Search

Mosaic crystals, with their high integrated reflectivities, are widely employed in spectrometers used to diagnose high energy density systems. X-ray Thomson scattering (XRTS) has emerged as a powerful diagnostic tool of these systems, providing in principle direct access to important properties such as the temperature via detailed balance. However, the measured XRTS spectrum is broadened by the spectrometer instrument function (IF), and without careful consideration of the IF one risks misdiagnosing system conditions. Here, we consider in detail the IF of 40 and 100 μ m mosaic Highly Annealed Pyrolytic Graphite crystals, and how the broadening varies across the spectrometer in an energy range of 6.7–8.6 keV. Notably, we find a strong asymmetry in the shape of the IF toward higher energies. As an example, we consider the effect of the asymmetry in the IF on the temperature inferred via XRTS for simulated 80 eV CH plasmas and find that the temperature can be overestimated if an approximate symmetric IF is used. We, therefore, expect a detailed consideration of the full IF will have an important impact on system properties inferred via XRTS in both forward modeling and model-free approaches. [ABSTRACT FROM AUTHOR]

This study investigated the dissociation after the Xe 4d Auger decay of weak-bonding XeF2 molecules by multielectron–ion coincidence spectroscopy using a magnetic bottle electron spectrometer. Fragmentations from the XeF22+ states were clarified in the Auger spectra coincident with individual ion species. It was observed that the two-hole population led by the Auger decay was not directly inherited during the fragmentation of XeF22+. Furthermore, the dissociations of XeF23+ states produced by the double Auger decay were investigated. [ABSTRACT FROM AUTHOR]

The virtually imaged phased array (VIPA) spectrometer uses the orthogonal dispersion method and has the advantages of compact structure, high spectral resolution, and wide wavelength coverage. It has been widely used in different fields. However, due to the non-linear dispersion of the VIPA etalon and the cross-dispersion structure of the VIPA spectrometer, simple and high-accuracy wavelength calibration remains a challenge. In this paper, a new and simple five-parameter spectrogram model is developed by simplifying the phase-matching equation of the VIPA etalon and considering the angle between the camera and dispersion direction, which can achieve a frequency accuracy better than one pixel. The performance of the model is demonstrated by measuring the CO2 absorption spectrum in the range of 1.42 to 1.45 μm using a self-designed near-infrared VIPA spectrometer. The reported method is simple and easy to solve with high accuracy, which is conducive to promoting the application of VIPA spectrometers in precision measurement. [ABSTRACT FROM AUTHOR]

Quantitative measurements of atmospheric total OH reactivity (k OH ') provide crucial insights into atmospheric photochemistry. However, widespread application of total OH reactivity measurements is challenging due to insufficient equipment and the complexity of existing instrumentation. In this work, we report the development of a portable laser-flash photolysis Faraday rotation spectroscopy (LP-FRS) instrument for real-time and in-situ measurement of k OH '. To achieve efficient overlapping between the pump and probe laser and realize a long effective absorption path length, thus enabling high sensitivity measurement, a specific Herriott-type pump-probe optical multi-pass cell was designed with an overlapping factor of up to 75.4 %. The instrument's optical box dimensions were 130 cm × 40 cm × 35 cm. The obtained efficient absorption path was ~ 28.5 m in a base length of 77.2 cm. The k OH ' detection precisions of the LP-FRS instrument were 2.3 s-1 and 1.0 s-1 with averaging times of 60 s and 300 s, respectively. The k OH ' measurement uncertainty was evaluated to be within 2 s-1. Field measurement was performed, and the difference between the measured k OH ' and the model simulated from the measured reactive species was analysed. The developed portable LP-FRS instrument extends the measurement methods of atmospheric total OH reactivity, and has certain advantages in cost, operation, and transportation, which will play an increasingly important role in future atmospheric chemistry research. [ABSTRACT FROM AUTHOR]

In the current study, we attempt to remove 3‐monochloropropane‐1,2‐diol fatty acid ester (3‐MCPD ester) from palm oil with developed composite adsorbent (Tween80 modified activated carbon [AC]), and scanning electron microscopy‐energy dispersive spectrometer, Fourier transform‐infrared spectroscopy, X‐ray diffraction, nitrogen content adsorption‐desorption and thermogravimetric analysis were used to characterize the modifications. We further examined the adsorption capability of the composite adsorbent for 3‐MCPD ester and found that the highest removal efficiency was 87.36% (5.3% of adsorbent dose at 104°C for 29 min). This is approximately three times higher than that of pristine AC, implying that the composite can be employed as a novel adsorbent for 3‐MCPD ester reduction. Along with the adsorption mechanism of Langmuir, Freundlich, Dubinin–Radushkevich, and Temkin models were also tested. It has been suggested that Freundlich model could best describe the adsorption process. Adsorption was found to be well‐fitted by pseudo‐second‐order kinetics according to the kinetic study. An endothermic and spontaneous adsorption mechanism was demonstrated by the thermodynamic studies. [ABSTRACT FROM AUTHOR]

In this work, it is aimed to study the interplay of different longitudinal mode combs corresponding to higher‐order lateral modes of broad‐area Fabry–Pérot‐type laser diodes. Coherent coupling of longitudinal modes of different mode combs influences the near‐ and far‐field pattern of the diode. Herein, commercial state‐of‐the‐art high‐power laser diodes based on the (Al,In)GaN material system in the blue spectral range with a 40 μm broad ridge are investigated. To spectrally resolve the different lateral modes, a sequential combination of a high‐resolution double grating spectrometer and a Fabry–Pérot interferometer (FPI) is used. The grating spectrometer acts as bandpass with a spectral width smaller than the free spectral range (FSR) of the FPI. The FPI with a finesse of approximately F=60$ℱ = 60$ boosts the resolution to 0.08 pm. A spectral clustering of lateral modes with increasing current and also a variation of the number of distinguishable lateral modes between 7 and 11 are observed. Within the current range from 1.25Ith to 2.25Ith, there is no clear evidence for coherent coupling. It is concluded that mode‐pulling is not strong enough to coherently couple modes on the investigated time and wavelength range. [ABSTRACT FROM AUTHOR]

The design and first results of a high‐transmission soft X‐ray spectrometer operated at the X‐SPEC double‐undulator beamline of the KIT Light Source are presented. As a unique feature, particular emphasis was placed on optimizing the spectrometer transmission by maximizing the solid angle and the efficiencies of spectrometer gratings and detector. A CMOS detector, optimized for soft X‐rays, allows for quantum efficiencies of 90% or above over the full energy range of the spectrometer, while simultaneously offering short readout times. Combining an optimized control system at the X‐SPEC beamline with continuous energy scans (as opposed to step scans), the high transmission of the spectrometer, and the fast readout of the CMOS camera, enable the collection of entire rapid resonant inelastic soft X‐ray scattering maps in less than 1 min. Series of spectra at a fixed energy can be taken with a frequency of up to 5 Hz. Furthermore, the use of higher‐order reflections allows a very wide energy range (45 to 2000 eV) to be covered with only two blazed gratings, while keeping the efficiency high and the resolving power E/ΔE above 1500 and 3000 with low‐ and high‐energy gratings, respectively. [ABSTRACT FROM AUTHOR]

A compact and responsive thermoelectric photodetector is introduced for the mid‐infrared. By resonantly coupling mid‐infrared light to a Sb2Te3‐Bi2Te3 thermoelectric junction, a thermocouple is formed that is directly heated by narrow‐band mid‐infrared radiation. Near‐perfect absorption is achieved at this hot junction through the resonantly enhanced coupling of light to free‐electrons in the Bi2Te3 and Sb2Te3 materials. The fabricated devices operate at 3.6 µm and demonstrate a responsivity of 10.2 V W−1, a specific detectivity of 4.6 × 106 cm Hz1/2 W−1, and a bandwidth in the order of 1 kHz. The optimal detection wavelength can be spectrally tuned by changing the resonant cavity dimensions. This work shows a path toward miniaturized mid‐infrared detectors and spectrometers with high sensitivity, responsivity, and bandwidth. Importantly, the device presented here is ideal for industrial production, which it is hoped will provide wider access to mid‐infrared technologies for chemical sensing, medicine, and security. [ABSTRACT FROM AUTHOR]

We investigated neutron flux at a sample position and energy resolution of a direct-geometry disk-chopper spectrometer AMATERAS under various chopper conditions and compared them with simulations and calculations. The measured flux was comparable to that of similar high-flux spectrometers. The resolution when using a pulse-shaping chopper correlated well with the analytical calculations, including the thickness of the disk chopper, the sample size, and the penetration depth into the detector. The results show that the chopper, placed at the intermediate distance of the primary spectrometer, functions as a pulse shaper that optimizes the flux and resolution below the incident energy of 10 meV. [ABSTRACT FROM AUTHOR]

Hyperspectral imaging (HSI) finds broad applications in various fields due to its substantial optical signatures for the intrinsic identification of physical and chemical characteristics. However, it faces the inherent challenge of balancing spatial, temporal, and spectral resolution due to limited bandwidth. Here we present SpectraTrack, a computational HSI scheme that simultaneously achieves high spatial, temporal, and spectral resolution in the visible-to-near-infrared (VIS-NIR) spectral range. We deeply investigated the spatio-temporal-spectral multiplexing principle inherent in HSI videos. Based on this theoretical foundation, the SpectraTrack system uses two cameras including a line-scan imaging spectrometer for temporal-multiplexed hyperspectral data and an auxiliary RGB camera to capture motion flow. The motion flow guides hyperspectral reconstruction by reintegrating the scanned spectra into a 4D video. The SpectraTrack system can achieve around megapixel HSI at 100 fps with 1200 spectral channels, demonstrating its great application potential from drone-based anti-vibration video-rate HSI to high-throughput non-cooperative anti-spoofing. This work presents a computational hyperspectral imaging technique with high throughput, termed SpectraTrack. By deriving the spatio-temporal-spectral multiplexing principle, it achieved megapixel, hundred-fps, and thousand-channel spectral imaging. [ABSTRACT FROM AUTHOR]

Observations from space‐borne spectrometers have been lately used to quantify shipping emissions of nitrogen oxides (ΝΟΧ). Here we present a method that enhances the shipping signal of NO2 TROPOspheric MOnitoring Instrument (TROPOMI) satellite sensor observations in order to assess the impact of the Red Sea ship attacks on NO2 levels in three important shipping routes along the Red Sea, the Cape of Good Hope, and the Gibraltar Strait. Major shipping carriers, sailing usually via the Red Sea, have responded to the attacks by transiting their fleet around the African continent. The shipping signal from TROPOMI declines by ∼55% in the Red Sea and ∼15% in the Gibraltar Strait while an increase of ∼40% is found off the South African coast between January–June 2024 and the same period in 2023. These changes correlate well with vessel statistics, demonstrating the ability to track abrupt changes in NO2 shipping levels with satellite measurements. Plain Language Summary: Since the beginning of the Red Sea attacks on commercial vessels in late 2023, trade operations have been disrupted and international maritime routes have shifted away from the Red Sea. We use satellite measurements of atmospheric pollutants, capable of detecting emissions from ships along main trade routes, in order to examine the impact of the attacks along busy shipping lanes in the Red Sea, off the coast of South Africa and the Gibraltar Strait. Air pollution levels from ships show reductions of 55% and 15% in the Red Sea and Gibraltar areas, respectively, and an increase of 40% off the coast of South Africa, in the aftermath of the attacks. Changes in air pollution levels are well in line with changes in the number of ships transiting through these areas. Ship presence declined by approximately 55% and 15% in the Red Sea and the Gibraltar Strait, whereas it increased by 80% off the coast of South Africa. Both satellite observations and ship numbers verify quantitatively the re‐routing of ships away from the Red Sea through the coast of South Africa. Key Points: Red Sea ship attacks have shifted international maritime trade routesNO2 shipping levels decline by 55% in the Red Sea, 15% in the Gibraltar Strait, and increase by 40% off the coast of South AfricaNO2 shipping trends correspond to changes in the number of vessels [ABSTRACT FROM AUTHOR]

Pioneering the use of the Geostationary Environment Monitoring Spectrometer's (GEMS) observation data in air quality modeling, we adjusted Asia's NOx emissions inventory by leveraging the instrument's unprecedented sampling frequency. GEMS tropospheric NO2 columns served as top-down constraints, guiding our Bayesian inversion to constrain NOx emissions in Asia during spring 2022. This enabled the model to better capture the diurnal variation in NOx emissions, such as its morning rush hour peak, particularly when more retrievals were available each day, improving the simulation accuracy to a certain extent. The GEMS-informed adjustment reduced the extent of model underestimation of surface NO2 concentrations from 17.38 to 5.58% in Korea and from 13.05 to 4.54% in China, showing about 9.40% and 5.77% greater improvements, respectively, compared to the adjustment based on the sun-synchronous low earth orbit observation proxy. Our findings highlight the potential of geostationary observation data in refining the diurnal cycle of inventoried NOx emissions, thereby more effectively improving the accuracy of air quality simulations. [ABSTRACT FROM AUTHOR]

To clarify the transformation of the glassy and crystalline inclusions in cord steel during heat treatment, four groups of MnO–SiO2–Al2O3 systems with different MgO contents are designed to obtain samples with both glassy and crystalline inclusions by slow‐cooling, and then the samples are isothermal held at 1100 °C for 120 min. The results of X‐ray diffraction and scanning electron microscope and energy dispersive spectrometer indicate that after isothermal holding, the MgMnSiO4 crystalline phase transforms into MgAl2O4 and MnSiO3 phases in 5 wt% MgO system, while partial MgMnSiO4 phase transforms into MgSiO3 phase in 10 wt% MgO system. Besides, the MgMnSiO4 crystalline phase transforms into MgSiO3 and Mg2SiO4 phases in 15 wt% MgO system, while the Mg2SiO4 crystalline phase partially transforms into MgSiO3 phase in 20 wt% MgO system. Combined with the calculation results of FactSage 8.1, it shows that the higher the MgO content in the system, the stronger the crystallization ability and the easier the formation of the crystalline phase. During the isothermal holding process, the elements in inclusions continuously diffuse and migrate, so that the glassy phase transforms into crystalline phase, while the crystalline phase grows further and the internal glassy phase disappear, accompanied by the transformation of the crystal type. [ABSTRACT FROM AUTHOR]

On-chip spectrometers are increasingly becoming tools that might help in everyday life needs. The possibility offered by several available integration technologies and materials to be used to miniaturize spectrometers has led to a plethora of very different devices, that in principle can be compared according to their metrics. Having access to a reference database can help in selecting the best-performing on-chip spectrometers and being up to date in terms of standards and developments. In this paper, an overview of the most relevant publications available in the literature on miniaturized spectrometers is reported and a database is provided as an open-source project to which researchers can have access and participate in order to improve the share of knowledge in the interested scientific community. [ABSTRACT FROM AUTHOR]

The unique diffractive properties of gratings have made them essential in a wide range of applications, including spectral analysis, precision measurement, optical data storage, laser technology, and biomedical imaging. With advancements in micro- and nanotechnologies, the demand for more precise and efficient grating fabrication has increased. This review discusses the latest advancements in grating manufacturing techniques, particularly highlighting laser interference lithography, which excels in sub-beam generation through wavefront and amplitude division. Techniques such as Lloyd's mirror configurations produce stable interference fringe fields for grating patterning in a single exposure. Orthogonal and non-orthogonal, two-axis Lloyd's mirror interferometers have advanced the fabrication of two-dimensional gratings and large-area gratings, respectively, while laser interference combined with concave lenses enables the creation of concave gratings. Grating interferometry, utilizing optical interference principles, allows for highly precise measurements of minute displacements at the nanometer to sub-nanometer scale. This review also examines the application of grating interferometry in high-precision, absolute, and multi-degree-of-freedom measurement systems. Progress in grating fabrication has significantly advanced spectrometer technology, with integrated structures such as concave gratings, Fresnel gratings, and grating–microlens arrays driving the miniaturization of spectrometers and expanding their use in compact analytical instruments. [ABSTRACT FROM AUTHOR]

The standardized spectral mixture model combines the specificity of a physically based representation of a spectrally mixed pixel with the generality and portability of a spectral index. Earlier studies have used spectrally and geographically diverse collections of broadband and spectroscopic imagery to show that the reflectance of the majority of ice-free landscapes on Earth can be represented as linear mixtures of rock and soil substrates (S), photosynthetic vegetation (V) and dark targets (D) composed of shadow and spectrally absorptive/transmissive materials. However, both broadband and spectroscopic studies of the topology of spectral mixing spaces raise questions about the completeness and generality of the Substrate, Vegetation, Dark (SVD) model for imaging spectrometer data. This study uses a spectrally diverse collection of 40 granules from the EMIT imaging spectrometer to verify the generality and stability of the spectroscopic SVD model and characterize the SVD topology and plane of substrates to assess linearity of spectral mixing. New endmembers for soil and non-photosynthetic vegetation (NPV; N) allow the planar SVD model to be extended to a tetrahedral SVDN model to better accommodate the 3D topology of the mixing space. The SVDN model achieves smaller misfit than the SVD, but does so at the expense of implausible fractions beyond [0, 1]. However, a refined spectroscopic SVD model still achieves small (<0.03) RMS misfit, negligible sensitivity to endmember variability and strongly linear scaling over more than an order of magnitude range of spatial resolution. [ABSTRACT FROM AUTHOR]

This contribution illustrates the four different detector technologies used in the muon spectrometer of the Compact Muon Solenoid (CMS) experiment, installed on the Large Hadron Collider (LHC), and their future upgrades. These have the aim to cope with the scheduled increase of instantaneous luminosity of the LHC in the so-called High-Luminosity LHC phase. CMS Collab. [J. Instrum.3, S08004 (2008), https://doi.org/10.1088/1748-0221/3/08/S08004 ]. [ABSTRACT FROM AUTHOR]

The Mapping Imaging Spectrometer for Europa (MISE) is an infrared compositional instrument that will fly on NASA's Europa Clipper mission to the Jupiter system. MISE is designed to meet the Level-1 science requirements related to the mission's composition science objective to "understand the habitability of Europa's ocean through composition and chemistry" and to contribute to the geology science and ice shell and ocean objectives, thereby helping Europa Clipper achieve its mission goal to "explore Europa to investigate its habitability." MISE has a mass of 65 kg and uses an energy per flyby of 75.2 W-h. MISE will detect illumination from 0.8 to 5 μm with 10 nm spectral resolution, a spatial sampling of 25 m per pixel at 100 km altitude, and 300 cross-track pixels, enabling discrimination among the two principal states of water ice on Europa, identification of the main non-ice components of interest: salts, acids, and organics, and detection of trace materials as well as some thermal signatures. Furthermore, the spatial resolution and global coverage that MISE will achieve will be complemented by the higher spectral resolution of some Earth-based assets. MISE, combined with observations collected by the rest of the Europa Clipper payload, will enable significant advances in our understanding of how the large-scale structure of Europa's surface is shaped by geological processes and inform our understanding of the surface at microscale. This paper describes the planned MISE science investigations, instrument design, concept of operations, and data products. [ABSTRACT FROM AUTHOR]

The Hettrick–Underwood (HU) type design, consisting of a pre-focusing mirror and a varied-line-spacing planar grating (VLS-PG), for the high resolution resonant inelastic x-ray scattering spectrometer is considered. The light path of the HU design is analyzed, and the analytical functions determining the groove parameters of VLS-grating are given. Efforts are made to compare the different choices of the pre-focusing mirrors, circular cylindrical (HU-CM) and elliptical cylindrical (HU-EM). Although the HU-EM type offers great tuning properties with variable-included-angle, it imposes high requirement on the optical element manufacturing accuracy, while the HU-CM type design couples the coma contributions from the pre-mirror and the grating, allowing for mutual compensation of the manufacturing errors of the two optical elements. [ABSTRACT FROM AUTHOR]

Integrated computational spectrometers with gate‐tunable nano heterostructures and reconstruction algorithms are attractive for on‐chip gas‐sensing spectrometers and have enabled versatile spectrum detectors. However, they require the selective and optical filtering capabilities of wavelengths, restricting their efficient implementation in narrow‐band photodetection. In this study, a printable spectral phototransistor is developed with high dynamic detectivity (1012 Jones and 105 Hz at −3 db bandwidth) modulated by a GeS2 nanosheet heterostructure at short‐wave infrared (SWIR) regime. Using the transport mode switching of carriers in a heterostructure and the polarization‐sensitivity of the GeS2 two‐dimension (2‐D) nanosheet, this SWIR spectral phototransistor demonstrates an accurate narrow‐band selective (96.7% accuracy) spectrum detector and performed a deep‐learning analysis of an artificial neural network (ANN). Furthermore, this GeS2 2‐D based spectral phototransistor, characterized by its high in‐plane anisotropy and electrically reconfigurable properties, extends the applicability of narrow‐band photodetection with 15 nm Full Width at Half Maximum (FWHM) to the recognition of trace‐gases at the parts per billion (ppb) level. [ABSTRACT FROM AUTHOR]

Copyright of China Pulp & Paper is the property of China Pulp & Paper Magazines Publisher and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this study, we report highly precise and accurate measurements of the P(5), P(6), and O(3) transitions of the 2-0 band of HD occurring at approximately 1.5 µm. HD spectra were acquired in the pressure range of 100-900 Torr using a cavity ring-down spectrometer linked to an optical frequency comb. The line-shape analysis was performed using the Hartmann-Tran profile in the so-called β-corrected version. For the P(5) transition, we improved the accuracy of previous line center frequency determinations by more than two orders of magnitude. Moreover, for the P(5) and P(6) line centers, the total standard uncertainty is below 3 MHz, similar to those provided by quantum electrodynamics predictions, making them useful for direct comparisons that might foster future improvements of the theoretical model. [ABSTRACT FROM AUTHOR]

Accurate estimation of nitrogen dioxide (NO2) levels at high spatio‐temporal resolution is crucial for atmospheric research and public health assessments. This study introduces a novel machine learning (ML) framework enhanced with uncertainty quantification (UQ) to predict hourly NO2 concentrations over East Asia. Benefiting from tropospheric NO2 columns from the Geostationary Environment Monitoring Spectrometer (GEMS), along with land use, meteorological, and topographic data, our model demonstrates robust and reliable performance, evidenced by an R2 of 0.84 and RMSE of 2.93 ppb through cross‐validation. Unlike traditional ML regressions tasks, our framework not only provides a single NO2 estimate but also diagnoses data and model uncertainties for each pixel. Higher uncertainties are observed in regions with complex terrain and sparse monitoring. Hourly and Intra‐annual variations in concentration predictions and associated uncertainties are both significant. The explicit UQ informs decision‐making and highlights the need for cautious interpretation in atmospheric data‐driven predictions. Plain Language Summary: Our study aims to improve understanding of near‐surface nitrogen dioxide (NO2) levels, crucial for accessing health risks. Machine learning (ML) has emerged as a powerful tool in converting satellite‐derived NO2 columns to near‐surface concentrations. However, previous estimates were based on polar‐orbiting satellites, which yield only a single daily result. In contrast, we use data products from the Geostationary Environment Monitoring Spectrometer (GEMS), the first sensor providing continuous monitoring over Asia with hourly updates on NO2 columns during daylight. Importantly, while these ML models proficiently predict NO2 levels at the stations, they tend to lack a comprehensive uncertainty assessment, leading to potential overreliance on their spatial performance. Our work developed a way to not only capture hourly variations of near‐surface NO2 concentrations but also to quantify the certainty about these estimates across the entire space. This enhances air quality decision‐making and underscores the need for careful environmental prediction analysis. Key Points: Quantify data and model uncertainties in machine learning, revealing data surpasses model—critical for accurate assessmentsDerive hourly NO2 concentrations from GEMS NO2 columns, refining spatial‐temporal resolutionInform site construction decisions, cautioning against overestimating machine learning's spatial generalization capabilities [ABSTRACT FROM AUTHOR]

ABSTRACT In relation to debates in the recent literature on the utility and robustness of adventitious carbon for charge correction of X‐ray photoelectron spectra, the present work explores its application using 5 years' worth of data collected by the author. The data overwhelmingly show that regardless of spectrometer or charge compensation method, and but for a few exceptions where a secondary reference is preferrable, a C 1s value of 284.8 eV is suitable for electronically isolated samples. [ABSTRACT FROM AUTHOR]

This study focuses on the comparative analysis and research of the raindrop size distribution (DSD) in the outer rainband and inner rainband of Typhoon "Noru" in 2022, using the OTT-Parsivel raindrop spectrometer deployed on Yongxing Island, Sansha City. The results indicate that precipitation intensity is lower when composed mainly of small and medium raindrops and increases with the presence of larger raindrops. Stronger precipitation is associated with a higher number of large raindrops. Due to the interaction of cold and warm air masses, the raindrop concentration is higher, and the raindrop diameters are larger compared to Typhoons "LEKIMA" and "RUMBIA". The entire process predominantly consists of numerous small- to medium-sized raindrops, characteristic of a tropical typhoon. The precipitation in the inner and outer rainbands exhibits consistent types, characterized by a unimodal raindrop size distribution with a narrow spectral width, typical of stratiform-mixed cloud precipitation, where stratiform precipitation constitutes a significant portion. Strong echo reflectivity factors are often associated with higher raindrop number concentrations and larger particle sizes. The Z-R relationship of the precipitation shows a smaller coefficient but a consistent exponent compared to the standard. The calculated shape parameter slope relationship is Λ = 0.02 μ 2 + 0.696 μ + 1.539 , providing a reference for localizing the Z-R relationship in the South China Sea. [ABSTRACT FROM AUTHOR]

True ternary fission, the fission of a nucleus into three fragments of nearly equal mass, is an elusive and poorly known process influenced by shell effects. An increase in the probability of this process with respect to binary fission, which is very low in spontaneous and neutron-induced fission, has been envisaged. Heavy-ion-induced reactions are adopted due to the possibility of an increase in the fissility parameter and the excitation energy of the compound nuclei. Nuclei with mass number around A = 250, accessible in heavy-ion-induced reactions, are favorable and should be investigated. It is still debated if the process takes place in a single step, direct ternary fission, or in a two step, sequential ternary fission. The purpose of this work is to define experimental conditions and observables that allow the disentangling of the products from the direct and sequential ternary fission, as well as from the usual most probable binary fission. This step is essential for gaining insights into the ternary fission dynamics and the binary to ternary fission competition. The method proposed here is for simulating the kinematics of the ternary and binary fission processes to compute the energy distributions and angular correlations of direct and sequential ternary fission products, as well as those of binary fission. The reaction taken as a benchmark is 40Ar + 208Pb at 230 MeV and is supposed to form the 248Fm* compound nucleus. The simulation results have been filtered by considering the response function of a multi-coincidence detection system virtually constructed using the Geant4 simulation toolkit. The simulations support the possibility of separating the products of different multimodal fission decays with the proposed setup that consequently represents an effective tool to obtain insights into ternary fission from the observables selected. [ABSTRACT FROM AUTHOR]

Sensitive mid‐infrared (MIR) spectroscopy plays an indispensable role in various photon‐starved conditions. However, the detection sensitivity of conventional MIR spectrometers is severely limited by excessive noises of the involved infrared sensors, especially for multi‐pixel arrays in parallel spectral acquisition. Here, an ultra‐sensitive MIR single‐pixel spectrometer is devised and implemented, which relies on high‐fidelity spectral upconversion and wavelength‐encoding compressive measurement. Specifically, a MIR nanophotonic supercontinuum from 3.1 to 3.9 µm is nonlinearly converted to the NIR band via synchronous chirped‐pulse pumping, which facilitates both the precise spectral mapping and sensitive upconversion detection. The upconverted signal is then spatially dispersed onto a programmable digital micromirror device, before being registered by a single‐element silicon detector. Consequently, the spectral information can be deciphered from the correlation between encoded patterns and recorded measurements, which results in a spectral resolution of 0.5 cm−1${\rm cm}^{-1}$ under an illumination flux down to 0.01 photons nm–1 pulse–1. Moreover, faithful reconstructions at sub‐Nyquist sampling rates are demonstrated using the compressive sensing algorithm, which leads to a 95% reduction in data acquisition time. The presented single‐pixel computational spectrometer features wavelength multiplexing, high throughput, and efficient sampling, which thus paves a new way for sensitive and fast spectroscopic analysis at the single‐photon level. [ABSTRACT FROM AUTHOR]

Here we present measurements of dissociative and non-dissociative cross-sections for the electron impact of the CF4 molecule. The present experiments are based on a Recoil Ion Momentum Spectrometer (RIMS), a standard gas mixing setup for CF4, and a reference gas. The measurements were carried out at several electron energies up to 1 keV, covering the energy range of previous experiments. We apply the relative flow technique (RFT) to convert the relative cross-sections measured by the RIMS into absolute values. Using the combination of RIMS and RFT, ion collection and calibration errors were minimized. The results were compared with theoretical and experimental studies available in the literature. Previous electron impact experiments present relative cross-sections or use correction terms for the absolute cross-sections due to losses of energetic ions. We elucidate the differences between the new measurement method and the existing ones in the literature and explain why the present method can be considered reliable. Furthermore, we show how reducing correction terms affects the results. [ABSTRACT FROM AUTHOR]

Here, we present the design and first calibration results of a new single-channel Fast-Ion D-Alpha (FIDA) spectrometer to be employed at the National Spherical Torus Experiment Upgrade (NSTX-U). The Czerny–Turner-type spectrometer uses a custom-designed aspherical lens setup instead of mirrors and achieves excellent spectral resolution, with high photon throughput through a round-to-linear fiber bundle, and camera frame rates around 8.4 kHz. The spectrometer uses a blocking bar to avoid saturation effects of the cold D-alpha emission line and will allow for detailed studies of the fast-ion confinement in NSTX-U. Expected synthetic spectra predicted with the TRANSP and FIDASIM codes show that the spectral range from 648.5 to 658 nm will sufficiently cover halo, the red-shifted beam emission, and the blue-shifted portion of FIDA emission in NSTX-U, which is sufficient for fast-ion transport studies of co-rotating fast ions. [ABSTRACT FROM AUTHOR]

Blueberries offer multiple health benefits, and their cultivation has expanded to warm tropical regions. However, references for foliar nutritional content are lacking in the literature. Proximal sensing may enhance nutritional characterization to optimize blueberry production. We aimed (i) to characterize the nutrient contents of healthy plants of three blueberry varieties adapted to warm climates (Emerald, Jewel, and Biloxi) using a reference method for foliar analysis (inductively coupled plasma (ICP)) and a portable X-ray fluorescence (pXRF) spectrometer on fresh and dry leaves and (ii) to differentiate blueberry varieties based on their nutrient composition. Nutrient content was statistically compared per leaf moisture condition (fresh or dry) with ICP results and used to differentiate the varieties via the random forest algorithm. P and Zn contents (ICP) in leaves were different among varieties. Dry leaf results (pXRF) were strongly correlated with ICP results. Most nutrients determined using ICP presented good correlation with pXRF data (R2 from 0.66 to 0.93). The three varieties were accurately differentiated by pXRF results (accuracy: 87%; kappa: 0.80). Predictions of nutrient contents based on dry leaves analyzed by pXRF outperformed those based on fresh leaves. This approach can also be applied to other crops to facilitate nutrient assessment in leaves. [ABSTRACT FROM AUTHOR]

This study presents advancements in the processing of satellite remote sensing data, focusing mainly on aerosol optical depth (AOD) retrievals from the Geostationary Environment Monitoring Spectrometer (GEMS). The transformation of Level-2 (L2) data, which includes atmospheric-state retrievals, into higher-quality Level-3 (L3) data is crucial in remote sensing. Our contributions lie in two novel improvements to the processing algorithm. First, we improve the inverse-distance-weighting algorithm by incorporating quality flag information into the weight calculation. By assigning weights that are inversely proportional to the number of unreliable grids, the method can provide more accurate L3 products. We validate this approach through simulation studies and apply it to GEMS AOD data across various regions and wavelengths. The use of quality flags in the algorithm can provide a more accurate analysis of remote sensing. Second, we employ a spatiotemporal merging method to address both spatial and temporal variability in AOD data, a departure from previous approaches that solely focused on spatial variability. Our method considers temporal variations spanning previous time intervals. Furthermore, the computed mean fields show similar spatiotemporal patterns to previous studies, confirming their ability to capture real-world phenomena. Lastly, utilizing this procedure, we compute the mean field estimates for GEMS AOD data, which can provide a deeper understanding of the impact of aerosols on climate change and public health. [ABSTRACT FROM AUTHOR]

A 1D imaging soft X‐ray spectrometer installed on the small quantum systems (SQS) scientific instrument of the European XFEL is described. It uses movable cylindrical constant‐line‐spacing gratings in the Rowland configuration for energy dispersion in the vertical plane, and Wolter optics for simultaneous 1D imaging of the source in the horizontal plane. The soft X‐ray fluorescence spectro‐imaging capability will be exploited in pump–probe measurements and in investigations of propagation effects and other nonlinear phenomena. [ABSTRACT FROM AUTHOR]

A broadband online X‐ray spectrometer has been designed and commissioned at the SUD beamline of the Shanghai Soft X‐ray Free‐Electron Laser Facility, which can deliver both SASE and seeded FEL pulses to user experiments, spanning the photon energy range of 50–620 eV. The resolving powers of the spectrometer calibrated via online measurement at 92 eV and 249 eV are ∼20000 and ∼15000, respectively, and the absolute photon energy is characterized by an electron time‐of‐flight spectrometer. The high energy resolution provided by the spectrometer can differentiate the fine structure in the FEL spectrum, to determine its pulse length. [ABSTRACT FROM AUTHOR]

Improving the spectral signal-to-noise ratio is crucial for obtaining high-quality Raman spectra of target substances. To achieve a higher instrument signal-to-noise ratio in the development of spatial heterodyne Raman spectrometer, the effect of spatially compressed illumination on the spectral signal-to-noise ratio was theoretically analyzed. A spatial heterodyne Raman spectroscopic experimental setup with compressed illumination was constructed. The experimental results with ethanol validate the significant enhancement of the signal-to-noise ratio achieved through compressed illumination. The ethanol spectra exhibited signal-to-noise ratio enhancements ranging from 1.38 to 7.98 times under various excitation powers and integration times. These findings provide valuable guidance for further improving the performance of spatial heterodyne Raman spectrometers. [ABSTRACT FROM AUTHOR]

The paper proposes a wave spectral partitioning method for the surface waves investigation and monitoring (SWIM) spectrometer based on the wave age and parameter optimization (WA-PO) method. The wave age criterion is a way to identify waves as wind waves or swells, and parameter optimization methods enable the modeling of wave spectra. The combination of the two can use the spectrum models to fit the SWIM spectra based on clarifying whether the spectrum models belong to wind waves or swells, which achieves spectral partitioning. The WA-PO method consists of four steps: peaks region dividing, spectral peaks searching, objective function constructing, and model parameters optimizing. The results show that compared with the partition products provided by the SWIM, the partition parameters obtained from the WA-PO method are closer to those of the Integrated Ocean Waves for Geophysical and other Applications (IOWAGA) numerical hindcast dataset developed from the WAVEWATCH III (WW3). The WA-PO method can prevent over-partitioning of the wave spectra and detect wind-wave components hidden in the swell partition. [ABSTRACT FROM AUTHOR]

Spatial heterodyne Raman spectroscopy has been widely applied in various fields due to its non-contact, nondestructive, fast, high stability, and high spectral resolution characteristics. This article integrated spatial heterodyne Raman spectroscopy with chemometric methodologies to assess the feasibility of peak-to-peak ratio regression, partial least squares regression, support vector machine regression, and non-negative matrix factorization for the quantitative analysis of mixtures. Chemometrics methods were used to model and analyze the interference data in the interferogram domain, and variational mode decomposition was used to extract features from the interference data, further improving the interference data's modeling and prediction accuracy. The results demonstrate that modal intensities obtained through variational mode decomposition of interference data improve the prediction accuracy of regression analysis. Support vector regression exhibited the most favorable predictive performance among the tested models. The root mean square error of cross-validation was reduced from 5.55% to 2.64%, and the prediction root mean square error was reduced from 5.08% to 1.5%. The improved model utilizing interference data showed higher fitting accuracy and more precise sample predictions compared to spectral data modeling. [ABSTRACT FROM AUTHOR]

We performed a measurement of the inclusive missing-mass spectrum of the |$^{12}$| C |$(K^-, K^+)$| reaction at an incident beam momentum of 1.8 GeV/ c. This measurement was carried out by using the Superconducting Kaon Spectrometer (SKS) and the K1.8 beamline spectrometer at the Hadron Experimental Facility in J-PARC. From the missing-mass of the |$^{12}$| C |$(K^-, K^+)$| reaction, the binding energy of a |$\Xi ^-$| hyperon in a core |$^{11}$| B nucleus, |$B_{\Xi ^-}$|⁠ , can be calculated. Our experimental setup yielded a good energy resolution of 8.2 MeV (full width at half maximum), which allowed us to observe significant enhancements in the proximity of the |$^{12}_{\Xi }$| Be production threshold region. In order to extract information from the missing-mass spectrum, we employed several fitting parameters assumptions. A good agreement with the spectrum shape was obtained by adding two Gaussian functions, with the constant experimental resolution for the |$\Xi$| -hypernuclear states, to the background distribution. The peak positions were obtained to be |$B_{\Xi ^-} = 8.9 \pm 1.4$| (stat.) |$^{+3.8}_{-3.1}$| (syst.) MeV and |$B_{\Xi ^-} = -2.4 \pm 1.3$| (stat.) |$^{+2.8}_{-1.2}$| (syst.) MeV. Another model assumption, one Breit–Wigner function with |$B_{\Xi ^-} = -2.7 \pm 2.2$| (stat.) |$^{+0.5}_{-0.7}$| (syst.) MeV and |$\Gamma = 4.1 \pm 2.1$| (stat.) |$^{+1.2}_{-0.7}$| (syst.) MeV, also yielded a similar |$\chi ^2$| value. [ABSTRACT FROM AUTHOR]

Using gamma and alpha spectrometers, the radioactive isotopes 226Ra, 210Pb, 232Th, and 40K were determined in three sediment cores from the Tam Giang-Cau Hai (TG), Thi Nai (TN), and Nai (DN) lagoons, and radiation risk indices were computed. The radioactivity concentrations of 210Pb, 40K, 232Th, and 226Ra were 55.46 Bq/kg, 675.78 Bq/kg, 67.22 Bq/kg, and 34.15 Bq/kg, respectively. The Raeq, ADR, AEDE, Iγr, AUI, Hex, and AGDE indices were 182.31 Bq/kg, 84.46 nGy/h, 0.10 mSV/y, 1.35, 1, 18, 0.49, and 598.71 µSV/y, respectively; the values of 40K, 232Th, AEDE, ADR, Iγr, and AGDE were greater than the global average and UNSCEAR values. The radioactivity and radiation risk indices decreased in the order DN > TN > TG. [ABSTRACT FROM AUTHOR]

Integrated miniature spectrometers have impacts in industry, agriculture, and aerospace applications due to their unique advantages in portability and energy consumption. Although existing on-chip spectrometers have achieved breakthroughs in key performance metrics, such as, a high resolution and a large bandwidth, their scanning speed and energy consumption still hinder practical applications of such devices. Here, a stationary Fourier transform spectrometer is introduced based on a Mach–Zehnder interferometer structure on thin-film lithium niobate. Long and low-loss spiral waveguides with electro-optic tuning are adopted as the optical path scanning elements with a half-wave voltage of 0.14 V. A high resolution of 2.1 nm and a spectral recovery with a bandwidth of 100 nm is demonstrated under a high-speed and high-voltage scanning in the range of −100 V to +100 V at up to 100 KHz. A low energy consumption in the μJ scale per scan is also achieved. [ABSTRACT FROM AUTHOR]

Optical spectrum analysis provides a wealth of information about the physical world. Throughout the development of optical spectrum analysis, sensitivity has been one of the major topics and has become essential in applications dealing with faint light. Various high-sensitivity optical detection technologies have been applied in optical spectrum analysis to enhance its sensitivity to single-photon level. As an emerging single-photon detection technology, superconducting nanowire single-photon detectors (SNSPDs) have many impressive features such as high detection efficiency, broad operation bandwidth, small timing jitter, and so on, which make them promising for enhancing the performance of optical spectral analysis. Diverse schemes for photon-counting spectrometers based on SNSPDs have been demonstrated. This article reviews these impressive works and prospects for the future development of this technology. Further breakthroughs can be expected in its theories, device performance, applications, and combinations with in-sensor computing, promoting it to be a mature and versatile solution for optical spectrum analysis on ultra-faint light.

Intensities of 14 lines in the sixth overtone (7–0) band of carbon monoxide (12C16O) are measured in the visible range between 14 300 and 14 500 cm−1 using a frequency-stabilized cavity ring-down spectrometer. This is the first observation of such a high and weak overtone spectrum of the CO molecule. A theoretical model is constructed and tested based on the use of a high accuracy ab initio dipole moment curve and a semi-empirical potential energy curve. Accurate studies of high overtone transitions provide a challenge to both experiment and theory as the lines are very weak: below 2 × 10−29 cm molecule−1 at 296 K. Agreement between theory and experiment within the experimental uncertainty of a few percent is obtained. However, this agreement is only achieved after issues with the stability of the Davidson correction to the multi-reference configuration interaction calculations are addressed. [ABSTRACT FROM AUTHOR]

Continuous observation of solar radio bursts (SRBs) throughout the year using the CALLISTO spectrometer generates a huge volume of spectral data. This study introduces a burst-classifier algorithm, which is an automated algorithm, to classify the SRB spectrum into three solar radio bursts, namely Type II (SRBT II), Type III (SRBT III) and Type IV (SRBT IV). The proposed algorithm was designed using four characteristic parameters derived from a collection of training dataset files. The characteristic parameters were derived from the intensity bursts observed on frequency channels and timesteps of the spectrum. This dataset consisted of 50 spectra of SRBT II and SRBT III, along with 40 spectra for SRBT IV, collected during the solar maximum of 2014 (Solar Cycle 24). After observations and analysis of the training dataset, each burst type was set up with a threshold. A training dataset of 80 data spectra from 2013 to 2016 was used to test the algorithm. Accuracy of the proposed algorithm was calculated using the percentage of true positives (TP) and false positives (FP). Findings demonstrate an accuracy of ∼74 % with 57 out of 80 spectra classified as TP and 23 spectra as FP. [ABSTRACT FROM AUTHOR]

Rationale: Dual clumped isotope paleothermometry determines carbonate formation temperatures by measuring the frequency of 13C–18O (∆638) and 18O–18O (∆828) pairs in carbonates. It resolves isotopic kinetic biases and thus enables more accurate paleotemperature reconstructions. However, high‐precision measurements of 18O–18O clumping using current techniques requires large sample sizes and long acquisition times. Methods: We developed a mid‐infrared isotope ratio laser spectrometer (IRLS) for simultaneous measurement of the isotopologue ratios ∆638 and ∆828 in gas‐phase carbon dioxide (CO2) at room temperature. Our IRLS uses a single laser scanning from 2290.7 to 2291.1 cm−1 and a 31 m pathlength optical cell, and it simultaneously measures the five isotopologues required for calculating ∆638 and ∆828: 16O12C16O, 16O13C16O, 16O12C18O, 16O13C18O, and 18O12C18O. In addition, our IRLS can measure 16O12C17O, enabling ∆17O analysis. Results: At ~20°C and a CO2 pressure of ~2 Torr, our IRLS system achieved precisions of 0.128‰ and 0.140‰ within 20 s for abundances of the clumped isotopologues 16O13C18O and 18O12C18O, respectively, and precisions of 0.267‰, 0.245‰, and 0.128‰ for 16O12C16O, 16O13C16O, and 16O12C18O. This yielded precisions of 0.348‰ (∆638) and 0.302‰ (∆828) within 25 s. Simulated sample–reference switching highlights the potential of our system and the need for further development. Conclusions: We demonstrated simultaneous measurements of ∆638 and ∆828 in CO2 to precisions of <0.35‰ within 25 s using a room‐temperature, single‐laser IRLS. Future developments on better resolving 16O12C16O and 16O13C16O peaks and system temperature control could further improve the measurement precision. [ABSTRACT FROM AUTHOR]

Rationale: Signal detection for uranium–lead (U–Pb) dating of zircon is typically performed via ion counters. Here, we develop a preliminary understanding of the strengths and limitations of faraday‐cup‐based detection. Methods: A suite of zircon reference materials and the NIST‐610 glass were sampled using laser ablation followed by U–Pb isotope ratio measurement on a Neoma multicollector‐inductively coupled plasma‐mass spectrometer. Results: We were able to produce geologically accurate 207Pb/206Pb, 206Pb/238U, and 207Pb/235U ratios for the NIST‐610 glass and the zircon standards, with ages ranging from ~2.5 Ga to ~337 Ma (TanBrown A, Oracle, 91550, Mud Tank, Temora, and Plešovice). Two of the younger zircon standards examined (94‐35, ~55.6 Ma, and Fish Canyon, 28.6 Ma) yielded accurate 206Pb/238U but not 207Pb/235U or 207Pb/206Pb ratios, whereas the youngest zircon standard (Penglai, ~4.4 Ma) failed for all three ratios of interest. The accuracy and precision of the all‐faraday method are directly tied to signal intensity, with reliable data capable of being produced even when both isotopes in a ratio have signals below ~0.001 V (equivalent to ~62 500 cps on an ion counter). Conclusion: The all‐faraday cup multicollection method provides sufficient sensitivity to obtain geologically meaningful U–Pb data, with possible advantages being that laser pit depth‐dependent changes in the observed interelemental fractionation behavior may be easier to correct using a static collector configuration compared to when the ion beam is swept across a single detector while also removing the need for an interdetector‐type calibration. Further work is needed to refine the all‐faraday cup method (e.g., application of background subtraction and common Pb corrections, outlier removal, and interelement as well as down‐hole fractionation corrections), but our initial results demonstrate that the faraday detector method has sufficient sensitivity to warrant further study. [ABSTRACT FROM AUTHOR]

Rationale: Dual clumped isotope paleothermometry determines carbonate formation temperatures by measuring the frequency of 13C–18O (∆638) and 18O–18O (∆828) pairs in carbonates. It resolves isotopic kinetic biases and thus enables more accurate paleotemperature reconstructions. However, high‐precision measurements of 18O–18O clumping using current techniques requires large sample sizes and long acquisition times. Methods: We developed a mid‐infrared isotope ratio laser spectrometer (IRLS) for simultaneous measurement of the isotopologue ratios ∆638 and ∆828 in gas‐phase carbon dioxide (CO2) at room temperature. Our IRLS uses a single laser scanning from 2290.7 to 2291.1 cm−1 and a 31 m pathlength optical cell, and it simultaneously measures the five isotopologues required for calculating ∆638 and ∆828: 16O12C16O, 16O13C16O, 16O12C18O, 16O13C18O, and 18O12C18O. In addition, our IRLS can measure 16O12C17O, enabling ∆17O analysis. Results: At ~20°C and a CO2 pressure of ~2 Torr, our IRLS system achieved precisions of 0.128‰ and 0.140‰ within 20 s for abundances of the clumped isotopologues 16O13C18O and 18O12C18O, respectively, and precisions of 0.267‰, 0.245‰, and 0.128‰ for 16O12C16O, 16O13C16O, and 16O12C18O. This yielded precisions of 0.348‰ (∆638) and 0.302‰ (∆828) within 25 s. Simulated sample–reference switching highlights the potential of our system and the need for further development. Conclusions: We demonstrated simultaneous measurements of ∆638 and ∆828 in CO2 to precisions of <0.35‰ within 25 s using a room‐temperature, single‐laser IRLS. Future developments on better resolving 16O12C16O and 16O13C16O peaks and system temperature control could further improve the measurement precision. [ABSTRACT FROM AUTHOR]

A multi‐object silicon photonic spectrometer with N input ports is proposed and realized by integrating a multi‐channel passband optical filter (POF), a tunable narrow‐band optical filter as well as a calibration‐free N × 1 Mach–Zehnder switch (MZS) array. Here, the multi‐channel POF consisting of a multimode waveguide grating (MWG) and a mode (de)multiplexer is used to achieve a broadened working window and an enhanced dynamic range for the present spectrometer, while the narrow‐band optical filter is realized with a thermally‐tunable Euler micro‐ring resonator (EMR) for achieving a very high spectral resolution. The introduction of the N × 1 MZS enables the time‐division‐multiplexed (TDM) spectrum analysis for multiple objects. In this paper, a multi‐object silicon photonic spectrometer with 16 input ports is demonstrated with an on‐chip loss of less than 3 dB and inter‐channel crosstalk as low as −25 dB. This multi‐object spectrometer can be used to analyze the spectra of 16 objects one by one by setting the 16 × 1 MZS, the resolution is as high as 50 pm, and the working window is ≈84 nm. [ABSTRACT FROM AUTHOR]