Journal articles: 'Kubelka Munk equation'

1

Loyalka, S. K., and C. A. Riggs. "Inverse Problem in Diffuse Reflectance Spectroscopy: Accuracy of the Kubelka-Munk Equations." Applied Spectroscopy 49, no. 8 (August 1995): 1107–10. http://dx.doi.org/10.1366/0003702953964976.

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In diffuse reflectance spectroscopy the Kubelka-Munk equations have been used extensively. These equations provide simple solutions to the inverse problem of obtaining information on the scattering and absorption cross sections from reflected light. Proof is provided that the basic Kubelka-Munk equation [Formula: see text] should be replaced by the equation [Formula: see text] and that the Kubelka-Munk function [Formula: see text] should be replaced by the function [Formula: see text] Here r( x) is the reflectance; s is the scattering cross section (cm−1); a = ( k + s)/ s, where k is the absorption cross section (cm−1); and R∞ is the reflection coefficient of an infinitely thick sample. We note, however, that because of a redefinition of a carried out by Kubelka and Munk in the process of their calculations, the scattering cross section s calculated from their expression [Formula: see text] is correct. But the Kubelka-Munk theory still overestimates k by a factor of two.

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Law, Donald P., Anthony B. Blakeney, and Russell Tkachuk. "The Kubelka–Munk Equation: Some Practical Considerations." Journal of Near Infrared Spectroscopy 4, no. 1 (January 1996): 189–93. http://dx.doi.org/10.1255/jnirs.89.

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Notwithstanding that the Kubelka–Munk function [F( R)] is the theoretically preffered treatment, relative to log 1/ r, for reflectance data, it has found little favour with workers in near infrared (NIR) reflectance. The most often quoted advantage for F( R) is an improvement in linearity with concentration, which occurs when measurements are made over a wide range of reflection and concentration. However, the practice in NIR is to limit the reflectance range by standardising the method of sample preparation. Hence, the linearity of log 1/ r is not an issue. However, is this restriction on sample preparation methodology a result of the use of log 1/ r? This study shows that moisture changes in ground wheat fractions are linear with F( R) and curvilinear with log 1/ r, and demonstrates that a calibration for moisture in wheat based on F( R) and a large reflectance range, can be successfully transferred to an instrument substantially different from that used to develop the calibration.

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Dahm, Donald J. "Why Does the Kubelka—Munk Equation “Fail”?" NIR news 14, no. 2 (April 2003): 17–18. http://dx.doi.org/10.1255/nirn.709.

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Landi, Salmon. "Comment on “Kubelka-Munk function” – Ceram. Int. 47 (2021) 8218–8227 and “Kubelka-Munk equation” – Ceram. Int. 47 (2021) 13980–13993." Ceramics International 47, no. 19 (October 2021): 28055. http://dx.doi.org/10.1016/j.ceramint.2021.06.103.

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KOZLOV, I. O. "REVIEW OF APPROACHES TO DESCRIPTION OF LIGHT SCATTERING IN BIOLOGICAL TISSUE." Fundamental and Applied Problems of Engineering and Technology 3 (2020): 131–39. http://dx.doi.org/10.33979/2073-7408-2020-341-3-131-139.

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The article discusses various approaches to modeling the processes of light scattering in biological tissues. The analytical radiation transfer equation, the Tversky approach, the Bethe–Salpeter equation, and the ladder approximation are considered. For cases of single scattering, the Kubelka–Munk approach, the diffusion approximation, and the small perturbation method are presented. The mathematical principles of the considered methods are disclosed in the paper and the limits of applicability in solving the radiation transfer equation are analyzed.

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Christy, Alfred A., Olav M. Kvalheim, and Rance A. Velapoldi. "Quantitative analysis in diffuse reflectance spectrometry: A modified Kubelka-Munk equation." Vibrational Spectroscopy 9, no. 1 (May 1995): 19–27. http://dx.doi.org/10.1016/0924-2031(94)00065-o.

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Mandelis, Andreas, and J. P. Grossman. "Perturbation Theoretical Approach to the Generalized Kubelka-Munk Problem in Nonhomogeneous Optical Media." Applied Spectroscopy 46, no. 5 (May 1992): 737–45. http://dx.doi.org/10.1366/0003702924124754.

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The generalized Kubelka-Munk problem is considered in nonhomogeneous optical media with arbitrary depth-dependent absorption and scattering coefficients. Regular perturbation theory is applied to the resulting Riccati equation, and explicit expressions are derived for the diffuse reflectance and transmittance of a finite thickness layer. The first-order perturbation solution to the problem with exponentially distributed absorption and scattering coefficients is presented, and the implications for the quantitative study of nonhomogeneous optical media, such as powdered layers, are discussed.

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LOVE, R. B., S. OGLESBY, and I. GAILEY. "The Relation between Dye Concentration and Reflectance-Amendments to the Kubelka-Munk Equation." Journal of the Society of Dyers and Colourists 81, no. 12 (October 22, 2008): 609–14. http://dx.doi.org/10.1111/j.1478-4408.1965.tb02637.x.

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Li, Jiao, Jiao Shi, Yuanbiao Li, Zhanlai Ding, and Jianguo Huang. "Response to letter to the editor re: Comment on “Kubelka-Munk function” – Ceram. Int. 47 (2021) 8218–8227 and “Kubelka-Munk equation” – Ceram. Int. 47 (2021) 13980–13993." Ceramics International 47, no. 19 (October 2021): 28056. http://dx.doi.org/10.1016/j.ceramint.2021.06.102.

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Amirshahi, S. H., and M. T. Pailthorpe. "Applying the Kubelka-Munk Equation to Explain the Color of Blends Prepared from Precolored Fibers." Textile Research Journal 64, no. 6 (June 1994): 357–64. http://dx.doi.org/10.1177/004051759406400608.

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Osawa, Masahiko. "The measurement of meat pigments by fibre-optic reflectance spectrophotometry using the Kubelka-Munk equation." Meat Science 40, no. 1 (January 1995): 63–77. http://dx.doi.org/10.1016/0309-1740(94)00019-4.

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GONG, ROLAND, PAUL D. FLEMING, JOHN CAMERON, and JAN PEKAROVIC. "Deinking evaluation using near infrared narrow band digital image analysis." AUGUST 2016 15, no. 8 (September 1, 2016): 533–38. http://dx.doi.org/10.32964/tj15.8.533.

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The current deinking evaluation methods include visual image analysis (manual and digital) and optical reflectance (using the Kubelka-Munk equation). The mechanism of image analysis is simple: dark ink (mostly black) is isolated from the light background (fiber) and then captured visually or by digital devices. The image analysis methods have inherent limits, such as poor correlation with paper optical properties, and have large variances from sample to sample and side to side. In this paper, an innovative approach that employs a band of near infrared light and a digital imaging device was applied to address these limitations. This approach has advantages for isolating specks from backgrounds, obtaining high quality raw data, and significantly reducing the variances among the handsheets and their sides. By using the ink elimination equation derived from image analysis, reliable ink elimination rates were obtained that were well correlated with paper optical properties. This system was also applied to newspaper deinking evaluation with positive results.

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Miljkovic, Milena, Milovan Purenovic, Mile Novakovic, and Sonja Randjelovic. "Influence of the fluorescent brightener Periblanc BA on the degree of whiteness of the knitted cotton fabric." Chemical Industry 65, no. 1 (2011): 61–66. http://dx.doi.org/10.2298/hemind100810061m.

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In this study the influence of the different fluorescent brightener Periblanc BA concentrations on the degree of knitted cotton fabric whiteness was investigated. Two consecutive experimental runs were performed. The first was the bleaching of the knitted cotton fabric with hydrogen peroxide using the methods of two and single bath exhaustion while the second was the optical bleaching with fluorescent brightener Periblanc BA using the exhaustion method. CIE Whiteness Index and Tint value were measured on the Color-Eye 3000 spectrophotometer at the standard illuminant D65 (Ice-Texicon, d/8, D65/10?) while K/S values were determined using the Kubelka Munk equation. The results show that cotton fabric bleached with fluorescent brightener Periblanc BA after bleaching with hydrogen peroxide using two bath exhaustion method has higher degree of whiteness (118.8) with a reddish tint in comparison to the one bleached with hydrogen peroxide using single bath method (106.1).

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Burger, T., J. Kuhn, R. Caps, and J. Fricke. "Quantitative Determination of the Scattering and Absorption Coefficients from Diffuse Reflectance and Transmittance Measurements: Application to Pharmaceutical Powders." Applied Spectroscopy 51, no. 3 (March 1997): 309–17. http://dx.doi.org/10.1366/0003702971940404.

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A measurement and data evaluation technique for the separate determination of the scattering and absorption properties of loose pharmaceutical powders is described. The equation of radiative transfer for diffuse reflectance and transmittance is analytically solved by using a three-flux approximation. Combined transmittance and reflectance measurements then allow one to derive both the scattering and the absorption coefficients. The scattering and absorption coefficients provide more information about particle size, degree of agglomeration, and chemical composition of the samples in comparison to the usual determination of only the ratio of the coefficients from diffuse reflectance measurements on optically thick samples. Furthermore, the theory of diffuse reflectance of optically thick samples according to Kubelka and Munk is compared to the three-flux approximation. The influence of the particle size on the scattering and absorption coefficient is investigated, and it is shown that the assumption of a wavelength-independent scattering coefficient, though often made in reflectance spectroscopy, is not generally valid.

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Prabhakaran, G., and Ramaswamy Murugan. "Synthesis of Cu₂O Nanospheres and Cubes: Their Structural, Optical and Magnetic Properties." Advanced Materials Research 938 (June 2014): 114–17. http://dx.doi.org/10.4028/www.scientific.net/amr.938.114.

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In this work, synthesis strategy of Cu2O nanosphere and cube was elucidated and the structural, optical and magnetic properties were studied. Cu2O nanospheres and cubes were synthesized by wet chemical method through selecting the appropriate amount of isopropyl alcohol (IPA) with distilled water as solvent. 5% of IPA yielded cubic shape Cu2O and 30% of IPA yielded spherical Cu2O. The phase purity was confirmed with powder XRD. The FTIR result exhibit Cu (I)-O vibrational band around 628 cm-1 supports the XRD results. In Raman spectra weak band at 508 cm-1 corresponds to Raman allowed mode. The IR active bands at 110 and 150 cm-1 are observed because of the violation of selection rules which demonstrates the defects present in synthesized Cu2O. Raman peaks at 218 and 415 cm-1 are assigned to multiphonon Raman scattering. The UV-Vis diffuse reflectance spectrum was recorded to calculate the band gap value. The band gap value calculated using Kubelka-Munk equation was 2.015 eV and 2.025 eV, respectively, for Cu2O cube and nanosphere.

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Hampel, Boglárka, Lucian Baia, Klara Hernadi, and Zsolt Pap. "The Influence of the Ratio of Au and Pt Nanoparticles in Ternary Composites with TiO2." Metals 11, no. 4 (April 13, 2021): 628. http://dx.doi.org/10.3390/met11040628.

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In the present work, ternary composites were synthesized from commercial titanias (Evonik Aeroxide P25, Aldrich anatase—AA and Aldrich rutile—AR) and two noble metals (gold and platinum). This research focuses on the composition of the photocatalysts, especially on the noble metals. The ratio between the noble metals varies from 0.25 to 0.75% in each composite for each noble metal. Transmission electron microscopy (TEM), X-ray diffraction (XRD) and diffuse reflectance spectroscopy (DRS) measurements were carried out to investigate the structural and optical properties. From the TEM, it can be observed that the particle sizes of the noble metals were between 1 and 4 nm, while the (anatase and rutile) crystals of P25 were 20–40 nm. The XRD showed that the semiconductors’ composition remained unchanged during/after the deposition of noble metal nanoparticles. By the DRS measurements, using the Kubelka–Munk equation, it can be concluded that the deposition of the noble metal nanoparticles resulted the decrease of the bandgap energies of the titanias. The photocatalytic activity was investigated under the irradiation of UV light. Oxalic acid and salicylic acid were used as model pollutants. The hydrogen production capacity was investigated as well, where the sacrificial agent was oxalic acid, and UV irradiation was used.

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Chen, Hsiu-Yu, Shang-Lien Lo, and Hsiang-Ling Chang. "Microwave-Assisted Synthesis of Titanate Nanotubes Loaded with Platinum with Enhanced Selectivity for Photocatalytic H2 Evolution from Methanol." Nano 15, no. 10 (September 30, 2020): 2050129. http://dx.doi.org/10.1142/s1793292020501295.

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Titanate nanotubes (TNTs) fabricated through microwave-assisted synthesis were examined for their ability to catalyze hydrogen production from a 20% v/v methanol solution under UV and visible light irradiation. Herein, TiO2 was used not only as the raw material for TNT synthesis but also as a reference support to compare its performance with that of TNTs. The UV–Vis spectral analyses of the TNT composites showed greater shifts toward the visible region after Pt loading than the spectra of Pt/TiO2. Moreover, using the Kubelka–Munk equation and Tauc Plot method, we determined that the direct allowed transition in TNT composites was more probable than the indirect allowed transition. The photocatalytic performances were evaluated by measuring the hydrogen production, and the experimental results showed that Pt/TNTs exhibited higher activity than Pt/TiO2. Furthermore, bare TNTs and Pt/TNTs showed lower CO generation than bare TiO2 and Pt/TiO2. As such, TNT composites enhanced the photocatalytic selectivity for H2 generation from formic acid to a greater extent than Pt/TiO2, because the kinetic diameter of CO (0.38[Formula: see text]nm) is larger than that of CO2 (0.33[Formula: see text]nm). This result may be attributed to the inability of CO to diffuse into the pores of TNTs because of the diameter difference. Also, XPS results showed negative shifts of Pt binding energies and positive shifts of Ti binding energies due to the strong metal-support interaction between Pt and TNTs. Thus, the remarkably high photocatalytic efficiency of TNT composites facilitates their application as promising photocatalysts.

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Setyani, Atik, Sri Wahyuni, Sigit Priatmoko, Emas Agus Prastyo Wibowo, and Nur Amin. "Synthesis and Characterization of TNTs/Polyaniline Composite as Photocatalyst Degradation of Rhodamin B by Visible Light." KnE Life Sciences 3, no. 5 (September 11, 2017): 41. http://dx.doi.org/10.18502/kls.v3i5.977.

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The purpose of this research is to study the effect of the amount of aniline on their photocatalytic activity. Nano TiO2 was synthesized using sol-gel method with TiPP precursor. XRD characterization results showed that nano TiO2 with calcination temperature of 450 °C had size of 13.8 nm with high crystalline. The diffraction peaks of nano TiO2 at 2θ are 24.45°; 37.075°; 47.26° and 53.18°. Nano TiO2 was then synthesized with hydrothermal treatment 24 h of 140 °C to produce TNTs. The results of XRD analysis shows anatase phase with field (004) and (200). The morphology of TNTs begins to form at the calcinations temperature of 600 °C with textural coefficient value of 0.998 3 . Synthesis of composite TNTs/PANI (polyaniline) was done by in situ polymerization technique of aniline which was already contained nano TiO2. The molar ratio of aniline and APS in the synthesis of a composite is 1:1.5 with the addition of aniline of 15 %; 20 % and 25 % (w/w %). Characterization using FTIR showed the stretching vibration of the C=N in wavelength of 1 600 cm–1 to mark the formation of quinonoid compounds of polyaniline. The test of the rhodamine B degradation gave the best results on the 25 % TNTs/PANI composite, with the degradation percentage of 58.73 %. The characterization results using dr-uv proved that the decrease of energy gap in the TNTs/PANI composite which as evidenced with Kubelka-Munk calculation equation that was 25 % TNTs/PANI amounting to 3.19 eV and TNTs at 3.24 eV.

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Al-Hada, Naif Mohammed, Rafiziana Md. Kasmani, Hairoladenan Kasim, Abbas M. Al-Ghaili, Muneer Aziz Saleh, Essam M. Banoqitah, Abdulsalam M. Alhawsawi, et al. "The Effect of Precursor Concentration on the Particle Size, Crystal Size, and Optical Energy Gap of CexSn1−xO2 Nanofabrication." Nanomaterials 11, no. 8 (August 22, 2021): 2143. http://dx.doi.org/10.3390/nano11082143.

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In the present work, a thermal treatment technique is applied for the synthesis of CexSn1−xO2 nanoparticles. Using this method has developed understanding of how lower and higher precursor values affect the morphology, structure, and optical properties of CexSn1−xO2 nanoparticles. CexSn1−xO2 nanoparticle synthesis involves a reaction between cerium and tin sources, namely, cerium nitrate hexahydrate and tin (II) chloride dihydrate, respectively, and the capping agent, polyvinylpyrrolidone (PVP). The findings indicate that lower x values yield smaller particle size with a higher energy band gap, while higher x values yield a larger particle size with a smaller energy band gap. Thus, products with lower x values may be suitable for antibacterial activity applications as smaller particles can diffuse through the cell wall faster, while products with higher x values may be suitable for solar cell energy applications as more electrons can be generated at larger particle sizes. The synthesized samples were profiled via a number of methods, such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FT-IR). As revealed by the XRD pattern analysis, the CexSn1−xO2 nanoparticles formed after calcination reflect the cubic fluorite structure and cassiterite-type tetragonal structure of CexSn1−xO2 nanoparticles. Meanwhile, using FT-IR analysis, Ce-O and Sn-O were confirmed as the primary bonds of ready CexSn1−xO2 nanoparticle samples, whilst TEM analysis highlighted that the average particle size was in the range 6−21 nm as the precursor concentration (Ce(NO3)3·6H2O) increased from 0.00 to 1.00. Moreover, the diffuse UV-visible reflectance spectra used to determine the optical band gap based on the Kubelka–Munk equation showed that an increase in x value has caused a decrease in the energy band gap and vice versa.

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Chen, J. "Kubelka-Munk equations in vector–matrix forms and the solution for bidirectional vegetative canopy reflectance." Applied Optics 24, no. 3 (February 1, 1985): 376. http://dx.doi.org/10.1364/ao.24.000376.

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Birdeanu, Mihaela, Mirela Vaida, and Eugenia Fagadar-Cosma. "The Optical Properties of Crystalline Zn3Nb2O8Nanomaterials Obtained by Hydrothermal Method." Journal of Chemistry 2015 (2015): 1–5. http://dx.doi.org/10.1155/2015/752089.

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The present study is focused on the obtaining of the Zn3Nb2O8nanomaterial using the hydrothermal method and its characterization through different techniques. X-ray diffraction at room temperature revealed that a novel crystalline form of the nanomaterial forms at 1100°C belonging to monoclinic space group C2/c. Field-emission scanning electron microscopy evidenced the columnar morphology of the particle’s agglomeration and the high resolution electron transmission microscopy confirms the measured interplanar distances calculated from the X-ray diffraction experiments. Using the UV-VIS spectrum and Kubelka-Munk equations, the absorbance and the band gap for the Zn3Nb2O8nanomaterial were calculated. PL spectrum reveals a single peak at 465 nm corresponding to the blue color fluorescence. The novel crystalline nanomaterial might find applications in fluorescence covering of technical devices, due to its capacity to preserve blue fluorescence both in acrylic based paint and after embedding in isopropyl alcohol.

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Tsuchikawa, Satoru. "Non-Traditional Applications of near Infrared Spectroscopy Based on the Optical Characteristic Models for a Biological Material Having Cellular Structure." Journal of Near Infrared Spectroscopy 6, no. 1 (January 1998): 41–46. http://dx.doi.org/10.1255/jnirs.119.

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Non-destructive measurements, based on near infrared (NIR) spectroscopy, on biological material with a cellular structure like wood require a non-traditional approach. We have developed new concepts to model the optical properties of a sample having cellular structure, for the illumination conditions of the spectrometer available to us. A set of optical models, which consisted of the directional characteristics models, the light-path models and the equivalent surface roughness model was proposed to clarify the behaviour of light propagation in a wood sample. Furthermore, the mean optical path length, which was derived by incorporating the nth power cosine model of radiant intensity into the diffusion process model in consideration of the parallel beam component of incident light, was calculated. By introducing the concept of equivalent sample thickness, compatible with the mean optical path length, into the Kubelka–Munk theory, generalised input/output equations for radiation were constructed. In this non-traditional application of NIR spectroscopy, these optical concepts make it possible to analyse both the physical condition and chemical composition of a biological material with a cellular structure.

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Haddadi, Ataollah, Guillaume Hans, Brigitte Leblon, Zarin Pirouz, Satoru Tsuchikawa, Joseph Nader, and Kevin Groves. "Determination of Optical Parameters and Moisture Content of Wood with Visible–Near Infrared Spectroscopy." Journal of Near Infrared Spectroscopy 24, no. 6 (January 1, 2016): 571–85. http://dx.doi.org/10.1255/jnirs.1174.

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We used the Kubelka-Munk theory equations for calculating the absorption coefficient (Kλ), the scattering coefficient ( Sλ), the transport absorption (σλa), the reduced scattering coefficient [σλs(1 – g)] and the penetration depth (δλ) from visible-near infrared reflectance spectra acquired over thin samples of quaking aspen and black spruce conditioned at three different moisture levels. The computed absorption and scattering coefficients varied from 0.1 mm−1 to 4.0 mm−1 and from 5.5 mm−1 to 10.0 mm−1, respectively. The absorption coefficients varied according to the absorption band, but the scattering coefficients decreased slowly towards high wavelengths. The sample moisture content was then estimated using the partial least squares (PLS) regression method from the Kλ and/or Sλ spectra, and the resulting PLS models were compared to those obtained with raw and transformed [multiplicative scatter corrected (MSC), first and second derivative] absorption spectra. The best PLS models for black spruce, quaking aspen and both species were obtained when only the 800–1800 nm range was used with the raw or MSC spectra. They led to a root mean square error of cross validation ( RMSECV) of 1.40%, 1.09% and 1.23%, respectively, and to a coefficient of determination ( R2CV) higher than 0.94. We also found that the Kλ spectra between 800 nm and 1800 nm can provide PLS models having an acceptable accuracy for moisture content estimation ( R2CV = 0.83 and RMSECV = 2.32%), regardless of the species.

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Urdapilleta-Inchaurregui, Vianey, Fabián Fernández-Luqueño, Aidé Minerva Torres-Huerta, Daniela Roa-Velázquez, Francisco Javier Rodríguez-Varela, and María Esther Sánchez-Castro. "Nanocomposite Synthesis from a Natural Clay-Rich Soils and Exhausted Coffee Grounds for Environmental Applications." Journal of Nano Research 63 (June 2020): 47–63. http://dx.doi.org/10.4028/www.scientific.net/jnanor.63.47.

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Natural clays, engineered Ag-nanoparticles (NP), TiO2-NP, and exhausted coffee grounds were used to synthesize a nanocomposite 7NC using a Vertisol soil through a single-step by thermal method, to build a nanomaterial to degrade or filtrate pollutants from soils, water or air. The surface characteristics and the porosity of the composite were studied through nitrogen gas adsorption at liquid nitrogen temperature and application of the Brunauer–Emmett–Teller (BET) equation and the results indicated that the microporous composites ranged a surface area of 17.36 m2 g-1. X-ray diffraction showed crystalline structure and crystalline phase of the nanocomposites. HR-TEM-STEM results demonstrated that TiO2-NP surrounded Ag-NP, and both were impregnated on natural soil nanoparticles. Oxidation states of the Ag-NP and TiO2-NP were analyzed by X-ray photoelectron spectroscopy (XPS) The energy gap of nanocomposite 7NC was determined using the Kubelka-Munck model from Ultraviolet–visible diffuse reflectance (UV–Visible DRS) spectra. The photocatalytic activity of these nanocomposites was evaluated, and the results indicated that nanocomposite with Vertisol-soil-NP (7NC) degraded the harmful organic compound methylene blue (MB) while the antimicrobial activity and resistance against Escherichia coli and Staphylococcus aureus and the zone of inhibition (ZOI) also were analyzed. The nanocomposites Ag-NP/TiO2-NP/natural-soil-NP/exhausted coffee-ground showed its for the development of an efficient material for environmental remediation with photocatalytic and antimicrobial activity.

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Wang, Wen-Yi, Jia-Chi Chiou, Wan-Xue Chen, Jia-Li Yu, and Chi-Wai Kan. "Biosafety evaluation and quantitative determination of poly(hexamethylene biguanide) (PHMB) coated on cellulosic fabrics by Kubelka–Munk equation." Cellulose, May 18, 2021. http://dx.doi.org/10.1007/s10570-021-03939-y.

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Baray-Calderón, Alejandro, R. Galindo, J. L. Maldonado., Omar Martínez-Alvarez, L. S. Acosta-Torres, José Santos-Cruz, J. de la Fuente-Hernández, and M. C. Arenas-Arrocena. "Colloidal copper sulfide nanocrystals: Electrochemical, electrical and morphological properties." MRS Proceedings 1748 (2015). http://dx.doi.org/10.1557/opl.2015.441.

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ABSTRACTThe highlight of this work is the synthesis of copper sulfide nanocrystals by a simple one-pot colloidal process, and the study of its electrochemical, electrical and morphological properties. Nanocrystals of Cu1.8S of about 15-30 nm were obtained at a temperature of 240°C under an argon atmosphere. The colloidal solution of the nanocrystals was analyzed by cyclic voltammetry. Agreeing to the values of EOx and ERedvs. SCE, and the average of three samples the HOMO and LUMO levels are 6.16 and 4.27 eV, respectively, the calculated HOMO – LUMO (Eg) is 1.89 eV. The Eg value, differs of that value obtained from Kubelka-Munk equation (1.7 eV). The photocurrent vs. time results showed that the Cu1.8S/Cu junction is photosensitive and could be used as absorbing material. The morphology and the topography of the film were analyzed by SEM and AFM techniques. Irregular agglomeration of nanocrystals was observed and a roughness of about 194 nm.

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Fazlali, F., and S. Gorji Kandi. "Identification of pigments in artworks by inverse tangent derivative of spectrum and a new filtering method." Heritage Science 8, no. 1 (September 24, 2020). http://dx.doi.org/10.1186/s40494-020-00438-4.

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Abstract Employing an economical and non-destructive method for identifying pigments utilized in artworks is a significant aspect for preserving their antiquity value. One of the non-destructive methods for this purpose is spectrophotometry, which is based on the selected absorption of light. Mathematical descriptive methods such as derivatives of the reflectance spectrum, the Kubelka–Munk function and logarithm have been employed for the characterization of the peak features corresponding to the spectrophotometric data. In the present study, the mentioned mathematical descriptive methods were investigated with the aim to characterize the constituents of an Iranian artwork but were not efficient for the samples. Therefore, inverse tangent derivative equation was developed on spectral data for the first time, providing considerable details in the profile of reflectance curves. In the next part, to have a simpler and more practical method it was suggested to use filters made up of pure pigments. By using these filters and placing them on the samples, imaging was done. Then, images of samples with and without filter were evaluated and pure pigments were distinguished. The mentioned methods were also used to identify pigments in a modern Iranian painting specimen. The results confirmed these methods with reliable answers indicating that physical methods (alongside chemical methods) can also be effective in determining the types of pigments.

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Moghazy, Marwa A., and Gharib H. Taha. "Leidenfrost Method for Synthesis of BiFeO3 and the Effect of Solvent Variation on Its Optical Properties and Morphology." Current Nanomaterials 05 (September 10, 2020). http://dx.doi.org/10.2174/2468187310999200910093034.

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Background: Nanotechnology has wide application in various fields of life. To synthesis nanoparticles many different methods have been used. Although these methods form nanoparticles with different morphologies and properties, it needs expensive tools, multi-steps, various chemicals and yields toxic by- products. The trend today to use green synthesis with one step self- assembly methods and eco-friendly one. Objective: In this manuscript, high pure BiFeO3 (BFO) multiferroic perovskite was prepared using the green chemical Leidenfrost technique as a cost-effective and eco-friendly method. Methods: Two different solvents (viz, water and ethylene glycol) were used for the synthesis of BiFeO3 nanoparticles. The resulting nanopowder was characterized by XRD, SEM, FTIR and U-Visible spectrometric techniques. Results: The XRD results show that BiFeO3 was developed in a pure phase in the case of water solvent, whereas one peak of a Bi2O3 phase was observed in case of ethylene glycol solvent. The crystallite size was determined using the Scherrer equation to be 36.58 and 61.02nm for aqueous and non-aqueous solvents, respectively (viz, water and ethylene glycol). The optical band gap was determined using Kubelka-Munk function which appears a blue shift from 2.08 eV for ethylene glycol to 1.80 eV for aqueous solvent. Conclusion: Leidenfrost method prove its efficiency for synthesis BFO nanoparticles with low cost and simple steps. The high dependence of the purity and optical properties on the solvent variation was perceived.

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Haney, Matthew M., and Kasper van Wijk. "Modified Kubelka-Munk equations for localized waves inside a layered medium." Physical Review E 75, no. 3 (March 1, 2007). http://dx.doi.org/10.1103/physreve.75.036601.

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Journal articles on the topic 'Kubelka Munk equation'

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