scholarly journals Nano Gold Spheres and Rods: Synthesis and Characterization

2021 ◽  
Vol 2114 (1) ◽  
pp. 012032
Author(s):  
Saif M. Ali ◽  
Logean Qadri Al-Karam
Keyword(s):  
Near Infrared ◽  
Visible Range ◽  
Infrared Range ◽  
Nano Gold ◽  
Atomic Force ◽  
Transmission Electron ◽  
Three Samples ◽  
Uv Visible ◽  
Shape Sphere ◽  
Two Peaks

Abstract The present study aims to synthesised nano gold with chemical method with two shape sphere and rod with multi diameter and aspect ratio and then characterize the synthesised material with Atomic Force Microscope (AFM), Transmission Electron Microscope (TEM) and Ultraviolet-visible (UV–Visible ) spectrophotometer. The AFM and TEM characterization result of three samples for each sphere and rods show that the synthesised material are in nano range with diameter 31.9 nm, 36.19 nm and 79.37 nm respectively for nano sphere and diameters 39.9nm, 36.05 nm and 28 nm respectively for nano-rods samples and the UV-Visible spectrophotometer show that peak of surface plasmon resonance of nano-sphere are at wavelengths 532 nm, 535 nm and 546 nm and all are in the visible range and nano-rod have two peaks one in the visible range at wavelengths 525nm,518nm and 531nm and the other peak is in the near infrared range at wavelengths 633nm, 680nm and 875 nm respectively.

scholarly journals Citrus Lemon Juice Mediated Preparation of AgNPs/Chitosan-Based Bionanocomposites and Its Antimicrobial and Antioxidant Activity

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
S. Rajeshkumar
Keyword(s):  
Infrared Spectroscopy ◽  
Fungal Pathogens ◽  
Near Infrared ◽  
Lemon Juice ◽  
Advanced Materials ◽  
Atomic Force ◽  
Transmission Electron ◽  
Silver Nanocomposite ◽  
Antioxidant And Antimicrobial Activity ◽  
Antimicrobial And Antioxidant Activity

Nanoparticles are important advanced materials with numerous uses in a variety of fields. Novel antibacterial nanocomposites with synergistic capabilities can be created by combining metal nanoparticles with biopolymers of various functionalities. This research evaluates an antimicrobial and antioxidant-rich chitosan-based silver nanocomposite synthesized by using citrus lemon extract as a reducing and capping agent. UV-vis spectrophotometer, scanning electron microscope, elemental dispersive analysis, X-ray diffraction assay, atomic force microscope, Fourier transform infrared spectroscopy, UV-near infrared spectroscopy, and transmission electron microscopy were used to characterize the chitosan-based silver nanocomposite (CS-Ag nanocomposite). The nanocomposite synthesized is used to demonstrate antioxidant and antimicrobial activity against fungal pathogens.

scholarly journals Effect of Annealing on the ZnS Nanocrystals Prepared by Chemical Precipitation Method

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Nadana Shanmugam ◽  
Shanmugam Cholan ◽  
Natesan Kannadasan ◽  
Kannadasan Sathishkumar ◽  
G. Viruthagiri
Keyword(s):  
Chemical Precipitation ◽  
Chemical Precipitation Method ◽  
Precipitation Method ◽  
X Ray Diffraction ◽  
Visible Absorption ◽  
Atomic Force ◽  
Transmission Electron ◽  
Different Temperatures ◽  
Uv Visible ◽  
Dta Curves

Nanocrystals of ZnS have been synthesized through simple chemical precipitation method using thiourea as sulphur source. The synthesized products were annealed at different temperatures in the range of 200–800∘C. The as-synthesized and annealed samples were characterized by X-ray diffraction (XRD), UV-Visible absorption (UV-Vis), and room temperature photoluminescence (PL) measurements. The morphological features of ZnS annealed at 200 and 500∘C were studied by atomic force microscope (AFM) and transmission electron microscope (TEM) techniques. The phase transformation of ZnS and formation of ZnO were confirmed by thermogravimetric (TG) and differential thermal analysis (DTA) curves.

Preparation and Wide Tunable Band-Gap Energies of PbTe Nanocrystals Using Glycerin as a Capping Ligand

2014 ◽  
Vol 904 ◽  
pp. 81-85
Author(s):  
Xing Li Ren ◽  
Xing Rong Jiang
Keyword(s):  
Band Gap ◽  
Blue Shift ◽  
Visible Range ◽  
X Ray Diffraction ◽  
Size Dependent ◽  
Near Ir ◽  
Transmission Electron ◽  
Novel Method ◽  
Uv Visible ◽  
Tunable Band Gap

PbTe nanocrystals (NCs) have been synthesized by a novel method at low temperature. Pb acetate being solved in glycerol and Te in TOP solution were used as the precursors for the preparation of PbTe nanocrystals. The as-prepared products were characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), UVvis absorption, Fourier transform infrared spectroscopy (FTIR). These data, together with analysis of the absorption spectra, allowed us to observe the size dependence of the peaks in the absorption spectrum. The size-dependent optical spectra of the PbTe nanocrystals exhibits wide tunable band gap energies varying from UV visible range to near IR region, which corresponds to a huge blue shift of 3.0 eV in comparison to the bulk counterpart. Keywords: 1. PbTe nanocrystals, 2. optical properties, 3. wide tunable band gap, 4. microstructure

scholarly journals Photometric Observations of Aerosol Optical Properties and Emission Flux Rates of Stromboli Volcano Plume during the PEACETIME Campaign

2021 ◽  
Vol 13 (19) ◽  
pp. 4016
Author(s):  
Pasquale Sellitto ◽  
Giuseppe Salerno ◽  
Jean-François Doussin ◽  
Sylvain Triquet ◽  
François Dulac ◽  
...  
Keyword(s):  
Optical Properties ◽  
Near Infrared ◽  
Visible Range ◽  
Infrared Range ◽  
Emission Flux ◽  
Stromboli Volcano ◽  
Aerosol Emission ◽  
Photometric Observations ◽  
Sulphate Aerosols ◽  
Aerosol Emissions

The characterisation of aerosol emissions from volcanoes is a crucial step towards the assessment of their importance for regional air quality and regional-to-global climate. In this paper we present, for the first time, the characterisation of aerosol emissions of the Stromboli volcano, in terms of their optical properties and emission flux rates, carried out during the PEACETIME oceanographic campaign. Using sun-photometric observations realised during a near-ideal full plume crossing, a plume-isolated aerosol optical depth of 0.07–0.08 in the shorter-wavelength visible range, decreasing to about 0.02 in the near infrared range, was found. An Ångström exponent of 1.40 ± 0.40 was also derived. This value may suggest the dominant presence of sulphate aerosols with a minor presence of ash. During the crossing, two separate plume sections were identified, one possibly slightly affected by ash coming from a mild explosion, and the other more likely composed of pure sulphate aerosols. Exploiting the full crossing scan of the plume, an aerosol emission flux rate of 9–13 kg/s was estimated. This value was 50% larger than for typical passively degassing volcanoes, thus pointing to the importance of mild explosions for aerosol emissions in the atmosphere.

scholarly journals Methodological Basis of The UAVs Use for the Weed Detection

2018 ◽  
Keyword(s):  
Electromagnetic Waves ◽  
Near Infrared ◽  
Classification Method ◽  
Likelihood Method ◽  
Cultivated Plants ◽  
Visible Range ◽  
Infrared Range ◽  
Weed Detection ◽  
Weight Method ◽  
Remote Observation

Purpose. To work out methodological approaches to the use of quadcopters for weeds assesment. Methods. The shooting was carried out using DJI Phantom Vision 2+ and LadyBug Copper Dot. The LadyBug was shoted in the visible and near-infrared range using the 12-megapixel S100 NDVI UAV-Kit camera with elevations: 20 m, 40 m and 60 m. The DJI Phantom Vision 2+ was shot in the visible range of the GoPro 14 megapixel camera altitudes: 10 m, 15 m, 30 m and 60 m. Decryption of photographs was carried out using the controlled classification method in QGIS and TNTmips programs. Weed accounting was performed on control sites 1m2 by weight method, taking into account their qualitative composition. Results. It is shown that the best results of weed recognition during decoding of images was obtained by the use of controlled classification according to the maximum likelihood method under conditions of shooting from heights up to 40 m. In order to improve the recognition of weeds and separate their image from images of cultivated plants, it is expedient to use the object-oriented analysis. At the stage of sunflower budding, about 30% of the weeds are closed from the remote observation, which led to an automatic underestimation of number of weeds. Conclusions. In order to evaluate the crop contamination, it is possible to successfully use the data from UAVs in a visible range of electromagnetic waves under low altitudes (up to 40 meters) and the use of a controlled classification method for decoding images. For the recognition of weeds, the images in the infrared range do not have advantages over images in the visible range. It is necessary to additionally apply ground-based control of weeds to assess the proportion of "hidden" from remote observation of weeds.

scholarly journals Astaxanthin as a new Raman probe for biosensing of specific subcellular lipidic structures: can we detect lipids in cells under resonance conditions?

2020 ◽  
Author(s):  
Krzysztof Czamara ◽  
Adriana Adamczyk ◽  
Marta Stojak ◽  
Basseem Radwan ◽  
Malgorzata Baranska
Keyword(s):  
Near Infrared ◽  
Resonance Excitation ◽  
Live Cells ◽  
Visible Range ◽  
Infrared Range ◽  
Dependent Manner ◽  
Chromophore Group ◽  
Group A ◽  
Raman Probe ◽  
Near Infrared Range

AbstractHere we report a new Raman probe for cellular studies on lipids detection and distribution. It is (3S, 3'S)-astaxanthin (AXT), a natural xanthophyll of hydrophobic properties and high solubility in lipids. It contains a chromophore group, a long polyene chain of eleven conjugated C=C bonds including two in the terminal rings, absorbing light in the visible range that coincides with the excitation of lasers commonly used in Raman spectroscopy for studying of biological samples. Depending on the laser, resonance (excitation in the visible range) or pre-resonance (the near infrared range) Raman spectrum of astaxanthin is dominated by bands at ca. 1008, 1158, and 1520 cm−1 that now can be also a marker of lipids distribution in the cells. We showed that AXT accumulates in lipidic structures of endothelial cells in time-dependent manner that provides possibility to visualize e.g. endoplasmic reticulum, as well as nuclear envelope. As a non-toxic reporter, it has a potential in the future studies on e.g. nucleus membranes damage in live cells in a very short measuring time.

Progress in design, nanofabrication and performance of metalenses

2021 ◽  
Author(s):  
Zhenghao WANG ◽  
Yongling WU ◽  
Dongfeng QI ◽  
Wenhui YU ◽  
Hongyu ZHENG
Keyword(s):  
High Resolution ◽  
Near Infrared ◽  
Visible Range ◽  
Infrared Range ◽  
High Dispersion ◽  
High Resolution Imaging ◽  
Direct Writing ◽  
Nanoscale Structures ◽  
Resolution Imaging ◽  
And Performance

Abstract Metalens has been shown to overcome the diffraction limit of conventional optical lenses to achieve sub-wavelength resolution. Due to its planar structure and lightweight, metalens has the potential applications in the manufacture of flat lenses for cameras and other high resolution imaging optics. However, currently reported metalenses have low focusing efficiencies: 26% - 68% in THz and GHz range, 1% - 91% in near infrared range (NIR), and 5% - 91.6% in the visible range. Far field imaging in the visible light is essential for use in camera and mobile phones, which requires a complex metalens structure with multi-layers of alternating metal and dielectric layers. Most of the reported metalenses work in a single wavelength, mainly due to the high dispersion characteristics of the diffractive metalenses. It remains a challenge to realize high resolution imaging for a wide wavelength band in particular in the visible range. In this review, we report the state-of-the-art in metalens design principle, types of nanoscale structures, and various fabrication processes. We introduce femtosecond laser direct writing based on two-photon polymerization as an emerging nanofabrication technology. We provide an overview of the optical performance of the recently-reported metalenses and elaborate the major research and engineering challenges and future prospects.

scholarly journals Ga-Doped ZnO Coating—A Suitable Tool for Tuning the Electrode Properties in the Solar Cells with CdS/ZnS Core-Shell Quantum Dots

Crystals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 137
Author(s):  
Mariya Aleksandrova ◽  
Tatyana Ivanova ◽  
Velichka Strijkova ◽  
Tsvetozar Tsanev ◽  
Ajaya Kumar Singh ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Quantum Dots ◽  
Solar Cells ◽  
Indium Tin Oxide ◽  
Near Infrared ◽  
Optical Transmittance ◽  
Visible Range ◽  
Infrared Range ◽  
Layer System ◽  
Doped Zno

Two layer system from sputtered indium tin oxide (ITO) and gallium doped zinc oxide (Ga:ZnO, GZO) were studied for transparency in the visible electromagnetic range, reflectivity in the near infrared range, conductivity and valent band for a solar cells with quantum dots. The bi-layer coatings produced at optimized oxygen partial pressure, films thickness and surface roughness exhibit improved optical properties without worsening the electrical parameters, even if additional oxygen introduction during the reactive sputtering of the GZO. With an average optical transmittance of 91.3% in the visible range, average reflection and resistivity lower than 0.4 × 10−2 Ω.cm, these coatings are suitable for top electrode in the solar cells. The obtained results reveal that multilayered stacks of transparent ITO/Ga-doped ZnO coatings possess relatively low surface roughness (7–9 nm) and appropriate refractive index. The additional oxidation of GZO films induces modification of the film thickness and respectively of their optical performances.

scholarly journals Porphycene Films Grown on Highly Oriented Pyrolytic Graphite: Unveiling Structure–Property Relationship through Combined Reflectance Anisotropy Spectroscopy and Atomic Force Microscopy Investigations

Proceedings ◽  
2021 ◽  
Vol 56 (1) ◽  
pp. 44
Author(s):  
Marta Penconi ◽  
Lorenzo Ferraro ◽  
Jacek Waluk ◽  
Lamberto Duò ◽  
Franco Ciccacci ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Near Infrared ◽  
Pyrolytic Graphite ◽  
Visible Spectral Range ◽  
Visible Range ◽  
Structure Property ◽  
Force Microscopy ◽  
Reflectance Anisotropy ◽  
Atomic Force ◽  
Proper Design

Thin organic films are widely used in sensors, solar cells, and optical devices due to their intense absorption in the visible/near-infrared (IR) region. Shifting, quenching, or reshaping of some spectral features can be achieved by chemical functionalization of the molecules, whereas an anisotropic fingerprint due to preferential molecular alignment can be induced via a proper design and/or preparation of the substrate. Recently, we investigated the optical response of thin films of porphycene to acidification. With respect to the well-known and closely related tetraphenyl porphyrin, porphycene has the clear advantage of being optically active in the full visible range, and this makes visible by naked eye the immediate change of the film from brilliant blue-turquoise to green when exposed to HCl vapors. In this work, by exploiting a homemade reflectance anisotropy spectroscopy (RAS) apparatus, we explore possible optical anisotropies in the visible spectral range of porphycene films and relate them to the film morphology analyzed by atomic force microscopy (AFM).

scholarly journals Study of crystallographic, optical and sensing properties of Na2WO4 films deposited by thermal evaporation with several thickness

2019 ◽  
Vol 37 (4) ◽  
pp. 590-598
Author(s):  
B. Abdallah ◽  
M. Kakhia ◽  
S. Abou Shaker
Keyword(s):  
Film Thickness ◽  
Photoelectron Spectroscopy ◽  
Near Infrared ◽  
Thermal Evaporation ◽  
Infrared Range ◽  
Sensing Properties ◽  
Force Microscopy ◽  
Atomic Force ◽  
Average Transmittance ◽  
Evaporation Technique

AbstractNa2WO4 films have been grown at 400 °C using thermal evaporation technique. Their structural properties were characterized by XRD, while their chemical composition was verified by both EDX and X-ray photoelectron spectroscopy (XPS). The evolution of crystallinity was studied as a function of film thickness that ranged from 500 nm to 3000 nm. The grain size increased with increasing film thickness. The surface morphology of the prepared films was studied using scanning electron microscope (SEM) and atomic force microscopy (AFM). It has been observed that the average transmittance of samples in the visible and near infrared range has varied from 90 % to 78 % with the film thickness. The optical band gap of the Na2WO4 films varied from 3.8 eV to 4.1 eV. The crystalline size increased with increasing thickness and showed better sensing response to gases. Thus, this study confirmed the possibility of using Na2WO4 thick films as a sensor element for detection of ethanol (C2H5OH), acetone (C3H6O) methanol (CH3OH) and ammonia hydroxide (NH4OH) vapor at room temperature, where thicker films exhibited sensing properties with a maximum sensitivity at 25 °C in air, especially for NH4OH.

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