scholarly journals Люминесцентные свойства нестехиометрических кристаллов ниобата лития различного состава и генезиса (обзор)

2022 ◽  
Vol 130 (1) ◽  
pp. 171
Author(s):  
М.В. Смирнов ◽  
Н.В. Сидоров ◽  
М.Н. Палатников
Keyword(s):  
Wave Spectrum ◽  
Visible Region ◽  
Wavelength Region ◽  
Visible Spectrum ◽  
Luminescent Properties ◽  
Short Wave ◽  
Octahedral Cluster ◽  
Short Wavelength Region ◽  
Luminescence Centers ◽  
Near Ir

A brief review of the features of the defect structure and studies of the luminescent properties of nonlinear optical lithium niobate crystals of various compositions and genesis was given. It was established that the electron-hole pair NbNb4+-O- in the oxygen-octahedral cluster NbO6 emitted in the short-wavelength region of the visible spectrum (400-500 nm), while point defects (VLi and NbNb4+-NbLi4+ bipolarons) - in the long-wavelength region (500-620 nm). At the ratio of Li/Nb≈1 the luminescence was extinguished in the visible region of the spectrum due to decreasing the intrinsic luminescence centers. It was shown that the presence of polaron luminescence in the near-IR region (700-1050 nm) was due to the small polarons NbLi4+ and impurity ions Cr3+ localized in lithium and niobium octahedra. The energy transfer between the luminescence centers in the visible and near-IR spectral regions was detected. Moreover, luminescence in near-IR regions was dominant. Doping of LiNbO3 crystals with zinc and magnesium at ZnO<4.46 mol.% and MgO<5.29 mol.% led to decreasing luminescence of intrinsic defects (VLi, NbNb4+-NbLi4+). However, there was an increase of the contribution of the short-wave spectrum component at higher dopant concentrations because of the introduction of Zn and Mg into the origin positions of Nb ions.

scholarly journals Luminescent Properties of Composite Systems Based on Polystyrene and Erbium(III) Phthalocyaninates in Near IR Spectral Region

2018 ◽  
Vol 1 (3) ◽  
pp. e00029
Author(s):  
I.A. Belogorokhov ◽  
L.I. Belogorokhova ◽  
Yu.V. Ryabchikov ◽  
V.E. Pushkarev
Keyword(s):  
Comparative Analysis ◽  
Composite Materials ◽  
Wavelength Region ◽  
Luminescent Properties ◽  
Short Wavelength Region ◽  
Composite Systems ◽  
Near Ir ◽  
Polystyrene Matrix ◽  
First Time ◽  
Properties Of Composites

Composite materials based on polystyrene and ErIII phthalocyaninates of single-, double- and triple-decker structure were obtained, and their spectral luminescent characteristics in the near-IR (NIR) range were studied. All the ErIII complexes in these composites reveal 4f photoluminescence (PL), which is observed at 1550 nm for mono- and tris(phthalocyaninate), whereas in the case of bis(phthalocyaninate), the PL maximum is shifted to the short-wavelength region and appears at 1440 nm. A comparative analysis of the properties of composites and individual phthalocyanine compounds in films and solutions was carried out. In the case of a single-decker complex, this emission was detected for the first time in the polystyrene matrix, while for individual ErIII mono(phthalocyaninates), this process was not observed earlier.

scholarly journals Inventory of the Kirillo-Belozersky Monastery (1615): An Experience of Using Spectrosonal Visualization to Reconstruct the History of the Text

2021 ◽  
pp. 651-664
Author(s):  
Evgeny A. Lyakhovitskii ◽  
Keyword(s):  
Visible Region ◽  
Wavelength Region ◽  
Main Text ◽  
Additional Information ◽  
Near Ir ◽  
Color Differences ◽  
History Of ◽  
High Degree ◽  
First Time ◽  
Made In

The article describes the results of a codicological study of the Inventory of the Kirillo-Belozersky (St. Cyrill of Beloozero) Monastery (1615). The main codicological problem for the researchers posed by this monument is its numerous and asynchronical edits. It is possible to identify edit layers by studying the ink by means of spectrosonal imaging in near-IR wavelength region of the spectrum. This method is based on the property of inks (except those with a carbon base) to acquire transparency beyond the visible region of the spectrum (after 700 nm). As additional information, visually observed (in natural indirect daylight) color differences between inks have been used, as well as color estimation using a digital portable microscope Dinolite with Dinoscope software. As a result of the study, the main stages of work on the Inventory have been established. A significant part of the marginalia are in the same ink and handwriting as the main text: brown, with moderate transparency in near-IR wavelength region. Thus, the text was probably supplemented in the course of creation. This edit was accompanied by the text on the insert sheets made in ink that is slightly translucent in the IR region of the spectrum and has a dark brown color. The same ink was used in the main text of the manuscript. When the main text was rewritten in 1616-1617, it was compiled in a codex and significantly revised for the first time. The marker of this revision stage is light brown and yellowish-brown ink with high degree of transparency in IR wavelength region of the spectrum. In addition to the editing, the notebooks are numbered in the same light brown ink. The edit of this layer mainly included clarifications to the items description. The next significant revision of the inventory text, marked with brown ink that has low transparent in the IR wavelength region of the spectrum, refers to the period after July 22, 1621. Most of these edits, as well as the earlier ones, were devoted to clarifying descriptions, to clarifying location of objects, and to describing the monastery’s acquisitions and losses. Apparently, the later stage of editing is associated with the use of gray-brown ink, similar in spectral behavior to the ink of the main text. The record of the contribution of Prince Khvorostinin made in 1622–23 was written in this ink.

Optical Properties of Chemical Vapour Etching Based Porous Silicon for Multicrystalline Solar Cells

2017 ◽  
Vol 23 ◽  
pp. 56-62
Author(s):  
Bedra Mahmoudi ◽  
Ahmed Mouhoub ◽  
Brahim Mahmoudi ◽  
Hamid Menari ◽  
Abdennour Mougas
Keyword(s):  
Optical Properties ◽  
Porous Silicon ◽  
Chemical Vapour ◽  
Wavelength Region ◽  
Multicrystalline Silicon ◽  
Short Wavelength Region ◽  
Solar Cell Application ◽  
Hydrogen Incorporation ◽  
Near Ir ◽  
Before And After

In this paper, we report a study on the possibility of fabricating porous silicon by exposing a multicrystalline silicon surface to gaseous etchants. The structural and optical properties of porous silicon (PS) layers prepared by vapour –etching (VE) are investigated. FTIR analysis confirms the existence of hydrogen incorporation bonding to the silicon atoms. Photoluminescence measurements reveal an efficient emission around 640 nm. The optical behaviour in the 350-1000 nm wavelength range was determined before and after PS formation, resulting in a notable reduction of reflectance and an enlargement of low reflectance region into short wavelengths and near IR region after PS formation. A significant increase of the quantum efficiency particularly in the short wavelength region is observed. The results make the use of such thin film very promising for multicrystalline silicon solar cell application.

Research on ZnS Buffer Layer by RF Magnetron Sputtering for Cu(In,Ga)Se2 Solar Cells

2011 ◽  
Vol 194-196 ◽  
pp. 2259-2262
Author(s):  
Yin Qun Hua ◽  
Jie Yu ◽  
Rui Fang Chen ◽  
Cheng Chen ◽  
Rui Li Xu
Keyword(s):  
Thin Films ◽  
Optical Properties ◽  
Magnetron Sputtering ◽  
Radio Frequency ◽  
Buffer Layer ◽  
Uv Spectroscopy ◽  
Visible Region ◽  
Wavelength Region ◽  
Deposition Process ◽  
Short Wavelength Region

Nanocrystalline ZnS thin films are prepared on glass substrates under various deposition conditions (radio frequency power, and sputtering pressure) using radio frequency magnetron sputtering at room temperature. Through optimization of deposition process, very thin and uniform ZnS layer was deposited to minimize the light blocking effect in short wavelength region. This paper investigates the influence of ZnS buffer layer by magnetron sputtering,and analyses structure,surface topography,and optical properties of ZnS films by using X-ray diffraction (XRD), UV-spectroscopy measurements and scanning electronic microscope (SEM) analysis techniques. Findings show that the high-quality ZnS thin films with a good crystallinity and optical properties, which is zinc blende cubic structure with a preferred orientation, can be grown by sputtering at 300W and 0.6Pa. The films exhibit the optical transparency as high as 80% in the visible region, and the resultant ZnS thin films have a high crystallinity, low defect concentration and good optical properties with the band gap of 3.50eV.

Studies of MEH-PPV and MEH-PPV/MCMB Films and their Light Absorption in the Red Wavelength Region of the Visible Spectrum

2012 ◽  
Vol 545 ◽  
pp. 308-311
Author(s):  
Nor Diyana Abdul Aziz ◽  
Roshidah Rusdi ◽  
Norlida Kamarulzaman
Keyword(s):  
Absorption Edge ◽  
Composite Films ◽  
Visible Region ◽  
Wavelength Region ◽  
Fundamental Absorption Edge ◽  
Visible Spectrum ◽  
Electron Transition ◽  
Casting Method ◽  
Free Standing ◽  
Band Absorption

Poly [2-methoxy, 5-(2-ethyl-hexyloxy)-p-phenylene-vinylene] (MEH-PPV) is a conjugated polymer that exhibit excellent luminescence properties in the visible spectrum. The fundamental absorption edge in the film is formed by the direct allowed transitions. In this work, free-standing films of MEH-PPV and MEH-PPV/MCMB were obtained by a solvent casting method. Mesocarbon Microbead (MCMB), a type of carbon, is added to the polymer producing composite films. The films were characterized by using the UV-Vis-NIR spectrophotometer. The film samples exhibited an absorption band in the red visible region. This is due to the electron transition between the non-localized bands. However, when MCMB is doped into the polymer matrix, the band absorption edge is red-shifted compared to that of the MEH-PPV pure film. Therefore, the optical band gaps of the composite films have decreased due to the presence of MCMB.

Near Infrared Technology for Precision Environmental Measurements: Part 2. Determination of Carbon in Green Grass Tissue

2003 ◽  
Vol 11 (4) ◽  
pp. 257-267 ◽  
Author(s):  
Susumu Morimoto ◽  
W.F. McClure ◽  
Benett Crowell ◽  
Donald L. Stanfield
Keyword(s):  
Near Infrared ◽  
Wavelength Region ◽  
Visible Spectrum ◽  
Simple Fact ◽  
Short Wavelength Region ◽  
Carbon And Nitrogen ◽  
Standard Normal Variate ◽  
Average Spectrum ◽  
Standard Normal ◽  
Pls Analysis

Composting is one of the most desirable techniques for reducing waste volume. To make good compost, the correct proportions of the elements carbon and nitrogen (30: 1 ratio) are important. In this paper, carbon quantification of green grass tissue using near infrared (NIR) technology was studied. Separate studies were conducted for the short-wavelength region (SWR = 700–1100 nm, a range that includes part of the visible spectrum) and long-wavelength region (LWR = 1100–2500 nm). Several spectral pretreatments (such as SNV, derivatives etc.) were implemented to optimise the stepwise multiple linear regression (SMLR) and partial least squares (PLS) calibrations. PLS analysis was conducted for all pretreatments. Results showed that the 2nd derivative of standard normal variate (SNV) pretreatment for the LWR and the SNV pretreatment for the SWR gave the best predictions. To simplify the PLS models, a weight index (WI), was defined as the absolute value of product between the regression vector from PLS analysis and the average spectrum. A simple PLS calibration was developed using selected peak wavelengths of regression vector with a minimum WI. The simple PLS models gave better results than the full PLS calibrations. According to this analysis, the C–H stretching of the first overtone at 1860 nm and the C–H stretching of the third overtone at 874 nm were the key bands for the SWR and LWR, respectively. SMLR analysis was performed on the same spectral data used in the PLS analysis. SMLR calibrations were developed using the key band chosen in PLS analysis. Although the performance of the calibrations were not as good as the PLS calibrations, the SMLR model produced acceptable calibrations for both the SWR and LWR. The simple fact that NIR technology can be used to determine both carbon and nitrogen very quickly makes it an ideal technology for monitoring material going into a composting operation.

Near-IR Emission and upconversion luminescent properties of Tb3+/Yb3+ Co-doped HfO2/SiO2 nanoparticles

2021 ◽  
Author(s):  
Vicente Vargas ◽  
Anastasiya Sedova ◽  
Jesús Uriel Balderas ◽  
S. Carmona-Tellez ◽  
Iván Merlin ◽  
...  
Keyword(s):  
Luminescent Properties ◽  
Sio2 Nanoparticles ◽  
Near Ir ◽  
Ir Emission ◽  
Co Doped

Effects of Withdrawal Speeds on Properties of ZnO Thin Films Prepared by Sol-Gel Immerse Technique

2016 ◽  
Vol 680 ◽  
pp. 124-128 ◽  
Author(s):  
Chao Du ◽  
Yu Chun Zou ◽  
Zhi Qing Chen ◽  
Wen Kui Li ◽  
Shan Shan Luo
Keyword(s):  
Thin Films ◽  
Growth Process ◽  
Sol Gel ◽  
Wavelength Region ◽  
Zno Thin Films ◽  
Zno Films ◽  
Photoelectric Device ◽  
Near Ir ◽  
Crystal Film ◽  
Diffraction Peaks

ZnO thin films have attractive applications in photoelectric device, due to their excellent chemical, electrical and optical properties. In this paper, ZnO thin films with good c-axis preferred orientation and high transmittance are prepared on glass sheets by sol-gel immerse technique. The effects of withdrawal speeds on the growth process of thin film crystal, film crystal orientation and the crystallinity, the optical performance were investigated by XRD, SEM and UV-Vis spectrophotometry. The results show that the thin films were composed of better hexagonal wurtzite crystals with the c-axis prepared orientation. The transmittance of prepared thin films is over 80% in the visible-near IR region from 600 nm - 800 nm. ZnO films have sharp and narrow diffraction peaks, which indicates that the materials exhibit high crystallinity. With the withdrawal speeds increasing, the grain size of ZnO thin films and the intensity for all diffraction peaks were increased gradually. The growth model is changed from the stratified structure into the island structure in the growth process. The transmittance of the thin films decrease in the visible wavelength region, with the withdrawal speeds increasing.

scholarly journals Method of obtaining and studying the optical properties of carbon quantum dots.

2019 ◽  
Vol 19 (3) ◽  
pp. 226-229
Author(s):  
S.D. Bardasevska ◽  
I.M. Budzulyak ◽  
S.I. Budzulyak ◽  
B.I. Rachiy ◽  
R.V. Ilnytskyi ◽  
...  
Keyword(s):  
Raw Materials ◽  
Wavelength Region ◽  
Short Wave ◽  
Carbon Quantum Dots ◽  
Long Wavelength ◽  
Plant Raw Materials ◽  
Wave Region ◽  
Exciton Mechanism ◽  
Short Wave Region ◽  
Kinetics Of

The proposed method of synthesis of CQDs on the basis of nanoporous carbon obtained from plant raw materials. It is established that in the short-wave region a band is registered, which is due to the exciton mechanism of recombination, whereas in the long-wavelength region it is related to the state of defects. The kinetics of PL extinction is not strictly exponential, which most likely indicates the distributed nature of fading from individual emitters.

scholarly journals DIGITAL IMAGE ANALYSIS OF THE VISIBLE REGION THROUGH SIMULATION OF ROCK ART PAINTINGS

2016 ◽  
Author(s):  
Berta Carrión-Ruiz ◽  
Silvia Blanco-Pons ◽  
Jose Luis Lerma
Keyword(s):  
Rock Art ◽  
Visible Region ◽  
Visible Spectrum ◽  
Principal Component ◽  
Optical Filters ◽  
Visible Range ◽  
Redundant Data ◽  
The Difference ◽  
Entire Visible Spectrum ◽  
New Research

Non-destructive rock art recording techniques are getting special attention in the last years, opening new research lines in order to improve the level of documentation and understanding of our rich legacy. This paper applies the principal component analysis (PCA) technique in images that include wavelengths between 400-700 nm (visible  range). Our approach is focused on determining the difference provided by the image processing of the visible region through four spectral images versus an image that encompasses the entire visible spectrum. The images were taken by means of optical filters that take specific wavelengths and exclude parts of the spectrum. Simulation of rock art is prepared in laboratory. For this purpose, three different pigments were made simulating the material composition of rock art paintings. The advantages of studying the visible spectrum in separate images are analysed. In addition, PCA is applied to each of the images to reduce redundant data. Finally, PCA is applied to the image that contains the entire visible spectrum and is compared with previous results. Through the results of the four visible spectral images one can begin to draw conclusions about constituent painting materials without using decorrelation techniques.

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