scholarly journals ADJUSTMENT OF OPTICAL PROPERTIES AND SPECTRAL CHARACTERISTICS OF THE «IRRADIATOR – OBJECT» SYSTEM FOR TWO-STAGE IR-DRYING OF PASTA PRODUCTS

2020 ◽  
Vol 54 (2) ◽  
pp. 106-110
Author(s):  
V.M. Popov ◽  
◽  
V.A. Afonkina ◽  
E.S. Zudin ◽  
V.N. Levinsky ◽  
...  
Keyword(s):  
Optical Properties ◽  
Spectral Characteristics ◽  
Two Stage ◽  
Object System

scholarly journals Features of the two-stage formation of macroporous and mesoporous silicon structuresя

2021 ◽  
Vol 23 (1) ◽  
pp. 41-48
Author(s):  
Alexander S. Lenshin ◽  
Anatoly N. Lukin ◽  
Yaroslav A. Peshkov ◽  
Sergey V. Kannykin ◽  
Boris L. Agapov ◽  
...  
Keyword(s):  
Optical Properties ◽  
Photonic Crystal ◽  
Porous Silicon ◽  
Surface Science ◽  
Electrochemical Etching ◽  
Multilayer Structures ◽  
Macroporous Silicon ◽  
Two Stage ◽  
Mesoporous Silicon ◽  
X Ray

The aim of this work was the formation of multilayer structures of macroporous silicon and the study of their structural, morphological, and optical properties in comparison with the properties of multilayer structures of mesoporous silicon. The paper presents the results of the development of techniques for the formation of multilayer structures of porous silicon por-Si by stepwise change in the current with two-stage modes of electrochemical etching.The data on the morphology, composition, and porosity of macroporous and mesoporous silicon samples were obtained using scanning electron microscopy, IR spectroscopy, and X-ray reflectivity. It was shown that with the two-stage growth of porous silicon layers, the depth of the boundary between the layers of the structure was determined by the primary mode of electrochemical etching, while the total layer thickness increased with an increase in the current density of electrochemical etching.A comparative analysis of the relative intensity and fine structure of vibrational modes of IR spectra indicated a significantly more developed specific pore surface and greater sorption capacity of mesoporous silicon as compared to macroporous silicon.     REFERENCES 1. Pacholski C. Photonic crystal sensors based on porous silicon. Sensors. 2013;13(4): 4694–4713. https://doi.org/10.3390/s130404694 2. Harraz F. A. Porous silicon chemical sensors and biosensors: A review. Sensors and Actuators B: Chemical. 2014;202: 897–912. https://doi.org/10.1016/j.snb.2014.06.0483. Qian M., Bao X. Q., Wang L. W., Lu X., Shao J., Chen X. S. Structural tailoring of multilayer porous silicon for photonic crystal application. Journal of Crystal Growth. 2006;292(2): 347–350. https://doi.org/10.1016/j.jcrysgro.2006.04.0334. Len’shin A. S., Kashkarov V. M., Turishchev S. Yu., Smirnov M. S., Domashevskaya E. P. Effect of natural aging on photoluminescence of porous silicon. Technical Physics Letters. 2011;37(9): 789–792. https://doi.org/10.1134/S10637850110901245. Kheifets L. I., Neimark A. B. Multiphase processes in porous media. Moscow: Khimiya Publ.; 1982. 320 p. (In Russ.)6. Canham L. Handbook of porous silicon. Switzerland: Springer International Publishing; 2014. 733 p.7. Zimin S. P. Porous silicon – material with new properties. Soros Educational Journal. 2004;8(1): 101–107. Available at: http://window.edu.ru/resource/217/21217/files/0401_101.pdf (In Russ., abstract in Eng.) 8. Seredin P. V., Lenshin A. S., Goloshchapov D. L., Lukin A. N., Arsentyev I. N., Bondarev A. D., Tarasov I. S. Investigations of nanodimensional Al2O3films deposited by ion-plasma sputtering onto porous silicon. Semiconductors. 2015;49(7): 915–920. https://doi.org/10.1134/S10637826150702109. Seredin P. V., Lenshin A. S., Mizerov A. M., Leiste H., Rinke M. Structural, optical and morphological properties of hybrid heterostructures on the basis of GaN grown on compliant substrate por-Si(111). Applied Surface Science. 2019;476: 1049–1060. https://doi.org/10.1016/j.apsusc.2019.01.23910. Seredin P. V., Leiste H., Lenshin A. S., Mizerov A. M. Effect of the transition porous silicon layer on the properties of hybrid GaN/SiC/por-Si/Si(111) heterostructures. Applied Surface Science. 2020;508(145267): 1–14. https://doi.org/10.1016/j.apsusc.2020.14526711. Lenshin A. S., Barkov K. A., Skopintseva N. G., Agapov B. L., Domashevskaya E. P. Influence of electrochemical etching modes under one stage and two Stage formation of porous silicon on the degree of oxidation of its surface layer under natural conditions. Kondensirovannye sredy i mezhfaznye granitsy = Condensed Matter and Interphases. 2019;21(4): 534–543. https://doi.org/10.17308/kcmf.2019.21/2364 (In Russ., abstract in Eng.) 12. Buttard D., Dolino G., Bellet D., Baumbach T., Rieutord F. X-ray reflectivity investigation of thin p-type porous silicon layers. Solid State Communications. 1998;109(1): 1–5. https://doi.org/10.1016/S0038-1098(98)00531-613. Lenshin A. S., Seredin P. V., Agapov B. L., Minakov D. A., Kashkarov V. M. Preparation and degradation of the optical properties of nano-, meso‑,and macroporous silicon. Materials Science in Semiconductor Processing. 2015;30: 25–30. https://doi.org/10.1016/j.mssp.2014.09.04014. Ksenofontova O. I., Vasin A. V., Egorov V. V., Bobyl’ A. V., Soldatenkov F. Yu., Terukov E. I., Ulin V. P., Ulin N. V., Kiselev O. I. Porous silicon and its applications in biology and medicine. Technical Physics. 2014;59(1): 66–77. https://doi.org/10.1134/S1063784214010083

scholarly journals OPTICAL PROPERTIES OF AMORPHOUS THIN FILMS OF SODIUM-TUNGSTEN OXIDE BRONZES

2021 ◽  
pp. 430-438
Author(s):  
Борис Магометович Хуболов
Keyword(s):  
Thin Films ◽  
Optical Properties ◽  
Tungsten Oxide ◽  
Optical Density ◽  
Spectral Characteristics ◽  
Wide Band ◽  
Blue Color ◽  
Amorphous Thin Films ◽  
Near Ultraviolet ◽  
Sodium Tungsten

В работе измерены спектральные зависимости оптической плотности аморфных тонких пленок оксидной натрий-вольфрамовой бронзы тетрагональной структуры состава NaWO, конденсированной на стеклянные подложки, термостатированные при температурах 373,473 и 573 K, а так же отожженные на воздухе и в вакууме, и электрохромно окрашенных. В качестве исследуемой оптической характеристики была выбрана оптическая плотность D, пропорциональная, как известно, коэффициенту поглощения. Спектральные измерения пленок, осажденных на подложки в диапазоне температур 373,473 и 573 K показали однотипность спектральных характеристик, с пиком экситонного поглощения в ближнем ультрафиолете. Полоса минимального поглощения лежит в диапазоне длин волн 400÷460 нм, а примесного поглощения - широкой полосой в области 650 ÷1000 нм с максимумом в диапазоне 900÷1000 нм. Подобная спектральная характеристика и определяет сине-голубой цвет тонкой пленки на просвет. Изучение оптических свойств тонких пленок натрий-вольфрамовых бронз представляет собой актуальную задачу. The spectral dependences were measured of the optical density of amorphous thin films of sodium-tungsten oxide bronze of the tetragonal structure and the composition NaWO, condensed on glass substrates, thermostated at temperatures of 373, 473 and 573 K, as well as annealed in air vacuum, and electrochromically colored. The optical density D, which is proportional, as is known, to the absorption coefficient, was chosen as the studied optical characteristic. Spectral measurements of films deposited on substrates in the temperature range of 373, 473 and 573 K showed the same type of spectral characteristics, with a peak of the exciton absorption in the near ultraviolet. The band of minimum absorption lies in the wavelength range of 400÷460 nm, while that of the impurity absorption is a wide band in the region of 650÷1000 nm with a maximum in the range of 900÷1000 nm. This spectral characteristic determines the blue-blue color of a thin film in transmission. The study of the optical properties of thin films of sodium-tungsten bronzes is an urgent problem.

scholarly journals Seasonal changes in optical properties of two contrasting tropical freshwater systems

2016 ◽  
Author(s):  
Luciana P.M. Brandão ◽  
Peter A. Staehr ◽  
José F. Bezerra-Neto
Keyword(s):  
Organic Matter ◽  
Optical Properties ◽  
Dissolved Organic Matter ◽  
Spectral Characteristics ◽  
Molecular Size ◽  
Winter Period ◽  
Freshwater Systems ◽  
Chl A ◽  
Rainy Period ◽  
Tropical Freshwater

<p>We investigated how allochthonous and autochthonous sources of dissolved organic matter (DOM) affected the optical conditions and chemical characteristics of two contrasting tropical freshwater systems (Dom Helvécio-DH and Pampulha reservoir) in a dry and rainy period in 2013. We analyzed PAR (photosynthetically active radiation) and UV (ultraviolet) attenuation coefficients, nutrients, chlorophyll-a (Chl-a), dissolved organic matter (DOC) and spectral characteristics of CDOM (colored dissolved organic matter). Significant differences in CDOM sources and quantity were observed, with a dominantly terrestrial input in DH during the rainy period with approximately 50% higher DOC and Chl-a levels, and a doubling in total nitrogen (TN) and total phosphorus (TP) compared to the dry winter period. The eutrophic Pampulha had several fold higher levels of DOC, Chl-a, TN and TP, with organic matter of mostly originating from phytoplankton in both seasons. Differences in source and quantity had strong implications on water transparency, DOC concentrations, CDOM quality and its susceptibility to photo- and biodegradation. DH was several fold clearer in both the UV and PAR spectrum. In DH transparency to both UV and PAR radiation was highest during the summer, suggesting elevated photo- and biodegradation during stratification. Pampulha was most transparent in the dry period even during period of algal bloom. In both systems we observed seasonal variations in concentrations of nutrients and Chl-a, and in DH differences were also found in DOC concentrations as well as the specific UV absorbance (SUVA<sub>254</sub>) and molecular size (M). Our results documents that different sources of DOM and seasonal inputs reflect in the seasonality of apparent and inherent optical properties and nutrients availability with implications for water quality and aquatic community. </p>

Polyimide Electronic Structural and Optical Properties from First Principles Calculations

2011 ◽  
Vol 694 ◽  
pp. 597-601
Author(s):  
Jia Qi Lin ◽  
Jing Leng ◽  
Ming Hui Xia ◽  
Jun Hui Shi ◽  
Qing Guo Chi
Keyword(s):  
Optical Properties ◽  
Band Structure ◽  
Band Gap ◽  
First Principles ◽  
Energy Band ◽  
Spectral Characteristics ◽  
Energy Band Structure ◽  
First Principles Calculations ◽  
Structural And Optical Properties ◽  
The Relationship

The electronic structural and optical properties of Polyimide (PI) are studied by first principle method of density theory. It is shown that molecules orbit contribution of PI is derived from carbon 2p orbital and oxygen 2p orbital, respectively,and the band gap from the energy band structure is much smaller than that of the experimental value. It is also found that the band gap calculated from the absorption edge of absorption spectra is in agreement with the result of the energy band structure. Furthermore, the relationship between the formation of dielectric function peaks and other spectral characteristics is interpreted.

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