IR Spectral Region Research Articles

Optical spectra and emission characteristics of terbium-doped potassium–lead double chloride crystals (KPb2Cl5:Tb3+)

Optical transitions in KPb2Cl5:Tb3+ crystals are studied experimentally and theoretically. The absorption cross-section spectra are plotted and the oscillator strengths of transitions from the ground terbium state to excited multiplets are determined. Intensity parameters Ωt for KPC:Tb3+ are determined by the Judd–Ofelt method to be Ω2 = 2.70 × 10–20 cm2, Ω4 = 7.0 × 10–20 cm2, and Ω6 = 0.72 × 10–20 cm2. These values were used to calculate such characteristics of spontaneous radiative transitions as oscillator strengths, probabilities of radiative transitions, and radiative lifetimes. The emission spectra of KPb2Cl5:Tb3+ crystals upon UV excitation and the decay kinetics of luminescence from the excited 5 D 3 and 5 D 4 levels are studied experimentally, the lifetimes of these levels are determined, and the dependences of the rates of nonradiative relaxation from the excited 7 F j (j = 0–5), 5 D 4, and 5 D 3 levels to lower-lying terbium levels are calculated. It is shown that the population of the 5 D 4 level in KPC:Tb3+ crystals occurs according to a cascade scheme, which leads to quenching of the 5 D 3 level. The calculated data agree well with the known experimental rates of multiphonon nonradiative transitions for Dy:KPC, Nd:KPC, Er:KPC, Tb:KPB, and Nd:KPB crystals. It is shown that transitions in the near-IR (3–6 μm) region in double halide crystals (MPb2Hal5) are almost unquenched and the rates of nonradiative relaxation of excited levels spaced by energy gaps ΔE ji > 1000 cm–1 are W ji NR < 103s–1. This circumstance suggests that it is possible to obtain stimulated emission in KPb2Cl5:RE3+ crystals in the IR spectral region up to 6 μm.

Design and Synthesis of BODIPY-Cored Near IR-emitting Lipophilic and Water-Soluble Dendritic Platforms

Capitalizing on our experience in constructing branched and dendritic monomers with functionalizable aromatic moiety at the focal point and various terminal groups, we prepared lipophilic and water-soluble dendrimers with BODIPY fluorophore in the core, emitting in the green and near IR spectral regions. The dendrimers, incorporating aliphatic tails, exhibited excellent fluorescence properties in apolar organic solvents, while those with the triethylenglycol-based tails were highly fluorescent in polar organic solvents as well. The water solubility induced by the terminal hexaethyleneglycol tails enables fluorescence of the dyes also in aqueous media. The phenolic hydroxyls in the molecules enable attachment of linkers for prospective conjugation of additional units.

Investigation of in vitro PDT activities of zinc phthalocyanine immobilised TiO2 nanoparticles

Phthalocyanines (Pcs) are commonly used as Photosensors (PSs) in Photodynamic Therapy (PDT) applications due to their intense absorption in the far red-near IR spectral region with a high extinction coefficient and high ability for generating singlet oxygen. Pcs targetspecifically tumors, and do not show any considerable toxic effects under the absence of light. In particular, their chemical versatility has allowed the introducion a number of substituent at the periferal or axial positions which provide modulating photophysical properties, increases the solubility of these compounds in organic solvents. Nanoparticles increase the bioavailability, stability, and transport of PSs to target tissue. TiO2 nanoparticles are prefered in these applications because of their non toxic, low cost and high chemical stability properties. In our study, a Zinc Phthalocyanine (ZnPc) was used as a photosensor. The design of ZnPc integrated TiO2 nanoparticles is intended to make PSs a more effective PDT agent. With the aim to examine the nuclear imaging/treatment potentials of ZnPc and ZnPc-TiO2 in hepatocellular carcinoma (HepG2), colorectal adenocarcinoma (HT29) tumor and human healthy lung (WI38) cell lines in vitro study ZnPc and TiO2-ZnPc were also labeled with 131I. It is determined that 131I-ZnPc-TiO2 nanoparticle show a potential as an agent for the imaging/treatment of hepatocellular cancer by in vitro. The toxicity studies revealed that TiO2 nanoparticle decreases the toxicity of ZnPc. In vitro PDT results show that TiO2-ZnPc has a potential as a PDT agent in colon tumor treatment. Consequently, synthesized ZnPc and ZnPc-TiO2 could be promising candidates as theranostic agents.

Effect of H+ implantation on the optical properties of semi-insulating GaAs crystals in the IR spectral region

The optical properties of semi-insulating GaAs crystals subjected to multienergy hydrogen-ion implantation and treatment in a high-frequency electromagnetic field are studied in the infrared spectral region. It is established that such combined treatment provides a means for substantially increasing the transmittance of GaAs crystals to values characteristic of crystals of high optical quality. On the basis of analysis of the infrared transmittance and reflectance data, Raman spectroscopy data, and atomic-force microscopy data on the surface morphology of the crystals, a physical model is proposed to interpret the effects experimentally observed in the crystals. The model takes into account the interaction of radiation defects with the initial structural defects in the crystals as well as the effect of compensation of defect centers by hydrogen during high-frequency treatment.

Linear and nonlinear behaviour of near-IR intersubband transitions of cubic GaN/AlN multi quantum well structures

The linear and nonlinear behaviour of intersubband transitions of cubic GaN/AlN multi quantum well (QW) structures in the IR spectral region is investigated. In this study photoluminescence, IR absorption as well as pump-probe measurements are done. Two cubic GaN/AlN multi quantum wells with Si content of NSi ~1019cm−3 in the cubic GaN quantum wells were grown on 3C-SiC (001) substrate by radio-frequency plasma-assisted molecular beam epitaxy. A broad IR absorption with a FWHM of 370meV was found with a maximum at 0.7eV, corresponding to the intersubband transition of the multi quantum wells. The nonlinear optical measurement reveals a clear change of transmission for a pump pulse with an angle of incidence of 65°. Furthermore, transmission electron microscopy measurements are used to determine the real layer thicknesses. These thickness values are exploited in the calculation with the Schrödinger-Poisson solver nextnano³. The simulated transition energies agree very well with the experimental data for the photoluminescence and the absorption measurement.

Photo-thermo-refractive glass with sensitivity to visible and near IR radiation

Photo-thermo-refractive glass (PTR glass) is a multicomponent silicate glass doped with Ce3+, which changes its refractive index after exposure to UV radiation followed by thermal development. It is extensively used for recording of trivial holograms (volume Bragg gratings) operating in the visible and near IR spectral regions. Ability to record complex holographic structures in PTR glass is of utmost interest as it would be advantageous for imaging and laser beam control applications. However, since photosensitivity of PTR glass is limited to the UV region, complex holograms for the visible and IR applications could not be recorded in PTR glass. To extend PTR glass sensitivity towards longer wavelengths the same glass matrix was doped with terbium, and then an excited state absorption mechanism was used for two-step excitation of the 5d14f7 band of Tb3+ ions by concurrent illumination by long wavelengths (449, 522, 808 or 975 nm) and UV (375 nm) photons. For the first time refractive index modulation exceeding 2 × 10−4 was observed after exposing the material to blue, green and near IR laser radiation. Complex holograms operating in the blue and green spectral regions were recorded in Tb-doped PTR-glass.

Growth of optically active multilayer metal oxide films on a plastic substrate

An optically active ITO/Au/ITO multilayer coating (where ITO stands for an indium tin oxide with the composition 90% In2O3 + 10% SnO2 and Au is nanoparticulate gold on a thin-film poly(ethylene terephthalate) substrate) has been prepared by a solution-phase process using an ITO nanopowder dispersion in isopropanol and a solution of chloroauric acid, which was converted to colloidal gold by photolysis. A sol–gel process has been proposed for the synthesis of tin-doped indium oxide nanopowder. The properties and composition of the powder were assessed by IR spectroscopy, thermal analysis, electron microscopy, and X-ray diffraction. The phase composition of the ITO nanopowder and the optical properties of the films grown using the nanopowder have been shown to depend on the thermal annealing conditions during synthesis. Layer-by-layer growth of metal oxide films in ITO/Au/ITO coatings influences the absorption in the composite in the IR spectral region.

Liquid optical phantoms mimicking spectral characteristics of laboratory mouse biotissues

Optical phantoms mimicking optical properties of real biotissues in the visible and IR spectral regions are developed based on measurements of the spectral characteristics of ex vivo samples of laboratory mouse biotissues. The phantoms are composed of aqueous solutions of Lipofundin, Indian ink and red ink with different spectral characteristics. The deviations of the measured absorption and scattering coefficients of phantoms in the wavelength range from the corresponding values for real biotissues do not exceed 25 % and 2 %, respectively. For phantoms in the wavelength region , the deviations of the absorption coefficient do not exceed 40 % and the deviations of the scattering coefficient do not exceed 25 %. These values, in general, fall within the range of variations for different individual mice of one strain.

Development of Free Electron Lasers in Europe Local and Global Implications – 2016

Abstract Free electron laser FELs are built in Europe mainlyB as nondependent infrastructures, or as a development of synchrotron ones. They are constructed mainly in centres which have considerable experience with synchrotron light sources of the third generation like DESY, Trieste, INFN, etc. Advances in very energetically efficient superconducting linear accelerators for electron beams, like TESLA type, caused an abrupt development of FEL machines all over Europe. New generation of FELs emits light beam of extreme intensity, good parameters, in IR, VIS, UV, EUV and X-ray spectral regions. The machine construction teams comprise also of young active researchers from Poland. In particular, these is a considerable participation of M.Sc. and Ph.D. students from Warsaw University of Technology at building of FLASH I, FLASH II, and EXFEL machines. Unique experiences gathered at work with these large experiments result in development of these young teams, and their further engagement in new initiatives: laser, laser – accelerator, inertial, plasma, plasma – energy, etc. This is what we observe with satisfaction. However, due to the lack of large research infrastructures in Poland, we are not members of the infrastructure owner clubs. Our young researchers may take part in the initiatives only indirectly as members of cooperative teams from the leading countries. As a further consequence, there is also a confined access of Polish laser and accelerator researchers to some kinds of European infrastructure development projects now under realization within the H2020.

Iron Alkynyl Helicenes: Redox-Triggered Chiroptical Tuning in the IR and Near-IR Spectral Regions and Suitable for Telecommunications Applications.

The combination of a bis-alkynyl-helicene moiety with two iron centers leads to novel electroactive species displaying unprecedented redox-triggered chiroptical switching. Upon oxidation, strong changes of vibrational modes (either local or extended coupled modes) are detected by vibrational circular dichroism and Raman optical activity. Remarkably, the sign of the optical rotation at 1.54 µm (that is, at wavelengths typically used for telecommunications) changes upon oxidation while the topology and stereochemistry of the helicene remain unchanged.

Daytime sky radiance as a source of information on surface albedo in IR spectral region. Part I

We suggest a methodical justification of determining the surface albedo in the near-infrared (NIR) region using the observations of spectral atmospheric transparency and daytime clear-sky radiance in solar almucantar. The contribution of the component describing the reflection processes to radiance at different angular distances from the Sun is analyzed. The effect of aerosol absorption on radiance components used in albedo determination is estimated. The solar zenith angle and elongation of aerosol scattering phase function are found to affect the final result of albedo calculation.

Metabolic Fingerprinting of Pseudomonas putida DOT-T1E Strains: Understanding the Influence of Divalent Cations in Adaptation Mechanisms Following Exposure to Toluene.

Pseudomonas putida strains can adapt and overcome the activity of toxic organic solvents by the employment of several resistant mechanisms including efflux pumps and modification to lipopolysaccharides (LPS) in their membranes. Divalent cations such as magnesium and calcium play a crucial role in the development of solvent tolerance in bacterial cells. Here, we have used Fourier transform infrared (FT-IR) spectroscopy directly on cells (metabolic fingerprinting) to monitor bacterial response to the absence and presence of toluene, along with the influence of divalent cations present in the growth media. Multivariate analysis of the data using principal component-discriminant function analysis (PC-DFA) showed trends in scores plots, illustrating phenotypic alterations related to the effect of Mg2+, Ca2+ and toluene on cultures. Inspection of PC-DFA loadings plots revealed that several IR spectral regions including lipids, proteins and polysaccharides contribute to the separation in PC-DFA space, thereby indicating large phenotypic response to toluene and these cations. Finally, the saturated fatty acid ratio from the FT-IR spectra showed that upon toluene exposure, the saturated fatty acid ratio was reduced, while it increased in the presence of divalent cations. This study clearly demonstrates that the combination of metabolic fingerprinting with appropriate chemometric analysis can result in practicable knowledge on the responses of important environmental bacteria to external stress from pollutants such as highly toxic organic solvents, and indicates that these changes are manifest in the bacterial cell membrane. Finally, we demonstrate that divalent cations improve solvent tolerance in P. putida DOT‑T1E strains.

Transparent ceramics prepared from ultrapure magnesium aluminate spinel nanopowders by spark plasma sintering

We have studied the properties of transparent magnesium aluminate spinel ceramics prepared by spark plasma sintering (SPS) of ultrapure nanopowders. The starting powders, of ≃ 99.98% purity, ranging in specific surface area from 30 to 160 m2/g, were prepared through the hydrolysis of alcoholic solutions of magnesium aluminum alkoxide complexes, followed by calcination at temperatures from 900 to 1100°C. SPS was carried out at 1450°C, with the holding time at the highest temperature not longer than 15 min. The transparent ceramic samples thus prepared have a transmission of up to 73% in the visible and IR spectral regions (λ = 2.5–5.0 µm). The crystallite size in the ceramics is 0.2–0.4 µm, and their microhardness is HV0.1 = 14.8–16.2 GPa.

Carbon monoxide observed in Venus’ atmosphere with SOIR/VEx

The SOIR instrument on board the ESA Venus Express mission has been operational during the complete duration of the mission, from April 2006 up to December 2014. Spectra were recorded in the IR spectral region (2.2–4.3µm) using the solar occultation geometry, giving access to a vast number of ro-vibrational lines and bands of several key species of the atmosphere of Venus. Here we present the complete set of vertical profiles of carbon monoxide (CO) densities and volume mixing ratios (vmr) obtained during the mission. These profiles are spanning the 65–150km altitude range. We discuss the variability which is observed on the short term, but also the long term trend as well as variation of CO with solar local time and latitude. Short term variations can reach one order of magnitude on less than one month periods. SOIR does not observe a marked long term trend, except perhaps at the beginning of the mission where an increase of CO density and vmr has been observed. Evening abundances are systematically higher than morning values at altitudes above 105km, but the reverse is observed at lower altitudes. Higher abundances are observed at the equator than at the poles for altitude higher than 105km, but again the reverse is seen at altitudes lower than 90km. This illustrates the complexity of the 90–100km region of the Venus’ atmosphere where different wind regimes are at play.

Some methodological aspects of oil pollution evaluation of water bodies based on the degradation of petroleum products over time

This article is focused on the analytical aspects to be addressed when evaluating an oil pollution of aqueous ecosystems associated with a complexity of oil and petroleum product content and its transformation after entering the water environment. The field of application of different determination techniques of petroleum products in water and sediments is considered based on the example of the analysis of petroleum product determination methods included in the State Registry of methods approved for the state ecological control and monitoring, and on the experimental data of Azov Sea water and sediments monitoring. Over time, the ratio of the optical properties of petroleum hydrocarbons in IR-spectral region is changing because of their qualitative and quantitative transformation, which leads to significant inconsistencies in data obtained by different methods. It is shown that hydrocarbons accumulated in samples of water and sediments are different in their content: the polycyclic aromatic hydrocarbons accumulated in sediments resist the degradation while their proportion in aqueous medium is insignificant. For an adequate evaluation of oil pollution of aqueous ecosystem the advisability to measure several optical characteristics (the absorption intensity in IR-spectral region and luminescence intensity) is shown. The opportunity to use a certain mixture as a standard solution of hydrocarbons for graduation curves in the analysis of water bodies for IR-spectral and luminescence determination methods of petroleum products is described. The proposed mixture consists of 37% hexadecane, 33% isooctane, 29.97% benzene и 0.03% fluoranthene (weight %). It has the total extinction coefficient equal to the extinction coefficient of Simard mixture, and the intensity of its luminescence occupies an intermediate position between the most disparate lightweight and heavy-weight petroleum products as well as coincides with the intensity of the bilge water which is the main source of oil pollution in water bodies. Key words: aquatic ecosystem, oil pollution, content transformation, methods description (Russian) DOI: http://dx.doi.org/10.15826/analitika.2016.20.3.006 Z .А. Temerdashev 1 , L.Ph. Pavlenko 2 , I.G.Karpokova 1 , Ya.S. Ermakova 2 , V.S. Ekilik 2 1 Kuban State University Stavropolskaya ul., 149, Krasnodar, 350040, Russian Federation 2 Azov Fisheries Research Institute Beregovaya ul., 21в, Rostov-na-Donu, 344002, Russian Federation

An Approach for Routine Analytical Detection of Beeswax Adulteration Using FTIR-ATR Spectroscopy

Abstract Although beeswax adulteration represents one of the main beeswax quality issues, there are still no internationally standardised analytical methods for routine quality control. The objective of this study was to establish an analytical procedure suitable for routine detection of beeswax adulteration using FTIR-ATR spectroscopy. For the purpose of this study, reference IR spectra of virgin beeswax, paraffin, and their mixtures containing different proportions of paraffin (5 - 95%), were obtained. Mixtures were used for the establishment of calibration curves. To determine the prediction strength of IR spectral data for the share of paraffin in mixtures, the Partial Least Squares Regression method was used. The same procedure was conducted on beeswax-beef tallow mixtures. The model was validated using comb foundation samples of an unknown chemical background which had been collected from the international market (n = 56). Selected physico-chemical parameters were determined for comparison purposes. Results revealed a strong predictive power (R2 = 0.999) of IR spectra for the paraffin and beef tallow share in beeswax. The results also revealed that the majority of the analysed samples (89%) were adulterated with paraffin; only 6 out of 56 (11%) samples were identified as virgin beeswax, 28% of the samples exhibited a higher level of paraffin adulteration (&gt;46% of paraffin), while the majority of the analysed samples (50%) were found to be adulterated with 5 - 20% of paraffin. These results indicate an urgent need for routine beeswax authenticity control. In this study, we demonstrated that the analytical approach defining the standard curves for particular adulteration levels in beeswax, based on chemometric modelling of specific IR spectral region indicative for adulteration, enables reliable determination of the adulterant proportions in beeswax.

Laser microscope-spectrum analyzer for studying intracellular accumulation of near infrared emitting photosensitizers in vitro

Measuring system based on the binocular microscope for analysis of intracellular accumulation of infrared IR photosenstizers allowing to obtain graphic data about state of analyzed objects, location of fluorescence foci and to obtain details of spectral profile of fluorescence emission centers in IR spectral region was developed. According to image of fluorescence signal distribution the location of photosensitizer accumulation in the cell may be detected accurately and the spectrum of fluorescence signal of near IR-range in the targeted point may be obtained. The developed system is quite comprehensive because there is an opportunity to choose technical parameters, operating modes, measuring methods and analysis. The advantage of the developed microscope-spectrum analyzer is an opportunity to focus emission and create high power intensity on the irradiated area by means of laser source with small-angle beam spreading, all this allow to perform ultra-precise operations with cells. Particularly, tunable size of the diaphragm opening in the far field allows to register fluorescence signal on certain cell organoids. By means of developed system the studies of accumulation of the new bacteriochlorine photosensitizers on HeLa cell line were performed. The system allowed to register accumulation of cancer cells with definite sites of selectively accumulated photosensitizer. The sites of fluorescence were the centers of accumulation of bacteriochlorine photosensitizer, this suggests that studied photosensitizer has a tendency for local accumulation in cellular organoids. The authors suggested that the developed system allowed to perform the effective and rapid screening of new photosensitizers, particularly IR bacteriochlorine photosensitizers.

Novel phenoxy-substituted subphthalocyanines possessing an extended π-system: synthesis and property investigation

Novel phenoxy-substituted subnaphthalocyanine and binuclear subphthalocyanine were synthesized. Structures of the target compounds were established by 1H NMR spectroscopy and high resolution MALDI-TOF/TOF mass spectrometry. Electronic absorption spectra of the synthesized complexes revealed the bathochromic shift of absorption maximum to the near IR spectral region as compared with subphthalocyanine.

Laser-Induced Electric Breakdown of Krypton in the UV–Near IR Spectral Region

We have experimentally studied combination breakdown (electric and optical breakdown or electro-optical breakdown) of krypton under low vacuum (p ~ 101 to 105 Pa) during simultaneous exposure to nanosecond laser pulses (λ ~ 213, 266, 355, 532, 1064 nm, τ 0.5 ~ 18 ns, I 0 ~ 109 to 1011 J/cm2) and a constant electric field (E ~ 0–13.2 kV/cm). We have demonstrated a substantial change in the ratio of the optical and electric components of the breakdown threshold I 0 (E) for different gas pressures and photon energies, as well as the presence of a synergistic effect, manifested in the many-fold decrease in the threshold values for the components of the combination treatment. The results obtained can be used to assess the breakdown processes in gas-discharge devices.

Emission intensity of the λ = 1.54 μm line in ZnO films grown by magnetron sputtering, diffusion doped with Ce, Yb, Er

The effect of the Er3+-ion excitation type on the photoluminescence spectra of crystalline ZnO(ZnO〈Ce, Yb, Er〉) films is determined in the cases of resonant (λ = 532 nm, Er3+-ion transition from 4S3/2, 2H11/2 levels to 4I15/2) and non-resonant (λ = 325 nm, in the region near the ZnO band-edge emission) excitation. It is shown that resonant excitation gives rise to lines with various emission intensities, characteristic of the Er3+-ion intracenter 4f transition with λ = 1535 nm when doping crystalline ZnO films with three rare-earth ions (REIs, Ce, Yb, Er) or with two impurities (Ce, Er) or (Er, Yb), independently of the measurement temperature (T = 83 and 300 K). The doping of crystalline ZnO films with rare-earth impurities (Ce, Yb, Er) leads to the efficient transfer of energy to REIs, a consequence of which is the intense emission of an Er3+ ion in the IR spectral region at λmax = 1535 nm. The kick-out diffusion mechanism is used upon the sequential introduction of impurities into semiconductor matrices and during the postgrowth annealing of the ZnO films under study. The crystalline ZnO films doped with Ce, Yb, Er also exhibit intense emission in the visible spectral region at room temperature, which makes them promising materials for optoelectronics.