Journal articles: 'Emission and transmission spectrum'

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Lu, Lewei. "Observation and feature measurements of cloud and haze in exoplanet atmosphere based on transmission spectra." Highlights in Science, Engineering and Technology 38 (March 16, 2023): 90–96. http://dx.doi.org/10.54097/hset.v38i.5738.

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Clouds and hazes are important components of exoplanet atmospheres. This paper generalizes features and applications of exoplanet clouds and hazes in transmission spectra. A transmission spectrum presents a planet atmosphere’s wavelength-dependent absorption ability of host star’s radiation during transit. Effective transit radius model is often adopted to explain the wavelength-dependent absorption. In spectrum processing, the effect of stellar limb darkening and star spots should be taken into consideration. Clouds and hazes change features of planet transmission spectrums considerably, e.g., clouds reduce or eliminate absorption features on all bands observed. Since hazes (with small sizes) produce Rayleigh scattering, their reduction in absorption depth is greater in optical band than in infrared band. As transmission spectrum provides limited data about exoplanet atmospheres, emission and reflection spectrum during secondary transit should receive more observation. JWST will perform well in all forms of atmospheric spectrum observation. Advanced knowledge about clouds and hazes will benefit the confine of exoplanet atmospheres’ chemical composition, biosignatures, meteorology as well as planet evolvement model. These results shed light on guiding further exploration of exoplanets and life possibilities on them.

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Wang, Zhijian, Haiming Zhang, Zhijun Wang, et al. "Structure and strong ultraviolet emission characteristics of amorphous ZnO films grown by electrophoretic deposition." Journal of Materials Research 18, no. 1 (2003): 151–55. http://dx.doi.org/10.1557/jmr.2003.0021.

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Structure and ultraviolet emission characteristics of amorphous ZnO films grown on indium tin oxide coated glass substrates by electrophoretic deposition were investigated using Raman spectra and photoluminescence. The Raman spectrum shows a unique resonant multiphonon process within amorphous ZnO films. The photoluminescence spectrum of amorphous ZnO films shows a strong ultraviolet emission while the visible emission is nearly fully quenched. The transmission electron microscopy, x-ray diffraction, x-ray photoelectron spectrum, and infrared spectrum are used to detect the structure of amorphous ZnO powder. The complex water plays an important role in the photoluminescence intensity emission.

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Kappelmeier, John A., Ryan J. MacDonald, and Nikole K. Lewis. "From the Shadows: The Impact of Nightside Thermal Emission on Ultrahot Jupiter Transmission Spectrum Retrievals." Astrophysical Journal 975, no. 1 (2024): 61. http://dx.doi.org/10.3847/1538-4357/ad6f9d.

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Abstract Transmission spectroscopy is the most widely used technique for studying exoplanet atmospheres. Since the planetary nightside faces the observer during a transit, highly irradiated giant exoplanets with warm nightsides emit thermal radiation that can contaminate transmission spectra. Observations of ultrahot Jupiters in the near- and mid-infrared with JWST are especially susceptible to nightside contamination. However, nightside thermal emission is generally not considered in atmospheric retrievals of exoplanet transmission spectra. Here, we quantify the potential biases from neglecting nightside thermal emission in multidimensional atmospheric retrievals of an ultrahot Jupiter. Using simulated JWST transmission spectra of the ultrahot Jupiter WASP-33b (0.8–12 μm), we find that transmission spectrum retrievals without nightside emission can overestimate molecular abundances by almost an order of magnitude and underestimate the dayside temperature by ≳400 K. We show that a modified retrieval prescription, including both transmitted light and nightside thermal emission, correctly recovers the atmospheric properties and is favored by Bayesian model comparisons. Nightside thermal contamination can be readily implemented in retrieval models via a first-order approximation, and we provide formulae to estimate whether this effect is likely to be significant for a given planet. We recommend that nightside emission should be included as standard practice when interpreting ultrahot Jupiter transmission spectra with JWST.

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Pell, Randy J., Charles E. Miller, Bruce R. Kowalski, and James B. Callis. "Infrared Emission Spectroscopy with Transient Cooling." Applied Spectroscopy 47, no. 12 (1993): 2064–71. http://dx.doi.org/10.1366/0003702934066235.

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A new approach for collection of infrared spectral data from optically opaque materials is explored. This approach has previously been introduced in the literature and is known as transient infrared transmission spectroscopy (TIRTS). The front surface of a hot sample is transiently cooled with a jet of cold gas, and the ratio of the spectrum measured after cooling to that measured before cooling is shown to closely resemble a transmission spectrum. This report provides for a more theoretical understanding of the experiments than provided by previous workers, making use of unsteady-state heat flow calculations, harmonic oscillator modeling, and radiation transfer theory. Experimental data are collected from a solid polymer sample and two viscous liquid samples. The position of the spectral features for the emission measurements corresponds with transmission measurements, with some saturation of the more intense spectral features noted. Faster scanning instrumentation, proper pulse scan synchronization, or rotation of solid samples, as demonstrated by previous workers, may resolve the saturation problem.

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Kaplan, M. S., D. R. Haynor, R. S. Miyaoka, T. K. Lewellen, and R. L. Harrison. "Simultaneous transmission/emission imaging for SPECT using energy spectrum fitting." IEEE Transactions on Nuclear Science 42, no. 4 (1995): 1196–200. http://dx.doi.org/10.1109/23.467850.

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Goyal, Jayesh M., Nathan Mayne, Benjamin Drummond, et al. "A library of self-consistent simulated exoplanet atmospheres." Monthly Notices of the Royal Astronomical Society 498, no. 4 (2020): 4680–704. http://dx.doi.org/10.1093/mnras/staa2300.

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ABSTRACT We present a publicly available library of model atmospheres with radiative-convective equilibrium pressure–temperature (P-T) profiles fully consistent with equilibrium chemical abundances, and the corresponding emission and transmission spectrum with R ∼ 5000 at 0.2 µm decreasing to R ∼ 35 at 30 µm, for 89 hot Jupiter exoplanets, for four recirculation factors, six metallicities, and six C/O ratios. We find the choice of condensation process (local/rainout) alters the P-T profile and thereby the spectrum substantially, potentially detectable by James Webb Space Telescope. We find H− opacity can contribute to form a strong temperature inversion in ultrahot Jupiters for C/O ratios ≥ 1 and can make transmission spectra features flat in the optical, alongside altering the entire emission spectra. We highlight how adopting different model choices such as thermal ionization, opacities, line-wing profiles and the methodology of varying the C/O ratio, effects the P-T structure, and the spectrum. We show the role of Fe opacity to form primary/secondary inversion in the atmosphere. We use WASP-17b and WASP-121b as test cases to demonstrate the effect of grid parameters across their full range, while highlighting some important findings, concerning the overall atmospheric structure, chemical transition regimes, and their observables. Finally, we apply this library to the current transmission and emission spectra observations of WASP-121b, which shows H2O and tentative evidence for VO at the limb, and H2O emission feature indicative of inversion on the dayside, with very low energy redistribution, thereby demonstrating the applicability of library for planning and interpreting observations of transmission and emission spectrum.

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De Cesare, Pablo Nicolas. "Characterization of the ISDB-Tb critical spectrum mask." ACTA IMEKO 1, no. 1 (2012): 42. http://dx.doi.org/10.21014/acta_imeko.v1i1.19.

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Non-linearity in the ISDB-T transmission chain causes intermodulation products that widens the spectrum emission and should be taken into account when assigning frequency channels. The characterization of the transmission spectrum mask is one of the most important measurements in order to achieve the best use of the electromagnetic spectrum. The use of critical mask defined in [1] allows allocations of co-site adjacent channels for an efficient use of the electromagnetic spectrum that is a finite and limited resource. This paper discusses different test procedures using spectrum analyzers and dedicated digital TV analyzers in order to measure the ISDB-T transmission mask.

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Solomon, Peter R., Robert M. Carangelo, David G. Hamblen, and Philip E. Best. "Infrared Analysis of Particulates by FT-IR Emission/Transmission Spectroscopy." Applied Spectroscopy 40, no. 6 (1986): 746–59. http://dx.doi.org/10.1366/0003702864508421.

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In this paper we report on a new method for the on-line chemical characterization of gas-suspended particulate and liquid droplet streams. The method is a combination of emission and transmission (E/T) spectroscopy performed using a Fourier transform infrared (FT-IR) spectrometer and a cell which allows analysis of room-temperature particulates surrounded by hot walls. The method was based on the discovery that the spectrum of radiation coming from such particles contained structure corresponding to the infrared absorption spectrum of the particulates. It was determined that the observed energy was wall radiation which reaches the detector after refraction by, and transmission through the particles. The shape of the observed spectrum relative to that of the wall spectrum is reduced at the absorption bands of the particulates. The general concepts of the E/T method were validated by samples with sizes varying from a few to several hundred microns with varying optical properties. For solids, excellent results were achieved for composition measurements. For a sample of known particle size, quantitative absorbance spectra were obtained from the E/T spectra with the use of a model based on ray optics. The spectra were in good quantitative agreement with absorbance spectra derived by the KBr pellet method for the same sample thickness. The E/T derived spectra were somewhat noisier than the KBr pellet spectra, but were free of Christiansen effect band distortions and scattering contributions. The E/T method has the additional advantage of requiring little or no sample preparation.

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Ridden-Harper, Andrew, Ernst de Mooij, Ray Jayawardhana, Neale Gibson, Raine Karjalainen, and Marie Karjalainen. "High-resolution Emission Spectroscopy of the Ultrahot Jupiter KELT-9b: Little Variation in Day- and Nightside Emission Line Contrasts." Astronomical Journal 165, no. 5 (2023): 211. http://dx.doi.org/10.3847/1538-3881/acc654.

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Abstract The transmission spectrum of the ultrahot Jupiter KELT-9b (T eq ∼ 4000 K) exhibits absorption by several metal species. We searched for atomic and molecular lines in its emission spectrum by observing partial phase curves with the Calar Alto high-Resolution search for M dwarfs with Exoearths with Near-infrared and optical Echelle Spectrographs (R ∼ 80,000–95,000). We find evidence for emission by Si i in the atmosphere of KELT-9b for the first time. Additionally we find evidence for emission by Mg i and Ca ii, which were previously detected in transmission, and confirmed earlier detections of Fe i emission. Conversely, we find no evidence for dayside emission from Al i, Ca i, Cr i, FeH, Fe ii, K i, Li i, Mg ii, Na i, OH, Ti i, TiO, V i, V ii, VO, and Y i. By employing likelihood mapping, we find indications of there being little variation in emission line contrast between the day- and nightsides—suggesting that KELT-9b may harbor iron emission on its nightside. Our results demonstrate that high-resolution ground-based emission spectroscopy can provide valuable insights into exoplanet atmospheres.

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SONG, KAI, RENAUD VALLEE, MARK VAN DER AUWERAER, and KOEN CLAYS. "SPONTANEOUS EMISSION OF NANO-ENGINEERED FLUOROPHORES IN PHOTONIC CRYSTALS." Journal of Nonlinear Optical Physics & Materials 15, no. 01 (2006): 1–8. http://dx.doi.org/10.1142/s0218863506003128.

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The spontaneous emission of fluorophores embedded in a photonic crystal has been studied. By nano-engineering a sandwich-like photonic structure, such that fluorophore-coated photonic atoms constitute a middle layer between the photonic crystals, we have been able to precisely control the location of fluorophores in photonic crystals and exclude the presence of fluorophores at the surface of the crystal. It has been found that the stopband in the transmission spectrum is deeper than the stopband in the emission spectrum. We conjecture that the omnidirectional propagation of the emission from a point source in an incomplete photonic bandgap is the cause of the shallower stopband in emission.

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Pan, Jingzhi, and Ruiqi Yuan. "Optimization of the Peak Power of the Output Spectrum of Spontaneous Emission Spectrum Amplified by O-Band Fiber." Highlights in Science, Engineering and Technology 72 (December 15, 2023): 976–83. http://dx.doi.org/10.54097/xzpgw472.

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As the demand for information and communication continues to increase, the optimization and improvement of optical fiber communication has been a key focus of scientific research, with profound impacts on multiple fields, including military, aerospace, industrial, and daily communications. Based on the in-depth understanding and establishment of the rate equation and power propagation equation of each energy level system, this study explores the influence of fiber length and doping concentration on amplifying spontaneous emission spectrum under certain pump power. With a comprehensive understanding of its characteristics, analog annealing algorithms are employed to optimize the length and doping concentration of the fiber to maximize the peak power of the output spectrum. This research provides an important contribution to the further development and efficiency improvement of optical fiber communication in the future. It is concluded that for the O-band, the output peak of high power can provide greater signal strength, thereby increasing the transmission distance and bandwidth capacity of the signal. This is essential for applications such as long-distance communications, high-speed data transmission, and multi-channel transmission.

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Makarenko, F., A. Arsent'ev, and Konstantin Zolnikov. "NARROWING OF THE GAAS LED EMISSION SPECTRUM DUE TO THE USE OF THE INP (AG) LIGHT FILTER." Modeling of systems and processes 13, no. 4 (2021): 32–38. http://dx.doi.org/10.12737/2219-0767-2021-13-4-32-38.

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АЛ115В LED emission spectrum at currents of 6.3 mA and 56 mA, as well as the emission spectrum using an InP (Ag) light filter at current 56 mA, are studied. A classical approximation of the spontaneous emission spectrum of a straight-band LED is presented (without taking into account the narrowing of the band gap due to the high degree of LED doping). The analytical and experimental widths of the LED band gap are estimated. The transmission spectrum of an InP (Ag) light filter is presented, taking into account reflection losses in the region of fundamental transitions. The spectral dependence (fragment) of the InP absorption coefficient is determined. The error is estimated. It is proposed to use АЛ115В with an InP (Ag) light filter in order to narrow the spectral band of radiation from 53 nm to 34 nm.

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Dao, Tuan Anh, Quang Nhat Nguyen, Loan Nguyen Phuong Vuong, and Hung Vu Tuan Le. "Study on influences of Sb doping content on the defects of ZnO film by photoluminescence (PL) spectrum and raman scattering spectrum." Science and Technology Development Journal 18, no. 3 (2015): 78–84. http://dx.doi.org/10.32508/stdj.v18i3.823.

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Sb-doped ZnO thin films with different values of Sb concentrations are deposited on glass substrate by using spin-coating technique. The influences of Sb doping content on the microstructural, photoluminescence and Raman properties of ZnO film are systematically investigated by X-ray diffraction (XRD), transmission spectrum, photoluminescence (PL) spectrum and Raman scattering spectrum. The results indicate that ZnO thin film doped with Sb exhibits a hexagonal wurtzite structure with preferred c-axis orientation. The strong violet emission peak located at 3.11 eV is observed in the Sb-doped ZnO thin film by photoluminescence. Conbining the Raman scattering spectrum with photoluminescence, it is concluded that the strong violet emission peak related to SbZn-O complex defect in ZnO:Sb film.

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Silkis, E. G., E. G. Silkis, A. S. Stankevich, V. N. Krasheninnikov, Yu A. Repeev, and D. V. Novikov. "MEASUREMENT OF PARAMETERS OF BROADBAND EMISSION USING MINI-SPECTROMETERS." NAUCHNOE PRIBOROSTROENIE 31, no. 4 (2021): 102–9. http://dx.doi.org/10.18358/np-31-4-i102109.

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On the basis of mini-spectrometers, a reference lamp of the SIRSH type with a known color temperature, and line spectrum sources, an inexpensive hardware complex has been created for measuring the emission parameters of heterodiodes and interference filters. Examples of recording the emission of heterodiodes (full width at half maximum is 17–30 nm) with a maximum of emission in the region of 659 and 764 nm and measurement of an interference filter (FWHM of the bandwidth is 12 nm) with a maximum transmission of 727 nm are given. The emission parameters of the SIRSH standard lamp are introduced into the program for measuring and processing data, due to which it is possible to significantly refine the value of the wavelength of the maximum emission and transmission.

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Miao, Qing Qing, Ying Mao Tang, Wen Wen Chen, et al. "Electrospun La³⁺-Doped ZnO Nanofibers with High Photocatalytic Activity for Rhodamine B Degradation." Advanced Materials Research 779-780 (September 2013): 337–42. http://dx.doi.org/10.4028/www.scientific.net/amr.779-780.337.

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Grape-like structure La3+-doped ZnO nanofibers with different doping concentrations were prepared by electrospinning-calcination technology. The resultant nanofibers were characterized by field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), photoluminescence spectrum (PL) and X-ray photoelectron spectrum (XPS) respectively. The photocatalytic activities of the nanofibers for the degradation of Rhodamine B (RhB) in aqueous solution were studied. Results show that the doping concentration of La3+ has an significant influence on the photocatalytic performance of the nanofibers, and 2 mol.% La3+ is the optimal doping concentration.

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Zhang, Michael, Kimberly Paragas, Jacob L. Bean, et al. "Retrievals on NIRCam Transmission and Emission Spectra of HD 189733b with PLATON 6, a GPU Code for the JWST Era." Astronomical Journal 169, no. 1 (2024): 38. https://doi.org/10.3847/1538-3881/ad8cd2.

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Abstract We present the 2.4–5.0 μm JWST/NIRCam emission spectrum of HD 189733b, along with an independent re-reduction of the previously published transmission spectrum at the same wavelengths. We use an upgraded version of PLanetary Atmospheric Tool for Observer Noobs (PLATON) to retrieve atmospheric parameters from both geometries. In transit, we obtain [M/H] = 0.53 − 0.12 + 0.13 and C/O = 0.41 − 0.12 + 0.13 , assuming a power-law haze and equilibrium chemistry with methane depletion. In eclipse, we obtain [M/H] = 0.68 − 0.11 + 0.15 and C/O = 0.43 − 0.05 + 0.06 , assuming a clear atmosphere and equilibrium chemistry without methane depletion. These results are consistent with each other, and with a rerun of our previously published joint retrieval of Hubble Space Telescope and Spitzer transmission and emission spectra. Accounting for methane depletion decreases the C/O ratio by 0.14/0.04 (transmission/emission), but changing the limb cloud parameterization does not affect the C/O ratio by more than 0.06. We detect H2O, CO2, CO, and H2S in both the NIRCam transmission and emission spectra, find that methane is depleted on the terminator, and confirm with VULCAN that photochemistry is a potential cause of this depletion. We also find tentative (1.8σ) evidence of a dayside thermal inversion at millibar pressures. Finally, we take this opportunity to introduce a new version of PLATON. PLATON 6 supports GPU computation, speeding up the code up to 10×. It also supports free retrievals using both volume mixing ratio and centered-log ratio priors; emission from planetary surfaces of different compositions; updated opacities at improved resolution; and Pareto smoothed importance sampling leave-one-out cross-validation.

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Woerd, H. van der, N. E. White, and S. M. Kahn. "X-ray Spectroscopy of the Ultra-soft Transient 4U1543-47." International Astronomical Union Colloquium 115 (1990): 205–8. http://dx.doi.org/10.1017/s0252921100012355.

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AbstractThe X-ray transient 4U1543-47 was observed in 1983 by the EXOSAT observatory near the maximum of an outburst. The X-ray spectrum was measured using a gas scintillation proportional counter (GSPC) and a transmission grating spectrometer (TGS). Two emission line features are resolved. A broad (FWHM ~2.7 keV) line at 5.9 keV is detected in the GSPC, which we interprete as a redshifted and broadened iron Kα line. The Une broadening and redshift may arise from either Compton scattering in a cool plasma with small optical depth (τ ≈ 5), or from Doppler and relativistic effects in the vicinity of a compact object. The spectrum below 2 keV, obtained with the TGS, shows evidence for a broad emission line feature at 0.74 keV, which may be an iron L-transition complex. However, we find that such an emission feature could be an artifact caused by an anomalously low interstellar absorption by neutral Oxygen. The continuum emission is extremely soft and is well described by an unsaturated Comptonized spectrum from a very cool plasma (kT = 0.84 keV) with large scattering depth (τ ≈ 27). The continuum spectrum is strikingly similar to that of black hole candidate LMC X-3.

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Bailhache, Simon, Julien Maillard, and Catherine Guigou-Carter. "Towards an alternative representation of indoor acoustic environment." Acta Acustica 6 (2022): 49. http://dx.doi.org/10.1051/aacus/2022045.

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The purpose of this investigation is to propose an alternative indoor sound spectrum based on objective and verifiable data, representative for an average household in Europe. It is obtained from the energetic sum of the emission spectra of sound sources commonly found in residential buildings, each weighted by its estimated occurrence time. Such a spectrum could then be used to evaluate airborne sound transmission performance.

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Yu, Xiao, Shijian Zhang, Ivan Sergeevich Egorov, et al. "Optimization of Transmission X-ray Target for Intense Pulsed Electron Beam Accelerators." Applied Sciences 12, no. 9 (2022): 4327. http://dx.doi.org/10.3390/app12094327.

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X-ray sources based on pulsed electron accelerators stimulate the development of bremsstrahlung converter designs. The numerical optimization of transmission-type X-ray targets for maximum X-ray output by pulsed electron beams was carried out in the present work. The targets featured a combination of a heavy element (tungsten or molybdenum) X-ray conversion layer and a titanium membrane that served as the vacuum window, thermal shielding for converter heat, and an electron dump. The energy spectrum of the electron beam generated via explosive emission was analyzed via the space-charge effect, and was utilized for the source sampling algorithm for electron transportation simulation with a Monte Carlo method for X-ray emission analysis. It was revealed that the transmission photon intensity of a mono-material target is primarily affected by the thickness of the target, and there exists an optimal target thickness within which the photon fluence is restricted by insufficient electron stopping; when exceeded, the extra thickness of the X-ray converter target imposes absorption and attenuates the generated X-ray. Analysis on dual-layer targets proved that this optimized converter target thickness, combined with a proper titanium window, produces the highest X-ray photon emissions.

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Yu, Xiao, Shijian Zhang, Ivan Sergeevich Egorov, et al. "Optimization of Transmission X-ray Target for Intense Pulsed Electron Beam Accelerators." Applied Sciences 12, no. 9 (2022): 4327. http://dx.doi.org/10.3390/app12094327.

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X-ray sources based on pulsed electron accelerators stimulate the development of bremsstrahlung converter designs. The numerical optimization of transmission-type X-ray targets for maximum X-ray output by pulsed electron beams was carried out in the present work. The targets featured a combination of a heavy element (tungsten or molybdenum) X-ray conversion layer and a titanium membrane that served as the vacuum window, thermal shielding for converter heat, and an electron dump. The energy spectrum of the electron beam generated via explosive emission was analyzed via the space-charge effect, and was utilized for the source sampling algorithm for electron transportation simulation with a Monte Carlo method for X-ray emission analysis. It was revealed that the transmission photon intensity of a mono-material target is primarily affected by the thickness of the target, and there exists an optimal target thickness within which the photon fluence is restricted by insufficient electron stopping; when exceeded, the extra thickness of the X-ray converter target imposes absorption and attenuates the generated X-ray. Analysis on dual-layer targets proved that this optimized converter target thickness, combined with a proper titanium window, produces the highest X-ray photon emissions.

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Tumborang, Abigail A., Jessica J. Spake, Heather A. Knutson, et al. "A Global Perspective with Updated Constraints on the Ultra-hot Jupiter WASP-19b: Atmospheric Properties and Stellar Activity." Astronomical Journal 168, no. 6 (2024): 296. https://doi.org/10.3847/1538-3881/ad863f.

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Abstract We present a detailed reanalysis of the atmospheric properties of WASP-19b, an ultra-hot Jupiter (1.14 M Jup, 1.41 R Jup) orbiting an active Sun-like star every 0.79 day. We reanalyze a transit and secondary eclipse of WASP-19b observed by the Hubble Space Telescope's Wide Field Camera 3 spectrograph (1.1–1.7 μm). When combined with Spitzer photometry at longer wavelengths, our analyses indicate the presence of water absorption features in both the planet's transmission and emission spectra, consistent with results from previously published studies. We jointly fit WASP-19b’s dayside emission and transmission spectra with a retrieval model in order to constrain its atmospheric composition, and explore the effect of stellar activity on its transmission spectrum in greater depth. We also compare our dayside emission spectrum to predictions from a general circulation model, and conclude that magnetic drag appears to be relatively unimportant in shaping WASP-19b’s atmospheric circulation. Lastly, we compare the size of WASP-19b’s dayside water absorption feature to the population of hot Jupiters with similar measurements, and show that it is located in the transitional irradiation regime where temperature inversions first begin to emerge. As in previous studies, we find that the current observations provide relatively weak constraints on this planet’s atmospheric properties. These constraints could be significantly improved by the addition of spectroscopically resolved observations at longer wavelengths with JWST/NIRSpec PRISM.

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Kawahara, Hajime, Yui Kawashima, Shotaro Tada, et al. "Differentiable Modeling of Planet and Substellar Atmosphere: High-resolution Emission, Transmission, and Reflection Spectroscopy with ExoJAX2." Astrophysical Journal 985, no. 2 (2025): 263. https://doi.org/10.3847/1538-4357/adcba2.

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Abstract Modeling based on differentiable programming holds great promise for astronomy, enabling advanced techniques such as gradient-based posterior sampling and optimization. This paradigm motivated us to develop ExoJAX, the first auto-differentiable spectrum model of exoplanets and brown dwarfs. ExoJAX directly calculates cross-sections as functions of temperature and pressure to minimize interpolation errors in high-dispersion spectra, although initial work focused on narrowband emission spectroscopy. Here, we introduce a fast, memory-efficient opacity algorithm and differentiable radiative transfer for emission, transmission, and reflection spectroscopy. In the era of data-rich JWST observations, retrieval analyses are often forced to bin high-resolution spectra due to computational bottlenecks. The new algorithm efficiently handles native-resolution data, preserving the full information content and dynamic range. The advances proposed in this paper enable broader applications, demonstrated by retrievals of GL 229B’s high-dispersion emission, WASP-39 b’s JWST mid-resolution transmission at original resolution (R ∼ 2700), and Jupiter’s reflection spectrum. We derive a C/O ratio for GL 229B consistent with its host star, constrain WASP-39 b’s radial velocity from molecular line structures, and infer Jupiter’s metallicity in line with previous estimates.

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Ponnar, M., and K. Pushpanathan. "Strong Ultra-Violet Absorption in Cu Doped CeO2 Nanospheres." Advanced Science Letters 24, no. 8 (2018): 5947–52. http://dx.doi.org/10.1166/asl.2018.12225.

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This article focuses the synthesis and characterization of copper doped cerium oxide nanospheres synthesized by chemical precipitation method. Synthesized nanopowders were characterized by means of X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, ultraviolet-visible spectrometer and photoluminescence spectrometer. X-ray diffraction study confirmed the copper doping without disturbing the face centred cubic structure of cerium oxide. Field emission scanning electron microscope and transmission electron microscope study also confirmed the existence of sphere like nanoparticles. The optical absorption spectrum shows that the synthesized samples exhibit strong absorption in ultraviolet region and also it confirmed the decrease in energy gap of cerium oxide on copper doping. The photoluminescence study revealed that the blue emission is attributed to the fast oxygen transportation of copper doped cerium oxide nanoparticles.

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S. A. Garakhin, I. S. Dubinin, S.Yu. Zuev, V.N. Polkovnikov, and N.I. Chkhalo. "Research and creation of broadband X-ray mirrors with a spectral transmission band coinciding with emission lines and the possibility of filtering." Technical Physics 92, no. 8 (2022): 927. http://dx.doi.org/10.21883/tp.2022.08.54552.118-22.

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The article considers broadband multilayer X-ray mirrors based on Mo/Be and Mo/Si structures with a transmission band coinciding with the Si Lα (13.5 nm) and Sn (13.5 nm) emission lines. The described structures are of great interest for the currently developed liquid source of EUV radiation, since they make it possible to increase the efficiency of the source-X-ray optical system due to the &quot;complete&quot; capture of emission lines. Keywords: extreme ultraviolet radiation, emission spectrum, laser spark, multilayer X-ray mirror.

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Dimple, P. Dutta, K. Tyagi A., and Sharma G. "Optical properties of sonochemically synthesized dysprosium doped CdO nanoparticles." Journal of Indian Chemical Society Vol. 87, Jan 2010 (2010): 23–28. https://doi.org/10.5281/zenodo.5775363.

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Chemistry Division, Materials Science Division, Bhabha Atomic Research Centre, Mumbai-400 085, India E-mail: dimpled@barc.gov.in, aktyagi@barc.gov.in               Fax : 91-22-25590457 Manuscript received 15 July 2009, accepted 20 July 2009 The undoped and dysprosium-doped CdO nanoparticles were prepared by sonochemical method in aqueous media and characterized with X-ray diffraction (XRD), transmission electron microscopy (TEM), UV-Vis diffuse reflectance spectrum, and photoluminescence spectra. The results of XRD Indicated that the obtained CdO : Dy3+ nanoparticles were well crystallized with a cubic phase. The TEM image illustrated that the CdO : Dy3+ nanoparticles were spherical with an average size around 40 nm. Under Irradiation of UV light, the emission spectrum of CdO : Dy3+ nanoparticles exhibited alongwith the host emission, the characteristic line emissions arising from the 4F9/2→ 6H3 (J = 13/2, 15/2) transitions of the Dy3+ Ions, with the dominating emission centered at ~ 580 nm. The optimum doping concentration for CdO : Dy3+ nanoparticles was determined to be 3 mol%.

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Eidmann, K., T. Kishimoto, P. Herrmann, et al. "Absolute soft x-ray measurements with a transmission grating spectrometer." Laser and Particle Beams 4, no. 3-4 (1986): 521–30. http://dx.doi.org/10.1017/s0263034600002202.

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Absolute measurements of the soft x-ray emission (50 eV < hv < 1000 eV) from laser plasmas were made with transmission gratings, including pinhole-grating combinations for spatially resolved spectroscopy. Kodak 101–01 film was absolutely calibrated as a function of wavelength with the help of a bolometer, the laser plasma being used as a source. An example of a quantitatively analyzed, space-resolved pinhole grating spectrum recorded on film will be shown.

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Suryanarayanan, Aswath, Frits Paerels, and Maurice Leutenegger. "The High-resolution Fe K Spectrum of Cygnus X-3." Astrophysical Journal 969, no. 2 (2024): 110. http://dx.doi.org/10.3847/1538-4357/ad4638.

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Abstract We analyze features of the Fe K spectrum of the high-mass X-ray binary Cygnus X-3. The spectrum was obtained with the Chandra High Energy Transmission Grating Spectrometer in the third diffraction order. The increased energy resolution of the third order enables us to fully resolve the Fe xxv Heα complex and the Fe xxvi Lyα lines. The emission-line spectrum shows the expected features of photoionization equilibrium, excited in the dense stellar wind of the companion star. We detect discrete emission from inner-shell transitions, in addition to absorption likely due to multiple unresolved transitions in lower ionization states. The emission-line intensity ratios observed in the range of the spectrum occupied by the Fe xxv n = 1–2 forbidden and intercombination lines suggest that there is a substantial contribution from resonantly scattered inner-shell emission from the Li- and Be-like ionization states. The Fe xxv forbidden and intercombination lines arise in the ionization zone closest to the compact object, and since they are not subject to radiative-transfer effects, we can use them in principle to constrain the radial velocity amplitude of the compact object. We infer that the results indicate a compact object mass of the order of the mass of the Wolf–Rayet companion star, but we note that the presence of resonantly scattered radiation from Li-like ions may complicate the interpretation of the He-like emission spectrum, and specifically of the radial velocity curve of the Fe xxv forbidden line.

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Fu, Ming, Ji Zhou, Bo Li, Qun Fang Xiao, Yue Hui Wang, and Long Tu Li. "Optical Properties of Nanocrystalline Ag Doped Silica Inverse Opals." Key Engineering Materials 336-338 (April 2007): 555–57. http://dx.doi.org/10.4028/www.scientific.net/kem.336-338.555.

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Nanocrystalline Ag doped silica inverse opals were prepared by a sol-gel chemistry method via templating of polystyrene colloidal crystals. The ordered structures of colloidal crystal templates and inverse opals are characterized by scanning electron microscopy. Ag nanocrystals size is estimated as 20~30nm by Scherrer Formula from X-ray diffraction. The color and the stop band of the inverse opals are characterized by transmission spectrum. And five emission peaks of the nanocrystalline silver clusters are observed from fluorescence spectrum.

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P. Huenemoerder, David, Bram Boroson, Norbert S. Schulz, et al. "Stellar Coronal Spectroscopy with the Chandra HETGS." Symposium - International Astronomical Union 219 (2004): 238–42. http://dx.doi.org/10.1017/s0074180900182178.

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Spectroscopy with the Chandra High Energy Transmission Grating Spectrometer (HETGS) provides details on X-ray emission and activity from young and cool stars through resolution of emission lines from a variety of ions. We are beginning to see trends in activity regarding abundances, emission measures, and variability. Here we contrast spectra of TV Crt, a weak-lined T Tauri star (WTT), with TW Hya, a Classical T Tauri star (CTT). TV Crt has a spectrum more like magnetic activity driven coronae, relative to the TW Hya spectrum, which we have interpreted as due to accretion-produced X-rays. We have also observed the long period system, IM Pegasi to search for rotational modulation, and to compare activity in a long period active binary to shorter period systems and to the pre-main sequence stars. We detected no rotational modulation, but did see long-duration flares.

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Campajola, Marcello, Francesco Di Capua, Pierluigi Casolaro, Ettore Sarnelli, and Alberto Aloisio. "Radiation Damage in Polyethylene Naphthalate Thin-Film Scintillators." Materials 15, no. 19 (2022): 6530. http://dx.doi.org/10.3390/ma15196530.

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This paper describes the scintillation features and the radiation damage in polyethylene naphthalate 100 µm-thick scintillators irradiated with an 11 MeV proton beam and with a 1 MeV electron beam at doses up to 15 and 85 Mrad, respectively. The scintillator emission spectrum, optical transmission, light yield loss, and scintillation pulse decay times were investigated before and after the irradiation. A deep blue emission spectrum peaked at 422 nm, and fast and slow scintillation decay time constants of the order of 1–2 ns and 25–30 nm, respectively, were measured. After irradiation, transmittance showed a loss of transparency for wavelengths between 380 and 420 nm, and a light yield reduction of ~40% was measured at the maximum dose of 85 Mrad.

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Bao, Jiazhen, Yifeng Cao, and Qian Huang. "Maximum gain optimization of thulium-doped fiber amplifier based on genetic algorithm for peak gain spectrum at 1800- 2000nm." Applied and Computational Engineering 10, no. 1 (2023): 72–78. http://dx.doi.org/10.54254/2755-2721/10/20230143.

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The optical fiber amplifier doped with rare earth elements has the characteristics of high gain, high doping concentration and short length. Compared with other fiber optic systems, the fiber used is shorter, also known as lumped fiber amplifier. At present, Er, Pr, Tm, Nd and Yb doped fiber amplifiers and lasers are mainly studied more. To further extend the transmission distance, improve the transmission quality and increase the transmission capacity, it is very important for the research of fiber amplifier. In this research, using a two-level structure, we investigate the maximum of the peak gain of the gain spectrum of a thulium-doped broadband fiber amplifier in the 1800-2000 nm wavelength range. Signal gain is inversely proportional to fiber length, doping concentration, and pump power in both the absorption spectrum and the emission spectrum, as shown by the relationship diagram of signal gain with these variables. And through the genetic algorithm data optimization, we get that when the fiber length is 2.2 m, the maximum gain is 42.7 dB.

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Gafur, Abdul, and M. S. Islam. "Optimization of Q-Values for Coherent Optical Transmission Network." Rajshahi University Journal of Science and Engineering 43 (December 31, 2015): 63–72. http://dx.doi.org/10.3329/rujse.v43i0.26156.

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In this paper we have analyzed the Gaussian Non-linear Interference (GNLI) spectrum considering non identical channels, non-identical links and Amplified Spontaneous Emission (ASE) noise power spectrum for Coherent Optical Transmission Network (COTN) to calculate the Optical Signal to Noise Ratio (OSNR) and Quality (Q) values. In this study, three different Baud rate values (13.875Gbaud, 27.75Gbaud, and 55.5Gbaud) are considered to compute the Q values and OSNR in the COTN. Consequently, the COTN produces 111 Gb/s, 222 Gb/s and 444 Gb/s line rates for three different Baud rate values (13.875Gbaud, 27.75Gbaud, and 55.5Gbaud) respectively in PM-16QAM modulation format. It is confirmed that the OSNR is always greater than Q values. It is also found that the differences between OSNR and Q are 0.23dB, 1.73dB, and 3.24dB for 111Gb/s, 222Gb/s and 444Gb/s line rates respectively. Here transmission of launch power per span, number of channels, number of spans and the fiber dispersion in the optical link are considered.

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Han, Yan Xia, Qian Nan Li, Hai Yun Shen, and Qiu Hua Yang. "Synthesis, Characterization and Optical Property of KLaF₄:Ce³⁺ Nano Particle." Applied Mechanics and Materials 778 (July 2015): 183–86. http://dx.doi.org/10.4028/www.scientific.net/amm.778.183.

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Ce3+doped cubic KLaF4system was synthesized by co-precipitation method. The sample was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), UV-Vis spectrophotometer and fluorescence spectrophotometer. The result indicated the nanoparticle diameter of KLaF4:Ce3+was 12.5 nm. The KLaF4:Ce3+had a stronger absorption at 250 nm, which could be explained by d elecronic transition of Ce3+. The maximum emission peak of KLaF4:Ce3+was 355 nm in its luminescent spectrum, and emission band of Ce3+also belonged to 5d→4f transition.

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Tran Van, Khai, Vinh Nguyen Quang, Thang Le Van, and Phong Mai Thanh. "EFFECT OF TEMPERATURE ON THE STRUCTURE AND PROPERTIES OF Fe2O3/GRAPHENE NANOCOMPOSITES SYNTHESIZED BY HYDROTHERMAL METHOD." Vietnam Journal of Science and Technology 57, no. 3A (2019): 150. http://dx.doi.org/10.15625/2525-2518/57/3a/14105.

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A simple and straightforward approach was used to prepare Fe2O3/graphene nanocomposites with different temperature conditions. The nanocomposites were characterized by X-ray diffraction (XRD), Raman spectroscopy, field emission scanning microscopy (FE-SEM), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS) and photoluminescence (PL). The results show that Fe2O3 nanoparticles with size in range of 60-100 nm are anchored on the surface and filled between the graphene nanosheets at hydrothermal reaction. The PL spectrum exhibits the emission peaks appeared at ~ 650 nm and ~ 720 nm.

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Camarillo-Avilés, A., E. Hernández-Escobar, R. López-Estopíer, et al. "The nonlinear optical loop mirror: soliton and noise-like pulse emission in a figure-eight fiber laser." Suplemento de la Revista Mexicana de Física 2, no. 1 Jan-Mar (2021): 54–59. http://dx.doi.org/10.31349/suplrevmexfis.2.1.54.

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In this article, a symmetrical nonlinear optical loop mirror (NOLM) exhibiting a polarization-dependent transmission is evaluated to generate optical pulse emission in a figure-eight fiber laser in the soliton and noise-like pulse (NLP) regimes. The NOLM structure relies on a 50:50 fiber coupler, a loop with highly twisted single-mode optical fiber and a quarter-wave retarder (QWR) to break the polarization asymmetry. The pulse operation regime is determined by properly adjusting the NOLM low-power transmission, which is easily realized by the rotation of the QWR angle. Soliton pulses of 1.48 ps pulse duration and peak power of 18 W were observed with a peak to peak separation of 1.25 µs, corresponding to a fundamental cavity repetition rate of 0.8 MHz. Moreover, by incrementing the NOLM low-power transmission, NLP emission is generated exhibiting a wide and smooth spectrum of 8.5 nm bandwidth.

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Yang, Yuanheng, Guo Chen, Fei Yan, Xianyu Tan, and Jianghui Ji. "Evidence for Nightside Water Emission Found in Transit of Ultra-hot Jupiter WASP-33 b." Astrophysical Journal Letters 971, no. 1 (2024): L8. http://dx.doi.org/10.3847/2041-8213/ad65cf.

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Abstract To date, the dayside thermal structure of ultra-hot Jupiters (UHJs) is generally considered to be inverted, but their nightside thermal structure has been less explored. Here, we explore the impact of nightside thermal emission on high-resolution infrared transmission spectroscopy, which should not be neglected, especially for UHJs. We present a general equation for the high-resolution transmission spectrum that includes planetary nightside thermal emission. This provides a new way to infer the thermal structure of the planetary nightside with high-resolution transmission spectroscopy. Using the cross-correlation technique, we find evidence for the presence of an H2O emission signature on the UHJ WASP-33 b during the transit, indicating an inverted temperature structure on its nightside. Such a result suggests a stronger heat transport through the circulation than currently expected. An alternative explanation is that the rotating visible hemisphere during transit leads to the potential contribution of the limb and dayside atmospheres to the detected emission signature. In the future, the combination of high-resolution, full-phase-curve spectroscopic observations and general circulation models will hopefully solve this puzzle and provide a complete picture of the three-dimensional nature of the chemistry, circulation, and thermal structure of UHJs.

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TOUFIQ, ARBAB MOHAMMAD, FENGPING WANG, QURAT-UL-AIN JAVED, QUANSHUI LI, and YAN LI. "PHOTOLUMINESCENCE SPECTRA AND MAGNETIC PROPERTIES OF HYDROTHERMALLY SYNTHESIZED MnO2 NANORODS." Modern Physics Letters B 27, no. 29 (2013): 1350211. http://dx.doi.org/10.1142/s0217984913502114.

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In this paper, single crystalline tetragonal MnO 2 nanorods have been synthesized by a simple hydrothermal method using MnSO 4⋅ H 2 O and Na 2 S 2 O 8 as precursors. The crystalline phase, morphology, particle sizes and component of the as-prepared nanomaterial were characterized by employing X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED) and energy-dispersive X-ray spectroscopy (EDS). The photoluminescence (PL) emission spectrum of MnO 2 nanorods at room temperature exhibited a strong ultraviolet (UV) emission band at 380 nm, a prominent blue emission peak at 453 nm as well as a weak defect related green emission at 553 nm. Magnetization (M) as a function of applied magnetic field (H) curve showed that MnO 2 nanowires exhibited a superparamagnetic behavior at room temperature which shows the promise of synthesized MnO 2 nanorods for applications in ferrofluids and the contrast agents for magnetic resonance imaging. The magnetization versus temperature curve of the as-obtained MnO 2 nanorods shows that the Néel transition temperature is 94 K.

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Talam, Satyanarayana, Srinivasa Rao Karumuri, and Nagarjuna Gunnam. "Synthesis, Characterization, and Spectroscopic Properties of ZnO Nanoparticles." ISRN Nanotechnology 2012 (May 22, 2012): 1–6. http://dx.doi.org/10.5402/2012/372505.

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ZnO nanoparticles have been synthesized by precipitation method from Zinc nitrate. The powder was characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, selected-area electron diffraction, UV-vis optical absorption, and photoluminescence spectroscopy analyses. XRD patterns showed that ZnO nanoparticles have hexagonal unit cell structure. SEM and TEM pictures reveal the morphology and particle size of prepared ZnO nanoparticles. The UV-vis absorption spectrum shows an absorption band at 355 nm due to ZnO nanoparticles. The photoluminescence spectrum exhibits two emission peaks one at 392 nm corresponding to band gap excitonic emission and another located at 520 nm due to the presence of singly ionized oxygen vacancies. The synthesis method has potential for application in manufacturing units due to ease processing and more economical reagents.

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Zhang, Junhao, Yuhui Wu, Jia Zhu, Shaoxing Huang, Dongjing Zhang, and Qinghuan Yin. "Synthesis and optical properties of self-assembled flower-like CdS architectures by mixed solvothermal process." Open Chemistry 8, no. 5 (2010): 1027–33. http://dx.doi.org/10.2478/s11532-010-0075-2.

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AbstractSelf-assembled CdS architectures with flower-like structures have been synthesized by a mixed solvothermal method using ethylene glycol and oleic acid as the mixed solvent at 160°C for 12 h. The results of X-ray diffraction (XRD) patterns, field-emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) images indicate that the product exists as the hexagonal wurtzite phase and conatins of larger numbers of flower-like CdS architectures with diameters of 1.8–3 μm. The selected-area electron diffraction (SAED) pattern and the high resolution transmission electron microscope (HRTEM) image reveal that the grain has better crystallinity. The optical properties of flower-like CdS architectures were also investigated by ultraviolet-visable (UV-vis) and photoluminescence spectroscopy at room temperature. A strong peak at 490 nm is shown in the UV-vis absorption, while an emission at 486 nm and another strong emission at 712 nm are shown in the PL spectrum.

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Sarker, Sohag, Laila Arzuman Ara, Tahsin Alam, and Tarun Debnath. "Design and Analysis of MIMO F-OFDM Systems for 5G and Beyond Wireless Communications." International Journal of Recent Technology and Engineering (IJRTE) 10, no. 2 (2021): 203–10. http://dx.doi.org/10.35940/ijrte.b6274.0710221.

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F-OFDM (Filtered-OFDM) is a flexible waveform that has been considered suitable for 5G and beyond systems for its improved spectrum utilization, moderates PAPR, low OOB emission, multiple asynchronous sub-band transmission, and high robustness to frequency selectivity. It can attain a desirable balance between frequency and time localizations for narrow bandwidths. It is also MIMO friendly. In this paper, a comprehensive design and analysis have been made to evaluate the performance of MIMO (4×4) CP-OFDM and F-OFDM systems for message bits transmission using several digital modulation techniques (16-QAM, 16-PSK, 16-DPSK, 64-QAM, 64-PSK, and 64-DPSK), RA channel coding, different windowed (Hanning, Hamming, Blackman, Blackman-Harris, RRC) sinc FIR filters for length N = 513, and MMSE signal detection technique. From MATLAB based simulation results, it is observed that F-OFDM reduces spectrum leakage thus enhances spectrum efficiency than conventional CP-OFDM. F-OFDM based system offers lower BER (Bit Error Rate) performance than CP-OFDM based system.

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Sohag, Sarker, Arzuman Ara Laila, Alam Tahsin, and Debnath Tarun. "Design and Analysis of MIMO F-OFDM Systems for 5G and Beyond Wireless Communications." International Journal of Recent Technology and Engineering (IJRTE) 10, no. 2 (2021): 203–10. https://doi.org/10.35940/ijrte.B6274.0710221.

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F-OFDM (Filtered-OFDM) is a flexible waveform that has been considered suitable for 5G and beyond systems for its improved spectrum utilization, moderates PAPR, low OOB emission, multiple asynchronous sub-band transmission, and high robustness to frequency selectivity. It can attain a desirable balance between frequency and time localizations for narrow bandwidths. It is also MIMO friendly. In this paper, a comprehensive design and analysis have been made to evaluate the performance of MIMO (4×4) CP-OFDM and F-OFDM systems for message bits transmission using several digital modulation techniques (16-QAM, 16-PSK, 16-DPSK, 64-QAM, 64-PSK, and 64-DPSK), RA channel coding, different windowed (Hanning, Hamming, Blackman, Blackman-Harris, RRC) sinc FIR filters for length N = 513, and MMSE signal detection technique. From MATLAB based simulation results, it is observed that F-OFDM reduces spectrum leakage thus enhances spectrum efficiency than conventional CP-OFDM. F-OFDM based system offers lower BER (Bit Error Rate) performance than CP-OFDM based system.

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Berardo, David, Julien de Wit, and Benjamin V. Rackham. "Empirically Constraining the Spectra of Stellar Surface Features Using Time-resolved Spectroscopy." Astrophysical Journal Letters 961, no. 1 (2024): L18. http://dx.doi.org/10.3847/2041-8213/ad1b5b.

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Abstract Transmission spectroscopy is currently the technique best suited to study a wide range of planetary atmospheres, leveraging the filtering of a star’s light by a planet’s atmosphere rather than its own emission. However, as both a planet and its star contribute to the information encoded in a transmission spectrum, an accurate accounting of the stellar contribution is pivotal to enabling robust atmospheric studies. As current stellar models lack the required fidelity for such accounting, we investigate here the capability of time-resolved spectroscopy to yield high-fidelity, empirical constraints on the emission spectra of stellar surface heterogeneities (i.e., spots and faculae). Using TRAPPIST-1 as a test case, we simulate time-resolved JWST/NIRISS spectra and demonstrate that with a blind approach incorporating no physical priors, it is possible to constrain the photospheric spectrum to ≤0.5% and the spectra of stellar heterogeneities to within ≲10%, a precision that enables photon-limited (rather than model-limited) science. Now confident that time-resolved spectroscopy can propel the field in an era of robust high-precision transmission spectroscopy, we introduce a list of areas for future exploration to harness its full potential, including wavelength dependency of limb darkening and hybrid priors from stellar models as a means to further break the degeneracy between the position, size, and spectra of heterogeneities.

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Castañeda, L. "Transparent conductive stannic oxide coatings employing an ultrasonic spray pyrolysis technique: The relevance of the molarity content in the aerosol solution for improvement the electrical properties." Journal of Semiconductors 43, no. 2 (2022): 022802. http://dx.doi.org/10.1088/1674-4926/43/2/022802.

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Abstract Highly transparent conductive stoichiometric nanocrystalline stannic oxide coatings were deposited onto Corning® EAGLE XG® slim glass substrates. Including each coating, it was deposited for various concentrations in the aerosol solution with the substrate temperature maintained at 623.15 K by an ultrasonic spray pyrolysis (USP) technique. Nitrogen was employed both as the solution carrier in addition to aerosol directing gas, maintaining its flow rates at 3500.0 and 500.0 mL/min, respectively. The coatings were polycrystalline, with preferential growth along the stannic oxide (112) plane, irrespective of the molarity content in the spray solution. The coating prepared at 0.2 M, a concentration in the aerosol solution, showed an average transmission of 60% in the visible light region spectrum with a maximum conductivity of 24.86 S/cm. The coatings deposited exhibited in the general photoluminescence spectrum emission colors of green, greenish white, and bluish white calculated on the intensities of the excitonic and oxygen vacancy defect level emissions.

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Shimokawa, CAK, B. Sullivan, ML Turbino, CJ Soares, and RB Price. "Influence of Emission Spectrum and Irradiance on Light Curing of Resin-Based Composites." Operative Dentistry 42, no. 5 (2017): 537–47. http://dx.doi.org/10.2341/16-349-l.

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SUMMARY Purpose: This study examined the influence of different emission spectra (single-peak and broad-spectrum) light-curing units (LCUs) delivering the same radiant exposures at irradiance values of 1200 or 3600 mW/cm2 on the polymerization and light transmission of four resin-based composites (RBCs). Methods and Materials: Two prototype LCUs that used the same light tip, but were either a single-peak blue or a broad-spectrum LED, were used to deliver the same radiant exposures to the top surfaces of the RBCs using either standard (1200 mW/cm2) or high irradiance (3600 mW/cm2) settings. The emission spectrum and radiant power from the LCUs were measured with a laboratory-grade integrating sphere coupled to a spectrometer, and the light beam was assessed with a beam profiler camera. Four RBCs (Filtek Supreme Ultra A2, Tetric EvoCeram A2, Tetric EvoCeram T, and TPH Spectra High Viscosity A2) were photoactivated using four different light conditions: single-peak blue/standard irradiance, single-peak blue/high irradiance, broad-spectrum/standard irradiance, and broad-spectrum/high irradiance. The degree of conversion (N=5) and microhardness at the top and bottom of 2.3-mm-diameter by 2.5-mm-thick specimens (N=5) were analyzed with analysis of variance and Tukey tests. The real-time light transmission through the RBCs was also measured. Results: For all light conditions, the 2.3-mm-diameter specimens received a homogeneous irradiance and spectral distribution. Although similar radiant exposures were delivered to the top surfaces of the RBCs, the amount of light energy emitted from the bottom surfaces was different among the four RBCs, and was also greater for the single-peak lights. Very little violet light (wavelengths below 420 nm) reached the bottom of the 2.5-mm-thick specimens. The degree of conversion and microhardness results varied according to the RBC (p&lt;0.05). The RBCs that included alternative photoinitiators had greater microhardness values at the top when cured with broad-spectrum lights, while at the bottom, where little violet light was observed, the results were equal or higher when they were photoactivated with single-peak blue lights. With the exception of the microhardness at the top of TPH, equivalent or higher microhardness and degree-of-conversion values were achieved at the bottom surface when the standard (1200 mW/cm2) irradiance levels were used compared to when high irradiance levels were used. Conclusions: Considering the different behaviors of the tested RBCs, the emission spectrum and irradiance level influenced the polymerization of some RBCs. The RBCs that included alternative photoinitiators produced greater values at the top when cured with broad-spectrum lights, while at the bottom, results were equal or higher for the RBCs photoactivated with single-peak blue lights.

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Kim, Hyoun Woo, and S. H. Shim. "Synthesis and Properties of SnO₂ One-Dimensional Nanomaterials on Pt-Coated Substrates." Materials Science Forum 517 (June 2006): 21–24. http://dx.doi.org/10.4028/www.scientific.net/msf.517.21.

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We have synthesized the belt-like structures of tin oxide (SnO2) by carrying out the thermal evaporation of solid Sn powders. We have analyzed the samples with scanning electron microscopy, X-ray diffraction, transmission electron microscopy and photoluminescence (PL). The obtained nanobelts were single crystalline with a tetragonal rutile structure. PL spectrum exhibited the visible light emission. We have discussed the possible growth mechanisms.

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Meng, Xiao Min, and Ai Min He. "Synthesis and Optical Properties of Hollow Spheres Self-Assembled by ZnO Nanocrystals." Advanced Materials Research 236-238 (May 2011): 2019–23. http://dx.doi.org/10.4028/www.scientific.net/amr.236-238.2019.

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Nano-sized hollow spheres self-assembled by ZnO nanocrystals have been prepared by microemulsion method with dodecyl benzene sulfonic acid sodium salt (DBS) as the modifying and protecting agent. The product was characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high High-resolution electron microscopy (HRTEM) energy dispersive spectroscopy (EDS) and photoluminescence (PL) spectra. The results showed that the hollow sphere was composed of ZnO nanocrystals. And the PL spectrum showed a different emission at 438 nm. After heated the product, PL emission peak changed. A possible formation mechanism was also proposed.

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Tian, Hai Yan, Hai Yun Shen, Qiu Hua Yang, and Xue Juan Wang. "Synthesis, Characterization and Fluorescent Properties of Complex Fluoride BaNiF₄: Ce³⁺." Advanced Materials Research 465 (February 2012): 56–60. http://dx.doi.org/10.4028/www.scientific.net/amr.465.56.

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The complex fluoride BaNiF4:Ce3+ was synthesized by reflux method using ethylene glycol as reaction solvent at its boiling point temperature. The sample was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and fluorescence spectrophotometer. The results indicated that the mean particle diameter of BaNiF4:Ce3+ was 53.8 nm. Only adsorption oxygen (α oxygen) existed on the surface of BaNiF4: Ce3+ and the content of surface oxygen was ≤5%. The maximum emission peak of BaNiF4:Ce3+ was 350 nm in its luminescent spectrum, and emission band of Ce3+ belonged to 5d→4f transition.

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Huang, Jun, Xiao Jing Lv, Mi Ouyang, Bin Hu, and Cheng Zhang. "Atmospheric Pressure Synthesis of ZnO Nanotubes by Aqueous Solution Route." Advanced Materials Research 669 (March 2013): 189–93. http://dx.doi.org/10.4028/www.scientific.net/amr.669.189.

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Single-crystalline ZnO nanotubes were fabricated via a simple aqueous solution method under low temperature and atmospheric pressure conditions. X-ray powder diffraction (XRD), field-emission scanning electron microscopy (FE-SEM) and high-resolution transmission electron microscopy (HR-TEM) equipped with the selected area electron diffraction (SAED) setup were used to analyze the crystal structure, surface morphology and inner structure of ZnO nanotubes. Photoluminescence (PL) and UV-visible absorption spectra were carried out to investigate optical properties of ZnO nanotubes. The results indicate ZnO nanotubes only exhibit sharp and strong near ultraviolet emission at 363 nm according to PL spectrum.

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Su, Yong, Xia Meng, Yiqing Chen, et al. "Synthesis and Characterization of Al2O3/SiO2 Coaxial Nanowire Heterostructures with Periodical Twinning Structures." Journal of Nanoscience and Nanotechnology 8, no. 7 (2008): 3483–86. http://dx.doi.org/10.1166/jnn.2008.114.

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Al2O3/SiO2 coaxial nanowire heterostructures were synthesized on a silicon substrate by a simple thermal evaporation method. The structure and morphology of the as-synthesized nanostructure were characterized using scanning electron microscopy and transmission electron microscopy. The growth of Al2O3/SiO2 coaxial nanowire heterostructures follows a vapor-solid (VS) process. Studies indicate that typical nanostructure consists of single twinning-crystalline Al2O3 nanowires (core) with diameter of about 50 nm and amorphous SiO2 shell. Photoluminescence properties were also investigated at room temperature. The photoluminescence spectrum reveals the product has a blue emission band and two UV emission bands.

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Lu, Xiu Zhen, Ming Tao Xu, Yan Yan Chang, and Bo Peng. "Synthesis of Oriented ZnO Nanofibers Using Electrospun Method on Si (100) Substrate." Advanced Materials Research 1033-1034 (October 2014): 1094–98. http://dx.doi.org/10.4028/www.scientific.net/amr.1033-1034.1094.

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ZnO nanofibers on Si (100) were synthesized by electrospun and calcination process. The morphology, structure and optical performance were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Raman spectroscopy and photoluminescence (PL) spectrum. XRD results indicated ZnO nanofibers on Si (100) wafer calcined at 600 °C had a preferred growth orientation of (002) direction. ZnO nanofibers calcinated at 600 °C had an excellent crystalline structure with the diameters ranging from 70 to 150 nm. Defect states in the ZnO nanofibers were observed, which resulted in the green emission in PL spectrum.

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Journal articles on the topic 'Emission and transmission spectrum'

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