IR Irradiation Research Articles

Investigating the Components of Signals Produced by the Pockels CCD Imaging Technique in CdZnTe

Several groups have demonstrated the potential of the Pockels effect in cadmium zinc telluride as a means to detect ionizing radiation. Migrating charge carriers are believed to generate the signal detected via the Pockels effect due to the distortions they create within the electric field; however, trapped space charge beneath the cathode has been regularly observed, which suggests field changes away from the charge generation area. Consequently, the Pockels signal amplitude contains a charge integrated, i.e., dose element. In this paper, the effects of electric field collapse at the location of charge carrier generation are demonstrated. This opens the potential to apply the technique for imaging dose rate distributions. Charge-coupled device images representing the changes in an electric field within the crystal were taken, and the response to illumination from a collimated 1550-nm, 4.5-mW IR laser and irradiation from 150-kVp X-rays was measured. The data demonstrate that the signal acquired is a combination of both the local change in the electric field at the location where the carriers are being released/generated and an element caused by carriers becoming trapped, leading to electric field enhancement due to space charge near the cathode and field reduction toward the anode.

Anomalous Photoconduction of Low-Temperature Charge-Density Wave in NbS3-II as a Physical Basis of a Method for Detection of Weak Signals

The effect of IR radiation on photoconduction of two charge-density waves (CDWs) in the monoclinic phase of quasi-1D conductor NbS3 (NbS3-II) is studied. For the CDW-1 that emerges at a temperature of ТР1 = 360 К, threshold field Et increases with irradiation power W. For CDW-2 that emerges at a temperature of TP2 = 150 K, field Et decreases due to IR irradiation, which proves anomalous character of CDW-2 and indicates direct photoactivation of its sliding. Extremely high sensitivity of the measured signal to IR radiation is obtained using stimulation of the CDW coherence by the microwave field.

PAN filtration membranes with extended solvent stability

This work focuses on preparation of PAN membranes stable in aprotic solvents. Laboratory samples of PAN with different molecular weight were synthesized by varying the polymerization conditions. Membranes were prepared by non-solvent induced phase inversion method. Membranes prepared with higher molecular weight PAN had stable separation characteristics at pressures up to 30 bar and higher retention but lower permeability than for membranes prepared from PAN with lower molecular weight. At the same time membranes from PAN with lower molecular weight had higher but unstable in time permeabilities. The retention of Bovine serum albumin (Mw = 69 kDa) from water solutions reached the value up to 98%. After IR irradiation treatment membrane permeability for water were the same as for initial membranes and varied from 5 to 1500 kg/m2·h·bar. At the same time PAN membranes was stable toward aprotic solvents NMP, DMSO, DMFA, DMAA although initial polymer was soluble in such solvents.

Noble metal free, CeO2/LaMnO3 hybrid achieving efficient photo-thermal catalytic decomposition of volatile organic compounds under IR light

Large amounts of anthropogenic VOCs emissions give rise to photochemical smog and ground-level ozone. Currently, catalytic oxidation for VOCs elimination still requires energy-intensive high temperatures. Light-driven photo-thermocatalysis oxidation of VOCs holds great promise to substantially reduce energy consumption for sustainable development in comparison with conventional thermal-based catalytic oxidation. Herein, CeO2/LaMnO3 composite, featuring the broad light wavelength absorption (800∼1800 nm), can be used as a highly active photo-thermal responsive catalyst on VOCs decomposition under IR irradiation. The maximum photo-thermal conversion efficiency is able to reach 15.2% with a significant toluene conversion of 89% and CO2 yield of 87% under IR irradiation intensity of 280 mW/cm2, together with excellent stability of nearly 30 h. Comparative characterizations reveal that such photo-thermal catalytic activity enhancement is predominantly attributed to the synergistic effects of ultrabroadband strong light absorption, efficient light-to-heat conversion, good low temperature reducibility and high lattice oxygen mobility, originating from an intense interaction of LaMnO3 with CeO2. Toluene oxidation reaction on CeO2/LaMnO3 catalyst proceeds via a Mars-van Krevelen mechanism as evidenced by in situ diffuse reflectance infrared Fourier transform spectroscopy.

DEVELOPMENT OF MODE PARAMETERS OF IR IRRADIATION OF WEANERS ACCORDING TO ANALYSIS OF ANIMAL BEHAVIOUR USING VIDEO SURVEILLANCE SYSTEM

The research relevance is determined by the need to reduce the energy intensity of intensive livestock production. The latter is possible on the basis of innovative methods and technical means of intelligent management of complex biotechnical systems with identification of animal behaviour and control using video surveillance systems. The paper presents the results of experimental researches of the energy efficiency of an automated infrared irradiation system for weaners with irradiation modes set according to analysis of video surveillance of animal behaviour. A sign for the location of animals along the floor area relative to a warm source – a dark infrared irradiator, was defined as an ethological sign for the analysis of animal behaviour. As a result of experimental studies, based on the video surveillance data, IR-irradiation modes were determined by statistical analysis of the ethological sign of the location of animals relative to the thermal source of IR-irradiation. These modes were recorded in the program of the microcontroller, within 20 days the experimental group of animals was exposed to IR-irradiation according to the established modes. It was determined that the developed irradiation modes ensure additional profit of 2.97 roubles per animal, including economic effect for heating of 0.89 roubles per animal. The developed IR irradiation modes for weaners exclude general heating requirement. The IKOV-1 automated plant allows to develop energy-efficient zoology hygienic modes for animals management based on data processing and video surveillance equipment using air temperature sensor in the IR irradiation area. Acknowledgement. This research was supported by the Belarusian Republican Foundation for Fundamental Research under the T18M-001 Contract “Integrated energy supply for controlled biotechnical systems in agricultural production using renewable energy sources”.

A study on the measurement and prediction of LED junction temperature

In this study, an innovative method for the measurement of the LED junction temperature is proposed. In the proposed technique, the temperature values at the LED chip surface, at the solder joint, and at a substrate point in the vicinity of the LED are measured, and the results are compared with the junction temperature measured by transient thermal measurements method. The aforementioned three temperature values are precisely measured via an IR thermometry and thin wire thermocouple. For the demonstration of the feasibility of the IR thermometry to the LED chip surface, the spectral distribution of the LED emission is analyzed using a spectroradiometer. The results show that there is negligible IR irradiation at the LED, suggesting no IR-induced interference is expected for the surface temperature estimation. In order to validate the experimentally obtained temperature distribution, an FEM-based numerical study is also performed. The experimental and numerical results are shown to agree well to each other within 15%. Based on the results, an empirical equations that correlate the junction temperature and the temperature at the solder joint, substrate, and surface of LED are developed. In addition, we show that analyzation of the structure function containing thermal resistance data of LED package obtained from the transient thermal measurement can yield a good interpretation in regard to the thermal resistance of the LED itself. The proposed methodology can act as a good guideline for the thermal management of the LED-related products.

Direct determination of molecular weight distribution of calf-thymus DNAs and study of their fragmentation under ultrasonic and low-energy infrared irradiations. A charge detection mass spectrometry investigation.

Calf-thymus (CT-DNA) is widely used as a binding agent. The commercial samples are known to be "highly polymerized DNA" samples. CT-DNA is known to be fragile in particular upon ultrasonic wave irradiation. Degradation products could have dramatic consequences on its bio-sensing activity, and an accurate determination of the molecular weight distribution and stability of commercial samples is highly demanded. We investigated the sensitivity of charge detection mass spectrometry (CDMS), a single-molecule MS method, both with single-pass and ion trap CDMS ("Benner" trap) modes to the determination of the composition and stability (under multiphoton IR irradiation) of calf-thymus DNAs. We also investigated the changes in molecular weight distributions in the course of sonication by irradiating ultrasonic waves to CT-DNA. We report, for the first time, the direct molecular weight (MW) distribution of DNA sodium salt from calf-thymus revealing two populations at high (~10MDa) and low (~3MDa) molecular weights. We evidence a transition between the high-MW to the low-MW distribution, confirming that the low-MW distribution results from degradation of CT-DNA. Finally, we report also IRMPD experiments carried out on trapped single-stranded linear DNAs from calf-thymus allowing extraction of their activation energy for unimolecular dissociation. We show that single-pass CDMS is a direct, efficient and accurate MS-based approach to determine the composition of calf-thymus DNAs. Furthermore, ion trap CDMS allows us to evaluate the stability (both under multiphoton IR irradiation and in the course of sonication by irradiating ultrasonic wave) of calf-thymus DNAs.

Mild and Effective Polymerization of Dopamine on Keratin Films for Innovative Photoactivable and Biocompatible Coated Materials

AbstractMussel‐inspired polydopamine (PD) coating represents a promising route for constructing functional materials and finely tuning or completely changing their surface properties. In this work, a mild and effective method to realize the deposition of PD on keratin‐based films is reported. Reactive oxygen species (ROS), generated by keratin films doped with a photosensitizer, e.g., Azure A (AzA), upon UV–vis and vis‐near IR irradiation, are exploited to obtain the PD coating. Interestingly, the use of vis‐near IR irradiation leads to an increased production of ROS by AzA resulting in a greater PD deposition. Compared to uncoated keratin films, the PD‐keratin coated materials show a granular but homogeneous surface and an increased hydrophilicity, maintaining the ROS generation ability of AzA. This work demonstrates a useful method to effectively and rapidly functionalize with PD materials that are sensitive to temperature, pH and UV light, such as keratin. The proposed strategy allows obtaining new multifunctional biomaterials of potential interest in tissue engineering and drug delivery; in particular, the use of PD‐keratin films for near IR laser bonding of ophthalmic tissue, which is a representative case in wound healing purpose, is shown.

UV and IR Photochemistries of Malonaldehyde Trapped in Cryogenic Matrices.

UV and IR photochemistries of malonaldehyde, the simplest molecule exhibiting an intramolecular proton exchange, have been studied in four cryogenic matrices at 4.3 K, N2, Ne, Ar, and Xe. Samples have been irradiated using a UV and IR OPO type tunable laser, and with a broad band UV mercury lamp. UV and IR spectra have been recorded and compared with theoretical calculations carried out at the SAC-CI/6-31++G(d,p) (UV transitions) and B3LYP/6-311++G(2d,2p) (IR spectra) levels of theory. After deposition, the intramolecularly H-bonded form is found exclusively, while several open forms are formed upon UV irradiation. These open forms show ability to interconvert upon UV irradiation too. Some of them are also able to isomerize upon selective IR irradiations. The whole set of results allowed us to identify seven isomers among the eight postulated. The photodynamics of the electronic relaxation of malonaldehyde have also been investigated. By following the decay or rise of suited specific vibrational bands in the IR spectra, and by comparing the results with an earlier study of the homologous acetylacetone, we deduced that the electronic relaxation of malonaldehyde proceeds through singlet states, most probably through a 3-fold conical intersection, as postulated from theoretical calculations. In contrast with acetylacetone, malonaldehyde does not show fragmentation after UV excitation.

The Effective Killing Percentages of Hela Cells By Gold Nanoparticles and IR Irradiation

Cancer photothermal therapy (PTT) depends on the size, and shape of nanoparticles, consequently, on the surface plasmon resonance (SPR) peaks of the gold nanoparticles (GNPs) synthesized by pulsed laser ablation (PLA) method in Dulbecco’s Modified Eagle Medium (DMED), found to be located between (549-580) nm. The size of GNPs measured the calculation of SPR spectra, dynamic light scattering (DLS) methods and analysis of the transmission electron microscope (TEM) images were found to be ranged between (59-116) nm. The concentration of GNPs in prepared colloidal solution found ranged between (8-16) ppm. Irradiation of GNPs which incubated with Hela cells for 24 h by R light for (15,30, and 45) minutes, enhanced the killing percentage especially for GNPs diameters (50- 70) nm.

Solar‐Light‐Driven CO2 Reduction by CH4 on Silica‐Cluster‐Modified Ni Nanocrystals with a High Solar‐to‐Fuel Efficiency and Excellent Durability

AbstractCatalytic CO2 reforming of CH4 (CRM) to produce syngas (H2 and CO) provides a promising approach to reducing global CO2 emissions and the extensive utilization of natural gas resources. However, the rapid deactivation of the reported catalysts due to severe carbon deposition at high reaction temperatures and the large energy consumption of the process hinder its industrial application. Here, a method for almost completely preventing carbon deposition is reported by modifying the surface of Ni nanocrystals with silica clusters. The obtained catalyst exhibits excellent durability for CRM with almost no carbon deposition and deactivation after reaction for 700 h. Very importantly, it is found that CRM on the catalyst can be driven by focused solar light, thus providing a promising new approach to the conversion of renewable solar energy to fuel due to the highly endothermic characteristics of CRM. The reaction yields high production rates of H2 and CO (17.1 and 19.9 mmol min−1 g−1, respectively) with a very high solar‐to‐fuel efficiency (η, 12.5%). Even under focused IR irradiation with a wavelength above 830 nm, the η of the catalyst remains as high as 3.1%. The highly efficient catalytic activity arises from the efficient solar‐light‐driven thermocatalytic CRM enhanced by a novel photoactivation effect.

Semimetal bismuth mediated UV–vis-IR driven photo-thermocatalysis of Bi4O5I2 for carbon dioxide to chemical energy

Semimetal bismuth has attracted extensive interests, which were ascribed to the photo-thermal effect and co-catalyst properties. In this paper, Bi/Bi4O5I2 composites were synthesized through a molecular precursor hydrolytic process, and the sunlight induced semimetal Bi mediated photo-thermocatalysis of Bi4O5I2 for carbon dioxide to chemical energy was studied. When the optimal mole ratio of Bi: I was selected at 1.95:1, Bi/Bi4O5I2 displayed outstanding photo-thermocatalytic carbon dioxide to chemical energy (CO and CH4). Under simulate sunlight (UV–vis-IR) irradiation, the CO and CH4 generation over Bi/Bi4O5I2 enhanced to 40.02μmolh−1g−1, and 7.19μmolh−1g−1, respectively. The light to chemical energy (LTCE) conversion efficiency (80.2×10−6) was about 6.47 times than Bi4O5I2 (12.4×10−6), and 68.55 times than Bi4O5I2 without IR irradiation (1.17×10−6). The dramatically enhanced photo-thermocatalysis activity of Bi/Bi4O5I2 can be attributed to the co-catalyst and photo-thermal effect of Bi nanoparticles, which prohibiting the electron–hole recombination and accelerating light to thermal energy conversion, respectively. Furthermore, the enhanced photo-induced carrier separation rate and reaction system temperature of Bi/Bi4O5I2 was testified.

Isolation of an Antiaromatic Singlet Cyclopentadienyl Zwitterion.

The reaction of triplet tetrachlorocyclopentadienylidene with BF3 in rare gas matrices yields a zwitterion consisting of a cyclopentadienyl cation bearing a positive charge and a negatively charged BF3 unit. IR and UV-vis spectra as well as the absence of EPR signals demonstrate a singlet ground state of the zwitterion, and its calculated geometry and magnetic properties clearly reveal a strong antiaromatic character. The zwitterion is highly labile and by visible or IR irradiation rearranges via a 1,2-fluorine migration from boron to carbon. Interaction with a second molecule of BF3 stabilizes the zwitterion and suppresses the fluorine migration, thus providing a convenient and efficient synthesis of an antiaromatic molecule under very mild conditions.

IR induced photochemistry of glycolaldehyde in nitrogen matrix

The conformational equilibria and IR isomerisation processes of glycolaldehyde (HOCH2CHO) conformers have been studied at low temperature in nitrogen cryogenic matrix. The effects of selective IR irradiation, in the νOH and νCH domains, have been followed by FTIR spectroscopy. After deposition the main form is the most stable one, CC (Cis-Cis), which features an intramolecular hydrogen bond. Upon selective IR irradiation, this latter form is able to interconvert into two open forms, those called TT (Trans–Trans), and TG (Trans-Gauche). From TT and TG forms, no recovering (by tunneling, dark process, irradiation, annealing, etc.) of the initial state (i.e. CC regeneration) has been observed. However, a TT⇌TG thermal equilibrium is observed with a standard reaction enthalpy about 0.37kJmol−1.

Sensitive Photoacoustic IR Spectroscopy for the Characterization of Amino/Azido Mixed-Linker Metal-Organic Frameworks.

Photoacoustic Fourier-transform infrared spectroscopy makes it possible to determine the organic composition of mixed-linker metal-organic frameworks. The sound produced upon IR irradiation enables the discrimination of azido and amino linkers in three different MOF platforms with a sensitivity that is two orders of magnitude higher than that achieved using classic IR analysis.

Mechanically strong Janus poly(N-isopropylacrylamide)/graphene oxide hydrogels as thermo-responsive soft robots

Simple preparation of stimuli-responsive hydrogels with good mechanical properties and mild stimuliresponsiveness is essential for their applications as smart soft robots. Mechanically strong Janus poly(N-isopropylacrylamide)/graphene oxide (PNIPAM/GO) nanocomposite hydrogels with stimuli-responsive bending behaviors are prepared through a simple one-step method by using molds made of a Teflon plate and a glass plate. Residual oxygen in the air bubbles on the Teflon plate surface affects the polymerization and hence the cross-linking density, leading to the different swelling/deswelling rates of the two sides of the gels. Therefore, the hydrogels exhibit bending/unbending behaviors upon heating/cooling in water. The incorporation of GO nanosheets dramatically enhances the mechanical properties of Janus hydrogels. Meanwhile, the photo-responsive property of the GO nanosheets also imparts the hydrogels with remotecontrollable deformation under IR irradiation. The application of the Janus PNIPAM/GO hydrogels as thermo-responsive grippers is demonstrated.

Fabrication of Zinc Oxide Composite Microfibers for Near‐Infrared‐Light‐Mediated Photocatalysis

AbstractThe fabrication of photocatalysts driven by near‐infrared (NIR) light is of great scientific and technological interest to make use of solar energy. NaYF4 codoped with Yb3+ and Tm3+ upconversion nanoparticles are important nanotransducers that transfer NIR photons to high‐energy photons (UV/Vis). In this work, we demonstrated an electrospinning technique to synthesize ZnO and porous ZnO composite microfibers embedded with a large amount of NaYF4:Yb/Tm@NaYF4 nanoparticles. The morphologies, chemical compositions, and phase of the as‐prepared composites were investigated carefully by using field‐emission scanning electron microscopy, TEM, X‐ray photoelectron spectroscopy, fluorescence spectroscopy, and XRD. Steady‐state and dynamic‐state fluorescence spectra were used to demonstrate that the embedded NaYF4:Yb/Tm@NaYF4 core–shell nanoparticles can activate the ZnO nanoparticles under IR irradiation. The ZnO composite microfibers can efficiently transfer the NIR photons to the excited state of ZnO and activate the semiconductor to produce reactive oxygen species to result in the degradation of rhodamine B dyes.

The Cope Rearrangement of 1,5-Dimethylsemibullvalene-2(4)-d1 : Experimental Evidence for Heavy-Atom Tunneling.

As an experimental test of the theoretical prediction that heavy-atom tunneling is involved in the degenerate Cope rearrangement of semibullvalenes at cryogenic temperatures, monodeuterated 1,5-dimethylsemibullvalene isotopomers were prepared and investigated by IR spectroscopy using the matrix isolation technique. As predicted, the less thermodynamically stable isotopomer rearranges at cryogenic temperatures in the dark to the more stable one, while broadband IR irradiation above 2000 cm-1 results in an equilibration of the isotopomeric ratio. Since this reaction proceeds with a rate constant in the order of 10-4 s-1 despite an experimental barrier of Ea =4.8 kcal mol-1 and with only a shallow temperature dependence, the results are interpreted in terms of heavy-atom tunneling.

The Cope Rearrangement of 1,5‐Dimethylsemibullvalene‐2(4)‐d1: Experimental Evidence for Heavy‐Atom Tunneling

AbstractAs an experimental test of the theoretical prediction that heavy‐atom tunneling is involved in the degenerate Cope rearrangement of semibullvalenes at cryogenic temperatures, monodeuterated 1,5‐dimethylsemibullvalene isotopomers were prepared and investigated by IR spectroscopy using the matrix isolation technique. As predicted, the less thermodynamically stable isotopomer rearranges at cryogenic temperatures in the dark to the more stable one, while broadband IR irradiation above 2000 cm−1 results in an equilibration of the isotopomeric ratio. Since this reaction proceeds with a rate constant in the order of 10−4 s−1 despite an experimental barrier of Ea=4.8 kcal mol−1 and with only a shallow temperature dependence, the results are interpreted in terms of heavy‐atom tunneling.

Investigation of Tin(II)2,3-naphtalocyanine molecule used as near-infrared sensitive layer in organic up-conversion devices

In this work, a near infrared (NIR) sensitive molecule, Tin(II)2,3-naphthalocyanine (SnNc) was characterized by different techniques. UV–Vis spectroscopy and cyclic voltammetry were performed in order to determine the absorption spectrum, the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) energies of this molecule deposited in form of thin films. We found energies of 5.0 ± 0.1 eV and 3.7 ± 0.1 eV for HOMO and LUMO, respectively. The charge carrier mobility was also investigated by space charge limit current technique showing values of μh (8.8 ± 0.1) x 10−5 cm2V−1s−1. SnNc alone or blended with fullerene was used as efficient NIR sensitive layer due to its absorption around 875 nm. The crystalline structure of SnNc was studied by X-ray powder diffraction, showing a monoclinic system and P21/c space group, with cell parameters a = (15.948 ± 6) Å, b = (15.818 ± 2) Å, c = (14.649 ± 1) Å and β = (67.096 ± 6) Å. Desorption/Ionization-Time of Flight Mass Spectrometry (LDI-TOFMS) technique was employed to obtain information of molecular structure of the SnNc in thin film, showing that the thin film of the SnNc has no dimer formation. Due to its absorption around 875 nm, SnNc blended with fullerene was used as efficient NIR sensitive layer in the fabrication of an organic up-conversion device. When the device is submitted to IR radiation, a gain of about 133% was observed in the luminous efficiency when compared to values without IR irradiation.