Including Infrared Research Articles

Carbon-rich hexagonal (BN)C alloys

Thin films of hexagonal boron nitride carbon, h-(BN)1−x(C2)x, alloys in the C-rich side have been synthesized by metal-organic chemical vapor deposition (MOCVD) on c-plane sapphire substrates. X-ray diffraction measurements confirmed single hexagonal phase of h-(BN)1−x(C2)x epilayers. Electrical transport and Raman spectroscopy measurements results revealed evidences that homogenous h-(BN)1−x(C2)x alloys with x ≥ 95% can be synthesized by MOCVD at a growth temperature of 1300 °C. The variable temperature Hall-effect measurements suggested that a bandgap opening of about 93 meV with respect to graphite has been obtained for h-(BN)1−x(C2)x with x = 0.95, which is consistent with the expected value deduced from the alloy dependence of the energy gap of homogenous h-(BN)1−x(C2)x alloys. Atomic composition results obtained from x-ray photoelectron spectroscopy measurements revealed that the carrier type in C-rich h-(BN)1−x(C2)x alloys is controlled by the stoichiometry ratio between the B and N via changing the V/III ratio during the growth. The demonstration of bandgap opening and conductivity control in C-rich h-(BN)1−x(C2)x alloys provide feasibilities for realizing technologically significant devices including infrared (IR) emitters and detectors active from near to far IR and multi-spectral IR emitters and detectors.

Bioactivity guided fractionation and hypolipidemic property of a novel HMG-CoA reductase inhibitor from Ficus virens Ait.

BackgroundThe current perspective for the search of 3-hydroxy-3-methyl-glutaryl-coenzyme A (HMG-CoA) reductase inhibitor has been shifted towards a natural agent also having antioxidant property. Thus, this study was intended to isolate and identify the bioactive compounds from methanolic extract of Ficus virens bark (FVBM) and to evaluate their antioxidant, HMG-CoA reductase inhibitory and hypolipidemic activity.MethodsBioactivity guided fractionation and isolation of bioactive compound from FVBM extract has been done to isolate and characterize the potent HMG-CoA reductase (HMGR) inhibitor with antioxidant activity by using repeated extensive column chromatography followed by spectroscopic methods, including Infrared (IR), 1H & 13C nuclear magnetic resonance (NMR) and Mass spectrum analysis. The in vitro HMGR inhibition and enzyme kinetic assay was determined using HMG-CoA as substrate. In addition, antioxidant activity of the new isolated compound, was measured using 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay and FRAP value. In-silico molecular informatics of HMGR enzyme type inhibition and pharmacokinetics data of the new compound was further evaluated through molecular docking and ADME-T studies. Further, in-vivo hypolipidemic property of FVBM extract and newly isolated compound was also analyzed in triton-WR 1339 induced rats.ResultsThereby, we report the discovery of n-Octadecanyl-O-α-D-glucopyranosyl(6′ → 1″)-O-α-D-glucopyranoside (F18) as a novel HMG-CoA reductase inhibitor with strong antioxidant property. This inhibitor exhibited not only higher free radical scavenging activity but also marked HMG-CoA reductase inhibitory activity with an IC50 value of 84 ± 2.8 ng/ml. This inhibitory activity concurred with kinetic study that showed inhibition constant (Ki) of 84 ng/ml via an uncompetitive mode of inhibition. The inhibition was also corroborated by molecular docking analysis and in silico pharmacokinetics data. The in vivo study revealed that administration of FVBM extract (at higher dose, 100 mg/rat) and the inhibitor (1 mg/rat) to Triton WR-1339-induced hyperlipidemic rats significantly ameliorated the altered levels of plasma lipids and lipoproteins including hepatic HMG-CoA reductase activity; this effect was comparable to the effect of standard drug atorvastatin.ConclusionsThe in vitro, in silico and in vivo results clearly demonstrated the antioxidant potential and therapeutic efficacy of the inhibitor as an alternate drug against hyperlipidemia.Electronic supplementary materialThe online version of this article (doi:10.1186/s12944-015-0013-6) contains supplementary material, which is available to authorized users.

Infrared Detection Using Transparent and Flexible Field‐Effect Transistor Array with Solution Processable Nanocomposite Channel of Reduced Graphene Oxide and P(VDF‐TrFE)

Photodetectors using optically responsive graphene (Gr) or reduced graphene oxide (R‐GO) on rigid substrates have showed promising results for detection of broad band light including infrared (IR). However, there have been only a few reports on Gr or R‐GO photodetectors with new functionalities such as optical transparency and/or flexibility. Herein, a new kind of transparent and flexible IR photodetector is presented using a field‐effect transistor (FET) structure in which an IR‐responsive nanocomposite layer of R‐GO and poly(vinylidenefluoride‐co‐trifluoroethylene) (P(VDF‐TrFE)) is employed as the channel. The IR photodetector exhibits high IR responsivity, stability, and reproducibility under mechanical strain and ambient conditions. In addition, the capability of measuring the distribution of responses from each device in the transparent and flexible nanocomposite FET array under IR radiation from the human body is also demonstrated. Therefore, the development of a flexible IR photodetector with high responsivity, transparency, ease of integration, and stability in an ambient environment is a suitable alternative approach for achieving the stable monitoring of IR in many flexible and transparent electronic systems.

PARAMAGNETIC ALIGNMENT OF SMALL GRAINS: A NOVEL METHOD FOR MEASURING INTERSTELLAR MAGNETIC FIELDS

We present a novel method to measure the strength of interstellar magnetic fields based on ultraviolet (UV) polarization of starlight, which is in part produced by weakly aligned, small interstellar grains. We begin with calculating degrees of alignment of small (size $a\sim 0.01\mu$m) and very small ($a\sim 0.001\mu$m) grains in the interstellar magnetic field due to the Davis-Greenstein paramagnetic relaxation and resonance paramagnetic relaxation. We compute the degrees of paramagnetic alignment with the ambient magnetic field $B$ using Langevin equations. In this paper, we take into account various processes essential for the dynamics of small grains, including infrared (IR) emission, electric dipole emission, plasma drag and collisions with neutral and ionized species. We find that the alignment of small grains is necessary to reproduce the observed polarization in the UV, although the polarization arising from these small grains is negligible at the optical and IR wavelengths. Based on fitting theoretical models to observed extinction and polarization curves, we find that the best-fit model requires a higher degree of alignment of small grains for the case with the peak wavelength of polarization $\lambda_{\max}<0.55\mu$m, which exhibits an excess UV polarization relative to the Serkowski law, compared to the typical case $\lambda_{\max}=0.55\mu$m. We interpret the correlation between the systematic increase of the UV polarization relative to maximum polarization (i.e. of $p(6\mu m^{-1})/p_{\max}$) with $\lambda_{\max}^{-1}$ by appealing to the higher degree of alignment of small grains. We identify paramagnetic relaxation as the cause of the alignment of small grains and utilize the dependence of the degree of alignment on the magnetic field strength $B$ to suggest a new way to measure $B$ using the observable parameters $\lambda_{\max}$ and $p(6\mu m^{-1})/p_{\max}$.[Abridged]

Isolation, Identification and Molecular Docking Studies of a New Isolated Compound, from Onopordon acanthium: A Novel Angiotensin Converting Enzyme (ACE) inhibitor

Ethnopharmacological relevanceOnopordon acanthium (also known as Scotch thistle) is a medicinal plant of the Asteraceae family that is widely distributed in Europe and Asia. This plant has been long used in traditional medicine as a hypotensive, cardiotonic and diuretic agent. Aim of the studyThe present study is designed to isolate an active compound with ACE inhibition activity from O. acanthium, measure antioxidant activity, predict domain specificity and pharmacokinetic properties of the isolated compound. Materials and methodsMethanolic extract of O. acanthium seeds, has been subjected to a repeated column chromatography to give a pure compound with Angiotensin Converting Enzyme (ACE) inhibition activity. The ACE inhibition activity was determined using hippuryl-L-histidyl-L-leucine (HHL) as substrate in an in vitro ACE assay. Structure of the pure compound, isolated from O. acanthium has been established by spectroscopic methods, including Infrared (IR), Nuclear Magnetic Resonance (NMR) and Mass spectrum analysis. In addition, antioxidant activity of the new isolated compound, was measured using 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay and compared with those of BHT and Trolox as positive controls. Enzyme type inhibition and ACE-C or N domain specificity of the new compound was further evaluated through molecular modeling and docking studies. ResultsStructure of the pure compound, isolated from O. acanthium (83±1% ACE inhibition activity at concentration of 330μg/ml), has been established. The isolated compound possessed acceptable antioxidant activity (IC50 value of 2.6±0.04μg/ml) in comparison with BHT (IC50 value of 10.3±0.15μg/ml) and Trolox (IC50 value of 3.2±0.06μg/ml). Molecular docking predicted competitive type enzyme inhibition and approximately similar affinity of the isolated compound for ACE-C and N domains. ConclusionThe results derived from computational and in vitro experiments, confirm the potential of the isolated compound, from O. acanthium as a new antihypertensive compound and give additional scientific support to an anecdotal use of O. acanthium in traditional medicine to treat cardiovascular disease such as hypertension.

Comparative observation of fundus ophthalmoscopic image characteristics of central serous chorioretinopathy

Objective To observe ophthalmoscopic image characteristics of central serous chorioretinopathy (CSC).Methods Twenty-one eyes of the 18 patients diagnosed with CSC were enrolled in this study.The patients included 12 males (14 eyes) and six females (seven eyes).The patients ages ranged from 26 to 47 years,with a mean age of (39.1±5.4) years.There were nine patients (11 eyes) with acute CSC,seven patients (seven eyes) with chronic CSC,and two patients (three eyes) with recurrent CSC.All the patients were examined using color fundus photography including infrared (IR),autofluorescence (AF),near infrared ray-auto-fluorescence (NIR-AF),fluorescein angiography (FA) and indocyanine green angiography (ICGA) photography.The ophthalmoscopic image characteristics of CSC were comparared.Results The circular serous retinal detachments of 21 eyes were depicted in color images of the ocular fundus,which in the IR showed the hypo-fluorescence.Ten eyes displayed mottled hyperfluorescent spots associated with serous retinal detachments corresponding to the leakage points.The serous retinal detachments of 15 eyes in the AF images showed hypo-fluorescence,six eyes showed hyperfluorescence.Fourteen eyes presented with hypo-or hyper-fluorescent spots corresponding to the leakage points,seven eyes presented without abnormal fluorescence corresponding to the leakage points.In addition,three eyes with acute CSC showed many scattered hyper-fluorescent spots,which showed hypo-fluorescence in the ICGA.The serous retinal detachment of 15 eyes exhibited hypo-fluorescence in the NIR-AF images,six eyes showed hyper-fluorescence.Fourteen eyes presented with hypo-or hyper-fluorescent spots corresponding to the leakage points,seven eyes presented without abnormal fluorescence corresponding to the leakage points.Twenty-one eyes in FA identified the leakage.Eight eyes showed regional choroidal delayed filling,13 eyes exhibited regional choriocapillary dilatation during 1 5 minutes after injection of ICGA.During 1-5 minutes after injection of ICGA,six eyes showed more lesions than FA,three eyes showed obvious patchy hypo-fluorescence whereas the FA were normal.Conclusions CSC has its own characteristic fundus images in the IR,FA and NIR-A.FA is still the photographic method of choice,but ICGA can reveal lesions of the choroid in CSC.IR,FA and NIR-AF are not as good as FA and ICGA for detecting of leakage points. Key words: Retinal diseases/diagnosis; Choroid diseases/diagnosis; Fluorescein angiography; Indocyanine green/diagnostic use; Diagnostic imaging

Multichannel and Repeatable Self‐Healing of Mechanical Enhanced Graphene‐Thermoplastic Polyurethane Composites

A novel self-healing material, which was fabricated using few-layered graphene (FG) and thermoplastic polyurethane (TPU) via a facile method, not only exhibits a mechanical enhanced property, but also can be repeatedly healed by various methods including infrared (IR) light, electricity and electromagnetic wave with healing efficiencies higher than 98%.

A combined laboratory and modeling study of the infrared extinction and visible light scattering properties of mineral dust aerosol

Optical properties, including infrared (IR) extinction and visible light scattering of mineral dust aerosol, are measured experimentally and compared to modeling results using T‐matrix theory. The work includes studies of complex, authentic field samples of Saharan sand, Iowa loess, and Arizona road dust (ARD). Particle size distributions and aerosol optical properties are measured simultaneously. These authentic dust samples are treated as external mixtures of mineral components. The mineral compositions for the Saharan sand and Iowa loess samples have been reported by Laskina et al. [2012], and the mineralogy for ARD is derived here using a similar method. T‐matrix‐based simulations, using measured particle size distributions and a priori particle shape models, are carried out for each mineral component of the authentic samples. The simulated optical properties for the complex dust mixtures are obtained by a weighted average of the properties of the mineral components, based on a given sample mineralogy. T‐matrix simulations are then directly compared with the measured IR extinction spectra and visible light scattering phase function and linear polarization profiles for each sample. Generally good agreement between experiment and theory is obtained. Model simulations that account for differences in particle shape with mineralogy and include a broad range of eccentric spheroid shape parameters offer a significant improvement over more commonly applied models that ignore variations in particle shape with size or mineralogy and include only a moderate range of shape parameters.

Gas, Dust and Star Formation in Nearby Galaxies as Seen with the JCMT

AbstractWe combine 12CO J = 3 − 2 for 155 nearby galaxies, obtained as part of the James Clerk Maxwell Telescope (JCMT) Nearby Galaxies Legacy Survey (NGLS), with star formation rates derived from Hα luminosities to probe the relation between warm, dense gas and star formation. These data are compared with ancillary data from the literature, including infrared (IR) and 1.4 GHz radio continuum luminosities and Hi masses. We find a good correlation between CO J = 3 − 2 luminosities and Hα-derived star formation rates (SFRs), which is in agreement with previous studies. Several groups of galaxies show a peculiar behaviour in the SFR(Hα) − LCOJ = 3 − 2 plot, which disappears when using IR data. We analyse these regions and propose several hypotheses to explain this behaviour, including group interactions and very recent (≲20 Myr) bursts of star formation only traced by Hα emission. While atomic hydrogen is hardly related with SFR, molecular and total gas (Hi + H2) show similar correlations with Hα luminosities. No correlation is found between CO J = 3−2 luminosity and metallicity, although galaxies with low metallicity are more likely to not be detected. We discuss that CO J = 3 − 2 does not seem to be a significantly better tracer of the star-forming gas, but its independence from metallicity may be used to constrain the conversion factor between CO and H2.

XANES analysis of organic residues produced from the UV irradiation of astrophysical ice analogs

Organic residues formed in the laboratory from the ultraviolet (UV) photo-irradiation or ion bombardment of astrophysical ice analogs have been extensively studied for the last 15 years with a broad suite of techniques, including infrared (IR) and UV spectroscopies, as well as mass spectrometry. Analyses of these materials show that they consist of complex mixtures of organic compounds stable at room temperature, mostly soluble, that have not been fully characterized. However, the hydrolysis products of these residues have been partly identified using chromatography techniques, which indicate that they contain molecular precursors of prebiotic interest such as amino acids, nitrile-bearing compounds, and amphiphilic compounds. In this study, we present the first X-ray absorption near-edge structure (XANES) spectroscopy measurements of three organic residues made from the UV irradiation of ices having different starting compositions. XANES spectra confirm the presence of different chemical functions in these residues, and indicate that they are rich in nitrogen- and oxygen-bearing species. These data can be compared with XANES measurements of extraterrestrial materials. Finally, this study also shows how soft X rays can alter the chemical composition of samples.

Antiproliferative Lactams and Spiroenone from Adlay Bran in Human Breast Cancer Cell Lines

Two new lactams, coixspirolactam D (1) and coixspirolactam E (2), and a new spiroenone, coixspiroenone (3), together with seven known compounds, coixspirolactam A (4), coixspirolactam B (5), coixspirolactam C (6), coixlactam (7), coixol (8), ethyl dioxindole-3-acetate (9), and isoindol-1-one (10), and two neolignans, zhepiresionol (11) and ficusal (12), were isolated from the bioactive subfraction of adlay bran ethanolic extract (ABE). Compounds 9 and 10 are the first isolates from natural resources. The structures of new compounds were identified by spectroscopic methods, including infrared (IR) spectrum, 1D and 2D nuclear magnetic resonance (NMR), and mass spectrum (MS). All of the isolated compounds were tested for antiproliferative effects on MCF-7, MDA-MB-231, and T-47D cells. Results showed that compounds 1, 3, 4, 6, and 7 at 50 μM significantly inhibited MCF-7 cell proliferation by 30.2, 19.2, 21.0, 13.5, and 32.4%, respectively; compounds 2, 4, and 7 significantly inhibited T-47D cells at 50 μM by 20.7, 24.8, and 28.9%; and compounds 1, 2, and 12 significantly inhibited MDA-MB-231 cells at 50 μM by 47.4, 25.3, and 69.3%, respectively. In conclusion, ABE has antiproliferative activities, and this effect is partially related to the presence of lactams and spiroenone.

Novel biodegradable flocculating agents prepared by grafting polyacrylamide to Konjac

AbstractGrafting copolymers of polyacrylamide (PAM) with Konjac gum (KGM) have been synthesized using ceric‐ion‐induced initiation technique. The copolymers were characterized using several instrumental techniques, including infrared (IR) spectroscopy, elementary analysis, scanning electron microscopy (SEM), size exclusion chromatography (SEC) analysis, and intrinsic viscosity to confirm the success of grafting. The flocculation performance of graft copolymers was characterized by two methods. One was to study the relationship between the flocculants doses in kaolin suspension and the supernatant transmittance, and the other is to examine the time dependence of sediment height of kaolin suspensions. It was found that the graft copolymer is better than KGM and pure PAM. Biodegradation behavior was testified by monitoring the decay of relative viscosities, and approved by KGM ether bonds breaking in IR spectra and the molecule weight reduction in SEC analysis. The results indicate that the grafted KGM copolymers have improved both, flocculation performance and better biodegradable properties than the unmodified parent KGM and pure PAM. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Effect of β-Ring Rotation on the Structures and Vibrational Spectra of β-Carotene: Density Functional Theory Analysis

The effect of beta-ring rotation on the structures and vibrational spectroscopic characteristics of beta-carotene, including infrared (IR) intensities and Raman activities, is analyzed using density functional theory. Two stable isomers having Ci symmetry are obtained. The reversion of bond lengths is ascribed to the hyperconjugation effect. The natural bond orbital (NBO) charge analysis suggests that the NBO charges of C5 can be used to estimate the degree of pi-electron delocalization. These structural variations are used to analyze and assign the vibrational spectra. It is concluded that (a) the similar rotational angle dependencies of nu1 and nu2 frequencies justify the contribution of C=C stretch vibrations to the nu2 mode and explain the same conjugation length dependencies of nu1 and nu2 frequencies in polyenes, (b) the nu1 mode can be assigned to the C=C stretching in the central part of polyene chain, whereas beta-rings play an important role in nu2 and IR1 bands, especially for the all-trans isomer, and (c) the transition dipole moment of the calculated IR1 absorption band is relevant to the conjugation degree and the crossing angle between the eigenvectors of the polyene chain and the C5=C6 stretching vibration. This theoretical analysis, together with our previous Raman spectral experiments, suggests that the C6-C7 bond is easier to be twisted than other parts of beta-carotene molecule and so provides an insight into the structures of carotenoids and the properties of binding sites in carotenoproteins.

PEGDA/PVdF/F127 gel type polymer electrolyte membranes for lithium secondary batteries

A novel porous gel polymer electrolyte (GPE) membrane based on poly(ethylene glycol) diacrylate (PEGDA), poly(vinylidene fluoride) (PVdF), and polyethylene oxide-co-polypropylene oxide-co-polyethylene oxide (PEO-PPO-PEO, F127) was fabricated by a phase inversion technique. The PEGDA cross-linking oligomer could be randomly mixed with unraveled PVdF polymer chains to form the interpenetrating polymer network (IPN) structure. Several experimental techniques including infrared (IR) spectra, differential scanning calorimetry (DSC), thermogravimetric analyzer (TGA), scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS) and potentiostat/galvanostat were employed to investigate the characteristics of the polymer membranes. PEGDA and F127 influenced the porous size and structure. The mechanical strength and flexibility of the membrane were controlled by its composition. The membrane with the composition of PEGDA/PVdF/F127 (0/4/4) showed the highest electrolyte uptake of 152.6% and the maximum ionic conductivity of 2.0 × 10 −3 S cm −1 at room temperature. All GPEs prepared in this study were electrochemically stable up to 4.5 V.

Prediction among different spectroscopic properties for aqueous systems

Spectroscopic properties obtained by NMR and vibrational spectra both reflect the microscopic environment of solutions, and the local composition (LC) theory can be used to study environmental effects on spectroscopic properties. Based on the LC model, the relationship between NMR and vibrational spectra, including infrared (IR) spectroscopy and Raman, were investigated. For the aqueous systems-water+N, N-dimethylformamide, water+acetone, water+methanol, and water+ethanol, we performed prediction between concentration-dependent peak positions of IR and Raman, as well as between concentration-dependent vibrational properties and 1H NMR chemical shifts. The results showed that reliable prediction could be achieved with the help of the LC model. This suggests that 1H NMR chemical shifts and vibrational spectroscopic properties may tell us the same story about the local environment encountered in solution.

Determination of molecular line parameters for acrolein (C 3H 4O) using infrared tunable diode laser absorption spectroscopy

Acrolein (C 3H 4O) molecular line parameters, including infrared (IR) absorption positions, strengths, and nitrogen broadened half-widths, must be determined since they are not included in the high resolution transmission (HITRAN) molecular absorption database of spectral lines. These parameters are required for developing a quantitative analytical method for measuring acrolein in a single puff of cigarette smoke using tunable diode laser absorption spectroscopy (TDLAS). The task is complex since acrolein has many highly overlapping infrared absorption lines in the room temperature spectrum and the cigarette smoke matrix contains thousands of compounds. This work describes the procedure for estimating the molecular line parameters for these overlapping absorption lines in the wavenumber range (958.7–958.9 cm −1) using quantitative reference spectra taken with the infrared lead-salt TDLAS instrument at different pressures and concentrations. The nitrogen broadened half-width for acrolein is 0.0937 cm −1 atm −1 and to our knowledge, is the first time it has been reported in the literature.

Density functional and vibrational spectroscopic analysis of β‐carotene

AbstractWe report a computational study on the structural, energetic and vibrational spectroscopic characteristics of β‐carotene employing density functional theory (DFT). The optimized geometry and the complete vibrational spectrum calculated at the BPW91/6–31G* level, including infrared (IR) intensities and Raman activities, are presented. The centrosymmetric structure of β‐carotene is verified both theoretically and experimentally, by identifying a stable calculated structure with Ci symmetry and the mutually exclusive occurrence of bands in the experimental Fourier transform IR and Raman spectrum, respectively. The calculated vibrational spectra reflect the major characteristic features observed experimentally. Differences in the calculated IR intensities and Raman activities for a few dominant modes of two β‐carotene configuration isomers, the all‐trans and the natural abundant (C6–C7) s‐cis form, are explained qualitatively by the corresponding eigenvectors. At the level of theory employed, s‐cis‐β‐carotene was found to be 8.8 kJ mol−1 more stable than the all‐trans form. Calculations on β‐carotene model systems were performed to separate electronic from steric contributions. The higher stability of s‐cis‐β‐carotene is explained by an energetically favored β‐ionone ring conformation, compensating for its shorter conjugation length in comparison with the all‐trans form. Copyright © 2003 John Wiley &amp; Sons, Ltd.

Chemical depth profiling of multi-layer automotive coating systems

Detailed chemical analysis of high performance automotive coating systems can be done with a relatively available and affordable set of measurement technologies, including infrared (IR), ultraviolet–visible (UV–Vis) and optical microscopy (OM) based methods. These tools are very versatile in the ability to do both surface and interface characterization, as well as depth profiling. Their utility is illustrated using a broad range of applications: surface-specific defect analysis; stratification/segregation of network components; mechanisms/kinetics leading to coating degradation and material loss; UVA permanence in coating systems; and UVA interphase mixing between clearcoats and BCs. Many of the studies were conducted as a function of exposure time and conditions (i.e., outdoor/field environments; accelerated aging via QUV, UV only, CHC or xenon borosilicate/borosilicate protocols) or application conditions. Albeit the focus of this work is on chemistry and associated changes while in use, correlations to appearance, physical properties, and mechanical performance will be noted to underscore significance of the changes in chemical composition. Also, sampling techniques used in isolating chemical species or isolating bulk material from a given depth locus will be shown for each application. Since the approaches described herein do not require expertise/equipment that is available to only a few, these works should highlight the potential utility of such tools.

The effects of Te precipitation on IR transmittance and crystalline quality of as-grown CdZnTe crystals

The relationship of the Te precipitated phase concentration in the matrix to IR transmittance and crystalline quality of as-grown CdZnTe wafers was investigated by means of various optical and structural techniques including infrared (IR) transmission, differential scanning calorimetry (DSC) and Rutherford backscattering spectroscopy (RBS). Results indicate that Te precipitates/inclusions in CdZnTe matrix reduce IR transmittance, especially at concentration ≥0.6 wt.%. Additionally, the crystalline perfection of near-stoichiometric as-grown CdZnTe is better than that of non-stoichiometric samples, and decreases with increasing second-phase concentration.

Effect of annealing on near-stoichiometric and non-stoichiometric CdZnTe wafers

The effect of annealing on near-stoichiometric and non-stoichiometric CdZnTe crystals was investigated by means of various optical and structural techniques including infrared (IR) transmission, transmission electron microscopy (TEM), X-ray double crystal rocking curve, secondary ion mass spectroscopy (SIMS), Raman scattering (RS), and Rutherford backscattering spectroscopy (RBS). Results indicate that annealing can effectively reduce Te precipitates, especially larger ones, through thermomigration process, and purify the wafers by gettering some impurities. Additionally, annealing improves slightly the crystallinity of near-stoichiometric crystals but degrades the microstructure of non-stoichiometric wafers. The investigation implies that the annealed near-stoichiometric CdZnTe wafers are suitable as substrates for the growth of quality Hg1 − xCdxTe epitaxial films.