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This study examined spectroscopic, thermal, and other qualities, such as the lasing parameters, of Sm3+-doped glass with the composition 40P2O5–30ZnO–20LiCl–10BaF2. The ellipsometric data were used in a Sellmeier dispersion relation to estimate the refractive index values of the glasses investigated. The measured absorption spectra of the doped glass reveal the presence of various absorption bands assigned to transitions from the 6H5/2 ground state attributed to Sm3+-ion-excited states. We studied the decay of the 4G5/2 level of the Sm3+ ions in the doped glass by analyzing its absorption and emission fluorescence spectra. The Judd–Ofelt hypothesis allowed us to determine that the quantum efficiency of the 4G5/2–6H7/2 transition is high: 96% and 97% for glass doped with 4.05 × 1019 ions/cm−3 and 11 × 1019 ions/cm−3, respectively. Furthermore, this glass exhibits efficient red/orange enhanced spontaneous emission that matches the excitation band of the photosensitizer material used in medical applications. [ABSTRACT FROM AUTHOR]

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]

The absorption cross-section of Cr2+ ions in a range of cubic Zn1–xMnxSe (x = 0–0.3) solid solutions was determined using nonlinear transmission measurements. The maximum absorption cross-section of about 1.04 × 10–18 cm2 was determined and shown to be practically independent of the Mn content (x) in the solid solution. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the influence of the surface quantum effect on the absorption cross section and the field enhancement factor of core-shell plasmonic nanoparticles. We apply a quantum approach based on surface response functions (SRF)—Feibelman d-parameters and mesoscopic boundary conditions. The discrete sources method is implemented, which makes it possible to perform an efficient numerical analysis of scattering problems accounting for surface quantum effect. The simulation results demonstrate a significant influence of the surface quantum effect on the optical characteristics of core-shell plasmonic nanoparticles. In particular, the surface quantum effect exhibits plasmon resonance damping up to 15 , and the blue shift in the spectral domain can reach 10 nm. [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]

Investigation on intrinsic properties of photosynthetic pigment molecules participating in solar energy absorption and excitation, especially their eigen-absorption cross-section (σik) and effective absorption cross-section (σ'ik), is important to understand photosynthesis. Here, we present the development and application of a new method to determine these parameters, based on a mechanistic model of the photosynthetic electron flow-light response. The analysis with our method of a series of previously collected chlorophyll a fluorescence data shows that the absorption cross-section of photosynthetic pigment molecules has different values of approximately 10-21 m², for several photosynthetic organisms grown under various conditions: (1) the conifer Abies alba Mill., grown under high light or low light; (2) Taxus baccata L., grown under fertilization or non-fertilization conditions; (3) Glycine max L. (Merr.), grown under a CO2 concentration of 400 or 600 µmol CO2 mol-1 in a leaf chamber under shaded conditions; (4) Zea mays L., at temperatures of 30°C or 35°C in a leaf chamber; (5) Osmanthus fragrans Loureiro, with shaded-leaf or sun-leaf; and (6) the cyanobacterium Microcystis aeruginosa FACHB905, grown under two different nitrogen supplies. Our results show that σik has the same order of magnitude (approximately 10-21 m²), and σ'ik for these species decreases with increasing light intensity, demonstrating the operation of a key regulatory mechanism to reduce solar absorption and avoid high light damage. Moreover, compared with other approaches, both σik and σ'ik can be more easily estimated by our method, even under various growth conditions (e.g., different light environment; different CO2, NO2, O2, and O3 concentrations; air temperatures; or water stress), regardless of the type of the sample (e.g., dilute or concentrated cell suspensions or leaves). Our results also show that CO2 concentration and temperature have little effect on σik values for G. max and Z. mays. Consequently, our approach provides a powerful tool to investigate light energy absorption of photosynthetic pigment molecules and gives us new information on how plants and cyanobacteria modify their light-harvesting properties under different stress conditions. [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]

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]

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 expression for absorption cross-section of massless as well as massive charged particles in the background of dilaton-axion black hole is determined in low and high frequency limits. The modification of the absorption cross-section in comparison to Reissner-Nordstrom black hole is discussed. [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]

The possibility of using heating of body tissue upon excitation of surface plasmons in two-layer spherical metal-graphene nanoparticles for thermal destruction of malignant neoplasms has been analyzed. Drude and Kubo models have been used to determine the frequency dependences of the dielectric function of the metal core and the conductivity of the graphene shell, respectively, and the distributions of temperatures in tumor tissue and surrounding healthy tissue have been determined by solutions of nonhomogeneous thermal conductivity equations. Values of thermophysical parameters of tumor tissue and healthy human tissue known from the literature have been used for numerical estimates and calculations. The evolution of the frequency dependences of the polarizability and absorption cross-sections of the indicated nanoparticles with the variation of the radius and material of the metal core and the thickness of the graphene shell has been studied. It has been shown that an increase in the radius of the metal core or thickness of the graphene shell results in an increase in the maximum values of the imaginary part of the polarizability and absorption cross-section, which is associated with increased interaction with the electromagnetic wave with increasing bulk metal content in the composite nanoparticle and with high concentration of free electrons in graphene layers. The possibility of spectral shifts of the polarizability maxima and the absorption cross-section with the variation of the core material of a two-layer nanoparticle, due to the essential difference in the values of the frequencies of bulk plasmons and the contribution of the ion core to the dielectric function, has been demonstrated. It has been established that the thermal conductivity is quasi-steady in the problem of heating of body tissue upon excitation of surface plasmon resonance in a composite nanoparticle. It has been proved that this method of cancer therapy is harmless to healthy tissue surrounding the tumor due to their extremely low heat. The results of numerical modeling demonstrate the need to use a conglomerate of metal-graphene nanoparticles in order to increase the effectiveness of therapy. [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]

Absorption of solar radiation by water vapor in the near‐UV region is a poorly understood but important issue in atmospheric science. To better understand water vapor near‐UV absorption, we constructed a cavity ring‐down spectrometer with bandwidth of 5 cm−1 (~0.05 nm) and obtained water vapor absorption cross sections at 1‐nm increments in the 290‐ to 350‐nm region. Water vapor displays structured absorption over this range with maximum and minimum cross sections of 8.4 × 10−25 and 1.6 × 10−25 cm2/molecule. Major water vapor absorption bands were observed at 293–295, 307–313, 319, 321–322, and 325 nm, with cross‐section values higher than 4.0 × 10−25 cm2/molecule. To obtain further insight into major water vapor absorption bands, we measured water vapor absorption cross sections at 0.05‐nm intervals in the 292‐ to 296‐nm, 306‐ to 314‐nm, and 317‐ to 326‐nm region. Field UV residual spectra not only exhibited increased attenuation at higher atmospheric water vapor loadings but also showed structures suggested by the laboratory water vapor absorption spectrum. Spaceborne UV radiance spectra have spectral structures resembling the differential cross‐section spectrum constructed from the laboratory wavelength‐dependent water vapor absorption cross sections presented here. Incorporating water vapor absorption cross‐section data into a radiative transfer model yielded an estimated energy budget of 0.26 W/m2 for the standard U.S. atmosphere and 0.76 W/m2 for the tropics. This shows that water vapor near‐UV absorption is an important contributor for climate simulation and ozone retrievals. Plain Language Summary: Water vapor near‐UV absorption is an overlooked subject of core importance to atmospheric science. We constructed a cavity ring‐down spectrometer with a bandwidth comparable to those of field UV spectrometers and determined water vapor absorption cross sections at 1‐nm intervals in the 290‐ to 350‐nm region. We also measured water vapor absorption cross sections at 0.05‐nm intervals surrounding major absorption bands. We provide field evidence to support laboratory water vapor near‐UV absorption measurements and present comparisons of the estimated optical depth spectra of ozone with those of water vapor for the standard U.S. and tropical atmospheres. Our findings suggest that water vapor near‐UV absorption will significantly affect ozone retrieval from UV measurements, particularly in the tropical region. Incorporating cross‐section data into a radiative transfer model, we estimated that the energy budget of water vapor near‐UV absorption was about 0.26 W/m2 for the standard U.S. atmosphere and 0.76 W/m2 for the tropics. Since it was not thought that water vapor could have near‐UV absorption, the effect of such absorption is not currently included in radiation and climate simulation models. Our work on water vapor near‐UV absorption is expected to change the paradigm in atmospheric measurements from UV remote sensing observations and how atmospheric radiation and climate are modeled. Key Points: Water vapor displays structured absorption bands over the 290‐ to 350‐nm range, with cross sections in the range of 10−24 to 10−25 cm2/moleculeField evidence for water vapor near‐UV absorption is presentedWater vapor near‐UV absorption affects O3 retrieval and modeling of atmospheric radiation and climate [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]

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]

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]

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 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]

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]

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]

In this paper we study the effects of black hole mass on the absorption cross-section for a massive scalar field propagating in a five-dimensional topological Chern-Simons black hole at the low-frequency limit. We consider the two branches of black hole solutions (α = ±1) and we show that, if the mass of black hole increase the absorption cross-section decreases at the zero-frequency limit for the branch α = -1 and for the other branch, α = 1, the behavior is opposite, if the black hole mass increase the absorption cross-section increases. Also we find that beyond a certain frequency value, the mass black hole does not affect the absorption cross-section. [ABSTRACT FROM AUTHOR]

CdSeS/ZnS quantum dots (QDs) were synthesized through the chemical route. The optical limiting behavior of these QDs was observed. The quantum dots' nonlinear absorption and nonlinear refraction were investigated by the Z-scan technique using a Nd:YAG laser second-harmonic radiation (λ = 532 nm, t = 35 ps). Based on the absorption and fluorescence spectra, it is reasonable for us to infer that the nonlinear absorption arises from free carrier absorption (FCA). These QDs have average absorption cross-section of 1.26 × 10-16cm2 and nonlinear refractive index in the order of 10-8esu. The large nonlinear absorption perhaps allows them to be candidate material for the optical limiting devices. [ABSTRACT FROM AUTHOR]

The NO2 density error retrieved by the traditional method of differential optical absorption spectroscopy (DOAS) was analyzed. The technique for reducing the error is proposed and used to obtain the NO2 density of Chengdu through DOAS. [ABSTRACT FROM AUTHOR]

The behavior of a Dirac field in a Schwarzschild black hole spacetime is studied. In this work the Hawking temperature and the absorption cross-section for Schwarzschild black hole placed in Dirac field are calculated, taking into consideration the matter waves reflected from the event horizon. The absorption cross-section σabs in Dirac field is found to be ⅛ of absorption cross-section in scalar field. The emission spectra of Schwarzschild black hole placed in an environment of Dirac field is also obtained. [ABSTRACT FROM AUTHOR]

The nature of scalar wave functions near the horizon of Reissner–Nordstrom (RN) extremal and Schwarzschild–de Sitter (SdS) extremal black holes are found using WKB approximation and the effect of reflection of waves from the horizon. The absorption cross-section σabs when RN extremal and SdS extremal black holes placed in a Klein–Gordon field is calculated. [ABSTRACT FROM AUTHOR]

The photoabsorption cross-sections of sulfur dioxide were measured in the spectral regions of 200–230 nm and 275–315 nm at 298–415 K, using a grating monochromator with a resolution of 0.2 nm. The discrete absorption cross-section is directly correlated with the number of quantum excited from the base state. The absorption cross-sections at the peaks of discrete bands decreased linearly with the increase of temperature, which corresponded to the decrease in the population of vibrational and rotational transitions from the base level to higher excitation levels. The absorption cross-section peaks decreased linearly when the temperature increased from 298 to 415 K, with relative drops of 74.0% and 75.8% at 200–230 nm and 275–315 nm, respectively. Another distinctive feature of sulfur dioxide absorption spectra in the above two spectral regions was the quasiperiodic structure of the absorption peaks, whose equal wavelength intervals were 1.53 nm and 1.95 nm, respectively. Red and blue shifts were not found at the absorption peak positions. [ABSTRACT FROM AUTHOR]

Oxygen is not only important which people rely on but also one type of important industrial gas. Considering that there are some disadvantages of traditional methods to measure the oxygen concentration, the tunable diode laser absorption spectroscopy is researched in this paper combined with the phase-lock amplify technique. This method combines the high power, good monochrome, wavelength tuned with the drive current or temperature of laser and the advantage of phase-lock amplifier to improve the signal and noise ratio and the measure precision. Based on designing the detect system, the quantitative relation between the oxygen absorption cross-section and temperature at 760.26 nm is deduced. Moreover the linear bias of the detect result is 1%, and there is no interference caused by the other components mixed in the measured gas. So it can be seen that this technology has many advantages and can meet the application of industry very well. [ABSTRACT FROM AUTHOR]

The Hawking temperature corresponding to the black hole horizon of Schwarzschild–de Sitter (SdS) black hole was found using WKB approximation and the effect of reflection of waves from the quantum horizon. The absorption cross-section σabs when SdS black hole is placed in a Klein-Gordon field is calculated and is found to be inversely proportional to the Hawking temperature. [ABSTRACT FROM AUTHOR]

The photodissociation dynamics of the triatomic (or pseudo‐triatomic) system in the nonadiabatic multiple electronic states is investigated by employing a time‐dependent quantum wave packet method, while the time propagation of the wave packet is carried out using the split‐operator scheme. As a numerical example, the photodissociation dynamics of CH3I in three electronic states 1Q1(A′), 1Q1(A″), and 3Q0+ is studied and CH3I is treated as a pseudotriatomic model. The absorption spectra and product vibrational state distributions are calculated and compared with previous theoretical work. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2005 [ABSTRACT FROM AUTHOR]

Absorption spectroscopy, which is widely used for concentration measurements of tropospheric and stratospheric compounds, requires precise values of the absorption cross-sections of the measured species. NO2, O2 and its collision-induced absorption spectrum, and H2O absorption cross-sections have been measured at temperature and pressure conditions prevailing in the Earth’s atmosphere. Corrections to the generally accepted analysis procedures used to resolve the convolution problem are also proposed. [ABSTRACT FROM AUTHOR]

Under conditions of iron-stress, the Photosystem II associated chlorophyll a protein complex designated CP 43′, which is encoded by the isiA gene, becomes the major pigment-protein complex in Synechococcus sp. PCC 7942. The isiB gene, which is located immediately downstream of isiA, encodes the protein flavodoxin, which can functionally replace ferredoxin under conditions of iron stress. We have constructed two cyanobacterial insertion mutants which are lacking (i) the CP 43′ apoprotein (designated isiA) and (ii) flavodoxin (designated isiB). The function of CP 43′ was studied by comparing the cell characteristics, PS II functional absorption cross-sections and Chl a fluorescence parameters from the wild-type, isiA and isiB strains grown under iron-stressed conditions. In all strains grown under iron deprivation, the cell number doubling time was maintained despite marked changes in pigment composition and other cell characteristics. This indicates that iron-starved cells remained viable and that their altered phenotype suggests an adequate acclimation to low iron even in absence of CP 43′ and/or flavodoxin. Under both iron conditions, no differences were detected between the three strains in the functional absorption crossection of PS II determined from single turnover flash saturation curves of Chl a fluorescence. This demonstrates that CP 43′ is not part of the functional light-harvesting antenna for PS II. In the wild-type and the isiB strain grown under iron-deficient conditions, CP 43′ was present in the thylakoid membrane as an uncoupled Chl-protein complex. This was indicated by (1) an increase of the yield of prompt Chl a fluorescence (F) and (2) the persistence after PS II trap closure of a fast fluorescence decay component showing a maximum at 685 nm. [ABSTRACT FROM AUTHOR]

The size of the Photosystem II light harvesting antenna and the absorption cross-sections of PS I (σ) and PS II (σ) were examined in relation to photosynthetic performance fluorescence. Wild-type (WT) rye ( Secale cereale) and barley ( Hordeurn vulgare) as well as the barley chlorophyll b-less chlorina F2 mutant were grown under control and intermittent light (IML) conditions. (σ) in control barley F2 was similar to IML grown WT rye and barley, which, in turn was 2.5 to 3.5 times smaller than for control WT plants. In contrast, σ was similar for all control plants. This was 2.5 to 4 times larger than for IML-grown WT plants. IML-grown barley mutant plants had the smallest absorption cross-sections. Photosynthetic light response curves revealed that the barley chlorina F2-mutant had rates of oxygen evolution on a per leaf area basis that were only slightly lower than control WT rye and barley while IML-grown plants had strongly reduced photosynthetic performance. Convexity (Θ) for control barley chlorina F2-mutants was equal to the WT controls (0.6-0.7), while all IML-grown plants had a Θ of 0. This indicates that, in contrast to control barley mutants, IML-plants were limited by PS II turn-over rates at all irradiances. However, on a per leaf Chl-basis the IML-grown plants exhibited the highest photosynthetic rates. Thus, the comparatively poor photosynthetic rates for IML-grown plants on a per leaf area basis were not due to less efficient photosynthetic reaction centers, but may rather be due to an increased limitation from PS II turn-over and a reduction in the number of reaction centers per leaf area. [ABSTRACT FROM AUTHOR]

The effects of nitrate, phosphate, and iron starvation and resupply on photosynthetic pigments, selected photosynthetic proteins, and photosystem II (PSII) photochemistry were examined in the diatom Phaeodactylum tricornutum Bohlin (CCMP 1327). Although cell chlorophyll a (chl a ) content decreased in nutrient-starved cells, the ratios of light-harvesting accessory pigments (chl c and fucoxanthin) to chl a were unaffected by nutrient starvation. The chl a-specific light absorption coefficient (a*) and the functional absorption cross-section of PSII (σ) increased during nutrient starvation, consistent with reduction of intracellular self-shading (i.e. a reduction of the "package effect") as cells became chlorotic. The light-harvesting complex proteins remained a constant proportion of total cell protein during nutrient starvation, indicating that chlorosis mirrored a general reduction in cell protein content. The ratio of the xanthophyll cycle pigments diatoxanthin and diadinoxanthin to chl a increased during nutrient starvation. These pigments are thought to play a photoprotective role by increasing dissipation of excitation energy in the pigment bed upstream from the reaction centers. Despite the increase in diatoxanthin and diadinoxanthin, the efficiency of PSII photochemistry, as measured by the ratio of variable to maximum fluorescence (F[SUBv]/F[SUBm]) of dark-adapted cells, declined markedly under nitrate and iron starvation and moderately under phosphate starvation. Parallel to changes in F[SUBv]/F[SUBm] Were decreases in abundance of the reaction center protein D1 consistent with damage of PSII reaction centers in nutrient-starved cells. The relative abundance of the carboxylating enzyme, ribulose bisphosphate carboxylase/oxygenase (RUBISCO), decreased in response to nitrate and iron starvation but not phosphate starvation. Most marked was the decline in the abundance of the small subunit of RUBISCO in nitrate-starved cells. The changes in pigment content and fluorescence characteristics were typically reversed within 24 h of resupply of the limiting nutrient. [ABSTRACT FROM AUTHOR]

The effect of steady-state nitrogen limitation on photosynthetic characteristics and growth efficiency was examined in the marine hoptohyte Isochrysis galbana Green. Nitrate limited chemostats were maintained at nine dilution rates, ranging from 0.18-0.96 d[SUP-1], under continuous irradiance levels of 175 μmole quanta m[SUP-2] s[SUP-1], an irradiance level which saturated photosynthesis at all growth rates. Nitrogen limitation led to an overall reduction in pigmentation and a decrease in the cellular concentration of reaction centers; however, the optical absorption cross section, normalized to Chl a, increased. Moreover, Chl c/a ratios were higher in nitrogen-limited cells; the change in Chl c/a ratios were correlated with an increase in the functional size of Photosystem II. Both light saturated photosynthetic rates normalized per cell and specific respiratory losses were positively linearly correlated with growth rate. Light saturates photosynthetic rates normalized to Chl a remained relatively insensitive to the rate of nitrogen supply the minimum quantum requirement for gross photosynthetic oxygen evolution increased from 12.4 to 17.0 quanta / O[SUB2] At the growth irradiance, the quantum requirement increased 88% from 19.9 to 37.5 quata / O[SUB2] photosynthesis, / respiration ratios remained relatively constant at dilution rates greater than 35% of the maximum relative growth rate. Consequently, net growth efficiency, defined as the ratio of the specific growth rate, μ, to specific gross photosynthesis, p. also remained relatively constant over this range of growth rates overaging 85 ± 3%. [ABSTRACT FROM AUTHOR]

A detailed quantitative study was conducted on state 1-state 2 transition and its reversal in broken chloroplasts by modulated fluorimetry. The characteristics of the transition obtained supported other previous in-vitro findings. More importantly, a very close quantitative similarity was obtained under suitable conditions to previous in-vivo studies, particularly in approaching a constancy of F/F during the transition and the equality of the fractional change of these fluorescence parameters with the calculated light distribution fraction to PS II. This confirms that in broken chloroplasts too, the state transitions involve reciprocal changes in the absorption cross-sections of PS II and PS I. [ABSTRACT FROM AUTHOR]

A procedure is described which permits determination of the absolute absorption cross-section of a photosynthetic unit from the kinetics of reaction center photo-oxidation under weak, continuous actinic illumination. The method was first tested on a simple model compound of known absorption cross-section. We then applied the technique to absorption cross-section and functional antenna size measurements in photosystem I (PS I). A kinetic model is presented that can be used to fit P700 photo-oxidation measurements and extract the effective photochemical rate constant. The procedure is shown to properly correct for sample scattering and for the presence of heterogeneous absorbers (pigments not functionally coupled to P700). The relevance of these corrections to comparisons of antenna size using techniques that measure 'relative' absorption cross-sections is discussed. Measurements on pea thylakoids in the presence and absence of 5 mM MgCl show a 45% increase in PS I absorption cross-section in unstacked thylakoids. Analysis of detergent-isolated 'native' PS I preparations (200 chlorophyll a+b/P700) clearly indicate that the preparation contains a broad distribution of antenna sizes. Finally, we confirm that Chlamydomonas reinhardtii strain LM3-A4d contains a PS I core antenna complex which binds only ∼60 chlorophyll a/P700, about half the functional size of the wild type complex. Limitations associated with calculation of functional antenna size from cross-section measurements are also discussed. [ABSTRACT FROM AUTHOR]

The photoinduced charge transfer process of a D-π-A molecule (W1) and three D-D-π-A molecules (WS5–WS7) with triphenylamine as a donor was studied theoretically. D-D-π-A molecules are formed by inserting donors between the triphenylamine and π-linker (π-bridge) on the base of the W1 molecule. The results showed that donor insertion resulted in a red shift in the absorption spectrum, and the absorption intensity increased to a certain extent. A visualization method was used to observe the charge transfer of the four molecules in the process of one- and two-photon absorption (TPA). The local excitation enhanced charge transfer excitation in the TPA process was analyzed and discussed, and the insertion of the thiazolo[5,4-d]thiazole donor showed the largest TPA cross-section. This work contributed to the profound understanding of D-D-π-A molecules and the design of large cross-section TPA molecules. [ABSTRACT FROM AUTHOR]

The optical diffraction radiation that accompanies the motion of a modulated beam of electrons near a dielectric and silver nanowire scatterers is investigated in the two-dimensional formulation. Our goal is to compute the field in the near and far zones and analyze how it depends on electron beam parameters. We demonstrate the excitation of internal resonances of such a scatterer that can be useful in the design of nanoscale non-invasive beam position monitors. [ABSTRACT FROM AUTHOR]

Abstract: The kinetic parameters of an important atmospheric reaction, CH3O2+NO2+M→CH3O2NO2+M, have been recorded by monitoring directly the changes in concentrations of methylperoxy radicals (CH3O2) in the gas phase employing a new mid-infrared quantum cascade laser (QCL)-based apparatus. CH3O2 radicals in our apparatus have been generated by pulsed UV laser (266 nm) photolysis of CH3I in a gaseous mixture with oxygen. The absorption band corresponding to the mid-infrared O-O stretching fundamental of the peroxy radical, within a narrow spectral range, 1070-1120 cm-1, has been recorded by tuning the wavelength of the QCL operated in CW mode. The kinetics of the aforementioned reaction of CH3O2 with NO2 has been followed by analyzing the changes of the infrared (QCL) decay profile of CH3O2 at 9.1μm(1098.9cm-1) maintaining a pseudo first order reaction condition. We noticed that the rate constant of the reaction at 298 K varies in the range of (1.21-3.08) ×10-12cm3molecule-1s-1 for changing the total pressure in the range of 75-730 mbar. The absorption cross-section of CH3O2 at the probe wavelength (1098.9cm-1), has been estimated for the first time to be 8.3±0.4×10-20cm2.Graphical Abstract : Kinetics measurement of an atmospherically important gas phase reaction, CH3O2+NO2+M→CH3O2NO2+M, is studied using a newly developed apparatus based on pulsed UV laser photolysis time-resolved mid-infrared absorption spectroscopy. CH3O2 radicals are probed in the mid-infrared by a CW quantum cascade laser (QCL). [ABSTRACT FROM AUTHOR]