Emission Spectra Research Articles

Spatiotemporal Characteristics of Carbon Emissions from Construction Land and Their Decoupling Effects in the Yellow River Basin, China

Carbon emissions (CE) from expanding construction land (CL), a vital territory for human production and habitation, have contributed to climate change worldwide. The Yellow River Basin (YRB), an essential economic region and energy supply base in China, is experiencing rapid urbanization, and the contradiction between economic development and ecological protection is increasingly acute. Consequently, a thorough examination of the spatial and temporal change features of carbon emissions from construction land (CECL) and its decoupling from economic growth (EG) is crucial for the maintaining development of the region. This study adopts the IPCC carbon emission coefficient approach for measuring the CECL in the YRB from 2010 to 2021. The temporal and spatial variation features of CECL in the YRB were revealed using ArcGIS software and the standard deviation ellipse (SDE) model. The decoupling effect between CECL and EG was analyzed using the Tapio decoupling model and innovatively combined with the Logarithmic Mean Divisia Index (LMDI) method to explore the influence of five main drivers on the decoupling effect. This study found that: (1) The CECL rose from 2.463 billion tons in 2010 to 3.329 billion tons in 2021. The spatial layout of CECL is “high in the east and low in the west”. (2) The SDE of CECL is distributed in the direction of “northeast to southwest”, and the gravity center’s moving path is “northwest to northeast to northwest”; (3) weak decoupling (WD) is the main decoupling state between CECL and EG; (4) the economic output effect and the construction land (CL) scale effect are the two main factors inhibiting the decoupling of CECL, while the energy intensity effect, the population density effect, and the energy structure effect are the main elements motivating the decoupling of CECL. This study provides specific references and bases for the YRB in China and other countries and regions with similar levels of development in promoting green and ecologically friendly initiatives and achieving low-carbon utilization of regional land and sustainable development.

AIMD-Based Protocols for Modeling Exciplex Fluorescence Spectra and Inter-System Crossing in Photocatalytic Chromophores.

This study introduces a computational protocol for modeling the emission spectra of exciplexes using excited-state abinitio molecular dynamics (AIMD) simulations. The protocol is applied to a model exciplex formed by oligo-p-phenylenes (OPPs) and triethylamine (TEA), which is of interest in the context of photocatalytic reduction of . AIMD facilitates efficient sampling of the conformational space of OPP3 and OPP4 exciplexes with TEA, offering a dynamic alternative to previously employed static methods. The AIMD-based protocol successfully reproduces experimental emission spectra for OPP-TEA exciplexes, agreeing with previous computational and experimental findings. The results show that AIMD simulations provide an efficient means of sampling the conformational space of these exciplexes, requiring less user input and, in some instances, fewer computational resources than multiple excited-state optimizations initiated from user-specified initial structures. The study also evaluates the yield of intersystem crossing (ISC) using AIMD and Landau-Zener probability. The results suggest that ISC is a minor decay channel for OPP3 and OPP4. This work provides new insights into the structural flexibility and emission characteristics of OPP-TEA photoredox catalyst systems, potentially contributing to improved design strategies for organic chromophores in reduction applications.

Laser-Induced Breakdown Spectroscopy Using 2D Structured Light: A Case of Spectral Signal Enhancement on Metal Samples.

Laser-induced breakdown spectroscopy (LIBS), an elemental detection technique with great potential, faces many problems mainly caused by the nonideal plasma properties in the detection window. The 2D laser energy distribution on the sample surface has a crucial impact on the plasma properties and spectral emission. However, relevant studies are still limited, lacking a good degree of freedom (DOF) to systematically explore its influence. In this work, 2D structured light was generated by using a spatial light modulator (SLM). Various focal patterns with different cross-section areas were tested using metal samples so that the effects of the focal spot structure and cross-section area could be separated. The arrow-target and anticone of 200 μm diameter resulted in a line enhancement factor of more than 3 for a pure aluminum sample and a factor of about 6 for the pure copper sample over that without beam modulation. A significant improvement in the signal-to-noise ratio and a reduction in the limit of detection (LOD) of Cr, Mn, Si, Cu, and Al by a factor of about 6 were also achieved with the bearing steel sample. To better understand the mechanism behind such improvements, time-resolved spectra were measured, from which the electron density and plasma temperature evolution were calculated. The results showed that with anticone and arrow-target patterns, the electron density was increased by more than 50%, while the plasma temperature varied less than 500 K, suggesting an evident ablation enhancement. The fast images of plasma self-emission proved that the laser energy distribution substantially influenced the morphology of the plasma plume. The plasma cores produced by the anticone and arrow-target focal patterns were more compact after the expansion and cooling process, which could reduce the mixing of plasma plumes and ambient air. Thus, with the first application of SLM in LIBS, focal spot structures of micrometer resolution could be rationally designed and generated with a high DOF. Substantial spectral signal enhancement and a much lower LOD were achieved. This study provides new insights into the role of focal patterns in plasma properties, suggesting the future possibility of plasma control using structured light.

Ultrabroadband near-infrared emission profiling in multicore optical fibers doped with Er3+ and Yb3+/Tm3+/Ho3+ ions.

This paper presents novel multicore fibers with broadband emission in the 1.4-2.1μm range. Based on our previous work with barium gallo-germanate glasses and fibers, the 4 and 11-core fiber structures, each containing core glasses doped with Er3+ and Yb3+/Tm3+/Ho3+, were developed. Our efforts have resulted in flat emission in 3 dB and 10 dB bands, achievable under excitation at 796nm, 808nm, 940nm, and 980nm. The measured emission spectra of these fibers are described as a superposition of emission bands from each individual core, corresponding to the transitions of Er3+, Tm3+, and Ho3+ ions. Our method demonstrates the potential of emission profiling in multicore optical fibers as a new way to construct eye-safe broadband fiber sources.

Carbonyl-nitrogen multi-resonance emitters for efficient OLEDs with high color purity

Multi-resonance (MR) materials hold an intriguing feature of narrow emission spectra and have attracted considerable attention in the manufacture of high-definition organic light-emitting diodes (OLEDs). However, the majority of MR materials are composed by a boron-nitrogen skeleton, which is unfavorable for expanding the scope of luminescent materials with narrow emission spectra to meet various application demands. In this work, we wish to report a new carbonyl-nitrogen (C = O/N) skeleton of 5,12-dihydroquinolino[2,3-b]acridine-7,14-dione (QA), and three tailored C = O/N MR molecules are synthesized and fully characterized by crystallography, thermal measurement, cyclic voltammetry, steady-state and transient spectroscopy and theoretical calculation. They show efficient green emissions with narrow full width at half maximum (FWHM) of about 27 nm and high photoluminescence quantum yields of up to 93% in doped films. Efficient hyperfluorescence OLEDs are fabricated using these materials as emitters, providing pure green lights with electroluminescence peaks at 526‒538 nm, narrow FWHMs of 29‒33 nm, excellent external quantum efficiencies of up to 29.48% and small efficiency roll-offs. These results reveal that QA could be a potential skeleton for exploring efficient C = O/N MR molecules.

Dispersion effects in thermal emission from temporal metamaterials: high-frequency cutoffs

The latest breakthroughs in time-varying photonics are fueling novel, to the best of our knowledge, thermal emission phenomena, e.g., showing that the dynamic amplification of quantum vacuum fluctuations, induced by the time modulation of material properties, enables a mechanism to surpass the blackbody spectrum. So far, this issue has only been investigated under the assumption of non-dispersive time modulations. In this work, we identify the existence of a non-physical diverging behavior in the time-modulated emission spectra at high frequencies and prove that it is actually attributed to the simplistic assumption of a non-dispersive (temporally local) response of the time modulation associated with memory-less systems. Accordingly, we upgrade the theoretical formalism by introducing a dispersive response function, showing that it leads to a high-frequency cutoff, thereby eliminating the divergence and hence allowing for the proper computation of the emission spectra of time-modulated materials.

Detectability of Emission from Exoplanet Outflows Calculated by pyTPCI, a New 1D Radiation-hydrodynamic Code

Abstract Photoevaporation in exoplanet atmospheres is thought to contribute to the shaping of the small planet radius valley. Escaping atmospheres have been detected in transmission across a variety of exoplanet types, from hot Jupiters to mini-Neptunes. However, no work has yet considered whether outflows might also be detectable in emission. We introduce pyTPCI, a new, open-source self-consistent 1D radiative-hydrodynamics code that is an improved version of The PLUTO-CLOUDY Interface. We use pyTPCI to model seven exoplanets (HD 189733b, HD 209458b, WASP-69b, WASP-107b, TOI-1430b, TOI-560b, and HAT-P-32b) at varying metallicities and compute their emission spectra to investigate their detectability across a variety of spectral lines. We calculate the eclipse depths and signal-to-noise ratios (SNRs) of these lines for a 10 m class telescope with a high-resolution spectrograph, taking into account appropriate line broadening mechanisms. We show that the most detectable spectral lines tend to be the 589 nm Na i doublet and the 1083 nm metastable helium triplet. Hα and Mg i 457 nm are moderately strong for some planets at some metallicities, but they are almost always optically thin, so some of their emission may not be from the outflow. The planet with the highest-flux, highest-eclipse-depth, and highest-SNR lines is HD 189733b, with a Na i eclipse depth of 410 ppm and SNR of 2.4 per eclipse, and a He* eclipse depth of 170 ppm and SNR of 1.3. These signals would be marginally detectable with Keck if 3–10 eclipses were observed, assuming (over optimistically) photon limited observations.

Effect of beam divergence on the irradiance from dental light curing units.

This study measured the beam divergence angle and light output from dental light curing units (LCUs). Twenty LCUs were assessed using a laboratory-grade wide beam imager to determine the relationship between the beam divergence on the irradiance as a function of distance from the light tip. The irradiance (mW/cm2) and beam divergence angles (°) at 5, and 10 mm from the tips of 18 Light-Emitting Diode (LEDs), 1 Quartz-Tungsten-Halogen (QTH), and 1 Laser diode LCU. There were significant differences in the power, irradiance, and emission spectra from the 20 LCUs. At 10 mm from the LCU tip, the irradiance delivered by one LCU decreased by approximately 85.7 %, whereas this decrease was as low as 5.6 % for a different LCU. There was a positive correlation between the divergence angle reported by the wide beam imager and the reduction in irradiance. The laser diode LCU had the least beam divergence and the smallest decrease in irradiance as the distance increased. In contrast, the QTH LCU with the turbo light guide had the greatest beam divergence and the greatest reduction in irradiance as the distance increased. 50 % of the LCUs tested would require exposure times longer than 20 s to deliver 10 J/cm2 at the 10 mm distance. The wide beam imager is a useful tool for measuring the beam divergence from LCUs and predicting the effect of distance on their irradiance. At 10 mm, some LCUs may require a fivefold increase in the exposure time to deliver the same energy they deliver at 0 mm from the tip of the LCU.

Proposal and operational evaluation of a device for external and internal photodynamic therapy treatments

Photodynamic therapy (PDT) sources must match their emission spectrum with the absorption spectrum of the photosensitizer, provide precise treatment definition, deliver adequate irradiance to avoid thermal damage, and minimize treatment duration. Additionally, they should be adaptable to different photosensitizers, easy to manipulate, and cost-effective.Current LED sources are difficult to customize, rigid, and primarily designed for broad-area treatments. For localized treatments, laser technology is commonly employed.We propose a customizable and programmable LED-based device that not only meets these specifications but also addresses the limitations of current LED sources for localized treatments. It allows for the connection of a fiber optic terminal for internal treatments and can be fitted with light-diffusing devices capable of treating lesions externally or penetrating them internally. This device is an enhanced version of a previously developed source that has demonstrated efficacy in several pilot studies of photodynamic therapy.The proposed equipment shows significant potential for both medical and research applications, enabling the configuration of emission spectra on demand and the establishment of tailored treatment protocols based on the type of lesion being treated.

Investigating the binding of fluorescent probes to a trypanosomal-tRNA synthetase: A fluorescence spectroscopic and molecular dynamics study.

Given the high prevalence of Chagas disease in the Americas, we targeted the unique arginyl-tRNA synthetase of its causative agent Trypanosoma cruzi. Among their many possible uses, naphthalene-derived fluorescent ligands, such as ANS and bis-ANS, may be employed in pharmacokinetic research. Although ANS and bis-ANS have become prominent fluorescent probes for protein characterization, the structural and spectroscopic characteristics of protein-ANS/bis-ANS complexes remain largely unknown. Both fluorescent dyes bind to either the folded or partially folded hydrophobic regions of proteins. Additionally, they serve to identify molten globule-like intermediates. These probes have been used to study the folding problems of protein structures and the mechanisms of protein-protein interactions. ANS and bis-ANS exhibited significant enhancement and blue shift in their emission spectra upon binding to TcArgRS, the primary enzyme responsible for attaching l-arginine to its corresponding tRNA. Through fluorescence spectroscopy and computational studies, we concluded that bis-ANS binds more tightly to TcArgRS and that ATP affects bis-ANS fluorescence signal. Thus, these probes are useful resources for studying the intricate intermolecular relationships between proteins in terms of their structure, function, and mechanism. Our study provides a framework for identifying the hydrophobic regions present in TcArgRS. The utilization of hydrophobic patches on proteins for drug targeting is noteworthy because they can assist in identifying regions on the surface of proteins that are likely to interact with ligands. These patches help identify hotspot residues that play a vital role in determining binding affinity. Drugs are mainly small and hydrophobic in nature, and they target protein surfaces which have complementary properties. In this study, we elucidated the potential of TcArgRS as a target for combating trypanosomal diseases and extending life expectancy.

KrF exciplexes formation in low temperature plasmas created in various gas mixtures

Krypton fluoride exciplexes are short-lived species that can be generated in the excited state. Excimers and exciplexes do not form stable molecules in the ground state and, for this reason, must be brought to excited states in order to produce them. One method that can lead to the formation of exciplexes is a source based on gas targets and pulsed lasers. Our work focuses on mixture gases investigated using radiation pulses from Xe–He gas puff target and laser-produced plasma. UV/VIS spectroscopy was used in the 200–780 nm range as a diagnostic tool. The diatomic KrF species were observed in emission spectra, mainly in the KrF B and D states. The electron temperature and electron density of plasma containing the exciplexes were determined. The influence of relative intensities of the krypton emission lines and bands, as well as the changes in gas mixtures on the resulting spectra, was analyzed. The results may provide new insights into KrF exciplexes, which have not been studied from this point of view for many years.

Retraction notice to “Potential energy surface, effect of solvents in molecular level, experimental spectra (FTIR, Raman, UV-Visible & NMR), electronic, and dynamics simulation of isobavachalcone – Anti tuberculosis agent” [J. Mol. Liquids 392(Part 1) (2023) 123465

Retraction notice to “Potential energy surface, effect of solvents in molecular level, experimental spectra (FTIR, Raman, UV-Visible & NMR), electronic, and dynamics simulation of isobavachalcone – Anti tuberculosis agent” [J. Mol. Liquids 392(Part 1) (2023) 123465

Comprehensive assessment of broad beam transmission factors for nuclear medicine shielding.

This study aims to calculate broad beam transmission factors (BBTF) for common nuclear medicine shielding materials (lead, lead glass, concrete, barite concrete, and iron) using consistent Monte Carlo (MC) simulations. Additionally, the feasibility of fitting these transmission factors to the Archer model was explored. Photon emission spectra and biodistributions of eleven radionuclides (11C, 15O, 18F, 67Ga, 68Ga, 99mTc, 123I, 131I, 153Sm, 177Lu, and 201Tl) were analyzed. BBTFs were calculated for five shielding materials using both point sources and anthropomorphic phantoms to reflect practical clinical conditions. Validation was performed by comparing results with published data. BBTFs for eleven radionuclides and five shielding materials were obtained. The calculated half-value layer, tenth-value layer, centesimal value layer, and millesimal value layer thicknesses demonstrate good agreement with experimental and reference data for point sources. Results for phantom sources extend existing methodologies for PET shielding calculations to other radionuclides used in clinical practice. Findings indicate a reduction in shielding thickness due to changes in the radiation spectrum from body self-attenuation and highlight the impact of radionuclide biodistribution on BBTFs. The Archer model was not suitable for all sources, particularly low-energy ones. The study provides a validated basis for BBTF calculations across different sources and materials. Results demonstrate the need to account for body self-attenuation and biodistribution in shielding design. Future work should consider different biodistributions, phantom positions and generalized fitting models.

Fused nonacyclic carbonyl/nitrogen-containing multi-resonance emitters with simultaneously redshifted and narrowed emission spectra for high-efficiency solution-processed OLEDs

Fused nonacyclic carbonyl/nitrogen-containing multi-resonance emitters with simultaneously redshifted and narrowed emission spectra for high-efficiency solution-processed OLEDs

Dynamic in vivo monitoring of granum structural changes of Ctenanthe setosa (Roscoe) Eichler during drought stress and subsequent recovery.

Investigating the effects of drought stress and subsequent recovery on the structure and function of chloroplasts is essential to understanding how plants adapt to environmental stressors. We investigated Ctenanthe setosa (Roscoe) Eichler, an ornamental plant that can tolerate prolonged drought periods (40 and 49 days of water withdrawal). Conventional biochemical, biophysical, physiological and (ultra)structural methods combined for the first time in a higher plant with in vivo small-angle neutron scattering (SANS) were used to characterize the alterations induced by drought stress and subsequent recovery. Upon drought stress, no significant changes occurred in the chloroplast ultrastructure, chlorophyll content, 77K fluorescence emission spectra and maximal quantum efficiency of PSII (Qy dark), but the actual quantum efficiency of PSII (Qy light) decreased, the amounts of PSI-LHCII complexes and PSII monomers declined, and that of PSII supercomplexes increased. Thickness of the leaf and of the adaxial hypodermis, chloroplast length and granum repeat distance (RD) values decreased upon drought stress, as shown by light microscopy and SANS, respectively. Because of the very slight (nm-range) changes in RD values, the large biological variability (significant differences in RD values among the leaves and studied leaf regions) and the invasive sampling required for this method, transmission electron microscopy (TEM) hardly showed significant differences. On the other side, in situ SANS analyses provided a unique insight in vivo into the fast structural recovery of the granum structure of drought-stressed leaves, which happened already 18 h after re-watering, while functional and biochemical recovery took place on a longer time scale.

Influence of zinc on electrochemical and photoluminescence properties of yttrium chromate nanoparticles

YCrO4: Zn (1-9 mol %) nanoparticles were synthesized using Aloe vera gel via a solution combustion method and subsequently calcined at 600 °C for 3 h. X-ray diffraction analysis confirmed a pure tetragonal crystal structure, indicative of high material quality, while surface morphology revealed irregularly shaped and sized nanoparticles that varied with dopant concentration. The crystallite size, calculated using Scherrer’s method, decreased from 14 nm to 9 nm, and the optical energy band gap narrowed from 2.93 eV to 2.75 eV with increasing zinc doping. Photoluminescence emission spectra, recorded under 310 nm excitation, displayed peaks centered at 483, 525, and 628 nm, with the violet-blue emission attributed to the recombination of zinc interstitial (Zni) and zinc vacancy (VZn) energy levels. The presence of oxygen vacancies contributed to the green emission peak, while red emissions resulted from band transitions between zinc interstitial and oxygen interstitial (Oi) defect levels within the host matrix. The CIE coordinates fell within the 1713 K region, with an average color-correlated temperature of 1730 K, indicating a warm LED output. Electrochemical studies demonstrated that the specific capacitance of YCrO4:Zn (1-9 mol%) nanoparticles ranged from 86.94 to 130.27 F/g at a scan rate of 10 mV/s, underscoring the significant influence of dopant concentration on the material’s electrochemical properties, as higher concentrations of Zn2+ in YCrO4 enhanced the charge storage capability, suggesting its potential for improved performance in energy storage applications.

Microwave Synthesis of Luminescent Recycled Glass Containing Dy2O3 and Sm2O3

This research studied the recycling of borosilicate glass wastes from damaged laboratory glassware. The luminescent glasses were prepared by doping glass waste powder with rare earth ions, namely, dysprosium ions (Dy3+) and samarium ions (Sm3+), as well as co-doping with Dy3+ and Sm3+ at a concentration of 2% by weight. The sintering process was conducted in a microwave oven for a duration of 15 min. The photoluminescence spectra of the doped glasses were obtained under excitation at 401 nm and 388 nm. The results showed that the emission characteristics depended on the doping concentrations of Dy3+ and Sm3+ and the excitation wavelengths. Upon excitation at 401 nm, the co-doped glasses exhibited the maximum emission peak of Sm3+ at 601 nm (yellowish and orange region in the CIE chromaticity diagram) due to the energy transition from 4G5/2 to 6H7/2. When excited at 388 nm, however, the emission spectra of the co-doped glasses were similar to the characteristic emission peaks of Dy3+ (white region in the CIE chromaticity diagram), but the peak position exhibits a red shift. This could be attributed to an increase in the amount of non-bridging oxygens (NBOs) by co-doping.

Enhancing feature-aided data association tracking in passive sonar arrays: An advanced Siamese network approach.

Feature-aided tracking integrates supplementary features into traditional methods and improves the accuracy of data association methods that rely solely on kinematic measurements. However, previous applications of feature-aided data association methods in multi-target tracking of passive sonar arrays directly utilized raw features for likelihood calculations, causing performance degradation in complex marine scenarios with low signal-to-noise ratio and close-proximity trajectories. Inspired by the successful application of deep learning, this study proposes BiChannel-SiamDinoNet, an advanced network derived from the Siamese network and integrated into the joint probability data association framework to calculate feature measurement likelihood. This method forms an embedding space through the feature structure of acoustic targets, bringing similar targets closer together. This makes the system more robust to variations, capable of capturing complex relationships between measurements and targets and effectively discriminating discrepancies between them. Additionally, this study refines the network's feature extraction module to address underwater acoustic signals' unique line spectrum and implement the knowledge distillation training method to improve the network's capability to assess consistency between features through local representations. The performance of the proposed method is assessed through simulation analysis and marine experiments.

ExoMolHR: A Relational Database of Empirical High-resolution Molecular Spectra

Abstract ExoMolHR is an empirical, high-resolution molecular spectrum calculator for the high-temperature molecular line lists available from the ExoMol molecular database. Uncertainties, where available, in recommended ExoMol data sets are used to select highly accurate spectral lines. These lines largely rely on empirical energy levels generated through the MARVEL procedure, which is being systematically used to improve the energy and transition data provided by the ExoMol database. The freely accessible ExoMolHR database provides line positions with calculated intensities for a user-specified wavenumber/wavelength range and temperature. Spectra can be plotted on the ExoMolHR website https://www.exomol.com/exomolhr/ or downloaded as a .csv file. Cross sections can be calculated using the Python program PyExoCross. The ExoMolHR database currently provides 24,307,135 spectral lines for 33 molecules and 58 isotopologues; these numbers will increase as the ExoMol database is updated.

Plexciton Photoluminescence in Strongly Coupled 2D Semiconductor-Plasmonic Nanocavity Hybrid.

Strong plasmon-exciton interaction between two-dimensional transition metal dichalcogenides and a plasmonic nanocavity under ambient conditions has been reported extensively. But the suspicion on whether it has reached a true "strong coupling" is always there because the commonly used dark-field scattering spectroscopy shows a larger spectral splitting and the splitting in the photoluminescence spectra is absent. Here, by using a nanobipyramid-over-mirror to enhance the in-plane vacuum field, we achieve spectral Rabi splitting in both scattering and differential reflection spectra and observe a clear photoluminescence emission of the lower plexciton branch. The established nanocavity offers two polarization-dependent gap plasmon resonances to provide excitation and quantum yield enhancement simultaneously, yielding a total photoluminescence enhancement of 2.1 × 104 times. This allows the acquisition of emission spectra from an individual coupled system regardless of the presence of an uncoupled emitting background in the collection area. The sharp tips of the nanobipyramid lead to a large single-exciton coupling strength up to a few meV. Correlated scattering, differential reflection, and photoluminescence spectra reveal the similarity between the scattering and normalized photoluminescence spectra. These correlative measurements on a single coupled system clear up the suspicions of strong plasmon-exciton interactions and will promote the development of light-emitting plexcitonic devices at room temperature.