Search

Hyperdoping Si with transition metals to form intermediate bands for infrared absorption has attracted attention recently for producing sub-bandgap photoconductivity. In particular, Si hyperdoped with Au has been demonstrated to exhibit optoelectronic response at 1550 nm. However, the reported external quantum efficiencies (EQEs) are low, and the device fabrication processes had not been optimized. In this paper, we demonstrate a significant improvement in sub-bandgap EQE through modification of the material and device fabrication processes. By increasing the Si:Au layer thickness, modification of device design, and formation of Ohmic contacts, the EQE was measured to be as high as 0.44% at 1550 nm, nearly two orders of magnitude higher than previous reports from similar devices. Additionally, the EQE was measured to be in the 10-3 range for wavelengths as long as 2.4 μ m. The EQE spectrum showed features that were attributed to defect levels from a substitutional Au acceptor defect. The above bandgap EQE showed gain in one device. Thermal annealing at 300 ° C does not improve the efficiency of Si:Au photodiodes. These results demonstrate the viability of Au-hyperdoped Si for infrared detection below the bandgap of Si. [ABSTRACT FROM AUTHOR]

Ethane ( C 2 H 6 ) is anticipated to be the most stable compound within the carbon–hydrogen system under the 100 GPa pressure range. Nevertheless, the properties of ethane under pressure are still poorly documented. Here, we present a comprehensive study of the structural and vibrational properties of C 2 H 6 in a diamond anvil cell at pressures up to 150 GPa. To obtain detailed data, ethane single-crystal was grown in a helium pressure-transmitting medium. Utilizing single-crystal x-ray diffraction, the distortion mechanism between the tetragonal and monoclinic phases, occurring over the 3.2–5.2 GPa pressure range, is disclosed. Subsequently, no phase transition is observed up to 150 GPa. The accurately measured compression curve is compared to various computational approximations. The vibrational modes measured by Raman spectroscopy and infrared absorption are well identified, and their evolution is well reproduced by ab initio calculations. In particular, an unusual anticrossing phenomenon occurs near 40 GPa between a rocking and a stretching mode, likely attributable to intermolecular interactions through hydrogen bonding. [ABSTRACT FROM AUTHOR]

Colloidal quantum dots are of increasing interest for mid-infrared detection and emission, but device performances will vastly benefit from reducing the non-radiative recombination. Empirically, the photoluminescence quantum yield decreases exponentially toward the mid-infrared, which appears similar to the energy gap law known for molecular fluorescence in the near-infrared. For molecules, the mechanism is electron–vibration coupling and fast internal vibrational relaxation. Here, we explore the possible mechanisms for inorganic quantum dots. The primary mechanism is assigned to an electric dipole near-field energy transfer from the quantum dot electronic transitions to the infrared absorption of surface organic ligands and then to the multiphonon absorption of the quantum dot inorganic core or the surrounding inorganic matrix. In order to obtain luminescent quantum dots in the 3–10 μm range, we motivate the importance of using inorganic matrices, which have a higher infrared transparency compared to organic materials. At longer wavelengths, inter-quantum dot energy transfer is noted to be much faster than radiative relaxation, indicating that bright mid-infrared colloidal quantum dot films might then benefit from dilution. [ABSTRACT FROM AUTHOR]

Wurtzite ScxAl1−xN/GaN (x = 0.13–0.18) multi-quantum wells grown by molecular beam epitaxy on c-plane GaN are found to exhibit remarkably strong and narrow near-infrared intersubband absorption in the technologically important 1.8–2.4 μm range. Band structure simulations reveal that, for GaN wells wider than 3 nm, the quantized energies are set by the steep triangular profile of the conduction band caused by intrinsic polarization fields. As a result, the intersubband transition energies provide unique and direct access to essential ScAlN polarization parameters. Measured infrared absorption indicates that the spontaneous polarization difference of the presumed lattice-matched Sc0.18Al0.82N/GaN heterostructure is smaller than the theoretically calculated value. The intersubband transition energies are relatively insensitive to the barrier alloy composition indicating negligible variation of the net polarization field in the probed 0.13–0.18 Sc composition range. [ABSTRACT FROM AUTHOR]

DL_POLY Quantum 2.0, a vastly expanded software based on DL_POLY Classic 1.10, is a highly parallelized computational suite written in FORTRAN77 with a modular structure for incorporating nuclear quantum effects into large-scale/long-time molecular dynamics simulations. This is achieved by presenting users with a wide selection of state-of-the-art dynamics methods that utilize the isomorphism between a classical ring polymer and Feynman's path integral formalism of quantum mechanics. The flexible and user-friendly input/output handling system allows the control of methodology, integration schemes, and thermostatting. DL_POLY Quantum is equipped with a module specifically assigned for calculating correlation functions and printing out the values for sought-after quantities, such as dipole moments and center-of-mass velocities, with packaged tools for calculating infrared absorption spectra and diffusion coefficients. [ABSTRACT FROM AUTHOR]

Semiconducting MXenes are an intriguing two-dimensional (2D) material class with promising electronic and optoelectronic properties. Here, we focused on recently prepared Hf-based MXenes, namely, Hf3C2O2 and Hf2CO2. Using the first-principles calculation and excited state corrections, we proved their dynamical stability, reconciled their semiconducting behavior, and obtained fundamental gaps by using the many-body GW method (indirect 1.1 and 2.2 eV; direct 1.4 and 3.5 eV). Using the Bethe–Salpeter equation, we subsequently provided optical gaps (0.9 and 2.7 eV, respectively), exciton binding energies, absorption spectra, and other properties of excitons in both Hf-based MXenes. The indirect character of both 2D materials further allowed for a significant decrease of excitation energies by considering indirect excitons with exciton momentum along the Γ-M path in the Brillouin zone. The first bright excitons are strongly delocalized in real space while contributed by only a limited number of electron–hole pairs around the M point in the k-space from the valence and conduction band. A diverse range of excitonic states in Hf3C2O2 MXene lead to a 4% and 13% absorptance for the first and second peaks in the infrared region of absorption spectra, respectively. In contrast, a prominent 28% absorptance peak in the visible region appears in Hf2CO2 MXene. Results from radiative lifetime calculations indicate the promising potential of these materials in optoelectric devices requiring sustained and efficient exciton behavior. [ABSTRACT FROM AUTHOR]

The photochemical dynamics of the acetic acid and trifluoro-acetic acid dimers in hexane are studied using time-resolved infrared absorption spectroscopy and ab initio electronic structure calculations. The different hydrogen bond strengths of the two systems lead to changes in the character of the accessed excited states and in the timescales of the initial structural rearrangement that define the early time dynamics following UV excitation. The much stronger hydrogen bonding in the acetic acid dimer stabilizes the system against dissociation. Ground state recovery is mediated by a structural buckling around the hydrogen bond itself with no evidence for excited state proton transfer processes that are usually considered to drive ultrafast relaxation processes in hydrogen bonded systems. The buckling of the ring leads to relaxation through two conical intersections and the eventual reformation of the electronic and vibrational ground states on a few picosecond timescale. In trifluoro-acetic acid, the weaker hydrogen bonding interaction means that the dimer dissociates under similar irradiation conditions. The surrounding solvent cage restricts the full separation of the monomer components, meaning that the dimer is reformed and returns to the ground state structure via a similar buckled structure but over a much longer, ∼100 ps, timescale. [ABSTRACT FROM AUTHOR]

We describe Reflection Absorption Infrared Spectroscopy (RAIRS) and first-principles Density Functional Theory (DFT) studies of ammonia adsorption on the Cu{311} surface. Our experimental results indicate an upright chemisorbed species at low coverages, with at least one additional species accompanying this at higher coverages. Our high-coverage RAIRS data cannot be fully explained by DFT models containing only ammonia or its dissociation products, even allowing for molecular tilt and/or the formation of a bilayer. We therefore also consider urea and formamide as possible products of surface reaction with residual carbon monoxide, but these species are again not fully compatible with our observed spectra. The overlayer composition at high coverages remains mysterious. [ABSTRACT FROM AUTHOR]

The α-hydroxyethyl radical (CH3·CHOH, 2A) is a key intermediate in ethanol biochemistry, combustion, atmospheric chemistry, radiation chemistry, and astrochemistry. Experimental data on the vibrational spectrum of this radical are crucially important for reliable detection and understanding of the chemical dynamics of this species. This study represents the first detailed experimental report on the infrared absorption bands of the α-hydroxyethyl radical complemented by ab initio computations. The radical was generated in solid para-H2 and Xe matrices via the reactions of hydrogen atoms with matrix-isolated ethanol molecules and radiolysis of isolated ethanol molecules with x rays. The absorption bands with maxima at 3654.6, 3052.1, 1425.7, 1247.9, 1195.6 (1177.4), and 1048.4 cm−1, observed in para-H2 matrices appearing upon the H· atom reaction, were attributed to the OHstr, α-CHstr, CCstr, COstr + CCObend, COstr, and CCstr + CCObend vibrational modes of the CH3·CHOH radical, respectively. The absorption bands with the positions slightly red-shifted from those observed in para-H2 were detected in both the irradiated and post-irradiation annealed Xe matrices containing C2H5OH. The results of the experiments with the isotopically substituted ethanol molecules (CH3CD2OH and CD3CD2OH) and the quantum-chemical computations at the UCCSD(T)/L2a_3 level support the assignment. The photolysis with ultraviolet light (240–300 nm) results in the decay of the α-hydroxyethyl radical, yielding acetaldehyde and its isomer, vinyl alcohol. A comparison of the experimental and theoretical results suggests that the radical adopts the thermodynamically more stable anti-conformation in both matrices. [ABSTRACT FROM AUTHOR]

As one of the most widely used infrared (IR) detectors, a mercury cadmium telluride (MCT) detector usually requires liquid nitrogen refrigeration to suppress thermally activated noise mechanisms that are inherent to its narrow bandgap, which limits its practical applications. Therefore, it is essential to develop strategies to suppress dark current with reduced cooling demand. In this work, a surface plasmon resonance (SPR) enhanced MCT microcavity was proposed to intensify optical absorption across a broadband while diminishing the thickness of the MCT layer to reduce intrinsic dark current proportional to the volume of the absorber. The microcavity is formed by sandwiching the MCT layer between a top well-designed hybrid golden-cross antenna array and a bottom golden reflector. The microcavity is employed to trap the incident light to amplify the absorption, and the golden-cross antenna array is introduced to not only significantly enhance the incident light field through the SPR effect but also to broaden the microcavity resonant mode. Numerical calculation indicated that an absorptance exceeding 95.3% can be attained at 3.4 μm with the full width at half maxima (FWHM) extending beyond 1.38 μm, which almost covers the absorption band of MCT in mid-wavelength IR (MWIR), all while the MCT layer is only 530 nm. Moreover, the prototype device unit was fabricated and tested. Measured peak absorption reached 98.7% @ 3.6 μm and FWHM was as broad as 1.12 μm. These results demonstrate that the high and wideband absorption in an ultrathin MCT layer is achieved based on the synergistic effects of SPR and microcavity resonance. [ABSTRACT FROM AUTHOR]

The electronic and vibrational spectra of the meso-tetrakis(4-sulfonatophenyl)-porphyrins (TSPP) have been studied computationally using the PFD-3B functional with time-dependent density functional theory for the excited states. The calculated UV-vis absorption and emission spectra in aqueous solution are in excellent agreement with the experimental measurements of both H2TSPP−4 (monomer) at high pH and H4TSPP−2 (forming J-aggregate) at low pH. Moreover, our calculations reveal an infrared absorption at 1900 cm−1 in the singlet and triplet excited states that is absent in the ground state, which is chosen as a probe for transient IR absorption spectroscopy to investigate the vibrational dynamics of the excited state. Specifically, the S2 to S1 excited state internal conversion process time, the S1 state vibrational relaxation time, and the lifetime of the S1 excited electronic state are all quantitatively deduced. [ABSTRACT FROM AUTHOR]

Optically active spin defects in semiconductors can serve as spin-to-photon interfaces, key components in quantum technologies. Silicon carbide (SiC) is a promising host of spin defects thanks to its wide bandgap and well-established crystal growth and device technologies. In this study, we investigated the oxygen-vacancy complexes as potential spin defects in SiC by means of ab initio calculations. We found that the OCVSi defect has a substantially low formation energy compared with its counterpart, OSiVC, regardless of the Fermi level position. The OCVSi defect is stable in its neutral charge state with a high-spin ground state (S = 1) within a wide energy range near the midgap energy. The zero-phonon line (ZPL) of the OCVSi0 defect lies in the near-infrared regime, 1.11–1.24 eV (1004–1117 nm). The radiative lifetime for the ZPL transition of the defect in kk configuration is fairly short (12.5 ns). Furthermore, the estimated Debye–Waller factor for the optical transition is 13.4%, indicating a large weight of ZPL in the photoluminescence spectrum. All together, we conclude that the OCVSi0 defect possesses desirable spin and optical properties and thus is potentially attractive as a quantum bit. [ABSTRACT FROM AUTHOR]

The facet-dependent adsorption of CO on oxidized and reduced CeO2 single crystal surfaces is reviewed, with emphasis on the effect of CO coverage and the ability of state-of-the-art quantum-mechanical methods to provide reliable energies and an accurate description of the IR vibrational frequency of CO. Comparison with detailed, high-resolution experimental infrared reflection absorption spectroscopy data obtained for single crystal samples allows the assignment of the different CO vibrational bands observed on all three low-index ceria surfaces. Good agreement is achieved with the hybrid density functional theory approach with the HSE06 functional and with saturation coverage. It is shown that CO is very sensitive to the structure of cerium oxide surfaces and to the presence of oxygen vacancies. The combined theoretical-experimental approach offers new opportunities for a better characterization of ceria nanoparticles and for unraveling changes occurring during reactions involving CO at higher pressures. [ABSTRACT FROM AUTHOR]

A novel near-infrared emitting Ga 2 O 3 : Ni2+ phosphor was prepared, and its emission characteristics were improved through melting aid and charge balance. Under 410 nm excitation, the Ga 2 O 3 : Ni2+ phosphor exhibits broadband near-infrared emission in the second region, with a peak at 1455 nm and a half maximum width of up to 300 nm. At the same time, the crystallinity of the sample was improved and the charge imbalance during substitution between Ga3+ and Ni2+ was eliminated through melting assistance and charge compensation. The results show that the emission intensity of Ga 1.97 O 3 : 0.015Ni2+, 0.015Ge4+ phosphor (with added flux H 3 BO 3) is 10 times higher than that of Ga 1.985 O 3 : 0.015Ni2+ sample. Its quantum yield is as high as 31.2 %, significantly higher than the reported Ni2+ ion doped phosphors. According to the distinct absorptions of C–H, O–H as well as N–H bonds in the shortwave near-infrared range, samples of ethanol, n-hexanol, water and ammonia demonstrated different absorption peaks under the penetration of the constructed phosphor conversion light-emitting diode, which proved the potential application of Ga 2 O 3 : Ni2+, Ge4+-H 3 BO 3 phosphor in composition analysis and detection. [ABSTRACT FROM AUTHOR]

Summary: The composite film with collagen as the main component has been widely used due to its characteristics of non‐toxicity, environmental protection and health. Fish skin, a by‐product of fish, is an excellent source of collagen. Thus, collagen was extracted from an under‐utilised species, Atlantic cod (Gadus morhua) skin, and the composite film of fish skin collagen–chitosan–cinnamon essential oil was prepared by casting. The effects of the ratio of collagen to chitosan (2:8, 4:6, 5:5, 6:4, 8:2) and the concentration of essential oil (0%, 0.1%, 0.2%, 0.3%, and 0.4% (v/v)) on the composite film were studied. The structures of the composite films were analysed using scanning electron microscopy (SEM), Fourier transforms infrared spectroscopy (FTIR), and X‐ray diffractometry (XRD). The collagen content of Atlantic cod skin is approximately 50.12%, which is significantly higher than that found in basa fish and Nile tilapia (P < 0.05). The content of hydroxyproline was 4.51%. Analyses of tensile strength, elongation at break, water vapor permeability, and water solubility showed Co4Ch6 (Co:Ch = 4:6) had the optimal comprehensive performance, and Co4Ch6–0.2 (Co4Ch6 with 0.2% CEO) had high water resistance in the high‐humidity environment. As the CEO concentration rose, the composite films' infrared absorption bands were enhanced in amplitude, and the XRD peaks were gradually intensified, indicating the internal crystallinity and, thereby, the opacity of the composite films were improved. The bacteriostasis zones Co4Ch6–0.4 against Escherichia coli and Staphylococcus aureus were 2.02 cm and 1.73 cm, respectively. The DPPH radical scavenging rate of Co4Ch6 rose with the increase in CEO concentration, and the DPPH radical scavenging rate of C04Ch6–0.4 was up to 48.56%. Thus, the composite films prepared from fish skin collagen, chitosan, and cinnamon essential oils have outstanding mechanical properties, barrier ability, and antimicrobial activity and are promising for application in food packaging and storage. In addition, the composite films showed a potential antioxidation ability, which might be used as green bioactive films to preserve nutraceutical products. [ABSTRACT FROM AUTHOR]

How to maximize the extraction of heat by infrared radiation while reducing the thermal conductivity to prevent heat transfer is the main challenge of radiative thermal management for emerging industrial and aerospace applications. Herein, we reported a high-temperature broadband high emissivity (Y 0.5 Lu 0.5) 2 SiO 5 ceramic with emissivity above 0.9 at room temperature and above 0.61 at elevated temperature of 1200℃ across the entire range of wavelength (1–14μm). Lu-doped rare earth monosilicate with high lattice entropy has a more complex electronic structure, boosting the emissivity of near-infrared wavelength (1–3 μm), as well as enhanced emissivity in the MIR range (3–14 μm) is derived from the lattice distortion and extra multi-mode vibrations induced by the substitutional doping of Lu3+ into the host lattice. Moreover, based on Stephen-Boltzmann law and energy conservation law found that the emissivity of rare earth monosilicate-based ceramics is negatively correlated with temperature, which may be due to the fact that rising temperature increases damping of phonon vibration of the ceramic lattice, reducing the ability of infrared absorption. This doped rare earth monosilicate ceramic has a high emissivity at high temperatures above 1200 °C, revealing immense potential in the radiation thermal protection field. [ABSTRACT FROM AUTHOR]

Pervasive intrinsic defects have a significant impact on the electrocatalytic activity of carbon materials, but previous research has focused on the effects of topological structures exclusively. Herein, a compelling demonstration of the pivotal role played by the positions and spatial arrangement of intrinsic defects in determining their efficacy for electrochemical CO2 reduction (ECR) is presented. Theoretical calculations reveal a substantial reduction in energy barriers for *COOH formation at intrinsic defects positioned along the edges while hindering the transformation of *COOH to *CO in the ECR process. To address this issue, a sea urchin‐like nanocarbon (F1100) is designed, which provides adjacent intrinsic defects located in V‐type arranged carbon nanorods. The angulated edge intrinsic defects facilitate the bridge adsorption of carbon monoxide (CO), as confirmed by in situ attenuated total reflection surface‐enhanced infrared absorption spectroscopy, thereby enhancing the specific activity of ECR on intrinsic carbon defects. In a 0.1 m potassium bicarbonate (KHCO3) solution, F1100 achieves a FECO of 95.0%, while in an ionic liquids‐based electrolyte, a current density of 90.0 mA cm−2 is obtained with nearly complete conversion of CO2 to CO in an H‐type cell. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: The aggregation of α‐synuclein (α‐syn) is strongly influenced by membrane interfaces, but the mechanism of transition from monomers to oligomers at early aggregation stage is not clear. Here, we investigate the adsorption and structure changes of α‐syn on oppositely charged aromatic interfaces through in‐situ surface‐enhanced infrared absorption (SEIRA) spectroscopy and nano‐IR technique. The results show that the synergy of electrostatic and hydrophobic interactions leads to a "fast‐slow" two‐step aggregation pathway on negatively charged interface. Surface adsorption induces the formation of an extended helix structure and subsequently partial helix unwinding in NAC region, which enables the hydrophobic stacking between nearby NAC regions. Stable antiparallel β‐sheet rich aggregates are gradually emerging as further interactions of monomers with the fast formed "first layer". Monomers electrostatically adsorb on positively charged interface by C‐terminus with NAC region and N‐terminus stretched in solvent, which serve as an aggregation core and induce further adsorption and gradual formation of aggregates with C‐terminus exposure. Our results demonstrate the modulation of surface charge and synergy of electrostatic and hydrophobic interactions on the interaction modes and aggregation pathways, which provide insights into dynamic conformation changes of α‐syn at early aggregation stage and imply the important role of spatial‐temporal heterogeneity of membranes in α‐synucleinopathies. [ABSTRACT FROM AUTHOR]

ABSTRACT This study employs density functional theory to investigate whether asymmetric uranyl‐Salophen catalyzes the activation of 2,4‐dichlorophenol, 2,4,6‐trichlorophenol, and pentachlorophenol. Changes in various important parameters such as bond lengths, Wiberg bond indices, infrared vibrational absorption spectra, natural charge distributions, ultraviolet–visible absorption spectra, and 13C NMR chemical shifts of the aromatic rings of chlorophenols before and after forming complexes with asymmetric uranyl‐Salophen are analyzed. This means that asymmetric uranyl‐Salophen indeed activates 2,4‐dichlorophenol, 2,4, 6‐trichlorophenol, and pentachlorophenol, significantly lengthening the aromatic ring bonds of the three chlorophenols and increasing the electrophilicity of the carbon atoms in the aromatic ring. This suggests that the conjugated system of the aromatic ring is also partially disrupted, indicating that these three chlorophenols are indeed catalytically activated. Furthermore, this implies that this asymmetric uranyl‐Salophen may be used to degrade chlorophenols in water. [ABSTRACT FROM AUTHOR]

A dye-sensitised solar cell was fabricated using dry Ixora flower extract. The sensitiser was obtained by physical extraction using a mixture of ethanol and distilled water as solvent in the ratio of 7:3. The optical study of the sample was done within wavelength range of 230 nm to 1100 nm using spectrophotometer (UV- 750 series). The outcome shows an optimum absorption in the visible region of the EM spectrum, which shifted to the UV region when adsorbed onto a nano-porous TiO2 surface. An alternative peak of 0.95a.u in the visible region was observed with enhanced optical absorption across the infrared region of the spectrum. The absorption coefficient values suggest the extract absorbs light in the visible region, which was also confirmed with the relatively high extinction coefficient observed in the visible region of the EM spectrum. The extract exhibits a low transmittance in the visible range, which increases to over 99% in the red wavelengths. The extract has low reflectance of about 20% in the visible range, which falls lower as wavelength increases into the infrared region. The energy band gap (for direct transition) of 2.13 eV was obtained for dry Ixora dye extract. The fabricated solar cell performed a fill factor of 0.27, Jsc of 0.1273 mA/cm2, Voc of 0.7001 V, and conversion efficiency of about 0.02%. with these results, the dye extract of dry ixora flower can serve as a good photo-sensitiser for the fabrication of dye-sensitised solar cell. [ABSTRACT FROM AUTHOR]

Surface-enhanced infrared absorption (SEIRA) spectroscopy exploits the field enhancement near nanophotonic structures for highly sensitive characterization of (bio)molecules. The vibrational signature observed in SEIRA spectra is typically interpreted as field-enhanced molecular absorption. Here, we study molecular vibrations in the near field of single antennas and show that the vibrational signature can be equally well explained by field-enhanced molecular scattering. Although the infrared scattering cross section of molecules is negligible compared to their absorption cross section, the interference between the molecular-scattered field and the incident field enhances the spectral signature caused by molecular vibrational scattering by 10 orders of magnitude, thus becoming as large as that of field-enhanced molecular absorption. We provide experimental evidence that field-enhanced molecular scattering can be measured, scales in intensity with the fourth power of the local field enhancement and fully explains the vibrational signature in SEIRA spectra in both magnitude and line shape. Our work may open new paths for developing highly sensitive SEIRA sensors that exploit the presented scattering concept. The authors study molecular vibrations in the near field of single antennas, showing that the vibrational signature in SEIRA spectra can be explained by field-enhanced molecular scattering. This opens pathways for the development of sensitive SEIRA sensors exploiting this concept. [ABSTRACT FROM AUTHOR]

The enhancement of detection sensitivity in microfluidic sensors has been a continuously explored field. Initially, many strategies for sensitivity improvement involved introducing enzyme cascade reactions, but enzyme‐based reactions posed challenges in terms of cost, stability, and storage. Therefore, there is an urgent need to explore enzyme‐free cascade amplification methods, which are crucial for expanding the application range and improving detection stability. Metal or metal compound nanomaterials have gained great attention in the exploitation of microfluidic sensors due to their ease of preparation, storage, and lower cost. The unique physical properties of metallic nanomaterials, including surface plasmon resonance, surface‐enhanced Raman scattering, metal‐enhanced fluorescence, and surface‐enhanced infrared absorption, contribute significantly to enhancing detection capabilities. The metal‐based catalytic nanomaterials, exemplified by Fe3O4 nanoparticles and metal‐organic frameworks, are considered viable alternatives to biological enzymes due to their excellent performance. Herein, we provide a detailed overview of the applications of metals and metal compounds in improving the sensitivity of microfluidic biosensors. This review not only highlights the current developments but also critically analyzes the challenges encountered in this field. Furthermore, it outlines potential directions for future research, contributing to the ongoing development of microfluidic biosensors with improved detection sensitivity. [ABSTRACT FROM AUTHOR]

A novel pulsed power source capable of nanosecond pulses with burst frequencies up to 1 MHz is employed to create atmospheric pressure pulsed plasma in pure CO2 gas. The short bursts contain up to four nanosecond pulses. The CO2 conversion and corresponding energy efficiency are measured ex-situ with Fourier-transform infrared absorption spectroscopy. Trends in the absorption line profile of in-situ quantum cascade laser infrared absorption spectroscopy indicate an elevated vibrational temperature of CO2 with an increasing number of pulses per burst. The key result of this paper is that the dissociation energy efficiency is higher when operating the plasma in burst mode. Furthermore, a larger number of pulses in a burst is associated with a further increase of the dissociation efficiency. The highest efficiency measured is (17.7 ± 0.3) % for single pulses spaced 2 ms apart, and (20.0 ± 0.3) % for bursts of three pulses, with an in-burst frequency of 1 MHz and bursts spaced 4 ms apart. [ABSTRACT FROM AUTHOR]

Enniatins are mycotoxins with well‐known antibacterial, antifungal, antihelmintic and antiviral activity, which have recently come to attention as potential mitochondriotoxic anticancer agents. The cytotoxicity of enniatins is traced back to ionophoric properties, in which the cyclodepsipeptidic structure results in enniatin:cation‐complexes of various stoichiometries proposed as membrane‐active species. In this work, we employed a combination of surface‐enhanced infrared absorption (SEIRA) spectroscopy, tethered bilayer lipid membranes (tBLMs) and density functional theory (DFT)‐based computational spectroscopy to monitor the cation‐dependence (Mz+=Na+, K+, Cs+, Li+, Mg2+, Ca2+) on the mechanism of enniatin B (EB) incorporation into membranes and identify the functionally relevant EBn : Mz+ complexes formed. We find that Na+ promotes a cooperative incorporation, modelled via an autocatalytic mechanism and mediated by a distorted 2 : 1‐EB2 : Na+ complex. K+ (and Cs+) leads to a direct but less efficient insertion into membranes due to the adoption of "ideal" EB2 : K+ sandwich complexes. In contrast, the presence of Li+, Mg2+, and Ca2+ causes a (partial) extraction of EB from the membrane via the formation of "belted" 1 : 1‐EB : Mz+ complexes, which screen the cationic charge less efficiently. Our results point to a relevance of the cation dependence for the transport into the malignant cells where the mitochondriotoxic anticancer activity is exerted. [ABSTRACT FROM AUTHOR]

Green synthesis of Ag nanoparticles (AgNPs) by using the plant extract is a very important strategy to gain efficient antimicrobial agents with strong antimicrobial activity and low toxicity. In this study, jujube seed extract (JSE) is utilized to green synthesis of AgNPs by both hydrothermal process and solution‐based approaches. UV–vis absorption spectroscopy and infrared spectroscopy (FTIR) spectra confirm that jujube seed extract functionalized Ag nanoparticles are formed by both approaches and jujube seed extract covered on the surface of Ag nanoparticles. Transmission electron microscopy (TEM) images indicate that the JSE‐AgNPs are spherical with the average diameter of 17.7 and 14.2 nm for the hydrothermal process and solution‐based approaches, respectively. X‐ray diffraction (XRD) results indicate that the JSE‐AgNPs prepared by both approaches have face‐centered cubic crystal structure. The antimicrobial activity test reveals that minimum inhibitory concentrations (MIC) of JSE‐AgNPs by the solution‐based method are 62.5, 125, and 62.5 µg mL−1 against Escherichia coli, Staphylococcus aureus, and Candida albicans, respectively. These results imply that the JSE‐AgNPs have potential to be developed as efficient antimicrobial agents. [ABSTRACT FROM AUTHOR]

To satisfy the marking demand for microwave absorbing devices, we design an ultra-broadband nearly perfect absorber. The proposed absorber demonstrates absorption band from long to very long-wavelength ranges (15.7–37.9 µm). An average absorption efficiency of 95.16% and a satisfactory absorption bandwidth of 19.2 µm are achieved. The absorption with high absorptivity and large bandwidth is achieved through combined propagating surface plasmon (PSP) resonances in two directions and localized surface plasmon (LSP) resonances. By simulating and calculating the absorptivity, we demonstrate that the absorber possesses the properties of polarization independence and incident angle insensitivity. When the incident angle reaches 60°, the device still maintains a high absorptivity. Finally, the manufacturing process is illustrated, using radio frequency sputtering with dual guns or an E-beam. Compared with other related microwave absorbers, the proposed absorber balances the contradiction between absorption bandwidth and average absorption. We have strong confidence that the absorber has tremendous applications in many areas, such as infrared thermal emitters, imaging, and photodetectors. [ABSTRACT FROM AUTHOR]

Context: Single-wall carbon nanotubes (SWCNT) dispersed in water with the help of sodium dodecyl sulfate (SDS) surfactants exhibit a temperature dependent near infrared (NIR) exciton spectrum. Due to their biocompatibility and NIR spectrum falling within the transparent window for biological tissue, SWCNTs hold potential for sensing temperature inside cells. Here, we seek to elucidate the mechanism responsible for this temperature dependence, focusing on changes in the water coverage of the SWCNT as the surfactant structure changes with temperature. We compare optical absorption spectra in the UV–Vis-IR range and fully atomistic molecular dynamics (MD) simulations. The observed temperature dependence of the spectra for various SWCNTs may be attributed to changes in the dielectric environment and its impact on excitons. MD simulations reveal that the adsorbed SDS molecules effectively shield the SWCNT, with ~ 70% of water molecules removed from the first two adlayers; this coverage shows a modest temperature dependence. Although we are not able to directly demonstrate how this influences the NIR spectrum, this represents a potential pathway given the strong influence of the water environment on the excitons in SWCNTs. Methods: Optical absorption measurements were carried out in the UV–Vis-NIR range using a Varian Cary 5000 spectrophotometer in a temperature-controlled environment. PeakFit™ v. 4.06 was used as peak-fitting program in the spectral range 900–1400 nm (890–1380 meV) as a function of the temperature. Fully atomistic molecular dynamics simulations were conducted using the NAMD2 package. The CHARMM force field comprising two-body bond stretching, three-body angle deformation, four-body dihedral angle deformation, and nonbonded interactions (electrostatic and Lennard–Jones 6–16 potentials) was employed. [ABSTRACT FROM AUTHOR]

The infrared spectral characteristics of organic‐rich acid residues prepared from Ryugu samples returned by the JAXA Hayabusa2 mission generally match those from unheated carbonaceous chondrite meteorites, but the residues from Ryugu are richer in methyl and methylene functional groups and have higher CH2/CH3 ratios. Moreover, two distinct outlier carbonaceous phases are found; one with spectral characteristics of N‐H functional groups, likely amides, and a second phase containing less nitrogen. Such infrared characteristics of Ryugu organic matter might indicate the pristine nature of the freshly collected samples and reflect the near‐surface chemistry in the parent asteroid. [ABSTRACT FROM AUTHOR]

Modern society's keen regard for aesthetics made hair products an integral part of a multi‐billion‐dollar cosmetic industry. Hair care products (e.g., shampoos and conditioners) and chemical treatments (e.g., bleaching and permanent waving) result in various effects on the morphological attributes of hair. Generally, water adsorbed on the hair surface is known to significantly dictate the hair's mechanical characteristics (smoothness and friction), and hair's macroscopic wettability has been commonly used to indicate its surface properties. However, an approach to selectively characterize the hydration water in the hair surface is required to accurately understand the intermolecular events between the hair and its vicinal water. In this paper, we successfully obtained the infrared (IR) absorption spectra of the hydration water of human hair. We employed the multivariate curve resolution‐alternating least square (MCR‐ALS) method to separate the hydration and bulk water spectra from the whole spectra. Comparing the IR spectra of the hydration water of chemically untreated and bleached hair samples, we conclude that water molecules form strong hydrogen bonds with the bleached hair surface due to the destruction of the hair's hydrophobic outer layer and the consequent formation of hydrophilic residues. [ABSTRACT FROM AUTHOR]

Despite the extensive research conducted on the antimony borate glasses, further investigation is required to explore their structural characteristics when Sb2O3 replaces B2O3 in the presence of rare-earth metal oxide. Herein, the structure and properties of xSb2O3·(99-x)B2O3·1Tb4O7 (30 ≤ x ≤ 70 mol%) were investigated. The infrared (IR) spectra exhibited that there is a remarkable increase in the relative area of the absorption 800–1200 cm−1 region. This is associated with nearly constant density values, despite the heavier Sb2O3 replacing the lighter B2O3. While the molar volume is decreased with the Sb2O3 content, the oxygen packing density is decreased. These findings are related to the structural units belonging to Sb2O3. The type of these units depends on the oxidation of Sb3+ into Sb5+ through the supply of oxygen atoms from the surroundings at high melting temperatures. While Sb3+ acts as a glass network former ion through the formation of [SbO3E] and/or [SbO4E−] (where E is the 5s2 lone-pair of electrons), Sb5+ acts as a modifier ion to convert [SbO3E] into [SbO4E−] units through the formation of [SbO6], similarly to the conversion of [BO3] into [BO4̅] in B2O3 glasses. These structural units are likely contributing to the FTIR absorption 800–1200 cm−1 region, such that its relative area is considered to be the sum of the four-coordinated B atoms [BO4−] (N4) and four-coordinated Sb atoms [SbO4E−] (Sb4). These negative units compensate for the positive terbium ions (Tb3+), thus generating single-doped green phosphor for light-emitting-diode (LED) applications. [ABSTRACT FROM AUTHOR]

Current research on radar and infrared dual stealth in dense Si 3 N 4 -based ceramic materials is limited. This study investigates the influence of carbon nanotubes (CNTs) on the composition, microstructure, electromagnetic wave absorption (EMA) capabilities, and infrared emissivity of hot-pressed Si 3 N 4 -based ceramics. The addition of CNTs resulted in the formation of numerous heterogeneous interfaces and the CNTs conductive network, initially enhancing the ceramics' EMA capabilities before gradually decreasing. Si 3 N 4 -based ceramics loaded with 0.5 wt% and 1 wt% CNTs exhibited significant EMA capabilities, with a minimum refection loss of −60.95 dB at thickness of 7.49 mm. However, with an increase in CNT content, the increasing heterogeneous interfaces and pores in ceramics enhanced the absorption of the electromagnetic wave in the infrared band, resulting in a rise in total infrared emissivity from 0.584 to 0.679. To optimize radar and infrared stealth performance, a two-layered structure can be designed, with Si 3 N 4 and Si 3 N 4 /CNT ceramics serving as the outermost and second layers, respectively. This study provides a way to design high density Si 3 N 4 -based ceramics with infrared and radar stealth. [ABSTRACT FROM AUTHOR]

The development of high-quality phosphor ceramics with high photoelectric efficiencies and thermal stabilities is essential for realizing high-power broadband near-infrared light sources. In this study, a series of pure-phase Gd 3 Sc 2 Al 3 O 12 :Cr3+ near-infrared (NIR) phosphor ceramics (GdScCr NIR-PCs) exhibiting remarkable thermal stability and broadband emission were fabricated for the first time using a vacuum sintering technique. The integrated emission intensity at 423 K is 79.8 % of that at room temperature. The GdSc08Cr exhibits an emission peak at a wavelength of 785 nm, with a full width at half maximum (FWHM) of 116.9 nm under 460 nm excitation. By integrating the GdScCr NIR-PC with a blue light-emitting diode/laser diode (LED/LD) excitation source, the NIR LED prototype achieved a maximum output power of 112.19 mW at 300 mA with a photoelectric conversion efficiency of 13.64 % at 150 mA, and the NIR LD prototype achieved a maximum power output of 484.34 mW at 2.3 A. The operating temperatures of NIR-PCs were 73.1 °C at 300 mA for LED and 90.7 °C at 2.5 A for LD. Moreover, the application of the prepared GdScCr NIR-PCs for fruit and grain detection was performed. These results demonstrate that the prepared GdScCr NIR-PCs possess substantial potential for application in high-power broadband NIR spectroscopy. [ABSTRACT FROM AUTHOR]

In this paper, synthetically scaled-up degenerately n-type doped indium tin oxide (Sn:In2O3) nanocrystals are described as highly transparent conductive materials possessing both optoelectronic and crystalline properties. With tin dopants serving as n-type semiconductor materials, they can generate free-electron carriers. These free electrons, vibrating in resonance with infrared radiation, induce strong localized surface plasmon resonance (LSPR), resulting in efficient infrared absorption. To commercialize products featuring Sn:In2O3 with localized surface plasmon resonance, a scaled-up synthetic process is essential. To reduce the cost of raw materials during synthesis, we aim to proceed with synthesis in a large reactor using industrial raw materials. Sn:In2O3 can be formulated into ink dispersed in solvents. Infrared-absorbing ink formulations can capitalize on their infrared absorption properties to render opaque in the infrared spectrum while remaining transparent in the visible light spectrum. The ink can serve as a security ink material visible only through infrared cameras and as a paint absorbing infrared light. We verified the transparency and infrared absorption properties of the ink produced in this study, demonstrating consistent characteristics in scaled-up synthesis. Due to potential applications requiring infrared absorption properties, it holds significant promise as a robust platform material in various fields. [ABSTRACT FROM AUTHOR]

Copyright of Acta Edulis Fungi is the property of Acta Edulis Fungi 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.)

Current commercial shortwave infrared (SWIR) photodetectors typically necessitate deep cooling to mitigate random fluctuations induced by carrier thermal excitation. Developing high‐sensitivity SWIR photodetectors operating at room temperature is imperative for reducing equipment size and operational expenses. Leveraging the channel depletion mechanism of 2D semiconductors holds promise in suppressing dark current. Another concern lies in the limited choice of infrared absorbing materials and the difficulty in flexibly adjusting the response wavelength region. Here, a high‐sensitive exceptionally low‐noise SWIR photodetector operated is reported at room temperature based on few‐layer WSe2/TCNQ molecules charge transfer complex. Experiments and Calculations results exhibit the low‐frequency (0.6 eV) SWIR absorption stems from the intermolecular charge transfer transition at the interface of heterojunctions. The hybrid photodetector can achieve response efficiently from visible to SWIR (0.6–1.6 µm) with a decent gain 7.7 × 104 and an ultralow dark current noise spectral density (Sn) 1.95 × 10−16 A/Hz0.5 under a channel deplete state at room temperature. The peak specific detectivity is 2.5 × 1013 Jones at 0.7 µm and 7.4 × 1012 Jones at 1.2 µm, (Vgs = 80 V). This work has opened up a new pathway for the development of high‐sensitivity SWIR photodetectors at room temperature. [ABSTRACT FROM AUTHOR]

Controlled dispersal of microfliers over large‐scale areas is crucial for both civil and agricultural applications. Until now, the study of flying soft actuators is limited by the complexity of the motion involved and with control when miniaturized to a micro‐scale. Drawing inspiration from the dynamics of dandelion seed spread, the study proposes a novel design for a flying soft actuator comprising Ti3C2Tx MXene and polyethylene (PE), which exhibits sensitive responses to various stimuli, including humidity, temperature, applied voltage, infrared light, and selective volatile organic compounds, leading to significant deformation at a rapid rate (up to 81.82°/s). An artificial seed capable of wind‐assisted flight is further fabricated by integrating a MXene/PE actuator with fiberglass. When exposed to light, the artificial seed opens its fiberglass pappus during descent, increasing resistance and thereby prolonging falling time by an impressive 83%. Moreover, the artificial seed demonstrates self‐sensing, i.e., changes in resistance caused by humidity and infrared light, which can be attributed to the absorption and desorption of water molecules within MXene layers. This enhanced falling time enables a wider dispersal range and precise control, making it highly promising for environmental monitoring, automated large‐scale sensor deployments, and large‐scale seed sowing for endangered plants species protection. [ABSTRACT FROM AUTHOR]

A label-free one-step lithographically masked deposition technique was implemented for the fabrication of gold nanoparticle (Au NP) micropatterns. These micropatterns serve as active substrates for surface-enhanced infrared absorption spectroscopy (SEIRAS) and exhibit a substantial increase in the IR signal upon adsorption of multiple proteins compared to untreated surfaces. Micro-FTIR chemical imaging was conducted to evaluate the efficacy of Au NP micropatterns as singular enhancers for SEIRAS across diverse IR-active substrates demonstrating a promising application for the detection of proteins at low concentrations within biological fluids. [ABSTRACT FROM AUTHOR]

Data from the Operational Land Imager (OLI) and the Thermal Infrared Sensor (TIRS) instruments onboard the Landsat 8 and Landsat 9 satellite platforms are subject to contamination by cloud cover, with cirrus contributions being the most difficult to detect and mask. To help address this issue, a cirrus detection channel (Band 9) centered within the 1.375-μm water vapor absorption region was implemented on OLI, with a spatial resolution of 30 m. However, this band has not yet been fully utilized in the Collection 2 Landsat 8/9 Level 2 surface temperature data products that are publicly released by U.S. Geological Survey (USGS). The temperature products are generated with a single-channel algorithm. During the surface temperature retrievals, the effects of absorption of infrared radiation originating from the warmer earth's surfaces by ice clouds, typically located in the upper portion of the troposphere and re-emitting at much lower temperatures (approximately 220 K), are not taken into consideration. Through an analysis of sample Level 1 TOA and Level 2 surface data products, we have found that thin cirrus cloud features present in the Level 1 1.375-μm band images are directly propagated down to the Level 2 surface data products. The surface temperature errors resulting from thin cirrus contamination can be 10 K or larger. Previously, we reported an empirical and effective technique for removing thin cirrus scattering effects in OLI images, making use of the correlations between the 1.375-μm band image and images of any other OLI bands located in the 0.4–2.5 μm solar spectral region. In this article, we describe a variation of this technique that can be applied to the thermal bands, using the correlations between the Level 1 1.375-μm band image and the 11-μm BT image for the effective removal of thin cirrus absorption effects. Our results from three data sets acquired over spatially uniform water surfaces and over non-uniform land/water boundary areas suggest that if the cirrus-removed TOA 11-μm band BT images are used for the retrieval of the Level 2 surface temperature (ST) data products, the errors resulting from thin cirrus contaminations in the products can be reduced to about 1 K for spatially diffused cirrus scenes. [ABSTRACT FROM AUTHOR]

An arrayed nanocavity-shaped architecture consisting of the key GdFe film and SiO2 dielectric layer is constructed, leading to an efficient infrared (IR) absorption metasurface. By carefully designing and optimizing the film system configuration and the surface layout with needed geometry, a desirable IR radiation absorption according to the spatial magnetic plasmon modes is realized experimentally. The simulations and measurements demonstrate that GdFe-based nanocavity-shaped metasurfaces can be used to achieve an average IR absorption of ~81% in a wide wavelength range of 3–14 μm. A type of the patterned GdFe-based nanocavity-shaped metasurface is further proposed for exciting relatively strong spatial electromagnetic wavefields confined by a patterned nanocavity array based on the joint action of the surface oscillated net charges over the charged metallic films and the surface conductive currents including equivalent eddy currents surrounding the layered GdFe and SiO2 materials. Intensive IR absorption can be attributed to a spatial electromagnetic wavefield excitation and resonant accumulation or memory residence according to the GdFe-based nanocavity-shaped array formed. Our research provides a potential clue for efficiently responding and manipulating and storing incident IR radiation mainly based on the excitation and resonant accumulation of spatial magnetic plasmons. [ABSTRACT FROM AUTHOR]

Intrinsic silicon (Si) is forbidden for infrared (IR) sensing at the communication wavelength like 1.31 or 1.55 µm due to the well‐known bandgap limitation. In this work, an unexpected physical picture of using argon (Ar) is identified, which is usually inert to the surrounding chemical environment and used as a protective agent in semiconductor processing, to overcome the IR‐sensing‐forbidden problem in Si. Here, it is shown by an analysis of a dynamic secondary ion mass spectrometer that such a Si, when exposed to laser pulse in Ar gas, can contain a very high dose of Ar up to 1020 cm−3 even after 1300 days. First‐principles calculations, molecular dynamics, and Hall effect measurements reveal that, due to both steric and dynamic repulsions by Ar orbitals to Si dangling bonds, the Ar‐filled‐vacancy produces a much wider defect band inside the gap, which is not only responsible for strong infrared absorption, but also causes a significant increase in n‐type conductivity, both in line with experiments. The study proves that originally inert elements in fact can act as active impurities in semiconductors for advanced applications, which updates the current knowledge of defect physics. [ABSTRACT FROM AUTHOR]

Copyright of Shipin Kexue/ Food Science is the property of Food Science Editorial Department 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.)

This Letter details a pioneering study on the design and nanofabrication process of a thermoelectric infrared radiation detector using a suspended polyimide membrane. The research includes a comprehensive analysis of thermoelectric doped Bi2Te3 thin films, comparing their expected performance regarding noise and specific detectivity with other infrared detectors, particularly those in the silicon sector. Experimental results and calculations shed light on responsivity and time constants. In the absence of absorption layers, specific detectivity values for visible and near infrared radiation are measured at 9.2 × 107 and 2.9 × 107 cm Hz / W , respectively, with a time constant nearing 20 ms. Calculations show that introducing an optimized absorption layer with ε = 1 significantly improves specific detectivity, reaching 9.0 × 108 cm Hz / W. Subsequent calculations also show that further enhancement can be obtained by etching the polyimide membrane to a 1-micron thickness, resulting in an exceptional specific detectivity value of 8.4 × 109 cm Hz / W , placing it among the best in the current state-of-the-art. [ABSTRACT FROM AUTHOR]

Electrochemical CO2 reduction reaction (CO2RR) offers a sustainable strategy for producing fuels and chemicals. However, it suffers from sluggish CO2 activation and slow water dissociation. In this work, we construct a (P−O)δ− modified In catalyst that exhibits high activity and selectivity in electrochemical CO2 reduction to formate. A combination of in situ characterizations and kinetic analyses indicate that (P−O)δ− has a strong interaction with K+(H2O)n, which effectively accelerates water dissociation to provide protons. In situ attenuated total reflectance surface‐enhanced infrared absorption spectroscopy (ATR‐SEIRAS) measurements together with density functional theory (DFT) calculations disclose that (P−O)δ− modification leads to a higher valence state of In active site, thus promoting CO2 activation and HCOO* formation, while inhibiting competitive hydrogen evolution reaction (HER). As a result, the (P−O)δ− modified oxide‐derived In catalyst exhibits excellent formate selectivity across a broad potential window with a formate Faradaic efficiency as high as 92.1 % at a partial current density of ~200 mA cm−2 and a cathodic potential of −1.2 V vs. RHE in an alkaline electrolyte. [ABSTRACT FROM AUTHOR]

A planar conjugated ligand functionalized with bithiophene and its Ru(II), Os(II), and Ir(III) complexes have been constructed as single‐molecule platform for synergistic photodynamic, photothermal, and chemotherapy. The complexes have significant two‐photon absorption at 808 nm and remarkable singlet oxygen and superoxide anion production in aqueous solution and cells when exposed to 808 nm infrared irradiation. The most potent Ru(II) complex Ru7 enters tumor cells via the rare macropinocytosis, locates in both nuclei and mitochondria, and regulates DNA‐related chemotherapeutic mechanisms intranuclearly including DNA topoisomerase and RNA polymerase inhibition and their synergistic effects with photoactivated apoptosis, ferroptosis and DNA cleavage. Ru7 exhibits high efficacy in vivo for malignant melanoma and cisplatin‐resistant non‐small cell lung cancer tumors, with a 100 % survival rate of mice, low toxicity to normal cells and low residual rate. Such an infrared two‐photon activatable metal complex may contribute to a new generation of single‐molecule‐based integrated diagnosis and treatment platform to address drug resistance in clinical practice and phototherapy for large, deeply located solid tumors. [ABSTRACT FROM AUTHOR]

Increasing concerns about air quality due to fossil fuel combustion, especially nitrogen oxides (NOx) from marine and diesel engines, necessitate advanced monitoring systems due to the significant health and environmental impacts of nitrogen dioxide (NO2). In this study, a gas detection system based on the principle of the non-dispersive infrared (NDIR) technique is proposed. Firstly, the pyroelectric detector was developed by employing an ultra-thin LiTaO3 (LT) layer as the sensitive element, integrated with nanoscale carbon material prepared by wafer-level graphics technology as the infrared absorption layer. Then, the sensor was hermetically sealed using inert gas through energy storage welding technology, exhibiting a high detectivity (D*) value of 4.19 × 108 cm·√Hz/W. Subsequently, a NO2 gas sensor was engineered based on the NDIR principle employing a Micro Electro Mechanical System (MEMS) infrared (IR) emitter, featuring a light path chamber length of 1.5 m, along with integrated signal processing and software calibration algorithms. This gas sensor was capable of detecting NO2 concentrations within the range of 0–500 ppm. Initial tests indicated that the gas sensor exhibited a full-scale relative error of less than 0.46%, a limit of 2.8 ppm, a linearity of −1.09%, a repeatability of 0.47% at a concentration of 500 ppm, and a stability of 2% at a concentration of 500 ppm. The developed gas sensor demonstrated significant potential for application in areas such as industrial monitoring and analytical instrumentation. [ABSTRACT FROM AUTHOR]

Allan–Werle-plots are an established tool in infrared absorption spectroscopy to quantify temporal stability, maximum integration time and best achievable precision of a measurement instrument. In field measurements aboard a moving platform, however, long integration times reduce time resolution and smooth atmospheric variability. A high accuracy and time resolution are necessary as well as an appropriate estimate of the measurement uncertainty. In this study, Allan-Werle-plots of calibration gas measurements are studied to analyze the temporal characteristics of a Quantum Cascade Laser Absorption Spectrometer (QCLAS) instrument for airborne operation. Via least-squares fitting the individual noise contributions can be quantified and different dominant regimes can be identified. Through simulation of data according to the characteristics from the Allan-Werle-plot, the effects of selected intervals between in-flight calibrations can be analyzed. An interval of 30 min is found sufficient for successful drift correction during ground operation. The linear interpolation of the sensitivity increases the accuracy and lowers the measurement uncertainty from 1.1 % to 0.2 % . Airborne operation yields similar results during segments of stable flight but suffers from additional flicker and sinusoidal contributions. Simulations verify an appropriate interval of 30 min in airborne operation. The expected airborne measurement uncertainty is 2.45 ppbv. [ABSTRACT FROM AUTHOR]

Ultra-broadband metamaterial absorbers (UBMAs) that are compatible with CMOS technology for use in the mid-infrared and long-wave infrared regions are crucial for a variety of applications, including radiative cooling, thermal photovoltaic, and thermal imaging. In this regard, we propose, in this work, a design of an UBMA based on the heavily doped silicon (D-Si) and silicon carbide (SiC). The 3D finite-difference time-domain method is used, mainly, to numerically calculate the optical characteristics of the proposed UBMA. The absorber, which is made up of a periodic array of symmetrical multilayered square rings of D-Si and SiC, achieves high absorption with an average absorption of 95% over a wavelength range of 2.5–22 µm. This broad range of wavelength absorption is attained, encompassing the mid-, long-wave, and partial far-infrared regions. In addition to the materials' inherent absorption, the stimulation of magnetic polaritons, surface plasmon polaritons, localized surface plasmon resonance, and cavity resonance are responsible for the nearly perfect broadband absorption. Under normal incidence, the proposed UBMA is polarization-independent due to the symmetrical design of the absorber. Furthermore, the impact of the incidence angle on the absorption of transverse electric and transverse magnetic waves is examined. [ABSTRACT FROM AUTHOR]

A type of nanocavity-shaped metasurface for intensively absorbing infrared (IR) radiation in a wide wavelength range of 3–14 μm, which is mainly based on spatial magnetic plasmon excitation and accumulation according to an arrayed nanocavity, is proposed. The basic architecture of the metasurfaces is a layered metal-insulator-metal construction through linear arranging of titanium microribbons and also forming an arrayed titanium microcap on the top of a SiO2 layer preshaped over a thin copper film grown on an n-type silicon wafer, respectively. The measurements present that an average IR absorbing efficiency of more than ∼80% can be easily realized by the metasurfaces constructed. The microribbon-based metasurface exhibits polarization sensitivity under x-polarized incidence. A polarization-independent IR absorption can be conducted through the microcap-based metasurface developed continuously. It should be noted that the proposed nanocavity-shaped metasurfaces can, thus, be featured by an intensive IR absorption essentially attributed to the spatial magnetic plasmon excitation and accumulation or a spatial magnetic field resonant superposition and temporary storage in the multiple nanocavities of the metasurfaces designed. [ABSTRACT FROM AUTHOR]

We designed a metamaterial far-infrared absorber based on an MDM (metal–dielectric–metal) structure. We made a hollow crossed Ti microstructure at the top of the absorber. It is known that the coupling effect of equipartitional exciton resonance and intrinsic absorption at the surface of the depleting material has a strong influence on the absorber. Based on this, we investigated the absorption characteristics of the absorber using the Finite Difference in Time Domain (FDTD) theory. The results show that the absorber absorbed more than 90% of the light within a bandwidth of 12.01 μm. The absorber has an average absorption of 94.08% in the longwave infrared (LWIR) to ultra-longwave infrared (UWIR) bands (10.90–22.91 μm). The polarization insensitivity of the designed absorber is demonstrated by analyzing the absorption spectra of the absorber at different polarization angles. By adjusting the relevant geometric parameters, the absorption spectrum can be independently adjusted. Furthermore, the absorber exhibits good incidence angle insensitivity in both transverse electric (TE) and transverse magnetic (TM) modes. The absorbers are simple and easy to configure for applications such as optical cloaking, infrared heat emitters, and photodetectors. These advantages will greatly benefit the application of absorbers in practice. [ABSTRACT FROM AUTHOR]