Light Source Research Articles

Programmable C-N Bond Formation through Radical-Mediated Chemistry in Plasma-Microdroplet Fusion.

Non-thermal plasma discharge produced in the wake of charged microdroplets is found to facilitate catalyst-free radical mediated hydrazine cross-coupling reactions without the use of external light source, heat, precious metal complex, or trapping agents. A plasma-microdroplet fusion platform is utilized for introduction of hydrazine reagent that undergoes homolytic cleavage forming radical intermediate species. The non-thermal plasma discharge that causes the cleavage originates from a chemically etched silica capillary. The coupling of the radical intermediates gives various products. Plasma-microdroplet fusion occurs online in a programmable reaction platform allowing direct process optimization and product validation via mass spectrometry. The platform is applied herein with a variety of hydrazine substrates, enabling i) self-coupling to form secondary amines with identical N-substitutions, ii) cross-coupling to afford secondary amine with different N-substituents, iii) cross-coupling followed by in situ dehydrogenation to give the corresponding aryl-aldimines with two unique N-substitutions, and iv) cascade heterocyclic carbazole derivatives formation. These unique reactions were made possible in the charged microdroplet environment through our ability to program conditions such as reagent concentration (i. e., flow rate), microdroplet reactivity (i. e., presence or absence of plasma), and reaction timescale (i. e., operational mode of the source). The selected program is implemented in a co-axial spray format, which is found to be advantageous over the conventional one-pot single emitter electrospray-based microdroplet reactions.

A Portable Photocollector for the Field Collection of Insects in Biodiversity Assessment.

Arthropod biodiversity research usually requires large sample collections. The efficient handling of these samples has always been a critical bottleneck. Sweep netting along transects is an effective and commonly used approach to sample diverse insects. However, sweep netting requires the time-consuming task of sorting insects from the large amounts of debris and foliage that end up in the sweep net along with the insects. To address this, we introduce a robust, portable, and inexpensive photocollector device with an LED light source to extract insects from sweep net samples in a standardized way. Timed field trials tested the photocollector's efficiency in extracting live insect samples from debris, focusing on Hymenoptera and Diptera. We found that 73% (±13%) of undamaged specimens moved toward the collection bottle within the first hour and 79% (±13%) after four hours. Of the insects failing to move after four hours, most (81%) were damaged and likely unable to move. Accounting only for undamaged specimens, 83% (±11%) moved after 1 h and 90% (±11%) moved after 4 h. We found significant differences in when families of Hymenoptera and Diptera moved. We suggest that the photocollector can be a useful tool in standardized biodiversity assessments.

Plasmon–Exciton–Polariton Condensation in Organic Semiconductor‐Covered Plasmonic Lattices

AbstractExciton–polariton condensates featuring collective coherence and large nonlinearities are promising for advancing coherent light sources and functional devices. Nevertheless, their reliance on planar cavities with large lateral device footprints and mode volumes hinders device integration. Plasmon–exciton–polaritons (PEPs), arising from the strong coupling between excitons and plasmons, provide an intriguing platform to explore emergent polariton condensation at the nanoscale due to their ultrasmall mode volumes in metal nanoparticles. However, the substantial radiative and Ohmic losses in metals hamper PEPs condensation, particularly in the short wavelength range (<600 nm). Here, a method is proposed to address metal losses by integrating organic semiconductor neat films onto plasmonic lattices. The use of organic semiconductors with large transition dipole moment and low non‐radiation loss enables efficient coupling between massive excitons and lattice plasmons, leading to high‐density PEPs. This ensures a macroscopic number of polaritons populating the low‐lying band edge at relatively low fluences to obtain bosonic stimulation, resulting in PEP condensation. By tailoring the band structures of plasmonic lattices, the condensation of PEPs are further manipulated into different energy states. These findings offer valuable insights for the design of PEP systems and all‐optical polaritonic devices.

Enhanced Quantum Efficiency via Co-Substitution in Red-Emitting Phosphor Sr2[MgAl5N7] : Eu2+ for Advanced Spectroscopic Applications Including Laser Displays with Ultra-High Luminescence Saturation Threshold.

In order to obtain novel and more efficient red light-emitting materials, a series of Sr2[Mg1-xLixAl5-xSixN7] : 0.01Eu2+ (SMAN-xLS, 0≤x≤0.5) red phosphors were devised and successfully synthesized via the high temperature solid state reaction and the effects of the co-substitution of [Mg-Al]5+ by [Li-Si]5+ on structural and luminescence properties is investigated in detail. A series of powder XRD data and Rietveld refinement indicate that [Li-Si]5+ co-substitution can successfully enter the Sr2[MgAl5N7] : 0.01Eu2+ (SMAN) lattice. With the entry of [Li-Si]5+ into the lattice, the substitution of Al3+ by Si4+ leads to the weakening of the nephelauxetic effect of the 5d level of Eu2+, which shifts the emission peak from 657 nm to 647 nm and reduces the excitation in the green region, i.e., lowers the absorption of green light. When the amount of [Li-Si]5+ co-substitution is x=0.1, the luminescence intensity and thermal stability of the sample are enhanced, in which the external quantum efficiency (EQE), reflecting the luminescence intensity, is elevated by 49.6 %. The increase in lattice rigidity gives rise to higher luminescence intensity, and the introduced trap levels for the compensation of luminescence enhances the thermal stability. Under blue laser excitation, the SMAN-0.1LS can achieve an ultra-high luminescence saturation threshold of 52.22 W/mm2, which is remarkably superior to other existing red phosphors, a breakthrough performance that has enormous potential for application in high-power laser display light sources. Cathodoluminescence (CL) characterization and measurements attest to the favorable CL properties of SMAN-0.1LS. By measuring the pressure-dependent luminescence of SMAN-0.1LS, the emission peak can be shifted from 650 nm to 702 nm with the increase of pressure, and the sensitivity dλ/dP is 5.07 nm/GPa, which is indicative of the potential application of this system as an optical pressure sensor.

Enhanced Quantum Efficiency via Co‐Substitution in Red‐Emitting Phosphor Sr2[MgAl5N7] : Eu2+ for Advanced Spectroscopic Applications Including Laser Displays with Ultra‐High Luminescence Saturation Threshold

AbstractIn order to obtain novel and more efficient red light‐emitting materials, a series of Sr2[Mg1−xLixAl5−xSixN7] : 0.01Eu2+ (SMAN‐xLS, 0≤x≤0.5) red phosphors were devised and successfully synthesized via the high temperature solid state reaction and the effects of the co‐substitution of [Mg−Al]5+ by [Li−Si]5+ on structural and luminescence properties is investigated in detail. A series of powder XRD data and Rietveld refinement indicate that [Li−Si]5+ co‐substitution can successfully enter the Sr2[MgAl5N7] : 0.01Eu2+ (SMAN) lattice. With the entry of [Li−Si]5+ into the lattice, the substitution of Al3+ by Si4+ leads to the weakening of the nephelauxetic effect of the 5d level of Eu2+, which shifts the emission peak from 657 nm to 647 nm and reduces the excitation in the green region, i.e., lowers the absorption of green light. When the amount of [Li−Si]5+ co‐substitution is x=0.1, the luminescence intensity and thermal stability of the sample are enhanced, in which the external quantum efficiency (EQE), reflecting the luminescence intensity, is elevated by 49.6 %. The increase in lattice rigidity gives rise to higher luminescence intensity, and the introduced trap levels for the compensation of luminescence enhances the thermal stability. Under blue laser excitation, the SMAN‐0.1LS can achieve an ultra‐high luminescence saturation threshold of 52.22 W/mm2, which is remarkably superior to other existing red phosphors, a breakthrough performance that has enormous potential for application in high‐power laser display light sources. Cathodoluminescence (CL) characterization and measurements attest to the favorable CL properties of SMAN‐0.1LS. By measuring the pressure‐dependent luminescence of SMAN‐0.1LS, the emission peak can be shifted from 650 nm to 702 nm with the increase of pressure, and the sensitivity dλ/dP is 5.07 nm/GPa, which is indicative of the potential application of this system as an optical pressure sensor.

Evaluation of photocathode materials in combination with commercial fiber-coupled UV photon sources as a compact electron source in mass spectrometry

Abstract The design of a compact electron source for mass spectrometry applications based on commercially available plug-and-play light sources and sturdy materials is presented, and its performance of photo-electron production is evaluated. We report quantum yields ranging between 1 – 2.5 x10-5 for aluminum, 9 x10-8 – 3 x10-6 for stainless steel, 1 – 2.2 x10-6 for molybdenum, 6.3 x10-7 – 5.1 x10-6 for tantalum, and 1.4 – 2.1 x10-6 for titanium, depending on the wavelength range of the irradiation source. In terms of quantum yield, the deuterium lamp provided better results compared to the two UV LEDs for all metals. However, due to their higher optical output power, the LEDs nevertheless yield a higher photoelectron current for all metals except for stainless steel. The measured photo-currents ranged from 1 – 2 nA for aluminum to 0.01 nA for Stainless Steel samples.

Acné queloideo de la nuca, un reto terapéutico para los dermatólogos

Acne keloidalis nuchae (AKN) is a chronic inflammatory dermatosis of the scalp that causes scarring alopecia. The etiology of AKN has been associated with an immune response vs. follicular antigens. AKN is characterized by fibrotic papules and plaques that can converge in tumor-like lesions; subclinical disease has been reported in perilesional areas, which could impact its development. Early diagnosis and treatment are essential to reduce morbidity and preserve and minimize healing. Various treatments have been established including optimal medical therapy, surgical excision, and light sources. An updated description of treatments (algorithm included) used for AKN is suggested based on the clinical lesions.

Determining sources in the bioluminescence tomography problem

Abstract In this paper, we revisit the bioluminescence tomography\,(BLT) problem, where one seeks to reconstruct bioluminescence signals (an internal light source) from external measurements of the Cauchy data. As one kind of optical imaging, the BLT has many merits such as high signal-to-noise ratio, non-destructivity and cost-effectiveness etc., and has potential applications such as cancer diagnosis, drug discovery and development as well as gene therapies and so on. In the literature, BLT is extensively studied based on diffusion approximation (DA) equation, where the distribution of peak sources is to be reconstructed and no solution uniqueness is guaranteed without adequate a priori information. Motivated by the solution uniqueness issue, several theoretical results are explored. The major contributions in this work that are new to the literature are two-fold: first, we show the theoretical uniqueness of the BLT problem where the light sources are in the shape of $C^2$ domains or polyhedral- or corona-shaped; second, we support our results with plenty of problem-orientated numerical experiments.

Design of a calibratable optical antenna system based on ring array light source

Abstract This study presents a multi-wavelength, multi-channel, and high-capacity optical antenna system. This approach is intended to allow parallel transmission with many channels and wavelengths by employing a ring array of vertical-cavity surface-emitting lasers, with reception accomplished via a ring detector array. The system employs spatially multiplexed techniques to send the target with numerous independent signals at the same time, effectively increasing bandwidth and reducing signal interference. The method used in this design provides benefits such as effective decreasing losses caused by blocking and removing aberrations. To overcome the spatial alignment difficulty caused by the array light source’s tiny beam size during long-distance transmission, this study introduces a high-precision acquisition, pointing, and tracking system as a reverse communication channel. The system’s wide beam can be used to align the installation of optical antenna equipment and facilitate information transmission.

Minimizing Voltage Deficit in Perovskite Indoor Photovoltaics by Interfacial Engineering.

Metal halide perovskites with bandgap of ≈1.8eV are competitive candidates for indoor photovoltaic (IPV) devices, owing to their superior photovoltaic properties and ideal absorption spectra matched to most indoor light sources. However, these perovskite IPVs suffer from severe trap induced non-radiative recombination, resulting in large open-circuit voltage (VOC) losses, particularly under low light intensity. Herein, an effective approach is developed to minimizing trap density by modifying the buried interface of perovskite layer with bifunctional molecular 2-(4-Fluorophenyl)ethylamine Hydrobromide (F-PEABr). The benzene ring of F-PEABr molecules can firmly anchor at the hole transporting layer by π-π stacking interaction, and the other ends can passivate the defects on the buried interface of perovskite layer. Based on that, the F-PEABr modified perovskite IPVs achieved power conversion efficiency (PCE) of 42.3% with a remarkable VOC of 1.13V under 1000 lux illumination from a 4000K LED lamp. Finally, perovskite IPV mini-modules with area of 10.40cm2 are demonstrated with a PCE of 35.2%. This interface modification strategy paves the way for crafting high-performance perovskite IPVs, holding great potential for self-powered internet of things applications.

Battle of the CH motions: aliphatic vs. aromatic contributions to astronomical PAH emission and exploration of the aliphatic, aromatic, and ethynyl CH stretches

Abstract Strong anharmonic coupling between vibrational states in polycyclic aromatic hydrocarbons (PAH) produces highly mixed vibrational transitions that challenge the current understanding of the nature of the astronomical mid-infrared PAH emission bands. Traditionally, PAH emission bands have been characterized as either aromatic or aliphatic, and this assignment is used to determine the fraction of aliphatic carbon in astronomical sources. In reality, each of the transitions previously utilized for such an attribution is highly mixed with contributions from both aliphatic and aromatic CH motions as well as non-CH motions such as CC stretches. High-resolution gas-phase IR absorption measurements of the spectra of the aromatic molecules indene and 2-ethynyltoluene at the Canadian Light Source combined with high-level anharmonic quantum chemical computations reveal the complex nature of these transitions, implying that the use of these features as a marker for the aliphatic fraction in astronomical sources is not uniquely true or actually predictive. Further, the presence of aliphatic, aromatic, and ethynyl CH groups in 2-ethynyltoluene provides an internally consistent opportunity to simultaneously study the spectroscopy of all three astronomically important groups. Finally, this study makes an explicit connection between fundamental quantum mechanical principles and macroscopic astronomical chemical physics, an important link necessary to untangle the lifecycle of stellar and planetary systems.

Recycling spent LiNi1-x-yMnxCoyO2 cathodes to high-entropy NiCoMnAlFe-LDHs for controllable hydrogen generation via NaBH4 hydrolysis

The recycling and environmentally friendly application of toxic metal cations from spent lithium-ion batteries is a global environmental challenge. This study utilizes the high structural tolerance of layered double hydroxides (LDHs) to synthesize high-entropy NiCoMnAlFe-LDHs from spent LiNi1-x-yMnxCoyO2 cathodes and liquid wastes, achieving efficient recovery of toxic metal cations. The obtained high-entropy NiCoMnAlFe-LDHs demonstrated rapid photo-thermal conversion capability driven by infrared radiation, generating localized high temperature on the surface of catalyst and rapidly catalyzing the hydrolysis of NaBH4 solution for hydrogen evolution. The hydrogen evolution rate reaches 1.72 mol·h−1·g−1·W−1 driven by 1050 nm infrared laser irradiation. The hydrolysis reaction of NaBH4 ceases immediately upon turning off the light source, allowing for controllable hydrogen release from NaBH4 and effectively solve the scientific challenges for NaBH4 as hydrogen carrier. This study offers a new approach for the recycling of spent lithium battery and the green utilization of hazardous materials.

DESIGN OF A PORTABLE PHOTOTHERAPY UNIT FOR HYPERBILIRUBINEMIA USING SURFACE MOUNTING DEVICE LIGHT EMITTING DIODES

Hyperbilirubinemia is a condition of a high bilirubin level in newborns causing a yellowish color on newborns’ skin and sclera. One of the treatment methods commonly used for hyperbilirubinemia is phototherapy in which newborns are exposed to visible light, especially within the green-blue spectrum. This study aimed to design a prototype of a portable phototherapy unit for newborns with hyperbilirubinemia. The phototherapy unit was designed by using a Surface Mounting Device Light Emitting Diode (SMD LED) with a wavelength of 400-520 nm as a light source which was attached to a fabric inside a box made of acrylic. The SMD LED strips were arranged with a spacing of 5 cm between the SMD LED arrays. The system was equipped with a monitoring system using SHT11 as a temperature and humidity sensor as well as a timer to adjust the duration of exposure and the LCD. The prototype was tested by irradiating various concentrations of artificial bilirubin solutions with a blue light produced by the phototherapy unit. The results show that the system can reduce the concentration of artificial bilirubin solution with an average reduction of 30.8%. The system shows the potential to be used as a portable phototherapy unit, further improvement on the efficacy, safety and comfort of the unit is required.

Accelerating data acquisition with FPGA-based edge machine learning: a case study with LCLS-II

Abstract New scientific experiments and instruments generate vast amounts of data that need to be transferred for storage or further processing, often overwhelming traditional systems. Edge Machine Learning (EdgeML) addresses this challenge by integrating
Machine Learning (ML) algorithms with edge computing, enabling real-time data processing directly at the point of data generation. EdgeML is particularly beneficial for environments where immediate decisions are required, or where bandwidth and
storage are limited. In this paper, we demonstrate a high-speed configurable ML model in a fully customizable EdgeML system using a Field Programmable Gate Array (FPGA). Our demonstration focuses on an angular array of electron spectrometers,
referred to as the ’CookieBox,’ developed for the Linac Coherent Light Source II (LCLS-II) project. The EdgeML system captures 51.2 Gbps from a 6.4 GS/s analog to digital converter and is designed to integrate data pre-processing and ML inside an
FPGA. Our implementation achieves an inference latency of 0.2 μs for the ML model, and a total latency of 0.4 μs for the complete EdgeML system, which includes preprocessing, data transmission, digitization, and ML inference. The modular design of
the system allows it to be adapted for other instrumentation applications requiring low-latency data processing.

Comparison of different spectral ranges of UV-LED lighting for outdoor mosquito trapping in forested area in Thailand.

Mosquito surveillance is critical for actively tracking the location and monitoring population levels and the threat of mosquito-borne disease. Although light-emitting diodes (LEDs) light traps have grown in popularity, there is still a limited understanding of the application of light wavelengths for trapping nocturnally active wild mosquitoes in forest ecotypes. This study evaluated the performance of different UV wavelengths in trapping mosquito populations in a forested mountainous area in Nakhon Ratchasima province, Thailand. Traps with different UV wavelengths were deployed in 6 locations, following a 6 × 6 Latin square replicated 6 times over a total of 36 nights. Light traps were operated between 18:00 and 06:00 h from October 2022 to August 2023. Mosquitoes were separately collected from individual traps every 4 h at 22.00, 2.00, and 6.00 h. Mosquitoes were killed by placing in a freezer (- 20 °C) for at least 30 min and then were morphologically identified using illustrated keys for adult females. Traps fitted with the LED 365 wavelength light source were the most effective in capturing 790 (23.66%) of the total mosquitoes collected, followed by the UV fluorescent 632 (18.93%), with the other 4 LED wavelengths collecting between 16.89% (LED 385) and 12.64% (LED 375) of the mosquitoes. Culex was the most common genus, representing 56.00% of total mosquito abundance. LED 365 and LED 385 were comparable to the UV fluorescent traps (the standard reference). Optimal trapping times were during 18:00-22:00 h. Compared to the other wavelengths, LED 365 was significantly more effective at capturing Coquillettidia and Culex mosquitoes than the UV-based traps.

Versatile platform of 3D/2D/1D:ZnFe2O4/NiAl-LDH/MWCNTs nanocomposite for photocatalytic purification of dinoseb and electrocatalytic O2 evolution reaction

Integrating photocatalysis with electrocatalysis may represent a synergistic approach to address environmental and energy challenges. In this context, we explored synthesizing a series of nanocomposite materials using a solid-state approach involving simple grinding and subsequent thermal treatment for the photocatalytic purification of dinoseb and electrocatalytic oxygen evolution (OER). Interestingly, among the series of synthesized materials, 40 wt percentage of 3D/2D/1D:ZnFe2O4/NiAl-LDH/MWCNTs ternary nanocomposite (40-NZM) showed highly improved dinoseb detoxification and OER efficiencies compared to those of pure materials. Importantly, approximately 98% detoxification of dinoseb was observed within 75 min of irradiation time under a visible light source. Remarkably, the 40-NZM nanocomposite exhibited the highest rate constant value (k = 4.1 × 10−2 min−1) with a favorable R2 (0.98) parameter. Furthermore, 40-NZM showed promising electrocatalytic OER performance, requiring only 217 mV of overpotential to achieve 10 mAcm−2 of current density with a smaller Tafel slope of 66.6 mVdec−1. Additionally, long-term stability was tested by recording 2000 cyclic voltammetry (CV) cycles. The results revealed that 40-NZM could maintain its catalytic activity for a longer duration as it required only 227 mV to attain 10 mAcm−2 even after 2000 CV cycles. Consequently, these outstanding characteristics of 40-NZM nanocomposite underscore the significant potential for catalytic water purification and sustainable energy conversion.

Toward a Correct Description of Initial Electronic Coherence in Nonadiabatic Dynamics Simulations.

The recent improvement in experimental capabilities for interrogating and controlling molecular systems with ultrafast coherent light sources calls for the development of theoretical approaches that can accurately and efficiently treat electronic coherence. However, the most popular and practical nonadiabatic molecular dynamics techniques, Tully's fewest-switches surface hopping and Ehrenfest mean-field dynamics, are unable to describe the dynamics proceeding from an initial electronic coherence. While such issues are not encountered with the analogous coupled-trajectory algorithms or numerically exact quantum dynamics methods, applying such techniques necessarily comes with a higher computational cost. Here we show that a correct description of initial electronic coherence can indeed be achieved using independent-trajectory methods derived from the semiclassical mapping formalism. The key is the introduction of an initial sampling over the electronic phase space and a means of incorporating phase interference between trajectories, both of which are naturally achieved when working within the semiclassical mapping framework.

A Sodium Metal-Organic Framework with Deep Blue Room-Temperature Phosphorescence.

It is a great challenge to manufacture room-temperature blue long afterglow phosphorescent materials adapted to environmental conditions. Herein, an Na-based metal-organic framework (MOF) was constructed using Na+ and 1H-1,2,4-triazole-3,5-dicarboxylic acid, which exhibits long-lived of 378.9 ms, deep blue and room-temperature phosphorescence, meanwhile possesses the visible blue afterglow for 3~6 seconds after removing excitation light source. The three-dimensional coordination bonds network provided by Na-based MOF protects the organic ligands intrinsic hydrogen bond network, resulting in the phosphor lifetime and residual color remaining unchanged in different gas atmospheres. Furthermore, first-principles time-dependent density functional theory reveals that the rigid Na-based MOF structure can limit the rotation and vibration of the room-temperature phosphorescent organic ligands. This limitation results in the suppression of non-radiative decay for both singlet and triplet excitons, promotes intersystem crossing, and increases the rate of radiative decay, ultimately achieving long-lived room-temperature phosphorescence.

Photometric stereo light calibration optimization and high-reflective distance fitness compensation method to improve reconstruction

This paper proposes an interpolated light calibration optimization and high-reflective area compensation method to solve the accuracy loss caused by idealization of the photometric stereo (PS) model and high-reflective area. The spatial distribution model of light intensity is defined as a cubic interpolation function, which is used to obtain an intensity coefficient matrix to optimize the PS model. A light source adaptation model is adopted to select the appropriate position of the light source based on the characteristics of the object. Finally, a distance fitness compensation model is established to repair the high-reflective area, which selects the optimal pixel values of the non-high-reflective area. The experiment result shows that the proposed method can obtain the light source spatial characteristics, and high-reflective areas could be repaired.

Rapid Degradation of Dye Effluents with A SnS Catalyst: A Sustainable Approach Using Natural Light Under Ambient Conditions.

Dye degradation presents a persistent challenge in addressing water pollution. While several methods, including adsorption, biodegradation, and advanced oxidation processes, have been extensively explored, photocatalysis remains one of the most effective techniques. Conventional photocatalytic dye degradation processes often rely on expensive light sources and are time-intensive. Herein, we synthesized a SnS catalyst by the solvated metal atom dispersion (SMAD) method, using Sn foil and sulfur powder. The catalyst exhibited remarkable performance, achieving complete degradation of methylene blue within 2 minutes under ambient room light, without the need for any external light source. Similar degradation efficiency was achieved for methyl orange. To evaluate the role of light for the degradation, control experiments were conducted in the dark using methylene blue as a model dye. Although the degradation rate was slightly reduced, the catalyst still facilitated dye degradation in the absence of light. Additionally, the catalytic performance was tested with four other dyes under natural light, all of which yielded promising results, demonstrating the versatility and effectiveness of the SnS catalyst in dye degradation. This work highlights the potential of the SnS catalyst for efficient and rapid dye degradation under both light and dark conditions, offering an energy-efficient solution for wastewater treatment.