Search

In this study, a novel gamma-ray radiation sensor has been developed depending on a 1D photonic crystal (1D-PhC). Based on porous silicon (PSi) layer that has been penetrated by a conjugated copolymer (B-co-MP) which consists of BEHP-PPV and MEH-PPV, with a fractional ratio of 60:40. The suggested method for the development of the dosimeter is based on the shift of photonic band-gap to shorter wavelengths, where exposure to gamma-ray radiation at doses ranging from 0 to 20 kGy alters the refractive index of the (B-co-MP) copolymer. The fitted experimental data, the equation of Bruggeman effective medium, and the transfer matrix method (TMM) are the main axes in the framework of the current theoretical approach. The collected data shows that, within the visible range, the suggested sensor's sensitivity (224 nm/RIU) is high and stable over a 0-20 kGy applied-dose range. Also, we compared these results with previous research. [ABSTRACT FROM AUTHOR]

Abstract In this study, a novel gamma-ray radiation sensor has been developed depending on a 1D photonic crystal (1D-PhC). Based on porous silicon (PSi) layer that has been penetrated by a conjugated copolymer (B-co-MP) which consists of BEHP-PPV and MEH-PPV, with a fractional ratio of 60:40. The suggested method for the development of the dosimeter is based on the shift of photonic band-gap to shorter wavelengths, where exposure to gamma-ray radiation at doses ranging from 0 to 20 kGy alters the refractive index of the (B-co-MP) copolymer. The fitted experimental data, the equation of Bruggeman effective medium, and the transfer matrix method (TMM) are the main axes in the framework of the current theoretical approach. The collected data shows that, within the visible range, the suggested sensor's sensitivity (224 nm/RIU) is high and stable over a 0-20 kGy applied-dose range. Also, we compared these results with previous research.

Edamame is a nutritious and economically valuable soybean. The moisture content is an important indicator of the quality of the edamame. The traditional methods in the detection of moisture content of edamame have the disadvantage of large detection errors. In this research, the fusion of transmittance and reflectance spectra of hyperspectral imaging combined with chemometrics was proposed to predict the moisture content of edamame. Also, the effect of different preprocessing of the spectra on the predictive performance was analyzed. Single spectra, primary fusion spectra, and intermediate fusion spectra were established as the prediction models for partial least squares regression (PLSR) and partial least squares support vector regression (LSSVR), respectively. The results of the prediction models showed that the spectral transform absorption (STA) combined with PLSR has the best prediction performance for a single spectrum with predictive correlation (RP) of 0.7749 and ratio of prediction to deviation (RPD) of 1.7. Standard normal variate (SNV) combined with LSSVR has the best prediction performance for primary fusion spectra with RP of 0.8821 and RPD of 1.9. SNV combined with LSSVR has the best prediction performance for intermediate fusion spectra with RP of 0.9149 and RPD of 2.4. The Rp and RPD of prediction models of the moisture content of edamame based on fusion spectra were significantly improved compared with single spectra. Compared with primary fusion, intermediate fusion is a more suitable fusion strategy. This research provides experimental basis for the prediction of moisture content of edamame using spectral fusion combined with chemometrics. [ABSTRACT FROM AUTHOR]

The optical properties of light-absorbing materials in optical shutter devices are critical to the use of such platforms for optical applications. We demonstrate switchable optical properties of dyes and nanoparticles in liquid-based electrowetting-on-dielectric (EWOD) devices. Our work uses narrow-band-absorbing dyes and nanoparticles, which are appealing for spectral-filtering applications targeting specific wavelengths while maintaining device transparency at other wavelengths. Low-voltage actuation of boron dipyromethene (BODIPY) dyes and nanoparticles (Ag and CdSe) was demonstrated without degradation of the light-absorbing materials. Three BODIPY dyes were used, namely Abs 503 nm, 535 nm and 560 nm for dye 1 (BODIPY-core), 2 (I2BODIPY) and 3 (BODIPY-TMS), respectively. Reversible and low-voltage (≤20 V) switching of dye optical properties was observed as a function of device pixel dimensions (300 × 900, 200 × 600 and 150 × 450 µm). Low-voltage and reversible switching was also demonstrated for plasmonic and semiconductor nanoparticles, such as CdSe nanotetrapods (abs 508 nm), CdSe nanoplatelets (Abs 461 and 432 nm) and Ag nanoparticles (Abs 430 nm). Nanoparticle-based devices showed minimal hysteresis as well as faster relaxation times. The study presented can thus be extended to a variety of nanomaterials and dyes having the desired optical properties. [ABSTRACT FROM AUTHOR]

The optical properties of light-absorbing materials in optical shutter devices are critical to the use of such platforms for optical applications. We demonstrate switchable optical properties of dyes and nanoparticles in liquid-based electrowetting-on-dielectric (EWOD) devices. Our work uses narrow-band-absorbing dyes and nanoparticles, which are appealing for spectral-filtering applications targeting specific wavelengths while maintaining device transparency at other wavelengths. Low-voltage actuation of boron dipyromethene (BODIPY) dyes and nanoparticles (Ag and CdSe) was demonstrated without degradation of the light-absorbing materials. Three BODIPY dyes were used, namely Abs 503 nm, 535 nm and 560 nm for dye 1 (BODIPY-core), 2 (I2BODIPY) and 3 (BODIPY-TMS), respectively. Reversible and low-voltage (≤20 V) switching of dye optical properties was observed as a function of device pixel dimensions (300 × 900, 200 × 600 and 150 × 450 µm). Low-voltage and reversible switching was also demonstrated for plasmonic and semiconductor nanoparticles, such as CdSe nanotetrapods (abs 508 nm), CdSe nanoplatelets (Abs 461 and 432 nm) and Ag nanoparticles (Abs 430 nm). Nanoparticle-based devices showed minimal hysteresis as well as faster relaxation times. The study presented can thus be extended to a variety of nanomaterials and dyes having the desired optical properties.

In the current work, we demonstrate a design to act as a Gamma-ray radiation dosimeter based on the one-dimensional photonic crystal (1D-PhC). The basic concept of the present dosimeter is based on a Porous Silicon (PSi) infiltrated by poly-vinyl alcohol (PVA)-polymer doped with crystal violet (CV) and carbol-fuchsine (CF) dyes. The mechanism of suggested dosimeter is based on the shift of the photonic bandgap (PBG) to higher wavelengths as exposed to gamma-ray radiation doses from 0 to 70 Gray (Gy). The basic axes of the current theoretical treatment are the transfers matrix method (TMM), Bruggeman's effective medium equation, and the fitted experimental data to the refractive index of the doped PVA-Polymer. The obtained results showed the proposed sensor is characterized by high stable sensitivity varied from (178–186 nm/ RIU) along an applied γ-dose from (10–70 Gy) in the visible range. In addition, we compared these results with previous researches. In addition, based on the our knowledge may be it is the first time that a 1D-PhC has been used for gamma-ray detection by using (PVA/CV + CF) based on Porous Silicon. [ABSTRACT FROM AUTHOR]

Diabetes is becoming a global problem since it is the leading cause of mortality for many people all over the world. As a result, a diabetes sensor that is accurate, quick, and sensitive is required. On the basis of a binary photonic crystal, a new bio-photonic detector has been built for sensing diabetes-affected cells. It has two layers of Ge and TiN, with a defect cavity chosen as a sample and placed in the middle. The suggested biosensor's detecting mechanism is based on altering the refractive index of the sensing sample, which causes a shift in the location of the resonant peak inside the photonic band gap of transmittance spectra. The suggested structure's transmittance qualities are examined using the transfer matrix approach. The impact of incidence angle (TE and TM polarization) and defect cavity thickness on the performance of our proposed biosensor has been investigated. The suggested biosensor has a sensitivity of 2676.66 nm/RIU at optimal conditions, which is exceptionally high when compared to several previous studies. In addition, the suggested biosensor with a very low detection limit has an ultra-high-quality factor and figure of merit. Furthermore, the suggested detector is simple to fabricate and has a low-cost structure, making it appealing for use in a variety of bio-sensing applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • Strawberry NIR online flexible drop-free detection prototype was developed. • Transmittance spectra with effective internal quality information was acquired. • Models based on variable optimization obtained better adaptability and stability. • Technologies need to be nondestructive, low-cost, and improve farmer profits. Strawberry, as a fragile and vulnerable fruit, the realization of automatic sorting is conducive to improve the intelligent level of strawberry industry and improve the ability of product quality management. An on-line soluble solids content (SSC) detection prototype which can protect the strawberry from mechanical damage was researched and developed. The reflectance and transmittance of visible and near infrared (Vis/NIR) spectra were acquired by the prototype respectively, and the performances of the two spectra on the SSC detection performance of strawberry were compared. Four feature selection algorithms like competitive adaptive reweighted sampling (CARS) ware used for reflectance and transmittance spectra to reduce the spectra complexity, improve the strawberry SSC detection accuracy and optimize the running time of the prototype. The comparison showed that the transmittance spectra can reflect the internal SSC information of strawberry better. Then the results of feature variable selection showed that strawberry transmittance spectra combined with CARS algorithm achieved the best result of SSC prediction, and the prediction correlation coefficient (Rp) was 0.928, the root mean square error of prediction (RMSEP) was 0.412 °Brix, and the residual predictive deviation (RPD) value was 2.670. The CARS-PLS model for reflectance spectra also obtained the optimization result in the reflectance group, but its Rp, RMSEP and RPD value was 0.812, 0.587 °Brix and 1.670 respectively, which still did not meet the reliability of application. The results demonstrated that the Vis/NIR transmittance spectra have great application potential in strawberry on-line internal quality detection. [ABSTRACT FROM AUTHOR]

The superior and tunable optoelectronic properties of lead halide perovskite thin films have been used to improve the device performance of solar cells, photodetectors, and light-emitting diodes. The material properties of lead halide perovskite thin films play the important roles in determining the performance of optoelectronic devices. It is important to correctly understand the relation between the material properties and device performance in order to realize the best devices. We analyze the optical, excitonic, morphological, crystal structural, and molecular properties of lead halide perovskite thin films in order to understand the working mechanisms of the resultant optoelectronic devices and the required material properties. • The relation between material properties and optoelectronic devices is discussed. • In solar cells, γ-CsPbI 3 perovskites are predicted to result in a higher PCE. • In photodetectors, MAPbI 3 perovskites are predicted to result in a faster response time. • In light-emitting diodes, quasi-2D perovskites are predicted to result in a higher EQE. [ABSTRACT FROM AUTHOR]

In2S3, AgIn5S8, and (In2S3)x(AgIn5S8)1 –x-alloy single crystals are grown by the Bridgman method. The composition and structure of the crystals are determined. It is established that both the initial compounds and their alloys crystalize with the formation of the cubic spinel structure. The unit-cell parameters of the single crystals are calculated, and the dependences of these parameters on the alloy composition are constructed. It is shown that, in the system, Vegard's law is satisfied. The transmittance spectra of the crystals in the region of the fundamental absorption edge are studied at room temperature, and the band gap (Eg) is determined. It is shown that Eg varies with the composition parameter x, with some deviation from a linear dependence. [ABSTRACT FROM AUTHOR]

The object of our current investigation is Cu-As2Se3 thin film structures. The impact of corona discharge on photoinduced modifications of the transmission spectra of both asdeposited and exposured with actinic light of the Cu-As2Se3 structures have been studied. Two cases have been investigated. First normal irradiation of the film structures without charging, and another one, when exposure was switched on, 7 kV corona charge at different polarity was applied. As a result, in the region of the weak absorption in the transmission spectra the photobleaching effect was observed and in the region of the strong absorption the photodarkening phenomena was manifested. In the region o weak absorption higher values of photobleaching was observed during exposure in the field of positive corona discharge. The obtained results are qualitatively analyzed taking into account the photodarkening of the semiconductor during it doping with Cu ions as well as transmission increases of the structure during photodiffusion of the cupper in the amorphous semiconductor. [ABSTRACT FROM AUTHOR]

The gamma radiation induced optical properties of the tellurium dioxide films of thickness 1500 nm, deposited by thermal evaporation in the vacuum, were investigated. The dose dependences of the band gap and other optical parameters have been quantified from the transmittance spectra. The optical band gap decreases with the gamma radiation dose up to 400 Gy from 3.98 to 3.55 eV and increases beyond 400 Gy. Also, the refractive index and extinction coefficient increase appreciably with the gamma radiation dose up to 400 Gy and the two decrease beyond 400 Gy. This behavior of the optical properties is due to generation of the electronic localized states in the band gap and Urbach tail. The change in each of the optical properties due to gamma radiation can be an attractive idea for the TeO 2 film as photo-sensitive film-based dosimeter. The proposed material as dosimeter has minimum detectable effect on a dose range of 400 Gy, which is best suited for possible industrial applications such as food processing and sterilization. [ABSTRACT FROM AUTHOR]

The objective of this research was to study altered distributions of chloroplasts in cecidomyiid galls derived from the leaves of Machilus thunbergii Sieb. & Zucc. and Litsea acuminata (Blume) Kurata using confocal laser-scanning microscopy and transmittance spectra. Chloroplasts in all gall tissues gradually decreased in the direction from the exterior toward the inside larval chamber based on Integrated Optical Density (IOD) and absorptivity indices, and chloroplast distributions in various gall tissues were species-specific. Different species of herbivorous insect dramatically altered chloroplasts in their host leaves. The spectral index was significantly and positively correlated with the IOD, and therefore, the transmittance spectra could be utilized as a tool to easily and quickly study the ecophysiology of galls. [ABSTRACT FROM AUTHOR]

MnAgIn7S12 single crystals 16 mm in diameter and ~40 mm in length are grown by planar crystallization of the melt. It is shown that the material grown crystallizes with the formation of the cubic spinel structure. From the transmittance spectra recorded in the region of fundamental absorption in the temperature range 10–320 K, the band gap Eg of the single crystals and its temperature dependence are determined. The dependence has a shape typical of most semiconductor materials: as the temperature is lowered, the band gap Eg increases. A calculation is carried out, and it is shown that the calculated values are in agreement with the experimental data. [ABSTRACT FROM AUTHOR]

The annealing treatment of ZnO thin film at various temperatures was performed. The effect of this treatment on the optical properties of ZnO thin film were investigated in order to apply this film to optoelectronic devices. The optical transmittance spectra were measured and it was found that the transmittance in UV-VIS region decreased with annealing temperature . The loss of light is mainly due to the increase of carrier density, resulting from increased oxygen vacancies during the annealing process at 300°C. It was also found that the absorption edge shifted to lower energy when the film was annealed at 300°C in air.

Highlights • A three-layer structure model is adopted to consider the effect of edge in foams. • Extinction coefficients are compared between traditional and the three-layer model. • Radiative properties of nickel foam are obtained in the near infrared band. • Temperature influence on the radiative properties is analyzed in 1.3–2.2 μm. Abstract Considering the existence of edge effect caused by the cut surface of struts or sintering points will affect the actual radiative transfer process in metallic foams, a three-layer structure model is constructed to obtain their spectral radiative properties. Using the double-thickness model for reference, the real spectral radiative properties of metallic foams are calculated based on transmittance spectra. To verify the feasibility of this method, transmittance spectra of nickel foams with different cell sizes and thicknesses are measured by FTIR spectrometer system in the near infrared band. Through comparing extinction coefficients obtained by traditional single-layer structure model and the three-layer structure model proposed in this paper, it is found that extinction coefficient will be underestimated by the latter method, while the deviation can reach 13% for 20ppi nickel foam and 8% for 40ppi nickel foam. Then absorption coefficient and scattering coefficient are calculated by a prediction model with parameters corrected. Based on this method, temperature influence on extinction coefficient of nickel foam is studied from 293 K to 773 K and it is found that extinction coefficient decreases with temperature in the researched band while the maximum changing rate is 2.1% in the researched band. [ABSTRACT FROM AUTHOR]

Optical properties of oily sewage play an important role in detection of water quality index of oily sewage. The transmittance spectra of oily sewage were investigated and the optical properties of oily sewage were calculated. Transmittance spectra were measured by a TU-1900 spectrophotometer in the range of 190˜900nm in pH of 6.5˜11.8. The oily sewage optical properties were calculated by the double thickness method, and the optical properties of oily sewage with different pH were compared. The results show that the transmittance of different optical path all decreased with the increase of pH in the range of 8.7˜11.8, and the transmittance in acidic environment is much higher than that in alkaline. In the wavelength of 240˜350 nm and 650˜850 nm, the pH has obvious influence on the refractive index. With the increase of pH in range of 8.7˜11.8, the absorption index has a significant downward trend. When pH is 9.6 and wavelength range is 300˜700nm, the effect of pH change on the refractive index is greater than that of the absorption index.When the solution is neutral, the fitting of the optical properties of oily sewage is the best. [ABSTRACT FROM AUTHOR]

The refractive index of the infrared thin films was calculated by a relatively simple and accurate spectroscopy method. Using the Sellmeier dispersion model, the refractive index and thickness of the Zinc sulfide(ZnS) thin film were obtained by fitting the transmittance in the range of 2.5 μm–11 μm. At the same time, the refractive index and thickness of the ZnS thin films were also measured by VASE ellipsometer. The results show that the refractive index deviation between the values fitted by the transmittance and that measured by the VASE ellipsometer is<0.02, and the relative deviation of the thickness is <1%.The YbF 3 /ZnS bilayer coatings were deposited on the CVD Zinc selenide(ZnSe) substrate to obtain the refractive index of the ytterbium fluoride(YbF 3 ) thin films wrapped in the coatings. Using the Sellmeier dispersion model, the refractive index of the YbF 3 thin film wrapped in the coatings was obtained by fitting the transmittance of the YbF 3 /ZnS bilayer coatings in the range of 2.5 μm–11 μm. The results show that there are significant differences in the refractive index of the YbF 3 thin films wrapped in coatings and that exposed to the atmosphere.The refractive index of the YbF 3 thin film exposed to the atmosphere is abrupt because the YbF 3 thin films adsorbs water vapor, while that of the YbF 3 thin film wrapped in the coatings is no mutation. [ABSTRACT FROM AUTHOR]

The optical properties of oilfield wastewater play an important role in the study of oilfield wastewater. Optical constants are the important parameters of optical properties, which are usually obtained by measuring transmittance spectra. Transmittance spectra of oilfield wastewater in the wavelength range of 190–900 nm at normal incidence were measured by a TU-1900 double beam ultraviolet visible spectrophotometer. The optical constants of oilfield wastewater were calculated by the double thickness method. The results show that the optical constants of oilfield wastewater with different oil content are different. The refractive index of oilfield wastewater increases with oil content increasing, and the values of them are in the range of 1.06–1.17. The absorption index of oilfield wastewater increases with the increase of oil content, and the values of them are in the range of 2.70 × 10 −7 - 7.60 × 10 −7 . [ABSTRACT FROM AUTHOR]

Optical properties of oilfield wastewater play an important role in the on-line measurement of oil content. As an important parameter of optical properties, absorption coefficient is usually obtained by indirectly modeling transmittance spectra. In this work, transmittance spectra of oilfield wastewater in the wavelength range of 190–900 nm at normal incidence were measured by TU-1900 double beam ultraviolet visible spectrophotometer. The absorption coefficient of oilfield wastewater was obtained by a double thickness method, and the relationship between the oil content in oilfield wastewater and its absorption coefficient was studied. The results show that the transmittance spectra of oilfield wastewater decrease with the increase of oil content. The oil content of oilfield wastewater is found to correlate negatively with its transmittance. The oil content of oilfield wastewater and its absorption coefficient have a good fitting effect at 234 nm, and the fitting error of three order polynomial fitting is minimal, with a range of 0.02–5.39%, and the fitting accuracy is 0.9940. [ABSTRACT FROM AUTHOR]

Ytterbium fluoride (YbF3) single thin films were prepared on sapphire and monocrystalline silicon substrates through conventional thermal evaporation and ion beam-assisted deposition (IAD), at bias voltages ranging from 50 to 160 V of the Leybold advanced plasma source (APS). By using the Cauchy dispersion model, the refractive index and thickness of the YbF3 thin films were obtained by fitting the 400-2500 nm transmittance of the monolayer YbF3 thin films on the sapphire substrate. At the same time, the refractive index and thickness of the YbF3 thin films on the monocrystalline silicon substrates were also measured using the VASE ellipsometer at wavelength from 400 to 2200 nm. The results showed that the refractive index deviation of the YbF3 thin films between the fitted values by the transmittance spectra and the measured values by the VASE ellipsometer was <0.02 and the relative deviation of the thickness was <1%. Furthermore, the refractive index of the YbF3 thin films increased with increasing APS bias voltage. The conventional YbF3 thin films and the IAD thin films deposited at low bias voltage revealed a negative inhomogeneity, and a higher bias voltage is beneficial for improving the homogeneity of YbF3 thin films. [ABSTRACT FROM AUTHOR]

Abstract: The laccase‐catalyzed oxidative polymerization of monomeric and dimeric lignin model compounds was carried out with oxygen as the oxidant in aqueous medium. The oligomers were characterized by using gel permeation chromatography (GPC) and matrix‐assisted laser desorption ionization time‐of‐flight mass spectroscopy (MALDI‐TOF MS) analysis. Oxidative polymerization led to the formation of oligomeric species with a number‐average molecular weight (Mn) that ranged from 700 to 2300 Da with a low polydispersity index. Spectroscopic analysis provided insight into the possible modes of linkages present in the oligomers, and the oligomerization is likely to proceed through the formation of C−C linkages between phenolic aromatic rings. The oligomers were found to show good UV light absorption characteristics with high molar extinction coefficient (5000–38 000  m−1 cm−1) in the UV spectral region. The oligomers were blended independently with polyvinyl chloride (PVC) by using solution blending to evaluate the compatibility and UV protection ability of the oligomers. The UV/Vis transmittance spectra of the oligomer‐embedded PVC films indicated that these lignin‐like oligomers possessed a notable ability to block UV light. In particular, oligomers obtained from vanillyl alcohol and the dimeric lignin model were found to show good photostability in accelerated UV weathering experiments. The UV‐blocking characteristics and photostability were finally compared with the commercial low‐molecular‐weight UV stabilizer 2,4‐dihydroxybenzophenone. [ABSTRACT FROM AUTHOR]

Ytterbium fluoride (YbF3) single thin films were prepared on sapphire and monocrystalline silicon substrates through conventional thermal evaporation and ion beam-assisted deposition (IAD), at bias voltages ranging from 50 to 160 V of the Leybold advanced plasma source (APS). By using the Cauchy dispersion model, the refractive index and thickness of the YbF3 thin films were obtained by fitting the 400–2500 nm transmittance of the monolayer YbF3 thin films on the sapphire substrate. At the same time, the refractive index and thickness of the YbF3 thin films on the monocrystalline silicon substrates were also measured using the VASE ellipsometer at wavelength from 400 to 2200 nm. The results showed that the refractive index deviation of the YbF3 thin films between the fitted values by the transmittance spectra and the measured values by the VASE ellipsometer was <0.02 and the relative deviation of the thickness was <1%. Furthermore, the refractive index of the YbF3 thin films increased with increasing APS bias voltage. The conventional YbF3 thin films and the IAD thin films deposited at low bias voltage revealed a negative inhomogeneity, and a higher bias voltage is beneficial for improving the homogeneity of YbF3 thin films. [ABSTRACT FROM AUTHOR]

Amorphous indium tin oxide (ITO) thin films were deposited on polymethylmethacrylate and polyethyleneterephthalate substrates by radio frequency magnetron sputtering at room temperature. An interesting substrate morphology effect of ITO films on the conductivity, optical transition type and energy band structure was observed. A simplified film system model with a square potential for surface morphology was employed to explain the difference of conductivity. The energy band structures were also calculated based on the theory of amorphous semiconductor. The conclusion demonstrated the width of optical band gap, as well as the relative position of the Fermi level and mobility edge, which can easily be extended to the band structure determination of other transparent conductive films. [ABSTRACT FROM AUTHOR]

Polyacrylamide (PAM) is a macromolecular polymer, and its solution is widely applied in oil exploitation, sewage treatment and paper making. Transmittance spectrum of PAM solution in the infrared wavelength region at normal incidence was investigated by an IRTracer-100 spectrometer, and the optical constants of PAM solution were obtained based on modelling transmittances combined with Kramers-Kronig ( K - K ) dispersion equation. The results show that the transmittance of PAM solution is higher than that of distilled water due to polyacrylamide. The transmission spectra shapes of PAM solution with different concentrations are similar in the wavelength range of 400–4000 cm −1 , and it contains two strong absorption bands and two obvious peaks. The absorption index and refractive index of PAM solution all increased first and then decreased with the increase of concentration in the wavelength range of 2400–2800 cm −1 . The absorption index and refractive index of PAM solution in the concentration range of 20–800 mg/L are 3.42 × 10 −3 –9.13 × 10 −3 and 1.22–1.43, respectively. [ABSTRACT FROM AUTHOR]

Transmittance spe ctrum of ZnSe in the infrared and visible wavelength range at normal incidence was investigated by an IRTracer-100 spectrometer and a TU-19 Double-Beam Visible spectrophotometer, and the optical constants of ZnSe were obtained based on modelling transmittances of two ZnSe slabs. The results show that the transmittance values of the ZnSe slabs are higher than 0.7 in the wavelength range of 2.5-15 μm; however they decrease dramatically when the wavelength is larger than 15 μm. The refractive index of ZnSe varies within 2.6-2.8 in the wavelength range of 0.55-0.85 μm and 2.2-2.4 in the wavelength range of 2.5-20 μm. The extinction coeffi cient of ZnSe varies within 10-10 in the wavelength range of 0.55-0.85 μm and 10-10 in the wavelength range of 2.5-20 μm. [ABSTRACT FROM AUTHOR]

An improved double-thickness method combined with genetic algorithm was developed to determine the optical constants of liquid hydrocarbon fuels. Different from traditional transmission measurement, it obtained the total transmittance of a window-liquid-window three-layer structure, which is the ratio of the transmission intensity of the filled cell and that of the empty sample compartment. Also, the change of the surface reflectance at the interface of the liquid sample and the optical window and the difference between forward reflection and back reflection are considered. Experiments were operated to measure spectra in the wavelength range of 0.83-2.2 mm using a Fourier transform infrared (FT-IR) spectrometer. To verify the reliability of this method, optical constants of the distilled water were determined from its experimental transmittance spectra and the results agreed well with published data. On the basis of verification, the transmittance spectra of Chinese No. -35 diesel fuel were measured at 300 K, 350 K, and 400 K with liquid sample thicknesses of 0.5mm and 1.0 mm. Then the optical constants of the diesel sample were obtained and the temperature dependence was analyzed. Analytical results indicate that the biggest change of the extinction coefficient between 300 K and 400 K can reach 30%, while that of the refractive index is 4.7%. [ABSTRACT FROM AUTHOR]

Samarium chloride coordinated urea-thiourea semi-organic complex was prepared at room temperature by slow evaporation technique. The complexes were prepared with high degree of crystallinity. The unit cell parameters determined by powder X-ray diffraction reveals the complex to be having orthorhombic system with Pnmaspace group. The dielectric measurements were made by impedance spectroscopy and various dielectric parameters were studied as a function of temperature and frequency. The ac conductivity is governed by Arrhenius type behaviour and universal power law. In optical analysis, the transmittance characteristics of complexes were studied in ultra-violet and visible region of electromagnetic spectrum. [ABSTRACT FROM AUTHOR]

The feasibility of visible and near infrared (VIS/NIR) transmittance spectroscopy for nondestructive discrimination of healthy and diseased onion bulbs was examined. Rottenness occurring in inner scales that were hard to diagnose by the five human senses was targeted. First, VIS/NIR spectra were acquired for six bulb positions. Subsequently, the degree of rot was measured by visual inspection of vertically cut surface based on our proposed criteria and by weighing of sectioned rotted parts. Our evaluation criteria functioned as an alternative mode of the weighing method. The basal plate of onion bulb had remarkable scattering properties. Therefore, spectral features differed not only by the rot levels but also by positioning the bulb against the sensor setup. The partial least squares regression model developed from the longitudinal position, for which the basal plate did not overlap against the system optical axis, showed the best performance and classified rotted bulbs above level 1 with 98.4% accuracy. Absorbance below 736 nm was the informative region for bulb rottenness detection. [ABSTRACT FROM AUTHOR]

Copyright of Przegląd Elektrotechniczny is the property of Przeglad Elektrotechniczny and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)