IR Signal Research Articles

A novel method to calibrate a fast IR-measurement system by utilizing the temperature dependence of oxide layers

Laser material processing by pulsed lasers is an effective method for realizing a variety of temperature-critical processes. Through appropriate parameter selection and processing strategies, micro-structuring can be used to functionalize material surfaces. One of these functionalization is the defined tempering of metallic surfaces to generate annealing colors. By locally heating the surface an oxide layer is formed that produces a specific color when exposed to light. This resulting color depends on its oxide layer thickness, which is determined by the temperature. Commonly this process is referred as laser coloring. In our present work we developed a new calibration method for a fast IR-emission measuring setup by utilizing the temperature dependence of the oxide layer. By using fast IR-detectors during laser coloring, it is possible to assign each measured IR signal to the resulting color and its corresponding temperature of the oxide layer, allowing a conversion to absolute temperatures.

Impact of UV radiation on the Raman and infrared spectral signatures of sulfates, phosphates and carbonates: Implications for Mars exploration

Perseverance is on Mars, collecting samples which will inform about Martian geology and paleoenvironmental conditions. However, the surface of Mars is continuously bombarded by ionizing and non-ionizing radiation, including UVs, which may significantly alter hydrated mineral phases such as sulfates, phosphates and carbonates. To explore and constrain this effect, we experimentally exposed pellets of more or less hydrated minerals to UV radiation within a Martian chamber at a temperature relevant for the rocks at the surface of Mars. Results show that exposure to UV leads to a strong alteration of the Raman and IR signals of sulfates, phosphates and carbonates. The strong increase of the luminescence signals coupled to the decrease of the Raman signals relatively to the background and the clear attenuation of the IR signals are interpreted as caused by an increasing concentration of electronic defects. The present results have major implications for the ongoing exploration of Mars: one should not expect to detect pristine materials, except over freshly excavated surfaces. Still, as a precaution, all the targets measured or collected on Mars should be considered as having been exposed to UV radiation to some extent.

Rapid discrimination of Lentilactobacillus parabuchneri biofilms via in situ infrared spectroscopy

Microbial contamination in food industry is a source of foodborne illnesses and biofilm-related diseases. In particular, biogenic amines (BAs) accumulated in fermented foods via lactic acid bacterial activity exert toxic effects on human health. Among these, biofilms of histamine-producer Lentilactobacillus parabuchneri strains adherent at food processing equipment surfaces can cause food spoilage and poisoning. Understanding the chain of contamination is closely related to elucidating molecular mechanisms of biofilm formation. In the present study, an innovative approach using integrated chemical sensing technologies is demonstrated to fundamentally understand the temporal behavior of biofilms at the molecular level by combining mid-infrared (MIR) spectroscopy and fluorescence sensing strategies. Using these concepts, the biofilm forming capacity of six cheese-isolated L. parabuchneri strains (IPLA 11151, 11150, 11129, 11125, 11122 and 11117) was examined. The cut-off values for the biofilm production ability of each strain were quantified using crystal violet (CV) assays. Real-time infrared attenuated total reflection spectroscopy (IR-ATR) combined with fluorescence quenching oxygen sensing provides insight into distinct molecular mechanisms for each strain. IR spectra showed significant changes in characteristic bands of amides, lactate, nucleic acids, and extracellular polymeric substances (i.e., lipopolysaccharides, phospholipids, phosphodiester, peptidoglycan, etc.), which are major contributors to biofilm maturation involved in the initial adhesion processes. Chemometric methods including principal component analysis and partial least square-discriminant analysis facilitated the rapid determination and classification of cheese isolated L. parabuchneri strains unambiguously differentiating the IR signatures based on their ability to produce biofilm. All biofilms were morphologically characterized by confocal laser scanning microscopy on relevant industrial equipment surfaces. In summary, this innovative approach combining MIR spectroscopy with luminescence sensing enables real-time insight into the molecular composition and formation of L. parabuchneri biofilms.

Dual-band absorption due to simultaneous excitation of TE and TM modes in ITO-ES metamaterial for IR stealth technology

We proposed a plasmonic based Indium Tin Oxide Embedded Silver (ITO-ES) infrared dual-band perfect absorber for the utilization in IR stealth technology. The proposed structure comprised of nano size Ag ring and desk embedded in ITO. The optical losses in optical regime of nanoscale plasmonic Ag were incorporated in terms of collision frequency using the modified Drude model. The optical response of the proposed structure was predicted by exciting it with a planwave using full wave vector frequency domain solver by employing Finite Element Method (FEM) in Computer Simulation Technology (CST) Microwave Studio. The simultaneous excitation of higher order transverse electromagnetic (TE and TM) modes in the proposed structure lead to high values of both absorption and Front to Back ratio (FTBR). The controlled and selective wavelength multiband absorption is crucial for IR stealth technology. The proposed metamaterial structures exhibit dual-bands IR absorption at wavelengths λ = 1.40 μm and 6.4 μm. First absorption peak suppresses the back scattering of the laser used by laser guided devices for detection, while the second peak suppresses the IR signature of the structure due thermal radiation which can be used by tracking devices to detect warm/hot objects.

Adaptive long wave-infrared camouflage using an all-dielectric metasurface

All-dielectric metamaterials consisting of high-index, sub-wavelength, and periodically decorated arrays allow for efficient manipulation of electromagnetic permittivity and permeability with lower losses at the optical frequencies. In this study, we propose a planar multilayer structure composed of dielectric interlayers (Al2O3/Ge/ITO/Soda Lime Glass) to achieve perfect and broadband absorption of mid- and long-infrared (IR) wavelengths. Analyzing the spectral properties of the designed structure proved that it possesses exquisite importance in thermal application when considering the IR signature reduction in the long wavelength range, as well as the reduced radiated energy dissipation along with the undetected band and the requirements for IR camouflage. This intrinsic merit of dielectric metamaterials stems from their inherent selective absorption/emission. In that respect, Kirchhoff's law states that the emissive and absorptive powers of all bodies are similar for radiation of the same wavelength at the same temperature. The temperature difference may occur not only from the properties of the surfaces but also from the optical properties of materials and environmental conditions. Studying the thermal camouflage at different background temperatures found that the camouflage material substantially reduces the contrast between the target and the background. Beyond that, extensive assessments validated that the contrast in the resulting short tips is due to the differences in the reflective properties of the material and the background. Our simulations and experiments lay the groundwork for structuring cost-effective all-dielectric thermal camouflage metaplatforms with high performance and the strong potential to be employed in practical military and defense applications.

Naphthaldehyde-Based Schiff Base Chemosensor for the Dual Sensing of Cu2+ and Ni2+ Ions.

In this study, a simple Schiff base sensor 1-(((4-nitrophenyl)imino)methyl)naphthalen-2-ol(NNM) has been used for chemosensing of metal ions. The metal sensing properties of sensor NNM have been investigated using UV-visible and fluorescence spectroscopic approaches. The spectral investigations revealed a red shift in absorption spectra and quenching in the emission band of the ligand molecule in the presence of Cu2+ and Ni2+ ions. The binding stoichiometry of sensor NNM for the analyte (Cu2+ and Ni2+ ions) has been investigated by the Job's plot analysis and found to be 1:1 (NNM:Analyte). The data of the Benesi-Hildebrand plot demonstrated that NNM detected Cu2+ and Ni2+ ions in nanomolar quantity. The binding insights among NNM and analytes (Cu2+ and Ni2+ ions) have been confirmed by shifted IR signals. Moreover, the reusabilty of the sensor has been investigated using an EDTA solution. In addition, the sensor NNM also successfully applied to real water samples for the identification and measurement of Cu2+ and Ni2+ ions. Hence, this system could be highly applicable in environmental and biological applications.

Congestion Management System for Emergency Vehicles using AT89S52

Emergency vehicles face challenges when navigating congested roads, which can lead to delayed response time and decreased effectiveness in emergency situations. This paper presents a congestion management system for emergency vehicles using the AT89S52 microcontroller. The system uses real-time traffic data to dynamically adjust traffic signals and create an efficient path for emergency vehicles. The proposed system was tested and evaluated using simulation software, and the results demonstrate a significant reduction in response time for emergency vehicles in congested areas. In this project we are going to use IR communication to analyze traffic density. IR signals from IR receiver are given to microcontroller and microcontroller gives appropriate result according to traffic. For emergency vehicle congestion clearance, we use RFID transmitter for specific lane clearance, while RFID receiver remains active in the circuit. When RFID vehicle is detected, the lane gets the highest priority and its signal turns green, for congestion clearance. This model is very effective in metropolitan cities, urban cities or cities where high traffic is found at junctions

ATP binding and ATP hydrolysis in full-length MsbA monitored via time-resolved Fourier transform infrared spectroscopy.

The essential Escherichia coli ATPase MsbA is a lipid flippase that serves as a prototype for multi drug resistant ABC transporters. Its physiological function is the transport of lipopolisaccharides to build up the outer membranes of Gram-negative bacteria. Although several structural and biochemical studies of MsbA have been conducted previously, a detailed picture of the dynamic processes that link ATP hydrolysis to allocrit transport remains elusive. We report here for the first time time-resolved Fourier transform infrared (FTIR) spectroscopic measurements of the ATP binding and ATP hydrolysis reaction of full-length MsbA and determined reaction rates at 288 K of k 1=0.49±0.28 s-1 and k 2=0.014±0.003 s-1, respectively. We further verified these rates with photocaged NPEcgAppNHp where only nucleotide binding was observable and the negative mutant MsbA-H537A that showed slow hydrolysis (k 2<2×10-4 s-1). Besides single turnover kinetics, FTIR measurements also deliver IR signatures of all educts, products and the protein. ADP remains protein-bound after ATP hydrolysis. In addition, the spectral changes observed for the two variants MsbA-S378A and MsbA-S482A correlated with the loss of hydrogen bonding to the γ-phosphate of ATP. This study paves the way for FTIR-spectroscopic investigations of allocrite transport in full-length MsbA.

Espresso Science: Laser-Based Diamond Thin-Film Waveguide Sensors for the Quantification of Caffeine.

Diamond thin-film waveguides with a nanocrystalline diamond layer of approximately 20 μm thickness were used in the mid-infrared regime in combination with quantum cascade lasers to detect the IR signature of caffeine. The diamond thin-film waveguides were fundamentally characterized with respect to their morphological properties via AFM and SEM. Theoretical simulations confirmed the feasibility of using a larger sensing area of approximately 50 mm2 compared to conventionally used strip waveguides. A comprehensive and comparative analysis confirmed the performance of the diamond thin-film-waveguide-based sensing system vs data obtained via conventional attenuated total reflection Fourier transform infrared spectroscopy using a single-bounce diamond internal reflection element. Hence, the utility of innovative diamond thin-film-waveguide-based sensors coupled with quantum cascade laser light sources has been confirmed as an innovative analytical tool, which may be used in a wide range of application scenarios, ranging from environmental to medical sensing, taking advantage of the robustness and inertness of nanocrystalline diamond.

Research on the denoising method of infrared thermogram during rock fracture

In order to overcome the defects of low contrast and low signal-to-noise ratio of the infrared thermal image of rock (ITIR), a joint denoising method of additive and multiplicative noise is proposed for infrared radiation thermal image of rock bearing fracture process. ITIR is de-noised using background phase subtraction, adaptive median filtering, and wavelet multi-scale decomposition threshold denoising Firstly, the noise types in ITIR are analyzed, the basic principles and implementation steps of the denoising method are described, and the denoising effects of different combinations of wavelet basis functions with different decomposition scales in the wavelet threshold denoising process are simulated. Finally, the denoising effect was evaluated in terms of peak signal-to-noise ratio (PSNR), root mean square error (RMSE), and blind/referenceless image spatial quality evaluator (BRISQE). The results show that the PSNR of ITIR is increased by 15.01 % based on removing additive noise. The image quality scores increased by 49.54 % before and after overall denoising. The studies have significance for IR signal extraction and denoising in rocks and solid materials.

Optimization of multispectral chalcogenide glass for large-size fabrication.

Chalcogenide glass has become one of the essential IR lens materials in passively athermalized long-wave IR devices. However, that there is no multispectral chalcogenide glass capable of large-size fabrication raises challenges to the development and popularization of multispectral imaging systems combining visible, near-IR, and mid-IR. In this work, we developed a novel chalcogenide glass capable of a record-big (Ø120 mm) fabrication through the compositional optimization of GeS2-Ga2S3-CsCl glass with introduction of Sb2S3. Its transmission window is characterized as ranging from 0.51 to 11.2 µm, which means it could be employed as a multispectral lens transmitting visible and IR signals in a co-aperture IR optical system. In addition, a method of three-stage thermal analysis is proposed to evaluate the glass-forming ability of chalcogenide glass through simulating the melt-quenching process of chalcogenide melt in a vacuum-sealed silica ampoule. This work not only shows an innovative multispectral chalcogenide glass with promising applications but also introduces a simple and convenient technique for screening chalcogenide glass with ultrahigh glass-forming ability capable of large-size fabrication.

Study the electrical properties of ZnOSiO2 detector prepared by free rappid thermal oxidation

Zinc thin films deposited on (n-type)silicon at 510o C with oxidation times (10,20,30,35) sec have been oxidized. Zinc have been deposited by thermal diffusion method using heater instead of conventional furnace .It is found that we can get zinc oxide with outoxegen and closed farneces rapidly. The electrical properties in dark show that the detector is shottky diode, and the best time to obtain the detector is 35 sec, and the ideality factor is 3.3 with a work function of 0.58 ev. It is found that the resalts at light power (50,100,150,200,250) mw/cm2.Show that the detector oxidiced in 35 sec have detectivity factor 540.8 and have a high responsivity which enable the detector to detect the IR signals.

The bleaching limits of IRSL signals at various stimulation temperatures and their potential inference of the pre-burial light exposure duration

Infrared Stimulated Luminescence (IRSL) techniques are being increasingly used for dating sedimentary feldspars in the middle to late Quaternary. By employing several subsequent stimulations at increasing temperatures, a series of post-IR IRSL (pIRIR) signals with different characteristics (stability and bleachability) can be obtained for an individual sample. It has been experimentally demonstrated that higher-temperature pIRIR signals are more stable, but they tend to exhibit larger residual doses up to few tens of Gy, potentially causing severe age overestimation in young samples. In this study we conducted comprehensive bleaching experiments of IRSL and pIRIR signals using a loess sample from China, and demonstrated that non-bleachable components in the IR (and possibly pIRIR) signals do exist. The level of such non-bleachable signal shows clearly positive correlation with preheat/stimulation temperature, which further supports the notion that lower temperature pIRIR are advantageous to date young samples and sediments especially from difficult-to-bleach environments. These results display a potential in constrain the pre-burial light exposure history of sediment utilizing multiple feldspar post-IR IRSL (pIRIR) signals. For the studied loess sample, we infer that prior to its last burial, the sample has received an equivalent of &amp;gt;264 h exposure to the SOL2 simulator (more than 2,000 h of natural daylight).

Chirality induction and amplification in supramolecular systems exhibiting vibrational optical activity.

Vibrational optical activity (VOA) refers to two vibrational techniques: vibrational circular dichroism (VCD) and Raman optical activity (ROA) that are sensitive both to the chirality and the molecular structure, typically surpassing electronic optical activity (EOA) in recognition of fine structural details. However, the measurement of VOA is inherently obstructed as the intensity of the VOA signal is typically 10-4-10-5 of the intensity of the parent IR or Raman signals. This feature considerably limits the practical applications of VOA and is a fundamental reason why various strategies are currently developed to enhance the VOA intensity. This perspective review discusses up-to-date studies focusing on applications of VOA to analyse supramolecular, mostly biogenic, systems showing induction and amplification of chirality. Most attention is devoted to two types of biogenic supramolecular assemblies providing unique enhancement of VOA: amyloid fibrils showing enormous VCD and carotenoid aggregates exhibiting resonantly enhanced ROA.

In search of the bottlenecks of ammonia synthesis over Ru/Vulcan under ambient conditions.

Hydrogenation of the N-N bond under ambient conditions over 1 wt% Ru/Vulcan was monitored through operando Diffuse Reflectance Infrared Spectroscopy (DRIFTS) and DFT. IR signals centered at 3017 cm-1 and 1302 cm-1 were visible with attributes similar to the asymmetric stretching and bending vibrations of gas phase ammonia at 3381 cm-1 and 1650 cm-1. The intensities of the signals increased with consecutive H2 : Ar and N2 flow cycles at room temperature and atmospheric pressure due to accumulation of the formed NHX on the catalyst surface. DFT estimations revealed that a compound with a molecular stoichiometry of N-NH3 can give rise to an IR signal centered at 3051.9 cm-1. The results of this study, combined with the known vapor liquid phase behavior of ammonia, suggest that under subcritical conditions, the bottlenecks of ammonia synthesis are both N-N bond dissociation and ammonia desorption from the pores of the catalyst.

An ultrafast and self-powered MoSxSe2-x/Si photodetector with high light-trapping structures and a SiOx interface layer.

MoSxSe2-x nanofilms, as a typical metal dichalcogenide, have attracted great interest, due to their adjustable bandgap and distinctive electronic and optical properties. However, the inherent bandgap of MoSxSe2-x and the strong interface recombination impede the actualization of a high-sensitivity photodetector (PD). Few-layer MoSxSe2-x nanofilms were prepared with vertically orientation at 450 °C, which would be a less restrictive choice of substrates. Herein, a self-powered MoSxSe2-x/SiOx/Si photodetector was fabricated which exhibits unprecedented performance with excellent reproducibility and stability from 405 nm to 980 nm, a high responsivity (0.450 A W-1), normalized detectivity (4.968 × 1012 Jones) and ultrafast photoresponse (τr = 1.20 μs, τf = 4.92 μs) at zero bias under 980 nm incident laser illumination with a density of 200 μW cm-2. Significantly, the self-powered PD is capable of detecting ultraweak IR signals below 200 μW cm-2 with high on-off ratios. More importantly, an oxidized atomic layer is generated through the wet oxidation in the Piranha solution. The PD can work well at high frequencies even at 100 kHz, which shows its potential application in high-frequency photoelectric devices and health monitors. Summing up, this work not only suggests that an ultrathin SiOx interface layer can reduce carrier recombination via simple interface engineering, but also proposes a novel strategy for the preparation of high-performance and low-cost optoelectronic devices.

Quantification of Exchanged Copper Species in Cu‐Chabazite Zeolite using Cryogenic Probe Infrared Spectroscopy

AbstractThe development of a low temperature (−160 °C) NO adsorption technique is disclosed that avoids the chemical conversion of the probe molecule at room temperature. The observed IR peaks for Cu+(NO)2 and Cu2+(NO) species can be used to quantify the amount of exchanged copper species in a broad range of samples, including a wash‐coated honeycomb. Calibration curves for Cu+(NO)2 and Cu2+(NO) are determined for copper loadings up to 3.99 wt% with Silica‐to‐Alumina Ratio (SAR) of 16–22, and quantitative agreement with the complementary hydrogen Temperature Programmed Reduction (H2‐TPR) results is established. This methodology allows to identify different Cu species in Cu‐CHA, such as Z2Cu(II), Z1Cu(II)OH and Cu dimers, based on their distinct IR signatures. In addition, the perturbed T−O−T framework vibration – characterized at 400 °C – can also be used as a complimentary method to quantify Z2Cu(II) species.

Coarse-grained K-rich feldspar and fine-grained polymineral IRSL dating of loess-palaeosol from the Chinese Loess Plateau: A comparison

In this study, the characteristics of infrared stimulated luminescence (IRSL) signals from coarse-grained (63–100 μm, CG) K-feldspar and fine-grained (4–11 μm, FG) polymineral fractions was compared using the Chinese loess/palaeosol samples from the Luochuan profile. The pIRIR 50, 225 and pIRIR 200, 290 protocols (pIRIR: post-IR IRSL. The subscript shows stimulation temperatures for the IR and pIRIR signals) were used. Natural signal intensities of eleven samples were used to construct the natural dose-response curve (DRC) for each signal. The laboratory and simulated-natural DRCs for each signal from the CG K-feldspar and FG polymineral fractions were constructed and were compared with the natural DRC. The natural DRCs were broadly consistent for the two pIRIR and the IR 200 signals for both fractions. The characteristic saturation dose ( D 0 ) of the natural DRCs for the pIRIR signals from the CG K-feldspar tended to be smaller than those from the FG polymineral fraction. Conversely, the D 0 s of the laboratory DRCs for all the signals from the CG K-feldspar were larger than those from the FG polymineral fraction. The ratio of simulated-natural DRC over natural DRC (N sim /N) was able to successfully determine the fading over- or under-correction tendencies for different signals and dose regions.

Numerical Investigation of Air Entrainment and Outlet Temperature Characteristics of a Convex-Type Infrared Suppression Device

AbstractInfrared suppression devices (IRS) are frequently used in naval/cargo ships to passively entrain an additional amount of cold air from the atmosphere, and mix it with the hot plume so as to suppress its temperature, and the IR signature. In this work, a convex-type IRS device has been proposed consisting of five numbers of the convex-type funnels. The air entrainment ratio has been numerically computed by solving the transport equations (i.e., mass, momentum, energy, turbulent kinetic energy, and its dissipation rate in a structured grid arrangement by employing a pressure-based finite volume solver in ansysfluent. The pertinent parameters like the Reynolds number, inlet temperature ratio, convex-radius ratio, and funnel-overlap height have been varied in the range of −1.5 × 105 to 1.5 × 106, 1.243 to 2.576, 0.834 to 1, and 0 to 0.326, respectively. It has been observed that the air entrainment ratio increases with both the Reynolds number and convex-radius ratio for the considered temperature ratios. An optimum convex-radius ratio (=0.909) has been obtained, where the air entrainment and the outlet temperature become the maximum and the minimum, respectively. Both the inlet temperature ratio and overlap height significantly improve intake of cold air into the IRS device due to the additional buoyancy force, and the enhanced area availability for air the ingestion. The convex-type IRS device performs better than a cylindrical-type IRS device. A nonlinear regression model based on the Levenberg-Marquardt (L-M) method has been deployed to develop a correlation equation for the air entrainment.

Molecular photothermal effects on time-resolved IR spectroscopy.

Time-resolved IR pump-probe (IR-PP) and two-dimensional IR (2D-IR) spectroscopy are valuable techniques for studying various ultrafast chemical and biological processes in solutions. The time-dependent changes of nonlinear IR signals reflecting fast molecular processes such as vibrational energy transfer and chemical exchange provide invaluable information on the rates and mechanisms of solvation dynamics and structural transitions of multispecies vibrationally interacting molecular systems. However, due to the intrinsic difficulties in distinguishing the contributions of molecule-specific processes to the time-resolved IR signals from those resulting from local heating, it becomes challenging to interpret time-resolved IR-PP and 2D-IR spectra exhibiting transient growing-in spectral components and cross-peaks unambiguously. Here, theoretical considerations of various effects of vibrational coupling, energy transfer, chemical exchange, the generation of hot ground states, molecular photothermal process, and their combinations on the line shapes and time-dependent intensities of IR-PP spectra and 2D-IR diagonal peaks and cross-peaks are presented. We anticipate that the present work will help researchers using IR pump-probe and 2D-IR techniques to distinguish local heating-induced photothermal signals from genuine nonlinear IR signals.