In the above article <xref ref-type="bibr" rid="ref1">1 , a difference in the definitions of our simulated reflectance (with respect to instantaneous TOA radiance) and the operational MERSI-II L1 ...reflectance (with respect to solar constant) causes errors in their direct comparisons.
The use of X‐ray and neutron reflectivity has been generalized worldwide for scientists who want to determine specific physical properties (such as electron‐density profile, scattering‐length ...density, roughness and thickness) of films less than 200 nm thick deposited on a substrate. This paper describes a freeware program named REFLEX, which is a standalone program dedicated to the simulation and analysis of X‐ray and neutron reflectivity from multilayers. This program was first written two decades ago and has been constantly improved since, but never published until now. The latest version of REFLEX covers generalized types of calculation of reflectivity curves including both neutron and X‐ray reflectivity. In the case of X‐rays, the program can deal with both s and p polarization, which is quite important in the soft X‐ray region where the two polarizations can yield different results. Neutron reflectivity is calculated within the framework of non‐spin‐polarized neutrons. REFLEX has also been designed to include any type of fluid (such as supercritical CO2) on top of the analysed film and includes corrections of the footprint effect for analysis on an absolute scale.
REFLEX is a user‐friendly program dedicated to the analysis of specular X‐ray (soft and hard) and neutron reflectivity measurements.
GenX is a versatile program using the differential evolution algorithm for fitting X‐ray and neutron reflectivity data. It utilizes the Parratt recursion formula for simulating specular reflectivity. ...The program is easily extensible, allowing users to incorporate their own models into the program. This can be useful for fitting data from other scattering experiments, or for any other minimization problem which has a large number of input parameters and/or contains many local minima, where the differential evolution algorithm is suitable. In addition, GenX manages to fit an arbitrary number of data sets simultaneously. The program is released under the GNU General Public License.
In the San Francisco Bay Area, precipitation occurs in the wintertime, mostly as rain. Wintertime rainfall can be further classified into cold or stratiform rain with a typical radar bright band (BB) ...signature and warm orographic rain with the absence of a radar BB. Vertical pointing S-band profiler radar and disdrometer measurements from two of National Oceanic and Atmospheric Administration (NOAA)'s hydrometeorology testbed (HMT) sites in California are used to study the differences in microphysical properties between these two types of rain and their implications in radar rainfall estimation. A methodology has been developed to discriminate nonbright band (NBB) rainfall from BB rainfall using reflectivity (Z) and differential reflectivity (<inline-formula> <tex-math notation="LaTeX">Z_{\mathrm { DR}} </tex-math></inline-formula>) computed from disdrometer data. Delineating the two rainfall types in this way allowed for an algorithm to be applied to the radar scans to identify rainfall types and apply appropriate reflectivity-based and specific differential phase (<inline-formula> <tex-math notation="LaTeX">K_{\mathrm { DP}} </tex-math></inline-formula>)-based rainfall estimators. Recently, a gap-filling X-band weather radar with dual-polarization capabilities was deployed in the San Francisco Bay Area in Santa Rosa to aid in weather monitoring and provide high-resolution quantitative precipitation estimation (QPE) products. When applied to real radar observations, this method shows great potential for improving the QPE compared to traditional operational products which more often tend to underestimate rainfall in the California coastal region.
Abstract
Full-angle distributed Bragg reflectors (DBRs) consisting of numerous sub-DBRs with discrete central wavelengths have been developed to enhance performance of GaN-based flip-chip mini ...light-emitting diodes (FC mini-LEDs). However, relatively low reflectivity of full-angle DBRs at large angle incidence restricts further enhancement in performance of FC mini-LEDs. Here, we introduce a reflectivity optimization strategy for constructing high-reflectivity multiple-stack DBRs by rationally engineering the number of sub-DBRs and adjusting central wavelength distribution of sub-DBRs. Based on the reflectivity optimization strategy, we devise a Ti
3
O
5
/SiO
2
quintuple-stack DBR which is composed of five sub-DBRs. Our quintuple-stack DBR maintains a high reflectivity (>97.5%) over a wide range of incident angles of light. Notably, compared with the full-angle DBR, our quintuple-stack DBR exhibits higher reflectivity at large angle incidence and thinner multilayer thickness. Furthermore, we demonstrate two types of GaN-based blue FC mini-LEDs with indium-tin oxide (ITO)/quintuple-stack DBR and ITO/full-angle DBR p-type ohmic contacts. Benefiting from superior reflection performance, blue FC mini-LED with ITO/quintuple-stack DBR achieves an enhancement of ∼5.8% in light output power at 10 mA, in comparison with blue FC mini-LED with ITO/full-angle DBR. Our work signifies an advancement towards high-reflectivity DBRs, which enables higher-performance FC mini-LEDs.
Many interesting physical, chemical and biological phenomena occur at interfaces between nanometre-scale layers of soft condensed matter. These often complex systems lend themselves to be studied by ...X-ray reflectivity (XRR) and neutron reflectivity (NR). The application of these techniques to such systems is extremely widespread and provides unique insights into their structure and dynamics. This review presents a snapshot of recent activity in this research area and identifies trends in the application of XRR and NR to novel, unusual or highly complex sample systems. Although the majority of research using these techniques is investigating variations on ‘traditional’ systems, supported by progress in instrumentation, advance sample environment and computational tools, NR and XRR have begun to produce singular insights into areas such as atmospheric science, real biological systems (cells and bacteria), oil–water interfaces or industrial problems (rheology, packaging or durability of nanomaterials).
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Element Specific Monolayer Depth Profiling Macke, Sebastian; Radi, Abdullah; Hamann-Borrero, Jorge E. ...
Advanced materials (Weinheim),
10/2014, Letnik:
26, Številka:
38
Journal Article
Recenzirano
The electronic phase behavior and functionality of interfaces and surfaces in complex materials are strongly correlated to chemical composition profiles, stoichiometry and intermixing. Here a novel ...analysis scheme for resonant X‐ray reflectivity maps is introduced to determine such profiles, which is element specific and non‐destructive, and which exhibits atomic‐layer resolution and a probing depth of hundreds of nanometers.
Microplastics (<5 mm) have been documented in environmental samples on a global scale. While these pollutants may enter aquatic environments via wastewater treatment facilities, the abundance of ...microplastics in these matrices has not been investigated. Although efficient methods for the analysis of microplastics in sediment samples and marine organisms have been published, no methods have been developed for detecting these pollutants within organic-rich wastewater samples. In addition, there is no standardized method for analyzing microplastics isolated from environmental samples. In many cases, part of the identification protocol relies on visual selection before analysis, which is open to bias. In order to address this, a new method for the analysis of microplastics in wastewater was developed. A pretreatment step using 30% hydrogen peroxide (H2O2) was employed to remove biogenic material, and focal plane array (FPA)-based reflectance micro-Fourier-transform (FT-IR) imaging was shown to successfully image and identify different microplastic types (polyethylene, polypropylene, nylon-6, polyvinyl chloride, polystyrene). Microplastic-spiked wastewater samples were used to validate the methodology, resulting in a robust protocol which was nonselective and reproducible (the overall success identification rate was 98.33%). The use of FPA-based micro-FT-IR spectroscopy also provides a considerable reduction in analysis time compared with previous methods, since samples that could take several days to be mapped using a single-element detector can now be imaged in less than 9 h (circular filter with a diameter of 47 mm). This method for identifying and quantifying microplastics in wastewater is likely to provide an essential tool for further research into the pathways by which microplastics enter the environment.
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