theory (DFT) calculations and experimental measurements made at room temperature. We find good agreement between our experimentally derived results, DFT calculations, and previously published data. The only temperature dependence observed was in the centroid shift of the 850–1500 cm −1 band and in the amplitude of some of the absorption peaks. However, this temperature dependence does not result in a significant trend in integrated band strength as a function of temperature. We calculate an average integrated band strength of (1.991±0.001)×10 −16 cm molecule −1 for PFPO over the spectral range studied. Radiative efficiencies (REs) and the global warming potential (GWP) for PFPO were also derived. We find an average RE of 0.2603 ± 0.0007 W m − 2 ppbv − 1 and a GWP 100 of 19.8. The calculated radiative efficiencies show that no dependence on temperature and our findings are consistent with previous studies, increasing our confidence in the value of the GWP of PFPO. [ABSTRACT FROM AUTHOR]

We provide the results of human body absorption cross-section (ACS) measurements. The setup was based on the reverberation chamber as a well-known measurement environment capable of performing ACS measurements. The approach was supported by reference measurements on canonically shaped objects which were convenient for analytical (Mie scattering theory) ACS calculations. Measured ACS of canonical objects was in excellent agreement with calculated values. The ACS measurements of a human model were performed: 1) on an actual human body in an upright posture and 2) on a cylindrical water model made of vertically stacked water-filled jugs. The cylindrical model had the same water content as an average human body. Comparison between these two models showed a small difference in measured ACS within the measurement uncertainty of our setup. Thus, the cylindrical water model proved to be a useful artifact, especially for time-consuming broadband ACS measurements. [ABSTRACT FROM AUTHOR]

Cross-sections of perfluorotributylamine (PFTBA) were derived from Fourier transform spectroscopy at 570–3400 cm −1 with a resolution of 0.1 cm −1 over a temperature range of 298–344 K. These results were compared to theoretical density functional theory (DFT) calculations and to previous measurements of PFTBA made at room temperature. DFT calculations were performed using the B3LYP method and the 6-311G(d,p) basis set. We find good agreement between our experimentally derived results, DFT calculations, and previously published data. No significant temperature dependence in the PFTBA cross-sections was observed for the temperature range studied. We calculate an average integrated band strength of 7.81 × 10 −16 cm/molecule for PFTBA over the spectral range studied. Radiative efficiencies (RE) and global warming potentials (GWP) for PFTBA were also derived. The calculated radiative efficiencies show no dependence on temperature and agree with prior publications. We find an average RE of 0.77 Wm −2 ppbv −1 and a range of GWP from 6874 to 7571 depending on the lifetime used. Our findings are consistent with previous studies and increase our confidence in the value of the GWP of PFTBA. [ABSTRACT FROM AUTHOR]

Absorption by the contents of an equipment enclosure, particularly printed circuit boards (PCBs), affect the enclosure's shielding performance. At high frequencies, this absorption can be quantified using the angle of arrival and polarization averaged absorption cross-section (ACS). However, there is no available data on the high-frequency absorption characteristics of modern PCBs. In this study, we apply a reverberation chamber to the determination of the average ACS of a large number of PCBs taken from contemporary information and communication technology (ICT) equipment to provide a unique and comprehensive dataset. The ACS was found to range from 4 × 10−4–10−2 m2 from 2–20 GHz and different classes of PCB could be identified according to their surface characteristics. The “shadowing effect” of densely packed PCBs was also quantified for a subset of the PCBs. It was found that the ACS of a PCB in the stack was reduced by 20%–40% compared to its value when isolated. By way of a review of the general power balance analysis of an electrically large populated equipment enclosure in an external environment, we show how the acquired data will be useful for future qualification methodologies for ICT enclosures and PCBs. [ABSTRACT FROM PUBLISHER]

We analytically study the scalar perturbation of non-asymptotically flat (NAF) rotating linear dilaton black holes (RLDBHs) in 4-dimensions. We show that both radial and angular wave equations can be solved in terms of the hypergeometric functions. The exact greybody factor (GF), the absorption cross-section (ACS), and the decay rate (DR) for the massless scalar waves are computed for these black holes (BHs). The results obtained for ACS and DR are discussed through graphs. [ABSTRACT FROM AUTHOR]

Sm3+/Tm3+:NaGd(MoO 4) 2 crystals have been successfully grown by the vertical Bridgman method using spontaneous crystallization. The as-grown crystals presented dark-purple color, and the annealed crystal samples presented transparency with light yellow coloration. The crystal structure, the absorption, excitation and emission spectra, and the fluorescence decay curves were investigated. The absorption cross-section of Sm3+ 0.02 /Tm3+ y :NaGd(MoO 4) 2 (y = 0.01, 0.02, 0.05) at 405 nm, which is used as pumping channel for visible laser operation, are 8.87×10-20 cm2, 6.04×10-20 cm2 and 15.89×10-20 cm2, respectively. The emission cross-sections are 4.37×10-21 cm2, 6.63×10-21 cm2 and 3.83×10-20 cm2 for Sm3+ 0.02 /Tm3+ y :NaGd(MoO 4) 2 (y = 0.01, 0.02, 0.05) crystal at 645 nm. The fluorescence lifetimes of the 4G 5/2 multiplet at 645 nm under excitation at 405 nm are 0.44, 0.28 and 0.21 ms, respectively. The energy transfer efficiency of Sm3+ 0.02 /Tm3+ 0.01 :NaGd(MoO 4) 2 , Sm3+ 0.02 /Tm3+ 0.02 :NaGd(MoO 4) 2 and Sm3+ 0.02 /Tm3+ 0.05 : NaGd(MoO 4) 2 are 22.5%, 50% and 62.5%, respectively. • Sm3+/Tm3+:NaGd(MoO 4) 2 crystals have been grown using the Bridgman method. • The emission intensity at 645 nm decreases with the increase of Tm3+ concentration. • With the increase of Tm3+ concentration, the energy transfer efficiency is improved. • The possible energy transfer mechanism are discussed. [ABSTRACT FROM AUTHOR]

Solar distillation is an immensely promising, renewable energy-based solution route for potable water production from grey water. Noble plasmonic nanoparticles (e.g., Au, Ag) are typically employed in solar distillation systems for efficiency enhancement. However, their high cost renders such technologies economically nonviable. In this study, we evaluate the prospect of using Cu-coated Al as non-noble plasmonic nanoparticles for solar distillation based on the energy balance across various parts of a solar still (basin, glass cover and fluid). We compute the absorption and scattering cross-sections of these nanoparticles, and hence their optical activity. We show that particles of sizes <60 nm have greater absorption cross-section as compared to scattering cross-section in the ultraviolent (200 to 360 nm) and visible light spectrum (360 to 700 nm). The effects of nanoparticle concentration (0.004 % to 0.024 % of sizes 10–22 nm) in the nanofluid on the yield of distillate, energy efficiency and temperature of the fluid are analyzed. We report that Al-Cu nanoparticles enhance energy efficiency of a conventional solar still by as much as 64 % at a concentration of 0.012 %. The efficiency increases with increasing nanoparticle concentration and begins to saturate after 0.012 % concentration. • First study on use of Al-Cu non noble plasmonic nanoparticles for solar distillation • Beyond 60 nm particle size, (when radius ratio ~ 0.8), absorption efficiencies decrease. • Particles smaller than 25 nm show enhanced absorption as compared to scattering properties. • Efficiency enhances by 64 % with increase in volume concentration up to 0.012 % and thereafter saturates. • 14 nm sized nanoparticles at 0.012 vol% increase the temperature by 11 % as compared to conventional solar still. [ABSTRACT FROM AUTHOR]

We measure near-infrared absorption spectra of PbSe quantum dots (QDs) with three sizes (4.5, 5.0, and 5.6 nm) doped in UV gel with the concentration of 0.25–1.50 mg mL −1 by using an absorption-spectrum method. An empirical formula is proposed to describe the correlation of the first–second absorption-peak wavelengths and QD size. The peak-absorption cross-section is measured as 2.76–3.69×10 −16 cm 2 for 5.6-nm QD, and the absorption coefficient ranges in 0.19–0.59 cm −1 , both associated with the doping concentration and the QD size. Furthermore, the emission cross-sections are determined by measuring the photoluminescence spectra of QDs and using the McCumber relationship, which depend weakly on both the doping concentration and the QD size. For 5.6-nm QD, the measured peak-emission cross-section is 3.36–4.48×10 −16 cm 2 within the range of experimental doping concentration. [ABSTRACT FROM AUTHOR]

In this paper, we examine the spectrum of a massive scalar particle interacting with the strong gravitational field of a static, spherically symmetric object which is not quite massive enough to be a black hole. As was found in the case of massless particles, there exists a dense spectrum of long lived resonances (meta-stable states), which leads to an energy-averaged cross-section for particle capture which approaches the absorption cross-section for a Schwarzschild black hole. However, the generalization to nonzero mass introduces new phenomena, along with important qualitative changes to the scattering properties. In contrast to the massless case, there exists a spectrum of bound states with almost identical structure to that of the resonances, allowing for the possibility of radiative transitions and particle capture. The resonance lifetimes for elastic processes are parametrically larger than for massless particles, meaning the absorption cross-section approaches the black hole case faster than for massless scalars. [ABSTRACT FROM AUTHOR]

Mid-IR absorption cross-sections are measured for methane, ethane, ethylene and methanol over 2800–3400 cm −1 (2.9–3.6 μm) spectral region. Measurements are carried out using a Fourier-Transform-Infrared (FTIR) spectrometer with temperatures ranging 296–1100 K and pressures near atmospheric. As temperature increases, the peak cross-sections decrease but the wings of the bands increase as higher rotational lines appear. Integrated band intensity is also calculated over the measured spectral region and is found to be a very weak function of temperature. The absorption cross-sections of the relatively small fuels studied here show dependence on the bath gas. This effect is investigated by studying the variation of absorption cross-sections at 3.392 μm using a HeNe laser in mixtures of fuel and nitrogen, argon, or helium. Mixtures of fuel with He have the highest value of absorption cross-sections followed by Ar and N 2 . Molecules with narrow absorption lines, such as methane and methanol, show strong dependence on bath gas than molecules with relatively broader absorption features i.e. ethane and ethylene. [ABSTRACT FROM AUTHOR]

The generic non-extremal Kerr-Newman black holes are holographically dual to hidden conformal field theories in two different pictures. The two pictures can be merged together to the dual conformal field theories (CFTs) in general picture that are generated by $$SL(2,\mathbb {Z})$$ modular group. We find some extensions of the conformal symmetry generators that yield an extended local family of $$SL(2,\mathbb {R})_L \times SL(2,\mathbb {R})_R$$ hidden conformal symmetries for the Kerr-Newman black holes, parameterized by one deformation parameter. The family of deformed hidden conformal symmetry for Kerr-Newman black holes also provides a set of deformed hidden conformal symmetry for the charged Reissner-Nordstrom black holes. The set of deformed hidden conformal generators reduce to the hidden $$SL(2,\mathbb {R})$$ conformal generators for the Reissner-Nordstrom black hole for specific value of deformation parameter. We also find agreements between the macroscopic and microscopic entropy and absorption cross-section of scalars for the Kerr-Newman black hole by considering the appropriate temperatures and central charges for the deformed CFTs. [ABSTRACT FROM AUTHOR]

CFC-113a (CF3CCl3), CFC-112 (CFCl2CFCl2) and HCFC-133a (CF3CH2Cl) are three newly detected molecules in the atmosphere that are almost certainly emitted as a result of human activity. It is important to characterise the possible contribution of these gases to radiative forcing of climate change and also to provide information on the CO2-equivalence of their emissions. We report new laboratory measurements of absorption cross-sections of these three compounds at a resolution of 0.01 cm-1 for two temperatures 250 K and 295 K in the spectral range of 600-1730 cm-1. These spectra are then used to calculate the radiative efficiencies and global warming potentials (GWP). The radiative efficiencies are found to be between 0.15 and 0.3 W⋅m-2⋅ppbv-1. The GWP for a 100 year time horizon, relative to carbon dioxide, ranges from 340 for the relatively short-lived HCFC-133a to 3840 for the longer-lived CFC-112. At current (2012) concentrations, these gases make a trivial contribution to total radiative forcing; however, the concentrations of CFC-113a and HCFC-133a are continuing to increase. The 2012 CO2-equivalent emissions, using the GWP (100), are estimated to be about 4% of the current global CO2-equivalent emissions of HFC-134a. [ABSTRACT FROM AUTHOR]

The absorption cross-section of lanthanide ions is essential for the analysis of the lanthanide upconversion system. However, it is difficult to accurately obtain the ion absorption cross-section of luminescence powders. There are some factors that cannot be ignored, such as interface reflection, matrix scattering, and stimulated/spontaneous emission. Therefore, a modified two-flux radiative transfer model is established in our study under the consideration of the absorption, scattering, interface reflection, and stimulated/spontaneous emission effects for lanthanide-doped powder materials. Furthermore, the method to determine the ion absorption cross-section is proposed by measuring the directional-hemispherical reflectance, transmittance, and luminescence lifetime of a specified energy level. The single-doped powders of β-NaYF 4 : 20% Er3+ and β-NaYF 4 : 0.05% Er3+ synthesized through a high-temperature solid-state reaction method were selected as the experimental samples and characterized by XRD and SEM. The reflectance, transmittance, and emission spectra of slice samples in the wavelengths of 460 nm–1700 nm were measured. Moreover, the effects of different sample sintering degree, irradiation source powers, and interface conditions on the measured reflectance and the calculated absorption cross-section were investigated. The redshift of the spontaneous emission peaks (4I 13/2 and 4I 11/2 energy levels) of Er3+ ions in the measurements of reflectance spectra was observed and analyzed. The absorption cross-section of Er3+ ion, the scattering coefficient and interface reflectivities of NaYF 4 matrix were determined according to the established model and method. The applicability of the method was experimentally verified. This work provides references for accurate measurements of ion absorption cross-section of lanthanide upconversion luminescence system. • Two-flux model to determine absorption cross-section of lanthanide ions is established. • Scattering, interface reflection and emission effects are analyzed in spectral measurements. • The interface reflectivity is determined by luminescence lifetime measurements. • The scattering coefficient presents a strong wavelength dependence for powder samples. [ABSTRACT FROM AUTHOR]

In this work we have studied the scattering of scalar field around an extended black hole in F(R) gravity using WKB method. We have obtained the wave function in different regions such as near the horizon region, away from horizon and far away from horizon and the absorption cross-section are calculated. We find that the absorption cross-section is inversely proportional to the cube of Hawking temperature. We have also evaluated the Hawking temperature of the black hole via tunneling method. [ABSTRACT FROM AUTHOR]

Highlights: [•] In vivo estimation of the pigment absorption bands and the optical absorption cross-section, a ∗. [•] Four photosynthetic micro-organisms cultivated at two PAR levels were analyzed. [•] A new methodology was proposed: spectroradiometry measuring reflectances. [•] Some absorption bands were ubiquous, others were taxonomically specific and/or photo-physiological dependent. [•] A double peak feature at 671 and 683nm, supposed to be caused by PSII and PSI, was detected. [ABSTRACT FROM AUTHOR]

Abstract: Contradictory findings have been reported on the length dependence of optical absorption cross sections and fluorescence quantum yields in single-walled carbon nanotubes (SWCNTs). To clarify these points, studies have been made on bulk SWCNT dispersions subjected to length fractionation by electrophoretic separation or by ultrasonication-induced scission. Fractions ranged from ca. 120 to 760nm in mean length. Samples prepared by shear-assisted dispersion were subsequently shortened by ultrasonic processing. After accounting for processing-induced changes in the surfactant absorption background, SWCNT absorption was found constant within ±11% as average nanotube length changed by a factor of 3.8. This indicates that the absorption cross-section per carbon atom is not length dependent. By contrast, in length fractions prepared by both methods, the bulk fluorescence efficiency or average quantum yield increased with SWCNT average length and approached an apparent asymptotic limit near 1μm. This result is interpreted as reflecting the combined contributions of exciton quenching by sidewall defects and by the ends of shorter nanotubes. [Copyright &y& Elsevier]

Abstract: Erbium-doped germanotellurite glasses in the TeO2–GeO2–Nb2O5–K2O system have been prepared and their absorption and photoluminescence properties were investigated. Judd–Ofelt theory was applied to the different absorption intensities of the UV/vis Er3+ transitions, to determine the intensity parameters, Ω t (t=2, 4, 6), and to estimate the radiative lifetimes. However, for a single transition like the Er3+ emission to the ground state, at ca. 1.5μm, the absorption cross-section method is shown to be a simpler method to estimate the radiative lifetime of that particular transition. Experimental lifetimes were obtained from the photoluminescence decay curves of the 4I13/2 metastable state of Er3+ in different glasses and compared to the radiative lifetimes estimated by both methods. A better agreement was obtained by the absorption cross-section approach, yielding quantum efficiencies of 94% and 69% for 0.2mol% and 2mol% ErO1.5 doped samples, respectively. The up-conversion luminescence intensities of Er3+ ions in these glasses were also analyzed in the 400–900nm range and compared with up-conversion in samples co-doped with Ytterbium and/or Thulium. [Copyright &y& Elsevier]

We introduce an accurate and fast finite-difference time-domain (FDTD) method for calculating light absorption in nanoscale optical systems. The dispersive FDTD update equations were derived from auxiliary differential equations (ADE), wherein dispersive media were fitted by various dispersion models including the Drude, Debye, Lorentz, and critical point models. Light absorption in the dispersive media was quantified by calculating polarization pole currents in the ADE. To verify this simulation method, the absorption spectrum of a 300 nm thick silicon film was calculated and compared to an analytic solution. In addition, the absorption cross-section of a single silicon nanowire with a diameter of 300 nm was calculated using monochromatic and broadband light sources. We believe that this reformatted FDTD method is a powerful tool for the design of novel nanophotonic components, including nanowire photovoltaic devices. [ABSTRACT FROM AUTHOR]