Plasma impact on structural, morphological and optical properties of copper acetylacetonate thin films.

PubMed

Abdel-Khalek, H; El-Samahi, M I; El-Mahalawy, Ahmed M

2018-06-15

The influence of plasma exposure on structural, morphological and optical properties of copper (II) acetylacetonate thin films deposited by thermal evaporation technique was investigated. Copper (II) acetylacetonate as-grown thin films were exposed to the atmospheric plasma for different times. The exposure of as-grown cu(acac) 2 thin film to atmospheric plasma for 5min modified its structural, morphological and optical properties. The effect of plasma exposure on structure and roughness of cu(acac) 2 thin films was evaluated by XRD and AFM techniques, respectively. The XRD results showed an increment in crystallinity due to exposure for 5min, but, when the exposure time reaches 10min, the film was transformed to an amorphous state. The AFM results revealed a strong modification of films roughness when the average roughness decreased from 63.35nm to ~1nm as a result of interaction with plasma. The optical properties of as-grown and plasma exposured cu(acac) 2 thin films were studied using spectrophotometric method. The exposure of cu(acac) 2 thin films to plasma produced the indirect energy gap decrease from 3.20eV to 2.67eV for 10min exposure time. The dispersion parameters were evaluated in terms of single oscillator model for as-grown and plasma exposured thin films. The influence of plasma exposure on third order optical susceptibility was studied. Copyright © 2018 Elsevier B.V. All rights reserved.

Identification of muscle necrosis in the mdx mouse model of Duchenne muscular dystrophy using three-dimensional optical coherence tomography

NASA Astrophysics Data System (ADS)

Klyen, Blake R.; Shavlakadze, Thea; Radley-Crabb, Hannah G.; Grounds, Miranda D.; Sampson, David D.

2011-07-01

Three-dimensional optical coherence tomography (3D-OCT) was used to image the structure and pathology of skeletal muscle tissue from the treadmill-exercised mdx mouse model of human Duchenne muscular dystrophy. Optical coherence tomography (OCT) images of excised muscle samples were compared with co-registered hematoxylin and eosin-stained and Evans blue dye fluorescence histology. We show, for the first time, structural 3D-OCT images of skeletal muscle dystropathology well correlated with co-located histology. OCT could identify morphological features of interest and necrotic lesions within the muscle tissue samples based on intrinsic optical contrast. These findings demonstrate the utility of 3D-OCT for the evaluation of small-animal skeletal muscle morphology and pathology, particularly for studies of mouse models of muscular dystrophy.

Developmental and morphological studies in Japanese medaka with ultra-high resolution optical coherence tomography

PubMed Central

Gladys, Fanny Moses; Matsuda, Masaru; Lim, Yiheng; Jackin, Boaz Jessie; Imai, Takuto; Otani, Yukitoshi; Yatagai, Toyohiko; Cense, Barry

2015-01-01

We propose ultra-high resolution optical coherence tomography to study the morphological development of internal organs in medaka fish in the post-embryonic stages at micrometer resolution. Different stages of Japanese medaka were imaged after hatching in vivo with an axial resolution of 2.8 µm in tissue. Various morphological structures and organs identified in the OCT images were then compared with the histology. Due to the medaka’s close resemblance to vertebrates, including humans, these morphological features play an important role in morphogenesis and can be used to study diseases that also occur in humans. PMID:25780725

Synthesis and characterization of Graphene oxide/Zinc oxide nanorods sandwich structure

NASA Astrophysics Data System (ADS)

Boukhoubza, I.; Khenfouch, M.; Achehboune, M.; Mouthudi, B.; Zorkani, I.; Jorio, A.

2018-03-01

Graphene-ZnO nanostructures composite materials have been used as very efficient candidates for various optoelectronic applications. Nowadays, the composite structure formation of ZnO nanostructures with graphene or graphene oxide is a novel, cost effective and efficient approach to control the morphology, surface defect states, band gap of ZnO nanocrystals. In this paper, we have prepared ZnO nanorods between two layers graphene oxide (GO/ZnO NRs/GO) via a simple hydrothermal method. Their morphology, structural and optical properties have been investigated. The obtained results of our composites GO/ZnO NRs/GO presented here showing an enhancement in the structural and optical properties. Thus may hold great promise to the development of the optoelectronic devices.

Fractal bimetallic plasmonic structures obtained by laser deposition of colloidal nanoparticles

NASA Astrophysics Data System (ADS)

Bukharov, D. N.; Arakelyan, S. M.; Kutrovskaya, S. V.; Kucherik, A. O.; Osipov, A. V.; Istratov, A. V.; Vartanyan, T. A.; Itina, T. E.; Kavokin, A. V.

2017-09-01

We produce bimetallic Au:Ag thin films by laser irradiation of the mixed solutions. After several laser scans, granular nanometric films are found to grow with a well-controlled composition, thickness and morphology. By changing laser scanning parameters, the film morphology can be varied from island structures to quasi-periodic arrays. The optical properties of the deposited structures are found to depend on the film composition, thickness and spacing between the particles. The transmittance spectra of the deposited films are shown to be governed by their morphology.

AFM imaging of natural optical structures

NASA Astrophysics Data System (ADS)

Dallaeva, Dinara; Tománek, Pavel; Prokopyeva, Elena; Kaspar, Pavel; Grmela, Lubomír.; Škarvada, Pavel

2015-01-01

The colors of some living organisms assosiated with the surface structure. Irridesence butterfly wings is an example of such coloration. Optical effects such as interference, diffraction, polarization are responsible for physical colors appearance. Alongside with amazing beauty this structure represent interest for design of optical devices. Here we report the results of morphology investigation by atomic force microscopy. The difference in surface structure of black and blue wings areas is clearly observed. It explains the angle dependence of the wing blue color, since these micrometer and sub-micrometer quasiperiodical structures could control the light propagation, absorption and reflection.

Experimental Study of Acid Treatment Toward Characterization of Structural, Optical, and Morphological Properties of TiO2-SnO2 Composite Thin Film

NASA Astrophysics Data System (ADS)

Fajar, M. N.; Hidayat, R.; Triwikantoro; Endarko

2018-04-01

The TiO2-SnO2 thin film with single and double-layer structure has successfully synthesized on FTO (Fluorine-doped Tin Oxide) substrate using the screen printing technique. The structural, optical, and morphological properties of the film were investigated by XRD, UV-Vis, and SEM, respectively. The results showed that the single and double-layer structure of TiO2-SnO2 thin film has mixed phase with a strong formation of casseritte phase. The acid treatment effect on TiO2-SnO2 thin film decreases the peak intensity of anatase phase formation and thin film’s absorbance values. The morphological study is also revealed that the single layer TiO2-SnO2 thin film had a more porous nature and decreased particle size distribution after acid treatment, while the double-layer TiO2-SnO2 thin film Eroded due to acid treatment.

Influence of post-deposition annealing on structural, morphological and optical properties of copper (II) acetylacetonate thin films.

PubMed

Abdel-Khalek, H; El-Samahi, M I; El-Mahalawy, Ahmed M

2018-05-21

In this study, the effect of thermal annealing under vacuum conditions on structural, morphological and optical properties of thermally evaporated copper (II) acetylacetonate, cu(acac) 2 , thin films were investigated. The copper (II) acetylacetonate thin films were deposited using thermal evaporation technique at vacuum pressure ~1 × 10 -5  mbar. The deposited films were thermally annealed at 323, 373, 423, and 473 K for 2 h in vacuum. The thermogravimetric analysis of cu(acac) 2 powder indicated a thermal stability of cu(acac) 2 up to 423 K. The effects of thermal annealing on the structural properties of cu(acac) 2 were evaluated employing X-ray diffraction method and the analysis showed a polycrystalline nature of the as-deposited and annealed films with a preferred orientation in [1¯01] direction. Fourier transformation infrared (FTIR) technique was used to negate the decomposition of copper (II) acetylacetonate during preparation or/and annealing up to 423 K. The surface morphology of the prepared films was characterized by means of field emission scanning electron microscopy (FESEM). A significant enhancement of the morphological properties of cu(acac) 2 thin films was obtained till the annealing temperature reaches 423 K. The variation of optical constants that estimated from spectrophotometric measurements of the prepared thin films was investigated as a function of annealing temperature. The annealing process presented significantly impacted the nonlinear optical properties such as third-order optical susceptibility χ (3) and nonlinear refractive index n 2 of cu(acac) 2 thin films. Copyright © 2018 Elsevier B.V. All rights reserved.

Impact of phytoplankton community structure and function on marine particulate optical properties

NASA Astrophysics Data System (ADS)

McFarland, Malcolm Neil

Phytoplankton are an ecologically important and diverse group of organisms whose distribution, abundance, and population dynamics vary significantly over small spatial (cm) and temporal (minutes) scales in the coastal ocean. Our inability to observe phytoplankton community structure and function at these small scales has severely limited our understanding of the fundamental ecological and evolutionary mechanisms that drive phytoplankton growth, mortality, adaptation and speciation. The goal of this dissertation was to enhance our understanding of phytoplankton ecology by improving in situ observational techniques based on the optical properties of cells, colonies, populations, and communities. Field and laboratory studies were used to determine the effects of phytoplankton species composition, morphology, and physiology on the inherent optical properties of communities and to explore the adaptive significance of bio-optically important cellular characteristics. Initial field studies found a strong association between species composition and the relative magnitude and shape of particulate absorption, scattering, and attenuation coefficient spectra. Subsequent field studies using scanning flow cytometry to directly measure optically important phytoplankton and non-algal particle characteristics demonstrated that the size and pigment content of large (>20 microm) phytoplankton cells and colonies vary significantly with the slope of particulate attenuation and absorption spectra, and with the ratio of particulate scattering to absorption. These relationships enabled visualization of phytoplankton community composition and mortality over small spatial and temporal scales derived from high resolution optical measurements acquired with an autonomous profiling system. Laboratory studies with diverse uni-algal cultures showed that morphological and physiological characteristics of cells and colonies can account for ˜30% of the optical variation observed in natural communities and that complex morphologies and low intracellular pigment concentrations minimize pigment self-shading that could otherwise limit bio-optical fitness. These results demonstrate that optical properties reveal detailed information about the distribution, abundance, morphology, and physiology of phytoplankton that can help explain their ecological dynamics over small spatial scales and the bio-optical function of diverse forms in the ocean.

LASERS IN MEDICINE: Structure of matrices for the transformation of laser radiation by biofractals

NASA Astrophysics Data System (ADS)

Angel'skii, O. V.; Ushenko, A. G.; Arkhelyuk, A. D.; Ermolenko, S. B.; Burkovets, D. N.

1999-12-01

The changes in the state of polarisation of laser radiation transformed by biofractal objects are examined. The orientational angular structure of the matrix elements of the operator representing the optical properties of biofractals with different morphological structures (mineralised collagen fibres and myosin bundles) is investigated. An optical model for the description of fractal laser fields under the conditions of single light scattering is proposed.

A novel approach to enhancement of surface properties of CdO films by using surfactant: dextrin

NASA Astrophysics Data System (ADS)

Sahin, Bünyamin; Bayansal, Fatih; Yüksel, Mustafa

2015-12-01

We studied the effect of an organic surfactant, dextrin, concentration on structural, morphological and optical properties of nanostructured CdO films deposited on glass substrates by using an easy and low-cost SILAR method. Microstructures of the nanostructured CdO films were optimized by adjusting dextrin concentration. XRD, SEM and UV-Vis Spectroscopy were used to study phase structure, surface morphology and optical properties of CdO films. Furthermore, effects of dextrin concentration on the surface roughness characteristics of CdO samples were reported. The results showed that the presence of organic surfactant highly affected the physical properties of CdO nanomaterials.

Acoustical, morphological and optical properties of oral rehydration salts (ORS)

NASA Astrophysics Data System (ADS)

George, Preetha Mary; Jayakumar, S.; Divya, P.; Subhashree, N. S.; Ahmed, M. Anees

2015-06-01

Ultrasonic velocity, density and viscosity were measured in different concentrations of oral rehydration salts (ORS) at room temperature 303 k. From the experimental data other related thermodynamic parameters, viz adiabatic compressibility, intermolecular free length, acoustic impedence, relaxation time are calculated. The experimental data were discussed in the light of molecular interaction existing in the liquid mixtures. The results have been discussed in terms of solute-solvent interaction between the components. Structural characterization is important for development of new material. The morphology, structure and grain size of the samples are investigated by SEM. The optical properties of the sample have been studied using UV Visible spectroscopy.

Synthesis and Characterization of Molybdenum Doped ZnO Thin Films by SILAR Deposition Method

NASA Astrophysics Data System (ADS)

Radha, R.; Sakthivelu, A.; Pradhabhan, D.

2016-08-01

Molybdenum (Mo) doped zinc oxide (ZnO) thin films were deposited on the glass substrate by Successive Ionic Layer Adsorption and Reaction (SILAR) deposition method. The effect of Mo dopant concentration of 5, 6.6 and 10 mol% on the structural, morphological, optical and electrical properties of n-type Mo doped ZnO films was studied. The X-ray diffraction (XRD) results confirmed that the Mo doped ZnO thin films were polycrystalline with wurtzite structure. The field emission scanning electron microscopy (FESEM) studies shows that the surface morphology of the films changes with Mo doping. A blue shift of the optical band gap was observed in the optical studies. Effect of Mo dopant concentration on electrical conductivity was studied and it shows comparatively high electrical conductivity at 10 mol% of Mo doping concentration.

Enhanced photo response of mesoporous nanostructured CdS thin film via electrospray aerosol deposition technique

NASA Astrophysics Data System (ADS)

Logu, T.; Soundarrajan, P.; Sankarasubramanian, K.; Sethuraman, K.

2018-04-01

In this work, a high crystalline and mesoporous nanostructured cadmium sulfide (CdS) thin film was successfully grown on the FTO substrates using facile Electrospray Aerosol Deposition (ESAD) technique. The structural, optical, morphological and electrical properties of CdS thin film have been systematically examined. CdS thin film exhibits the hexagonal wurtzite crystal structure with polycrystalline nature. The optical band gap energy of the prepared film was estimated from the Tauc plot and is 2.43 eV. The SEM and AFM images show that the well-interconnected CdS nanoparticles gives mesoporous like morphology. The fine aerosol generated from the ESAD process induces the alteration in the surface morphological structure of deposited CdS film that consequences in enhanced electrical and photo-physical properties. The photoconductivity of the sample has been studied which demonstrates significant photo current. The present study predicts that mesoporous nanostructured CdS thin film would be given a special interest for optoelectronic applications.

Fluorine-doped NiO nanostructures: Structural, morphological and spectroscopic studies

NASA Astrophysics Data System (ADS)

Singh, Kulwinder; Kumar, Manjeet; Singh, Dilpreet; Singh, Manjinder; Singh, Paviter; Singh, Bikramjeet; Kaur, Gurpreet; Bala, Rajni; Thakur, Anup; Kumar, Akshay

2018-05-01

Nanostructured NiO has been prepared by co-precipitation method. In this study, the effect of fluorine doping (1, 3 and 5 wt. %) on the structural, morphological as well as optical properties of NiO nanostructures has been studied. X-ray diffraction (XRD) has employed for studying the structural properties. Cubic crystal structure of NiO was confirmed by the XRD analysis. Crystallite size increased with increase in doping concentration. Nelson-Riley factor (NRF) analysis indicated the presence of defect states in the synthesized samples. Field emission scanning electron microscopy showed the spherical morphology of the synthesized samples and also revealed that the particle size varied with dopant content. The optical properties were studied using UV-Visible Spectroscopy. The results indicated that the band gap energy of the synthesized nanostructures decreased with increase in doping concentration upto 3% but increased as the doping concentration was further raised to 5%. This can be ascribed to the defect states variations in the synthesized samples. The results suggested that the synthesized nanostructures are promising candidate for optoelectronic as well as gas sensing applications.

Low-temperature growth of aligned ZnO nanorods: effect of annealing gases on the structural and optical properties.

PubMed

Umar, Ahmad; Hahn, Yoon-Bong; Al-Hajry, A; Abaker, M

2014-06-01

Aligned ZnO nanorods were grown on ZnO/Si substrate via simple aqueous solution process at low-temperature of - 65 degrees C by using zinc nitrate and hexamethylenetetramine (HMTA). The detailed morphological and structural properties measured by FESEM, XRD, EDS and TEM confirmed that the as-grown nanorods are vertically aligned, well-crystalline possessing wurtzite hexagonal phase and grown along the [0001] direction. The room-temperature photoluminescence spectrum of the grown nanorods exhibited a strong and broad green emission and small ultraviolet emission. The as-prepared ZnO nanorods were post-annealed in nitrogen (N2) and oxygen (O2) environments and further characterized in terms of their morphological, structural and optical properties. After annealing the nanorods exhibit well-crystallinity and wurtzite hexagonal phase. Moreover, by annealing the PL spectra show the enhancement in the UV emission and suppression in the green emission. The presented results demonstrate that simply by post-annealing process, the optical properties of ZnO nanostructures can be controlled.

Structural, morphological and optical properties of PEDOT:PSS/QDs nano-composite films prepared by spin-casting

NASA Astrophysics Data System (ADS)

Najeeb, Mansoor Ani; Abdullah, Shahino Mah; Aziz, Fakhra; Ahmad, Zubair; Rafique, Saqib; Wageh, S.; Al-Ghamdi, Ahmed A.; Sulaiman, Khaulah; Touati, Farid; Shakoor, R. A.; Al-Thani, N. J.

2016-09-01

This paper describes the structural, morphological and optical properties of the nano-composite of poly (3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) and quantum dots (QDs). The ZnSe and CdSe QDs have been synthesized, with the aid of Mercaptoacetic acid (MAA), by a colloidal method with an average size of 5 to 7 nm. QDs have been embedded in PEDOT:PSS using a simple solution processing approach and has been deposited as thin films by spin coating technique. The QDs embedded PEDOT:PSS enhances the light absorption spectra of samples, prominently in terms of absorption intensity which may consequently improve sensitivity of the optoelectronic devices.

Effect of growth time on the structure, morphology and optical properties of hydrothermally synthesized TiO2 nanorod thin films

NASA Astrophysics Data System (ADS)

Mohapatra, A. K.; Nayak, J.

2018-05-01

Titanium dioxide (TiO2) nanorod thin films were deposited on fluorine doped tin oxide coated glass substrates by a single step rapid hydrothermal process. The concentration of the precursor, the temperature of the reaction mixture were optimized in order to enhance the rate of deposition. Unlike the previously reported hydrothermal treatment for 24 - 48 h, the deposition of well aligned titanium dioxide nanorods was achieved in a short time such as 3 - 8 h. The crystal structure of the films were investigated by X-rays diffraction. The morphology of the nanorod films were studied with scanning electron microscopy. The optical properties were studied by photoluminescence spectroscopy.

Revealing Nanostructures through Plasmon Polarimetry.

PubMed

Kleemann, Marie-Elena; Mertens, Jan; Zheng, Xuezhi; Cormier, Sean; Turek, Vladimir; Benz, Felix; Chikkaraddy, Rohit; Deacon, William; Lombardi, Anna; Moshchalkov, Victor V; Vandenbosch, Guy A E; Baumberg, Jeremy J

2017-01-24

Polarized optical dark-field spectroscopy is shown to be a versatile noninvasive probe of plasmonic structures that trap light to the nanoscale. Clear spectral polarization splittings are found to be directly related to the asymmetric morphology of nanocavities formed between faceted gold nanoparticles and an underlying gold substrate. Both experiment and simulation show the influence of geometry on the coupled system, with spectral shifts Δλ = 3 nm from single atoms. Analytical models allow us to identify the split resonances as transverse cavity modes, tightly confined to the nanogap. The direct correlation of resonance splitting with atomistic morphology allows mapping of subnanometre structures, which is crucial for progress in extreme nano-optics involving chemistry, nanophotonics, and quantum devices.

Acoustical, morphological and optical properties of oral rehydration salts (ORS)

DOE Office of Scientific and Technical Information (OSTI.GOV)

George, Preetha Mary, E-mail: preethageoti@gmail.com, E-mail: jayakumars030@gmail.com; Divya, P.; Jayakumar, S., E-mail: preethageoti@gmail.com, E-mail: jayakumars030@gmail.com

Ultrasonic velocity, density and viscosity were measured in different concentrations of oral rehydration salts (ORS) at room temperature 303 k. From the experimental data other related thermodynamic parameters, viz adiabatic compressibility, intermolecular free length, acoustic impedence, relaxation time are calculated. The experimental data were discussed in the light of molecular interaction existing in the liquid mixtures. The results have been discussed in terms of solute-solvent interaction between the components. Structural characterization is important for development of new material. The morphology, structure and grain size of the samples are investigated by SEM. The optical properties of the sample have been studied usingmore » UV Visible spectroscopy.« less

Effect of annealing on structure, morphology and optoelectronic properties of nanocrystalline CuO thin films

NASA Astrophysics Data System (ADS)

Jundale, D. M.; Pawar, S. G.; Patil, S. L.; Chougule, M. A.; Godse, P. R.; Patil, V. B.

2011-10-01

The nanocrystalline CuO thin films were prepared on glass substrates by the sol-gel method. The structural, morphological, electrical and optical properties of CuO thin films, submitted to an annealing treatment in the 400-700 °C ranges are studied by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Four Probe Technique and UV-visible spectroscopic. XRD measurements show that all the films are crystallized in the monoclinic phase and present a random orientation. Four prominent peaks, corresponding to the (110) phase (2θ≈32.70°), (002) phase (2θ≈35.70°), (111) phase (2θ≈38.76°) and (202) phase (2θ≈49.06°) appear on the diffractograms. The crystallite size increases with increasing annealing temperature. These modifications influence the microstructure, electrical and optical properties. The optical band gap energy decreases with increasing annealing temperature. These mean that the optical quality of CuO films is improved by annealing.

Study of lattice strain and optical properties of nanocrystalline SnO2

NASA Astrophysics Data System (ADS)

Ahmad, Naseem; Khan, Shakeel; Bhargava, Richa; Ansari, Mohd Mohsin Nizam

2018-05-01

Nanocrystalline SnO2 has been synthesized by co-precipitation method by using two solvents (water and ethylene glycol). The structure and surface morphology were investigated using XRD and scanning electron microscope (SEM). The optical properties were studied using diffused reflectance spectroscopy (DRS). From the XRD analysis, the prepared materials are found to be pure crystalline with tetragonal rutile structure. The lattice strain and crystallite size, were calculated using Williamson-Hall method, are found to be 0.00413 & 16.3 nm in water assisted SnO2 and 0.00495 & 35.6 nm for EG assisted SnO2. Study of surface morphology of the samples was carried out using SEM. It has been seen that the solvents which are used in synthesis can also alter the optical properties of the materials. The optical band gap of the water based SnO2 and EG based SnO2 are found to be 3.92eV and 3.86eV respectively.

Galaxy Zoo: Infrared and Optical Morphology

NASA Astrophysics Data System (ADS)

Carla Shanahan, Jesse; Lintott, Chris; Zoo, Galaxy

2018-01-01

We present the detailed, visual morphologies of approximately 60,000 galaxies observed by the UKIRT Infrared Deep Sky Survey and then classified by participants in the Galaxy Zoo project. Our sample is composed entirely of nearby objects with redshifts of z ≤ 0.3, which enables us to robustly analyze their morphological characteristics including smoothness, bulge properties, spiral structure, and evidence of bars or rings. The determination of these features is made via a consensus-based analysis of the Galaxy Zoo project data in which inconsistent and outlying classifications are statistically down-weighted. We then compare these classifications of infrared morphology to the objects’ optical classifications in the Galaxy Zoo 2 release (Willett et al. 2013). It is already known that morphology is an effective tool for uncovering a galaxy’s dynamical past, and previous studies have shown significant correlations with physical characteristics such as stellar mass distribution and star formation history. We show that majority of the sample has agreement or expected differences between the optical and infrared classifications, but also present a preliminary analysis of a subsample of objects with striking discrepancies.

Influence Al doped ZnO nanostructure on structural and optical properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ramelan, Ari Handono, E-mail: aramelan@mipa.uns.ac.id; Wahyuningsih, Sayekti; Chasanah, Uswatul

2016-04-19

The preparation of Al-doped ZnO (AZO) thin films prepared by the spin-coating method was reported. Preparation of AZO was conducted by annealing treatment at a temperature of 700°C. While the spin-coating process of AZO thin films were done at 2000 and 3000 rpm respectively. The structural properties of ZnO were determined by X- ray diffraction (XRD) analysis. ZnOnanostructure was formed after annealed at atemperature of 400°C.The morphology of ZnO was determined by Scanning Electron Microscopy (SEM) showed the irregular morphology about 30-50µm in size. Al doped on ZnO influenced the optical properties of those material. Increasing Al contain on ZnO causemore » of shifting to the lower wavelength. The optical properties of the ZnO as well as AZO films showed that higher reflectance on the ultraviolet region so those materials were used as anti-reflecting agent.Al addition significantly enhance the optical transparency and induce the blue-shift in optical bandgap of ZnO films.« less

Optical and morphological study of disorder in opals

NASA Astrophysics Data System (ADS)

Palacios-Lidón, E.; Juárez, B. H.; Castillo-Martínez, E.; López, C.

2005-03-01

An optical and morphological study has been carried out to understand the role of intrinsic defects in the optical properties of opal-based photonic crystals. By doping poly(methylmethacrylate) (PMMA) thin-film opals with larger polystyrene (PS) spheres, structural disorder has being generated perturbing the PMMA matrix periodicity. It is shown that this disorder dramatically affects the optical response of the system worsening its photonic properties. It has been found that the effect of doping is highly dependent not only on the concentration but also on the relative size of the dopant with reference to the matrix. Through a detailed scanning electron microscopy inspection, the sort of structural defects involved, derived from the different particle size used, has been characterized. A direct relationship between the observed optical response with the different perturbations generated in the lattice has been found. In addition, from this study it can be concluded that it is possible to grow high quality alloyed photonic crystals, exhibiting intermediate photonic properties between pure PMMA and pure PS opals by simple sphere size matching and variation of the relative concentration of both components.

Evaluation of the Mechanism of the Gold Cluster Growth during Heating of the Composite Gold-Polytetrafluoroethylene Thin Film.

PubMed

Grytsenko, Konstantin; Lozovski, Valeri; Strilchuk, Galyna; Schrader, Sigurd

2012-11-07

Nanocomposite films consisting of gold inclusions in the polytetrafluoroethylene (PTFE) matrix were obtained by thermal vacuum deposition. Annealing of the obtained films with different temperatures was used to measure varying of film morphologies. The dependence of optical properties of the films on their morphology was studied. It was established that absorption and profile of the nanocomposite film obtained by thermal vacuum deposition can be changed with annealing owing to the fact that different annealing temperatures lead to different average particle sizes. A method to calculate the optical properties of nanocomposite thin films with inclusions of different sizes was proposed. Thus, comparison of experimental optical spectra with the spectra obtained during the simulation enables estimating average sizes of inclusions. The calculations give the possibility of understanding morphological changes in the structures.

Hydrothermal temperature effect on crystal structures, optical properties and electrical conductivity of ZnO nanostructures

NASA Astrophysics Data System (ADS)

Dhafina, Wan Almaz; Salleh, Hasiah; Daud, Mohd Zalani; Ghazali, Mohd Sabri Mohd; Ghazali, Salmah Mohd

2017-09-01

ZnO is an wide direct band gap semiconductor and possess rich family of nanostructures which turned to be a key role in the nanotechnology field of applications. Hydrothermal method was proven to be simple, robust and low cost among the reported methods to synthesize ZnO nanostructures. In this work, the properties of ZnO nanostructures were altered by varying temperatures of hydrothermal process. The changes in term of morphological, crystal structures, optical properties and electrical conductivity were investigated. A drastic change of ZnO nanostructures morphology and decreases of 002 diffraction peak were observed as the hydrothermal temperature increased. The band gap of samples decreased as the size of ZnO nanostructure increased, whereas the electrical conductivity had no influence on the band gap value but more on the morphology of ZnO nanostructures instead.

Direct femtosecond laser ablation of copper with an optical vortex beam

DOE Office of Scientific and Technical Information (OSTI.GOV)

Anoop, K. K.; Rubano, A.; Marrucci, L.

Laser surface structuring of copper is induced by laser ablation with a femtosecond optical vortex beam generated via spin-to-orbital conversion of the angular momentum of light by using a q-plate. The variation of the produced surface structures is studied as a function of the number of pulses, N, and laser fluence, F. After the first laser pulse (N=1), the irradiated surface presents an annular region characterized by a corrugated morphology made by a rather complex network of nanometer-scale ridges, wrinkles, pores, and cavities. Increasing the number of pulses (21000) and a deep crater is formed. The nanostructure variation with themore » laser fluence, F, also evidences an interesting dependence, with a coarsening of the structure morphology as F increases. Our experimental findings demonstrate that direct femtosecond laser ablation with optical vortex beams produces interesting patterns not achievable by the more standard beams with a Gaussian intensity profile. They also suggest that appropriate tuning of the experimental conditions (F, N) can allow generating micro- and/or nano-structured surface for any specific application.« less

LASER BIOLOGY AND MEDICINE: Combined application of optical methods to increase the information content of optical coherent tomography in diagnostics of neoplastic processes

NASA Astrophysics Data System (ADS)

Kuranov, R. V.; Sapozhnikova, V. V.; Shakhova, N. M.; Gelikonov, V. M.; Zagainova, E. V.; Petrova, S. A.

2002-11-01

A combined application of optical methods [optical coherent tomography (OCT), cross-polarisation optical coherent tomography, and fluorescence spectroscopy] is proposed for obtaining information on morphological and biochemical changes occurring in tissues in norm and pathology. It is shown that neoplastic and scar changes in esophagus can be distinguished using a combination of polarisation and standard OCT due to the difference between the depolarising properties of the tissues caused by the structural properties of collagenic fibres in stroma. It is shown that OCT combined with fluorescence spectroscopy with the use of 5-aminolevulinic acid is promising for determining the boundaries of carcinoma of the uterine cervix and vulva. It is found that the tumour boundary detected by optical methods coincides with the morphological boundary and extends beyond colposcopically determined boundary by about 2 mm.

Combined application of optical methods to increase the information content of optical coherent tomography in diagnostics of neoplastic processes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kuranov, R V; Sapozhnikova, V V; Shakhova, N M

2002-11-30

A combined application of optical methods [optical coherent tomography (OCT), cross-polarisation optical coherent tomography, and fluorescence spectroscopy] is proposed for obtaining information on morphological and biochemical changes occurring in tissues in norm and pathology. It is shown that neoplastic and scar changes in esophagus can be distinguished using a combination of polarisation and standard OCT due to the difference between the depolarising properties of the tissues caused by the structural properties of collagenic fibres in stroma. It is shown that OCT combined with fluorescence spectroscopy with the use of 5-aminolevulinic acid is promising for determining the boundaries of carcinoma ofmore » the uterine cervix and vulva. It is found that the tumour boundary detected by optical methods coincides with the morphological boundary and extends beyond colposcopically determined boundary by about 2 mm. (laser biology and medicine)« less

Effects of various applied voltages on physical properties of TiO2 nanotubes by anodization method

NASA Astrophysics Data System (ADS)

Hoseinzadeh, T.; Ghorannevis, Z.; Ghoranneviss, M.; Sari, A. H.; Salem, M. K.

2017-09-01

Three steps anodization process is used to synthesize highly ordered and uniform multilayered titanium oxide (TiO2) nanotubes and effect of different anodization voltages are studied on their physical properties such as structural, morphological and optical. The crystalized structure of the synthesized tubes is investigated by X-ray diffractometer analysis. To study the morphology of the tubes, field emission scanning electron microscopy is used, which showed that the wall thicknesses and the diameters of the tubes are affected by the different anodization voltages. Moreover, optical studies performed by diffuse reflection spectra suggested that band gap of the TiO2 nanotubes are also changed by applying different anodization voltages. In this study using physical investigations, an optimum anodization voltage is obtained to synthesize the uniform crystalized TiO2 nanotubes with suitable diameter, wall thickness and optical properties.

Optical and sensing properties of sol-gel derived vanadium pentoxide thin films with porous and dense structures

NASA Astrophysics Data System (ADS)

Babeva, T.; Awala, H.; Grand, J.; Lazarova, K.; Vasileva, M.; Mintova, S.

2018-03-01

The sol-gel and spin-coating methods were used for deposition of thin transparent V2O5 films on optical glass substrates and silicon wafers. Different synthesis and deposition conditions, including synthesis temperatures and post-deposition annealing, were used aiming at obtaining transparent films with high refractive index and good optical quality. The surface morphology and structure of the films were studied by SEM and XRD. The optical properties (refractive index, extinction coefficient and optical band gap) and thickness of the V2O5 films were determined from their transmittance and reflectance spectra. The potential application of the films as building blocks of optical sensors was demonstrated by preparation of multilayered structures comprising both V2O5 and BEA-type zeolite films and testing their response towards acetone vapors.

In vivo assessment of optical properties of melanocytic skin lesions and differentiation of melanoma from non-malignant lesions by high-definition optical coherence tomography.

PubMed

Boone, M A L M; Suppa, M; Dhaenens, F; Miyamoto, M; Marneffe, A; Jemec, G B E; Del Marmol, V; Nebosis, R

2016-01-01

One of the most challenging problems in clinical dermatology is the early detection of melanoma. Reflectance confocal microscopy (RCM) is an added tool to dermoscopy improving considerably diagnostic accuracy. However, diagnosis strongly depends on the experience of physicians. High-definition optical coherence tomography (HD-OCT) appears to offer additional structural and cellular information on melanocytic lesions complementary to that of RCM. However, the diagnostic potential of HD-OCT seems to be not high enough for ruling out the diagnosis of melanoma if based on morphology analysis. The aim of this paper is first to quantify in vivo optical properties such as light attenuation in melanocytic lesions by HD-OCT. The second objective is to determine the best critical value of these optical properties for melanoma diagnosis. The technique of semi-log plot whereby an exponential function becomes a straight line has been implemented on HD-OCT signals coming from four successive skin layers (epidermis, upper papillary dermis, deeper papillary dermis and superficial reticular dermis). This permitted the HD-OCT in vivo measurement of skin entrance signal (SES), relative attenuation factor normalized for the skin entrance signal (µ raf1) and half value layer (z 1/2). The diagnostic accuracy of HD-OCT for melanoma detection based on the optical properties, µ raf1 , SES and z 1/2 was high (95.6, 82.2 and 88.9 %, respectively). High negative predictive values could be found for these optical properties (96.7, 89.3 and 96.3 %, respectively) compared to morphologic assessment alone (89.9 %), reducing the risk of mistreating a malignant lesion to a more acceptable level (3.3 % instead of 11.1 %). HD-OCT seems to enable the combination of in vivo morphological analysis of cellular and 3-D micro-architectural structures with in vivo analysis of optical properties of tissue scatterers in melanocytic lesions. In vivo HD-OCT analysis of optical properties permits melanoma diagnosis with higher accuracy than in vivo HD-OCT analysis of morphology alone.

Large area fabrication of plasmonic nanoparticle grating structure by conventional scanning electron microscope

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sudheer,, E-mail: sudheer@rrcat.gov.in; Tiwari, P.; Rai, V. N.

Plasmonic nanoparticle grating (PNG) structure of different periods has been fabricated by electron beam lithography using silver halide based transmission electron microscope film as a substrate. Conventional scanning electron microscope is used as a fabrication tool for electron beam lithography. Optical microscope and energy dispersive spectroscopy (EDS) have been used for its morphological and elemental characterization. Optical characterization is performed by UV-Vis absorption spectroscopic technique.

Morphology, structure and optical properties of hydrothermally synthesized CeO2/CdS nanocomposites

NASA Astrophysics Data System (ADS)

Mohanty, Biswajyoti; Nayak, J.

2018-04-01

CeO2/CdS nanocomposites were synthesized using a two-step hydrothermal technique. The effects of precursor concentration on the optical and structural properties of the CeO2/CdS nanoparticles were systematically studied. The morphology, composition and the structure of the CeO2/CdS nanocomposite powder were studied by scanning electron microscopy (SEM), energy dispersive X-ray spectrum analysis (EDXA) and X-ray diffraction (XRD), respectively. The optical properties of CeO2/CdS nanocomposites were studied by UV-vis absorption and photoluminescence (PL) spectroscopy. The optical band gaps of the CeO2/CdS nanopowders ranged from 2.34 eV to 2.39 eV as estimated from the UV-vis absorption. In the room temperature photoluminescence spectrum of CeO2/CdS nanopowder, a strong blue emission band was observed at 400 nm. Since the powder shows strong visible luminescence, it may be used as a blue phosphor in future. The original article published with this DOI was submitted in error. The correct article was inadvertently left out of the original submission. This has been rectified and the correct article was published online on 16 April 2018.

Rare earth substitution on structural and optical behaviour of CdSe thin films

NASA Astrophysics Data System (ADS)

Singh, Sarika; Shrivastava, A. K.; Tapdiya, Swati

2018-05-01

A series of Sm2+,Gd2+ doped with Cadmium selenide CdSe (x =0.01) has been prepared by using Chemical bath deposition technique. Structural, Optical and Morphological studies were performed using X-ray diffraction (XRD), UV-Visible spectrometer, Raman Studies and Scanning Electron Microscopy (SEM). XRD patterns confirm the samples with Sm,Gd ions, some diffraction peaks appeared which belongs to the cubic phase structure. The values of lattice parameter (a) decreased and particle size decrease on doping. Morphology of the grown films reveals that surface are homogeneous and uniformly spread on the substrates. The elemental analysis of CdSe doped Sm and Gd (1%) different composition was analyzed by Energy Dispersive X-Rays (EDX). The optical values of some important parameters of the studied films were calculated by UVstudy are determined from transmission spectra at wavelength 200 to 900nm. Optical band gap Eg was calculated by tauc relation. Energy band gap of CdSe doped with Sm and Gd varies at 1.8eV and 1.9eV respectively. Bandgap In Raman analysis, a prominent peak shows that confirmation of nano crystalline phase. And intensity of peaks was decreasing after doping.

Structural and optical properties of nano-structured CdS thin films prepared by chemical bath deposition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bai, Rekha, E-mail: rekha.mittal07@gmail.com; Kumar, Dinesh; Chaudhary, Sujeet

2016-05-06

Cadmium sulfide (CdS) thin films have been deposited on conducting glass substrates by chemical bath deposition (CBD) technique. The effect of precursor concentration on the structural, morphological, compositional, and optical properties of the CdS films has been studied. Crystal structure of these CdS films is characterized by X-ray diffraction (XRD) and it reveals polycrystalline structure with mixture of cubic and wurtzite phases with grain size decreasing as precursor concentration is increased. Optical studies reveal that the CdS thin films have high transmittance in visible spectral region reaching 90% and the films possess direct optical band gap that decreases from 2.46more » to 2.39 eV with decreasing bath concentration. Our study suggests that growth is nucleation controlled.« less

Structural, morphological and optical properties of pulsed laser deposited ZnSe/ZnSeO3 thin films

NASA Astrophysics Data System (ADS)

Hassan, Syed Ali; Bashir, Shazia; Zehra, Khushboo; Salman Ahmed, Qazi

2018-04-01

The effect of varying laser pulses on structural, morphological and optical behavior of Pulsed Laser Deposited (PLD) ZnSe/ZnSeO3 thin films has been investigated. The films were grown by employing Excimer laser (100 mJ, 248 nm, 18 ns, 30 Hz) at various number of laser pulses i.e. 3000, 4000, 5000 and 6000 with elevated substrate temperature of 300 °C. One film was grown at Room Temperature (RT) by employing 3000 number of laser pulses. In order to investigate the structural analysis of deposited films, XRD analysis was performed. It was observed that the room temperature is not favorable for the growth of crystalline film. However, elevated substrate temperature to 300°C, two phases with preferred orientation of ZnSeO3 (2 1 2) and ZnSe (3 3 1) were identified. AFM and SEM analysis were performed to explore the surface morphology of grown films. Morphological analysis also confirmed the non-uniform film growth at room temperature. At elevated substrate temperature (300 °C), the growth of dendritic rods and cubical crystalline structures are observed for lower number of laser pulses i.e. 3000 and 4000 respectively. With increased number of pulses i.e. 5000 and 6000, the films surface morphology becomes smooth which is confirmed by measurement of surface RMS roughness. Number of grains, skewness, kurtosis and other parameters have been evaluated by statistical analysis. In order to investigate the thickness, and optical properties of deposited films, ellipsometery and UV–Vis spectroscopy techniques were employed. The estimated band gap energy is 2.67 eV for the film grown at RT, whereas band gap values varies from 2.80 eV to 3.01 eV for the films grown at 300 °C with increasing number of laser pulses.

Morphology of diesel soot residuals from supercooled water droplets and ice crystals: Implications for optical properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

China, Swarup; Kulkarni, Gourihar; Scarnato, Barbara V.

Freshly emitted soot particles are fractal-like aggregates, but atmospheric processing often transforms their morphology. Morphology of soot particles plays an important role in determining their optical properties, life cycle and hence their effect on Earth’s radiative balance. However, little is known about the morphology of soot particles that participated in cold cloud processes. Here we report results from laboratory experiments that simulate cold cloud processing of diesel soot particles by allowing them to form supercooled droplets and ice crystals at -20 and -40°C, respectively. Electron microscopy revealed that soot residuals from ice crystals were more compact (roundness~0.55) than those frommore » supercooled droplets (roundness ~0.45), while nascent soot particles were the least compact (roundness~0.41). Optical simulations using the discrete dipole approximation showed that the more compact structure enhances soot single scattering albedo by a factor up to 1.4, thereby reducing the top-of-the-atmosphere direct radiative forcing by ~63%. Lastly, these results underscore that climate models should consider the morphological evolution of soot particles due to cold cloud processing to improve the estimate of direct radiative forcing of soot.« less

Morphology of diesel soot residuals from supercooled water droplets and ice crystals: Implications for optical properties

DOE PAGES

China, Swarup; Kulkarni, Gourihar; Scarnato, Barbara V.; ...

2015-11-01

Freshly emitted soot particles are fractal-like aggregates, but atmospheric processing often transforms their morphology. Morphology of soot particles plays an important role in determining their optical properties, life cycle and hence their effect on Earth’s radiative balance. However, little is known about the morphology of soot particles that participated in cold cloud processes. Here we report results from laboratory experiments that simulate cold cloud processing of diesel soot particles by allowing them to form supercooled droplets and ice crystals at -20 and -40°C, respectively. Electron microscopy revealed that soot residuals from ice crystals were more compact (roundness~0.55) than those frommore » supercooled droplets (roundness ~0.45), while nascent soot particles were the least compact (roundness~0.41). Optical simulations using the discrete dipole approximation showed that the more compact structure enhances soot single scattering albedo by a factor up to 1.4, thereby reducing the top-of-the-atmosphere direct radiative forcing by ~63%. Lastly, these results underscore that climate models should consider the morphological evolution of soot particles due to cold cloud processing to improve the estimate of direct radiative forcing of soot.« less

Impact of nucleation of carbonaceous clusters on structural, electrical and optical properties of Cr+-implanted PMMA

NASA Astrophysics Data System (ADS)

Arif, Shafaq; Rafique, M. Shahid; Saleemi, Farhat; Naab, Fabian; Toader, Ovidiu; Mahmood, Arshad; Aziz, Uzma

2016-09-01

Specimens of polymethylmethacrylate (PMMA) have been implanted with 400 keV Cr+ ions at different ion fluences ranging from 5 × 1013 to 5 × 1015 ions/cm2. The possible chemical reactions involved in the nucleation of conjugated carbonaceous clusters in implanted PMMA are discussed. Furthermore, impact of formation of carbonaceous clusters on structural, optical, electrical and morphological properties of implanted PMMA has been examined. The structural modifications in implanted PMMA are observed by Raman spectroscopy. The variation in optical band gap and Urbach energy is measured using UV-visible spectroscopic analysis. The effects of Cr+ ion implantation on electrical and morphological properties are investigated by four-probe apparatus and atomic force microscopy, respectively. The Raman spectroscopic analysis confirmed the formation of carbonaceous clusters with the transformation of implanted layer of PMMA into amorphous carbon. Simultaneously, the optical band gap of implanted PMMA has reduced from 3.13 to 0.85 eV. The increase in Urbach energy favors the decline in band gap together with the structural modification in implanted PMMA. As a result of Cr+ ion implantation, the electrical conductivity of PMMA has improved from 2.14 ± 0.06 × 10-10 S/cm (pristine) to 7.20 ± 0.36 × 10-6 S/cm. The AFM images revealed a decrease in surface roughness with an increment in ion fluence up to 5 × 1014 ions/cm2. The modification in the electrical, optical and structural properties makes the PMMA a promising candidate for its future utilization, as a semiconducting and optically active material, in various fields like plastic electronics and optoelectronic devices.

Structure, Morphology, and Optical Properties of Amorphous and Nanocrystalline Gallium Oxide Thin Films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kumar, S. Sampath; Rubio, E. J.; Noor-A-Alam, M.

Ga2O3 thin films were produced by sputter deposition by varying the substrate temperature (Ts) in a wide range (Ts=25-800 oC). The structural characteristics and optical properties of Ga2O3 films were evaluated using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry (EDS), Rutherford backscattering spectrometry (RBS) and spectrophotometric measurements. The effect of growth temperature is significant on the chemistry, crystal structure and morphology of Ga2O3 films. XRD and SEM analyses indicate that the Ga2O3 films grown at lower temperatures were amorphous while those grown at Ts≥500 oC were nanocrystalline. RBS measurements indicate the well-maintained stoichiometry of Ga2O3 films atmore » Ts=300-700 oC. The spectral transmission of the films increased with increasing temperature. The band gap of the films varied from 4.96 eV to 5.17 eV for a variation in Ts in the range 25-800 oC. A relationship between microstructure and optical property is discussed.« less

Structural and Luminescence Properties of Lu2O3:Eu3+ F127 Tri-Block Copolymer Modified Thin Films Prepared by Sol-Gel Method

PubMed Central

de Jesus Morales Ramírez, Angel; Hernández, Margarita García; Murillo, Antonieta García; de Jesús Carrillo Romo, Felipe; Palmerin, Joel Moreno; Velazquez, Dulce Yolotzin Medina; Jota, María Luz Carrera

2013-01-01

Lu2O3:Eu3+ transparent, high density, and optical quality thin films were prepared using the sol-gel dip-coating technique, starting with lutetium and europium nitrates as precursors and followed by hydrolysis in an ethanol-ethylene glycol solution. Acetic acid and acetylacetonate were incorporated in order to adjust pH and as a sol stabilizer. In order to increment the thickness of the films and orient the structure, F127 Pluronic acid was incorporated during the sol formation. Structural, morphological, and optical properties of the films were investigated for different F127/Lu molar ratios (0–5) in order to obtain high optical quality films with enhanced thickness compared with the traditional method. X-ray diffraction (XRD) shows that the films present a highly oriented cubic structure <111> beyond 1073 K for a 3-layer film, on silica glass substrates. The thickness, density, porosity, and refractive index evolution of the films were investigated by means of m-lines microscopy along with the morphology by scanning electron microscope (SEM) and luminescent properties. PMID:28809336

Investigation of nuclear nano-morphology marker as a biomarker for cancer risk assessment using a mouse model

NASA Astrophysics Data System (ADS)

Bista, Rajan K.; Uttam, Shikhar; Hartman, Douglas J.; Qiu, Wei; Yu, Jian; Zhang, Lin; Brand, Randall E.; Liu, Yang

2012-06-01

The development of accurate and clinically applicable tools to assess cancer risk is essential to define candidates to undergo screening for early-stage cancers at a curable stage or provide a novel method to monitor chemoprevention treatments. With the use of our recently developed optical technology--spatial-domain low-coherence quantitative phase microscopy (SL-QPM), we have derived a novel optical biomarker characterized by structure-derived optical path length (OPL) properties from the cell nucleus on the standard histology and cytology specimens, which quantifies the nano-structural alterations within the cell nucleus at the nanoscale sensitivity, referred to as nano-morphology marker. The aim of this study is to evaluate the feasibility of the nuclear nano-morphology marker from histologically normal cells, extracted directly from the standard histology specimens, to detect early-stage carcinogenesis, assess cancer risk, and monitor the effect of chemopreventive treatment. We used a well-established mouse model of spontaneous carcinogenesis--ApcMin mice, which develop multiple intestinal adenomas (Min) due to a germline mutation in the adenomatous polyposis coli (Apc) gene. We found that the nuclear nano-morphology marker quantified by OPL detects the development of carcinogenesis from histologically normal intestinal epithelial cells, even at an early pre-adenomatous stage (six weeks). It also exhibits a good temporal correlation with the small intestine that parallels the development of carcinogenesis and cancer risk. To further assess its ability to monitor the efficacy of chemopreventive agents, we used an established chemopreventive agent, sulindac. The nuclear nano-morphology marker is reversed toward normal after a prolonged treatment. Therefore, our proof-of-concept study establishes the feasibility of the SL-QPM derived nuclear nano-morphology marker OPL as a promising, simple and clinically applicable biomarker for cancer risk assessment and evaluation of chemopreventive treatment.

Structural, morphological, and optical properties of tin(IV) oxide nanoparticles synthesized using Camellia sinensis extract: a green approach

NASA Astrophysics Data System (ADS)

Selvakumari, J. Celina; Ahila, M.; Malligavathy, M.; Padiyan, D. Pathinettam

2017-09-01

Tin oxide (SnO2) nanoparticles were cost-effectively synthesized using nontoxic chemicals and green tea ( Camellia sinensis) extract via a green synthesis method. The structural properties of the obtained nanoparticles were studied using X-ray diffraction, which indicated that the crystallite size was less than 20 nm. The particle size and morphology of the nanoparticles were analyzed using scanning electron microscopy and transmission electron microscopy. The morphological analysis revealed agglomerated spherical nanoparticles with sizes varying from 5 to 30 nm. The optical properties of the nanoparticles' band gap were characterized using diffuse reflectance spectroscopy. The band gap was found to decrease with increasing annealing temperature. The O vacancy defects were analyzed using photoluminescence spectroscopy. The increase in the crystallite size, decreasing band gap, and the increasing intensities of the UV and visible emission peaks indicated that the green-synthesized SnO2 may play future important roles in catalysis and optoelectronic devices.

Morphological analysis of the growth stages of in-vivo mouse hair follicles by using optical coherence tomography

NASA Astrophysics Data System (ADS)

Jha, Rakesh Kumar; Kim, Kanghae; Jeon, Mansik; Kim, Jeehyun; Kang, Minyoung; Han, Insook; Kim, Moonkyu

2016-09-01

Swept-source optical coherence tomography (SS-OCT), a bio-photonic imaging modality, was used to demonstrate an initial feasibility experiment for detecting morphological variations of in-vivo mouse hair follicles for the anagen and the telogen growth stages. Two C57BL/6 adult male mice, one undergoing the anagen stage and the other undergoing the telogen stage of the hair follicle growth cycle, were selected for the experiment. The OCT cross-sectional images of mice skin were acquired in-vivo within an interval of 15 days, and the observed morphological changes were analyzed. The micro-structural features of mice skin on the 15th experimental day were further compared with corresponding histological observations. The preliminary result of this study provides clear insights into the structural details of mouse skin, confirming the resemblance of the OCT images with the corresponding histological measurements, and ensures the suitability of SS-OCT for non-invasive analysis of hair follicle conditions.

Effect of copper doping on the photocatalytic activity of ZnO thin films prepared by sol-gel method

NASA Astrophysics Data System (ADS)

Saidani, T.; Zaabat, M.; Aida, M. S.; Boudine, B.

2015-12-01

In the present work, we prepared undoped and copper doped ZnO thin films by the sol-gel dip coating method on glass substrates from zinc acetate dissolved in a solution of ethanol. The objective of our work is to study the effect of Cu doping with different concentrations on structural, morphological, optical properties and photocatalytic activity of ZnO thin films. For this purpose, we have used XRD to study the structural properties, and AFM to determine the morphology of the surface of the ZnO thin films. The optical properties and the photocatalytic degradation of the films were examined by UV-visibles spectrophotometer. The Tauc method was used to estimate the optical band gap. The XRD spectra indicated that the films have an hexagonal wurtzite structure, which gradually deteriorated with increasing Cu concentration. The results showed that the incorporation of Cu decreases the crystallite size. The AFM study showed that an increase of the concentration of Cu causes the decrease of the surface roughness, which passes from 20.2 for Un-doped ZnO to 12.16 nm for doped ZnO 5 wt% Cu. Optical measurements have shown that all the deposited films show good optical transmittance (77%-92%) in the visible region and increases the optical gap with increasing Cu concentration. The presence of copper from 1% to 5 wt% in the ZnO thin films is found to decelerate the photocatalytic process.

Structure, morphology and Raman and optical spectroscopic analysis of In1-xCuxP thin films grown by MOCVD technique for solar cell applications

NASA Astrophysics Data System (ADS)

Alshahrie, Ahmed; Juodkazis, S.; Al-Ghamdi, A. A.; Hafez, M.; Bronstein, L. M.

2017-10-01

Nanocrystalline In1-xCuxP thin films (0 ≤ x ≤ 0.5) have been deposited on quartz substrates by a Metal-Organic Chemical Vapor Deposition (MOCVD) technique. The effect of the copper ion content on the structural crystal lattice, morphology and optical behavior of the InP thin films was assessed using X-ray diffraction, scanning electron microscopy, atomic force microscopy, Raman spectroscopy and spectrophotometry. All films exhibited a crystalline cubic zinc blende structure, inferring the solubility of the Cu atoms in the InP crystal structure. The XRD patterns demonstrated that the inclusion of Cu atoms into the InP films forced the nanoparticles in the films to grow along the (1 1 1) direction. The AFM topography showed that the Cu ions reduce the surface roughness of deposited films. The Raman spectra of the deposited films contain the first and second order anti-stoke ΓTO, ΓLO, ΧLO + ΧTO, 2ΓTO, and ΓLO + ΓTO bands which are characteristic of the InP crystalline structure. The intensities of these bands decreased with increasing the content of the Cu atoms in the InP crystals implying the creation of a stacking fault density in the InP crystal structure. The In1-xCuxP thin films have shown high optical transparency of 90%. An increase of the optical band gap from 1.38 eV to 1.6 eV was assigned to the increase of the amount of Cu ions in the InP films. The In0.5Cu0.5P thin film exhibited remarkable optical conductivity with very low dissipation factor which makes it a promising buffer window for solar energy applications.

Habit modification of potassium acid phthalate (KAP) single crystals by impurities

NASA Astrophysics Data System (ADS)

Murugakoothan, P.; Mohan Kumar, R.; Ushasree, P. M.; Jayavel, R.; Dhanasekaran, R.; Ramasamy, P.

1999-12-01

Nonlinear optical materials potassium dihydrogen phosphate (KDP), urea and L-arginine phosphate (LAP)-doped KAP crystals were grown by the slow cooling method. The LAP-doped crystals show pronounced habit modification compared to KDP and urea doping. The effect of these impurities on growth kinetics, surface morphology, habit modification, structure, optical and mechanical properties have been studied. Among the three impurities, urea doping yields high mechanical stability and optical transmission and for KDP and LAP doping there is a decrease in optical transmission.

Revealing retroperitoneal liposarcoma morphology using optical coherence tomography

NASA Astrophysics Data System (ADS)

Carbajal, Esteban F.; Baranov, Stepan A.; Manne, Venu G. R.; Young, Eric D.; Lazar, Alexander J.; Lev, Dina C.; Pollock, Raphael E.; Larin, Kirill V.

2011-02-01

A new approach to distinguish normal fat, well-differentiated (WD), and dedifferentiated liposarcoma (LS) tumors is demonstrated, based on the use of optical coherence tomography (OCT). OCT images show the same structures seen with conventional histological methods. Our visual grading analysis is supported by numerical analysis of observed structures for normal fat and WDLS samples. Further development could apply the real-time and high resolution advantages of OCT for use in liposarcoma diagnosis and clinical procedures.

Linking Precursor Alterations to Nanoscale Structure and Optical Transparency in Polymer Assisted Fast-Rate Dip-Coating of Vanadium Oxide Thin Films

PubMed Central

Glynn, Colm; Creedon, Donal; Geaney, Hugh; Armstrong, Eileen; Collins, Timothy; Morris, Michael A.; Dwyer, Colm O’

2015-01-01

Solution processed metal oxide thin films are important for modern optoelectronic devices ranging from thin film transistors to photovoltaics and for functional optical coatings. Solution processed techniques such as dip-coating, allow thin films to be rapidly deposited over a large range of surfaces including curved, flexible or plastic substrates without extensive processing of comparative vapour or physical deposition methods. To increase the effectiveness and versatility of dip-coated thin films, alterations to commonly used precursors can be made that facilitate controlled thin film deposition. The effects of polymer assisted deposition and changes in solvent-alkoxide dilution on the morphology, structure, optoelectronic properties and crystallinity of vanadium pentoxide thin films was studied using a dip-coating method using a substrate withdrawal speed within the fast-rate draining regime. The formation of sub-100 nm thin films could be achieved rapidly from dilute alkoxide based precursor solutions with high optical transmission in the visible, linked to the phase and film structure. The effects of the polymer addition was shown to change the crystallized vanadium pentoxide thin films from a granular surface structure to a polycrystalline structure composed of a high density of smaller in-plane grains, resulting in a uniform surface morphology with lower thickness and roughness. PMID:26123117

Investigations on structural, vibrational, morphological and optical properties of CdS and CdS/Co films by ultrasonic spray pyrolysis

NASA Astrophysics Data System (ADS)

Aksay, S.; Polat, M.; Özer, T.; Köse, S.; Gürbüz, G.

2011-09-01

CdS and CdS/Co films have been deposited on glass substrates by an ultrasonic spray pyrolysis method. The effects of Co incorporation on the structural, optical, morphological, elemental and vibrational properties of these films were investigated. XRD analysis confirmed the hexagonal wurtzite structure of all films and had no impurity phase. While CdS film has (0 0 2) as the preferred orientation, CdS/Co films have (1 1 0) as the preferred orientation. The direct optical band gap was found to decrease from 2.42 to 2.39 eV by Co incorporation. The decrease of the direct energy gaps by increasing Co contents is mainly due to the sp-d exchange interaction between the localized d-electrons of Co2+ ions and band electrons of CdS. After the optical investigations, it was seen that the transmittance of CdS films decreased by Co content. The Raman measurements revealed two peaks corresponding to the 1LO and 2LO modes of hexagonal CdS. The vibrational modes of Cd-S were obtained in the wavenumber range (590-715 cm-1) using Fourier transform infrared spectroscopy (FTIR). The elemental analysis of the film was done by energy dispersive X-ray spectrometry.

Facile growth of barium oxide nanorods: structural and optical properties.

PubMed

Ahmad, Naushad; Wahab, Rizwan; Alam, Manawwer

2014-07-01

This paper reports a large-scale synthesis of barium oxide nanorods (BaO-NRs) by simple solution method at a very low-temperature of - 60 degrees C. The as-grown BaO-NRs were characterized in terms of their morphological, structural, compositional, optical and thermal properties. The morphological characterizations of as-synthesized nanorods were done by scanning electron microscopy (SEM) which confirmed that the synthesized products are rod shaped and grown in high density. The nanorods exhibits smooth and clean surfaces throughout their lengths. The crystalline property of the material was analyzed with X-ray diffraction pattern (XRD). The compositional and thermal properties of synthesized nanorods were observed via Fourier transform infrared (FTIR) spectroscopy and thermogravimetric analysis which confirmed that the synthesized nanorods are pure BaO and showed good thermal stability. The nanorods exhibited good optical properties as was confirmed from the room-temperature UV-vis spectroscopy. Finally, a plausible mechanism for the formation of BaO-NRs is also discussed in this paper.

Rapid Production of Internally Structured Colloids by Flash Nanoprecipitation of Block Copolymer Blends.

PubMed

Grundy, Lorena S; Lee, Victoria E; Li, Nannan; Sosa, Chris; Mulhearn, William D; Liu, Rui; Register, Richard A; Nikoubashman, Arash; Prud'homme, Robert K; Panagiotopoulos, Athanassios Z; Priestley, Rodney D

2018-05-08

Colloids with internally structured geometries have shown great promise in applications ranging from biosensors to optics to drug delivery, where the internal particle structure is paramount to performance. The growing demand for such nanomaterials necessitates the development of a scalable processing platform for their production. Flash nanoprecipitation (FNP), a rapid and inherently scalable colloid precipitation technology, is used to prepare internally structured colloids from blends of block copolymers and homopolymers. As revealed by a combination of experiments and simulations, colloids prepared from different molecular weight diblock copolymers adopt either an ordered lamellar morphology consisting of concentric shells or a disordered lamellar morphology when chain dynamics are sufficiently slow to prevent defect annealing during solvent exchange. Blends of homopolymer and block copolymer in the feed stream generate more complex internally structured colloids, such as those with hierarchically structured Janus and patchy morphologies, due to additional phase separation and kinetic trapping effects. The ability of the FNP process to generate such a wide range of morphologies using a simple and scalable setup provides a pathway to manufacturing internally structured colloids on an industrial scale.

Structure of first- and second-stage mineralized elements in teeth of the sea urchin Lytechinus variegatus.

PubMed

Robach, J S; Stock, S R; Veis, A

2009-12-01

Microstructure of the teeth of the sea urchin Lytechinus variegatus was investigated using optical microscopy, SEM (scanning electron microscopy) and SIMS (secondary ion mass spectroscopy). The study focused on the internal structure of the first-stage mineral structures of high Mg calcite (primary, secondary and carinar process plates, prisms) and on morphology of the columns of second-stage mineral (very high Mg calcite) that cement the first-stage material together. Optical micrographs under polarized light revealed contrast in the centers (midlines) of carinar process plates and in prisms in polished sections; staining of primary and carinar process plates revealed significant dye uptake at the plate centers. Demineralization with and without fixation revealed that the midlines of primary and carinar process plates (but not secondary plates) and the centers of prisms differed from the rest of the plate or prism, and SIMS showed proteins concentrated in these plate centers. SEM was used to study the morphology of columns, the fracture surfaces of mature teeth and the 3D morphology of prisms. These observations of internal structures in plates and prisms offer new insight into the mineralization process and suggest an important role for protein inclusions within the first-stage mineral. Some of the 3D structures not reported previously, such as twisted prisms and stacks of carinar process plates with nested wrinkles, may represent structural strengthening strategies.

Surface morphological, structural, electrical and optical properties of GaN-based light-emitting diodes using submicron-scaled Ag islands and ITO thin films

NASA Astrophysics Data System (ADS)

Lee, Young-Woong; Reddy, M. Siva Pratap; Kim, Bo-Myung; Park, Chinho

2018-07-01

An ITO-Ag islands complex as a new transparent conducting electrode (TCE) structure (on the 5 nm-thick p-InGaN/90 nm-thick p-GaN) for achieving high-performance and more reliable GaN-based LEDs were fabricated. A normal LED with a conventional ITO TCE was also compared. The surface morphological, structural, electrical and optical properties of fabricated GaN-based light-emitting diodes using a complex electrode of submicron-scaled Ag islands and ITO thin films are explored by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), current-voltage (I-V) and output power-current (L-I) techniques. Surface morphology investigations revealed Ag islands formed uniformly on the p-InGaN/p-GaN surface during rapid thermal annealing at 400 °C for 1 min in N2 ambient. The ohmic properties and overall device-performance of the suggested contact and device structures were superior to those in the conventional ITO contact and normal ITO LED structures. Based on the results of XRD and XPS measurements, the formation of the intermetallic gallide phases (AgGa) is responsible for better performance characteristics of the ITO-Ag islands device. The significant improvements are described in terms of the conducting bridge influence, highly effective micro-mirror effect, and wider photon window via the roughened structure.

Structure of first- and second-stage mineralized elements in teeth of the sea urchin Lytechinus variegatus

PubMed Central

Robach, J. S.; Stock, S. R.; Veis, A.

2009-01-01

Microstructure of the teeth of the sea urchin Lytechinus variegatus was investigated using optical microscopy, SEM (scanning electron microscopy) and SIMS (secondary ion mass spectroscopy). The study focused on the internal structure of the first-stage mineral structures of high Mg calcite (primary, secondary and carinar process plates; prisms) and on morphology of the columns of second-stage mineral (very high Mg calcite) that cement the first-stage material together. Optical micrographs under polarized light revealed contrast in the centers (midlines) of carinar process plates and in prisms in polished sections; staining of primary and carinar process plates revealed significant dye uptake at the plate centers. Demineralization with and without fixation revealed that the midlines of primary and carinar process plates (but not secondary plates) and the centers of prisms differed from the rest of the plate or prism, and SIMS showed proteins concentrated in these plate centers. SEM was used to study the morphology of columns, the fracture surfaces of mature teeth and the 3D morphology of prisms. These observations of internal structures in plates and prisms offer new insight into the mineralization process and suggest an important role for protein inclusions within the first-stage mineral. Some of the 3D structures not reported previously, such as twisted prisms and stacks of carinar process plates with nested wrinkles, may represent structural strengthening strategies. PMID:19616101

Programmable Bidirectional Folding of Metallic Thin Films for 3D Chiral Optical Antennas.

PubMed

Mao, Yifei; Zheng, Yun; Li, Can; Guo, Lin; Pan, Yini; Zhu, Rui; Xu, Jun; Zhang, Weihua; Wu, Wengang

2017-05-01

3D structures with characteristic lengths ranging from nanometer to micrometer scale often exhibit extraordinary optical properties, and have been becoming an extensively explored field for building new generation nanophotonic devices. Albeit a few methods have been developed for fabricating 3D optical structures, constructing 3D structures with nanometer accuracy, diversified materials, and perfect morphology is an extremely challenging task. This study presents a general 3D nanofabrication technique, the focused ion beam stress induced deformation process, which allows a programmable and accurate bidirectional folding (-70°-+90°) of various metal and dielectric thin films. Using this method, 3D helical optical antennas with different handedness, improved surface smoothness, and tunable geometries are fabricated, and the strong optical rotation effects of single helical antennas are demonstrated. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Comparative study on structural and optical properties of CdS films fabricated by three different low-cost techniques

NASA Astrophysics Data System (ADS)

Ravichandran, K.; Philominathan, P.

2009-03-01

Highly crystalline and transparent cadmium sulphide films were fabricated at relatively low temperature by employing an inexpensive, simplified spray technique using perfume atomizer (generally used for cosmetics). The structural, surface morphological and optical properties of the films were studied and compared with that prepared by conventional spray pyrolysis using air as carrier gas and chemical bath deposition. The films deposited by the simplified spray have preferred orientation along (1 0 1) plane. The lattice parameters were calculated as a = 4.138 Å and c = 6.718 Å which are well agreed with that obtained from the other two techniques and also with the standard data. The optical transmittance in the visible range and the optical band gap were found as 85% and 2.43 eV, respectively. The structural and optical properties of the films fabricated by the simplified spray are found to be desirable for opto-electronic applications.

Complex and oriented ZnO nanostructures.

PubMed

Tian, Zhengrong R; Voigt, James A; Liu, Jun; McKenzie, Bonnie; McDermott, Matthew J; Rodriguez, Mark A; Konishi, Hiromi; Xu, Huifang

2003-12-01

Extended and oriented nanostructures are desirable for many applications, but direct fabrication of complex nanostructures with controlled crystalline morphology, orientation and surface architectures remains a significant challenge. Here we report a low-temperature, environmentally benign, solution-based approach for the preparation of complex and oriented ZnO nanostructures, and the systematic modification of their crystal morphology. Using controlled seeded growth and citrate anions that selectively adsorb on ZnO basal planes as the structure-directing agent, we prepared large arrays of oriented ZnO nanorods with controlled aspect ratios, complex film morphologies made of oriented nanocolumns and nanoplates (remarkably similar to biomineral structures in red abalone shells) and complex bilayers showing in situ column-to-rod morphological transitions. The advantages of some of these ZnO structures for photocatalytic decompositions of volatile organic compounds were demonstrated. The novel ZnO nanostructures are expected to have great potential for sensing, catalysis, optical emission, piezoelectric transduction, and actuations.

Assessing embryo development using swept source optical coherence tomography

NASA Astrophysics Data System (ADS)

Caujolle, S.; Cernat, R.; Silvestri, G.; Marques, M. J.; Bradu, A.; Feuchter, T.; Robinson, G.; Griffin, D.; Podoleanu, A.

2018-03-01

A detailed assessment of embryo development would assist biologists with selecting the most suitable embryos for transfer leading to higher pregnancy rates. Currently, only low resolution microscopy is employed to perform this assessment. Although this method delivers some information on the embryo surface morphology, no specific details are shown related to its inner structure. Using a Master-Slave Swept-Source Optical Coherence Tomography (SS-OCT), images of bovine embryos from day 7 after fertilization were collected from different depths. The dynamic changes inside the embryos were examined, in detail and in real-time from several depths. To prove our ability to characterize the morphology, a single embryo was imaged over 26 hours. The embryo was deprived of its life support environment, leading to its death. Over this period, clear morphological changes were observed.

Morphologies and optical and electrical properties of InGaN/GaN micro-square array light-emitting diode chips.

PubMed

Han, Dan; Ma, Shufang; Jia, Zhigang; Liu, Peizhi; Jia, Wei; Shang, Lin; Zhai, Guangmei; Xu, Bingshe

2018-04-10

InGaN/GaN micro-square array light-emitting diode (LED) chips (micro-chips) have been prepared via the focused ion beam (FIB) etching technique, which can not only reduce ohmic contact degradation but also control the aspect ratio precisely in three-dimensional (3D) structure LED (3D-LED) device fabrication. The effects of FIB beam current and micro-square array depth on morphologies and optical and electrical properties of the micro-chips have been studied. Our results show that sidewall surface morphology and optical and electrical properties of the micro-chips degrade with increased beam current. After potassium hydroxide etching with different times, an optimal current-voltage and luminescence performance can be obtained. Combining the results of cathodoluminescence mappings and light output-current characteristics, the light extraction efficiency of the micro-chips is reduced as FIB etch depth increases. The mechanisms of micro-square depth on light extraction have been revealed by 3D finite difference time domain.

Morphological phenotyping of mouse hearts using optical coherence tomography

NASA Astrophysics Data System (ADS)

Cua, Michelle; Lin, Eric; Lee, Ling; Sheng, Xiaoye; Wong, Kevin S. K.; Tibbits, Glen F.; Beg, Mirza Faisal; Sarunic, Marinko V.

2014-11-01

Transgenic mouse models have been instrumental in the elucidation of the molecular mechanisms behind many genetically based cardiovascular diseases such as Marfan syndrome (MFS). However, the characterization of their cardiac morphology has been hampered by the small size of the mouse heart. In this report, we adapted optical coherence tomography (OCT) for imaging fixed adult mouse hearts, and applied tools from computational anatomy to perform morphometric analyses. The hearts were first optically cleared and imaged from multiple perspectives. The acquired volumes were then corrected for refractive distortions, and registered and stitched together to form a single, high-resolution OCT volume of the whole heart. From this volume, various structures such as the valves and myofibril bundles were visualized. The volumetric nature of our dataset also allowed parameters such as wall thickness, ventricular wall masses, and luminal volumes to be extracted. Finally, we applied the entire acquisition and processing pipeline in a preliminary study comparing the cardiac morphology of wild-type mice and a transgenic mouse model of MFS.

Solar-insolation-induced changes in the coma morphology of comet 67P/Churyumov-Gerasimenko. Optical monitoring with the Nordic Optical Telescope

NASA Astrophysics Data System (ADS)

Zaprudin, B.; Lehto, H. J.; Nilsson, K.; Somero, A.; Pursimo, T.; Snodgrass, C.; Schulz, R.

2017-07-01

Context. 67P/Churyumov-Gerasimenko (67P/C-G) is a short-period Jupiter family comet with an orbital period of 6.55 yr. Being the target comet of ESA's Rosetta mission, 67P/C-G has become one of the most intensively studied minor bodies of the solar system. The Rosetta Orbiter and the Philae Lander have brought us unique information about the structure and activity of the comet nucleus, as well as its activity along the orbit, composition of gas, and dust particles emitted into the coma. However, as Rosetta stayed in very close proximity to the cometary nucleus (less than 500 km with a few short excursions reaching up to 1500 km), it could not see the global picture of a coma at the scales reachable by telescopic observations (103 - 105 km). Aims: In this work we aim to connect in-situ observations made by Rosetta with the morphological evolution of the coma structures monitored by the ground-based observations. In particular, we concentrate on causal relationships between the coma morphology and evolution observed with the Nordic Optical Telescope (NOT) in the Canary Islands, and the seasonal changes of the insolation and the activity of the comet observed by the Rosetta instruments. Methods: Comet 67P/C-G was monitored with the NOT in imaging mode in two colors. Imaging optical observations were performed roughly on a weekly basis, which provides good coverage of short- and long-term variability. With the three dimensional modeling of the coma produced by active regions on the southern hemisphere, we aim to qualify the observed morphology by connecting it to the activity observed by Rosetta. Results: During our monitoring program, we detected major changes in the coma morphology of comet 67P/C-G. These were long-term and long-lasting changes. They do not represent any sudden outburst or short transient event, but are connected to seasonal changes of the surface insolation and the emergence of new active regions on the irregular shaped comet nucleus. We have also found significant deviations in morphological changes from the prediction models based on previous apparitions of 67P/C-G, like the time delay of the morphology changes and the reduced activity in the northern hemisphere. According to our modeling of coma structures and geometry of observations, the changes are clearly connected with the activity in the southern hemisphere observed by the Rosetta spacecraft.

The effect of gamma irradiation on chemical, morphology and optical properties of polystyrene nanosphere at various exposure time

NASA Astrophysics Data System (ADS)

Alhaji Yabagi, Jibrin; Isah Kimpa, Mohammed; Nmayaya Muhammad, Muhammad; Rashid, Saiful Bin; Zaidi, Embong; Arif Agam, Mohd

2018-01-01

Irradiation of polymers causes structural, chemical and the optical properties changes. Polystyrene nanosphere was drop coated to substrates and the gamma irradiation was carried out in a Cesium-137 (Cs-137) source chamber at different time (1-5 hours) with constant dose of 30 kGy. Fourier transformation infrared spectroscopy (FTIR) and Raman spectroscopy were employed to characterize the chemical properties of irradiated polystyrene while Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) were used to study the surface morphological changes of the samples. The optical energy band gaps of the thin films were investigated and studied using transmittance and absorbance measurements. The results obtained revealed that as irradiation time increases the optical properties changes and polystyrene gradually undergoes crystal to carbonaceous from its amorphous state. The average particles diameter and roughness of the samples decreases with increasing irradiation time.

Comparison between invasive and noninvasive techniques of evaluation of microvascular structural alterations.

PubMed

De Ciuceis, Carolina; Agabiti Rosei, Claudia; Caletti, Stefano; Trapletti, Valentina; Coschignano, Maria A; Tiberio, Guido A M; Duse, Sarah; Docchio, Franco; Pasinetti, Simone; Zambonardi, Federica; Semeraro, Francesco; Porteri, Enzo; Solaini, Leonardo; Sansoni, Giovanna; Pileri, Paola; Rossini, Claudia; Mittempergher, Francesco; Portolani, Nazario; Ministrini, Silvia; Agabiti-Rosei, Enrico; Rizzoni, Damiano

2018-05-01

The evaluation of the morphological characteristics of small resistance arteries in humans is challenging. The gold standard method is generally considered to be the measurement by wire or pressure micromyography of the media-to-lumen ratio of subcutaneous small vessels obtained by local biopsies. However, noninvasive techniques for the evaluation of retinal arterioles were recently proposed; in particular, two approaches, scanning laser Doppler flowmetry (SLDF) and adaptive optics, seem to provide useful information; both of them provide an estimation of the wall-to-lumen ratio (WLR) of retinal arterioles. Moreover, a noninvasive measurement of basal and total capillary density may be obtained by videomicroscopy/capillaroscopy. No direct comparison of these three noninvasive techniques in the same population was previously performed; in particular, adaptive optics was never validated against micromyography. In the current study, we enrolled 41 controls and patients: 12 normotensive lean controls, 12 essential hypertensive lean patients, nine normotensive obese patients and eight hypertensive obese patients undergoing elective surgery. All patients underwent a biopsy of subcutaneous fat during surgery. Subcutaneous small resistance artery structure was assessed by wire micromyography and the media-to-lumen ratio was calculated. WLR of retinal arterioles was obtained by SLDF and adaptive optics. Functional (basal) and structural (total) microvascular density was evaluated by capillaroscopy before and after venous congestion. Our data suggest that adaptive optics has a substantial advantage over SLDF in terms of evaluation of microvascular morphology, as WLR measured with adaptive optics is more closely correlated with the M/L of subcutaneous small arteries (r = 0.84, P < 0.001 vs. r = 0.52, P < 0.05, slopes of the relations: P < 0.01 adaptive optics vs. SLDF). In addition, the reproducibility of the evaluation of the WLR with adaptive optics is far better, as compared with SLDF, as intraobserver and interobserver variation coefficients are clearly smaller. This may be important in terms of clinical evaluation of microvascular morphology in a clinical setting, as micromyography has substantial limitations in its clinical application due to the local invasiveness of the procedure.

Surface morphology, optical, and electrochromic properties of nanostructured nickel ferrite (NiFe2O4) prepared by sol-gel method: effects of Ni/Fe molar ratios

NASA Astrophysics Data System (ADS)

Bazhan, Z.; Ghodsi, F. E.; Mazloom, J.

2016-05-01

Nanostructured nickel ferrite (NF) was prepared by the sol-gel method and calcined at 500 °C for 2 h. The effect of Ni/Fe molar ratios (0, 10, 30, 50 %) on structural, morphological, compositional, optical, and magnetic properties of samples was investigated using analytical tools. XRD patterns indicated the presence of hematite phase in the pure and 10 % NF samples. The samples of 30 and 50 % Ni/Fe molar ratios showed the formation of nickel ferrite structure. Using AFM images, power spectrum density analysis were performed for Ni/Fe with different molar ratio. Also the effect of thickness on morphology of 30 % sample was studied. The fractal dimension increases by increasing the Ni/Fe molar ratio. Optical parameters were evaluated by theoretical approach, and compositional dependence of these parameters was discussed comprehensively. Band gap narrowing was observed in nickel ferrite thin films by increasing the nickel contents from 10 to 50 %. Magnetic analysis revealed that increasing nickel content improved the saturation magnetization. Electrochemical measurements indicated that NF thin films have higher total charge density rather than Fe2O3 thin films and the ion storage capacitance of NF thin films increased by increasing the Ni/Fe content.

The effect of ultrasonic irradiation on the structure, morphology and photocatalytic performance of ZnO nanoparticles by sol-gel method.

PubMed

Mahdavi, Reza; Ashraf Talesh, S Siamak

2017-11-01

In this research, the effect of ultrasonic irradiation power (0, 75, 150 and 200W) and time (0, 5, 15 and 20min) on the structure, morphology and photocatalytic activity of zinc oxide nanoparticles synthesized by sol-gel method was investigated. Crystallographic structures and the morphologies of the resultant powders were determined by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The XRD patterns showed that ZnO samples were crystallized in their pure phase. The purity of samples was increased by increasing the ultrasonic irradiation power and time. Not only did ultrasonic irradiation unify both the structure and the morphology, but also it reduced the size and prohibited particles from aggregation. The optical behavior of the samples was studied by UV-vis spectroscopy. Photocatalytic activity of particles was measured by degradation of methyl orange under radiation of ultraviolet light. Ultrasound nanoparticles represented higher degradation compared to non-ultrasound ones. Copyright © 2017 Elsevier B.V. All rights reserved.

Structural, optical and magnetic studies of CuFe2O4, MgFe2O4 and ZnFe2O4 nanoparticles prepared by hydrothermal/solvothermal method

NASA Astrophysics Data System (ADS)

Kurian, Jessyamma; Mathew, M. Jacob

2018-04-01

In this paper we report the structural, optical and magnetic studies of three spinel ferrites namely CuFe2O4, MgFe2O4 and ZnFe2O4 prepared in an autoclave under the same physical conditions but with two different liquid medium and different surfactant. We use water as the medium and trisodium citrate as the surfactant for one method (Hydrothermal method) and ethylene glycol as the medium and poly ethylene glycol as the surfactant for the second method (solvothermal method). The phase identification and structural characterization are done using XRD and morphological studies are carried out by TEM. Cubical and porous spherical morphologies are obtained for hydrothermal and solvothermal process respectively without any impurity phase. The optical studies are carried out using FTIR and UV-Vis reflectance spectra. In order to elucidate the nonlinear optical behaviour of the prepared nanomaterial, open aperture z-scan technique is used. From the fitted z-scan curves nonlinear absorption coefficient and the saturation intensity are determined. The magnetic characterization of the samples is performed at room temperature using vibrating sample magnetometer measurements. The M-H curves obtained are fitted using theoretical equation and the different components of magnetization are determined. Nanoparticles with high saturation magnetization are obtained for MgFe2O4 and ZnFe2O4 prepared under solvothermal reaction. The magnetic hyperfine parameters and the cation distribution of the prepared materials are determined using room temperature Mössbauer spectroscopy. The fitted spectra reveal the difference in the magnetic hyperfine parameters owing to the change in size and morphology.

Revealing fine microstructural morphology in the living human retina using Optical Coherence Tomography with pancorrection

NASA Astrophysics Data System (ADS)

Torti, C.; Považay, B.; Hofer, B.; Unterhuber, A.; Hermann, B.; Drexler, W.

2008-09-01

Ultra-high speed optical coherence tomography employing an ultra-broadband light source has been combined with adaptive optics utilizing a single high stroke deformable mirror and chromatic aberration compensation. The reduction of motion artefacts, geometric and chromatic aberrations (pancorrection) permits to achieve an isotropic resolution of 2-3 μm in the human eye. The performance of this non-invasive imaging modality enables to resolve cellular structures including cone photoreceptors, nerve fibre bundles and collagenous plates of the lamina cribrosa, and retinal pigment epithelial (RPE) cells in the human retina in vivo with superior detail. Alterations of cellular morphology due to cone degeneration in a colour-blind subject are investigated in ultra-high resolution with selective depth sectioning for the first time.

Structural and optical properties of nanostructured CdSe thin films prepared by electrochemical deposition

NASA Astrophysics Data System (ADS)

Bai, Rekha; Chaudhary, Sujeet; Pandya, Dinesh K.

2018-05-01

Cadmium selenide (CdSe) nanostructured thin films have been grown on fluorine doped tin oxide (FTO) coated glass substrates by potentiostatic electrochemical deposition (ECD) technique for use in solar energy conversion devices. The effect of bath temperature on the structural, morphological and optical properties of prepared CdSe films has been explored. X-ray diffraction (XRD) and Raman spectroscopy clearly show that the CdSe films are polycrystalline and exhibit phase transformation from wurtzite to zincblende structure with increase in bath temperature. Optical spectra reveal that the nanostructured CdSe films have high absorbance in visible region and the films show a red shift in direct optical energy band gap from 1.90 to 1.65 eV with increase in bath temperature due to change in phase and bandgap tuning related to quantum confinement effect.

SILAR derived CdO films: Effect of triethanolamine on the surface morphology and optical bandgap energy

NASA Astrophysics Data System (ADS)

Sahin, B.; Aydin, R.

2018-07-01

Nanostructured CdO films have been successfully synthesized with different ratios of surfactant triethanolamine (TEA) under SILAR condition. The influence of addition of TEA on the physical properties of CdO nanoparticles was studied. The surface morphology of the films was studied by metallurgical microscope and SEM analysis. Surface topography of the film was studied by AFM. The structural properties of the samples were studied by X-ray diffraction (XRD). The XRD studies confirm that the deposited CdO films has cubic structure (111) preferred orientation with well-crystallinity and purity. The optical bandgap energy was estimated based on the UV-vis spectroscopies which were obtained in the range of 2.16 eV-2.46 eV. Our study is encouraging to get enhanced surface topography by surfactant TEA.

Simulation and Implementation of a Morphology-Tuned Gold Nano-Islands Integrated Plasmonic Sensor

PubMed Central

Ozhikandathil, Jayan; Packirisamy, Muthukumaran

2014-01-01

This work presents simulation, analysis and implementation of morphology tuning of gold nano-island structures deposited by a novel convective assembly technique. The gold nano-islands were simulated using 3D Finite-Difference Time-Domain (FDTD) techniques to investigate the effect of morphological changes and adsorption of protein layers on the localized surface plasmon resonance (LSPR) properties. Gold nano-island structures were deposited on glass substrates by a novel and low-cost convective assembly process. The structure formed by an uncontrolled deposition method resulted in a nano-cluster morphology, which was annealed at various temperatures to tune the optical absorbance properties by transforming the nano-clusters to a nano-island morphology by modifying the structural shape and interparticle separation distances. The dependence of the size and the interparticle separation distance of the nano-islands on the LSPR properties were analyzed in the simulation. The effect of adsorption of protein layer on the nano-island structures was simulated and a relation between the thickness and the refractive index of the protein layer on the LSPR peak was presented. Further, the sensitivity of the gold nano-island integrated sensor against refractive index was computed and compared with the experimental results. PMID:24932868

Structural, morphological, optical and electrical properties of Schottky diodes based on CBD deposited ZnO:Cu nanorods

NASA Astrophysics Data System (ADS)

Mwankemwa, Benard S.; Legodi, Matshisa J.; Mlambo, Mbuso; Nel, Jackie M.; Diale, Mmantsae

2017-07-01

Undoped and copper doped zinc oxide (ZnO) nanorods have been synthesized by a simple chemical bath deposition (CBD) method at a temperature of 90 °C. Structural, morphological, optical and electrical properties of the synthesized ZnO nanorods were found to be dependent on the Cu doping percentage. X-ray diffraction (XRD) patterns revealed strong diffraction peaks of hexagonal wurtzite of ZnO, and no impurity phases from metallic zinc or copper. Scanning electron microscopy (SEM) images showed changes in diameter and shape of nanorods, where by those doped with 2 at.% and 3 at.% aggregated and became compact. Selected area electron diffraction (SAED) patterns indicates high quality, single crystalline wurtzite structure ZnO and intensities of bright spots varied with copper doping concentration. UV-visible absorption peaks of ZnO red shifted with increasing copper doping concentration. Raman studies demonstrated among others, strong and sharp E2 (low) and E2 (high) optical phonon peaks confirming crystal structure of ZnO. Current-voltage measurements based on the gold/ZnO nanorods/ITO showed good rectifying behavior of the Schottky diode. The predicted Schottky barrier height of 0.60 eV was obtained which is not far from the theoretical Schottky-Mott value of 0.80 eV.

Structural and optical properties of co-precipitated copper doped zinc oxide

NASA Astrophysics Data System (ADS)

Pandey, Devendra K.; Modi, Anchit; Pandey, Padmini; Gaur, N. K.

2018-05-01

We have synthesized pure and copper doped zinc oxide Zn1-xO:Cux (x = 0, 0.03) powder by wet chemical co-precipitation method followed by sintering of the co-precipitated amorphous phase powder at 450°C for 4 hours. The experiment is performed to recognize the effect of nominal doping of transition metal over the structural, morphological and optical properties. The structural parameters are observed by using Rietveld refinement of X-ray diffraction data which clearly represents that Cu ion is perfectly incorporated at the Zn site with minimal distortions within the lattice. The crystallite size is estimated by Debye-Scherrer and Hall-Williamson formulation. The particle morphology and size is determined with scanning electron microscopic (SEM) technique. The band gap and optical measurements are carried out with UV-visible absorption and photoluminescence (PL) spectroscopic technique, respectively. Enhanced PL spectral response is observed for ZnO:Cu along with non-radiative transitions from conduction band to valence band. The energy levels near the conduction band that are commonly involved in the optoelectronic transitions in the UV-region are traced by using absorption and luminescence spectral graphs.

Morphological, structural and optical properties of MEH-PPV: PC70BM nanocomposite film

NASA Astrophysics Data System (ADS)

Mhamdi, Asya; Sweii, Fatma ben Slama; Saidi, Hamza; Saidi, Faouzi; Bouazizi, Abdelaziz

2018-05-01

In this report, the influence of annealing temperature and spin coating speed on the structural and morphological properties of a blend of poly (2-methoxy-5-(2-ethyl-oxy)-p-phenylene-vinylene) (MEH-PPV) and [6-6]-phenyl-C71-butyric acid methyl ester (PC70BM) layer has been investigated. The photoactive layer (MEH-PPV: PC70BM) was deposited on ZnO film deposited on top of indium tin oxide (ITO) substrate by spin-coating. The effect of spin coating speed via atomic force microscope (AFM) leads to conclude that high speed is favorable for a good homogeneity of the film surface and good aggregates dispersion. The optimized structure was studied by varying the annealing temperatures using X-ray diffraction (XRD). The XRD analysis indicates that annealing treatment promoted the ordered aggregation and crystallization of MEH-PPV: PC70BM films. Indeed, the blend ratio effect on the optical properties of MEH-PPV: PC70BM thin film was investigated. While, the effect of incorporation of PC70BM on the optical properties was studied using UV-Vis and photoluminescence (PL) measurement. We conclude that MEH-PPV: PC70BM (1:3) film leads to high charge transfer rate.

Influence of amines as surfactant on the optical, thermal, and structural properties of nanostructured ZnO

NASA Astrophysics Data System (ADS)

Sehgal, Preeti; Narula, A. K.

2015-06-01

Zinc oxide nanoparticles were synthesized by precipitation method using triethanolamine (TEA) and hexamine (HA) as capping agents, and their effects on the optical, thermal, and morphological properties were analyzed. We have also analyzed the role of solvents on the aforementioned properties of ZnO nanoparticles. The optical properties of capped zinc oxide nanoparticles were investigated by UV-visible and fluorescent techniques. The HA@ZnO and TEA@ZnO that showed blueshift in comparison with ZnO without surfactant revealed the role of surfactant in reducing the trap sites by forming defect-free nanoparticles. TG-DTA curves indicated that optimum annealing temperature for ZnO nanoparticles was in the range of 360-469 °C depending upon the surfactant and solvent; no weight loss was observed above 469 °C. Synthesized ZnO nanoparticles had pure wurtzite structure as elucidated by X-ray diffraction studies (XRD). Scanning electron microscope revealed that the ZnO synthesized in isopropyl alcohol had spherical morphology, whereas ZnO nanoparticles synthesized in methanol had agglomerate sheet-like structure. The average size of the nanocrystal was estimated around 85-169 nm for ZnO.

Study of nanoparticles TiO2 thin films on p-type silicon substrate using different alcoholic solvents

NASA Astrophysics Data System (ADS)

Muaz, A. K. M.; Hashim, U.; Arshad, M. K. Md.; Ruslinda, A. R.; Ayub, R. M.; Gopinath, Subash C. B.; Voon, C. H.; Liu, Wei-Wen; Foo, K. L.

2016-07-01

In this paper, sol-gel method spin coating technique is adopted to prepare nanoparticles titanium dioxide (TiO2) thin films. The prepared TiO2 sol was synthesized using titanium butoxide act as a precursor and subjected to deposited on the p-type silicon oxide (p-SiO2) and glass slide substrates under room temperature. The effect of different alcoholic solvents of methanol and ethanol on the structural, morphological, optical and electrical properties were systematically investigated. The coated TiO2 thin films were annealed in furnace at 773 K for 1 h. The structural properties of the TiO2 films were examined with X-ray Diffraction (XRD). From the XRD analysis, both solvents showing good crystallinity with anatase phase were the predominant structure. Atomic Force Microscopy (AFM) was employed to study the morphological of the thin films. The optical properties were investigated by Ultraviolet-visible (UV-Vis) spectroscopy were found that ethanol as a solvent give a higher optical transmittance if compare to the methanol solvent. The electrical properties of the nanoparticles TiO2 thin films were measured using two-point-probe technique.

Adaptive optics scanning laser ophthalmoscopy for in vivo imaging of lamina cribrosa

NASA Astrophysics Data System (ADS)

Vilupuru, Abhiram S.; Rangaswamy, Nalini V.; Frishman, Laura J.; Smith, Earl L., III; Harwerth, Ronald S.; Roorda, Austin

2007-05-01

The lamina cribrosa has been postulated from in vitro studies as an early site of damage in glaucoma. Prior in vivo measures of laminar morphology have been confounded by ocular aberrations. In this study the lamina cribrosa was imaged after correcting for ocular aberrations using the adaptive optics scanning laser ophthalmoscope (AOSLO) in normal and glaucomatous eyes of rhesus monkeys. All measured laminar morphological parameters showed increased magnitudes in glaucomatous eyes relative to fellow control eyes, indicating altered structure. The AOSLO provides high-quality images of the lamina cribrosa and may have potential as a tool for early identification of glaucoma.

Tailoring and optimization of optical properties of CdO thin films for gas sensing applications

NASA Astrophysics Data System (ADS)

Rajput, Jeevitesh K.; Pathak, Trilok K.; Kumar, V.; Swart, H. C.; Purohit, L. P.

2018-04-01

Cadmium oxide (CdO) thin films have been deposited onto glass substrates using different molar concentrations (0.2 M, 0.5 M and 0.8 M) of cadmium acetate precursor solutions using a sol-gel spin coating technique. The structural, morphological, optical and electrical results are presented. X-ray diffraction patterns indicated that the CdO films of different molarity have a stable cubic structure with a (111) preferred orientation at low molar concentration. Scanning electron microscopy images revealed that the films adopted a rectangular to cauliflower like morphology. The optical transmittance of the thin films was observed in the range 200-800 nm and it was found that the 0.2 M CdO thin films showed about 83% transmission in the visible region. The optical band gap energy of the thin films was found to vary from 2.10 to 3.30 eV with the increase in molar concentration of the solution. The electrical resistance of the 0.5 M thin film was found to be 1.56 kΩ. The oxygen sensing response was observed between 20-33% in the low temperature range (32-200 °C).

Effect of Cr doping on the structural, morphological, optical and electrical properties of indium tin oxide films

NASA Astrophysics Data System (ADS)

Mirzaee, Majid; Dolati, Abolghasem

2015-03-01

We report on the preparation and characterization of high-purity chromium (0.5-2.5 at.%)-doped indium tin oxide (ITO, In:Sn = 90:10) films deposited by sol-gel-mediated dip coating. The effects of different Cr-doping contents on structural, morphological, optical and electrical properties of the films were characterized by means of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), UV-Vis spectroscopy and four-point probe methods. XRD showed high phase purity cubic In2O3 and indicated a contraction of the lattice with Cr doping. FESEM micrographs show that grain size decreased with increasing the Cr-doping content. A method to determine chromium species in the sample was developed through the decomposition of the Cr 2 p XPS spectrum in Cr6+ and Cr3+ standard spectra. Optical and electrical studies revealed that optimum opto-electronic properties, including minimum sheet resistance of 4,300 Ω/Sq and an average optical transmittance of 85 % in the visible region with a band gap of 3.421 eV, were achieved for the films doped with Cr-doping content of 2 at.%.

The molten glass sewing machine

PubMed Central

Inamura, Chikara; Lizardo, Daniel; Franchin, Giorgia; Stern, Michael; Houk, Peter; Oxman, Neri

2017-01-01

We present a fluid-instability-based approach for digitally fabricating geometrically complex uniformly sized structures in molten glass. Formed by mathematically defined and physically characterized instability patterns, such structures are produced via the additive manufacturing of optically transparent glass, and result from the coiling of an extruded glass thread. We propose a minimal geometrical model—and a methodology—to reliably control the morphology of patterns, so that these building blocks can be assembled into larger structures with tailored functionally and optically tunable properties. This article is part of the themed issue ‘Patterning through instabilities in complex media: theory and applications’. PMID:28373379

Morphology-preserving chemical conversion of bioorganic and inorganic templates

NASA Astrophysics Data System (ADS)

Vernon, Jonathan Paul

The generation of nanostructured assemblies with complex (three-dimensional, 3D) self-assembled morphologies and with complex (multicomponent) tailorable inorganic compositions is of considerable technological and scientific interest. This dissertation demonstrates self-assembled 3D organic templates of biogenic origin can be converted into replicas comprised of numerous other functional nanocrystalline inorganic materials. Nature provides a spectacular variety of biologically-assembled 3D organic structures with intricate, hierarchical (macro-to-micro-to-nanoscale) morphologies. Such processing on readily-available structurally complex templates provides a framework for chemical conversion of synthetic organic templates and, potentially, production of organic/inorganic composites. Four specific research thrusts are detailed in this document. First, chemical conversion of a nanostructured bioorganic template into a multicomponent oxide compound (tetragonal BaTiO3) via SSG coating and subsequent morphology-preserving microwave hydrothermal processing is demonstrated. Second, morphology-preserving chemical conversion of bioorganic templates into hierarchical photoluminescent microparticles is demonstrated to reveal both the dramatic change in properties such processing can provide, and the potential utility of chemically transformed templates in anti-counterfeiting / authentication applications. Third, determination of the reaction mechanism(s) for morphology-preserving microwave hydrothermal conversion of TiO2 to BaTiO3, through Au inert markers on single crystal rutile titania, is detailed. Finally, utilization of constructive coating techniques (SSG) and moderate temperature (< 500°C) heat treatments to modify and replicate structural color is coupled with deconstructive focused ion beam microsurgery to prepare samples for microscale structure interrogation. Specifically, the effects of coating thickness and composition on reflection spectra of structurally colored templates are examined. Also, the effects of the replacement of natural material with higher index of refraction inorganic materials on optical properties are discussed. The three processing research thrusts constituting chapters 1, 2 and 4 take advantage of moderate temperature processing to ensure nanocrystalline materials, either for shape preservation or to prevent scattering in optical applications. The research thrust detailed in chapter 3 examines hydrothermal conversion of TiO2 to BaTiO3, not only to identify the reaction mechanism(s) involved in hydrothermal conversion under morphology-preserving conditions, but also to introduce inert marker experiments to the field of microwave hydrothermal processing.

Three Dimensional Characterization of Typical Urban and Desert Particles: Implications to Particle Optics

NASA Astrophysics Data System (ADS)

Goel, V.; Mishra, S.; Ahlawat, A. S.; Sharma, C.; Kotnala, R. K.

2017-12-01

Aerosol particles are generally considered as chemically homogeneous spheres in the retrieval techniques of ground and space borne observations which is not accurate approach and can lead to erroneous observations. For better simulation of optical and radiative properties of aerosols, a good knowledge of aerosol's morphology, chemical composition and internal structure is essential. Till date, many studies have reported the morphology and chemical composition of particles but very few of them provide internal structure and spatial distribution of different chemical species within the particle. The research on the effect of particle internal structure and its contribution to particle optics is extremely limited. In present work, we characterize the PM10 particles collected form typical arid (the Thar Desert, Rajasthan, India) and typical urban (New Delhi, India) environment using microscopic techniques. The particles were milled several times to investigate their internal structure. The EDS (Energy Dispersive X-ray Spectroscopy) spectra were recorded after each milling to check the variation in the chemical composition. In arid environment, Fe, Ca, C, Al, and Mg rich shell was observed over a Si rich particle whereas in urban environment, shell of Hg, Ag, C and N was observed over a Cu rich particle. Based on the observations, different model shapes [homogenous sphere and spheroid; heterogeneous sphere and spheroid; core shell] have been considered for assessing the associated uncertainties with the routine modeling of optical properties where volume equivalent homogeneous sphere approximation is considered. The details will be discussed during presentation.

Complex-Morphology Metal-Based Nanostructures: Fabrication, Characterization, and Applications

PubMed Central

Gentile, Antonella; Ruffino, Francesco; Grimaldi, Maria Grazia

2016-01-01

Due to their peculiar qualities, metal-based nanostructures have been extensively used in applications such as catalysis, electronics, photography, and information storage, among others. New applications for metals in areas such as photonics, sensing, imaging, and medicine are also being developed. Significantly, most of these applications require the use of metals in the form of nanostructures with specific controlled properties. The properties of nanoscale metals are determined by a set of physical parameters that include size, shape, composition, and structure. In recent years, many research fields have focused on the synthesis of nanoscale-sized metallic materials with complex shape and composition in order to optimize the optical and electrical response of devices containing metallic nanostructures. The present paper aims to overview the most recent results—in terms of fabrication methodologies, characterization of the physico-chemical properties and applications—of complex-morphology metal-based nanostructures. The paper strongly focuses on the correlation between the complex morphology and the structures’ properties, showing how the morphological complexity (and its nanoscale control) can often give access to a wide range of innovative properties exploitable for innovative functional device production. We begin with an overview of the basic concepts on the correlation between structural and optical parameters of nanoscale metallic materials with complex shape and composition, and the possible solutions offered by nanotechnology in a large range of applications (catalysis, electronics, photonics, sensing). The aim is to assess the state of the art, and then show the innovative contributions that can be proposed in this research field. We subsequently report on innovative, versatile and low-cost synthesis techniques, suitable for providing a good control on the size, surface density, composition and geometry of the metallic nanostructures. The main purpose of this study is the fabrication of functional nanoscale-sized materials, whose properties can be tailored (in a wide range) simply by controlling the structural characteristics. The modulation of the structural parameters is required to tune the plasmonic properties of the nanostructures for applications such as biosensors, opto-electronic or photovoltaic devices and surface-enhanced Raman scattering (SERS) substrates. The structural characterization of the obtained nanoscale materials is employed in order to define how the synthesis parameters affect the structural characteristics of the resulting metallic nanostructures. Then, macroscopic measurements are used to probe their electrical and optical properties. Phenomenological growth models are drafted to explain the processes involved in the growth and evolution of such composite systems. After the synthesis and characterization of the metallic nanostructures, we study the effects of the incorporation of the complex morphologies on the optical and electrical responses of each specific device. PMID:28335236

Starch-assisted synthesis and optical properties of ZnS nanoparticles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tian, Xiuying, E-mail: xiuyingt@yahoo.com; Wen, Jin; Wang, Shumei

Highlights: • ZnS spherical nanostructure was prepared via starch-assisted method. • The crystalline lattice structure, morphologies, chemical and optical properties of ZnS nanoparticles. • The forming mechanism of ZnS nanoparticles. • ZnS spherical nano-structure can show blue emission at 460–500 nm. - Abstract: ZnS nanoparticles are fabricated via starch-assisted method. The effects of different starch amounts on structure and properties of samples are investigated, and the forming mechanism of ZnS nanoparticles is discussed. By X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM) and selected area electron diffraction (SAED), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), ultraviolet–visible (UV–vis)more » spectroscopy and fluorescence (FL) spectrometer, their phases, crystalline lattice structure, morphologies, chemical and optical properties are characterized. The results show that ZnS has polycrystalline spherical structure with the mean diameter of 130 nm. Sample without starch reveals irregular aggregates with particle size distribution of 0.5–2 μm. The band gap value of ZnS is 3.97 eV. The chemical interaction exists between starch molecules and ZnS nanoparticles by hydrogen bonds. The stronger FL emission peaks of ZnS synthesized with starch, indicate a larger content of sulfur vacancies or defects than ZnS synthesized without starch.« less

Growth and Properties of Cl- Incorporated ZnO Nanofilms Grown by Ultrasonic Spray-Assisted Chemical Vapor Deposition.

PubMed

Chen, Tingfang; Wang, Aiji; Kong, Lingrui; Li, Yongliang; Wang, Yinshu

2016-04-01

Pure and Cl- incorporated ZnO nanofilms were grown by the ultrasonic spray-assisted chemical vapor deposition (CVD) method. The properties of the nanofilms were investigated. The effects of growth temperature and Cl- concentration on the crystal structure, morphology, and optical properties of the nanofilms were studied. Temperature plays an important role in the growth mode and morphology of the pure nanofilms. Preferential growth along the c-axis occurs only at modulating temperature. Lower temperature suppresses the preferential growth, and higher temperature suppresses the growth of the nanofilms. The morphologies of the nanofilms change from lamellar and spherical structures into hexagonal platelets, then into separated nanoparticles with an increase in the temperature. Incorporating Cl- results in the lattice contracting gradually along with c-axis. Grains composing the nanofilms refine, and the optical gap broadens with increasing of Cl- concentration in growth precursor. Incorporating Cl- could reduce oxygen vacancies and passivate the non-irradiated centers, thus enhancing the UV emission and suppressing the visible emission of ZnO nanofilms.

Microcavity morphology optimization

NASA Astrophysics Data System (ADS)

Ferdous, Fahmida; Demchenko, Alena A.; Vyatchanin, Sergey P.; Matsko, Andrey B.; Maleki, Lute

2014-09-01

High spectral mode density of conventional optical cavities is detrimental to the generation of broad optical frequency combs and to other linear and nonlinear applications. In this work we optimize the morphology of high-Q whispering gallery (WG) and Fabry-Perot (FP) cavities and find a set of parameters that allows treating them, essentially, as single-mode structures, thus removing limitations associated with a high density of cavity mode spectra. We show that both single-mode WGs and single-mode FP cavities have similar physical properties, in spite of their different loss mechanisms. The morphology optimization does not lead to a reduction of quality factors of modes belonging to the basic family. We study the parameter space numerically and find the region where the highest possible Q factor of the cavity modes can be realized while just having a single bound state in the cavity. The value of the Q factor is comparable with that achieved in conventional cavities. The proposed cavity structures will be beneficial for generation of octave spanning coherent frequency combs and will prevent undesirable effects of parametric instability in laser gravitational wave detectors.

Effect of aluminium doping on structural and optical properties of ZnO thin films by sol-gel method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vijayaprasath, G.; Murugan, R.; Ravi, G., E-mail: raviganesa@rediffmail.com, E-mail: gravicrc@gmail.com

2015-06-24

We systematically investigated the structural, morphological and optical properties of 0.05 mol % Al doped ZnO (Al:ZnO) thin films deposited on glass substrates by sol-gel spin coating method. The influences of Al doping in ZnO thin films are characterized by Powder X-ray diffraction study. ZnO and Al:ZnO thin films have showed hexagonal wurtzite structure without any secondary phase in c-axis (002) orientation. The SEM images also proved the hexagonal rod like morphologies for both films. All the films exhibited transmittance of 70-80% in the visible range up to 800 nm and cut-off wavelength observed at ∼390 nm corresponding to the fundamental absorption ofmore » ZnO. The band gap of the ZnO thin films slightly widened with the Al doping. The photoluminescence properties have been studied for Al: ZnO thin films and the results are presented in detail.« less

Structure and optical properties of ZnO produced from microwave hydrothermal hydrolysis of tris(ethylenediamine)zinc nitrate complex

NASA Astrophysics Data System (ADS)

Mostafa, Nasser Y.; Heiba, Zein K.; Ibrahim, Mohamed M.

2015-01-01

ZnO powders were synthesized using a solution microwave hydrothermal hydrolysis process and tris(ethylenediamine)zinc nitrate {[Zn(en)3](NO3)2} (en = ethylenediamine) as a precursor. Hydrolysis of the precursor complex at different pH produced zinc oxide with a diversity of well-defined morphologies. The effect of hydrolysis pH values on the structural and optical properties has been explored using XRD, SEM, and UV-visible diffuse reflectance spectroscopy (DRS). At pH = 7.0, randomly dispersed rods were formed. Whereas flower-like morphologies were obtained by treating the complex precursor in water at pH = 10.0 and 12.0. The ZnO4 tetrahedrons are greatly affected by the pH value. The band gap decreased sharply with increasing the pH value from 7.0 to 10.0, then slightly decreased with further increasing the pH to 12.0. The relationship between band gap and both structure and surface defects of the samples is also discussed.

Structure, Morphology and Optical Properties of TiO2 Films Formed by Anodizing in a Mixed Solution of Citric Acid and Sulfamic Acid

NASA Astrophysics Data System (ADS)

Choudhary, R. K.; Sarkar, P.; Biswas, A.; Mishra, P.; Abraham, G. J.; Sastry, P. U.; Kain, V.

2017-08-01

TiO2 films of 50-180 nm thickness were formed at room temperature by anodization of titanium metal in a mixture of citric acid and sulfamic acid in the potential range of 5-30 V. The films so obtained were characterized for their crystal structure, surface morphology, chemical composition and optical properties. Grazing incidence x-ray diffraction and micro-laser Raman spectroscopy measurements of the anodic films confirmed the formation of brookite phase of TiO2 at anodizing potentials of 15, 20, 25 and 30 V and amorphous structure at 5 and 10 V. Field emission scanning electron microscopy revealed non-porous microstructure of the films. Spectroscopic ellipsometry measurements evaluated the band gap of TiO2 at around 3.3 eV, whereas the refractive index of the films was found to be in the range of 2-2.35, in the visible range of spectrum.

Internal energy flows in composite optical vortices

NASA Astrophysics Data System (ADS)

Ferrer-Garcia, Manuel F.; Lopez-Mago, Dorilian; Hernandez-Aranda, Raul I.

2016-09-01

We study the energy ow pattern in the superposition of two off-axis optical vortices with orthogonal polarization states. This system presents a rich structure of polarization singularities, which allows us to study the transverse spin and orbital angular momentum of different polarization morphologies, which includes C points (stars, lemons and monstars) and L lines. We perform numerical simulations of the optical forces acting on submicron particles and show interesting configurations. We provide the set of control parameters to unambiguously distinguish between the spin and orbital ow contributions.

Mimicking lizard-like surface structures upon ultrashort laser pulse irradiation of inorganic materials

NASA Astrophysics Data System (ADS)

Hermens, U.; Kirner, S. V.; Emonts, C.; Comanns, P.; Skoulas, E.; Mimidis, A.; Mescheder, H.; Winands, K.; Krüger, J.; Stratakis, E.; Bonse, J.

2017-10-01

Inorganic materials, such as steel, were functionalized by ultrashort laser pulse irradiation (fs- to ps-range) to modify the surface's wetting behavior. The laser processing was performed by scanning the laser beam across the surface of initially polished flat sample material. A systematic experimental study of the laser processing parameters (peak fluence, scan velocity, line overlap) allowed the identification of different regimes associated with characteristic surface morphologies (laser-induced periodic surface structures, grooves, spikes, etc.). Analyses of the surface using optical as well as scanning electron microscopy revealed morphologies providing the optimum similarity to the natural skin of lizards. For mimicking skin structures of moisture-harvesting lizards towards an optimization of the surface wetting behavior, additionally a two-step laser processing strategy was established for realizing hierarchical microstructures. In this approach, micrometer-scaled capillaries (step 1) were superimposed by a laser-generated regular array of small dimples (step 2). Optical focus variation imaging measurements finally disclosed the three dimensional topography of the laser processed surfaces derived from lizard skin structures. The functionality of these surfaces was analyzed in view of wetting properties.

Annealing dependence on flexible p-CuGaO2/n-ZnO heterojunction diode deposited by RF sputtering method

NASA Astrophysics Data System (ADS)

Li Lam, Mui; Hafiz Abu Bakar, Muhammad; Lam, Wai Yip; Alias, Afishah; Rahman, Abu Bakar Abd; Anuar Mohamad, Khairul; Uesugi, Katsuhiro

2017-11-01

In this work, p-CuGaO2/n-ZnO heterojunction diodes were deposited by RF powered sputtering method on polyethylene terephthalate (PETP, PET) substrates. Structural, morphology, optical and electrical properties of CuGaO2/ZnO heterojunction was investigated as a function of annealing duration. The structural properties show the ZnO films (002) peak were stronger at the range of 34° while CuGaO2 (015) peak is not visible at 44°. The surface morphology revealed that RMS roughness become smoother as the annealing duration increase to 30 minutes and become rougher as the annealing duration is increased to 60 minutes. The optical properties of CuGaO2/ZnO heterojunction diode at 30 minutes exhibit approximately 75% optical transmittance in the invisible region. The diodes exhibited a rectifying characteristic and the maximum forward current was observed for the diode annealed for 30 minutes. The diodes show an ideality factor range from 43.69 to 71.29 and turn on voltage between 0.75 V and 1.05 V.

Elemental, morphological, structural, optical, and magnetic properties of erbium doped ZnO nanoparticles

NASA Astrophysics Data System (ADS)

Poornaprakash, B.; Chalapathi, U.; Purusottam Reddy, B.; Prabhakar Vattikuti, S. V.; Siva Pratap Reddy, M.; Park, Si-Hyun

2018-03-01

The sensible tuning of the structural, optical, and magnetic properties of ZnO nanoparticles (NPs) with suitable doping can enhance their applicability in diverse fields. In this study, we synthesized ZnO NPs with Er (0-4 at%) doping and their elemental, structural, optical, and magnetic properties were studied. Both field emission scanning electron microscopy (FESEM) and high resolution transmission electron microscopy (HRTEM) studies of the suspensions consist of hexagonal shaped NPs. All the prepared NPs exhibited hexagonal phase as demonstrated by powder x-ray diffraction studies. A blue shift was observed in the Er doped ZnO NPs compared to pure ZnO, indicating the increased optical bandgap. Vibrating sample magnetometer studies exhibited the pure ZnO NPs was typical diamagnetic feature whereas all the Er doped ZnO NPs were paramagnetic feature at 300 K. This is the first paramagnetic report on Er doped ZnO NPs.

The effect of cation doping on the morphology, optical and structural properties of highly oriented wurtzite ZnO-nanorod arrays grown by a hydrothermal method

NASA Astrophysics Data System (ADS)

Hassanpour, A.; Guo, P.; Shen, S.; Bianucci, P.

2017-10-01

Undoped and C-doped (C: Mg2+, Ni2+, Mn2+, Co2+, Cu2+, Cr3+) ZnO nanorods were synthesized by a hydrothermal method at temperatures as low as 60 °C. The effect of doping on the morphology of the ZnO nanorods was visualized by taking their cross section and top SEM images. The results show that the size of nanorods was increased in both height and diameter by cation doping. The crystallinity change of the ZnO nanorods due to each doping element was thoroughly investigated by an x-ray diffraction (XRD). The XRD patterns show that the wurtzite crystal structure of ZnO nanorods was maintained after cation addition. The optical Raman-active modes of undoped and cation-doped nanorods were measured with a micro-Raman setup at room temperature. The surface chemistry of samples was investigated by x-ray photoelectron spectroscopy and energy-dispersive x-ray spectroscopy. Finally, the effect of each cation dopant on band-gap shift of the ZnO nanorods was investigated by a photoluminescence setup at room temperature. Although the amount of dopants (Mg2+, Ni2+, and Co2+) was smaller than the amount of Mn2+, Cu2+, and Cr3+ in the nanorods, their effect on the band structure of the ZnO nanorods was profound. The highest band-gap shift was achieved for a Co-doped sample, and the best crystal orientation was for Mn-doped ZnO nanorods. Our results can be used as a comprehensive reference for engineering of the morphological, structural and optical properties of cation-doped ZnO nanorods by using a low-temperature synthesis as an economical mass-production approach.

Synthesis-driven, structure-dependent optical behavior in phase-tunable NaYF 4:Yb,Er-based motifs and associated heterostructures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Haiqing; Han, Jinkyu; McBean, Coray

Understanding the key parameters necessary for generating uniform Er,Yb co-activated NaYF 4 possessing various selected phases (i.e. cubic or hexagonal) represents an important chemical strategy towards tailoring optical behavior in these systems. In this paper, we report on a straightforward hydrothermal synthesis in which the separate effects of reaction temperature, reaction time, and precursor stoichiometry in the absence of any surfactant were independently investigated. Interestingly, the presence and the concentration of NH 4OH appear to be the most critical determinants of the phase and morphology. For example, with NH 4OH as an additive, we have observed the formation of novelmore » hierarchical nanowire bundles which possess overall lengths of ~5 μm and widths of ~1.5 μm but are composed of constituent component sub-units of long, ultrathin (~5 nm) nanowires. These motifs have yet to be reported as distinctive morphological manifestations of fluoride materials. The optical properties of as-generated structures have also been carefully analyzed. Specifically, we have observed tunable, structure-dependent energy transfer behavior associated with the formation of a unique class of NaYF 4–CdSe quantum dot (QD) heterostructures, incorporating zero-dimensional (0D), one-dimensional (1D), and three-dimensional (3D) NaYF 4 structures. Our results have demonstrated the key roles of the intrinsic morphology-specific physical surface area and porosity as factors in governing the resulting opto-electronic behavior. Finally and specifically, the trend in energy transfer efficiency correlates well with the corresponding QD loading within these heterostructures, thereby implying that the efficiency of FRET appears to be directly affected by the amount of QDs immobilized onto the external surfaces of the underlying fluoride host materials.« less

Synthesis-driven, structure-dependent optical behavior in phase-tunable NaYF 4:Yb,Er-based motifs and associated heterostructures

DOE PAGES

Liu, Haiqing; Han, Jinkyu; McBean, Coray; ...

2017-01-03

Understanding the key parameters necessary for generating uniform Er,Yb co-activated NaYF 4 possessing various selected phases (i.e. cubic or hexagonal) represents an important chemical strategy towards tailoring optical behavior in these systems. In this paper, we report on a straightforward hydrothermal synthesis in which the separate effects of reaction temperature, reaction time, and precursor stoichiometry in the absence of any surfactant were independently investigated. Interestingly, the presence and the concentration of NH 4OH appear to be the most critical determinants of the phase and morphology. For example, with NH 4OH as an additive, we have observed the formation of novelmore » hierarchical nanowire bundles which possess overall lengths of ~5 μm and widths of ~1.5 μm but are composed of constituent component sub-units of long, ultrathin (~5 nm) nanowires. These motifs have yet to be reported as distinctive morphological manifestations of fluoride materials. The optical properties of as-generated structures have also been carefully analyzed. Specifically, we have observed tunable, structure-dependent energy transfer behavior associated with the formation of a unique class of NaYF 4–CdSe quantum dot (QD) heterostructures, incorporating zero-dimensional (0D), one-dimensional (1D), and three-dimensional (3D) NaYF 4 structures. Our results have demonstrated the key roles of the intrinsic morphology-specific physical surface area and porosity as factors in governing the resulting opto-electronic behavior. Finally and specifically, the trend in energy transfer efficiency correlates well with the corresponding QD loading within these heterostructures, thereby implying that the efficiency of FRET appears to be directly affected by the amount of QDs immobilized onto the external surfaces of the underlying fluoride host materials.« less

Performance improvement of long-range surface plasmon structure for use in an all-optical switch

NASA Astrophysics Data System (ADS)

Jandaghian, Ali; Lotfalian, Ali; Kouhkan, Mohsen; Mohajerani, Ezeddin

2017-12-01

This paper presents important parameters in performance of long-range surface plasmon (LRSP) structure (SF4/PVA/silver/PMMA-DR1) that are improved. We select poly(vinyl alcohol) (PVA) as the first dielectric layer due to its water solubility and good optical properties. The thickness of PVA and silver layers is optimized by transfer matrix method based on Fresnel equations. Surface morphologies of PVA and silver surfaces are analyzed by AFM imaging due to their important role in the performance of an LRSP structure. Furthermore, the sensitivity of an all-optical switch based on plasmon is investigated. In order to compare the sensitivity of LRSP and conventional surface plasmon (SP) structures in switching mode, full wide of half maximum, resonance angles, and pump powers of both structures are measured by a custom-made optical setup based on angular interrogation with a precision of 0.01 deg. Finally, we conclude that for creating equal signal levels in both samples, the required pump power for LRSP structure was about three times less than that for conventional SP; thus, these results led to power savings in optical switches.

Chemical spray pyrolyzed kesterite Cu2ZnSnS4 (CZTS) thin films

NASA Astrophysics Data System (ADS)

Khalate, S. A.; Kate, R. S.; Deokate, R. J.

2018-04-01

Pure kesterite phase thin films of Cu2ZnSnS4 (CZTS) were synthesized at different substrate temperatures using sulphate precursors by spray pyrolysis method. The significance of synthesis temperature on the structural, morphological and optical properties has been studied. The X-ray analysis assured that synthesized CZTS thin films showing pure kesterite phase. The value of crystallite size was found maximum at the substrate temperature 400 °C. At the same temperature, microstructural properties such as dislocation density, micro-strain and stacking fault probability were found minimum. The morphological examination designates the development of porous and uniform CZTS thin films. The synthesized CZTS thin films illustrate excellent optical absorption (105 cm-1) in the visible band and the optical band gap varies in the range of 1.489 eV to 1.499 eV.

Morphological, Structural and Optical Evolution of Ag Nanostructures on c-Plane GaN Through the Variation of Deposition Amount and Temperature

NASA Astrophysics Data System (ADS)

Sui, Mao; Li, Ming-Yu; Pandey, Puran; Zhang, Quanzhen; Kunwar, Sundar; Lee, Jihoon

2018-03-01

Owing to their tunable properties, Ag nanostructures have been widely adapted in various applications and the morphological control can determine their performance and effectiveness. In this work, we demonstrate the morphological and optical evolution of Ag nanostructures on GaN (0001) by the systematic control of deposition amount at two distinctive annealing temperatures. Based on the Volmer-Weber and coalescence growth models, the nanostructure growth commenced by the thermal solid-state-dewetting evolve in terms of size, density and configuration. At 450 °C, the round-dome shaped Ag nanoparticles (regime I), irregular Ag nano-mounds (regime II) and void-layer structures (regime III) are observed along with the gradually increased deposition amount. As a sharp distinction, the solid state dewetting process occur more radically at 700 °C and also, the Ag sublimation and the effect on the nanostructure formation are observed in a clear regime shift scaled by the deposition amount. Meanwhile, a strong dependency of reflectance spectra evolution on the Ag nanostructure morphology is witnessed for both sets. In particular, Ag dipolar resonance peaks are significantly red-shifted from VIS to NIR regions along with the nanostructure evolution. The reflectance, PL and Raman intensity variation are also observed and discussed based on the evolution of Ag nanostructures.

Identification of the layered morphology of the esophageal wall by optical coherence tomography

PubMed Central

Yokosawa, Satoshi; Koike, Tomoyuki; Kitagawa, Yasushi; Hatta, Waku; Uno, Kaname; Abe, Yasuhiko; Iijima, Katsunori; Imatani, Akira; Ohara, Shuichi; Shimosegawa, Tooru

2009-01-01

AIM: To assess each layer of the optical coherence tomography (OCT) image of the esophageal wall with reference to the histological structure. METHODS: Resected specimens of fresh pig esophagus was used as a model for the esophageal wall. We injected cyanoacrylate adhesive into the specimens to create a marker, and scanned them using a miniature OCT probe. The localization of these markers was assessed in the OCT images. Then we compared the OCT-imaged morphology with the corresponding histological section, guided by the cyanoacrylate adhesive markers. We prepared a second set of experiments using nylon sutures as markers. RESULTS: The OCT image of the esophageal specimen has a clear five-layered morphology. First, it consisted of a relatively less reflective layer; second, a more reflective layer; third, a less reflective layer; fourth, a more reflective layer; and fifth, a less reflective layer. Comparing the OCT images with marked histological sections showed that the first layer corresponded to stratified squamous epithelium; the second to lamina propria; the third to muscularis mucosa; fourth, submucosa; and fifth, muscularis propria with deeper structures of the esophageal wall. CONCLUSION: We demonstrated that the OCT image of the normal esophageal wall showed a five-layered morphology, which corresponds to histological esophageal wall components. PMID:19764091

Identification of the layered morphology of the esophageal wall by optical coherence tomography.

PubMed

Yokosawa, Satoshi; Koike, Tomoyuki; Kitagawa, Yasushi; Hatta, Waku; Uno, Kaname; Abe, Yasuhiko; Iijima, Katsunori; Imatani, Akira; Ohara, Shuichi; Shimosegawa, Tooru

2009-09-21

To assess each layer of the optical coherence tomography (OCT) image of the esophageal wall with reference to the histological structure. Resected specimens of fresh pig esophagus was used as a model for the esophageal wall. We injected cyanoacrylate adhesive into the specimens to create a marker, and scanned them using a miniature OCT probe. The localization of these markers was assessed in the OCT images. Then we compared the OCT-imaged morphology with the corresponding histological section, guided by the cyanoacrylate adhesive markers. We prepared a second set of experiments using nylon sutures as markers. The OCT image of the esophageal specimen has a clear five-layered morphology. First, it consisted of a relatively less reflective layer; second, a more reflective layer; third, a less reflective layer; fourth, a more reflective layer; and fifth, a less reflective layer. Comparing the OCT images with marked histological sections showed that the first layer corresponded to stratified squamous epithelium; the second to lamina propria; the third to muscularis mucosa; fourth, submucosa; and fifth, muscularis propria with deeper structures of the esophageal wall. We demonstrated that the OCT image of the normal esophageal wall showed a five-layered morphology, which corresponds to histological esophageal wall components.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sharma, Rabindar K., E-mail: rkrksharma6@gmail.com; Reddy, G. B., E-mail: rkrksharma6@gmail.com

In this report, we synthesize vertically aligned molybdenum trioxide (α−MoO{sub 3}) nanoflakes (NFs) with high aspect ratio (height/thickness >15) on the cobalt coated glass substrates by the plasma assisted sublimation process, employing Mo metal strip as a sublimation source. The effect of substrate temperature, nature of substrate as well as the geometry of the sublimation source (Mo-strip) have been investigated on the morphological, structural and optical properties of the grown NFs, keeping plasma parameters as fixed. The surface morphology, crystalline structure and optical properties of MoO{sub 3} NFs have been studied systematically by using scanning electron microscope (SEM), transmission electronmore » microscope (TEM) with selected area electron diffraction (SAED), X-ray diffractometer, and IR- spectroscopy. The experimental observations endorse that the characteristics of MoO{sub 3} NFs are strongly depend on substrate temperature, substrate nature as well as geometry of Mo-strip. All the observed results are well in consonance with each other.« less

Effect of heat treatment on morphological, structural and optical properties of CoMTPP thin films

NASA Astrophysics Data System (ADS)

El-Nahass, M. M.; Ammar, A. H.; Farag, A. A. M.; Atta, A. A.; El-Zaidia, E. F. M.

2011-03-01

The morphologies and crystal structures of 5,10,15,20-tetrakis(4-methoxyphenyl)-21 H,23 H-porphine cobalt(II), CoMTPP, thin films were investigated by scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively. Optical constants namely the refractive index, n, and the absorption index, k, of CoMTPP were estimated by using spectrophotometric measurements of transmittance and reflectance in the spectral range from 200 to 2500 nm. The dispersion of the refractive index in terms of the single oscillator in the transparent region is discussed. The single oscillator energy ( E0), the dispersion energy ( E d), the high frequency dielectric constant ( ɛ∞) and the lattice dielectric constant ( ɛ L) were calculated. The analysis of the spectral behavior of the absorption coefficient in the intrinsic absorption region reveals two indirect allowed transitions for as-deposited and annealed films.

Three Dimensional Mesoscale Analysis of Translamellar Cross-Bridge Morphologies in the Annulus Fibrosus using Optical Coherence Tomography

PubMed Central

Han, Sang Kuy; Chen, Chao-Wei; Wierwille, Jerry; Chen, Yu; Hsieh, Adam H.

2014-01-01

The defining characteristic of the annulus fibrosus (AF) of the intervertebral disc (IVD) has long been the lamellar structures that consist of highly ordered collagen fibers arranged in alternating oblique angles from one layer to the next. However, a series of recent histologic studies have demonstrated that AF lamellae contain elastin- and type VI collagen-rich secondary “cross-bridge” structures across lamellae. In this study, we use optical coherence tomography (OCT) to elucidate the three-dimensional (3D) morphologies of these translamellar cross-bridge in AF tissues. Mesoscale volumetric images by OCT reveal a highly heterogeneous spatial network and distribution of 3-D translamellar cross-bridges. The results of this study confirm the translamellar cross-bridge is identified as a distinguishable structure, which is laid in the interbundle space of adjacent lamellae and crisscrosses multiple lamellae in the radial direction. In contrast to previously proposed models extrapolated from 2-D sections, results from this current study show that translamellar cross-bridges exist as a complex, interconnected network. We also found much greater variation in lengths of cross-bridges within the interbundle space of lamellae (0.8-1.4 mm from the current study versus 0.3-0.6 mm from 2-D sections). OCT-based 3-D morphology of translamellar cross-bridge provides novel insight into the AF structure. PMID:25564974

Annealing Temperature Dependent Structural and Optical Properties of RF Sputtered ZnO Thin Films.

PubMed

Sharma, Shashikant; Varma, Tarun; Asokan, K; Periasamy, C; Boolchandani, Dharmendar

2017-01-01

This work investigates the effect of annealing temperature on structural and optical properties of ZnO thin films grown over Si 100 and glass substrates using RF sputtering technique. Annealing temperature has been varied from 300 °C to 600 °C in steps of 100, and different microstructural parameters such as grain size, dislocation density, lattice constant, stress and strain have been evaluated. The structural and surface morphological characterization has been done using X-ray Diffraction (XRD) and Scanning Electron Microscope (SEM). XRD analysis reveals that the peak intensity of 002 crystallographic orientation increases with increased annealing temperature. Optical characterization of deposited films have been done using UV-Vis-NIR spectroscopy and photoluminescence spectrometer. An increase in optical bandgap of deposited ZnO thin films with increasing annealing temperature has been observed. The average optical transmittance was found to be more than 85% for all deposited films. Photoluminiscense spectra (PL) suggest that the crystalline quality of deposited film has increased at higher annealing temperature.

Efficacy of saccharides bio-template on structural, morphological, optical and antibacterial property of ZnO nanoparticles.

PubMed

Dhanalakshmi, A; Palanimurugan, A; Natarajan, B

2018-09-01

Mono, di and polysaccharides of glucose (C 6 H 12 O 6 ), sucrose (C 12 H 24 O 12 ) and starch (C 6 H 12 O 6 ) n bio-template ZnO nanoparticles (NPs) has prepared by chemical precipitation method. Saccharides bio-template ZnO (SBts-ZnO) NPs were efficiently prepared for their structural and optical properties were examined by using XRD, FE-SEM, AFM, FTIR, UV and PL techniques. All the samples are polycrystalline nature with a preferential orientation depending on the (1 0 1) plane. The reduction of crystalline size by utilizing glucose, sucrose and starch bio-template of ZnO NPs. FE-SEM images revealed that the spherical and nano-rods like morphologies for ZnO and SBts-ZnO NPs respectively. AFM recorded images shows spherical features that confirmed and also the morphological changes were noticed with the addition of polymers. Interaction of bio-templated saccharides (glucose G 1 , sucrose S 2 & starch S n ) molecules was proved by FTIR study. Optical absorbance and emission behaviours were investigated using UV-Vis and photoluminescence techniques. The antibacterial study revealed that SBts-ZnO have excellent antibacterial effect than ZnO. The S n -ZnO sample has potent antibacterial activity against the Proteus vulgaris followed by Klebsiella pneumoniae, Escherichia coli and Staphylococcus aureus. Copyright © 2018 Elsevier B.V. All rights reserved.

Structural and optical properties of vanadium ion-implanted GaN

NASA Astrophysics Data System (ADS)

Macková, A.; Malinský, P.; Jagerová, A.; Sofer, Z.; Klímová, K.; Sedmidubský, D.; Mikulics, M.; Lorinčík, J.; Veselá, D.; Böttger, R.; Akhmadaliev, S.

2017-09-01

The field of advanced electronic and optical devices searches for a new generation of transistors and lasers. The practical development of these novel devices depends on the availability of materials with the appropriate magnetic and optical properties, which is strongly connected to the internal morphology and the structural properties of the prepared doped structures. In this contribution, we present the characterisation of V ion-doped GaN epitaxial layers. GaN layers, oriented along the (0 0 0 1) crystallographic direction, grown by low-pressure metal-organic vapour-phase epitaxy (MOVPE) on c-plane sapphire substrates were implanted with 400 keV V+ ions at fluences of 5 × 1015 and 5 × 1016 cm-2. Elemental depth profiling was accomplished by Rutherford Backscattering Spectrometry (RBS) and Secondary Ion Mass Spectrometry (SIMS) to obtain precise information about the dopant distribution. Structural investigations are needed to understand the influence of defect distribution on the crystal-matrix recovery and the desired structural and optical properties. The structural properties of the ion-implanted layers were characterised by RBS-channelling and Raman spectroscopy to get a comprehensive insight into the structural modification of implanted GaN and to study the influence of subsequent annealing on the crystalline matrix reconstruction. Photoluminescence measurement was carried out to check the optical properties of the prepared structures.

Electrochemical Supercapacitive Performance of Spray-Deposited NiO Electrodes

NASA Astrophysics Data System (ADS)

Yadav, Abhijit A.; Chavan, U. J.

2018-04-01

Transition-metal oxides with porous structure are considered for use as promising electrodes for high-performance supercapacitors. Nanocrystalline nickel oxide (NiO) thin films have been prepared as active material for supercapacitors by spray pyrolysis. In this study, the effects of the film thickness on its structural, morphological, optical, electrical, and electrochemical properties were studied. X-ray diffraction analysis revealed cubic structure with average crystalline size of around 21 nm. Scanning electron microscopy showed porous morphology. The optical bandgap decreased from 3.04 eV to 2.97 eV with increase in the film thickness. Electrical resistivity measurements indicated semiconducting behavior. Cyclic voltammetry and galvanostatic charge/discharge study revealed good pseudocapacitive behavior. Specific capacitance of 564 F g-1 at scan rate of 5 mV s-1 and 553 F g-1 at current density of 1 A g-1 was observed. An NiO-based supercapacitor delivered specific energy of 22.8 W h kg-1 at specific power of 2.16 kW kg-1, and retained 93.01% specific capacitance at current density of 1 A g-1 after 1000 cycles. Therefore, taking advantage of the porous morphology that exists in the nanostructure, such NiO materials can be considered for use as promising electrodes for high-performance supercapacitors.

Structure, Electronic Properties, and Electrochemical Behavior of a Boron-Doped Diamond/Quartz Optically Transparent Electrode.

PubMed

Wächter, Naihara; Munson, Catherine; Jarošová, Romana; Berkun, Isil; Hogan, Timothy; Rocha-Filho, Romeu C; Swain, Greg M

2016-10-26

The morphology, microstructure, chemistry, electronic properties, and electrochemical behavior of a boron-doped nanocrystalline diamond (BDD) thin film grown on quartz were evaluated. Diamond optically transparent electrodes (OTEs) are useful for transmission spectroelectrochemical measurements, offering excellent stability during anodic and cathodic polarization and exposure to a variety of chemical environments. We report on the characterization of a BDD OTE by atomic force microscopy, optical spectroscopy, Raman spectroscopic mapping, alternating-current Hall effect measurements, X-ray photoelectron spectroscopy, and electrochemical methods. The results reported herein provide the first comprehensive study of the relationship between the physical and chemical structure and electronic properties of a diamond OTE and the electrode's electrochemical activity.

Non-destructive optical clearing technique enhances optical coherence tomography (OCT) for real-time, 3D histomorphometry of brain tissue (Conference Presentation)

NASA Astrophysics Data System (ADS)

Paul, Akshay; Chang, Theodore H.; Chou, Li-Dek; Ramalingam, Tirunelveli S.

2016-03-01

Evaluation of neurodegenerative disease often requires examination of brain morphology. Volumetric analysis of brain regions and structures can be used to track developmental changes, progression of disease, and the presence of transgenic phenotypes. Current standards for microscopic investigation of brain morphology are limited to detection of superficial structures at a maximum depth of 300μm. While histological techniques can provide detailed cross-sections of brain structures, they require complicated tissue preparation and the ultimate destruction of the sample. A non-invasive, label-free imaging modality known as Optical Coherence Tomography (OCT) can produce 3-dimensional reconstructions through high-speed, cross-sectional scans of biological tissue. Although OCT allows for the preservation of intact samples, the highly scattering and absorbing properties of biological tissue limit imaging depth to 1-2mm. Optical clearing agents have been utilized to increase imaging depth by index matching and lipid digestion, however, these contemporary techniques are expensive and harsh on tissues, often irreversibly denaturing proteins. Here we present an ideal optical clearing agent that offers ease-of-use and reversibility. Similar to how SeeDB has been effective for microscopy, our fructose-based, reversible optical clearing technique provides improved OCT imaging and functional immunohistochemical mapping of disease. Fructose is a natural, non-toxic sugar with excellent water solubility, capable of increasing tissue transparency and reducing light scattering. We will demonstrate the improved depth-resolving performance of OCT for enhanced whole-brain imaging of normal and diseased murine brains following a fructose clearing treatment. This technique potentially enables rapid, 3-dimensional evaluation of biological tissues at axial and lateral resolutions comparable to histopathology.

Electrical and optical properties of binary CNx nanocone arrays synthesized by plasma-assisted reaction deposition.

PubMed

Liu, Xujun; Guan, Leilei; Fu, Xiaoniu; Zhao, Yu; Wu, Jiada; Xu, Ning

2014-03-21

Light-absorbing and electrically conductive binary CNx nanocone (CNNC) arrays have been fabricated using a glow discharge plasma-assisted reaction deposition method. The intact CNNCs with amorphous structure and central nickel-filled pipelines could be vertically and neatly grown on nickel-covered substrates according to the catalyst-leading mode. The morphologies and composition of the as-grown CNNC arrays can be well controlled by regulating the methane/nitrogen mixture inlet ratio, and their optical absorption and resistivity strongly depend on their morphologies and composition. Beside large specific surface area, the as-grown CNNC arrays demonstrate high wideband absorption, good conduction, and nice wettability to polymer absorbers.

Optical properties and surface morphology studies of palladium contacts on mercuric iodide single crystals

NASA Astrophysics Data System (ADS)

George, M. A.; Azoulay, M.; Burger, A.; Biao, Y.; Silberman, E.; Nason, D.

1993-04-01

Palladium is chemically suitable for electric contacts on mercuric iodide detectors for photon and nuclear radiation detection, so the understanding of palladium contacts is important for fundamental and practical scientific purposes. A study has been conducted on the surface morphology of evaporated contacts using atomic force microscopy (AFM) and optical transmission and reflection. Evaporated palladium coatings are typically nonuniform and may deposit selectively on mercuric iodide surface defects. Reflection measurements show that coating thickness and surface treatment affect intensity, position, and shape of a reflected peak characteristic of the mercuric iodide structure. Results indicate that the band gap energy in the surface of the mercuric iodide is lowered by palladium contacts.

In situ optical measurements of bacterial endospore breakdown in a shock tube

NASA Astrophysics Data System (ADS)

McCartt, A. D.; Gates, S.; Lappas, P.; Jeffries, J. B.; Hanson, R. K.

2012-03-01

The interaction of endospore-laden bioaerosols and shock waves is monitored with a combination of laser absorption and scattering. Tests are performed in the Stanford aerosol shock tube for post-shock temperatures ranging from 400-1100 K. In situ laser measurements at 266 and 665 nm provide a real-time monitor of endospore morphology. Scatter of visible light measures the integrity of endospore structure, while absorption of UV light provides a monitor of biochemicals released by endospore rupture. For post-shock temperatures greater than 750 K endospore morphological breakdown is observed. A simple theoretical model is employed to quantify the optical measurements, and mechanisms leading to the observed data are discussed.

Quantitative assessment of biophotonic imaging system performance with phantoms fabricated by rapid prototyping

NASA Astrophysics Data System (ADS)

Wang, Jianting; Coburn, James; Woolsey, Nicholas; Liang, Chia-Pin; Ramella-Roman, Jessica; Chen, Yu; Pfefer, Joshua

2014-03-01

In biophotonic imaging, turbid phantoms that are low-cost, biologically-relevant, and durable are desired for standardized performance assessment. Such phantoms often contain inclusions of varying depths and sizes in order to quantify key image quality characteristics such as penetration depth, sensitivity and contrast detectability. The emerging technique of rapid prototyping with three-dimensional (3D) printers provides a potentially revolutionary way to fabricate these structures. Towards this goal, we have characterized the optical properties and morphology of phantoms fabricated by two 3D printing approaches: thermosoftening and photopolymerization. Material optical properties were measured by spectrophotometry while the morphology of phantoms incorporating 0.2-1.0 mm diameter channels was studied by μCT, optical coherence tomography (OCT) and optical microscopy. A near-infrared absorbing dye and nanorods at several concentrations were injected into channels to evaluate detectability with a near-infrared hyperspectral reflectance imaging (HRI) system (650-1100 nm). Phantoms exhibited biologically-relevant scattering and low absorption across visible and near-infrared wavelengths. Although limitations in resolution were noted, channels with diameters of 0.4 mm or more could be reliably fabricated. The most significant problem noted was the porosity of phantoms generated with the thermosoftening-based printer. The aforementioned three imaging methods provided a valuable mix of insights into phantom morphology and may also be useful for detailed structural inspection of medical devices fabricated by rapid prototyping, such as customized implants. Overall, our findings indicate that 3D printing has significant potential as a method for fabricating well-characterized, standard phantoms for medical imaging modalities such as HRI.

Morphological-transformation-based technique of edge detection and skeletonization of an image using a single spatial light modulator

NASA Astrophysics Data System (ADS)

Munshi, Soumika; Datta, A. K.

2003-03-01

A technique of optically detecting the edge and skeleton of an image by defining shift operations for morphological transformation is described. A (2 × 2) source array, which acts as the structuring element of morphological operations, casts four angularly shifted optical projections of the input image. The resulting dilated image, when superimposed with the complementary input image, produces the edge image. For skeletonization, the source array casts four partially overlapped output images of the inverted input image, which is negated, and the resultant image is recorded in a CCD camera. This overlapped eroded image is again eroded and then dilated, producing an opened image. The difference between the eroded and opened image is then computed, resulting in a thinner image. This procedure of obtaining a thinned image is iterated until the difference image becomes zero, maintaining the connectivity conditions. The technique has been optically implemented using a single spatial modulator and has the advantage of single-instruction parallel processing of the image. The techniques have been tested both for binary and grey images.

Super-resolution optical microscopy resolves network morphology of smart colloidal microgels.

PubMed

Bergmann, Stephan; Wrede, Oliver; Huser, Thomas; Hellweg, Thomas

2018-02-14

We present a new method to resolve the network morphology of colloidal particles in an aqueous environment via super-resolution microscopy. By localization of freely diffusing fluorophores inside the particle network we can resolve the three dimensional structure of one species of colloidal particles (thermoresponsive microgels) without altering their chemical composition through copolymerization with fluorescent monomers. Our approach utilizes the interaction of the fluorescent dye rhodamine 6G with the polymer network to achieve an indirect labeling. We calculate the 3D structure from the 2D images and compare the structure to previously published models for the microgel morphology, e.g. the fuzzy sphere model. To describe the differences in the data an extension of this model is suggested. Our method enables the tailor-made fabrication of colloidal particles which are used in various applications, such as paints or cosmetics, and are promising candidates for drug delivery, smart surface coatings, and nanocatalysis. With the precise knowledge of the particle morphology an understanding of the underlying structure-property relationships for various colloidal systems is possible.

Wavelet analysis of biological tissue's Mueller-matrix images

NASA Astrophysics Data System (ADS)

Tomka, Yu. Ya.

2008-05-01

The interrelations between statistics of the 1st-4th orders of the ensemble of Mueller-matrix images and geometric structure of birefringent architectonic nets of different morphological structure have been analyzed. The sensitivity of asymmetry and excess of statistic distributions of matrix elements Cik to changing of orientation structure of optically anisotropic protein fibrils of physiologically normal and pathologically changed biological tissues architectonics has been shown.

Synthesis and Properties of Iron Oxide Particles Prepared by Hidrothermal Method

NASA Astrophysics Data System (ADS)

Saragi, T.; Santika, A. S.; Permana, B.; Syakir, N.; Kartawidjaja, M.; Risdiana

2017-05-01

Iron oxide of hematite (α-Fe2O3) has been successfully synthesized by hydrothermal method. The starting materials were Fe(NO3)3.9H2O, 2-methoxyethanol, diethanolamine and n-hexane. The optical, morphology and crystal structure were measured by UV-VIS, TEM and XRD, respectively. From UV-VIS measurement, it was found that the band-gap of sample was 4.17 eV. The morphology of particle was plate-like form. The sample which sintered at 1100°C has high quality crystal with hexagonal structure of α-Fe2O3 phase.

Tuning the morphology of metastable MnS films by simple chemical bath deposition technique

NASA Astrophysics Data System (ADS)

Dhandayuthapani, T.; Girish, M.; Sivakumar, R.; Sanjeeviraja, C.; Gopalakrishnan, R.

2015-10-01

In the present investigation, we have prepared the spherical particles, almond-like, and cauliflower-like morphological structures of metastable MnS films on glass substrate by chemical bath deposition technique at low temperature without using any complexing or chelating agent. The morphological change of MnS films with molar ratio may be due to the oriented aggregation of adjacent particles. The compositional purity of deposited film was confirmed by the EDAX study. X-ray diffraction and micro-Raman studies confirm the sulfur source concentration induced enhancement in the crystallization of films with metastable MnS phase (zinc-blende β-MnS, and wurtzite γ-MnS). The shift in PL emission peak with molar ratio may be due to the change in optical energy band gap of the MnS, which was further confirmed by the optical absorbance study. The paramagnetic behavior of the sample was confirmed by the M-H plot.

Structural, optical and morphological studies of Cd2+ doping in CH3NH3PbI3 perovskite semiconductor at Pb2+ site for photovoltaic applications

NASA Astrophysics Data System (ADS)

Parrey, Khursheed; Warish, Mohd.; Devi, Nisha; Niazi, A.; Aziz, A.; Ansari, S. G.

2018-05-01

Doping of semiconductors in a controlled mannner have paramount technological importance as far as the optical and electronic properties of the devices are concerned. Hybrid organic-inorganic perovskites (HOPs) as intrinsic semiconductors have sensational properties required for both the solar photovoltaics and perovskite light emitting diodes. However, undoped and complexity in the dpoing process of HOPs have limited their exploitation in the field of elcronics. In this papper we present the synthesis of HOP semiconductor (CH3NH3PbI3) doped in Pb2+ position by Cd2+. We studied the effect of the incorporation of Cd2+ into the crystalline structure and analysed the changes in the properties like crystal structure, optical absorption and the surface morphology. The structure of HOPs confirmed by X-ray diffraction analysis is tetragonal perovskite type. It can be found that the crystallinity of the samples was enhanced with the doping concentration as the intensity of diffraction peaks were observed to increase with doping. The absorption spectra as obtained from UV-Visible spectrophotometry and Tauc plot analysis indicated that the band gap observed (1.73 eV) is direct type and gets reduced to 1.67 eV with the doping concentration. The red shift may be due to the increase in the size of nanocrystalline material with doping.

Evaluation of the structural, optical and electrical properties of AZO thin films prepared by chemical bath deposition for optoelectronics

NASA Astrophysics Data System (ADS)

Kumar, K. Deva Arun; Valanarasu, S.; Rosario, S. Rex; Ganesh, V.; Shkir, Mohd.; Sreelatha, C. J.; AlFaify, S.

2018-04-01

Aluminum doped zinc oxide (AZO) thin films for electrode applications were deposited on glass substrates using chemical bath deposition (CBD) method. The influence of deposition time on the structural, morphological, and opto-electrical properties of AZO films were investigated. Structural studies confirmed that all the deposited films were hexagonal wurtzite structure with polycrystalline nature and exhibited (002) preferential orientation. There is no other impurity phases were detected for different deposition time. Surface morphological images shows the spherically shaped grains are uniformly arranged on to the entire film surface. The EDS spectrum confirms the presence of Zn, O and Al elements in deposited AZO film. The observed optical transmittance is high (87%) in the visible region, and the calculated band gap value is 3.27 eV. In this study, the transmittance value is decreased with increasing deposition time. The room temperature PL spectrum exposed that AZO thin film deposited at (60 min) has good optical quality with less defect density. The minimum electrical resistivity and maximum carrier concentration values were observed as 8.53 × 10-3(Ω cm) and 3.53 × 1018 cm-3 for 60 min deposited film, respectively. The obtained figure of merit (ϕ) value 3.05 × 10-3(Ω/sq)- 1 is suggested for an optoelectronic device.

Polycarbonate-Based Blends for Optical Non-linear Applications.

PubMed

Stanculescu, F; Stanculescu, A

2016-12-01

This paper presents some investigations on the optical and morphological properties of the polymer (matrix):monomer (inclusion) composite materials obtained from blends of bisphenol A polycarbonate and amidic monomers. For the preparation of the composite films, we have selected monomers characterised by a maleamic acid structure and synthesised them starting from maleic anhydride and aniline derivatives with -COOH, -NO2, -N(C2H5)2 functional groups attached to the benzene ring. The composite films have been deposited by spin coating using a mixture of two solutions, one containing the matrix and the other the inclusion, both components of the composite system being dissolved in the same solvent. The optical transmission and photoluminescence properties of the composite films have been investigated in correlation with the morphology of the films. The scanning electron microscopy and atomic force microscopy have revealed a non-uniform morphology characterised by the development of two distinct phases. We have also investigated the generation of some optical non-linear (ONL) phenomena in these composite systems. The composite films containing as inclusions monomers characterised by the presence of one -COOH or two -NO2 substituent groups to the aromatic nucleus have shown the most intense second-harmonic generation (SHG). The second-order optical non-linear coefficients have been evaluated for these films, and the effect of the laser power on the ONL behaviour of these materials has also been emphasised.

Polycarbonate-Based Blends for Optical Non-linear Applications

NASA Astrophysics Data System (ADS)

Stanculescu, F.; Stanculescu, A.

2016-02-01

This paper presents some investigations on the optical and morphological properties of the polymer (matrix):monomer (inclusion) composite materials obtained from blends of bisphenol A polycarbonate and amidic monomers. For the preparation of the composite films, we have selected monomers characterised by a maleamic acid structure and synthesised them starting from maleic anhydride and aniline derivatives with -COOH, -NO2, -N(C2H5)2 functional groups attached to the benzene ring. The composite films have been deposited by spin coating using a mixture of two solutions, one containing the matrix and the other the inclusion, both components of the composite system being dissolved in the same solvent. The optical transmission and photoluminescence properties of the composite films have been investigated in correlation with the morphology of the films. The scanning electron microscopy and atomic force microscopy have revealed a non-uniform morphology characterised by the development of two distinct phases. We have also investigated the generation of some optical non-linear (ONL) phenomena in these composite systems. The composite films containing as inclusions monomers characterised by the presence of one -COOH or two -NO2 substituent groups to the aromatic nucleus have shown the most intense second-harmonic generation (SHG). The second-order optical non-linear coefficients have been evaluated for these films, and the effect of the laser power on the ONL behaviour of these materials has also been emphasised.

Multiscale sensorless adaptive optics OCT angiography system for in vivo human retinal imaging.

PubMed

Ju, Myeong Jin; Heisler, Morgan; Wahl, Daniel; Jian, Yifan; Sarunic, Marinko V

2017-11-01

We present a multiscale sensorless adaptive optics (SAO) OCT system capable of imaging retinal structure and vasculature with various fields-of-view (FOV) and resolutions. Using a single deformable mirror and exploiting the polarization properties of light, the SAO-OCT-A was implemented in a compact and easy to operate system. With the ability to adjust the beam diameter at the pupil, retinal imaging was demonstrated at two different numerical apertures with the same system. The general morphological structure and retinal vasculature could be observed with a few tens of micrometer-scale lateral resolution with conventional OCT and OCT-A scanning protocols with a 1.7-mm-diameter beam incident at the pupil and a large FOV (15 deg× 15 deg). Changing the system to a higher numerical aperture with a 5.0-mm-diameter beam incident at the pupil and the SAO aberration correction, the FOV was reduced to 3 deg× 3 deg for fine detailed imaging of morphological structure and microvasculature such as the photoreceptor mosaic and capillaries. Multiscale functional SAO-OCT imaging was performed on four healthy subjects, demonstrating its functionality and potential for clinical utility. (2017) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE).

Study of nanoparticles TiO{sub 2} thin films on p-type silicon substrate using different alcoholic solvents

DOE Office of Scientific and Technical Information (OSTI.GOV)

Muaz, A. K. M.; Ruslinda, A. R.; Ayub, R. M.

2016-07-06

In this paper, sol-gel method spin coating technique is adopted to prepare nanoparticles titanium dioxide (TiO{sub 2}) thin films. The prepared TiO{sub 2} sol was synthesized using titanium butoxide act as a precursor and subjected to deposited on the p-type silicon oxide (p-SiO{sub 2}) and glass slide substrates under room temperature. The effect of different alcoholic solvents of methanol and ethanol on the structural, morphological, optical and electrical properties were systematically investigated. The coated TiO{sub 2} thin films were annealed in furnace at 773 K for 1 h. The structural properties of the TiO{sub 2} films were examined with X-raymore » Diffraction (XRD). From the XRD analysis, both solvents showing good crystallinity with anatase phase were the predominant structure. Atomic Force Microscopy (AFM) was employed to study the morphological of the thin films. The optical properties were investigated by Ultraviolet-visible (UV-Vis) spectroscopy were found that ethanol as a solvent give a higher optical transmittance if compare to the methanol solvent. The electrical properties of the nanoparticles TiO{sub 2} thin films were measured using two-point-probe technique.« less

Structural, Optical and Electrical Properties of ITO Thin Films

NASA Astrophysics Data System (ADS)

Sofi, A. H.; Shah, M. A.; Asokan, K.

2018-02-01

Transparent and conductive thin films of indium tin oxide were fabricated on glass substrates by the thermal evaporation technique. Tin doped indium ingots with low tin content were evaporated in vacuum (1.33 × 10-7 kpa) followed by an oxidation for 15 min in the atmosphere in the temperature range of 600-700°C. The structure and phase purity, surface morphology, optical and electrical properties of thin films were studied by x-ray diffractometry and Raman spectroscopy, scanning electron microcopy and atomic force microscopy, UV-visible spectrometry and Hall measurements in the van der Pauw configuration. The x-ray diffraction study showed the formation of the cubical phase of polycrystalline thin films. The morphological analysis showed the formation of ginger like structures and the energy dispersive x-ray spectrum confirmed the presence of indium (In), tin (Sn) and oxygen (O) elements. Hall measurements confirmed n-type conductivity of films with low electrical resistivity ( ρ) ˜ 10-3 Ω cm and high carrier concentration ( n) ˜ 1020 cm-3. For prevalent scattering mechanisms in the films, experimental data was analyzed by calculating a mean free path ( L) using a highly degenerate electron gas model. Furthermore, to investigate the performance of the deposited films as a transparent conductive material, the optical figure of merit was obtained for all the samples.

Effect of reaction atmosphere on structural and optical properties of hexagonal molybdenum oxide (h-MoO{sub 3})

DOE Office of Scientific and Technical Information (OSTI.GOV)

Doss, V. Arumai; Chithambararaj, A.; Bose, A. Chandra, E-mail: acbose@nitt.edu

2016-05-23

The present work aims to synthesize single phase h-MoO{sub 3} nanocrytals by chemical precipitation method exposed under different reaction atmospheres. The reaction atmosphere have been successfully tuned as air, nitrogen and argon and studied its effects on structural, functional, morphology and optical properties by using X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectroscopy and diffuse reflectance spectroscopy (DRS) measurements. The XRD result indicates that the sample exhibits characteristic hexagonal phase of MoO{sub 3}. The crystallite size is estimated by well known Scherrer’s method. The crystallite size is relative small in the case of sample prepared atmore » argon atmosphere. The functional groups such as Mo-O, N-H and O-H are identified from FT-IR spectroscopy. The particle exhibits rod like morphology with perfect hexagonal cross-section. The optical absorption observed at 420-450 nm corresponds to fundamental optical absorption by h-MoO{sub 3}. The band gap values are estimated using Kublka-Munk (K-M) function and found to be 2. 87 eV, 2.93 eV and 2.97 eV for samples synthesized under air, nitrogen and argon, respectively.« less

Preparation and characterization of nanocrystalline CuO powders with the different surfactants and complexing agent mediated precipitation method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rajendran, V.; Gajendiran, J., E-mail: gaja.nanotech@gmail.com

2014-08-15

Highlights: • CuO nanostructures by surfactants mediated method. • Structural and optical properties of CuO nanostructures changes under the effect of surface modifier. • Citric acid assisted is the best, in terms of size, morphology and optical properties than that of CTAB, SDS and PEG-400. - Abstract: Nanostructures of copper oxide (CuO) was synthesized into crystallite sized ranging from 20 to 50 nm in the presence of different surfactants, and complex agent such as cityl tri methyl ammonium bromide (CTAB), sodium do decyl sulfate (SDS), poly ethylene glycol (PEG-400) and citric acid via a precipitation route. Variations in several parametersmore » and their effects on the structural and optical properties of CuO nanostructures (crystallite size, morphology and band gap) were investigated by XRD, FTIR, SEM and UV analysis. The UV–visible absorption spectra of the different surfactants and complexing agent assisted CuO nanostructures indicates that the estimated optical band gap energy value (1.94–1.98 eV) is higher than that of the bulk CuO value (1.4 eV), which is attributed to the quantum confinement effect. The formation mechanism of different surfactants and complexing agent assisted CuO nanostructures is also proposed.« less

Recognition-Mediated Assembly of Quantum Dot Polymer Conjugates with Controlled Morphology

PubMed Central

Nandwana, Vikas; Subramani, Chandramouleeswaran; Eymur, Serkan; Yeh, Yi-Cheun; Tonga, Gulen Yesilbag; Tonga, Murat; Jeong, Youngdo; Yang, Boqian; Barnes, Michael D.; Cooke, Graeme; Rotello, Vincent M.

2011-01-01

We have demonstrated a polymer mediated “bricks and mortar” method for the self-assembly of quantum dots (QDs). This strategy allows QDs to self-assemble into structured aggregates using complementary three-point hydrogen bonding. The resulting nanocomposites have distinct morphologies and inter-particle distances based on the ratio between QDs and polymer. Time resolved photoluminescence measurements showed that the optical properties of the QDs were retained after self-assembly. PMID:22016664

Third order nonlinear optical properties of Mn doped CeO2 nanostructures

NASA Astrophysics Data System (ADS)

Mani Rahulan, K.; Angeline Little Flower, N.; Annie Sujatha, R.; Mohana Priya, P.; Gopalakrishnan, C.

2018-05-01

Mn doped CeO2 nanoparticles with different ratios of Mn were synthesized by hydrothermal method and their structural properties were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and Scanning electron microscopy (SEM). XRD patterns revealed that the peaks are highly crystalline structure with no segregation of Mn. The surface morphology from SEM reveals that particle size decreases with increase in Mn concentration. Nonlinear optical studies of the samples were measured by single-beam open aperture Z-scan technique using 5 ns laser pulses at 532 nm. The measured optical nonlinearity of all the samples exhibit typical third order nonlinear optical behavior including two-photon absorption (2 PA) and reverse saturable absorption (RSA). The experimental results show that the presence of RSA in these nanoparticles makes them a promising material for the fabrication of optical limiting devices. .

A sparsity-based simplification method for segmentation of spectral-domain optical coherence tomography images

NASA Astrophysics Data System (ADS)

Meiniel, William; Gan, Yu; Olivo-Marin, Jean-Christophe; Angelini, Elsa

2017-08-01

Optical coherence tomography (OCT) has emerged as a promising image modality to characterize biological tissues. With axio-lateral resolutions at the micron-level, OCT images provide detailed morphological information and enable applications such as optical biopsy and virtual histology for clinical needs. Image enhancement is typically required for morphological segmentation, to improve boundary localization, rather than enrich detailed tissue information. We propose to formulate image enhancement as an image simplification task such that tissue layers are smoothed while contours are enhanced. For this purpose, we exploit a Total Variation sparsity-based image reconstruction, inspired by the Compressed Sensing (CS) theory, but specialized for images with structures arranged in layers. We demonstrate the potential of our approach on OCT human heart and retinal images for layers segmentation. We also compare our image enhancement capabilities to the state-of-the-art denoising techniques.

Extraction of cellulose nanofibrils from dry softwood pulp using high shear homogenization.

PubMed

Zhao, Jiangqi; Zhang, Wei; Zhang, Xiaodan; Zhang, Xinxing; Lu, Canhui; Deng, Yulin

2013-09-12

The objective of this study was to extract cellulose nanofibrils (CNFs) from dry softwood pulp through a simple and environmentally friendly physical method of refining pretreatment coupled with high shear homogenization. An optical microscopy (OM) clearly showed the morphological development from the cellulose fibers to CNFs under repeated shear forces. The morphology, structure and properties of the obtained CNFs were comprehensively investigated using scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transformed infrared (FTIR) spectra, X-ray diffraction (XRD) and thermogravimetric (TG) analysis. The results indicated that the CNFs had diameters mainly ranged from 16 to 28nm. Compared with the pulp fibers, the CNFs exhibited a slightly higher crystallinity and a lower thermal stability. Moreover, a novel nanopaper with high optical transparency was prepared from the obtained CNFs, and a possible mechanism for the high optical transparency was discussed. Copyright © 2013 Elsevier Ltd. All rights reserved.

Surface Modification of Carbon Fiber Polymer Composites after Laser Structuring

NASA Astrophysics Data System (ADS)

Sabau, Adrian S.; Chen, Jian; Jones, Jonaaron F.; Hackett, Alexandra; Jellison, Gerald D.; Daniel, Claus; Warren, David; Rehkopf, Jackie D.

The increasing use of Carbon Fiber-reinforced Polymer matrix Composites (CFPC) as a lightweight material in automotive and aerospace industries requires the control of surface morphology. In this study, the composites surface was prepared by ablating the resin on the top fiber layer of the composite using an Nd:YAG laser. The CFPC specimens with T700S carbon fiber and Prepreg — T83 resin (epoxy) were supplied by Plasan Carbon Composites, Inc. as 4 ply thick, 0/90° plaques. The effect of laser fluence, scanning speed, and wavelength was investigated on the removal rate of the resin without an excessive damage of the fibers. In addition, resin ablation due to the power variation created by a laser interference technique is presented. Optical property measurements, optical micrographs, 3D imaging, and high-resolution optical profiler images were used to study the effect of the laser processing on surface morphology.

CRISTAPRESS: an optical cell for structure development in high-pressure crystallization.

PubMed

Boyer, S A E; Fournier, F E J; Gandin, Ch-A; Haudin, J-M

2014-01-01

An original optical high-pressure cell, named CRISTAPRESS, has been especially designed to investigate phase transitions of complex liquids, i.e., polymers, polymer blends, nano-composites, etc. The design of the cell is based on the optical properties of morphological entities through in situ light depolarizing microscopic observations. Pressure up to 200 MPa with a fine temperature control up to 300 °C can be applied. A striking advantage of this cell is the possibility to select the pressure transmitting medium that can be water, silicone oil, a fluid in the supercritical state, etc. The potential of the novel technique was demonstrated by carrying out time-resolved measurements during polymer crystallization induced by water pressure. These preliminary experimental investigations permit to discriminate the role of the barometric and thermal histories on the kinetics of polymer growth, as well as on the subsequent morphologies. It should lead to new reliable crystallization kinetics models.

Crystal Growth and Dissolution of Methylammonium Lead Iodide Perovskite in Sequential Deposition: Correlation between Morphology Evolution and Photovoltaic Performance.

PubMed

Hsieh, Tsung-Yu; Huang, Chi-Kai; Su, Tzu-Sen; Hong, Cheng-You; Wei, Tzu-Chien

2017-03-15

Crystal morphology and structure are important for improving the organic-inorganic lead halide perovskite semiconductor property in optoelectronic, electronic, and photovoltaic devices. In particular, crystal growth and dissolution are two major phenomena in determining the morphology of methylammonium lead iodide perovskite in the sequential deposition method for fabricating a perovskite solar cell. In this report, the effect of immersion time in the second step, i.e., methlyammonium iodide immersion in the morphological, structural, optical, and photovoltaic evolution, is extensively investigated. Supported by experimental evidence, a five-staged, time-dependent evolution of the morphology of methylammonium lead iodide perovskite crystals is established and is well connected to the photovoltaic performance. This result is beneficial for engineering optimal time for methylammonium iodide immersion and converging the solar cell performance in the sequential deposition route. Meanwhile, our result suggests that large, well-faceted methylammonium lead iodide perovskite single crystal may be incubated by solution process. This offers a low cost route for synthesizing perovskite single crystal.

Investigating the transverse optical structure of spider silk micro-fibers using quantitative optical microscopy

NASA Astrophysics Data System (ADS)

Little, Douglas J.; Kane, Deb M.

2017-01-01

The transverse optical structure of two orb-weaver (family Araneidae) spider dragline silks was investigated using a variant of the inverse-scattering technique. Immersing the silks in a closely refractive index-matched liquid, the minimum achievable image contrast was greater than expected for an optically homogeneous silk, given what is currently known about the optical absorption of these silks. This "excess contrast" indicated the presence of transverse optical structure within the spider silk. Applying electromagnetic scattering theory to a transparent double cylinder, the minimum achievable irradiance contrast for the Plebs eburnus and Argiope keyserlingi dragline silks was determined to be consistent with step index refractive index contrasts of 1-4×10-4 and 6-7×10-4, respectively, supposing outer-layer thicknesses consistent with previous TEM studies (50 nm and 100 nm, respectively). The possibility of graded index refractive index contrasts within the spider silks is also discussed. This is the strongest evidence, to date, that there is a refractive index contrast associated with the layered morphology of spider silks and/or variation of proportion of nanocrystalline components within the spider silk structure. The method is more generally applicable to optical micro-fibers, including those with refractive index variations on a sub-wavelength scale.

Toward an Understanding of Divergent Compound Eye Development in Drones and Workers of the Honeybee (Apis mellifera L.): A Correlative Analysis of Morphology and Gene Expression.

PubMed

Marco Antonio, David S; Hartfelder, Klaus

2017-01-01

Eye development in insects is best understood in Drosophila melanogaster, but little is known for other holometabolous insects. Combining a morphological with a gene expression analysis, we investigated eye development in the honeybee, putting emphasis on the sex-specific differences in eye size. Optic lobe development starts from an optic lobe anlage in the larval brain, which sequentially gives rise to the lobula, medulla, and lamina. The lamina differentiates in the last larval instar, when it receives optic nerve projections from the developing retina. The expression analysis focused on seven genes important for Drosophila eye development: eyes absent, sine oculis, embryonic lethal abnormal vision, minibrain, small optic lobes, epidermal growth factor receptor, and roughest. All except small optic lobes were more highly expressed in third-instar drone larvae, but then, in the fourth and fifth instar, their expression was sex-specifically modulated, showing shifts in temporal dynamics. The clearest differences were seen for small optic lobes, which is highly expressed in the developing eye of workers, and minibrain and roughest, which showed a strong expression peak coinciding with retina differentiation. A microarray analysis for optic lobe/retina complexes revealed the differential expression of several metabolism-related genes, as well as of two micro-RNAs. While we could not see major morphological differences in the developing eye structures before the pupal stage, the expression differences observed for the seven candidate genes and in the transcriptional microarray profiles indicate that molecular signatures underlying sex-specific optic lobe and retina development become established throughout the larval stages. © 2016 Wiley Periodicals, Inc.

Three-dimensional multifunctional optical coherence tomography for skin imaging

NASA Astrophysics Data System (ADS)

Li, En; Makita, Shuichi; Hong, Young-Joo; Kasaragod, Deepa; Sasaoka, Tomoko; Yamanari, Masahiro; Sugiyama, Satoshi; Yasuno, Yoshiaki

2016-02-01

Optical coherence tomography (OCT) visualizes cross-sectional microstructures of biological tissues. Recent developments of multifunctional OCT (MF-OCT) provides multiple optical contrasts which can reveal currently unknown tissue properties. In this contribution we demonstrate multifunctional OCT specially designed for dermatological investigation. And by utilizing it to measure four different body parts of in vivo human skin, three-dimensional scattering OCT, OCT angiography, polarization uniformity tomography, and local birefringence tomography images were obtained by a single scan. They respectively contrast the structure and morphology, vasculature, melanin content and collagen traits of the tissue.

Zincblende to Wurtzite phase shift of CdSe thin films prepared by electrochemical deposition

NASA Astrophysics Data System (ADS)

Bai, Rekha; Chaudhary, Sujeet; Pandya, Dinesh K.

2018-04-01

Cadmium selenide (CdSe) nanostructured thin films have been deposited on conducting glass substrates by potentiostatic electrochemical deposition (ECD) technique. The effect of electrolyte bath pH on the structural, morphological and optical properties of CdSe films has been investigated. Crystal structure of these films is characterized by X-ray diffraction and Raman spectroscopy which reveal polycrystalline nature of CdSe films exhibiting phase shift from zincblende to wurtzite structure with increase in bath pH. Optical studies reveal that the CdSe thin films have good absorbance in visible spectral region and they possess direct optical band gap which increases from 1.68 to 1.97 eV with increase in bath pH. The results suggest CdSe is an efficient absorber material for next generation solar cells.

Influence of bias voltage on structural and optical properties of TiN{sub x} thin films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Singh, Omveer, E-mail: poonia.omveer@gmail.com; Dahiya, Raj P.; Deenbandhu Chhotu Ram University of Science and Technology, Murthal – 131039

In the present work, Ti thin films were deposited on Si substrate using DC sputtering technique. Indigenous hot cathode arc discharge plasma system was used for nitriding over these samples, where the plasma parameters and work piece can be controlled independently. A mixture of H{sub 2} and N{sub 2} gases (in the ratio of 80:20) was supplied into the plasma chamber. The effect of bias voltage on the crystal structure, morphology and optical properties was investigated by employing various physical techniques such as X-ray Diffraction, Atomic Force Microscopy and UV-Vis spectrometry. It was found that bias voltage affects largely themore » crystal structure and band gap which in turn is responsible for the modifications in optical properties of the deposited films.« less

Bile salt incorporated polypyrrole thin film for ethanol sensing.

PubMed

Sharma, Partha P D; Sarkar, D

2015-04-01

Polypyrrole (PPy)-bile salt composite was used for sensing ethanol vapor. PPy was synthesized by interface polymerization for subsequent fabrication of thin film of its composite with bile salt, by in-situ co-dispersion method and then exposed to ethanol vapour. Sensing was visualized through changes in morphological, structural and optical characterizations. The ethanol exposed film showed larger agglomeration as revealed in its surface morphology on scanning electron microscope (SEM) and greater crystallinity as seen through X-Ray diffraction (XRD). Fourier transform infra red (FTIR) and nuclear magnetic resonance spectroscopy (NMR) of the ethanol incorporated film also gave signature of the presence of bile salt and alcohol. Alcohol incorporation pattern resulted in increase in electrical conductance from 7.08539 x 10(-5) mA/V to 8.0356 x 10(-5) mA/V, as determined from current voltage characterizations. Average molecular weight (M(n)) obtained from gel permeation chromatography changed from 6160 to 10300 on ethanol intake. Photoluminescence (PL) intensity was quenched and the PL peak shifted from 430 to 409 on ethanol exposure. Changes in morphological, structural, optical and electrical properties of the composite on ethanol exposure showed its prospective application for sensing ethanol.

Structural Color Model Based on Surface Morphology of MORPHO Butterfly Wing Scale

NASA Astrophysics Data System (ADS)

Huang, Zhongjia; Cai, Congcong; Wang, Gang; Zhang, Hui; Huttula, Marko; Cao, Wei

2016-05-01

Color production through structural coloration is created by micrometer and sub-micrometer surface textures which interfere with visible light. The shiny blue of morpho menelaus is a typical example of structural coloring. Modified from morphology of the morpho scale, a structure of regular windows with two side offsets was constructed on glass substrates. Optical properties of the bioinspired structure were studied through numerical simulations of light scattering. Results show that the structure can generate monochromatic light scattering. Wavelength of scattered light is tunable via changing the spacing between window shelves. Compared to original butterfly model, the modified one possesses larger illumination scopes in azimuthal distributions despite being less in polar directions. Present bionic structure is periodically repeated and is easy to fabricate. It is hoped that the computational materials design work can inspire future experimental realizations of such a structure in photonics applications.

Nanostructured sapphire optical fiber for sensing in harsh environments

NASA Astrophysics Data System (ADS)

Chen, Hui; Liu, Kai; Ma, Yiwei; Tian, Fei; Du, Henry

2017-05-01

We describe an innovative and scalable strategy of transforming a commercial unclad sapphire optical fiber to an allalumina nanostructured sapphire optical fiber (NSOF) that overcomes decades-long challenges faced in the field of sapphire fiber optics. The strategy entails fiber coating with metal Al followed by subsequent anodization to form anodized alumina oxide (AAO) cladding of highly organized pore channel structure. We show that Ag nanoparticles entrapped in AAO show excellent structural and morphological stability and less susceptibility to oxidation for potential high-temperature surface-enhanced Raman Scattering (SERS). We reveal, with aid of numerical simulations, that the AAO cladding greatly increases the evanescent-field overlap both in power and extent and that lower porosity of AAO results in higher evanescent-field overlap. This work has opened the door to new sapphire fiber-based sensor design and sensor architecture.

Analysis of structural and optical properties of annealed fullerene thin films

NASA Astrophysics Data System (ADS)

El-Nahass, M. M.; Ali, H. A. M.; Gadallah, A.-S.; Atta Khedr, M.; Afify, H. A.

2015-08-01

Fullerene thin films were thermally deposited onto different substrates. The films annealed at 523 K for 10 h. X-ray diffraction technique was used to examine the structure of the films. The morphology of films was examined by field emission scanning electron microscopy. Fourier transform infrared spectra were recorded in wavenumber range 400-2000 cm-1. The optical characteristics were analyzed using UV- Vis-NIR spectrophotometric measurements in the spectral range 200-2500 nm. The refractive index and extinction coefficient were determined. Some dispersion parameters were calculated such as single oscillator energy, dispersion energy, dielectric constant at high frequency and lattice dielectric constant. As well as, the nonlinear optical susceptibility χ(3) and nonlinear refractive index n2 were determined.

Depth elemental characterization of 1D self-aligned TiO2 nanotubes using calibrated radio frequency glow discharge optical emission spectroscopy (GDOES)

NASA Astrophysics Data System (ADS)

Mohajernia, Shiva; Mazare, Anca; Hwang, Imgon; Gaiaschi, Sofia; Chapon, Patrick; Hildebrand, Helga; Schmuki, Patrik

2018-06-01

In this work we study the depth composition of anodic TiO2 nanotube layers. We use elemental depth profiling with Glow Discharge Optical Emission Spectroscopy and calibrate the results of this technique with X-ray photoelectron spectroscopy (XPS) and energy dispersive spectroscopy (EDS). We establish optimized sputtering conditions for nanotubular structures using the pulsed RF mode, which causes minimized structural damage during the depth profiling of the nanotubular structures. This allows to obtain calibrated sputter rates that account for the nanotubular "porous" morphology. Most importantly, sputter-artifact free compositional profiles of these high aspect ratio 3D structures are obtained, as well as, in combination with SEM, elegant depth sectional imaging.

Synthesis of Cu{sub 2}ZnSnS{sub 4} nanoparticles and controlling the morphology with polyethylene glycol

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rawat, Kusum; Department of Electronic Science, University of Delhi South Campus, Delhi 110021; Kim, Hee-Joon

Highlights: • Cu{sub 2}ZnSnS{sub 4} nanoparticles were synthesized by wet chemical technique. • First report on the effect of using polyethylene glycol as a structure directing agent on Cu{sub 2}ZnSnS{sub 4} nanoparticles. • The morphology of Cu{sub 2}ZnSnS{sub 4} nanoparticles changes into nanoflakes and nanorods structures with polyethylene glycol concentration. • Polyethylene glycol assisted Cu{sub 2}ZnSnS{sub 4} nanoparticle film exhibits optical bandgap of 1.5 eV which is suitable for the application in solar cells. - Abstract: Cu{sub 2}ZnSnS{sub 4} nanoparticles were synthesized by wet chemical technique using metal thiourea precursor at 250 °C. The structural and morphological properties of asmore » grown nanoparticles have been characterized by X-ray diffraction, Raman spectroscopy, scanning electron microscopy and transmission electron microscopy. The influence of different concentration of polyethylene glycol as structure directing agent on the morphologies of Cu{sub 2}ZnSnS{sub 4} nanoparticles are investigated on thin films deposited by spin coating technique. The mean crystallite size of the Cu{sub 2}ZnSnS{sub 4} nanoparticles was found to improve with polyethylene glycol concentration. Scanning electron microscopy images of Cu{sub 2}ZnSnS{sub 4} revealed aggregated spherical shaped nanoparticles whereas the polyethylene glycol assisted Cu{sub 2}ZnSnS{sub 4} nanoparticle films show nanoflakes and nanorods structures with increasing concentration of polyethylene glycol. Transmission electron microscopy analysis has also been performed to determine the size and structure of nanorods. UV–vis absorption spectroscopy shows the broad band absorption with optical bandgap of 1.50 eV for polyethylene glycol assisted Cu{sub 2}ZnSnS{sub 4} films.« less

Neural Organization of the Optic Lobe Changes Steadily from Late Embryonic Stage to Adulthood in Cuttlefish Sepia pharaonis

PubMed Central

Liu, Yung-Chieh; Liu, Tsung-Han; Su, Chia-Hao; Chiao, Chuan-Chin

2017-01-01

The optic lobe is the largest structure in the cuttlefish brain. While the general morphology of the optic lobe in adult cuttlefish has been well described, the 3D structure and ontogenetic development of its neural organization have not been characterized. To correlate observed behavioral changes within the brain structure along the development of this animal, optic lobes from the late embryonic stage to adulthood were examined systematically in the present study. The MRI scan revealed that the so called “cell islands” in the medulla of the cephalopod's optic lobe (Young, 1962, 1974) are in fact a contiguous tree-like structure. Quantification of the neural organizational development of optic lobes showed that structural features of the cortex and radial column zone were established earlier than those of the tangential zone during embryonic and post-hatching stages. Within the cell islands, the density of nuclei was decreased while the size of nuclei was increased during the development. Furthermore, the visual processing area in the optic lobe showed a significant variation in lateralization during embryonic and juvenile stages. Our observation of a continuous increase in neural fibers and nucleus size in the tangential zone of the optic lobe from late embryonic stage to adulthood indicates that the neural organization of the optic lobe is modified along the development of cuttlefish. These findings thus support that the ontogenetic change of the optic lobe is responsible for their continuously increased complexity in body patterning and visuomotor behaviors. PMID:28798695

Copper Ion Beam Irradiation-Induced Effects on Structural, Morphological and Optical Properties of Tin Dioxide Nanowires

NASA Astrophysics Data System (ADS)

A. Khan, M.; Qayyum, A.; I., Ahmed; T., Iqbal; A. Khan, A.; Waleed, R.; Mohuddin, B.; Malik, M.

2016-07-01

Not Available Supported by the Department of Physics, the University of AJK, High Tech. Centralized Instrumentation Lab, the University of AJK, Pakistan and the Experimental Physics Division, and the National Center for Physics, Islamabad Pakistan.

Vapor-solid growth of one-dimensional layer-structured gallium sulfide nanostructures.

PubMed

Shen, Guozhen; Chen, Di; Chen, Po-Chiang; Zhou, Chongwu

2009-05-26

Gallium sulfide (GaS) is a wide direct bandgap semiconductor with uniform layered structure used in photoelectric devices, electrical sensors, and nonlinear optical applications. We report here the controlled synthesis of various high-quality one-dimensional GaS nanostructures (thin nanowires, nanobelts, and zigzag nanobelts) as well as other kinds of GaS products (microbelts, hexagonal microplates, and GaS/Ga(2)O(3) heterostructured nanobelts) via a simple vapor-solid method. The morphology and structures of the products can be easily controlled by substrate temperature and evaporation source. Optical properties of GaS thin nanowires and nanobelts were investigated and both show an emission band centered at 580 nm.

Advanced light-scattering materials: Double-textured ZnO:B films grown by LP-MOCVD

NASA Astrophysics Data System (ADS)

Addonizio, M. L.; Spadoni, A.; Antonaia, A.

2013-12-01

Double-textured ZnO:B layers with enhanced optical scattering in both short and long wavelength regions have been successfully fabricated using MOCVD technique through a three step process. Growth of double-textured structures has been induced by wet etching on polycrystalline ZnO surface. Our double-layer structure consists of a first ZnO:B layer wet etched and subsequently used as substrate for a second ZnO:B layer deposition. Polycrystalline ZnO:B layers were etched by utilizing diluted solutions of fluoridic acid (HF), chloridric acid (HCl) and phosphoric acid (H3PO4) and their effect on surface morphology modification was systematically investigated. The morphology of the second deposited ZnO layer strongly depended on the surface properties of the etched ZnO first layer. Growth of cauliflower-like texture was induced by protrusions presence on the HCl etched surface. Optimized double-layer structure shows a cauliflower-like double texture with higher RMS roughness and increased spectral haze values in both short and long wavelength regions, compared to conventional pyramidal-like single texture. Furthermore, this highly scattering structure preserves excellent optical and electrical properties.

Localized Surface Plasmon Resonance in Au Nanoparticles Embedded dc Sputtered ZnO Thin Films.

PubMed

Patra, Anuradha; Balasubrahmaniyam, M; Lahal, Ranjit; Malar, P; Osipowicz, T; Manivannan, A; Kasiviswanathan, S

2015-02-01

The plasmonic behavior of metallic nanoparticles is explicitly dependent on their shape, size and the surrounding dielectric space. This study encompasses the influence of ZnO matrix, morphology of Au nanoparticles (AuNPs) and their organization on the optical behavior of ZnO/AuNPs-ZnO/ZnO/GP structures (GP: glass plate). These structures have been grown by a multiple-step physical process, which includes dc sputtering, thermal evaporation and thermal annealing. Different analytical techniques such as scanning electron microscopy, glancing angle X-ray diffraction, Rutherford backscattering spectrometry and optical absorption have been used to study the structures. In-situ rapid thermal treatment during dc sputtering of ZnO film has been found to induce subtle changes in the morphology of AuNPs, thereby altering the profile of the plasmon band in the absorption spectra. The results have been contrasted with a recent study on the spectral response of dc magnetron sputtered ZnO films embedded with AuNPs. Initial simulation results indicate that AuNPs-ZnO/Au/GP structure reflects/absorbs UV and infrared radiations, and therefore can serve as window coatings.

Synergistic effect of indium and gallium co-doping on the properties of RF sputtered ZnO thin films

NASA Astrophysics Data System (ADS)

Shaheera, M.; Girija, K. G.; Kaur, Manmeet; Geetha, V.; Debnath, A. K.; Karri, Malvika; Thota, Manoj Kumar; Vatsa, R. K.; Muthe, K. P.; Gadkari, S. C.

2018-04-01

ZnO thin films were synthesized using RF magnetron sputtering, with simultaneous incorporation of Indium (In) and Gallium (Ga). The structural, optical, chemical composition and surface morphology of the pure and co-doped (IGZO) thin films were characterized by X-Ray diffraction (XRD), UV-visible spectroscopy, Field Emission Scanning Electron Microscopy (FESEM), and Raman spectroscopy. XRD revealed that these films were oriented along c-axis with hexagonal wurtzite structure. The (002) diffraction peak in the co-doped sample was observed at 33.76° with a slight shift towards lower 2θ values as compared to pure ZnO. The surface morphology of the two thin films was observed to differ. For pure ZnO films, round grains were observed and for IGZO thin films round as well as rod type grains were observed. All thin films synthesized show excellent optical properties with more than 90% transmission in the visible region and band gap of the films is observed to decrease with co-doping. The co doping of In and Ga is therefore expected to provide a broad range optical and physical properties of ZnO thin films for a variety of optoelectronic applications.

Controlling Growth Orientation of Phthalocyanine Films by Electrical Fields

NASA Technical Reports Server (NTRS)

Zhu, S.; Banks, C. E.; Frazier, D. O.; Ila, D.; Muntele, I.; Penn, B. G.; Sharma, A.; Rose, M. Franklin (Technical Monitor)

2001-01-01

Organic Phthalocyanine films have many applications ranging from data storage to various non-linear optical devices whose quality is affected by the growth orientation of Phthalocyanine films. Due to the structural and electrical properties of Phthalocyanine molecules, the film growth orientation depends strongly on the substrate surface states. In this presentation, an electrical field up to 4000 V/cm is introduced during film growth. The Phthalocyanine films are synthesized on quartz substrates using thermal evaporation. An intermediate layer is deposited on some substrates for introducing the electrical field. Scanning electron microscopy, x-ray diffraction, and Fourier transform infrared spectroscopy are used for measuring surface morphology, film structure, and optical properties, respectively. The comparison of Phthalocyanine films grown with and without the electrical field reveals different morphology, film density, and growth orientation, which eventually change optical properties of these films. These results suggest that the growth method in the electrical field can be used to synthesized Phthalocyanine films with a preferred crystal orientation as well as propose an interaction mechanism between the substrate surface and the depositing molecules. The details of growth conditions and of the growth model of how the Phthalocyanine molecules grow in the electrical field will be discussed.

The green hydrothermal synthesis of nanostructured Cu2ZnSnSe4 as solar cell material and study of their structural, optical and morphological properties

NASA Astrophysics Data System (ADS)

Vanalakar, S. A.; Agawane, G. L.; Kamble, A. S.; Patil, P. S.; Kim, J. H.

2017-12-01

Cu2ZnSnSe4 (CZTSe) has attracted intensive attention as an absorber material for the thin-film solar cells due to its high absorption coefficient, direct band gap, low toxicity, and abundance of its constituent elements. In this study nanostructured CZTSe nanoparticles are prepared via green hydrothermal synthesis without using toxic solvents, organic amines, catalysts or noxious chemicals. The structural, optical, and morphological properties of CZTSe nanostructured powder were studied using X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), UV-vis absorption spectroscopy, and transmission electron microscope (TEM) techniques. Raman peaks at 170, 195, and 232 cm-1 confirm the formation of pure phase CZTSe nanostructured particles. In addition, the EDS and XPS results confirm the appropriate chemical purity of the annealed CZTSe nanoparticles. Meanwhile, the TEM analysis showed the presence of phase pure oval like CZTSe particle with size of about 80-140 nm. The UV-Vis-NIR absorption spectra analysis showed that the optical band gap of CZTSe nanostructured particles is about 1.14 eV. This band gap energy is close to the optimum value of a photovoltaic solar cell absorber material.

Effect of different processes and Ti/Zn molar ratios on the structure, morphology, and enhanced photoelectrochemical and photocatalytic performance of Ti3+ self-doped titanium-zinc hybrid oxides

NASA Astrophysics Data System (ADS)

Fu, Rongrong; Wang, Qingyao; Gao, Shanmin; Wang, Zeyan; Huang, Baibiao; Dai, Ying; Lu, Jun

2015-07-01

Ti3+ self-doped titanium-zinc hybrid oxides with different phase compositions and morphologies were successfully synthesized using Zn powder as the reductant and Zn source by a chemical-reduction precipitation method with subsequent thermal treatment. The fabricated Ti3+ self-doped TiO2(A)/TiO2(R), TiO2(A)/TiO2(R)/ZnTiO3, and TiO2(A)/ZnO heterojunctions were characterized by X-ray diffraction, transmission electron microscopy, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, and UV-Vis diffuse reflectance spectroscopy. The effects of various Ti/Zn molar ratios and preparation processes on the structural, morphological, optical, photocurrent and photocatalytic properties of the resultant samples were investigated systematically. Results reveal that Ti3+ self-doping enhances the photoabsorption capability of titanium-zinc hybrid oxides in the visible-light region. Moreover, different processes and Ti/Zn molar ratios play great influences on the structure, morphology, optical, photocurrent and photocatalytic properties of the final products. Ti3+ self-doped titanium-zinc hybrid oxides exhibit excellent photocurrent and photocatalytic activity than pure TiO2 and ZnTiO3 under visible-light irradiation (λ ≥ 400 nm). The most active Ti3+ self-doped titanium-zinc hybrid oxides photoanode presents significantly improved water splitting performance. The synergistic effect between the Ti3+ self-doped and heterojunctions is responsible for the enhanced performance of these materials.

Effect of different processes and Ti/Zn molar ratios on the structure, morphology, and enhanced photoelectrochemical and photocatalytic performance of Ti3+ self-doped titanium–zinc hybrid oxides

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fu, Rongrong; Wang, Qingyao; Gao, shanmin

2015-07-01

Ti3+ self-doped titanium–zinc hybrid oxides with different phase compositions and morphologies were successfully synthesized using Zn powder as the reductant and Zn source by a chemical-reduction precipitation method with subsequent thermal treatment. The fabricated Ti3+ self-doped TiO2(A)/TiO2(R), TiO2(A)/TiO2(R)/ZnTiO3, and TiO2(A)/ZnO heterojunctions were characterized by X-ray diffraction, transmission electron microscopy, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, and UV–Vis diffuse reflectance spectroscopy. The effects of various Ti/Zn molar ratios and preparation processes on the structural, morphological, optical, photocurrent and photocatalytic properties of the resultant samples were investigated systematically. Results reveal that Ti3+ self-doping enhances the photoabsorption capability of titanium–zinc hybrid oxidesmore » in the visible-light region. Moreover, different processes and Ti/Zn molar ratios play great influences on the structure, morphology, optical, photocurrent and photocatalytic properties of the final products. Ti3+ self-doped titanium–zinc hybrid oxides exhibit excellent photocurrent and photocatalytic activity than pure TiO2 and ZnTiO3 under visible-light irradiation (λ ≥ 400 nm). The most active Ti3+ self-doped titanium–zinc hybrid oxides photoanode presents significantly improved water splitting performance. The synergistic effect between the Ti3+ self-doped and heterojunctions is responsible for the enhanced performance of these materials.« less

Electrochemical and physical properties of electroplated CuO thin films.

PubMed

Dhanasekaran, V; Mahalingam, T

2013-01-01

Cupric oxide thin films have been prepared on ITO glass substrates from an aqueous electrolytic bath containing CuSO4 and tartaric acid. Growth mechanism has been analyzed using cyclic voltammetry. The role of pH on the structural, morphological, compositional, electrical and optical properties of CuO films is investigated. The structural studies revealed that the deposited films are polycrystalline in nature with a cubic structure. The preferential orientation of CuO thin films is found to be along (111) plane. X-ray line profile analysis has been carried out to determine the microstructural parameters of CuO thin films. The pyramid shaped grains are observed from SEM and AFM images. The optical band gap energy and electrical activation energy is found to be 1.45 and 0.37 eV, respectively. Also, the optical constants of CuO thin films such as refractive index (n), complex dielectric constant (epsilon) extinction coefficient (k) and optical conductivity (sigma) are evaluated.

Morphology-controlled synthesis of Co{sub 3}O{sub 4} by one step template-free hydrothermal method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhou, Keqing; Liu, Jiajia; Wen, Panyue

2015-07-15

Highlights: • Co{sub 3}O{sub 4} crystals had been synthesized by one step template-free hydrothermal method. • The H{sub 2}O{sub 2} plays a crucial role in morphological control of Co{sub 3}O{sub 4} nanostructures. • The morphology has significant effect on the optical property of Co{sub 3}O{sub 4}. - Abstract: We had developed a facile synthetic route of Co{sub 3}O{sub 4} crystals with different morphologies via one step template-free hydrothermal method. The phase and composition of the Co{sub 3}O{sub 4} were investigated by X-ray powder diffraction and Raman spectrum. The morphology and structure of the synthesized samples were characterized by scanning electronmore » microscopy and transmission electron microscopy. The H{sub 2}O{sub 2} played a crucial role in morphological control of Co{sub 3}O{sub 4} nanostructures. It only obtained Co-based precursor in the absence of H{sub 2}O{sub 2}. On the contrary, the Co{sub 3}O{sub 4} with different morphologies including nanoparticles, nano-discs and well-defined octahedral nanostructures were synthesized in the presence of H{sub 2}O{sub 2}. In addition, the optical property of the obtained Co{sub 3}O{sub 4} samples was investigated by UV–vis spectra.« less

Effect of annealing on the optical properties of amorphous Se79Te10Sb4Bi7 thin films

NASA Astrophysics Data System (ADS)

Nyakotyo, H.; Sathiaraj, T. S.; Muchuweni, E.

2017-07-01

Thin films of Se79Te10Sb4Bi7, were prepared by Electron beam deposition technique. The structure of the as-prepared and annealed films has been studied by X-ray diffraction and the surface morphology by the scanning electron microscope (SEM). These studies show that there is a gradual change in structure and the formation of some polycrystalline structures in the amorphous phases is observed when the Se79Te10Sb4Bi7 film is annealed in the temperature range of 333-393 K. The optical transmission of these films has been studied as a function of photon wavelength in the range 300-2500 nm. It has been found that the optical band gap Egopt decreased with increasing annealing temperature in the range 333-393 K. The Urbach energy (Eu), optical conductivity (σopt), imaginary (εi), and real (εr) parts of the complex dielectric constant (ε) and lattice dielectric constant (εL) were also determined. The changes noticed in optical parameters with increasing annealing temperature were explained on the basis of structural relaxation as well as change in defect states and density of localized states due to amorphous-crystalline transformation.

Depth-resolved imaging of colon tumor using optical coherence tomography and fluorescence laminar optical tomography (Conference Presentation)

NASA Astrophysics Data System (ADS)

Tang, Qinggong; Frank, Aaron; Wang, Jianting; Chen, Chao-wei; Jin, Lily; Lin, Jon; Chan, Joanne M.; Chen, Yu

2016-03-01

Early detection of neoplastic changes remains a critical challenge in clinical cancer diagnosis and treatment. Many cancers arise from epithelial layers such as those of the gastrointestinal (GI) tract. Current standard endoscopic technology is unable to detect those subsurface lesions. Since cancer development is associated with both morphological and molecular alterations, imaging technologies that can quantitative image tissue's morphological and molecular biomarkers and assess the depth extent of a lesion in real time, without the need for tissue excision, would be a major advance in GI cancer diagnostics and therapy. In this research, we investigated the feasibility of multi-modal optical imaging including high-resolution optical coherence tomography (OCT) and depth-resolved high-sensitivity fluorescence laminar optical tomography (FLOT) for structural and molecular imaging. APC (adenomatous polyposis coli) mice model were imaged using OCT and FLOT and the correlated histopathological diagnosis was obtained. Quantitative structural (the scattering coefficient) and molecular imaging parameters (fluorescence intensity) from OCT and FLOT images were developed for multi-parametric analysis. This multi-modal imaging method has demonstrated the feasibility for more accurate diagnosis with 87.4% (87.3%) for sensitivity (specificity) which gives the most optimal diagnosis (the largest area under receiver operating characteristic (ROC) curve). This project results in a new non-invasive multi-modal imaging platform for improved GI cancer detection, which is expected to have a major impact on detection, diagnosis, and characterization of GI cancers, as well as a wide range of epithelial cancers.

Morphology-controlled synthesis of grass-like GO-CdSe nanocomposites with excellent optical properties and field emission properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xie, Pei, E-mail: peipeixie@163.com; Xue, Shaolin, E-mail: slxue@dhu.edu.cn; Wei, Jia, E-mail: Jojo.1125@hotmail.com

2016-02-15

Four different morphologies of the CdSe semiconductor nanograss have been successfully grown on graphene oxide (GO) sheets via hydrothermal method at 220 °C for 12 h. The morphologies, structures, chemical compositions and optical properties of the as-obtained GO-CdSe nanocomposites were characterized by XRD, SEM, TEM, EDS, XPS and Raman spectra. It was found that the EDTA/Cd{sup 2+} molar ratio is important for the formation of morphology of GO-CdSe nanocomposites. The results of XRD revealed that all the as-obtained GO-CdSe nanocomposites have zinc blend structure. Room temperature photoluminescence (PL) showed that the sample emits red light under different excitation wavelengths. Themore » results of Raman spectra, EDS and XPS showed that the CdSe nanograss is grown on GO sheets. The results showed that GO-CdSe nanocomposites composed of nanorods have best field emission (FE) properties with a low turn-on electric field of 4.14 V μm{sup −1} and a high field enhancement factor of 3315 among all the samples. - Graphical abstract: SEM images of as-synthesized CdSe nanograss grown on GO sheets. Room temperature PL emission spectra of the as-synthesized CdSe nanograss grown on GO sheets. Field emission J–E curve of the as-synthesized CdSe nanograss grown on GO sheets. - Highlights: • Novel CdSe nanograsses are grown on graphene oxide sheets by hydrothermal method. • The morphology of CdSe nanograsses is controlled by adjusting EDTA/Cd{sup 2+} molar ratio. • The FE performance of sample is investigated. • Optimum morphology for FE performance is CdSe nanograsses composed of nanorods on GO.« less

Spatial inhomogeneities in Al x Ga1-x N quantum wells induced by the surface morphology of AlN/sapphire templates

NASA Astrophysics Data System (ADS)

Zeimer, Ute; Jeschke, Joerg; Mogilatenko, Anna; Knauer, Arne; Kueller, Viola; Hoffmann, Veit; Kuhn, Christian; Simoneit, Tino; Martens, Martin; Wernicke, Tim; Kneissl, Michael; Weyers, Markus

2015-11-01

The effects of the template on the optical and structural properties of Al0.75Ga0.25N/Al0.8Ga0.2N multiple quantum well (MQWs) laser active regions have been investigated. The laser structures for optical pumping were grown on planar c-plane AlN/sapphire as well as on thick epitaxially laterally overgrown (ELO) AlN layers on patterned AlN/sapphire. Two ELO AlN/sapphire templates were investigated, one with a miscut of the sapphire surface to the m-direction with an angle of 0.25°, the other with a miscut angle of 0.25° to the sapphire a-direction. The MQWs are studied by atomic force microscopy, plan-view cathodoluminescence (CL) at room temperature and 83 K as well as transmission electron microscopy using high-angle annular dark-field imaging and energy-dispersive x-ray spectroscopy. The results are compared to optical pumping measurements. It was found that the surface morphology of the templates determines the lateral wavelength distribution in the MQWs observed by spectral CL mappings. The lateral wavelength spread is largest for the laser structures grown on ELO AlN with miscut to sapphire a-direction caused by the local variation of the MQW thicknesses and the Ga incorporation at macrosteps on the ELO-AlN. A CL peak wavelength spread of up to 7 nm has been found. The MQWs grown on planar AlN/sapphire templates show a homogeneous wavelength distribution. However, due to the high threading dislocation density and the resulting strong nonradiative recombination, laser operation could not be achieved. The laser structures grown on ELO AlN/sapphire show optically pumped lasing with a record short wavelength of 237 nm.

Porous silicon-VO{sub 2} based hybrids as possible optical temperature sensor: Wavelength-dependent optical switching from visible to near-infrared range

DOE Office of Scientific and Technical Information (OSTI.GOV)

Antunez, E. E.; Salazar-Kuri, U.; Estevez, J. O.

Morphological properties of thermochromic VO{sub 2}—porous silicon based hybrids reveal the growth of well-crystalized nanometer-scale features of VO{sub 2} as compared with typical submicron granular structure obtained in thin films deposited on flat substrates. Structural characterization performed as a function of temperature via grazing incidence X-ray diffraction and micro-Raman demonstrate reversible semiconductor-metal transition of the hybrid, changing from a low-temperature monoclinic VO{sub 2}(M) to a high-temperature tetragonal rutile VO{sub 2}(R) crystalline structure, coupled with a decrease in phase transition temperature. Effective optical response studied in terms of red/blue shift of the reflectance spectra results in a wavelength-dependent optical switching withmore » temperature. As compared to VO{sub 2} film over crystalline silicon substrate, the hybrid structure is found to demonstrate up to 3-fold increase in the change of reflectivity with temperature, an enlarged hysteresis loop and a wider operational window for its potential application as an optical temperature sensor. Such silicon based hybrids represent an exciting class of functional materials to display thermally triggered optical switching culminated by the characteristics of each of the constituent blocks as well as device compatibility with standard integrated circuit technology.« less

CuInGaSe{sub 2} nanoparticles by pulsed laser ablation in liquid medium

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mendivil, M.I.; García, L.V.; Krishnan, B.

2015-12-15

Highlights: • CIGS nanocolloids were synthesized using PLAL technique. • Characterized their morphology, structure, composition and optical properties. • Morphologies were dependent on ablation wavelength and liquid medium. • Optical absorption and bandgap of these nanocolloids were tunable. - Abstract: Pulsed laser ablation in liquid medium (PLALM) is a nanofabrication technique to produce complex nanostructures. CuInGaSe{sub 2} (CIGS) is an alloy with applications in photovoltaic industry. In this work, we studied the effects of laser ablation wavelength, energy fluence and liquid medium on the properties of the CIGS nanoparticles synthesized by PLALM. The nanoparticles obtained were analyzed by transmission electronmore » microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), selected area electron diffraction (SAED), X-ray photoelectron spectroscopy (XPS) and UV–vis absorption spectroscopy. XPS results confirmed the chemical states and composition of the ablated products. TEM analysis showed different morphologies for the nanomaterials obtained in different liquid media and ablation wavelengths. The optical properties for these CIGS nanocolloids were analyzed using UV–vis absorption spectroscopy. The results demonstrated the use of PLALM as a useful synthesis technique for nanoparticles of quaternary photovoltaic materials.« less

Cell death monitoring using quantitative optical coherence tomography methods

NASA Astrophysics Data System (ADS)

Farhat, Golnaz; Yang, Victor X. D.; Kolios, Michael C.; Czarnota, Gregory J.

2011-03-01

Cell death is characterized by a series of predictable morphological changes, which modify the light scattering properties of cells. We present a multi-parametric approach to detecting changes in subcellular morphology related to cell death using optical coherence tomography (OCT). Optical coherence tomography data were acquired from acute myeloid leukemia (AML) cells undergoing apoptosis over a period of 48 hours. Integrated backscatter (IB) and spectral slope (SS) were computed from OCT backscatter spectra and statistical parameters were extracted from a generalized gamma (GG) distribution fit to OCT signal intensity histograms. The IB increased by 2-fold over 48 hours with significant increases observed as early as 4 hours. The SS increased in steepness by 2.5-fold with significant changes at 12 hours, while the GG parameters were sensitive to apoptotic changes at 24 to 48 hours. Histology slides indicated nuclear condensation and fragmentation at 24 hours, suggesting the late scattering changes could be related to nuclear structure. A second series of measurements from AML cells treated with cisplatin, colchicine or ionizing radiation suggested that the GG parameters could potentially differentiate between modes of cell death. Distinct cellular morphology was observed in histology slides obtained from cells treated under each condition.

Extrinsic curvature, geometric optics, and lamellar order on curved substrates

NASA Astrophysics Data System (ADS)

Kamien, Randall D.; Nelson, David R.; Santangelo, Christian D.; Vitelli, Vincenzo

2009-11-01

When thermal energies are weak, two-dimensional lamellar structures confined on a curved substrate display complex patterns arising from the competition between layer bending and compression in the presence of geometric constraints. We present broad design principles to engineer the geometry of the underlying substrate so that a desired lamellar pattern can be obtained by self-assembly. Two distinct physical effects are identified as key factors that contribute to the interaction between the shape of the underlying surface and the resulting lamellar morphology. The first is a local ordering field for the direction of each individual layer, which tends to minimize its curvature with respect to the three-dimensional embedding. The second is a nonlocal effect controlled by the intrinsic geometry of the surface that forces the normals to the (nearly incompressible) layers to lie on geodesics, leading to caustic formation as in optics. As a result, different surface morphologies with predominantly positive or negative Gaussian curvature can act as converging or diverging lenses, respectively. By combining these ingredients, as one would with different optical elements, complex lamellar morphologies can be obtained. This smectic optometry enables the manipulation of lamellar configurations for the design of materials.

Noninvasive optical coherence tomography monitoring of structure and hydration changes of human corneas in different preservation media

NASA Astrophysics Data System (ADS)

Wu, Yicong; Clarke, Dominic; Mathew, Aby; Nicoud, Ian; Li, Xingde

2011-02-01

The influence of different tissue preservation (a test solution under development and a standard storage solution) on human cornea morphology, refractive index and hydration was assessed noninvasively by ultrahigh-resolution optical coherence tomography (OCT) over time. For 28 days' or 15 days' storage in the preservation media, corneas in the two media exhibited different structural changes with different onset times including epithelial desquamation, edema-induced cornea thickening and change in tissue refractive index. It was found that the variation of the group refractive index over time was only about 2%, while 25% variation of hydration was observed in the storage and subsequent return to normothermic conditions in both preservation media. The results suggest the two media involved different but correlated preservation mechanisms. This study demonstrates that the noncontact, noninvasive, and high-resolution OCT is a powerful tool for noninvasive characterization of tissue morphological changes and hydration process and for assessment of the effects of preservation media on stored tissue integrity. Engineers.

Eco-friendly and green synthesis of BiVO4 nanoparticle using microwave irradiation as photocatalayst for the degradation of Alizarin Red S

NASA Astrophysics Data System (ADS)

Abraham, S. Daniel; David, S. Theodore; Bennie, R. Biju; Joel, C.; Kumar, D. Sanjay

2016-06-01

Bismuth vanadate (BiVO4) nanocrystals have been successfully synthesised using microwave-assisted combustion synthesis (MCS), and characterised using Fourier transform infrared (FT-IR) and Raman spectra, surface area analysis (BET), X-ray diffraction (XRD), scanning electron microscopy (SEM), Energy Dispersive X-ray analysis (EDX), diffused reflectance spectroscopy (DRS) and Photoluminescence (PL) spectroscopy. The XRD results confirmed the formation of monoclinic bismuth vanadate. The formations of BiO & VO43-vibrations were ascertained from FT-IR data. The morphology of hallow internal structural micro entities were confirmed by SEM. The optical properties were determined by DRS and PL spectra. Hence, the influence of the preparation methods on the structure, morphology and optical activities of bismuth vanadate was investigated systematically. Photocatalytic degradation (PCD) of Alizarin Red S (ARS), an effective disrupting chemical in aqueous medium was investigated using BiVO4 nanoparticles. The kinetics of PCD was found to follow pseudo first-order.

The morphological changes of optically cleared cochlea using optical coherence tomography (Conference Presentation)

NASA Astrophysics Data System (ADS)

Lee, Jaeyul; Song, Jaewon; Jeon, Mansik; Kim, Jeehyun

2017-02-01

In this study, we monitored the optical clearing effects by immersing ex vivo guinea pig cochlea samples in ethylenediaminetetraacetic acid (EDTA) to study the internal microstructures in the morphology of guinea pig cochlea. The imaging limitations due to the guinea pig cochlea structures were overcome by optical clearing technique. Subsequently, the study was carried out to confirm the required approximate immersing duration of cochlea in EDTA-based optical clearing to obtain the best optimal depth visibility for guinea pig cochlea samples. Thus, we implemented a decalcification-based optical clearing effect to guinea pig cochlea samples to enhance the depth visualization of internal microstructures using swept source optical coherence tomography (OCT). The obtained nondestructive two-dimensional OCT images successfully illustrated the feasibility of the proposed method by providing clearly visible microstructures in the depth direction as a result of decalcification. The most optimal clearing outcomes for the guinea pig cochlea were obtained after 14 consecutive days. The quantitative assessment results verified the increase of the intensity as well as the thickness measurements of the internal microstructures. Following this method, difficulties in imaging of internal cochlea microstructures of guinea pigs could be avoided. The obtained results verified that the depth visibility of the decalcified ex vivo guinea pig cochlea samples was enhanced. Therefore, the proposed EDTA-based optical clearing method for guinea pig can be considered as a potential application for depth-enhanced OCT visualization.

Impact of the Nanoscale Gap Morphology on the Plasmon Coupling in Asymmetric Nanoparticle Dimer Antennas.

PubMed

Popp, Paul S; Herrmann, Janning F; Fritz, Eva-Corinna; Ravoo, Bart Jan; Höppener, Christiane

2016-03-23

Coupling of plasmon resonances in metallic gap antennas is of interest for a wide range of applications due to the highly localized strong electric fields supported by these structures, and their high sensitivity to alterations of their structure, geometry, and environment. Morphological alterations of asymmetric nanoparticle dimer antennas with (sub)-nanometer size gaps are assigned to changes of their optical response in correlative dark-field spectroscopy and high-resolution transmission electron microscopy (HR-TEM) investigations. This multimodal approach to investigate individual dimer structures clearly demonstrates that the coupling of the plasmon modes, in addition to well-known parameters such as the particle geometry and the gap size, is also affected by the relative alignment of both nanoparticles. The investigations corroborate that the alignment of the gap forming facets, and with that the gap area, is crucial for their scattering properties. The impact of a flat versus a rounded gap structure on the optical properties of equivalent dimers becomes stronger with decreasing gap size. These results hint at a higher confinement of the electric field in the gap and possibly a different onset of quantum transport effects for flat and rounded gap antennas in corresponding structures for very narrow gaps. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Electrodeposited Ni nanowires-track etched P.E.T. composites as selective solar absorbers

NASA Astrophysics Data System (ADS)

Lukhwa, R.; Sone, B.; Kotsedi, L.; Madjoe, R.; Maaza, M.

2018-05-01

This contribution reports on the structural, optical and morphological properties of nanostructured flexible solar-thermal selective absorber composites for low temperature applications. The candidate material in the system is consisting of electrodeposited nickel nano-cylinders embedded in track-etched polyethylene terephthalate (PET) host membrane of pore sizes ranging between 0.3-0.8µm supported by conductive nickel thin film of about 0.5µm. PET were irradiated with 11MeV/u high charged xenon (Xe) ions at normal incidence. The tubular and metallic structure of the nickel nano-cylinders within the insulator polymeric host forms a typical ceramic-metal nano-composite "Cermet". The produced material was characterized by the following techniques: X-ray diffraction (XRD) for structural characterization to determine preferred crystallographic structure, and grain size of the materials; Scanning electron microscopy (SEM) to determine surface morphology, particle size, and visual imaging of distribution of structures on the surface of the substrate; Atomic force microscopy (AFM) to characterize surface roughness, surface morphology, and film thickness, and UV-Vis-NIR spectrophotometer to measure the reflectance, then to determine solar absorption

Aggregate nanostructures of organic molecular materials.

PubMed

Liu, Huibiao; Xu, Jialiang; Li, Yongjun; Li, Yuliang

2010-12-21

Conjugated organic molecules are interesting materials because of their structures and their electronic, electrical, magnetic, optical, biological, and chemical properties. However, researchers continue to face great challenges in the construction of well-defined organic compounds that aggregate into larger molecular materials such as nanowires, tubes, rods, particles, walls, films, and other structural arrays. Such nanoscale materials could serve as direct device components. In this Account, we describe our recent progress in the construction of nanostructures formed through the aggregation of organic conjugated molecules and in the investigation of the optical, electrical, and electronic properties that depend on the size or morphology of these nanostructures. We have designed and synthesized functional conjugated organic molecules with structural features that favor assembly into aggregate nanostructures via weak intermolecular interactions. These large-area ordered molecular aggregate nanostructures are based on a variety of simpler structures such as fullerenes, perylenes, anthracenes, porphyrins, polydiacetylenes, and their derivatives. We have developed new methods to construct these larger structures including organic vapor-solid phase reaction, natural growth, association via self-polymerization and self-organization, and a combination of self-assembly and electrochemical growth. These methods are both facile and reliable, allowing us to produce ordered and aligned aggregate nanostructures, such as large-area arrays of nanowires, nanorods, and nanotubes. In addition, we can synthesize nanoscale materials with controlled properties. Large-area ordered aggregate nanostructures exhibit interesting electrical, optical, and optoelectronic properties. We also describe the preparation of large-area aggregate nanostructures of charge transfer (CT) complexes using an organic solid-phase reaction technique. By this process, we can finely control the morphologies and sizes of the organic nanostructures on wires, tubes, and rods. Through field emission studies, we demonstrate that the films made from arrays of CT complexes are a new kind of cathode materials, and we systematically investigate the effects of size and morphology on electrical properties. Low-dimension organic/inorganic hybrid nanostructures can be used to produce new classes of organic/inorganic solid materials with properties that are not observed in either the individual nanosize components or the larger bulk materials. We developed the combined self-assembly and templating technique to construct various nanostructured arrays of organic and inorganic semiconductors. The combination of hybrid aggregate nanostructures displays distinct optical and electrical properties compared with their individual components. Such hybrid structures show promise for applications in electronics, optics, photovoltaic cells, and biology. In this Account, we aim to provide an intuition for understanding the structure-function relationships in organic molecular materials. Such principles could lead to new design concepts for the development of new nonhazardous, high-performance molecular materials on aggregate nanostructures.

Hybrid structure of biotemplate-zinc-tin oxide for better optical, morphological and photocatalytic properties

NASA Astrophysics Data System (ADS)

Karpuraranjith, M.; Thambidurai, S.

2017-03-01

A new chitosan (as biotemplate)-zinc-tin oxide hybrid structure was successfully synthesized by a chemical precipitation method and annealed at 500 °C. We studied the structural changes, optical, thermal and photo catalytic properties. The chemical bonding of the Zn-O and Sn-O-Sn functional groups were confirmed by FT-IR absorption peaks appearing at 538 and 635 cm-1. The different ratio of ZnO to SnO2 particles on the biotemplate matrix altered the morphology of the hybrids from an agglomerated state to a microcrystalline form confirmed by HR-SEM and TEM analysis. The formation of a Zn0.15Sn0.85O hybrid structure was observed in the visible light region, with an energy band gap of ˜3.19 eV and higher surface area of 98 m2 g-1. The thermal property shows that CS-Zn0.15Sn0.85O has a higher thermal stability than a CS-Zn0.25Sn0.75O hybrid structure. The results demonstrate that the biotemplate-zinc-tin oxide hybrid structure has a reinforced effect compared to the other components. Therefore, a biotemplate-based zinc-tin oxide hybrid structure could be a promising material for better dye removal efficiency, which was obtained for ˜100 and 96% with MB and RY-15 dyes.

Characterization of Pb-Doped GaN Thin Films Grown by Thermionic Vacuum Arc

NASA Astrophysics Data System (ADS)

Özen, Soner; Pat, Suat; Korkmaz, Şadan

2018-03-01

Undoped and lead (Pb)-doped gallium nitride (GaN) thin films have been deposited by a thermionic vacuum arc (TVA) method. Glass and polyethylene terephthalate were selected as optically transparent substrates. The structural, optical, morphological, and electrical properties of the deposited thin films were investigated. These physical properties were interpreted by comparison with related analysis methods. The crystalline structure of the deposited GaN thin films was hexagonal wurtzite. The optical bandgap energy of the GaN and Pb-doped GaN thin films was found to be 3.45 eV and 3.47 eV, respectively. The surface properties of the deposited thin films were imaged using atomic force microscopy and field-emission scanning electron microscopy, revealing a nanostructured, homogeneous, and granular surface structure. These results confirm that the TVA method is an alternative layer deposition system for Pb-doped GaN thin films.

Structural, morphological and optical properties of LiCo0.5Ni0.45Ag0.05O2 thin films

NASA Astrophysics Data System (ADS)

Haider, Adawiya J.; AL-Rsool, Rusul Abed; AL-Tabbakh, Ahmed A.; Al-Gebori, Abdul Nasser M.; Mohamed, Aliaa

2018-05-01

Pulsed Laser Deposition (PLD) method has been successfully used for the synthesized of nano-crystalline cathode m aterial LiCo0.5Ni0.45Ag0.05O2 (LCNAO) thin film. LCNAO Ferromagnetic using pulsed Nd-YAG laser with wavelength (λ = 532 nm) and duration (10 ns) and energy fluence (1.4 J/cm2) with different substrate temperature (100, 200, 300) ˚C and O2 pressure at 10 mbar. The structural, morphological and optical properties of the films were determined by X-ray Diffraction (XRD), Scan Electron Microscopy (SEM), Atomic Force microscope (AFM) and UV-VIS spectroscopy respectively. It is observed that partial layer to spinel transformation takes place during post annealing and the average particle size of the LiCo0.5Ni0.45Ag0.05O2 is found to be (1-12) nm from SEM measurement. Finally the optical properties of the thin films have been studied at different Substrate temperature. It found the energy gap decreases from 4.2 to 3.8 eV when the substrate's temperature increasing from 100° C into 300 °C of the LCNAO films. These mean that the optical quality of LCNAO films is improved due to the increase in crystalline size and reduction of defect sites.

Optical properties of nanocrystalline Y2O3 thin films grown on quartz substrates by electron beam deposition

NASA Astrophysics Data System (ADS)

Wiktorczyk, Tadeusz; Biegański, Piotr; Serafińczuk, Jarosław

2016-09-01

Yttrium oxide thin films of a thickness 221-341 nm were formed onto quartz substrates by reactive physical vapor deposition in an oxygen atmosphere. An electron beam gun was applied as a deposition source. The effect of substrate temperature during film deposition (in the range of 323-673 K) on film structure, surface morphology and optical properties was investigated. The surface morphology studies (with atomic force microscopy and diffuse spectra reflectivity) show that the film surface was relatively smooth with RMS surface roughness in the range of 1.7-3.8 nm. XRD analysis has revealed that all diffraction lines belong to a cubic Y2O3 structure. The films consisted of small nanocrystals. Their average grain size increases from 1.6 nm to 22 nm, with substrate temperature rising from 323 K to 673 K. Optical examinations of transmittance and reflectance were performed in the spectral range of 0.2-2.5 μm. Optical constants and their dispersion curves were determined. Values of the refractive index of the films were in the range of n = 1.79-1.90 (at 0.55 μm) for substrate temperature during film deposition of 323-673 K. The changes in the refractive index upon substrate temperature correspond very well with the increase in the nanocrystals grain diameter and with film porosity.

A Multi-Anatomical Retinal Structure Segmentation System for Automatic Eye Screening Using Morphological Adaptive Fuzzy Thresholding

PubMed Central

Elleithy, Khaled; Elleithy, Abdelrahman

2018-01-01

Eye exam can be as efficacious as physical one in determining health concerns. Retina screening can be the very first clue for detecting a variety of hidden health issues including pre-diabetes and diabetes. Through the process of clinical diagnosis and prognosis; ophthalmologists rely heavily on the binary segmented version of retina fundus image; where the accuracy of segmented vessels, optic disc, and abnormal lesions extremely affects the diagnosis accuracy which in turn affect the subsequent clinical treatment steps. This paper proposes an automated retinal fundus image segmentation system composed of three segmentation subsystems follow same core segmentation algorithm. Despite of broad difference in features and characteristics; retinal vessels, optic disc, and exudate lesions are extracted by each subsystem without the need for texture analysis or synthesis. For sake of compact diagnosis and complete clinical insight, our proposed system can detect these anatomical structures in one session with high accuracy even in pathological retina images. The proposed system uses a robust hybrid segmentation algorithm combines adaptive fuzzy thresholding and mathematical morphology. The proposed system is validated using four benchmark datasets: DRIVE and STARE (vessels), DRISHTI-GS (optic disc), and DIARETDB1 (exudates lesions). Competitive segmentation performance is achieved, outperforming a variety of up-to-date systems and demonstrating the capacity to deal with other heterogeneous anatomical structures. PMID:29888146

Effects of various deposition times and RF powers on CdTe thin film growth using magnetron sputtering

NASA Astrophysics Data System (ADS)

Ghorannevis, Z.; Akbarnejad, E.; Ghoranneviss, M.

2016-09-01

Cadmium telluride (CdTe) is a p-type II-VI compound semiconductor, which is an active component for producing photovoltaic solar cells in the form of thin films, due to its desirable physical properties. In this study, CdTe film was deposited using the radio frequency (RF) magnetron sputtering system onto a glass substrate. To improve the properties of the CdTe film, effects of two experimental parameters of deposition time and RF power were investigated on the physical properties of the CdTe films. X-ray Diffraction (XRD), atomic force microscopy (AFM) and spectrophotometer were used to study the structural, morphological and optical properties of the CdTe samples grown at different experimental conditions, respectively. Our results suggest that film properties strongly depend on the experimental parameters and by optimizing these parameters, it is possible to tune the desired structural, morphological and optical properties. From XRD data, it is found that increasing the deposition time and RF power leads to increasing the crystallinity as well as the crystal sizes of the grown film, and all the films represent zinc blende cubic structure. Roughness values given from AFM images suggest increasing the roughness of the CdTe films by increasing the RF power and deposition times. Finally, optical investigations reveal increasing the film band gaps by increasing the RF power and the deposition time.

Optical characterization of porous silicon microcavities for glucose oxidase biosensing

NASA Astrophysics Data System (ADS)

Palestino, G.; Agarwal, V.; Garcia, D. B.; Legros, R.; Pérez, E.; Gergely, C.

2008-04-01

PSi microcavity (PSiMc) is characterized by a narrow resonance peak in the optical spectrum that is very sensitive to small changes in the refractive index. We report that the resonant optical cavities of PSi structures can be used to enhance the detection of labeled fluorescent biomolecules. Various PSi configurations were tested in order to compare the optical response of the PSi devices to the capture of organic molecules. Morphological and topographical analyses were performed on PSiMc using Atomic Force (AFM) and Scanning Electron (SEM) microscopies. The heterogeneity in pores lengths resulting from etching process assures a better penetration of larger molecules into the pores and sensor sensitivity depends on the pore size. Molecular detection is monitored by the successive red shifts in the reflectance spectra after the stabilization of PSiMc with 3-aminopropyltriethoxysilane (APTES). The glucose oxidase was cross linked into the PSiMc structures following a silane-glutaraldehyde (GTA) chemistry.

Microstructural, optical and electrical transport properties of Cd-doped SnO2 nanoparticles

NASA Astrophysics Data System (ADS)

Ahmad, Naseem; Khan, Shakeel; Mohsin Nizam Ansari, Mohd

2018-03-01

We have successfully investigated the structural, optical and dielectric properties of Cd assimilated SnO2 nanoparticles synthesized via very convenient precipitation route. The structural properties were studied by x-ray diffraction method (XRD) and Fourier Transform Infrared (FTIR) Spectroscopy. As-synthesized samples in the form of powder were examined for its morphology and average particle size by Transmission electron microscopy (TEM). The optical properties were studied by diffuse reflectance spectroscopy. Dielectric properties such that complex dielectric constant and ac conductivity were investigated by LCR meter. Average crystallite size calculated by XRD and average particle size obtained from TEM were found to be consistent and below 50 nm for all samples. The optical band gap of as-synthesized powder samples from absorption study was found in the range of 3.76 to 3.97 eV. The grain boundary parameters such that Rgb, Cgb and τ were evaluated using impedance spectroscopy.

Effects of Starting Precursor Ratio on Optoelectrical Properties and Blue Emission of Nanostructured C-ZnS Thin Films Prepared by Spin Coating

NASA Astrophysics Data System (ADS)

Rahimzadeh, N.; Ghodsi, F. E.; Mazloom, J.

2018-02-01

Nanocrystalline cubic zinc sulfide (C-ZnS) thin films have been elaborated by sol-gel spin-coating of Zn(Ac)/thiourea starting precursors at different molar ratios, and their structural, morphological, compositional, optical, electrical, and photoluminescence properties comprehensively investigated. x-ray diffraction results showed that the samples had dominant cubic structure and their crystallinity improved with increasing S content. Morphological characterization of the C-ZnS thin films was carried out by field-emission scanning electron microscopy (FESEM), revealing that the films were smooth with spherical grains included in clusters. Energy-dispersive x-ray and Fourier-transform infrared spectra of ZnS compounds did not show any evidence of impurities. Optical characterization revealed increases of the average optical transmittance and bandgap (from 3.2 eV to 3.56 eV) with increasing S content. The refractive index in the visible region increased with the S content, while the extinction coefficient decreased. The compositional dependence of the optical dispersion parameters (oscillator and dispersion energy), dielectric constant, and surface energy loss function of the films was evaluated. Electrical characterization of the films was carried out using Hall-effect measurements. The ZnS thin films exhibited n-type conductivity, and the electrical resistivity decreased with increasing carrier concentration and mobility due to enhanced crystallite size and reduced structural disorder. Photoluminescence (PL) measurements indicated a blue-shift of the near-band-edge emission. The blue emission peaks centered at about 438 nm and 487 nm were enhanced due to transitions involving interstitial S atoms, surface states, and zinc vacancies.

Effect of content silver and heat treatment temperature on morphological, optical, and electrical properties of ITO films by sol-gel technique

NASA Astrophysics Data System (ADS)

Mirzaee, Majid; Dolati, Abolghasem

2014-09-01

Silver-doped indium tin oxide thin films were synthesized using sol-gel dip-coating technique. The influence of different silver-dopant contents and annealing temperature on the electrical, optical, structural, and morphological properties of the films were characterized by means of four-point probe, UV-Vis spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and X-ray photoelectron spectroscope (XPS). XRD analysis confirmed the formation of cubic bixbyte structure of In2O3 with silver nanoparticles annealed at 350 °C. XPS analysis showed that divalent tin transformed to tetravalent tin through oxidization, and silver nanoparticles embedded into ITO matrix covered with silver oxide shell, resulting in high quality nanocomposite thin films. The embedment of polyvinylpyrrolidone inhibited the growth of silver nanoparticles and ITO annealed at 350 °C. Delafossite structure of tin-doped AgInO2 was found at higher annealing temperatures. XRD analysis and FESEM micrographs showed that the optimum temperature to prevent the formation of AgInO2 is 350 °C. The embedment of silver particles (5-10 nm) from reduction of silver ion in ITO thin films improved the electrical conductivity and optical transmittance of ITO nanolayers. The lowest stable sheet resistance of 1,952 Ω/Sq for a 321 nm thick and an average optical transmittance of 91.8 % in the visible region with a band gap of 3.43 eV were achieved for silver-doping content of 0.04 M.

Optimization of surface morphology and scattering properties of TCO/AIT textured glass front electrode for thin film solar cells

NASA Astrophysics Data System (ADS)

Addonizio, M. L.; Fusco, L.; Antonaia, A.; Cominale, F.; Usatii, I.

2015-12-01

Aluminium induced texture (AIT) method has been used for obtaining highly textured glass substrate suitable for silicon based thin film solar cell technology. Wet etch step parameters of AIT process have been varied and effect of different etchants and different etching times on morphological and optical properties has been analyzed. The resulting morphology features (shape, size distribution, inclination angle) have been optimized in order to obtain the best scattering properties. ZnO:Ga (GZO) films have been deposited by sputtering technique on AIT-processed glass. Two different ZnO surface morphologies have been obtained, strongly depending on the underlying glass substrate morphology induced by different etching times. Very rough and porous texture (σrms ∼ 150 nm) was obtained on glass etched 2 min showing cauliflower-like structure, whereas a softer texture (σrms ∼ 78 nm) was obtained on glass etched 7 min giving wider and smoother U-shaped craters. The effect of different glass textures on optical confinement has been tested in amorphous silicon based p-i-n devices. Devices fabricated on GZO/high textured glass showed a quantum efficiency enhancement due to both an effective light trapping phenomenon and an effective anti-reflective optical behaviour. Short etching time produce smaller cavities (<1 μm) with deep U-shape characterized by high roughness, high inclination angle and low autocorrelation length. This surface morphology promoted a large light scattering phenomenon, as evidenced by haze value and by angular resolved scattering (ARS) behaviour, into a large range of diffraction angles, giving high probability of effective light trapping inside a PV device.

Effect of substrates on structural and optical properties of tin oxide (SnO2) nanostructures.

PubMed

Johari, Anima; Bhatnagar, M C; Rana, Vikas

2012-10-01

We report on controlling the morphology of tin oxide (SnO2) nanostructures and the study of the effect of surface morphology on structural and optical properties of SnO2 nanostuctures. In present work, Tin oxide (SnO2) nanostructures such as nanowires and nanorods have been grown by thermal evaporation of SnO2 powder. To demonstrate the effect of different substrates on the morphology of grown SnO2 nanostructures, the thermal evaporation of SnO2 powder was carried out on Si and gold catalyzed Si (Au/Si) substrates. The scanning-electron-microscopic analysis shows the growth of SnO2 nanowires on Au/Si substrate and growth of SnO2 nanorods on Si substrate. The scanning-and transmission-electron-microscopic analysis shows that the diameter of SnO2 nanowires and nanorods are about 70 nm and 95 nm respectively and their length is about 80 microm and 30 microm respectively. The vapor-liquid-solid (VLS) growth of SnO2 nanowires and vapor-solid (VS) growth of SnO2 nanorods is also confirmed with the help of TEM and EDX spectra. The synthesized SnO2 nanowires show tetragonal rutile structure of SnO2, whereas SnO2 nanorods show tetragonal rutile as well as cassiterite structure of SnO2. UV-Vis absorption spectra showed the optical band gaps of 4.1 eV and 3.8 eV for the SnO2 nanowires and the nanorods, respectively. The SnO2 nanowires and nanorods show photoluminescence with broad emission peaks centred at around 600 nm and 580 nm respectively. Raman spectra of SnO2 nanowires shows three Raman shifts (478, 632, 773 cm(-1)) corresponding to Eg, A1g and B2g vibration modes, whereas in Raman spectra of SnO2 nanorods, A1g peak is dramatically reduced and the B2g mode is totally quenched.

Morphology-dependent photo-induced polarization recovery in ferroelectric thin films

NASA Astrophysics Data System (ADS)

Wang, J. Y.; Liu, G.; Sando, D.; Nagarajan, V.; Seidel, J.

2017-08-01

We investigate photo-induced ferroelectric domain switching in a series of Pb(Zr0.2Ti0.8)O3/La0.7Sr0.3MnO3 (PZT/LSMO) bilayer thin films with varying surface morphologies by piezoresponse force microscopy under light illumination. We demonstrate that reverse poled ferroelectric regions can be almost fully recovered under laser irradiation of the PZT layer and that the recovery process is dependent on the surface morphology on the nanometer scale. The recovery process is well described by the Kolmogorov-Avrami-Ishibashi model, and the evolution speed is controlled by light intensity, sample thickness, and initial write voltage. Our findings shed light on optical control of the domain structure in ferroelectric thin films with different surface morphologies.

Structural, electrical and optical properties of nanostructured ZrO2 thin film deposited by SILAR method

NASA Astrophysics Data System (ADS)

Salodkar, R. V.; Belkhedkar, M. R.; Nemade, S. D.

2018-05-01

Successive Ionic Layer Adsorption and Reaction (SILAR) method has been employed to deposit nanocrystalline ZrO2 thin film of thickness 91 nm onto glass substrates using ZrOCl2.8H2O and NaOH as cationic and anionic precursors respectively. The structural and surface morphological characterizations have been carried out by means of X-ray diffraction and field emission scanning electron microscopy confirms the nanocrystalline nature of ZrO2 thin film. The direct optical band gap and activation energy of the ZrO2 thin film are found to be 4.74 and 0.80eV respectively.

Growth features and spectroscopic structure investigations of nanoprofiled AlN films formed on misoriented GaAs substrates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Seredin, P. V., E-mail: paul@phys.vsu.ru; Goloshchapov, D. L.; Lenshin, A. S.

Nanostructured aluminum-nitride films are formed by reactive ion-plasma sputtering onto GaAs substrates with different orientations. The properties of the films are studied via structural analysis, atomic force microscopy, and infrared and visible–ultraviolet spectroscopy. The aluminum-nitride films can have a refractive index in the range of 1.6–4.0 at a wavelength of ~250 nm and an optical band gap of ~5 eV. It is shown that the morphology, surface composition, and optical characteristics of AlN/GaAs heterophase systems can be controlled using misoriented GaAs substrates.

Combined multi-modal photoacoustic tomography, optical coherence tomography (OCT) and OCT angiography system with an articulated probe for in vivo human skin structure and vasculature imaging

PubMed Central

Liu, Mengyang; Chen, Zhe; Zabihian, Behrooz; Sinz, Christoph; Zhang, Edward; Beard, Paul C.; Ginner, Laurin; Hoover, Erich; Minneman, Micheal P.; Leitgeb, Rainer A.; Kittler, Harald; Drexler, Wolfgang

2016-01-01

Cutaneous blood flow accounts for approximately 5% of cardiac output in human and plays a key role in a number of a physiological and pathological processes. We show for the first time a multi-modal photoacoustic tomography (PAT), optical coherence tomography (OCT) and OCT angiography system with an articulated probe to extract human cutaneous vasculature in vivo in various skin regions. OCT angiography supplements the microvasculature which PAT alone is unable to provide. Co-registered volumes for vessel network is further embedded in the morphologic image provided by OCT. This multi-modal system is therefore demonstrated as a valuable tool for comprehensive non-invasive human skin vasculature and morphology imaging in vivo. PMID:27699106

Investigations on the change of texture of plant cells due to preservative treatments by digital holographic microscopy

NASA Astrophysics Data System (ADS)

Vora, Priyanka; Anand, Arun

2014-10-01

Texture change is observed in preserved fruits and vegetables. Responsible factors for texture change during preservative treatments are cell morphology, cell wall structure, cell turger, water content and some biochemical components, and also the environmental conditions. Digital Holographic microscopy (DHM) is a quantitative phase contrast imaging technique, which provides three dimensional optical thickness profiles of transparent specimen. Using DHM the morphology of plant cells preserved by refrigeration or stored in vinegar or in sodium chloride can be obtained. This information about the spatio-temporal evolution of optical volume and thickness can be an important tool in area of food processing. Also from the three dimensional images, the texture of the cell can be retrieved and can be investigated under varying conditions.

Growth of pure ZnO thin films prepared by chemical spray pyrolysis on silicon

NASA Astrophysics Data System (ADS)

Ayouchi, R.; Martin, F.; Leinen, D.; Ramos-Barrado, J. R.

2003-01-01

Structural, morphological, optical and electrical properties of ZnO thin films prepared by chemical spray pyrolysis from zinc acetate (Zn(CH 3COO) 2 2H 2O) aqueous solutions, on polished Si(1 0 0), and fused silica substrates for optical characterization, have been studied in terms of deposition time and substrate temperature. The growth of the films present three regimes depending on the substrate temperature, with increasing, constant and decreasing growth rates at lower, middle, and higher-temperature ranges, respectively. Growth rate higher than 15 nm min -1 can be achieved at Ts=543 K. ZnO film morphological and electrical properties have been related to these growth regimes. The films have been characterized by X-ray diffraction, scanning electron microscopy and X-ray photoelectron spectroscopy.

Correlation between corneal thickness and optic disc morphology in normal tension glaucoma using modern technical analysis.

PubMed

Coman, Laurenţiu; Costescu, Monica; Alecu, Mihail; Coman, Oana Andreia

2014-01-01

The purpose of this study was to evaluate the relationship between central corneal thickness (CCT) and optic disc morphology in normal tension glaucoma (NTG). Patients with NTG underwent eye examination, optic disc imaging with Heildelberg Retina Tomograph II (HRT II) and ultrasound corneal pachymetry. The morphological parameters of the optic discs were used to classify the eyes into four groups: generalized enlargement (GE) type, myopic glaucomatous (MY) type, focal ischemic (FI) type and senile sclerotic (SS) type. A correlation between CCT and optic disc morphology obtained by HRT II was calculated. Multiple comparison and post hoc tests were performed in order to determine the significance of the differences between the four groups. The strongest correlation was between CCT and the parameters of optic disc imaging obtained at HRT II in the GE type of optic disc.

Macro optical projection tomography for large scale 3D imaging of plant structures and gene activity

PubMed Central

Lee, Karen J. I.; Calder, Grant M.; Hindle, Christopher R.; Newman, Jacob L.; Robinson, Simon N.; Avondo, Jerome J. H. Y.

2017-01-01

Abstract Optical projection tomography (OPT) is a well-established method for visualising gene activity in plants and animals. However, a limitation of conventional OPT is that the specimen upper size limit precludes its application to larger structures. To address this problem we constructed a macro version called Macro OPT (M-OPT). We apply M-OPT to 3D live imaging of gene activity in growing whole plants and to visualise structural morphology in large optically cleared plant and insect specimens up to 60 mm tall and 45 mm deep. We also show how M-OPT can be used to image gene expression domains in 3D within fixed tissue and to visualise gene activity in 3D in clones of growing young whole Arabidopsis plants. A further application of M-OPT is to visualise plant-insect interactions. Thus M-OPT provides an effective 3D imaging platform that allows the study of gene activity, internal plant structures and plant-insect interactions at a macroscopic scale. PMID:28025317

The effect of induced strains on photoluminescence properties of ZnO nanostructures grown by thermal evaporation method

NASA Astrophysics Data System (ADS)

Arjmand, Yaser; Eshghi, Hosein

2016-03-01

In this paper, ZnO nanostructures have been synthesized by thermal evaporation process using metallic zinc powder in the presence of oxygen on p-Si (100) at different distances from the boat. The structural and optical characterizations have been carried out. The morphological study shows various shape nanostructures. XRD data indicate that all samples have a polycrystalline wurtzite hexagonal structure in such a way that the closer sample has a preferred orientation along (101) while the ones farther are grown along (002) direction. From the structural and optical data analysis, we found that the induced strains are the main parameter controlling the UV/green peaks ratios in the PL spectra of the studied samples.

Magnesium-Aluminum-Zirconium Oxide Amorphous Ternary Composite: A Dense and Stable Optical Coating

NASA Technical Reports Server (NTRS)

Sahoo, N. K.; Shapiro, A. P.

1998-01-01

In the present work, the process parameter dependent optical and structural properties of MgO-Al(2)O(3)-ZrO(2) ternary mixed-composite material have been investigated. Optical properties were derived from spectrophotometric measurements. The surface morphology, grain size distributions, crystallographic phases and process dependent material composition of films have been investigated through the use of Atomic Force Microscopy (AFM), X-ray diffraction analysis and Energy Dispersive X- ray (EDX) analysis. EDX analysis made evident the correlation between the optical constants and the process dependent compositions in the films. It is possible to achieve environmentally stable amorphous films with high packing density under certain optimized process conditions.

MgO-Al2O3-ZrO2 Amorphous Ternary Composite: A Dense and Stable Optical Coating

NASA Technical Reports Server (NTRS)

Shaoo, Naba K.; Shapiro, Alan P.

1998-01-01

The process-parameter-dependent optical and structural properties of MgO-Al2O3-ZrO2 ternary mixed-composite material were investigated. Optical properties were derived from spectrophotometric measurements. The surface morphology, grain size distributions, crystallographic phases, and process- dependent material composition of films were investigated through the use of atomic force microscopy, x-ray diffraction analysis, and energy-dispersive x-ray analysis. Energy-dispersive x-ray analysis made evident the correlation between the optical constants and the process-dependent compositions in the films. It is possible to achieve environmentally stable amorphous films with high packing density under certain optimized process conditions.

Morphological driven photocatalytic activity of ZnO nanostructures

NASA Astrophysics Data System (ADS)

Abbas, Khaldoon N.; Bidin, Noriah

2017-02-01

Using a simple combination of pulse laser ablation in liquid and hydrothermal (PLAL-H) approaches, we control the morphology of ZnO nanostructures (ZNSs) to determine the feasibility of their photocatalytic efficacy. These ZNSs are deposited on Si (100) substrates and two different morphologies are achieved. In this synergistic approach, PLAL synthesized NSs are used as a nutrient solution with different pH for further hydrothermal treatment at 110 °C under varying growth time (5, 30 and 60 min). Surface morphology, structure, composition, and optical characteristics of the prepared ZNSs are determined using FESEM, XRD, FTIR and Photoluminescence (PL) and UV-vis absorption measurements. The morphology revealed remarkable transformation from nanorods (NRs)/nanoflowers (NFs) (at pH 7.6) to nanoparticles (NPs)-like (at pH 10.5) structure. XRD patterns showed better polycrystallinity for NPs with enlarged band gap than NR/NF-like structures. Both PL and UV-vis spectral analysis of ZNPs exhibited higher surface area and deep level defects density dependent morphology, where the nutrient pH and growth time variation are found to play a significant role towards structural evolution. Furthermore, the photocatalytic activities of, such ZNSs are evaluated via sunlight driven photo-degradation of methylene blue (MB) dye. The photocatalytic efficiency of ZNPs is demonstrated to be much superior (97.4%) than ZNRs/ZNFs-like morphology (86%). Such enhanced photocatalytic activities of as-synthesized ZNPs is attributed to the synergism of the improved surface area and defects density, which is useful for promoting the adsorption of the MB dye and suppressed surface recombination of photo-generated charge carriers.

Optical and morphological properties of sol gel derived titanium dioxide films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sharma, A. B.; Sharma, S. K.; M, Vishwas

2015-08-28

Titanium oxide (Titania) thin films were synthesized on different substrates via the sol-gel dip-coating method using alkoxide solution. Some selected samples were also prepared with different percentage of Lead (Pb). The influence of Pb addition in precursor sol on the optical properties of titanium dioxide thin films was studied. The optical transmittance in the visible region has increased with increase in weight percentage of lead. The refractive index was slightly decreased with Pb addition. Crystallization of these coatings was achieved through thermal annealing at temperatures above 400 °C. The structural properties and surface morphology of the crystallized coatings were studiedmore » by Scanning Electron Microscopy. Increase in average grain size from 250 nm to 350 nm with increase in Pb concentration is observed. Films were appeared to more coarse with increase in Pb addition. An increase in Pb addition resulted increase in average roughness from 12 nm to 25 nm.« less

The role of Mg dopant on the morphological, structural and optical properties of Mg doped zinc oxide grown through hydrothermal method

NASA Astrophysics Data System (ADS)

Susetyo, P.; Fauzia, V.; Sugihartono, I.

2017-04-01

ZnO nanorods is a low cost II-VI semiconductor compound with huge potential to be applied in optoelectronic devices i.e. light emitting diodes, solar cells, gas sensor, spintronic devices and lasers. In order to improve the electrical and optical properties, group II, III and IV elements were widely investigated as dopand elements on ZnO. In this work, magnesium (Mg) was doped into ZnO nanorods. Samples were prepared firstly by deposition of undoped ZnO seed layer on indium thin oxide coated glass substrates by ultrasonic spray pyrolysis method and then followed by the growth of ZnO nanorods doped by three different Mg concentrations by hydrothermal method. Based on the morphological, microstructural and optical characterizations results, it is concluded that the increase of magnesium concentration tends to reduce the diameter of ZnO nanorods, increases the bandgap energy and decreases the UV absorption the luminescence in UV and visible range.

Effect of catalyst concentration on size, morphology and optical properties of silica nanoparticles

NASA Astrophysics Data System (ADS)

Arora, Ekta; Ritu, Kumar, Sacheen; Kumar, Dinesh

2016-05-01

Today, nanomaterials play a key role in various fields such as electronics, aerospace, pharmaceuticals and biomedical because of their unique physical, chemical and biological properties which are different from bulk materials. Nano sized silica particles have gained the prominent position in scientific research and have wide applications. The sol-gel method is the best method to synthesize silica nanoparticles because of its potential to produce monodispersed with narrow size distribution at mild conditions. The silica nanoparticles were obtained by hydrolysis of tetraethyl orthosilicate (TEOS) in ethanol act as solvent. The synthesized nanoparticles were characterized by Field Emission Scanning electron Microscope (FE-SEM), UV Spectrometer. The smallest size of silica particles is around 150nm examined by using FE-SEM. The optical properties and band structure was analyzed using UV-visible spectroscopy which is found to be increase by reducing the size of particles. Concentration effect of catalyst on the size, morphology and optical properties were analyzed.

Effect of catalyst concentration on size, morphology and optical properties of silica nanoparticles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Arora, Ekta; Ritu,; Kumar, Sacheen, E-mail: sacheen3@gmail.com

2016-05-06

Today, nanomaterials play a key role in various fields such as electronics, aerospace, pharmaceuticals and biomedical because of their unique physical, chemical and biological properties which are different from bulk materials. Nano sized silica particles have gained the prominent position in scientific research and have wide applications. The sol-gel method is the best method to synthesize silica nanoparticles because of its potential to produce monodispersed with narrow size distribution at mild conditions. The silica nanoparticles were obtained by hydrolysis of tetraethyl orthosilicate (TEOS) in ethanol act as solvent. The synthesized nanoparticles were characterized by Field Emission Scanning electron Microscope (FE-SEM),more » UV Spectrometer. The smallest size of silica particles is around 150nm examined by using FE-SEM. The optical properties and band structure was analyzed using UV-visible spectroscopy which is found to be increase by reducing the size of particles. Concentration effect of catalyst on the size, morphology and optical properties were analyzed.« less

Studies on morphology, electrical and optical characteristics of Al-doped ZnO thin films grown by atomic layer deposition

NASA Astrophysics Data System (ADS)

Chen, Li; Chen, Xinliang; Zhou, Zhongxin; Guo, Sheng; Zhao, Ying; Zhang, Xiaodan

2018-03-01

Al doped ZnO (AZO) films deposited on glass substrates through the atomic layer deposition (ALD) technique are investigated with various temperatures from 100 to 250 °C and different Zn : Al cycle ratios from 20 : 0 to 20 : 3. Surface morphology, structure, optical and electrical properties of obtained AZO films are studied in detail. The Al composition of the AZO films is varied by controlling the ratio of Zn : Al. We achieve an excellent AZO thin film with a resistivity of 2.14 × 10‑3 Ω·cm and high optical transmittance deposited at 150 °C with 20 : 2 Zn : Al cycle ratio. This kind of AZO thin films exhibit great potential for optoelectronics device application. Project supported by the State Key Development Program for Basic Research of China (Nos. 2011CBA00706, 2011CBA00707) and the Tianjin Applied Basic Research Project and Cutting-Edge Technology Research Plan (No. 13JCZDJC26900).

Tuning effect of polysaccharide Chitosan on structural, morphological, optical and photoluminescence properties of ZnO nanoparticles

NASA Astrophysics Data System (ADS)

Magesh, G.; Bhoopathi, G.; Nithya, N.; Arun, A. P.; Ranjith Kumar, E.

2018-05-01

Chitosan/ZnO nanocomposites was synthesized by in-situ chemical precipitation method. The effect of polysaccharide Chitosan concentration (0.1 g, 0.5 g, 1 g and 3 g) was investigated by X-ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM) with Energy dispersive spectroscopy (EDX), High Resolution Transmission Electron Microscopy (HRTEM), UV-visible (UV), Fourier Transform Infrared (FTIR) and Photoluminescence Spectroscopy (PL). XRD pattern confirms the hexagonal wurtzite structure of the Chitosan/ZnO nanocomposites. The structural morphology and the elemental composition of the samples were analysed by FESEM and EDX respectively. From TEM analysis, it is observed that the particles in spindle shape morphology with average particle size ranges 10-20 nm. UV-Vis analysis reveals that the Chitosan concentration affect the absorption band edge and shift towards lower wavelength. The oxygen vacancy induced photoluminescence of ZnO nanoparticles was observed and its intensity decreases by tuning the Chitosan concentration.

Lithography-free glass surface modification by self-masking during dry etching

NASA Astrophysics Data System (ADS)

Hein, Eric; Fox, Dennis; Fouckhardt, Henning

2011-01-01

Glass surface morphologies with defined shapes and roughness are realized by a two-step lithography-free process: deposition of an ~10-nm-thin lithographically unstructured metallic layer onto the surface and reactive ion etching in an Ar/CF4 high-density plasma. Because of nucleation or coalescence, the metallic layer is laterally structured during its deposition. Its morphology exhibits islands with dimensions of several tens of nanometers. These metal spots cause a locally varying etch velocity of the glass substrate, which results in surface structuring. The glass surface gets increasingly rougher with further etching. The mechanism of self-masking results in the formation of surface structures with typical heights and lateral dimensions of several hundred nanometers. Several metals, such as Ag, Al, Au, Cu, In, and Ni, can be employed as the sacrificial layer in this technology. Choice of the process parameters allows for a multitude of different glass roughness morphologies with individual defined and dosed optical scattering.

Metal cluster's effect on the optical properties of cesium bromide thin films

NASA Astrophysics Data System (ADS)

Kumar, Kuldeep; Arun, P.; Ravi Kant, Chhaya; Juluri, Bala Krishna

2012-06-01

Cesium bromide (CsBr) films grown on glass substrates by thermal evaporation showed prominent absorption peaks in the UV-visible region. Interestingly, these absorption spectra showed peaks which red shifted over time in ambient exposure. Structural and morphological studies suggested decrease in particle size overtime which was unusual. Electron micrographs show the formation of "daughter" cesium nanorods from parent CsBr particles. Theoretical calculations show the optical behavior observed to be due to localized surface plasmon resonance resulting from cesium nanorods.

Telepathology and Optical Biopsy

PubMed Central

Ferrer-Roca, Olga

2009-01-01

The ability to obtain information about the structure of tissue without taking a sample for pathology has opened the way for new diagnostic techniques. The present paper reviews all currently available techniques capable of producing an optical biopsy, with or without morphological images. Most of these techniques are carried out by physicians who are not specialized in pathology and therefore not trained to interpret the results as a pathologist would. In these cases, the use of telepathology or distant consultation techniques is essential. PMID:20339507

Morphological study of the TK cholangiocarcinoma cell line with three-dimensional cell culture.

PubMed

Akiyoshi, Kohei; Kamada, Minori; Akiyama, Nobutake; Suzuki, Masafumi; Watanabe, Michiko; Fujioka, Kouki; Ikeda, Keiichi; Mizuno, Shuichi; Manome, Yoshinobu

2014-04-01

Cholangiocarcinoma is an intractable carcinoma originating from the bile duct epithelium. To gain an understanding of the cell biology of cholangiocarcinoma, in vitro cell culture is valuable. However, well‑characterized cell lines are limited. In the present study, the morphology of the TK cholangiocarcinoma cell line was analyzed by three‑dimensional culture. Dispersed TK cells were injected into a gelatin mesh scaffold and cultivated for 3‑20 days. The morphology of the TK cells was investigated by phase‑contrast microscopy, optical microscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). TK cells were observed to proliferate three-dimensionally in the scaffold. The cells exhibited a globoid structure and attached to the scaffold. The SEM observation demonstrated typical microvilli and plicae on the surface of the structure. Light microscopy and TEM confirmed intercellular and cell‑to‑scaffold attachment in the three‑dimensional mesh. The culture also exhibited the formation of a duct-like structure covered by structured microvilli. In conclusion, three‑dimensional culture of TK cells demonstrated the morphological characteristics of cholangiocarcinoma in vitro. Production of high levels of carbohydrate antigen (CA)19‑9, CA50 and carcinoembryonic antigen was previously confirmed in the TK cell line. As a characteristic morphology was demonstrated in the present study, the TK cholangiocarcinoma cell line may be useful as an experimental model for further study of cholangiocarcinoma.

Morphological Control of Co3O4 and Its Photocatalytic Properties

EPA Science Inventory

Cobaltosic oxide (Co3O4), a p-type semiconductor, belongs to the normal spinel crystal structure based on a cubic close packing array of oxide ions. The size, surface, geometry, and crystal phase of catalysts are important parameters for controlling their chemical, optical, and ...

Investigation of the influence of vanadium, iron and nickel dopants on the morphology, and crystal structure and photocatalytic properties of titanium dioxide based nanopowders.

PubMed

Shao, Godlisten N; Jeon, Sun-Jeong; Haider, M Salman; Abbass, Nadir; Kim, Hee Taik

2016-07-15

Photoactive V, Fe and Ni doped TiO2 (M-TiO2) nanopowders were synthesized by a modified two-step sol-gel process in the absence of additives. Titanium oxychloride, which is a rarely-used TiO2 precursor was used to yield M-TiO2 photocatalysts with preferential photochemical performance in the presence of natural solar irradiation. The obtained samples were calcined at different calcination temperatures ranging from 450 to 800°C to evaluate the influence of the sintering on the physicochemical properties. The properties of the obtained samples were examined by XRF, XRD, Raman spectroscopy, UV-visible DRS, XPS, nitrogen gas physisorption studies, SEM-EDAX and HRTEM analyses. Structural characterization of the samples revealed the incorporation of these transition metal element into TiO2. It was also depicted that the morphology, crystal structure, optical and photochemical properties of the obtained samples were largely dependent on the calcination temperature and the type of dopant used during the preparation process. The photochemical performance of the samples was investigated in the photodegradation of methylene blue in the presence of natural sunlight. The experimental results indicated that the VT600 sample possessed the highest activity due to its superior properties. This study provides a systematic preparation and selection of the precursor, dopant and calcination temperature that are suitable for the formation of TiO2-based heterogeneous photocatalysts with appealing morphology, crystal structure, optical and photochemical properties for myriad of applications. Copyright © 2016 Elsevier Inc. All rights reserved.

Photoinduced electro-optics measurements of biosilica transformation to cristobalite

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fuchs, Ido; Aluma, Yaniv; Ilan, Micha

2015-03-15

In this paper we studied the photoinduced electro optics effects in the thermal transformation process of biosilica to cristobalite, at a relatively low temperature and ambient pressure. This process was characterized by a variety of standards techniques with emphasis on linear electro optic effect measurements. Overall we demonstrated that photoinduced electro optics measurements are very sensitive to the transformation from amorphous structure of silica in the natural sponge samples to laminar string morphology of cristobalite. With this technique we could probe the change in the samples chirality from achiral bio silica to chiral cristobalite structure. Furthermore it is shown thatmore » natural biosilica have photoinduced linear electro optics respond indicating the chiral natural of biosilica. - Graphical abstract: The phase transformation of biosilica from marine sponges to Cristobalite under thermal treatment was investigated using photoinduced electro optics measurements. The figure shows the changes of the electro-optic coefficient of cristobalite and biosilica. - Highlights: • We examine phase transformation of biosilica. • We report transition from amorphous biosilica to crystalline Cristobalite. • Biosilica transformation to Cristobalite at temperature of 850 °C. • Biosilica transformation is studied with photoinduced measurements. • We examine changes in the photoinduced linear electro optics properties.« less

Structural, morphological and optical studies of ripple-structured ZnO thin films

NASA Astrophysics Data System (ADS)

Navin, Kumar; Kurchania, Rajnish

2015-11-01

Ripple-structured ZnO thin films were prepared on Si (100) substrate by sol-gel spin-coating method with different heating rates during preheating process and finally sintered at 500 °C for 2 h in ambient condition. The structural, morphological and photoluminescence (PL) properties of the nanostructured films were analyzed by X-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM) and PL spectroscopy. XRD analysis revealed that films have hexagonal wurtzite structure and texture coefficient increases along (002) plane with preheating rate. The faster heating rate produced higher crystallization and larger average crystallite size. The AFM and SEM images indicate that all the films have uniformly distributed ripple structure with skeletal branches. The number of ripples increases, while the rms roughness, amplitude and correlation length of the ripple structure decrease with preheating rates. The PL spectra show the presence of different defects in the structure. The ultraviolet emission improved with the heating rate which indicates its better crystallinity.

Structural, morphological, optical and biological properties of pure ZnO and agar/zinc oxide nanocomposites.

PubMed

Magesh, G; Bhoopathi, G; Nithya, N; Arun, A P; Ranjith Kumar, E

2018-05-26

In this work, ZnO nanoparticles were prepared by in situ chemical precipitation method in the presence of Agar biopolymer. The influence of Agar concentrations on the structural, morphological and optical properties of ZnO have been investigated. The XRD pattern of Pure ZnO and Agar/ZnO nanocomposites indicates the hexagonal wurtzite phase of ZnO. The crystallite size of pure ZnO and Agar/ZnO nanocomposites was found to be in the range of 35.5 to 19.73 nm. Pure ZnO and Agar/ZnO nanocomposites showed nanospheroid and nanopaddy shaped morphology from FESEM studies. The interplanar distance observed from the HRTEM image confirms the plane of the prepared material. The elemental composition of the samples were characterized by EDX. The optical properties of Pure ZnO and Agar/ZnO nanocomposites were characterized by UV, FTIR and PL. The band gap of Agar/ZnO nanocomposites were varied with the Agar concentration. Oxygen vacancy induced photoluminescence of ZnO are observed and its intensity is found to be increased linearly with the Agar concentration. The antibacterial activity of ZnO and Agar/ZnO nanocomposites was evaluated by disc diffusion method against Gram-positive (B.subtilis) and Gram-negative (P. aeruginosa) bacteria. The cytotoxicity of Agar/ZnO nanocomposites was studied against Normal (L929) and Breast cancer cell line (MB231). The result of this investigation reveals that the Agar/ZnO nanocomposites deliver a dose dependent toxicity in normal and cancer cell line. Copyright © 2018. Published by Elsevier B.V.

Giant Optical Activity of Quantum Dots, Rods, and Disks with Screw Dislocations

NASA Astrophysics Data System (ADS)

Baimuratov, Anvar S.; Rukhlenko, Ivan D.; Noskov, Roman E.; Ginzburg, Pavel; Gun'Ko, Yurii K.; Baranov, Alexander V.; Fedorov, Anatoly V.

2015-10-01

For centuries mankind has been modifying the optical properties of materials: first, by elaborating the geometry and composition of structures made of materials found in nature, later by structuring the existing materials at a scale smaller than the operating wavelength. Here we suggest an original approach to introduce optical activity in nanostructured materials, by theoretically demonstrating that conventional achiral semiconducting nanocrystals become optically active in the presence of screw dislocations, which can naturally develop during the nanocrystal growth. We show the new properties to emerge due to the dislocation-induced distortion of the crystal lattice and the associated alteration of the nanocrystal’s electronic subsystem, which essentially modifies its interaction with external optical fields. The g-factors of intraband transitions in our nanocrystals are found comparable with dissymmetry factors of chiral plasmonic complexes, and exceeding the typical g-factors of chiral molecules by a factor of 1000. Optically active semiconducting nanocrystals—with chiral properties controllable by the nanocrystal dimensions, morphology, composition and blending ratio—will greatly benefit chemistry, biology and medicine by advancing enantiomeric recognition, sensing and resolution of chiral molecules.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mthethwa, T.P.; Moloto, M.J., E-mail: mmoloto@uj.ac.za; De Vries, A.

Graphical abstract: SEM images of CdS/PMMA showing coiling as loading of CdS nanoparticles is increased. Thermal stability is increased with increase in %loading of both CdS and CdSe nanoparticles. Research highlights: {yields} TOPO-capped CdS and HDA-capped CdSe nanoparticles were synthesized and fully characterized. {yields} The nanoparticles were mixed with the polymer, PMMA using electrospinning technique using 2, 5 and 10% weight loadings. {yields} The mixture was spun to produce fibres with optical and thermal properties showing significant change and also the increase in loading causing bending or spiraling. {yields} Both TEM images for nanoparticles and SEM for fibres shows themore » morphology and sizes of the particles. -- Abstract: Electrospinning technique was used to fabricate poly(methyl methacrylate) (PMMA) fibres incorporating CdS and CdSe quantum dots (nanoparticles). Different nanoparticle loadings (2, 5 and 10 wt% with respect to PMMA) were used and the effect of the quantum dots on the properties of the fibres was studied. The optical properties of the hybrid composite fibres were investigated by photoluminescence and UV-vis spectrophotometry. Scanning electron microscopy (SEM), X-ray diffraction and FTIR spectrophotometry were also used to investigate the morphology and structure of the fibres. The optical studies showed that the size-tunable optical properties can be achieved in the polymer fibres by addition of quantum dots. SEM images showed that the morphologies of the fibres were dependent on the added amounts of quantum dots. A spiral type of morphology was observed with an increase in the concentration of CdS and CdSe nanoparticles. Less beaded structures and bigger diameter fibres were obtained at higher quantum dot concentrations. X-ray diffractometry detected the amorphous peaks of the polymer and even after the quantum dots were added and the FTIR analysis shows that there was no considerable interaction between the quantum dots and the polymer fibres at low concentration of quantum dots however at higher concentrations some interactions were observed which shows that QDs were present on the surfaces of the fibres.« less

Variation of microstructural and optical properties in SILAR grown ZnO thin films by thermal treatment.

PubMed

Valanarasu, S; Dhanasekaran, V; Chandramohan, R; Kulandaisamy, I; Sakthivelu, A; Mahalingam, T

2013-08-01

The influence of thermal treatment on the structural and morphological properties of the ZnO films deposited by double dip Successive ionic layer by adsorption reaction is presented. The effect of annealing temperature and time in air ambient is presented in detail. The deposited films were annealed from 200 to 400 degrees C in air and the structural properties were determined as a function of annealing temperature by XRD. The studies revealed that films were exhibiting preferential orientation along (002) plane. The other structural parameters like the crystallite size (D), micro strain (epsilon), dislocation density (delta) and stacking fault (alpha) of as-deposited and annealed ZnO films were evaluated and reported. The optical properties were also studied and the band gap of the ZnO thins films varied from 3.27 to 3.04 eV with the annealing temperature. SEM studies revealed that the hexagonal shaped grains with uniformly distributed morphology in annealed ZnO thin films. It has been envisaged using EDX analysis that the near stoichiometric composition of the film can be attained by thermal treatment during which microstructural changes do occur.

Influence of Annealing Duration on the Growth of V2O5 Nanorods Synthesized by Spray Pyrolysis Technique

NASA Astrophysics Data System (ADS)

Abd-Alghafour, N. M.; Ahmed, Naser M.; Hassan, Z.; Abubakar, D.; Bououdina, M.

2016-06-01

This paper deals with the investigation of annealing effects on the structural, morphological and optical properties of V2O5 nanorods (NRs) grown on the glass substrates by using chemical spray pyrolysis technique. The as-prepared samples were annealed at 500∘ for 40, 60 and 120 min in a quartz tube furnace. The high resolution X-ray diffraction (XRD) analysis revealed V2O5 NRs with preferred orientation along (001) plane. The crystallite size of the V2O5 NRs was increased by increasing the annealing duration. The morphological observations using field emission scanning electron microscope (FESEM) displayed NRs structures whose diameter and length were found to increase with increase of the annealing duration. The transmission electron microscopy (TEM) analysis confirmed the orthorhombic structures of the NRs. The AFM measurements indicated an increase of the average surface roughness by increasing the annealing time. The Raman spectroscopy revealed V-O-V phonon mode in the NRs annealed for 120 min. The optical bandgap was found in the range 2.6-2.58eV and observed to decrease with various duration annealed.

Investigation on structural, thermal, optical and sensing properties of meta-stable hexagonal MoO(3) nanocrystals of one dimensional structure.

PubMed

Chithambararaj, Angamuthuraj; Bose, Arumugam Chandra

2011-01-01

Hexagonal molybdenum oxide (h-MoO(3)) was synthesized by a solution based chemical precipitation technique. Analysis by X-ray diffraction (XRD) confirmed that the as-synthesized powder had a metastable hexagonal structure. The characteristic vibrational band of Mo-O was identified from Fourier transform infrared spectroscopy (FT-IR). Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images clearly depicted the morphology and size of h-MoO(3.) The morphology study showed that the product comprises one-dimensional (1D) hexagonal rods. From the electron energy loss spectroscopy (EELS) measurement, the elemental composition was investigated and confirmed from the characteristic peaks of molybdenum and oxygen. Thermogravimetric (TG) analysis on metastable MoO(3) revealed that the hexagonal phase was stable up to 430 °C and above this temperature complete transformation into a highly stable orthorhombic phase was achieved. The optical band gap energy was estimated from the Kubelka-Munk (K-M) function and was found to be 2.99 eV. Finally, the ethanol vapor-sensing behavior was investigated and the sensing response was found to vary linearly as a function of ethanol concentration in the parts per million (ppm) range.

Structured polarized light microscopy (SPLM) for mapping collagen fiber orientation of ocular tissues

NASA Astrophysics Data System (ADS)

Yang, Bin; Brazile, Bryn; Jan, Ning-Jiun; Voorhees, Andrew P.; Sigal, Ian A.

2018-02-01

Glaucoma is a disease characterized by progressive and irreversible vision loss leading to blindness. This vision loss is believed to be largely determined by the biomechanics of the optic nerve head region. Optic nerve head biomechanics, in turn, is determined by the properties of the constituent collagen. However, it is challenging to visualize and quantify collagen morphology and orientation in situ, and therefore often studies of the region collagen have used histological sections. Here we describe SPLM, a novel imaging technique that combines structured light illumination and polarized light microscopy (PLM) to enable collagen fiber visualization and fiber orientation mapping without requiring tissue sectioning. We developed a custom automated SPLM imaging system based on an upright microscope and a digital micromirror device (DMD) projector. The high spatial frequency patterns were used to achieve effective background suppression. Enhanced scattering sensitivity with SPLM resulted in images with highly improved visibility of collagen structures, even of tissues covered by pigment. SPLM produced improved fiber orientation maps from superficial layers compared to depth-averaged orientation from regular PLM. SPLM imaging provides valuable information of collagen fiber morphology and orientation in situ thus strengthening the study of ocular collagen fiber biomechanics and glaucoma.

Study the target effect on the structural, surface and optical properties of TiO2 thin film fabricated by RF sputtering method

NASA Astrophysics Data System (ADS)

Vyas, Sumit; Tiwary, Rohit; Shubham, Kumar; Chakrabarti, P.

2015-04-01

The effect of target (Ti metal target and TiO2 target) on Titanium Dioxide (TiO2) thin films grown on ITO coated glass substrate by RF magnetron sputtering has been investigated. A comparative study of both the films was done in respect of crystalline structure, surface morphology and optical properties by using X-ray diffractometer (XRD), Atomic Force Microscopy (AFM) studies and ellipsometric measurements. The XRD results confirmed the crystalline structure and indicated that the deposited films have the intensities of anatase phase. The surface morphology and roughness values indicated that the film using Ti metal target has a smoother surface and densely packed with grains as compared to films obtained using TiO2 target. A high transmission in the visible region, and direct band gap of 3.67 eV and 3.75 eV for films derived by using Ti metal and TiO2 target respectively and indirect bandgap of 3.39 eV for the films derived from both the targets (Ti metal and TiO2 target) were observed by the ellipsometric measurements.

The effects of surfactant on the structure of ZnCr2O4 dendrimer like nanostructures used in degradation of Eriochrome Black T

NASA Astrophysics Data System (ADS)

Sabet, Mohammad; Jahangiri, Hasan

2018-01-01

In this experimental work, we synthesized ZnCr2O4 nano dendrimer-like structures via a simple hydrothermal method. Different parameters such as the reaction time and temperature and the surfactant kind were changed to obtain different particle sizes and morphologies. Scanning electron microscopy was utilized to obtain the products morphologies. The results showed the product is mainly composed of dendrimer-like structures. Also, it was found the mentioned parameters had significant effects on the product sizes and morphologies. Furthermore, it was found key parameters that determine the morphology of the product is surfactant type and each surfactant creates a unique morphology. The crystallinity and crystallite size were studied by x-ray diffraction pattern. Also, the composition of the product was determined by energy dispersive x-ray analysis. Diffuse reflectance spectroscopy (DRS) was used to the investigation of the optical properties of the product. The results obtained from DRS spectra showed the product has about 3.3 eV band gap. The photocatalytic activity of the product showed that ZnCr2O4 has a significant photocatalytic activity and it can decompose Eriochrome Black T about 91% under ultra violet radiation.

Electronic and Crystalline Structure, Magnetic Response, and Optical Characterization of Rare-Earth Ruthenate Sr2HoRuO6

NASA Astrophysics Data System (ADS)

Velásquez Moya, X. A.; Cardona, R.; Villa Hernández, J. I.; Landínez Téllez, D. A.; Roa-Rojas, J.

2018-03-01

Sr2HoRuO6 ceramic has been synthesized and its structural, morphological, magnetic, optical, and electronic properties studied. Rietveld refinement of x-ray diffraction patterns revealed that this oxide material crystallizes in monoclinic perovskite structure in space group P2 1 /n (no. 14). Scanning electron microscopy revealed polycrystalline surface morphology. x-Ray dispersive spectroscopy suggested that Sr2HoRuO6 was obtained with expected stoichiometry. Magnetic susceptibility curves as a function of temperature revealed ferrimagnetic feature of this material below the Néel temperature T N of 14 K. Evidence of magnetic disorder was provided by the irreversibility observed in the zero-field-cooled and field-cooled responses of the susceptibility below T irr = 169 K. Analysis of the diffuse reflectance spectrum suggested that this material behaves as a semiconductor with energy gap E g of 1.38 eV. Results of band structure and density-of-states calculations are in agreement with the interpretation of Sr2HoRuO6 as a semiconductor. The ferrimagnetic behavior is interpreted as due to exchange mechanisms of d-f (Ru-O-Ho) electrons. The effective magnetic moment calculated from density functional theory was 93.5% of the experimental value obtained from Curie-Weiss fitting of the susceptibility curve.

Controlling Au Nanorod Dispersion in Thin Film Polymer Blends

NASA Astrophysics Data System (ADS)

Hore, Michael J. A.; Composto, Russell J.

2012-02-01

Dispersion of Au nanorods (Au NRs) in polymer thin films is studied using a combination of experimental and theoretical techniques. Here, we incorporate small volume fractions of polystyrene-functionalized Au NRs (φrod 0.05) into polystyrene (PS) thin films. By controlling the ratio of the brush length (N) to that of the matrix polymers (P), we can selectively obtain dispersed or aggregated Au NR structures in the PS-Au(N):PS(P) films. A dispersion map of these structures allows one to choose N and P to obtain either uniformly dispersed Au NRs or aggregates of closely packed, side-by-side aligned Au NRs. Furthermore, by blending poly(2,6-dimethyl-p-phenylene oxide) (PPO) into the PS films, we demonstrate that the Au nanorod morphology can be further tuned by reducing depletion-attraction forces and promoting miscibility of the Au NRs. These predictable structures ultimately give rise to tunable optical absorption in the films resulting from surface plasmon resonance coupling between the Au NRs. Finally, self-consistent field theoretic (SCFT) calculations for both the PS-Au(N):PS(P) and PS-Au(N):PS(P):PPO systems provide insight into the PS brush structure, and allow us to interpret morphology and optical property results in terms of wet and dry PS brush states.

Broad range tuning of structural and optical properties of Zn x Mg1-x O nanostructures grown by vapor transport method

NASA Astrophysics Data System (ADS)

Vanjaria, Jignesh V.; Azhar, Ebraheem Ali; Yu, Hongbin

2016-11-01

One-dimensional (1D) Zn x Mg1-x O nanomaterials have drawn global attention due to their remarkable chemical and physical properties, and their diverse current and future technological applications. In this work, 1D ZnMgO nanostructures with different magnesium concentrations and different morphologies were grown directly on zinc oxide-coated silicon substrates by thermal evaporation of zinc oxide, magnesium boride and graphite powders. Highly well-defined Mg-rich ZnMgO nanorods with a rock salt structure and Zn-rich ZnMgO nanostructures with a wurtzite structure have been deposited individually by careful optimization of the source mixture and process parameters. Structural and optical properties of the deposited products were studied by scanning electron microscopy, energy dispersive x-ray spectroscopy, x-ray diffraction, and Raman spectroscopy. Cathodoluminescence measurements demonstrate strong dominant peaks at 3.3 eV in Mg poor ZnMgO nanostructures and 4.8 eV in Mg rich nanostructures implying that the ZnMgO nanostructures can be used for the fabrication of deep UV optoelectronic devices. A mechanism for the formation and achieved diverse morphology of the ZnMgO nanostructures was proposed based on the characterization results.

Morphology and mixing state of atmospheric particles: Links to optical properties and cloud processing

NASA Astrophysics Data System (ADS)

China, Swarup

Atmospheric particles are ubiquitous in Earth's atmosphere and impact the environment and the climate while affecting human health and Earth's radiation balance, and degrading visibility. Atmospheric particles directly affect our planet's radiation budget by scattering and absorbing solar radiation, and indirectly by interacting with clouds. Single particle morphology (shape, size and internal structure) and mixing state (coating by organic and inorganic material) can significantly influence the particle optical properties as well as various microphysical processes, involving cloud-particle interactions and including heterogeneous ice nucleation and water uptake. Conversely, aerosol cloud processing can affect the morphology and mixing of the particles. For example, fresh soot has typically an open fractal-like structure, but aging and cloud processing can restructure soot into more compacted shapes, with different optical and ice nucleation properties. During my graduate research, I used an array of electron microscopy and image analysis tools to study morphology and mixing state of a large number of individual particles collected during several field and laboratory studies. To this end, I investigated various types of particles such as tar balls (spherical carbonaceous particles emitted during biomass burning) and dust particles, but with a special emphasis on soot particles. In addition, I used the Stony Brook ice nucleation cell facility to investigate heterogeneous ice nucleation and water uptake by long-range transported particles collected at the Pico Mountain Observatory, in the Archipelago of the Azores. Finally, I used ice nucleation data from the SAAS (Soot Aerosol Aging Study) chamber study at the Pacific Northwest National Laboratory to understand the effects that ice nucleation and supercooled water processing has on the morphology of residual soot particles. Some highlights of our findings and implications are discussed next. We found that the morphology of fresh soot emitted by vehicles depends on the driving conditions (i.e.; the vehicle specific power). Soot emitted by biomass burning is often heavily coated by other materials while processing of soot in urban environment exhibits complex mixing. We also found that long-range transported soot over the ocean after atmospheric processing is very compacted. In addition, our results suggest that freezing process can facilitate restructuring of soot and results into collapsed soot. Furthermore, numerical simulations showed strong influence on optical properties when fresh open fractal-like soot evolved to collapsed soot. Further investigation of long-range transported aged particles exhibits that they are efficient in water uptake and can induce ice nucleation in colder temperature. Our results have implications for assessing the impact of the morphology and mixing state of soot particles on human health, environment and climate. Our findings can provide guidance to numerical models such as particle-resolved mixing state models to account for, and better understand, vehicular emissions and soot evolution since its emission to atmospheric processing in urban environment and finally in remote regions after long-range transport. Morphology and mixing state information can be used to model observational-constrained optical properties. The details of morphology and mixing state of soot particles are crucial to assess the accuracy of climate models in describing the contribution of soot radiative forcing and their direct and indirect climate effects. Finally, our observations of ice nucleation ability by aged particles show that nucleated particles are internally mixed and coated with several materials.

Phototropic growth control of nanoscale pattern formation in photoelectrodeposited Se–Te films

PubMed Central

Sadtler, Bryce; Burgos, Stanley P.; Batara, Nicolas A.; Beardslee, Joseph A.; Atwater, Harry A.; Lewis, Nathan S.

2013-01-01

Photoresponsive materials that adapt their morphologies, growth directions, and growth rates dynamically in response to the local incident electromagnetic field would provide a remarkable route to the synthesis of complex 3D mesostructures via feedback between illumination and the structure that develops under optical excitation. We report the spontaneous development of ordered, nanoscale lamellar patterns in electrodeposited selenium–tellurium (Se–Te) alloy films grown under noncoherent, uniform illumination on unpatterned substrates in an isotropic electrolyte solution. These inorganic nanostructures exhibited phototropic growth in which lamellar stripes grew toward the incident light source, adopted an orientation parallel to the light polarization direction with a period controlled by the illumination wavelength, and showed an increased growth rate with increasing light intensity. Furthermore, the patterns responded dynamically to changes during growth in the polarization, wavelength, and angle of the incident light, enabling the template-free and pattern-free synthesis, on a variety of substrates, of woodpile, spiral, branched, or zigzag structures, along with dynamically directed growth toward a noncoherent, uniform intensity light source. Full-wave electromagnetic simulations in combination with Monte Carlo growth simulations were used to model light–matter interactions in the Se–Te films and produced a model for the morphological evolution of the lamellar structures under phototropic growth conditions. The experiments and simulations are consistent with a phototropic growth mechanism in which the optical near-field intensity profile selects and reinforces the dominant morphological mode in the emergent nanoscale patterns. PMID:24218617

Self-assembly of amorphous biophotonic nanostructures by phase separation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dufresne, Eric R.; Noh, Heeso; Saranathan, Vinodkumar

2009-04-23

Some of the most vivid colors in the animal kingdom are created not by pigments, but by wavelength-selective scattering of light from nanostructures. Here we investigate quasi-ordered nanostructures of avian feather barbs which produce vivid non-iridescent colors. These {beta}-keratin and air nanostructures are found in two basic morphologies: tortuous channels and amorphous packings of spheres. Each class of nanostructure is isotropic and has a pronounced characteristic length scale of variation in composition. These local structural correlations lead to strong backscattering over a narrow range of optical frequencies and little variation with angle of incidence. Such optical properties play important rolesmore » in social and sexual communication. To be effective, birds need to precisely control the development of these nanoscale structures, yet little is known about how they grow. We hypothesize that multiple lineages of birds have convergently evolved to exploit phase separation and kinetic arrest to self-assemble spongy color-producing nanostructures in feather barbs. Observed avian nanostructures are strikingly similar to those self-assembled during the phase separation of fluid mixtures; the channel and sphere morphologies are characteristic of phase separation by spinodal decomposition and nucleation and growth, respectively. These unstable structures are locked-in by the kinetic arrest of the {beta}-keratin matrix, likely through the entanglement or cross-linking of supermolecular {beta}-keratin fibers. Using the power of self-assembly, birds can robustly realize a diverse range of nanoscopic morphologies with relatively small physical and chemical changes during feather development.« less

Phototropic growth control of nanoscale pattern formation in photoelectrodeposited Se-Te films.

PubMed

Sadtler, Bryce; Burgos, Stanley P; Batara, Nicolas A; Beardslee, Joseph A; Atwater, Harry A; Lewis, Nathan S

2013-12-03

Photoresponsive materials that adapt their morphologies, growth directions, and growth rates dynamically in response to the local incident electromagnetic field would provide a remarkable route to the synthesis of complex 3D mesostructures via feedback between illumination and the structure that develops under optical excitation. We report the spontaneous development of ordered, nanoscale lamellar patterns in electrodeposited selenium-tellurium (Se-Te) alloy films grown under noncoherent, uniform illumination on unpatterned substrates in an isotropic electrolyte solution. These inorganic nanostructures exhibited phototropic growth in which lamellar stripes grew toward the incident light source, adopted an orientation parallel to the light polarization direction with a period controlled by the illumination wavelength, and showed an increased growth rate with increasing light intensity. Furthermore, the patterns responded dynamically to changes during growth in the polarization, wavelength, and angle of the incident light, enabling the template-free and pattern-free synthesis, on a variety of substrates, of woodpile, spiral, branched, or zigzag structures, along with dynamically directed growth toward a noncoherent, uniform intensity light source. Full-wave electromagnetic simulations in combination with Monte Carlo growth simulations were used to model light-matter interactions in the Se-Te films and produced a model for the morphological evolution of the lamellar structures under phototropic growth conditions. The experiments and simulations are consistent with a phototropic growth mechanism in which the optical near-field intensity profile selects and reinforces the dominant morphological mode in the emergent nanoscale patterns.

Effect of structural transformation of C+-ion implanted PMMA into quasi-continuous carbonaceous layer on its optical and electrical properties

NASA Astrophysics Data System (ADS)

Arif, Shafaq; Rafique, M. Shahid; Saleemi, Farhat; Sagheer, Riffat

2018-02-01

The samples of Polymethylmethacrylate (PMMA) have been implanted with 500 keV C+-ions at different ion fluences ranging from 9.3 × 1013 to 8.4 × 1014 ions/cm2. The structural modifications are examined by Fourier Transform Infrared and Raman spectral studies. For the investigation of optical, electrical and surface morphological properties of implanted samples UV-Visible spectrometer, four probe apparatus and optical microscope have been employed. The FTIR spectra confirmed the cleavage of chemicals bonds as a consequence of polymer chain scission, whereas, Raman studies revealed the transformation of PMMA structure into quasi-continuous amorphous carbon with increasing ion fluences. A continuous reduction has been observed in the optical band gap of PMMA from 3.16 to 1.42 eV. Moreover, the refractive index, extinction coefficient and electrical conductivity of implanted PMMA are found to be an increasing function of the ion fluence. The micrographic images revealed the signatures of ion-induced defects like cracking, dehydrogenation, stress and swelling on the surface of PMMA. These implanted samples have a potential to be used in the field of optical communications and thin plastic flexible electronics.

Immobilization Effect of Morphological, Thermal and Optical Properties in Biotemplate on Zinc Oxide Nanocomposite from Chitosan

NASA Astrophysics Data System (ADS)

Karpuraranjith, M.; Thambidurai, S.

Biotemplate-based zinc oxide nanocomposite was effectively prepared via simple chemical precipitation route. The functional groups of amino (-NH2), hydroxyl (-OH) and O-Zn-O were confirmed and characterized by FTIR spectroscopy. The structural and morphological properties were confirmed by XRD, UV-Vis DRS, HR-SEM and TEM analyses. The elemental composition of carbon, nitrogen, zinc and oxygen was confirmed by energy-dispersive X-ray analysis (EDAX) and Brunauer-Emmett-Teller high surface area of materials was estimated to be 52.49m2/g, respectively. Thermogravimetric analysis (TGA) shows that biotemplate on zinc oxide nanocomposite has higher thermal stability than chitosan matrix. The results demonstrate that biotemplate on zinc oxide matrix causes immobilization effect among the two components. Therefore, chitosan-ZnO nanocomposite has a microcrystalline morphological structure and also good thermal stability, so it can be a promising material for sensors, medical, tissue engineering and wastewater treatment applications.

Evolution of structural and optical properties of rutile TiO2 thin films synthesized at room temperature by chemical bath deposition method

NASA Astrophysics Data System (ADS)

Mayabadi, A. H.; Waman, V. S.; Kamble, M. M.; Ghosh, S. S.; Gabhale, B. B.; Rondiya, S. R.; Rokade, A. V.; Khadtare, S. S.; Sathe, V. G.; Pathan, H. M.; Gosavi, S. W.; Jadkar, S. R.

2014-02-01

Nanocrystalline thin films of TiO2 were prepared on glass substrates from an aqueous solution of TiCl3 and NH4OH at room temperature using the simple and cost-effective chemical bath deposition (CBD) method. The influence of deposition time on structural, morphological and optical properties was systematically investigated. TiO2 transition from a mixed anatase-rutile phase to a pure rutile phase was revealed by low-angle XRD and Raman spectroscopy. Rutile phase formation was confirmed by FTIR spectroscopy. Scanning electron micrographs revealed that the multigrain structure of as-deposited TiO2 thin films was completely converted into semi-spherical nanoparticles. Optical studies showed that rutile thin films had a high absorption coefficient and a direct bandgap. The optical bandgap decreased slightly (3.29-3.07 eV) with increasing deposition time. The ease of deposition of rutile thin films at low temperature is useful for the fabrication of extremely thin absorber (ETA) solar cells, dye-sensitized solar cells, and gas sensors.

Fabrication of optical filters using multilayered porous silicon

NASA Astrophysics Data System (ADS)

Gaber, Noha; Khalil, Diaa; Shaarawi, Amr

2011-02-01

In this work we describe a method for fabricating optical filters using multilayered porous silicon 1D photonic structure. An electrochemical cell is constructed to control the porosity of variable layers in p-type Si wafers. Porous silicon multilayered structures are formed of λ/4 (or multiples) thin films that construct optical interference filters. By changing the anodizing current density of the cell during fabrication, different porosities can be obtained as the optical refractive index is a direct function of the layer porosity. To determine the morphology, the wavelength dependent refractive index n and absorption coefficient α, first, porous silicon free standing mono-layers have been fabricated at different conditions and characterized in the near infrared region (from 1000 to 2500nm). Large difference in refractive index (between 1.6 and 2.6) is obtained. Subsequently, multilayer structures have been fabricated and tested. Their spectral response has been measured and it shows good agreement with numerical simulations. A technique based on inserting etching breaks is adopted to ensure the depth homogeneity. The effect of differing etching/break times on the reproducibility of the filters is studied.

Facile synthesis of one dimensional ZnO nanostructures for DSSC applications

NASA Astrophysics Data System (ADS)

Marimuthu, T.; Anandhan, N.

2016-05-01

Development of zinc oxide (ZnO) nanostructure based third generation dye sensitized solar cell is interesting compared to conventional silicon solar cells. ZnO nanostructured thin films were electrochemically deposited onto fluorine doped tin oxide (FTO) glass substrate. The effect of ethylene-diamine-tetra-acetic acid (EDTA) on structural, morphological and optical properties is investigated using X-ray diffraction (XRD) meter, field emission scanning electron microscope (FE-SEM) and micro Raman spectroscopy. XRD patterns reveal that the prepared nanostructures are hexagonal wutrzite structures with (101) plane orientation, the nanostructure prepared using EDTA exhibits better crystallinity. FE-SEM images illustrate that the morphological changes are observed from nanorod structure to cauliflower like structure as EDTA is added. Micro Raman spectra predict that cauliflower like structure possesses a higher crystalline nature with less atomic defects compared to nanorod structures. Dye sensitized solar cell (DSSC) is constructed for the optimized cauliflower structure, and open circuit voltage, short circuit density, fill factor and efficiency are estimated from the J-V curve.

Effect of Fe-ion implantation doping on structural and optical properties of CdS thin films

NASA Astrophysics Data System (ADS)

Chandramohan, S.; Kanjilal, A.; Sarangi, S. N.; Majumder, S.; Sathyamoorthy, R.; Som, T.

2010-06-01

We report on effects of Fe implantation doping-induced changes in structural, optical, morphological, and vibrational properties of cadmium sulfide thin films. Films were implanted with 90 keV Fe+ ions at room temperature for a wide range of fluences from 0.1×1016 to 3.6×1016 ions cm-2 (corresponding to 0.38-12.03 at.% of Fe). Glancing angle X-ray diffraction analysis revealed that the implanted Fe atoms tend to supersaturate by occupying the substitutional cationic sites rather than forming metallic clusters or secondary phase precipitates. In addition, Fe doping does not lead to any structural phase transformation although it induces structural disorder and lattice contraction. Optical absorption studies show a reduction in the optical band gap from 2.39 to 2.17 eV with increasing Fe concentration. This is attributed to disorder-induced band tailing in semiconductors and ion-beam-induced grain growth. The strain associated with a lattice contraction is deduced from micro-Raman scattering measurements and is found that size and shape fluctuations of grains, at higher fluences, give rise to inhomogeneity in strain.

Microscopic Imaging and Spectroscopy with Scattered Light

PubMed Central

Boustany, Nada N.; Boppart, Stephen A.; Backman, Vadim

2012-01-01

Optical contrast based on elastic scattering interactions between light and matter can be used to probe cellular structure and dynamics, and image tissue architecture. The quantitative nature and high sensitivity of light scattering signals to subtle alterations in tissue morphology, as well as the ability to visualize unstained tissue in vivo, has recently generated significant interest in optical scatter based biosensing and imaging. Here we review the fundamental methodologies used to acquire and interpret optical scatter data. We report on recent findings in this field and present current advances in optical scatter techniques and computational methods. Cellular and tissue data enabled by current advances in optical scatter spectroscopy and imaging stand to impact a variety of biomedical applications including clinical tissue diagnosis, in vivo imaging, drug discovery and basic cell biology. PMID:20617940

Composite Films Formed by Cellulose nanocrystals and Latex Nanoparticles: Optical, Structural, and Mechanical Properties

NASA Astrophysics Data System (ADS)

Vollick, Brandon McRae

This thesis describes the preparation of iridescent, birefringent, composite films composed of cellulose nanocrystals (CNCs), latex nanoparticles (NPs) and a NP crosslinker; hexanediamine (HDA). First, aqueous suspensions were prepared with varying quantities of CNCs, NPs and HDA before equilibrating for one week. The cholesteric (Ch) phase was then cast and dried into a film. The optical, structural and mechanical properties of the film was analyzed. Second, films with identical compositions of CNCs, NPs, and HDA were fabricated in three different ways to yield films of different morphology, (i) fast drying of an isotropic suspension, yielding an isotropic film, (ii) slow drying of an isotropic suspension, yielding a partially Ch films, (iii) slow drying of an equilibrated suspension, yielding a highly Ch film. The optical and mechanical properties of the films was analyzed.

Goddard X-ray astronomy contributions to the IAU/COSPAR (1982)

NASA Technical Reports Server (NTRS)

Holt, S. S.; Petre, R.; Shafer, R. A.; Urry, C. M.; Mushotzky, R. F.

1982-01-01

The relation of X-ray flux to both the continuum flux in the optical and radio bands, and to the line emission properties of these objects were studied. The Einstein Observatory, because of increased sensitivity and improved angular resolution, increased substantially the number of known X-ray emitting active galactic nuclei. The Einstein imaging instruments detected morphology in AGN X-ray emission, in particular from jetlike structures in Cen-A, M87, and 3C273. The improved energy resolution and sensitivity of the spectrometers onboard the Observatory provide information on the geometry and ionization structure of the region responsible for the broad optical emission lines in a few AGN's. This information, combined with theoretical modeling and IUE and optical observations, allows the construction of a moderately detailed picture of the broad line region in these objects.

Structural and optical properties of WTe2 single crystals synthesized by DVT technique

NASA Astrophysics Data System (ADS)

Dixit, Vijay; Vyas, Chirag; Pathak, V. M.; Soalanki, G. K.; Patel, K. D.

2018-05-01

Layered transition metal di-chalcogenide (LTMDCs) crystals have attracted much attention due to their potential in optoelectronic device applications recently due to realization of their monolayer based structures. In the present investigation we report growth of WTe2 single crystals by direct vapor transport (DVT) technique. These crystals are then characterized by energy dispersive analysis of x-rays (EDAX) to study stoichiometric composition after growth. The structural properties are studied by x-ray diffraction (XRD) and selected area electron diffraction (SAED) is used to confirm orthorhombic structure of grown WTe2 crystal. Surface morphological properties of the crystals are also studied by scanning electron microscope (SEM). The optical properties of the grown crystals are studied by UV-Visible spectroscopy which gives direct band gap of 1.44 eV for grown WTe2 single crystals.

Multipulse nanosecond laser irradiation of silicon for the investigation of surface morphology and photoelectric properties

NASA Astrophysics Data System (ADS)

Sardar, Maryam; Chen, Jun; Ullah, Zaka; Jelani, Mohsan; Tabassum, Aasma; Cheng, Ju; Sun, Yuxiang; Lu, Jian

2017-12-01

We irradiate the single crystal boron-doped silicon (Si) with different number of laser pulses at constant fluence (7.5 J cm-2) in ambient air using Nd:YAG laser and examine its surface morphology and photoelectric properties in details. The results obtained from optical micrographs reveal the increase in heat affected zone (HAZ) and melted area of laser irradiated Si with increasing number of laser pulses. The SEM micrographs evidence the formation of various surface morphologies like laser induced periodic surface structures, crater, microcracks, clusters, cavities, pores, trapped bubbles, nucleation sites, micro-bumps, redeposited material and micro- and nano-particles on the surface of irradiated Si. The surface profilometry analysis informs that the depth of crater is increased with increase in number of incident laser pulses. The spectroscopic ellipsometry reveals that the multipulse irradiation of Si changes its optical properties (refractive index and extinction coefficient). The current-voltage (I-V) characteristic curves of laser irradiated Si show that although the multipulse laser irradiation produces considerable number of surface defects and damages, the electrical properties of Si are well sustained after the multipulse irradiation. The current findings suggest that the multipulse irradiation can be an effective way to tune the optical properties of Si for the fabrication of wide range of optoelectronic devices.

A novel graphene oxide-polyimide as optical waveguide material: Synthesis and thermo-optic switch properties

NASA Astrophysics Data System (ADS)

Cao, Tianlin; Zhao, Fanyu; Da, Zulin; Qiu, Fengxian; Yang, Dongya; Guan, Yijun; Cao, Guorong; Zhao, Zerun; Li, Jiaxin; Guo, Xiaotong

2016-10-01

In this work, a novel graphene oxide-polyimide (GOPI) as optical waveguide material was prepared. The structure, mechanical, thermal property and morphology of the GOPI was characterized by using fourier transform infrared, UV-visible spectroscopy, near-infrared spectrum, thermogravimetric analysis, differential scanning calorimetry, scanning electron microscope and transmission electron microscopy. The thermo-optic coefficients (dn/dT) are -9.16 × 10-4 (532 nm), -7.56 × 10-4 (650 nm) and -4.82 × 10-4 (850 nm) °C-1, respectively. Based on the thermo-optic effect of prepared GOPI as waveguide material, a Y-branch with branching angle of 0.143° and Mach-Zehnder thermo-optic switches were designed. Using finite difference beam propagation method (FD-BPM) method, the simulation results such as power consumptions and response times of two different thermo-optic switches were obtained.

Morphology and Structure of Ultraluminous Infrared Galaxies at z ≈ 2 in the EGS Field

NASA Astrophysics Data System (ADS)

Fang, G. W.; Ma, Z. Y.; Chen, Y.; Kong, X.

2014-11-01

Using high-resolution HST WFC3 (Hubble Space Telescope Wide Field Camera 3) F160W imaging from the CANDELS-EGS (Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey-Extended Groth Strip) field, we present the morphology analysis of 9 ultraluminous infrared galaxies (ULIRGs) at z≈2. We find a wide range of morphological diversities for these ULIRGs, from spheroid to multiple bright nuclei or diffuse structures, e.g., double nuclei, bridges, dual asymmetries, irregular, or elliptical structures. In quantitative, these sources show a lower Gini coefficient (G) and a higher moment (M_{20}) in the rest-frame optical morphology, compared to the lower redshift counterparts, indicating less concentrated and symmetric spatial distribution of the stellar mass of ULIRGs at z≈2. Moreover, we derive accurate effective radii of these ULIRGs through 2-D profile fitting, which range from 2.4 to 5.8 kpc, with a mean value of (3.9±1.1) kpc. We find that the sizes of these ULIRGs at z≈2 are on average one to two times smaller than those of the local star-forming galaxies with analogous stellar mass. Our results are consistent with those studies at similar redshift and infrared luminosity.

Investigation on structural, optical and electrical properties of polythiophene-Al2O3 composites

NASA Astrophysics Data System (ADS)

Vijeth, H.; Yesappa, L.; Niranjana, M.; Ashokkumar, S. P.; Devendrappa, H.

2018-05-01

The polythiophene (PTH) and polythiophene-Al2O3 composites prepared by in situ chemical polymerisation in the presence of anionic surfactant camphor sulfonic acid (CSA). The formation of composite is confirmed by X-ray Diffraction (XRD) and Energy Dispersive X-ray spectroscopy (EDX) analysis. The surface morphology was studied using Field Emission Electron Microscopy (FESEM). Optical properties was studied using UV-visible spectroscopy, it observed decrease in the band gap reveals material has potential application in optical devices. The dielectric constant and AC conductivity of composite have been studied for different temperature in the frequency range 1 kHz -1 MHz.

Myogenic Maturation by Optical-Training in Cultured Skeletal Muscle Cells.

PubMed

Asano, Toshifumi; Ishizuka, Toru; Yawo, Hiromu

2017-01-01

Optogenetic techniques are powerful tools for manipulating biological processes in identified cells using light under high temporal and spatial resolutions. Here, we describe an optogenetic training strategy to promote morphological maturation and functional development of skeletal muscle cells in vitro. Optical stimulation with a rhythmical frequency facilitates specific structural alignment of sarcomeric proteins. Optical stimulation also depolarizes the membrane potential, and induces contractile responses in synchrony with the given pattern of light pulses. These results suggest that optogenetic techniques can be employed to manipulate activity-dependent processes during myogenic development and control contraction of photosensitive skeletal muscle cells with high temporal and special precision.

Effect of Phosphine-Free Selenium Precursor Reactivity on The Optical and Vibrational properties of Colloidal CdSe Nanocrystals

NASA Astrophysics Data System (ADS)

Thi, L. A.; Lieu, N. T. T.; Hoa, N. M.; Tran, N.; Binh, N. T.; Quang, V. X.; Nghia, N. X.

2018-03-01

Phosphine-free selenium precursor solutions have been prepared by heating at temperatures ranging from 160 °C to 240 °C and studied by means of infrared absorption spectroscopy. The colloidal CdSe nanocrystals (NCs) synthesized from all those solutions by the wet chemical method. The influence of heating temperature on the chemical reactivity of selenium precursor and its role on the optical and vibrational properties of CdSe NCs are discussed in details. Their morphology, particle size, structural, optical and vibrational properties were investigated using transmission electron microscopy, X-ray diffraction, UV-Vis, fluorescence and Raman spectroscopy, respectively.

Birefringence and vascular imaging of in vivo human skin by Jones-matrix optical coherence tomography

NASA Astrophysics Data System (ADS)

Li, En; Makita, Shuichi; Hong, Young-Joo; Kasaragod, Deepa; Yasuno, Yoshiaki

2017-02-01

A customized 1310-nm Jones-matrix optical coherence tomography (JM-OCT) for dermatological investigation was constructed and used for in vivo normal human skin tissue imaging. This system can simultaneously measure the threedimensional depth-resolved local birefringence, complex-correlation based OCT angiography (OCT-A), degree-ofpolarization- uniformity (DOPU) and scattering OCT intensity. By obtaining these optical properties of tissue, the morphology, vasculature, and collagen content of skin can be deduced and visualized. Structures in the deep layers of the epithelium were observed with depth-resolved local birefringence and polarization uniformity images. These results suggest high diagnostic and investigative potential of JM-OCT for dermatology.

Decalin-assisted light emitting porous Si formation and its optical, surface and morphological properties

NASA Astrophysics Data System (ADS)

Karatutlu, Ali; Istengir, Sumeyra; Cosgun, Sedat; Seker, Isa; Unal, Bayram

2017-11-01

In this research paper, light emitting porous silicon (Lep-Si) samples were fabricated by a surfactant-mediated chemical stain etching solution in order to form homogenous luminescent nanostructures at room temperature. As an industrially important solvent, decalin (decahydronaphtalene) was used as a surfactant in the HF/HNO3 solutions in order to control the etching process. Morphological, surface and optical properties of the Lep-Si samples were examined using atomic force microscopy, X-ray photoelectron spectroscopy, photoluminescence (PL) spectroscopy, and laser scanning confocal microscopy (LSCM) techniques. These characterization techniques were correlated with the various etching times including depth dependent luminescence profiles for the first time. We report the optimum conditions for production of the most efficient Lep-Si using decalin (decahydronaphtalene) and possible structural origins of light emission using the depth dependent luminescence measurements.

A high-sensitivity fiber-optic evanescent wave sensor with a three-layer structure composed of Canada balsam doped with GeO2.

PubMed

Zhong, Nianbing; Zhao, Mingfu; Zhong, Lianchao; Liao, Qiang; Zhu, Xun; Luo, Binbin; Li, Yishan

2016-11-15

In this paper, we present a high-sensitivity polymer fiber-optic evanescent wave (FOEW) sensor with a three-layer structure that includes bottom, inter-, and surface layers in the sensing region. The bottom layer and inter-layer are POFs composed of standard cladding and the core of the plastic optical fiber, and the surface layer is made of dilute Canada balsam in xylene doped with GeO2. We examine the morphology of the doped GeO2, the refractive index and composition of the surface layer and the surface luminous properties of the sensing region. We investigate the effects of the content and morphology of the GeO2 particles on the sensitivity of the FOEW sensors by using glucose solutions. In addition, we examine the response of sensors incubated with staphylococcal protein A plus mouse IgG isotype to goat anti-mouse IgG solutions. Results indicate very good sensitivity of the three-layer FOEW sensor, which showed a 3.91-fold improvement in the detection of the target antibody relative to a conventional sensor with a core-cladding structure, and the novel sensor showed a lower limit of detection of 0.2ng/l and a response time around 320s. The application of this high-sensitivity FOEW sensor can be extended to biodefense, disease diagnosis, biomedical and biochemical analysis. Copyright © 2016 Elsevier B.V. All rights reserved.

Temperature dependent optical characterization of Ni-TiO2 thin films as potential photocatalytic material

NASA Astrophysics Data System (ADS)

De, Rajnarayan; Haque, S. Maidul; Tripathi, S.; Rao, K. Divakar; Singh, Ranveer; Som, T.; Sahoo, N. K.

2017-09-01

Along with other transition metal doped titanium dioxide materials, Ni-TiO2 is considered to be one of the most efficient materials for catalytic applications due to its suitable energy band positions in the electronic structure. The present manuscript explores the possibility of improving the photocatalytic activity of RF magnetron sputtered Ni-TiO2 films upon heat treatment. Optical, structural and morphological and photocatalytic properties of the films have been investigated in detail for as deposited and heat treated samples. Evolution of refractive index (RI) and total film thickness as estimated from spectroscopic ellipsometry characterization are found to be in agreement with the trend in density and total film thickness estimated from grazing incidence X-ray reflectivity measurement. Interestingly, the evolution of these macroscopic properties were found to be correlated with the corresponding microstructural modifications realized in terms of anatase to rutile phase transformation and appearance of a secondary phase namely NiTiO3 at high temperature. Corresponding morphological properties of the films were also found to be temperature dependent which leads to modifications in the grain structure. An appreciable reduction of optical band gap from 2.9 to 2.5 eV of Ni-TiO2 thin films was also observed as a result of post deposition heat treatment. Testing of photocatalytic activity of the films performed under UV illumination demonstrates heat treatment under atmospheric ambience to be an effective means to enhance the photocatalytic efficiency of transition metal doped titania samples.

Structure and optical properties of TiO2 thin films deposited by ALD method

NASA Astrophysics Data System (ADS)

Szindler, Marek; Szindler, Magdalena M.; Boryło, Paulina; Jung, Tymoteusz

2017-12-01

This paper presents the results of study on titanium dioxide thin films prepared by atomic layer deposition method on a silicon substrate. The changes of surface morphology have been observed in topographic images performed with the atomic force microscope (AFM) and scanning electron microscope (SEM). Obtained roughness parameters have been calculated with XEI Park Systems software. Qualitative studies of chemical composition were also performed using the energy dispersive spectrometer (EDS). The structure of titanium dioxide was investigated by X-ray crystallography. A variety of crystalline TiO2 was also confirmed by using the Raman spectrometer. The optical reflection spectra have been measured with UV-Vis spectrophotometry.

Structural and optical investigation on the wings of Idea malabarica (Moore, 1877).

PubMed

Sackey, Juliet; Nuru, Zebib Y; Sone, Bertrand Tumbain; Maaza, Malik

2017-02-01

The nanostructures on the wings of Idea malabarica (Moore, 1877) were analysed using scanning electron microscopy, energy dispersive X-ray spectroscopy, atomic force microscopy, Fourier transform-infrared spectroscopy, and reflectance measurements. The chemical and morphological analyses revealed the chitin-based intricate nanostructures. The influence of the nanostructures on the wetting characteristics of the wing was investigated using optical imaging. Applying the Maxwell-Garnet approximation to the porosities within the nanostructures, the refractive indices, which relate the reflectance response, were estimated. It was concluded that the colour seen on the wings of the Idea malabarica originate from the nanostructural configurations of the chitin-based structures and the embedded pigment.

Optical and Luminescence Properties of β-NaFeO2 Nanoparticles

NASA Astrophysics Data System (ADS)

Singh, Sarbjit; Tangra, Ankush Kumar; Lotey, Gurmeet Singh

2018-05-01

β-NaFeO2 nanoparticles have been synthesized by sol-gel method and their morphological, structural and optical properties investigated. Transmission electron microscope study reveals that the size of the synthesis nanoparticles is 37 nm and they are possessing spherical symmetry. X-ray diffraction pattern shows the orthorhombic crystal structure of nanoparticles with space group Pn21 a. UV-visible spectra of β-NaFeO2 divulges that these nanoparticles have direct band gap 2.35 eV. The observed Fourier transform infrared spectroscopy spectra confirms the presence of Fe-Na bonding at 1074 cm-1. The photoluminescence study of these nanoparticles shows that these nanoparticles possesses various transition in the visible spectrum.

Structural, optical and Carrier dynamics of self-assembled InGaN nanocolumns on Si(111)

NASA Astrophysics Data System (ADS)

Kumar, Praveen; Devi, Pooja; Soto Rodriguez, P. E. D.; Jain, Rishabh; Jaggi, Neena; Sinha, R. K.; Kumar, Mahesh

2018-05-01

We investigated the morphological, structural, optical, electrical and carrier relaxation dynamic changes on the self-assembled grown InGaN nanocolumns (NCs) directly on p-Si(111) substrate at two different substrate temperature, namely 580 °C (A) and 500 °C (B). The emission wavelength of comparably low temperature (LT) grown NCs was red-shifted from 3.2eV to 2.4eV. First observations on the charge carrier dynamics of these directly grown NCs show comparable broad excited state absorption (ESA) for LT gown NCs, which manifest bi-exponential decay due to the radiative defects generated during the coalescence of these NCs.

Analysis of dispersion relation in three-dimensional single gyroid

NASA Astrophysics Data System (ADS)

Jheng, Pei-Lun; Hung, Yu-Chueh

2016-03-01

Gyroid is a type of three-dimensional chiral structures and has been found in many insect species. Besides the photonic crystal properties exhibited by gyroid structures, the chirality and gyroid network morphology also provide unique opportunities for manipulating propagation of light. In this work, we present studies based on finite-difference time domain (FDTD) method for analyzing the dispersion relation characteristics of dielectric single gyroid (SG) metamaterials. The band structures, transmission spectrum, dispersion surfaces, equifrequency contours (EFCs) of SG metamaterials are examined. Some interesting wave guiding characteristics, such as negative refraction and collimation, are presented and discussed. We also show how these optical properties are predicted by analyzing the EFCs at different frequencies. These results are crucial for the design of functional devices at optical frequencies based on dielectric single gyroid metamaterials.

Characterization on RF magnetron sputtered niobium pentoxide thin films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Usha, N.; Sivakumar, R., E-mail: krsivakumar1979@yahoo.com; Sanjeeviraja, C.

2014-10-15

Niobium pentoxide (Nb{sub 2}O{sub 5}) thin films with amorphous nature were deposited on microscopic glass substrates at 100°C by rf magnetron sputtering technique. The effect of rf power on the structural, morphological, optical, and vibrational properties of Nb{sub 2}O{sub 5} films have been investigated. Optical study shows the maximum average transmittance of about 87% and the optical energy band gap (indirect allowed) changes between 3.70 eV and 3.47 eV. AFM result indicates the smooth surface nature of the samples. Photoluminescence measurement showed the better optical quality of the deposited films. Raman spectra show the LO-TO splitting of Nb-O stretching ofmore » Nb{sub 2}O{sub 5} films.« less

Lunar and Planetary Science Conference, 9th, Houston, Tex., March 13-17, 1978, Proceedings. Volume 3 - The moon and the inner solar system

NASA Technical Reports Server (NTRS)

Merrill, R. B.

1978-01-01

Consideration is given to optical, X-ray, and gamma ray remote sensing of the moon. Papers are also presented on such aspects of lunar science as magnetic and electrical properties, morphology, volcanoes, structure and tectonics, seismology, and craters.

Synthesis and characterization of spin-coated ZnS thin films

NASA Astrophysics Data System (ADS)

Zaman, M. Burhanuz; Chandel, Tarun; Dehury, Kshetramohan; Rajaram, P.

2018-05-01

In this paper, we report synthesis of ZnS thin films using a sol-gel method. A unique aprotic solvent, dimethlysulphoxide (DMSO) has been used to obtain a homogeneous ZnS gel. Zinc acetate and thiourea were used as the precursor sources for Zn and S, respectively, to deposit nanocrystalline ZnS thin films. Optical, structural and morphological properties of the films were studied. Optical studies reveal high transmittance of the samples over the entire visible region. The energy band gap (Eg) for the ZnS thin films is found to be about 3.6 eV which matches with that of bulk ZnS. The interference fringes in transmissions spectrum show the high quality of synthesized samples. Strong photoluminescence peak in the UV region makes the films suitable for optoelectronic applications. X-ray diffraction studies reveal that sol-gel derived ZnS thin films are polycrystalline in nature with hexagonal structure. SEM studies confirmed that the ZnS films show smooth and uniform grains morphology having size in 20-25 nm range. The EDAX studies confirmed that the films are nearly stoichiometric.

2D double-layer-tube-shaped structure Bi2S3/ZnS heterojunction with enhanced photocatalytic activities

NASA Astrophysics Data System (ADS)

Gao, Xiaoming; Wang, Zihang; Fu, Feng; Li, Xiang; Li, Wenhong

2015-10-01

Bi2S3/ZnS heterojunction with 2D double-layer-tube-shaped structures was prepared by the facile synthesis method. The corresponding relationship was obtained among loaded content to phase, morphology, and optical absorption property of Bi2S3/ZnS composite. The results shown that Bi2S3 loaded could evidently change the crystallinity of ZnS, enhance the optical absorption ability for visible light of ZnS, and improve the morphologies and microstructure of ZnS. The photocatalytic activities of the Bi2S3/ZnS sample were evaluated for the photodegradation of phenol and desulfurization of thiophene under visible light irradiation. The results showed that Bi2S3 loaded greatly improved the photocatalytic activity of ZnS, and the content of loaded Bi2S3 had an impact on the catalytic activity of ZnS. Moreover, the mechanism of enhanced photocatalytic activity was also investigated by analysis of relative band positions of Bi2S3 and ZnS, and photo-generated hole was main active radicals during photocatalytic oxidation process.

Study on the Structural, Morphological and Optical Properties of RF-Sputtered Dysprosium-Doped Barium Tungstate Thin Films

NASA Astrophysics Data System (ADS)

Hridya, S.; Kavitha, V. S.; Chalana, S. R.; Reshmi Krishnan, R.; Sreeja Sreedharan, R.; Suresh, S.; Nampoori, V. P. N.; Sankararaman, S.; Prabhu, Radhakrishna; Mahadevan Pillai, V. P.

2017-11-01

Barium tungstate films with different Dy3+ doping concentrations, namely 0 wt.%, 1 wt.%, 3 wt.% and 5 wt.%, are deposited on cleaned quartz substrate by radio frequency magnetron sputtering technique and the prepared films are annealed at a temperature of 700°C. The structural, morphological and optical properties of the annealed films are studied using techniques such as x-ray diffraction (XRD), micro-Raman spectroscopy, field emission scanning electron microscopy, atomic force microscopy and photoluminescence spectroscopy. XRD analysis shows that all the films are well-crystallized in nature with a monoclinic barium tungstate phase. The presence of characteristic modes of the tungstate group in the Raman spectra supports the formation of the barium tungstate phase in the films. Scanning electron microscopic images of the films present a uniform dense distribution of well-defined grains with different sizes. All the doped films present a broad emission in the 390-500 nm region and its intensity increases up to 3 wt.% and thereafter decreases due to usual concentration quenching.

Self-organization of colloidal PbS quantum dots into highly ordered superlattices.

PubMed

Baranov, Alexander V; Ushakova, Elena V; Golubkov, Valery V; Litvin, Aleksandr P; Parfenov, Peter S; Fedorov, Anatoly V; Berwick, Kevin

2015-01-13

X-ray structural analysis, together with steady-state and transient optical spectroscopy, is used for studying the morphology and optical properties of quantum dot superlattices (QDSLs) formed on glass substrates by the self-organization of PbS quantum dots with a variety of surface ligands. The diameter of the PbS QDs varies from 2.8 to 8.9 nm. The QDSL's period is proportional to the dot diameter, increasing slightly with dot size due to the increase in ligand layer thickness. Removal of the ligands has a number of effects on the morphology of QDSLs formed from the dots of different sizes: for small QDs the reduction in the amount of ligands obstructs the self-organization process, impairing the ordering of the QDSLs, while for large QDs the ordering of the superlattice structure is improved, with an interdot distance as low as 0.4 nm allowing rapid charge carrier transport through the QDSLs. QDSL formation does not induce significant changes to the absorption and photoluminescence spectra of the QDs. However, the luminescence decay time is reduced dramatically, due to the appearance of nonradiative relaxation channels.

Synthesis of Novel Sea-Urchin-Like CdS and Their Optical Properties.

PubMed

Kamran, Muhammad Arshad; Liu, Ruibin; Shi, Li-Jie; Bukhtiar, Arfan; Li, Jing; Zou, Bingsuo

2015-06-01

A novel morphology of CdS sea-urchin-like microstructures is synthesized by simple thermal evaporation process. Microstructures with average size of 20-50 μm are composed of single crystalline CdS nanobelts. The structural, compositional, morphological characterization of the product were examined by X-ray diffraction, energy dispersive X-ray spectroscopy, Raman spectroscopy, scanning electron microscope, transmission electron microscopy and selected area electron diffraction while optical properties are investigated by Photoluminescence spectroscopy and time-resolved Photoluminescence measurements. The tentative growth mechanism for the growth of sea-urchin-like CdS is proposed and described briefly. A strong green emission with a maximum around 517 nm was observed from the individual CdS microstructure at room temperature, which was attributed to band-edge emission of CdS. These Novel structures exhibit excellent lasing (stimulated emission) with low threshold (9.07 μJ cm(-2)) at room temperature. We analyze the physical mechanism of stimulated emission. These results are important in the design of green luminescence, low-threshold laser and display devices in the future.

Structural, morphological and optical investigations on electron-beam irradiated PbF2-TeO2-B2O3-Eu2O3 glasses

NASA Astrophysics Data System (ADS)

Wagh, Akshatha; Petwal, Vikash; Dwivedi, Jishnu; Upadhyaya, V.; Raviprakash, Y.; Kamath, Sudha D.

2016-09-01

Combined structural, optical and morphological studies were carried out on Eu2O3 doped PbF2-TeO2-B2O3 glass samples, before and after being subjected to electron beam of energy 7.5 MeV. XRD confirmed the amorphous nature of the glasses even after 150 kGy electron beam irradiation. Densities of the irradiated samples showed slightly greater values when compared to their respective values before irradiation, which proved the increase in the compaction of the network. The intensities of the three prominent bands; B-O-B linkages, BO4 units and BO3 units of FT-IR spectra, of the titled glasses, showed slight decrease after electron beam irradiation. The decrement in the values of energy band gap and shift in cut-off wavelength towards red edge, proved the formation of color centers in the glass network after irradiation. The change in Hunter L values, through color measurement was a proof for the Farbe/color/absorption centers created in the glass sites after irradiation.

Fabrication and characterization of the noble metal nanostructures on the GaAs surface

NASA Astrophysics Data System (ADS)

Gladskikh, Polina V.; Gladskikh, Igor A.; Toropov, Nikita A.; Vartanyan, Tigran A.

2016-04-01

Self-assembled silver, gold, and copper nanostructures on the monocrystalline GaAs (100) wafer surface were obtained via physical vapor deposition and characterized by optical reflection spectroscopy, scanning electron microscopy, and current-voltage curve measurements. Reflection spectra of the samples with Ag equivalent thicknesses of 2, 5, 7.5, and 10 nm demonstrated wide plasmonic bands in the visible range of spectra. Thermal annealing of the nanostructures led to narrowing of the plasmonic bands of Au and Ag nanostructures caused by major transformations of the film morphology. While the as prepared films predominantly had a small scale labyrinth structure, after annealing well-separated nanoislands are formed on the gallium arsenide surface. A clear correlation between films morphology and their optical and electrical properties is elucidated. Annealing of the GaAs substrate with Ag nanostructures at 100 °C under control of the resistivity allowed us to obtain and fix the structure at the percolation threshold. It is established that the samples at the percolation threshold possess the properties of resistance switching and hysteresis.

Method for Estimating Bilirubin Isomerization Efficiency in Phototherapy to Treat Neonatal Jaundice

NASA Astrophysics Data System (ADS)

Lisenko, S. A.; Kugeiko, M. M.

2014-11-01

We propose a method for quantitative assessment of the efficacy of phototherapy to treat neonatal jaundice using the diffuse reflectance spectrum for the newborn's skin, based on the analytical dependence of the measured spectrum on the structural and morphological parameters of the skin, affecting the optical conditions in the medium, and an algorithm for rapid calculation of the bilirubin photoisomerization rate in the skin tissues as a function of the structural and morphological parameters of the skin and the wavelength of the exciting radiation. From the results of a numerical simulation of the process of radiation transport in the skin, we assess the stability of our method to variations in the scattering properties of the skin and the concentrations of its optically active chromophores (melanin, oxyhemoglobin, deoxyhemoglobin). We show that in order to achieve the maximum efficacy of phototherapy, we should use light from the range 484-496 nm. In this case, the intensity of the exciting radiation should be selected individually for each newborn according to the bilirubin photoisomerization rate characteristic for it.

Effect of annealing atmosphere on properties of Cu2ZnSn(S,Se)4 thin films

NASA Astrophysics Data System (ADS)

Xue, Yuming; Yu, Bingbing; Li, Wei; Feng, Shaojun; Wang, Yukun; Huang, Shengming; Zhang, Chao; Qiao, Zaixiang

2017-12-01

Earth-abundant Cu2ZnSn(S,Se)4(CZTSSe) thin film photovoltaic absorber layers were fabricated by co-evaporated Cu, ZnS, SnS and Se sources in a vacuum chamber followed by annealing at tubular furnace for 30 min at 550 °C. In this paper, we investigated the metal elements with stoichiometric ratio film to study the effect of annealing conditions of Se, SnS + Se, S and SnS + S atmosphere on the structure, surface morphological, optical and electrical properties of Cu2ZnSn(S,Se)4 thin films respectively. These films were characterized by Inductively Coupled Plasma-Mass Spectrometer, scanning electron microscopy, X-ray diffraction to investigate the composition, morphological and crystal structural properties. The grain size of samples were found to increase after annealing. XRD patterns confirmed the formation of pure polycrystalline CZTSSe thin films at S atmosphere, the optical band gaps are 1.02, 1.05, 1.23, 1.35 eV for Se, SnS + Se, SnS + S and S atmosphere respectively.

Structural, morphological, and optical characterizations of Mo, CrN and Mo:CrN sputtered coatings for potential solar selective applications

NASA Astrophysics Data System (ADS)

Ibrahim, Khalil; Mahbubur Rahman, M.; Taha, Hatem; Mohammadpour, Ehsan; Zhou, Zhifeng; Yin, Chun-Yang; Nikoloski, Aleksandar; Jiang, Zhong-Tao

2018-05-01

Mo, CrN, and Mo:CrN sputtered coatings synthesized onto silicon Si(100) substrates were investigated as solar selective surfaces and their potential applications in optical devices. These coatings were characterized using XRD, SEM, UV-vis, and FTIR techniques. XRD investigation, showed a change in CrN thin film crystallite characteristic due to Mo doping. Compared to the CrN coating, the Mo:CrN film has a higher lattice parameter and lower grain size of 4.19 nm and 106.18 nm, respectively. FESEM morphology confirmed the decrement in Mo:CrN crystal size due to Mo doping. Optical analysis showed that in the visible range of the solar spectrum, the CrN coatings exhibit the highest solar absorptance of 66% while the lowest thermal emittance value of 5.67 was recorded for the CrN coating doped with Mo. Consequently, the highest solar selectivity of 9.6, and the energy band-gap of 2.88 eV were achieved with the Mo-doped CrN coatings. Various optical coefficients such as optical absorption coefficient, refractive index, extinction coefficient, real and imaginary parts of dielectric constants, and energy loss functions of these coatings were also estimated from the optical reflectance data recorded in the wavelength range of 190-2300 nm.

Detecting cell death with optical coherence tomography and envelope statistics

NASA Astrophysics Data System (ADS)

Farhat, Golnaz; Yang, Victor X. D.; Czarnota, Gregory J.; Kolios, Michael C.

2011-02-01

Currently no standard clinical or preclinical noninvasive method exists to monitor cell death based on morphological changes at the cellular level. In our past work we have demonstrated that quantitative high frequency ultrasound imaging can detect cell death in vitro and in vivo. In this study we apply quantitative methods previously used with high frequency ultrasound to optical coherence tomography (OCT) to detect cell death. The ultimate goal of this work is to use these methods for optically-based clinical and preclinical cancer treatment monitoring. Optical coherence tomography data were acquired from acute myeloid leukemia cells undergoing three modes of cell death. Significant increases in integrated backscatter were observed for cells undergoing apoptosis and mitotic arrest, while necrotic cells induced a decrease. These changes appear to be linked to structural changes observed in histology obtained from the cell samples. Signal envelope statistics were analyzed from fittings of the generalized gamma distribution to histograms of envelope intensities. The parameters from this distribution demonstrated sensitivities to morphological changes in the cell samples. These results indicate that OCT integrated backscatter and first order envelope statistics can be used to detect and potentially differentiate between modes of cell death in vitro.

Synthesis, structural, optical and morphological characterization of hematite through the precipitation method: Effect of varying the nature of the base

NASA Astrophysics Data System (ADS)

Lassoued, Abdelmajid; Lassoued, Mohamed Saber; Dkhil, Brahim; Gadri, Abdellatif; Ammar, Salah

2017-08-01

Iron oxide (α-Fe2O3) nanoparticles were synthesized using the precipitation synthesis method focusing only on (FeCl3, 6H2O), NaOH, KOH and NH4OH as raw materials. The impact of varying the nature of the base on the crystalline phase, size and morphology of α-Fe2O3 products was explored. XRD spectra revealed that samples crystallize in the rhombohedral (hexagonal) system at 800 °C.The Transmission Electron Microscopy (TEM) and Scanning Electron Microscopy (SEM) were used to detect the morphology of synthesized nanoparticles and specify their sizes. However, the Fourier Transform Infra-Red (FT-IR) spectroscopy has permitted the observation of vibration band Fe-O. Raman spectroscopy was used not only to prove that we have synthesized hematite but also to identify their phonon modes. The Thermo Gravimetric Analysis (TGA) findings allow the thermal cycle determination of samples whereas Differential Thermal Analysis (DTA) findings allow the phase transition temperature identification. Besides, the optical investigation revealed that samples have an optical gap of about 2.1 eV. Findings highlight that the nature of the agent precipitant plays a significant role in the morphology of the products and the formation of the crystalline phase. Hematite synthesis with the base NH4OH brought about much stronger, sharper and wider diffraction peaks of α-Fe2O3. The morphology of samples are spherical with a size of about 61 nm while the size of the nanoparticles of hematite which we have synthesized with NaOH and KOH is respectively of the order of 82 and 79 nm.

Interactions of Small-Scale Physical Mixing Processes with the Structure, Morphology and Bloom Dynamics and Optics of Non-Spheroid Phytoplankton

DTIC Science & Technology

2001-09-30

microscopic imaging techniques, and microscopic video- cinematography protocols for both phytoplankton and zooplankton for use in current laboratory...phytoplankton, zooplankton and bioluminescence papers, and examined data/figures for layered structures. Imaging and Cinematography : Off-the-shelf...to preview it as a work-in-progress, email me (jrines@gso.uri.edu), and I will provide you with a temporary URL. Imaging and Cinematography

Magnesium Nanoparticles for Hydrogen Storage: Structure, Kinetics and Thermodynamics

NASA Astrophysics Data System (ADS)

Pasquini, L.; Brighi, M.; Montone, A.; Vittori Antisari, M.; Dam, B.; Palmisano, V.; Bonetti, E.

2012-08-01

Magnesium nanoparticles coated by a native oxide shell and decorated by palladium clusters were synthesized by the inert gas condensation technique. The kinetics and thermodynamics of hydrogen sorption were investigated by Sieverts measurements at high temperature and by optical hydrogenography close to ambient temperature. The structure and morphology of the nanoparticles were studied by electron microscopy and X-ray diffraction both in the as-prepared state and after hydrogen sorption cycles.

Substrate dependent hierarchical structures of RF sputtered ZnS films

NASA Astrophysics Data System (ADS)

Chalana, S. R.; Mahadevan Pillai, V. P.

2018-05-01

RF magnetron sputtering technique was employed to fabricate ZnS nanostructures with special emphasis given to study the effect of substrates (quartz, glass and quartz substrate pre-coated with Au, Ag, Cu and Pt) on the structure, surface evolution and optical properties. Type of substrate has a significant influence on the crystalline phase, film morphology, thickness and surface roughness. The present study elucidates the suitability of quartz substrate for the deposition of stable and highly crystalline ZnS films. We found that the role of metal layer on quartz substrate is substantial in the preparation of hierarchical ZnS structures and these structures are of great importance due to its high specific area and potential applications in various fields. A mechanism for morphological evolution of ZnS structures is also presented based on the roughness of substrates and primary nonlocal effects in sputtering. Furthermore, the findings suggest that a controlled growth of hierarchical ZnS structures may be achieved with an ordinary RF sputtering technique by changing the substrate type.

The polarization response in InAs quantum dots: theoretical correlation between composition and electronic properties.

PubMed

Usman, Muhammad; Tasco, Vittorianna; Todaro, Maria Teresa; De Giorgi, Milena; O'Reilly, Eoin P; Klimeck, Gerhard; Passaseo, Adriana

2012-04-27

III-V growth and surface conditions strongly influence the physical structure and resulting optical properties of self-assembled quantum dots (QDs). Beyond the design of a desired active optical wavelength, the polarization response of QDs is of particular interest for optical communications and quantum information science. Previous theoretical studies based on a pure InAs QD model failed to reproduce experimentally observed polarization properties. In this work, multi-million atom simulations are performed in an effort to understand the correlation between chemical composition and polarization properties of QDs. A systematic analysis of QD structural parameters leads us to propose a two-layer composition model, mimicking In segregation and In-Ga intermixing effects. This model, consistent with mostly accepted compositional findings, allows us to accurately fit the experimental PL spectra. The detailed study of QD morphology parameters presented here serves as a tool for using growth dynamics to engineer the strain field inside and around the QD structures, allowing tuning of the polarization response.

Noninvasive imaging of oral mucosae with optical coherence tomography

NASA Astrophysics Data System (ADS)

Lee, Cheng-Yu; Chen, Wei-Chuan; Tsai, Meng-Tsan

2017-04-01

In this study, a swept-source optical coherence tomography (OCT) system is developed for in vivo visualization of structural and vascular morphology oral mucosa. For simplification of optical probe fabrication, probe weight, and system setup, the body of the scanning probe is fabricated by a 3D printer to fix the optical components and the mechanical scanning device, and a partially reflective slide is attached at the output end of probe to achieve a common-path configuration. Aside from providing the ability of 3D structural imaging with the developed system, 3D vascular images of oral mucosa can be simultaneously obtained. Then, different locations of oral mucosa are scanned with common-path OCT. The results show that epithelium and lamina propria layers as well as fungiform papilla can be identified and microvascular images can be acquired. With the proposed probe, the system cost and volume can be greatly reduced. Experimental results indicate that such common-path OCT system could be further implemented for oral cancer diagnosis.

Effect of RE (Nd3+, Sm3+) oxide on structural, optical properties of Na2O-Li2O-ZnO-B2O3 glass system

NASA Astrophysics Data System (ADS)

Hivrekar, Mahesh M.; Bhoyar, D. N.; Mande, V. K.; Dhole, V. V.; Solunke, M. B.; Jadhav, K. M.

2018-05-01

Zinc borate glass activated with rare earth oxide (Nd2O3, Sm2O3) of Na2O-Li2O-ZnO-B2O3 quaternary system has been prepared successfully by melt quenching method. The nucleation and growth of RE oxide were controlled temperature range 950-1000° C and rapid cooling at room temperature. The physical, structural and optical properties were characterized by using X-ray diffraction (XRD), SEM, Ultraviolet-visible spectroscopy (UV-Vis). XRD and SEM studies confirmed the amorphous nature, surface morphology of prepared zinc borate glass. The physical parameters like density, molar volume, molar mass of Nd3+, Sm3+ doped borate glass are summarized in the present article. The optical absorption spectra along with tauc's plot are presented. The optical energy band gap increases due to the addition of rare earth oxide confirming the role of network modifier.

Morphology-controllable of Sn doped ZnO nanorods prepared by spray pyrolysis for transparent electrode application

NASA Astrophysics Data System (ADS)

Hameed, M. Shahul; Princice, J. Joseph; Babu, N. Ramesh; Zahirullah, S. Syed; Deshmukh, Sampat G.; Arunachalam, A.

2018-05-01

Transparent conductive Sn doped ZnO nanorods have been deposited at various doping level by spray pyrolysis technique on glass substrate. The structural, surface morphological and optical properties of these films have been investigated with the help of X-ray diffraction (XRD), scanning electron microscope (SEM), atomic force microscope (AFM) and UV-Vis spectrophotometer respectively. XRD patterns revealed a successful high quality growth of single crystal ZnO nanorods with hexagonal wurtzite structure having (002) preferred orientation. The scanning electron microscope (SEM) image of the prepared films exposed the uniform distribution of Sn doped ZnO nanorod shaped grains. All these films were highly transparent in the visible region with average transmittance of 90%.

Structural and morphological study of chemically synthesized CdSe thin films

NASA Astrophysics Data System (ADS)

Agrawal, P.; Singh, Randhir; Sharma, Jeewan; Sachdeva, M.; Singh, Anupinder; Bhargava, A.

2018-05-01

Nanocrystalline CdSe thin films were prepared by Chemical Bath Deposition (CBD) method using potassium nitrilo-triacetic acid cadmium complex and sodium selenosulphite. The as deposited films were red in color, uniform and well adherent to the glass substrate. These films were strongly dependent on the deposition parameters such as bath composition, deposition temperature and time. Films were annealed at 350 °C for four hours. The morphological, structural and optical properties were studied using X-ray diffraction (XRD), UV-VIS spectrophotometer measurements, scanning electron microscopy and atomic force microscopy. The XRD analysis confirmed that films are predominantly in hexagonal phase. Scanning electron micrograph shows that the grains are uniformly spread all over the film and each grain contains many nanocrystals with spherical shapes.

Evolution of weld metal microstructure in shielded metal arc welding of X70 HSLA steel with cellulosic electrodes: A case study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ghomashchi, Reza, E-mail: reza.ghomashchi@adelaide.edu.au; Costin, Walter; Kurji, Rahim

2015-09-15

The microstructure of weld joint in X70 line pipe steel resulted from shielded metal arc welding with E6010 cellulosic electrodes is characterized using optical and electron microscopy. A range of ferritic morphologies have been identified ranging from polygonal inter- and intra-prior austenite grains allotriomorphic, idiomorphic ferrites to Widmanstätten, acicular and bainitic ferrites. Electron Backscatter Diffraction (EBSD) analysis using Image Quality (IQ) and Inverse Pole Figure (IPF) maps through superimposition of IQ and IPF maps and measurement of percentages of high and low angle grain boundaries was identified to assist in differentiation of acicular ferrite from Widmanstätten and bainitic ferrite morphologies.more » In addition two types of pearlitic structures were identified. There was no martensite detected in this weld structure. The morphology, size and chemistry of non-metallic inclusions are also discussed briefly. - Highlights: • Application of EBSD reveals orientation relationships in a range of phases for shielded metal arc welding of HSLA steel. • Nucleation sites of various ferrite morphologies identified • Formation of upper and lower bainite and their morphologies.« less

Electrical and optical properties of molybdenum doped zinc oxide films prepared by reactive RF magnetron sputtering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Reddy, R. Subba; Sreedhar, A.; Uthanna, S., E-mail: uthanna@rediffmail.com

Molybdenum doped zinc oxide (MZO) films were deposited on to glass substrates held at temperatures in the range from 303 to 673 K by reactive RF magnetron sputtering method. The chemical composition, crystallographic structure and surface morphology, electrical and optical properties of the films were determined. The films contained the molybdenum of 2.7 at. % in ZnO. The films deposited at 303 K were of X-ray amorphous. The films formed at 473 K were of nanocrystalline in nature with wurtzite structure. The crystallite size of the films was increased with the increase of substrate temperature. The optical transmittance of the films was inmore » the visible range was 80–85%. The molybdenum (2.7 at %) doped zinc oxide films deposited at substrate temperature of 573 K were of nanocrystalline with electrical resistivity of 7.2×10{sup −3} Ωcm, optical transmittance of 85 %, optical band gap of 3.35 eV and figure of merit 30.6 Ω{sup −1}cm{sup −1}.« less

Darkening effect on AZ31B magnesium alloy surface induced by nanosecond pulse Nd:YAG laser

NASA Astrophysics Data System (ADS)

Guan, Y. C.; Zhou, W.; Zheng, H. Y.; Li, Z. L.

2013-09-01

Permanent darkening effect was achieved on surface of AZ31B Mg alloy irradiated with nanosecond pulse Nd:YAG laser, and special attention was made to examine how surface structure as well as oxidation affect the darkening effect. Experiments were carried out to characterize morphological evolution and chemical composition of the irradiated areas by optical reflection spectrometer, Talysurf surface profiler, SEM, EDS, and XPS. The darkening effect was found to be occurred at the surface under high laser energy. Optical spectra showed that the induced darkening surface was uniform over the spectral range from 200 nm to 1100 nm. SEM and surface profiler showed that surface morphology of darkening areas consisted of large number of micron scale cauliflower-like clusters and protruding particles. EDS and XPS showed that compared to non-irradiated area, oxygen content at the darkening areas increased significantly. It was proposed a mechanism that involved trapping of light in the surface morphology and chemistry variation of irradiated areas to explain the laser-induced darkening effect on AZ31B Mg alloy.

Room-temperature wide-range luminescence and structural, optical, and electrical properties of SILAR deposited Cu-Zn-S nano-structured thin films

NASA Astrophysics Data System (ADS)

Jose, Edwin; Kumar, M. C. Santhosh

2016-09-01

We report the deposition of nanostructured Cu-Zn-S composite thin films by Successive Ionic Layer Adsorption and Reaction (SILAR) method on glass substrates at room temperature. The structural, morphological, optical, photoluminescence and electrical properties of Cu-Zn-S thin films are investigated. The results of X-ray diffraction (XRD) and Raman spectroscopy studies indicate that the films exhibit a ternary Cu-Zn-S structure rather than the Cu xS and ZnS binary composite. Scanning electron microscope (SEM) studies show that the Cu-Zn-S films are covered well over glass substrates. The optical band gap energies of the Cu-Zn-S films are calculated using UV-visible absorption measurements, which are found in the range of 2.2 to 2.32 eV. The room temperature photoluminescence studies show a wide range of emissions from 410 nm to 565 nm. These emissions are mainly due to defects and vacancies in the composite system. The electrical studies using Hall effect measurements show that the Cu-Zn-S films are having p-type conductivity.

Interfacial effect on the structural and optical properties of pure SnO2 and dual shells (ZnO; SiO2) coated SnO2 core-shell nanospheres for optoelectronic applications

NASA Astrophysics Data System (ADS)

Selvi, N.; Sankar, S.; Dinakaran, K.

2014-12-01

Nanocrystallites of SnO2 core and dual shells (ZnO, SiO2) coated SnO2 core-shell nanospheres were successfully synthesized by co-precipitation method. The as prepared and annealed samples were characterized by X-ray diffraction (XRD), Fourier Transform Infrared spectroscopy (FTIR), High resolution transmission electron microscopy (HRTEM) and UV-Vis analysis. XRD pattern confirms the obtained SnO2 core with tetragonal rutile crystalline structure and the shell ZnO with hexagonal structure. FTIR result shows the functional groups present in the samples. The spherical morphology and the formation of the core-shell structures have been confirmed by HRTEM measurements. The UV-Vis showed that band gap is red shifted for as-prepared and the shells coated core-shell samples. From this investigation it can be concluded that the surface modification with different metal and insulating oxides strongly influences the optical properties of the core-shell materials which enhance their potential applications towards optical devices fabrication.

Interaction of light with hematite hierarchical structures: Experiments and simulations

NASA Astrophysics Data System (ADS)

Distaso, Monica; Zhuromskyy, Oleksander; Seemann, Benjamin; Pflug, Lukas; Mačković, Mirza; Encina, Ezequiel; Taylor, Robin Klupp; Müller, Rolf; Leugering, Günter; Spiecker, Erdmann; Peschel, Ulf; Peukert, Wolfgang

2017-03-01

Mesocrystalline particles have been recognized as a class of multifunctional materials with potential applications in different fields. However, the internal organization of nanocomposite mesocrystals and its influence on the final properties have not yet been investigated. In this paper, a novel strategy based on electrodynamic simulations is developed to shed light on how the internal structure of mesocrystals influences their optical properties. In a first instance, a unified design protocol is reported for the fabrication of hematite/PVP particles with different morphologies such as pseudo-cubes, rods-like and apple-like structures and controlled particle size distributions. The optical properties of hematite/PVP mesocrystals are effectively simulated by taking their aggregate and nanocomposite structure into consideration. The superposition T-Matrix approach accounts for the aggregate nature of mesocrystalline particles and validate the effective medium approximation used in the framework of the Mie theory and electromagnetic simulation such as Finite Element Method. The approach described in our paper provides the framework to understand and predict the optical properties of mesocrystals and more general, of hierarchical nanostructured particles.

Polycrystalline BiFeO{sub 3} thin film synthesized via sol-gel assisted spin coating technique for photosensitive application

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bogle, K. A., E-mail: kashinath.bogle@gmail.com; Narwade, R. D.; Mahabole, M. P.

2016-05-06

We are reporting photosensitivity property of BiFeO{sub 3} thin film under optical illumination. The thin film used for photosensitivity work was fabricated via sol-gel assisted spin coating technique. I-V measurements on the Cu/BiFeO{sub 3}/Al structure under dark condition show a good rectifying property and show dramatic blue shit in threshold voltage under optical illumination. The microstructure, morphology and elemental analysis of the films were characterized by using XRD, UV-Vis, FTIR, SEM and EDS.

Optical properties of Mg doped p-type GaN nanowires

NASA Astrophysics Data System (ADS)

Patsha, Avinash; Pandian, Ramanathaswamy; Dhara, S.; Tyagi, A. K.

2015-06-01

Mg doped p-type GaN nanowires are grown using chemical vapor deposition technique in vapor-liquid-solid (VLS) process. Morphological and structural studies confirm the VLS growth process of nanowires and wurtzite phase of GaN. We report the optical properties of Mg doped p-type GaN nanowires. Low temperature photoluminescence studies on as-grown and post-growth annealed samples reveal the successful incorporation of Mg dopants. The as-grwon and annealed samples show passivation and activation of Mg dopants, respectively, in GaN nanowires.

Development of CdS Nanostructures by Thermal Decomposition of Aminocaproic Acid-Mixed Cd-Thiourea Complex Precursor: Structural, Optical and Photocatalytic Characterization.

PubMed

Patel, Jayesh D; Mighri, Frej; Ajji, Abdellah; Chaudhuri, Tapas K

2015-04-01

The present work deals with two different CdS nanostructures produced via hydrothermal and solvothermal decompositions of aminocaproic acid (ACA)-mixed Cd-thiourea complex precursor at 175 °C. Both nanostructures were extensively characterized for their structural, morphological and optical properties. The powder X-ray diffraction characterization showed that the two CdS nanostructures present a wurtzite morphology. Scanning electron microscopy and energy-dispersive X-ray characterizations revealed that the hydrothermal decomposition produced well-shaped CdS flowers composed of six dendritic petals, and the solvothermal decomposition produced CdS microspheres with close stoichiometric chemical composition. The UV-vis absorption and photoluminescence spectra of CdS dendritic flowers and microsphere nanostructures showed that both nanostructures present a broad absorption between 200 and 700 nm and exhibit strong green emissions at 576 and 520 nm upon excitations at 290 nm and 260 nm, respectively. The transmission electron microscopy (TEM) and Brunauer-Emmett-Teller (BET) characterizations confirmed that CdS microspheres were mesoporous and were composed of small nanocrystals. A possible growth mechanism in the formation of the CdS nanostructures was proposed based on morphology evolution as a function of the reaction time. Furthermore, the as-synthesized CdS nanostructures were found to exhibit highly efficient photocatalytic activities for the degradation of methyl orange (MeO) and rhodamine B (RhB) dyes.

Thin-film metal hydrides.

PubMed

Remhof, Arndt; Borgschulte, Andreas

2008-12-01

The goal of the medieval alchemist, the chemical transformation of common metals into nobel metals, will forever be a dream. However, key characteristics of metals, such as their electronic band structure and, consequently, their electric, magnetic and optical properties, can be tailored by controlled hydrogen doping. Due to their morphology and well-defined geometry with flat, coplanar surfaces/interfaces, novel phenomena may be observed in thin films. Prominent examples are the eye-catching hydrogen switchable mirror effect, the visualization of solid-state diffusion and the formation of complex surface morphologies. Thin films do not suffer as much from embrittlement and/or decrepitation as bulk materials, allowing the study of cyclic absorption and desorption. Therefore, thin-metal hydride films are used as model systems to study metal-insulator transitions, for high throughput combinatorial research or they may be used as indicator layers to study hydrogen diffusion. They can be found in technological applications as hydrogen sensors, in electrochromic and thermochromic devices. In this review, we discuss the effect of hydrogen loading of thin niobium and yttrium films as archetypical examples of a transition metal and a rare earth metal, respectively. Our focus thereby lies on the hydrogen induced changes of the electronic structure and the morphology of the thin films, their optical properties, the visualization and the control of hydrogen diffusion and on the study of surface phenomena and catalysis.

Replication of Leaf Surface Structures for Light Harvesting

PubMed Central

Huang, Zhongjia; Yang, Sai; Zhang, Hui; Zhang, Meng; Cao, Wei

2015-01-01

As one of the most important hosts of natural light harvesting, foliage normally has complicated surface structures to capture solar radiances. Bio-mimicking leaf surface structures can provide novel designs of covers in photovoltaic systems. In this article, we reported on replicating leaf surface structures on poly-(methyl methacrylate) polymers to prompt harvesting efficiencies. Prepared via a double transfer process, the polymers were found to have high optical transparencies and transmission hazes, with both values exceeding 80% in some species. Benefiting from optical properties and wrinkled surfaces, the biomimetic polymers brought up to 17% gains to photovoltaic efficiencies. Through Monte-Carlo simulations of light transport, ultrahigh haze values and low reflections were attributed to lightwave guidance schemes lead by the nano- and micro-morphologies which are inherited from master leaves. Thus, leaf surface bio-mimicking can be considered as a strategic direction to design covers of light harvesting systems. PMID:26381702

Process-Parameter-Dependent Optical and Structural Properties of ZrO2MgO Mixed-Composite Films Evaporated from the solid Solution

NASA Technical Reports Server (NTRS)

Sahoo, N. K.; Shapiro, A. P.

1998-01-01

The process-parameter-dependent optical and structural properties of ZrO2MgO mixed-composite material have been investigated. Optical properties were derived from spectrophotometric measurements. By use of atomic force microscopy, x-ray diffraction analysis, and energy-dispersive x-ray (EDX) analysis, the surface morphology, grain size distributions, crystallographic phases, and process-dependent material composition of films have been investigated. EDX analysis made evident the correlation between the oxygen enrichment in the films prepared at a high level of oxygen pressure and the very low refractive index. Since oxygen pressure can be dynamically varied during a deposition process, coatings constructed of suitable mixed-composite thin films can benefit from continuous modulation of the index of refraction. A step modulation approach is used to develop various multilayer-equivalent thin-film devices.

Structural characterization on in vitro porcine skin treated by ablative fractional laser using optical coherence tomography

NASA Astrophysics Data System (ADS)

Feng, Kairui; Zhou, Kanheng; Ling, Yuting; O'Mahoney, Paul; Ewan, Eadie; Ibbotson, Sally H.; Li, Chunhui; Huang, Zhihong

2018-02-01

Ablative fractional skin laser is widely applied for various skin conditions, especially for cosmetic repairing and promoting the located drug delivery. Although the influence of laser treatment over the skin has been explored before in means of excision and biopsy with microscopy, these approaches are invasive, only morphological and capable of distorting the skin. In this paper the authors use fresh porcine skin samples irradiated by the lasers, followed by detected by using Optical Coherence Tomography (OCT). This advanced optical technique has the ability to present the high resolution structure image of treated sample. The results shows that laser beams can produce holes left on the surface after the irradiation. The depth of holes can be affected by changes of laser energy while the diameter of holes have no corresponding relation. Plus, OCT, as a valuable imaging technology, is capable of monitoring the clinical therapy procedure and assisting the calibration.

Label-free imaging of the dynamics of cell-to-cell string-like structure bridging in the free-space by low-coherent quantitative phase microscopy

NASA Astrophysics Data System (ADS)

Yamauchi, Toyohiko; Iwai, Hidenao; Yamashita, Yutaka

2013-03-01

We succeeded in utilizing our low-coherent quantitative phase microscopy (LC-QPM) to achieve label-free and three-dimensional imaging of string-like structures bridging the free-space between live cells. In past studies, three dimensional morphology of the string-like structures between cells had been investigated by electron microscopies and fluorescence microscopies and these structures were called "membrane nanotubes" or "tunneling nanotubes." However, use of electron microscopy inevitably kills these cells and fluorescence microscopy is itself a potentially invasive method. To achieve noninvasive imaging of live cells, we applied our LC-QPM which is a reflection-type, phase resolved and full-field interference microscope employing a low-coherent light source. LC-QPM is able to visualize the three-dimensional morphology of live cells without labeling by means of low-coherence interferometry. The lateral (diffraction limit) and longitudinal (coherence-length) spatial resolution of LC-QPM were respectively 0.49 and 0.93 micrometers and the repeatability of the phase measurement was 0.02 radians (1.0 nm). We successfully obtained three-dimensional morphology of live cultured epithelial cells (cell type: HeLa, derived from cervix cancer) and were able to clearly observe the individual string-like structures interconnecting the cells. When we performed volumetric imaging, a 80 micrometer by 60 micrometer by 6.5 micrometer volume was scanned every 5.67 seconds and 70 frames of a three-dimensional movie were recorded for a duration of 397 seconds. Moreover, the optical phase images gave us detailed information about the three-dimensional morphology of the string-like structure at sub-wavelength resolution. We believe that our LC-QPM will be a useful tool for the study of three-dimensional morphology of live cells.

Generation of conductivity through transfer charge properties, for polyesters and polyamides with characteristic functional groups

NASA Astrophysics Data System (ADS)

Gonzalez, Carmen; Tagle, Luis Hernan; Terraza, Claudio A.; Barriga, Andres; Cabrera, A. L.; Volkmann, Ulrich G.

2011-03-01

Electro-optic properties of σ -conjugated polymers, as polysilylene; are associated with electron conjugation in the silicon atom, which allows a significant delocalization of electrons along of the chain. Thus, the conductivity is intimately connected to the mobility of charge carriers, which in turn depends on the structure and morphology of the system. We report the characterization of polyesters (PEFs) and polyamides (PAFs). Film thicknesses were obtained by ellipsometry. The vibration frequencies of the groups were determined by FT-IR and corroborated by Raman spectroscopy. Structural information was obtained from X-Ray diffraction (XRD). The structural and surface morphology were studied by scanning electron microscope (SEM). Electrical conductivity of the polymers was measured before and after exposure to iodine vapor, for films of different thicknesses. Morphological differentiation was studied by energy dispersive microscopy (EDX), showing a regular distribution of iodine within the polymer. Preliminary conductivity measurements showed adverse effects when oxidation of the polymer films is induced These effects are related to a certain grade of disorder within the system

Indium Doped Zinc Oxide Thin Films Deposited by Ultrasonic Chemical Spray Technique, Starting from Zinc Acetylacetonate and Indium Chloride

PubMed Central

Biswal, Rajesh; Maldonado, Arturo; Vega-Pérez, Jaime; Acosta, Dwight Roberto; Olvera, María De La Luz

2014-01-01

The physical characteristics of ultrasonically sprayed indium-doped zinc oxide (ZnO:In) thin films, with electrical resistivity as low as 3.42 × 10−3 Ω·cm and high optical transmittance, in the visible range, of 50%–70% is presented. Zinc acetylacetonate and indium chloride were used as the organometallic zinc precursor and the doping source, respectively, achieving ZnO:In thin films with growth rate in the order of 100 nm/min. The effects of both indium concentration and the substrate temperature on the structural, morphological, optical, and electrical characteristics were measured. All the films were polycrystalline, fitting well with hexagonal wurtzite type ZnO. A switching in preferential growth, from (002) to (101) planes for indium doped samples were observed. The surface morphology of the films showed a change from hexagonal slices to triangle shaped grains as the indium concentration increases. Potential applications as transparent conductive electrodes based on the resulting low electrical resistance and high optical transparency of the studied samples are considered. PMID:28788118

Melt growth of organic 4-(2-Phenylisopropyl) phenol single crystal and its structural, thermal, dielectric permittivity and optical properties

NASA Astrophysics Data System (ADS)

Sadhasivam, S.; Rajesh, N. P.

2017-12-01

A nonlinear optical (NLO) organic crystal 4-(2-Phenylisopropyl) phenol has been grown by a top seeded melt growth technique. The melt growth kinetics of solid-liquid (molten) interface and facets formation in melt growth were studied. The melt grown crystal has the (001), (00 1 bar),(110)(1 bar 1 bar 0) ,(1 bar 20),(1 2 bar 0),(2 bar 10) and(2 1 bar 0) different morphological face. The morphological characteristics of melt grown crystal helps to better infer the kinetic influence of melt and hone growth of organic material. The rhombohedral lattice cell parameters were measured by single crystal X-ray diffraction. 4-(2-Phenylisopropyl) phenol crystallizes in space group of R 3 bar . Thermal study shows that solid to liquid transition occurring at 350 K and decomposes at 597 K. The grown crystal was optically transparent in the wavelength range of 300-1100 nm. The low dielectric constant (9-11) was measured in the [001] of 4-(2-Phenylisopropyl) phenol crystal.

Plasmonic response in nanoporous metal: dependence on network topology

NASA Astrophysics Data System (ADS)

Galí, Marc A.; Tai, Matthew C.; Arnold, Matthew D.; Cortie, Michael B.; Gentle, Angus R.; Smith, Geoffrey B.

2015-12-01

The optical and electrical responses of open, nanoscale, metal networks are of interest in a variety of technologies including transparent conducting electrodes, charge storage, and surfaces with controlled spectral selectivity. The properties of such nanoporous structures depend on the shape and extent of individual voids and the associated hyper-dimensional connectivity and density of the metal filaments. Unfortunately, a quantitative understanding of this dependence is at present only poorly developed. Here we address this problem using numerical simulations applied to a systematically designed series of prototypical sponges. The sponges are produced by a Monte Carlo simulation of the dealloying of Ag-Al alloys containing from 60% to 85% Al. The result is a series of Ag sponges of realistic morphology. The optical properties of the sponges are then calculated by the discrete dipole approximation and the results used to construct an 'effective medium' model for each sponge. We show how the resulting effective medium can be correlated with the associated morphological characteristics of each target and how the optical properties are primarily controlled by the density of the sponge and its state of percolation.

Adaptive Optics Imaging Survey of Luminous Infrared Galaxies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Laag, E A; Canalizo, G; van Breugel, W

2006-03-13

We present high resolution imaging observations of a sample of previously unidentified far-infrared galaxies at z < 0.3. The objects were selected by cross-correlating the IRAS Faint Source Catalog with the VLA FIRST catalog and the HST Guide Star Catalog to allow for adaptive optics observations. We found two new ULIGs (with L{sub FIR} {ge} 10{sup 12} L{sub {circle_dot}}) and 19 new LIGs (with L{sub FIR} {ge} 10{sup 11} L{sub {circle_dot}}). Twenty of the galaxies in the sample were imaged with either the Lick or Keck adaptive optics systems in H or K{prime}. Galaxy morphologies were determined using the twomore » dimensional fitting program GALFIT and the residuals examined to look for interesting structure. The morphologies reveal that at least 30% are involved in tidal interactions, with 20% being clear mergers. An additional 50% show signs of possible interaction. Line ratios were used to determine powering mechanism; of the 17 objects in the sample showing clear emission lines--four are active galactic nuclei and seven are starburst galaxies. The rest exhibit a combination of both phenomena.« less

Indium Doped Zinc Oxide Thin Films Deposited by Ultrasonic Chemical Spray Technique, Starting from Zinc Acetylacetonate and Indium Chloride.

PubMed

Biswal, Rajesh; Maldonado, Arturo; Vega-Pérez, Jaime; Acosta, Dwight Roberto; De La Luz Olvera, María

2014-07-04

The physical characteristics of ultrasonically sprayed indium-doped zinc oxide (ZnO:In) thin films, with electrical resistivity as low as 3.42 × 10 -3 Ω·cm and high optical transmittance, in the visible range, of 50%-70% is presented. Zinc acetylacetonate and indium chloride were used as the organometallic zinc precursor and the doping source, respectively, achieving ZnO:In thin films with growth rate in the order of 100 nm/min. The effects of both indium concentration and the substrate temperature on the structural, morphological, optical, and electrical characteristics were measured. All the films were polycrystalline, fitting well with hexagonal wurtzite type ZnO. A switching in preferential growth, from (002) to (101) planes for indium doped samples were observed. The surface morphology of the films showed a change from hexagonal slices to triangle shaped grains as the indium concentration increases. Potential applications as transparent conductive electrodes based on the resulting low electrical resistance and high optical transparency of the studied samples are considered.

Development of structure in natural silk spinning and poly(vinyl alcohol) hydrogel formation

NASA Astrophysics Data System (ADS)

Willcox, Patricia Jeanene

This research involves the characterization of structure and structure formation in aqueous systems. Particularly, these studies investigate the effect of various processing variables on the structure formation that occurs upon conversion from aqueous solution to fiber or hydrogel. The two processes studied include natural silk fiber spinning and physical gelation of poly(vinyl alcohol), PVOH, in water. The techniques employed combine cryogenic technology for sample preparation and direct observation by transmission electron microscopy with electron diffraction, atomic force microscopy, optical rheometry, X-ray scattering and optical microscopy. In order to explore the full range of structure formation in natural silk spinning, studies are conducted in vivo and in vitro. In vivo structural investigations are accomplished through the cryogenic quenching and subsequent microtoming of live silk-spinning animals, Nephila clavipes (spider) and Bombyx mori (silkworm). Observations made using transmission electron microscopy, electron diffraction and atomic force microscopy indicate a cholesteric liquid crystalline mesophase of aqueous silk fibroin in both species. The mechanism of structure formation in solution is studied in vitro using optical rheometry on aqueous solutions made from regenerated Bombyx mori cocoon silk. Concentrated solutions exhibit birefringence under flow, with a wormlike conformation of the silk molecules in concentrated salt solution. Changes in salt concentration and pH of the aqueous silk solutions result in differing degrees of alignment and aggregation. These results suggest that structural control in the natural silk spinning process is accomplished by chemical manipulation of the electrostatic interactions and hydrogen bonding between chains. Application of cryogenic methods in transmission electron microscopy also provides a unique look at hydration-dependent structures in gels of poly(vinyl alcohol) produced by freeze-thaw processing. Morphologies ranging from circular pores to fibrillar networks are observed in gels formed from aqueous PVOH solutions subjected to cycles of freezing and thawing. These morphologies can be directly associated with the progressive nature of the mechanism of gelation as it proceeds from liquid-liquid phase separation to crystallization with increased cycling. A comparison of the structures produced by cycling and by aging suggests that there is a similarity in structural changes, but a superposition of the effects of cycling and aging is not possible.

Plasmonic Light Trapping in Thin-Film Solar Cells: Impact of Modeling on Performance Prediction

PubMed Central

Micco, Alberto; Pisco, Marco; Ricciardi, Armando; Mercaldo, Lucia V.; Usatii, Iurie; La Ferrara, Vera; Delli Veneri, Paola; Cutolo, Antonello; Cusano, Andrea

2015-01-01

We present a comparative study on numerical models used to predict the absorption enhancement in thin-film solar cells due to the presence of structured back-reflectors exciting, at specific wavelengths, hybrid plasmonic-photonic resonances. To evaluate the effectiveness of the analyzed models, they have been applied in a case study: starting from a U-shaped textured glass thin-film, µc-Si:H solar cells have been successfully fabricated. The fabricated cells, with different intrinsic layer thicknesses, have been morphologically, optically and electrically characterized. The experimental results have been successively compared with the numerical predictions. We have found that, in contrast to basic models based on the underlying schematics of the cell, numerical models taking into account the real morphology of the fabricated device, are able to effectively predict the cells performances in terms of both optical absorption and short-circuit current values.

Effect of silver thickness on structural, optical and morphological properties of nanocrystalline Ag/NiO thin films

NASA Astrophysics Data System (ADS)

Jalili, S.; Hajakbari, F.; Hojabri, A.

2018-03-01

Silver (Ag) nanolayers were deposited on nickel oxide (NiO) thin films by DC magnetron sputtering. The thickness of Ag layers was in range of 20-80 nm by variation of deposition time between 10 and 40 s. X-ray diffraction results showed that the crystalline properties of the Ag/NiO films improved by increasing the Ag film thickness. Also, atomic force microscopy and field emission scanning electron microscopy images demonstrated that the surface morphology of the films was highly affected by film thickness. The film thickness and the size of particles change by elevating the Ag deposition times. The composition of films was determined by Rutherford back scattering spectroscopy. The transmission of light was gradually reduced by augmentation of Ag films thickness. Furthermore; the optical band gap of the films was also calculated from the transmittance spectra.

Investigation of tin oxide nanofibers synthesized via bio-template technique

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kundu, Virender Singh, E-mail: vskundu-kuk@rediffmail.com; Dhiman, Jonny; Kumar, Suresh

In the present paper tin oxide nanofibers have been by synthesized using cotton as bio-template via sol-gel route. This is comparatively a new synthesis technique. The structure and morphology of the obtained SnO{sub 2} nanofibers were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDX). The optical properties of the same have been studied by using UV-Vis spectroscopy. The observed XRD pattern showed that peaks are very narrow and sharp which indicates crystalline nature of samples. SEM images gave an idea about the sample morphology and confirm that the obtained sample were nanofibers. The optical absorbancemore » spectrum of the sample under study was recorded in UV-visible region (200nm- 800nm). The band gap of the sample was found to be 3.95 eV which is higher than their bulk counterpart.« less

Optical, morphological and structural characterization of Langmuir-Schaefer films of a functionalized copper phthalocyanine.

PubMed

Giancane, Gabriele; Filippo, Emanuela; Manno, Daniela; Serra, Antonio; Valli, Ludovico

2011-11-01

Langmuir-Schaefer (LS) films of copper(II) tetrakis-(isoprpoxy-carbonyl)-phthalocyanine (TiPCuPc) have been deposited onto various solid supports. Its floating film have been characterized at the air-water interface by means of Brewster Angle Microscopy and Langmuir curves. Vibrational modes of multilayer transferred LS film have been studied by Raman spectroscopy and the optical parameters (refractive index n and extinction coefficient k) have been determined in the visible range of the electromagnetic spectrum. Linearly polarized light absorbance measurements have been performed at room temperature in the 400-800 nm spectral range and the average orientation of the phthalocyanine rings have been estimated. Transmission electron microscopy has been also used to characterize the morphological properties of the LS film and a close packed arrangement of the deposited molecules has been observed. Copyright © 2011 Elsevier Inc. All rights reserved.

Annealing induced reorientation of crystallites in Sn doped ZnO films

NASA Astrophysics Data System (ADS)

Ravichandran, K.; Vasanthi, M.; Thirumurugan, K.; Sakthivel, B.; Karthika, K.

2014-11-01

Tin doped ZnO thin films were prepared by employing a simplified spray pyrolysis technique using a perfume atomizer and subsequently annealed under different temperatures from 350 °C to 500 °C in steps of 50 °C. The structural, optical, electrical, photoluminescence and surface morphological properties of the as-deposited films were studied and compared with that of the annealed films. The X-ray diffraction studies showed that as-deposited film exhibits preferential orientation along the (0 0 2) plane and it changes in favour of (1 0 0) plane after annealing. The increase in crystallite size due to annealing is explained on the basis of Ostwald ripening effect. It is found that the optical transmittance and band gap increases with increase in annealing temperature. A slight decrease in resistivity caused by annealing is discussed in correlation with annealing induced defect modifications and surface morphology.

Influence of Y doping concentration on the properties of nanostructured MxZn1-xO (M=Y) thin film deposited by nebulizer spray pyrolysis technique

NASA Astrophysics Data System (ADS)

Mariappan, R.; Ponnuswamy, V.; Chandra Bose, A.; Suresh, R.; Ragavendar, M.

2014-09-01

Yttrium doped Zinc Oxide (YxZn1-xO) thin films deposited at a substrate temperature 400 °C. The effect of substrate temperature on the structural, surface morphology, compositional, optical and electrical properties of YxZn1-xO thin films was studied. X-ray diffraction studies show that all films are polycrystalline in nature with hexagonal crystal structure having highly textured (002) plane parallel to the surface of the substrate. The structural parameters, such as lattice constants (a and c), crystallite size (D), dislocation density (δ), microstrain (σ) and texture coefficient were calculated for different yttrium doping concentrations (x). High resolution scanning electron microscopy measurements reveal that the surface morphology of the films change from platelet like grains to hexagonal structure with grain size increase due to the yttrium doping. Energy dispersive spectroscopy confirms the presence of Y, Zn and O elements in the films prepared. Optical studies showed that all samples have a strong optical transmittance higher than 70% in the visible range. A slight shift of the absorption edge towards the large wavelengths was observed as the Y doping concentration increased. This result shows that the band gap is slightly decreased from 3.10 to 2.05 eV with increase of the yttrium doping concentrations (up to 7.5%) and then slightly increased. Room temperature PL measurements were done and the band-to-band emission energies of films were determined and reported. The complex impedance of the 10%Y doped ZnO film shows two distinguished semicircles and the diameter of the arcs got decreased in diameter as the temperature increases from 70 to 175 °C.

Laser ablation of Au-CuO core-shell nanocomposite in water for optoelectronic devices

NASA Astrophysics Data System (ADS)

Ismail, Raid A.; Abdul-Hamed, Ryam S.

2017-12-01

Core-shell gold-copper oxide Au-CuO nanocomposites were synthesized using laser ablation of CuO target in colloidal solution of Au nanoparticles (NPs). The effect of laser fluence on the structural, morphological, electrical, and optical properties of Au-CuO nanocomposites was investigated using x-ray diffraction (XRD), atomic force microscope (AFM), scanning electron microscope (SEM), transmission electron microscope (TEM), photoluminescence (PL), Fourier transformed infrared spectroscopy (FTIR), Hall measurement, and UV-vis spectroscopy. X-ray diffraction results confirm the formation of polycrystalline Au-CuO NPs with monoclinic structure. The optical energy gap for CuO was 4 eV and for the Au-CuO core-shell nanocomposites was found to be in the range of 3.4-3.7 eV. SEM and TEM investigations revealed that the structure and morphology of Au-CuO core-shell nanocomposites were strongly depending on the laser fluence. A formation of Au-CuO nanospheres and platelets structures was observed. The photoluminescence data showed an emission of broad visible peaks between 407 and 420 nm. The effect of laser fluence on the dark and illuminated I-V characteristics of Au-CuO/n-Si heterojunction photodetectors was investigated and analyzed. The experimental data demonstrated that the photodetector prepared at optimum laser fluence exhibited photosensitivity of 0.6 AW-1 at 800 nm.

Influence of Lanthanum Doping on the Structural and Optical Properties of Hematite Nanopowders

NASA Astrophysics Data System (ADS)

Justus, J. Sharmila; Dharma Roy, S. Dawn; Raj, A. Moses Ezhil

2016-10-01

Rare-earth elements are an attractive class of dopant elements, as they give easily trivalent cations that possibly altering the structure and other properties of the parent nanoparticles and creating multifunctional materials because of their f-electronic configurations. Herein, experimental evidence has been given for a better understanding of the factors that dictate the interactions of La doping on the structure and optical properties of iron oxide nanoparticles. For that, lanthanum doped hematite (α-Fe2O3) nanoparticles were prepared by a facile solution method using iron (III) chloride (FeCl3) as starting precursor and sodium hydroxide (NaOH) as reducing agent without templates at low temperature. As-prepared powders were subsequently calcined in air for 3 hr at 800 °C. Xray diffraction (XRD) technique was used to study the nanocrystal formation of α-Fe2O3 and Fourier Transform Raman (FT-Raman) spectral information identified the chemical bond structure of the nanoparticles. Morphology study of the nanoparticles was identified using Scanning Electron Microscope (SEM) and the incorporated La content was recognized from the Energy Dispersive X-ray Spectroscopy (EDS) analysis. The optical absorption spectrum was recorded in the wavelength range of 200-2000 nm and the optical parameters such as absorption coefficient and optical band gap energy of pure and doped Fe2O3 nanoparticles were determined. Obtained results are interpreted by considering the impregnation of trivalent La cations that replaced Fe cations of the host structure.

Cholesterol biosensor based on a plastic optical fibre with sol-gel: structural analysis and sensing properties

NASA Astrophysics Data System (ADS)

Razo-Medina, D. A.; Trejo-Durán, M.; Alvarado-Méndez, E.

2018-02-01

In this paper, we report the design and characterization of an optical fibre cholesterol biosensor by using sol-gel immobilization technique. The cholesterol enzyme is encapsulated inside of the sol-gel film onto an end of a plastic optical fibre. Two film deposition methods (Dip-Coating and Immersion) were studied. The morphology analysis and sensing properties permit us to determine the best film deposition to sense cholesterol concentration. The range of measured is 4.4-5.2 mM in real time and our results were validated by comparing them with other previously published results. The biosensor is portable, simple cheap, and easy to use.

Pronounced effects of the nominal concentrations of WO3 and Ag: WO3 nano-plates (obtained by a co-precipitation method) on their structural, morphological and optical properties

NASA Astrophysics Data System (ADS)

Rajendran, V.; Deepa, B.

2018-03-01

Tungsten oxide and different concentration of silver (Ag)-doped tungsten oxide nano material were synthesized by co-precipitation technique. The functional vibrations, structure, and morphology of as-prepared nano material were studied by Fourier transmission infrared spectroscopy, X-ray diffraction, scanning electron microscopy (SEM) and High-resolution transmission electron microscopy (HR-TEM) techniques. The SEM and HR-TEM analysis revealed the formation of nano-plate/nano rods with an average diameter of 40-80 nm diameter and 1-1.5 mm length. Fluorescence (PL) and UV-visible absorption techniques have been used to study the optical properties of the prepared nanoparticles. The observed red shift in the visible absorption spectra confirmed the promoted electron-phonon interaction in WO3 and Ag: WO3 nanoparticles compared to bulk structures. The photoluminescence of nanocrystalline Ag2+ doped WO3 exhibited a strong violet-blue, blue-green emission. Concentration dependence of the emission intensity of Ag2+ in WO3 was studied, and the significant concentration was found to be 0.5% of Ag: WO3. The effluent dye degradation executed for the 0.5% of Ag: WO3 sample under the visible light which reveals the highest degradation efficiency in appropriate time.

Correlation of morphological and molecular parameters for colon cancer

NASA Astrophysics Data System (ADS)

Yuan, Shuai; Roney, Celeste A.; Li, Qian; Jiang, James; Cable, Alex; Summers, Ronald M.; Chen, Yu

2010-02-01

Colorectal cancer (CRC) is the second leading cause of cancer death in the United States. There is great interest in studying the relationship among microstructures and molecular processes of colorectal cancer during its progression at early stages. In this study, we use our multi-modality optical system that could obtain co-registered optical coherence tomography (OCT) and fluorescence molecular imaging (FMI) images simultaneously to study CRC. The overexpressed carbohydrate α-L-fucose on the surfaces of polyps facilitates the bond of adenomatous polyps with UEA-1 and is used as biomarker. Tissue scattering coefficient derived from OCT axial scan is used as quantitative value of structural information. Both structural images from OCT and molecular images show spatial heterogeneity of tumors. Correlations between those values are analyzed and demonstrate that scattering coefficients are positively correlated with FMI signals in conjugated. In UEA-1 conjugated samples (8 polyps and 8 control regions), the correlation coefficient is ranged from 0.45 to 0.99. These findings indicate that the microstructure of polyps is changed gradually during cancer progression and the change is well correlated with certain molecular process. Our study demonstrated that multi-parametric imaging is able to simultaneously detect morphology and molecular information and it can enable spatially and temporally correlated studies of structure-function relationships during tumor progression.

Correlated effects of preparation parameters and thickness on morphology and optical properties of ZnO very thin films

NASA Astrophysics Data System (ADS)

Gilliot, Mickaël; Hadjadj, Aomar

2015-08-01

Nano-granular ZnO layers have been grown using a sol-gel synthesis and spin-coating deposition process. Thin films with thicknesses ranging from 15 to 150 nm have been obtained by varying the number of deposition cycles and prepared with different synthesis conditions. Morphologies and optical properties have been carefully investigated by joint spectroscopic ellipsometry and atomic force microscopy. A correlation between the evolution of optical properties and grains morphology has been observed. It is shown that both synthesis temperature and concentration similarly allow us to change the correlated growth and properties evolution rate. Thickness variation associated to choice of synthesis parameters could be a useful way to tune morphology and optical properties of the nanostructured ZnO layers.

Impact of annealing on physical properties of e-beam evaporated polycrystalline CdO thin films for optoelectronic applications

NASA Astrophysics Data System (ADS)

Purohit, Anuradha; Chander, S.; Dhaka, M. S.

2017-04-01

An impact of annealing on the physical properties of polycrystalline CdO thin films is carried out in this study. CdO thin films of thickness 650 nm were fabricated on glass and indium tin oxide (ITO) substrates employing e-beam evaporation technique. The pristine thin films were annealed in air atmosphere at 250 °C, 400 °C and 550 °C for one hour followed by investigation of structural, optical, electrical and morphological properties along with elemental composition using X-ray diffraction (XRD), UV-Vis spectrophotometer, Fourier transform infrared (FTIR) spectrometer, source meter, scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS), respectively. XRD patterns confirmed the polycrystalline nature and cubic structure (with space group Fm 3 bar m) of the films. The crystallographic parameters are calculated and found to be influenced by the post-air annealing treatment. The optical study shows that direct band gap is ranging from 1.98 eV to 2.18 eV and found to be decreased with post-annealing. The refractive index and optical conductivity are also increased with annealing temperature. The current-voltage characteristics show ohmic behaviour of the annealed films. The surface morphology is observed to be improved with annealing and grain-size is increased as well as EDS spectrum confirmed the presence of cadmium (Cd) and oxygen (O) in the deposited films.

Effect of silver ion-induced disorder on morphological, chemical and optical properties of poly (methyl methacrylate)

NASA Astrophysics Data System (ADS)

Arif, Shafaq; Saleemi, Farhat; Rafique, M. Shahid; Naab, Fabian; Toader, Ovidiu; Mahmood, Arshad; Aziz, Uzma

2016-11-01

Ion implantation is a versatile technique to tailor the surface properties of polymers in a controlled manner. In the present study, samples of poly (methyl methacrylate) (PMMA) have been implanted with 400 keV silver (Ag+) ion beam to various ion fluences ranging from 5 × 1013 to 5 × 1015 ions/cm2. The effect of Ag+ ion-induced disorder on morphological, chemical and optical properties of PMMA is analyzed using Atomic Force Microscope (AFM), Fourier transform infrared spectroscopy (FTIR) and ultraviolet-visible (UV-Vis) spectroscopy. Furthermore, the electrical conductivity of pristine and implanted PMMA is measured using four probe apparatus. The AFM images revealed the growth of nano-sized grainy structures and hillocks above the surface of implanted PMMA. The FTIR spectra confirmed the modifications in chemical structure of PMMA along with the formation of sbnd Cdbnd Csbnd carbon contents. The refractive index, extinction coefficient and photoconductivity of implanted PMMA have been found to increase as a function of ion fluence. Simultaneously, indirect optical band gap is reduced from 3.13 to 0.81 eV at a relatively high fluence (5 × 1015 ions/cm2). A linear correlation has been established between the band gap and Urbach energies. Moreover, the electrical conductivity of Ag+ implanted PMMA has increased from 2.14 × 10-10 (pristine) to 9.6 × 10-6 S/cm.

Effect of thickness on surface morphology, optical and humidity sensing properties of RF magnetron sputtered CCTO thin films

NASA Astrophysics Data System (ADS)

Ahmadipour, Mohsen; Ain, Mohd Fadzil; Ahmad, Zainal Arifin

2016-11-01

In this study, calcium copper titanate (CCTO) thin films were deposited on ITO substrates successfully by radio frequency (RF) magnetron sputtering method in argon atmosphere. The CCTO thin films present a polycrystalline, uniform and porous structure. The surface morphology, optical and humidity sensing properties of the synthesized CCTO thin films have been studied by X-ray diffraction (XRD), atomic force microscopy (AFM), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDX), UV-vis spectrophotometer and current-voltage (I-V) analysis. XRD and AFM confirmed that the intensity of peaks and pore size of CCTO thin films were enhanced by increasing the thin films. Tauc plot method was adopted to estimate the optical band gaps. The surface structure and energy band gaps of the deposited films were affected by film thickness. Energy band gap of the layers were 3.76 eV, 3.68 eV and 3.5 eV for 200 nm, 400 nm, and 600 nm CCTO thin films layer, respectively. The humidity sensing properties were measured by using direct current (DC) analysis method. The response times were 12 s, 22 s, and 35 s while the recovery times were 500 s, 600 s, and 650 s for 200 nm, 400 nm, and 600 nm CCTO thin films, respectively at humidity range of 30-90% relative humidity (RH).

Structural and optical properties of Ag-doped copper oxide thin films on polyethylene napthalate substrate prepared by low temperature microwave annealing

NASA Astrophysics Data System (ADS)

Das, Sayantan; Alford, T. L.

2013-06-01

Silver doped cupric oxide thin films are prepared on polyethylene naphthalate (flexible polymer) substrates. Thin films Ag-doped CuO are deposited on the substrate by co-sputtering followed by microwave assisted oxidation of the metal films. The low temperature tolerance of the polymer substrates led to the search for innovative low temperature processing techniques. Cupric oxide is a p-type semiconductor with an indirect band gap and is used as selective absorption layer solar cells. X-ray diffraction identifies the CuO phases. Rutherford backscattering spectrometry measurements confirm the stoichiometry of each copper oxide formed. The surface morphology is determined by atomic force microscopy. The microstructural properties such as crystallite size and the microstrain for (-111) and (111) planes are calculated and discussed. Incorporation of Ag led to the lowering of band gap in CuO. Consequently, it is determined that Ag addition has a strong effect on the structural, morphological, surface, and optical properties of CuO grown on flexible substrates by microwave annealing. Tauc's plot is used to determine the optical band gap of CuO and Ag doped CuO films. The values of the indirect and direct band gap for CuO are found to be 2.02 eV and 3.19 eV, respectively.

Using Polarized Spectroscopy to Investigate Order in Thin-Films of Ionic Self-Assembled Materials Based on Azo-Dyes

PubMed Central

Ahmad, Mariam; Andersen, Frederik; Brend Bech, Ári; Bendixen, H. Krestian L.; Nawrocki, Patrick R.; Bloch, Anders J.; Bora, Ilkay; Bukhari, Tahreem A.; Bærentsen, Nicolai V.; Carstensen, Jens; Chima, Smeeah; Colberg, Helene; Dahm, Rasmus T.; Daniels, Joshua A.; Dinckan, Nermin; El Idrissi, Mohamed; Erlandsen, Ricci; Førster, Marc; Ghauri, Yasmin; Gold, Mikkel; Hansen, Andreas; Hansen, Kenn; Helmsøe-Zinck, Mathias; Henriksen, Mathias; Hoffmann, Sophus V.; Hyllested, Louise O. H.; Jensen, Casper; Kallenbach, Amalie S.; Kaur, Kirandip; Khan, Suheb R.; Kjær, Emil T. S.; Kristiansen, Bjørn; Langvad, Sylvester; Lund, Philip M.; Munk, Chastine F.; Møller, Theis; Nehme, Ola M. Z.; Nejrup, Mathilde Rove; Nexø, Louise; Nielsen, Simon Skødt Holm; Niemeier, Nicolai; Nikolajsen, Lasse V.; Nøhr, Peter C. T.; Skaarup Ovesen, Jacob; Paustian, Lucas; Pedersen, Adam S.; Petersen, Mathias K.; Poulsen, Camilla M.; Praeger-Jahnsen, Louis; Qureshi, L. Sonia; Schiermacher, Louise S.; Simris, Martin B.; Smith, Gorm; Smith, Heidi N.; Sonne, Alexander K.; Zenulovic, Marko R.; Winther Sørensen, Alma; Vogt, Emil; Væring, Andreas; Westermann, Jonas; Özcan, Sevin B.

2018-01-01

Three series of ionic self-assembled materials based on anionic azo-dyes and cationic benzalkonium surfactants were synthesized and thin films were prepared by spin-casting. These thin films appear isotropic when investigated with polarized optical microscopy, although they are highly anisotropic. Here, three series of homologous materials were studied to rationalize this observation. Investigating thin films of ordered molecular materials relies to a large extent on advanced experimental methods and large research infrastructure. A statement that in particular is true for thin films with nanoscopic order, where X-ray reflectometry, X-ray and neutron scattering, electron microscopy and atom force microscopy (AFM) has to be used to elucidate film morphology and the underlying molecular structure. Here, the thin films were investigated using AFM, optical microscopy and polarized absorption spectroscopy. It was shown that by using numerical method for treating the polarized absorption spectroscopy data, the molecular structure can be elucidated. Further, it was shown that polarized optical spectroscopy is a general tool that allows determination of the molecular order in thin films. Finally, it was found that full control of thermal history and rigorous control of the ionic self-assembly conditions are required to reproducibly make these materials of high nanoscopic order. Similarly, the conditions for spin-casting are shown to be determining for the overall thin film morphology, while molecular order is maintained. PMID:29462883

Using Polarized Spectroscopy to Investigate Order in Thin-Films of Ionic Self-Assembled Materials Based on Azo-Dyes.

PubMed

Kühnel, Miguel R Carro-Temboury Martin; Ahmad, Mariam; Andersen, Frederik; Bech, Ári Brend; Bendixen, H Krestian L; Nawrocki, Patrick R; Bloch, Anders J; Bora, Ilkay; Bukhari, Tahreem A; Bærentsen, Nicolai V; Carstensen, Jens; Chima, Smeeah; Colberg, Helene; Dahm, Rasmus T; Daniels, Joshua A; Dinckan, Nermin; Idrissi, Mohamed El; Erlandsen, Ricci; Førster, Marc; Ghauri, Yasmin; Gold, Mikkel; Hansen, Andreas; Hansen, Kenn; Helmsøe-Zinck, Mathias; Henriksen, Mathias; Hoffmann, Sophus V; Hyllested, Louise O H; Jensen, Casper; Kallenbach, Amalie S; Kaur, Kirandip; Khan, Suheb R; Kjær, Emil T S; Kristiansen, Bjørn; Langvad, Sylvester; Lund, Philip M; Munk, Chastine F; Møller, Theis; Nehme, Ola M Z; Nejrup, Mathilde Rove; Nexø, Louise; Nielsen, Simon Skødt Holm; Niemeier, Nicolai; Nikolajsen, Lasse V; Nøhr, Peter C T; Orlowski, Dominik B; Overgaard, Marc; Ovesen, Jacob Skaarup; Paustian, Lucas; Pedersen, Adam S; Petersen, Mathias K; Poulsen, Camilla M; Praeger-Jahnsen, Louis; Qureshi, L Sonia; Ree, Nicolai; Schiermacher, Louise S; Simris, Martin B; Smith, Gorm; Smith, Heidi N; Sonne, Alexander K; Zenulovic, Marko R; Sørensen, Alma Winther; Sørensen, Karina; Vogt, Emil; Væring, Andreas; Westermann, Jonas; Özcan, Sevin B; Sørensen, Thomas Just

2018-02-15

Three series of ionic self-assembled materials based on anionic azo-dyes and cationic benzalkonium surfactants were synthesized and thin films were prepared by spin-casting. These thin films appear isotropic when investigated with polarized optical microscopy, although they are highly anisotropic. Here, three series of homologous materials were studied to rationalize this observation. Investigating thin films of ordered molecular materials relies to a large extent on advanced experimental methods and large research infrastructure. A statement that in particular is true for thin films with nanoscopic order, where X-ray reflectometry, X-ray and neutron scattering, electron microscopy and atom force microscopy (AFM) has to be used to elucidate film morphology and the underlying molecular structure. Here, the thin films were investigated using AFM, optical microscopy and polarized absorption spectroscopy. It was shown that by using numerical method for treating the polarized absorption spectroscopy data, the molecular structure can be elucidated. Further, it was shown that polarized optical spectroscopy is a general tool that allows determination of the molecular order in thin films. Finally, it was found that full control of thermal history and rigorous control of the ionic self-assembly conditions are required to reproducibly make these materials of high nanoscopic order. Similarly, the conditions for spin-casting are shown to be determining for the overall thin film morphology, while molecular order is maintained.

Microstructure and ferroelectricity of BaTiO3 thin films on Si for integrated photonics

NASA Astrophysics Data System (ADS)

Kormondy, Kristy J.; Popoff, Youri; Sousa, Marilyne; Eltes, Felix; Caimi, Daniele; Rossell, Marta D.; Fiebig, Manfred; Hoffmann, Patrik; Marchiori, Chiara; Reinke, Michael; Trassin, Morgan; Demkov, Alexander A.; Fompeyrine, Jean; Abe, Stefan

2017-02-01

Significant progress has been made in integrating novel materials into silicon photonic structures in order to extend the functionality of photonic circuits. One of these promising optical materials is BaTiO3 or barium titanate (BTO) that exhibits a very large Pockels coefficient as required for high-speed light modulators. However, all previous demonstrations show a noticable reduction of the Pockels effect in BTO thin films deposited on silicon substrates compared to BTO bulk crystals. Here, we report on the strong dependence of the Pockels effect in BTO thin films on their microstructure, and provide guidelines on how to engineer thin films with strong electro-optic response. We employ several deposition methods such as molecular beam epitaxy and chemical vapor deposition to realize BTO thin films with different morphology and crystalline structure. While a linear electro-optic response is present even in porous, polycrystalline BTO thin films with an effective Pockels coefficient r eff = 6 pm V-1, it is maximized for dense, tetragonal, epitaxial BTO films (r eff = 140 pm V-1). By identifying the key structural predictors of electro-optic response in BTO/Si, we provide a roadmap to fully exploit the linear electro-optic effect in novel hybrid oxide/semiconductor nanophotonic devices.

Structural and spectroscopic analysis of ex-situ annealed RF sputtered aluminium doped zinc oxide thin films

NASA Astrophysics Data System (ADS)

Otieno, Francis; Airo, Mildred; Erasmus, Rudolph M.; Billing, David G.; Quandt, Alexander; Wamwangi, Daniel

2017-08-01

Aluminium doped zinc oxide thin films are prepared by Radio Frequency magnetron sputtering in pure argon atmosphere at 100 W. The structural results reveal good film adhesion on a silicon substrate (001). The thin films were then subjected to heat treatment in a furnace under ambient air. The structural, morphological, and optical properties of the thin films as a function of deposition time and annealing temperatures have been investigated using Grazing incidence X-Ray Diffraction (GIXRD), Atomic Force Microscopy, and Scanning Electronic Microscopy. The photoluminescence properties of the annealed films showed significant changes in the optical properties attributed to mid gap defects. Annealing increases the crystallite size and the roughness of the film. The crystallinity of the films also improved as evident from the Raman and XRD studies.

Direct Interferometric Imaging with IOTA Interferometer: Morphology of the Water Shell around U Ori

NASA Astrophysics Data System (ADS)

Pluzhnik, Eugene; Ragland, S.; Le Coroller, H.; Cotton, W.; Danchi, W.; Traub, W.; Willson, L.

2007-12-01

Optical interferometric observations of Mira stars with adequate resolution using the 3-telescope Infrared Optical Telescope Array (IOTA) interferometer have shown detectable asymmetry in several Mira stars. Several mechanisms have been proposed to explain the observed asymmetry. In this paper, we present subsequent IOTA observations of a Mira star, namely, U Ori taken at 1.51, 1.64 and 1.78 μm in 2005. The reconstructed images based on a model independent algorithm are also presented. These images show asymmetric structures of the water shell that is similar to the structure of 22 GHz masers obtained by Vlemmings et al. in 2003. We explore the possibility of the detection of molecular shell rotation with a period of about 30 years by comparing our results with radio observations and discuss a possible geometric structure of the shell.

Influences of annealing temperature on sprayed CuFeO2 thin films

NASA Astrophysics Data System (ADS)

Abdelwahab, H. M.; Ratep, A.; Abo Elsoud, A. M.; Boshta, M.; Osman, M. B. S.

2018-06-01

Delafossite CuFeO2 thin films were successfully prepared onto quartz substrates using simple spray pyrolysis technique. Post annealing under nitrogen atmosphere for 2 h was necessary to form delafossite CuFeO2 phase. The effect of alteration in annealing temperature (TA) 800, 850 and 900 °C was study on structural, morphology and optical properties. The XRD results for thin film annealed at TA = 850 °C show single phase CuFeO2 with rhombohedral crystal system and R 3 bar m space group with preferred orientation along (0 1 2). The prepared copper iron oxide thin films have an optical transmission ranged ∼40% in the visible region. The optical direct optical band gap of the prepared thin films was ranged ∼2.9 eV.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Marimuthu, T.; Anandhan, N., E-mail: anandhan-kn@rediffmail.com; Mummoorthi, M.

Zinc oxide (ZnO) and zinc oxide/eosin yellow (ZnO/EY) thin films were potentiostatically deposited onto fluorine doped tin oxide (FTO) glass substrate. Effect of eosin yellow dye on structural, morphological and optical properties was studied. X-ray diffraction patterns, micro Raman spectra and photoluminescence (PL) spectra reveal hexagonal wurtzite structure with less atomic defects in 101 plane orientation of the ZnO/EY film. Scanning electron microscopy (SEM) images show flower for ZnO and porous like structure for ZnO/EY thin film, respectively. DSSC was constructed and evaluated by measuring the current density verses voltage curve.

Self-assembly of chlorophenols in water

PubMed Central

Rogalska, Ewa; Rogalski, Marek; Gulik-Krzywicki, Tadeusz; Gulik, Annette; Chipot, Christophe

1999-01-01

In saturated solutions of some di- and trichlorophenols, structures with complex morphologies, consisting of thin, transparent sheets often coiling into helices and ultimately twisting into filaments, were observed under the optical microscope. Freeze-fracture electron microscopy, x-ray diffraction, phase diagrams, and molecular modeling were performed to elucidate the observed phenomena. Here, we present evidence that the chlorophenols studied, when interacting with water, self-assemble into bilayers. The fact that some chlorophenols form the same supramolecular structures as those described previously for structurally nonrelated surfactants sheds light on the mechanisms of self-assembly. PMID:10359753

Optical and structural properties of carbon dots/TiO2 nanostructures prepared via DC arc discharge in liquid

NASA Astrophysics Data System (ADS)

Biazar, Nooshin; Poursalehi, Reza; Delavari, Hamid

2018-01-01

Synthesis and development of visible active catalysts is an important issue in photocatalytic applications of nanomaterials. TiO2 nanostructures coupled with carbon dots demonstrate a considerable photocatalytic activity in visible wavelengths. Extending optical absorption of a wide band gap semiconductor such as TiO2 with carbon dots is the origin of the visible activity of carbon dots modified semiconductor nanostructures. In addition, carbon dots exhibit high photostability, appropriate electron transport and chemical stability without considerable toxicity or environmental footprints. In this study, optical and structural properties of carbon dots/TiO2 nanostructures prepared via (direct current) DC arc discharge in liquid were investigated. Crystal structure, morphology and optical properties of the samples were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), and UV-visible spectroscopy respectively. SEM images show formation of spherical nanoparticles with an average size of 27 nm. In comparison with pristine TiO2, optical transmission spectrum of carbon dots/TiO2 nanostructures demonstrates an absorption edge at longer wavelengths as well a high optical absorption in visible wavelengths which is significant for visible activity of nanostructures as a photocatalyst. Finally, these results can provide a flexible and versatile pathway for synthesis of carbon dots/oxide semiconductor nanostructures with an appropriate activity under visible light.

Structural and optical studies of porous silicon buried waveguides: Effects of oxidation and pore filling using DR1 dyes

NASA Astrophysics Data System (ADS)

Charrier, J.; Kloul, M.; Pirasteh, P.; Bardeau, J.-F.; Guendouz, M.; Bulou, A.; Haji, L.

2007-11-01

This paper deals with the structural and optical properties of buried waveguides manufactured from mesoporous silicon films (as-formed porous silicon layers, after oxidation, after filling with active DR1 dyes). It is shown that the oxidation process only induced a weak morphology transformation. The 2D profiles of cross-sections of the waveguides by micro-Raman mapping were done in order to check the oxidation rate and to probe the DR1 filling of the layers. This latter appeared homogeneous but surprisingly is greater in the weaker porosity layer. The light propagation through these different waveguides was observed and losses were measured and analyzed. The losses decreased after oxidation but they increased after filling.

Rapid synthesis of flower shaped Cu{sub 2}ZnSnS{sub 4} nanoparticles by microwave irradiation for solar cell application

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ansari, Mohd Zubair, E-mail: mhd.zubair1@gmail.com; Khare, Neeraj

Single phase Cu{sub 2}ZnSnS{sub 4} (CZTS) nanoparticles have been synthesized by the microwave-assisted solution method in a one step process. Structural, morphological and optical characterizations of the CZTS nanoparticles have been carried out. X-ray diffraction confirms the single phase formation of CZTS nanoparticles with kesterite structure. SEM confirms the homogenous distribution of CZTS nanoparticles flower like assemblies. High resolution TEM image confirms the good crystallinity of the CZTS nanoparticles with the average grain size ~20 nm. The CZTS nanoparticles have strong optical absorption in the visible region with direct band gap as ~1.6 eV which is optimal for photovoltaic application.

Influence of vacuum annealing on the properties of Cu2SnS3 thin films using low cost ultrasonic spray pyrolysis

NASA Astrophysics Data System (ADS)

Rahaman, Sabina; Sunil, M. Anantha; Shaik, Habibuddin; Ghosh, Kaustab

2018-05-01

Deposition of Cu2SnS3 (CTS) thin films is successfully carried out on soda lime glass substrate using low cost ultrasonic spray pyrolysis technique. Vacuum annealing of CTS films is carried out at different temperatures 350°C, 400°C and 450°C. The present work is to study the effect of annealing temperature on the crystal structure, surface morphology and optical properties of CTS thin films. Structural studies confirm the formation of CTS phase. Raman analysis is carried out to study presence of defects with annealing temperature. Optical studies confirm that film prepared at 450°C temperature is suitable as absorber material for photovoltaic applications.

Variation of the radiative properties during black carbon aging: theoretical and experimental intercomparison

DOE PAGES

He, C.; Liou, K.-N.; Takano, Y.; ...

2015-07-20

A theoretical black carbon (BC) aging model is developed to account for three typical evolution stages, namely, freshly emitted aggregates, coated BC by soluble material, and BC particles undergoing further hygroscopic growth. The geometric-optics surface-wave (GOS) approach is employed to compute the BC single-scattering properties at each aging stage, which are subsequently compared with laboratory measurements. Theoretical calculations are consistent with measurements in extinction and absorption cross sections for fresh BC aggregates, but overestimate the scattering cross sections for BC mobility diameters of 155, 245, and 320 nm, because of uncertainties associated with theoretical calculations for small particles as wellmore » as laboratory scattering measurements. The measured optical cross sections for coated BC by sulfuric acid and for those undergoing further hygroscopic growth are captured by theoretical calculations using a concentric core-shell structure, with differences of less than 20 %. This suggests that the core-shell shape represents the realistic BC coating morphology reasonably well in this case, which is consistent with the observed strong structure compaction during aging. We find that the absorption and scattering properties of fresh BC aggregates vary by up to 60 % due to uncertainty in the BC refractive index, which, however, is a factor of two smaller in the case of coated BC particles. Sensitivity analyses on the BC morphology show that the optical properties of fresh BC aggregates are more sensitive to fractal dimension than primary spherule size. The absorption and scattering cross sections of coated BC particles vary by more than a factor of two due to different coating structures. We find an increase of 20–250 % in absorption and a factor of 3–15 in scattering during aging, significantly depending on coating morphology and aging stages. Applying the aging model to CalNex 2010 field measurements, we show that the resulting BC direct radiative forcing (DRF) first increases from 1.5 to 1.7 W m -2 and subsequently decreases to 1.0 W m -2 during the transport from the Los Angeles Basin to downwind regions, as a result of the competition between absorption enhancement due to coating and dilution of BC concentration. The BC DRF can vary by up to a factor of two due to differences in BC coating morphology. Thus, an accurate estimate of BC DRF requires the incorporation of a dynamic BC aging process that accounts for realistic morphology in climate models, particularly for the regional analysis with high atmospheric heterogeneity.« less

Variation of the radiative properties during black carbon aging: theoretical and experimental intercomparison

DOE Office of Scientific and Technical Information (OSTI.GOV)

He, C.; Liou, K.-N.; Takano, Y.

A theoretical black carbon (BC) aging model is developed to account for three typical evolution stages, namely, freshly emitted aggregates, coated BC by soluble material, and BC particles undergoing further hygroscopic growth. The geometric-optics surface-wave (GOS) approach is employed to compute the BC single-scattering properties at each aging stage, which are subsequently compared with laboratory measurements. Theoretical calculations are consistent with measurements in extinction and absorption cross sections for fresh BC aggregates, but overestimate the scattering cross sections for BC mobility diameters of 155, 245, and 320 nm, because of uncertainties associated with theoretical calculations for small particles as wellmore » as laboratory scattering measurements. The measured optical cross sections for coated BC by sulfuric acid and for those undergoing further hygroscopic growth are captured by theoretical calculations using a concentric core-shell structure, with differences of less than 20 %. This suggests that the core-shell shape represents the realistic BC coating morphology reasonably well in this case, which is consistent with the observed strong structure compaction during aging. We find that the absorption and scattering properties of fresh BC aggregates vary by up to 60 % due to uncertainty in the BC refractive index, which, however, is a factor of two smaller in the case of coated BC particles. Sensitivity analyses on the BC morphology show that the optical properties of fresh BC aggregates are more sensitive to fractal dimension than primary spherule size. The absorption and scattering cross sections of coated BC particles vary by more than a factor of two due to different coating structures. We find an increase of 20–250 % in absorption and a factor of 3–15 in scattering during aging, significantly depending on coating morphology and aging stages. Applying the aging model to CalNex 2010 field measurements, we show that the resulting BC direct radiative forcing (DRF) first increases from 1.5 to 1.7 W m -2 and subsequently decreases to 1.0 W m -2 during the transport from the Los Angeles Basin to downwind regions, as a result of the competition between absorption enhancement due to coating and dilution of BC concentration. The BC DRF can vary by up to a factor of two due to differences in BC coating morphology. Thus, an accurate estimate of BC DRF requires the incorporation of a dynamic BC aging process that accounts for realistic morphology in climate models, particularly for the regional analysis with high atmospheric heterogeneity.« less

Aging effects of the precursor solutions on the properties of spin coated Ga-doped ZnO thin films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Serrao, Felcy Jyothi, E-mail: jyothiserrao@gmail.com; Dharmaprakash, S. M.

2015-06-24

In this study, gallium doped zinc oxide thin films (GZO) were grown on a glass substrate by a simple sol-gel process and spin coating technique using zinc acetate and gallium nitrate (3at%) as precursors for Zn and Ga ions respectively. The effects of aging time of the precursor solution on the structural and optical properties of the GZO films were investigated. The surface morphology, grain size, film thickness and optical properties of the GZO films were found to depend directly on the sol aging time. XRD studies reveal that the films are polycrystalline with a hexagonal wurtzite structure and showmore » the c-axis grain orientation. Optical transmittance spectra of all the films exhibited transmittance higher than about 82% within the visible wavelength region. A sharp fundamental absorption edge with a slight blue shifting was observed with an increase in sol aging time which can be explained by Burstein-Moss effect. The result indicates that an appropriate aging time of the sol is important for the improvement of the structural and optical properties of GZO thin films derived from sol-gel method.« less

Synthesis, structural and optical properties of ZnO spindle/reduced graphene oxide composites with enhanced photocatalytic activity under visible light irradiation

NASA Astrophysics Data System (ADS)

Prabhu, S.; Pudukudy, M.; Sohila, S.; Harish, S.; Navaneethan, M.; Navaneethan, D.; Ramesh, R.; Hayakawa, Y.

2018-05-01

In the present work, spindle-shaped ZnO and reduced graphene oxide sheets were successfully synthesized by a hydrothermal method and then ZnO/r-GO composite was prepared by a direct solution mixing method. Various characterization results confirmed the interior and surface decoration of spindle-shaped ZnO on the reduced graphene oxide sheets. The phase formation, crystalline structure, morphology, surface states and optical properties were characterized using Powder X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), Transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Fourier Transform Infrared Spectroscopy (FTIR) and UV-Vis spectroscopy. The X-ray diffraction analysis showed the formation of the hexagonal wurtzite crystalline structure of ZnO with high crystalline quality. The band gap of the ZnO/r-GO composite was found to be low (3.03eV) compared to the band gap of spindle shaped ZnO (3.13 eV), as calculated from optical studies. The spindle-like morphology of the single crystalline ZnO was clearly shown in the electron microscopic images. The chemical bonding and surface states of the samples were studied using XPS measurement. Moreover, a possible growth mechanism for the ZnO spindle was proposed. The catalytic activity of the as-synthesized samples was evaluated for the photodegradation of methylene blue under visible light irradiation. Among the synthesized samples, the ZnO/r-GO composite showed higher degradation efficiency of 93% and successfully reused for four consecutive run without any activity loss.

Novel artificial optical annular structures in the high latitude ionosphere over EISCAT

NASA Astrophysics Data System (ADS)

Kosch, M. J.; Rietveld, M. T.; Senior, A.; McCrea, I. W.; Kavanagh, A. J.; Isham, B.; Honary, F.

2004-06-01

The EISCAT low-gain HF facility has been used repeatedly to produce artificially stimulated optical emissions in the F-layer ionosphere over northern Scandinavia. On 12 November 2001, the high-gain HF facility was used for the first time. The pump beam zenith angle was moved in 3° steps along the north-south meridian from 3°N to 15°S, with one pump cycle per position. Only when pumping in the 9°S position were annular optical structures produced quite unexpectedly. The annuli were approximately centred on the pump beam but outside the -3 dB locus. The optical signature appears to form a cylinder, which was magnetic field-aligned, rising above the pump wave reflection altitude. The annulus always collapsed into the well-known optical blobs after ~60 s, whilst descending many km in altitude. All other pump beam directions produced optical blobs only. The EISCAT UHF radar, which was scanning from 3° to 15°S zenith angle, shows that enhanced ion-line backscatter persisted throughout the pump on period and followed the morphology of the optical signature. These observations provide the first experimental evidence that Langmuir turbulence can accelerate electrons sufficiently to produce the optical emissions at high latitudes. Why the optical annulus forms, and for only one zenith angle, remains unexplained.

Deposition and characterization of ZnSe nanocrystalline thin films

NASA Astrophysics Data System (ADS)

Temel, Sinan; Gökmen, F. Özge; Yaman, Elif; Nebi, Murat

2018-02-01

ZnSe nanocrystalline thin films were deposited at different deposition times by using the Chemical Bath Deposition (CBD) technique. Effects of deposition time on structural, morphological and optical properties of the obtained thin films were characterized. X-ray diffraction (XRD) analysis was used to study the structural properties of ZnSe nanocrystalline thin films. It was found that ZnSe thin films have a cubic structure with a preferentially orientation of (111). The calculated average grain size value was about 28-30 nm. The surface morphology of these films was studied by the Field Emission Scanning Electron Microscope (FESEM). The surfaces of the thin films were occurred from small stacks and nano-sized particles. The band gap values of the ZnSe nanocrystalline thin films were determined by UV-Visible absorption spectrum and the band gap values were found to be between 2.65-2.86 eV.

Effect of Ce doping on structural, optical and photocatalytic properties of ZnO nano-structures.

PubMed

Selvam, N Clament Sagaya; Vijaya, J Judith; Kennedy, L John

2014-03-01

A novel self-assembled pure and Ce doped ZnO nano-particles (NPs) were successfully synthesized by a simple low temperature co-precipitation method. The prepared photocatalysts were characterized by X-ray diffraction (XRD), High resolution scanning electron microscopy (HR-SEM), High resolution transmission electron microscopy (HR-TEM), diffuse reflectance spectroscopy (DRS) and Photoluminescence (PL) spectroscopy. The results indicated that the prepared photocatalysts shows a novel morphology, high crystallinity, uniform size distribution, and more defects. Photocatalytic degradation (PCD) of nonylphenol, a potent endocrine disrupting chemical in aqueous medium was investigated. Higher amount of oxygen defects exhibits enhanced PCD of nonylphenol. In addition, the influence of the Ce contents on the structure, morphology, absorption, emission and photocatalytic activity of ZnO nanoparticles (NPs) were investigated systematically. The relative PCD efficiency of pure ZnO, Ce-doped ZnO NPs and commercial TiO2 (Degussa P-25) have also been discussed.

Synthesis of ZnO thin film by sol-gel spin coating technique for H2S gas sensing application

NASA Astrophysics Data System (ADS)

Nimbalkar, Amol R.; Patil, Maruti G.

2017-12-01

In this present work, zinc oxide (ZnO) thin film synthesized by a simple sol-gel spin coating technique. The structural, morphology, compositional, microstructural, optical, electrical and gas sensing properties of the film were studied by using XRD, FESEM, EDS, XPS, HRTEM, Raman, FTIR and UV-vis techniques. The ZnO thin film shows hexagonal wurtzite structure with a porous structured morphology. Gas sensing performance of synthesized ZnO thin film was tested initially for H2S gas at different operating temperatures as well as concentrations. The maximum gas response is achieved towards H2S gas at 300 °C operating temperature, at 100 ppm gas concentration as compared to other gases like CH3OH, Cl2, NH3, LPG, CH3COCH3, and C2H5OH with a good stability.

Zn doped CdO thin films with enhanced linear and third order nonlinear optical properties for optoelectronic applications

NASA Astrophysics Data System (ADS)

Bairy, Raghavendra; Jayarama, A.; Shivakumar, G. K.; Patil, P. S.; Bhat, K. Udaya

2018-04-01

Thin films of undoped and zinc doped CdO have been deposited on glass substrate using spray pyrolysis technique with various dopant concentrations of Zn such as 1, 5 and 10%. Influence of Zn doping on CdO thin films for the structural, morphological, optical and nonlinear optical properties are reported. XRD analysis reveals that as prepared pure and Zn doped CdO films show polycrystalline nature with face centered cubic structure. Also, Zn doping does not significantly modify the crystallinity and not much increase in the crystallite size of the film. SEM images shows grains which are uniform and grain size with increase in dopant concentration. The transmittance of the prepared CdO films recorded in the UV visible spectra and it shows 50 to 60% in the visible region. The estimated optical band gap increases from 2.60 to 2.70 eV for various dopant concentrations. The nonlinear optical absorption of Zn-doped CdO films have been measured used the Z-scan technique at a wavelength 532 nm. The nonlinear optical absorption coefficient (β), nonlinear refractive index (n2) and the third order nonlinear optical susceptibility (χ(3)) of the pure and Zn doped films were determined.

Impact of low-pressure glow-discharge-pulsed plasma polymerization on properties of polyaniline thin films

NASA Astrophysics Data System (ADS)

Jatratkar, Aviraj A.; Yadav, Jyotiprakash B.; Deshmukh, R. R.; Barshilia, Harish C.; Puri, Vijaya; Puri, R. K.

2016-12-01

This study reports on polyaniline thin films deposited on a glass substrate using a low-pressure glow-discharge-pulsed plasma polymerization method. The polyaniline thin film obtained by pulsed plasma polymerization has been successfully demonstrated as an optical waveguide with a transmission loss of 3.93 dB cm-1, and has the potential to be employed in integrated optics. An attempt has been made to investigate the effect of plasma OFF-time on the structural, optical as well as surface properties of polyaniline thin film. The plasma ON-time has been kept constant and the plasma OFF-time has been varied throughout the work. The plasma OFF-time strongly influenced the properties of the polyaniline thin film, and a nanostructured and compact surface was revealed in the morphological studies. The plasma OFF-time was found to enhance film thickness, roughness, refractive index and optical transmission loss, whereas it reduced the optical band gap of the polyaniline thin films. Retention in the aromatic structure was confirmed by FTIR results. Optical studies revealed a π-π* electronic transition at about 317 nm as well as the formation of a branched structure. As compared with continuous wave plasma, pulsed plasma polymerization shows better properties. Pulsed plasma polymerization reduced the roughness of the film from 1.2 nm to 0.42 nm and the optical transmission loss from 6.56 dB cm-1 to 3.39 dB cm-1.

Morphological and Compositional (S)TEM Analysis of Multiple Exciton Generation Solar Cells

NASA Astrophysics Data System (ADS)

Wisnivesky-Rocca-Rivarola, F.; Davis, N. J. L. K.; Bohm, M.; Ducati, C.

2015-10-01

Quantum confinement of charge carriers in semiconductor nanocrystals produces optical and electronic properties that have the potential to enhance the power conversion efficiency of solar cells. One of these properties is the efficient formation of more than one electron-hole pair from a single absorbed photon, in a process called multiple exciton generation (MEG). In this work we studied the morphology of nanocrystal multilayers of PbSe treated with CdCl2 using complementary imaging and spectroscopy techniques to characterise the chemical composition and morphology of full MEG devices made with PbSe nanorods (NRs). IN the scanning TEM (STEM), plan view images and chemical maps were obtained of the nanocrystal layers, which allowed for the analysis of crystal structure and orientation, as well as size distribution and aspect ratio. These results were complemented by cross-sectional images of full devices, which allowed accessing the structure of each layer that composes the device, including the nanorod packing in the active nanocrystal layer.

Experimental and simulation study of growth of TiO2 films on different substrates and its applications

NASA Astrophysics Data System (ADS)

Ghogare, Trupti T.; Kartha, Moses J.; Kendre, Subhash D.; Pathan, Habib M.

2018-04-01

Monte-Carlo Ballistic Deposition simulations have done on substrates with different initial roughness. The grown films were observed to be porous. The initial growths of the films with seed like initiations are observed for substrate with high initial roughness. In order to confirm this effect TiO2 films were deposited on different substrates using chemical bath deposition. The surface morphological and optical properties were measured using scanning electron microscopy and a UV-Vis spectrophotometer. Flower like porous structure are obtained on glass substrate and continuous porous morphology is formed on ITO substrate. The morphology of the surfaces was successfully reconstructed and the surface porosity was calculated after digitalising images and reconstructed the surfaces. The TiO2 film formed on ITO is observed to be 10% more porous than on the film formed on glass substrate. Diffusion Limited Aggregation simulations with multiple seeds confirms that the observed flower like structure formed are due to the screening effects of the diffusing ion by already deposited particles.

Electronically transparent graphene replicas of diatoms: a new technique for the investigation of frustule morphology

PubMed Central

Pan, Zhengwei; Lerch, Sarah J. L.; Xu, Liang; Li, Xufan; Chuang, Yen-Jun; Howe, Jane Y.; Mahurin, Shannon M.; Dai, Sheng; Hildebrand, Mark

2014-01-01

The morphogenesis of the silica cell walls (called frustules) of unicellular algae known as diatoms is one of the most intriguing mysteries of the diatoms. To study frustule morphogenesis, optical, electron and atomic force microscopy has been extensively used to reveal the frustule morphology. However, since silica frustules are opaque, past observations were limited to outer and fracture surfaces, restricting observations of interior structures. Here we show that opaque silica frustules can be converted into electronically transparent graphene replicas, fabricated using chemical vapor deposition of methane. Chemical vapor deposition creates a continuous graphene coating preserving the frustule's shape and fine, complicated internal features. Subsequent dissolution of the silica with hydrofluoric acid yields a free-standing replica of the internal and external native frustule morphologies. Electron microscopy renders these graphene replicas highly transparent, revealing previously unobserved, complex, three-dimensional, interior frustule structures, which lend new insights into the investigation of frustule morphogenesis. PMID:25135739

Effect of Eu3+ doping on the structural, morphological and luminescence properties ZnO nanostructures

NASA Astrophysics Data System (ADS)

Vinoditha, U.; Balakrishna, K. M.; Sarojini, B. K.; Narayana, B.; Kumara, K.

2018-05-01

Pure and Eu3+ ions (1, 3, 5 atomic wt%) doped ZnO nanostructures are synthesized by a surfactant assisted hydrothermal method. The effect of doping concentrations on structural, morphological and optical properties of ZnO nanostructures is studied. The XRD analysis shows good crystallinity and the phase purity of the ZnO nanostructures. A shift in the standard Zn-O stretching mode after Eu3+ doping is observed in the FTIR spectra. The images of FESEM demonstrate the morphological variations from hexagonal nanorods to nanoflowers on varying the dopant concentrations. Substitution of Eu3+ ions into Zn2+ sites is confirmed by EDX analysis. The dominance of particle shape over the UV-Visible absorption properties of the prepared samples is noticed. The photoluminescence (PL) emission of undoped and doped ZnO nanostructures show dominant near band edge emission (NBE) in the UV region and minor defect induced deep level emissions in the visible region.

The relationship between morphological changes of lens epithelial cells and intraocular lens optic material.

PubMed

Majima, K

1998-01-01

To examine the morphological changes of lens epithelial cells (LECs) occurring directly beneath and at regions contacting various intraocular lens (IOL) optic materials, human LECs were cultured on human anterior lens capsules and were further incubated upon placing above the cells lens optics made of polymethylmethacrylate, silicone, and soft acrylic material. Observations as to the morphological changes of LECs under phase-contrast microscope and scanning electron microscope were performed on the 14th day of incubation. Gatherings of LECs were observed at regions contacting the soft acrylic material under phase-contrast microscope, and gatherings of LECs were observed accurately at the same regions mentioned above under scanning electron microscope. On the other hand, LECs in contact with two other optic materials did not show morphological changes. The results suggest that LECs attached to and proliferated on not only the anterior lens capsules but also the soft acrylic IOL optics. The model used in this study may be useful in studying the relationship between cellular movement of LECs and IOL optic material.

Phenomenal enhancement of optical nonlinearity in PTZ-I based ZnS/ZnSe nanocomposites

NASA Astrophysics Data System (ADS)

Divyasree, M. C.; Shiju, E.; Vijisha, M. V.; Ramesan, M. T.; Chandrasekharan, K.

2018-05-01

The enhanced nonlinear optical properties of phenothiazine-iodine (PTZ-I) charge transfer complex (CTC) on composite formation with ZnS/ZnSe nanostructures are reported. The interaction between the components was confirmed by the FTIR spectra. Structural and morphological changes on nanocomposite formation were analyzed by scanning electron microscopy and X-ray diffraction spectra. The absorption and emission features of both the nanocomposites and their constituent components were studied. Nonlinear optical properties of all the samples in nanosecond regime were investigated by the Z-scan technique using Nd: YAG laser with 532 nm wavelength and 7 ns pulse width. The optical nonlinearity of PTZ-I CTC was found to be improved considerably on composite formation and the new systems can be proposed as excellent candidates for photonic devices. Enhanced optical nonlinearity of the composites could be attributed to charge/energy transfer mechanism between PTZ-I CTC and the nanostructures.

Characterization of AlF3 thin films at 193 nm by thermal evaporation

NASA Astrophysics Data System (ADS)

Lee, Cheng-Chung; Liu, Ming-Chung; Kaneko, Masaaki; Nakahira, Kazuhide; Takano, Yuuichi

2005-12-01

Aluminum fluoride (AlF3) was deposited by a resistive heating boat. To obtain a low optical loss and high laser-induced damage threshold (LIDT) at 193 nm, the films were investigated under different substrate temperatures, deposition rates, and annealing after coating. The optical property (the transmittance, refractive index, extinction coefficient, and optical loss) at 193 nm, microstructure (the cross-sectional morphology, surface roughness, and crystalline structure), mechanical property (stress), and LIDT of AlF3 thin films have been studied. AlF3 thin films deposited at a high substrate temperature and low deposition rate showed a lower optical loss. The highest LIDT occurred at the substrate temperature of 150 °C. The LIDT of the films prepared at a deposition rate of 2 Å/s was higher than that at other deposition rates. The annealing process did not influence the optical properties too much, but it did increase the LIDT and stress.

Characterization of AlF3 thin films at 193 nm by thermal evaporation.

PubMed

Lee, Cheng-Chung; Liu, Ming-Chung; Kaneko, Masaaki; Nakahira, Kazuhide; Takano, Yuuichi

2005-12-01

Aluminum fluoride (AlF3) was deposited by a resistive heating boat. To obtain a low optical loss and high laser-induced damage threshold (LIDT) at 193 nm, the films were investigated under different substrate temperatures, deposition rates, and annealing after coating. The optical property (the transmittance, refractive index, extinction coefficient, and optical loss) at 193 nm, microstructure (the cross-sectional morphology, surface roughness, and crystalline structure), mechanical property (stress), and LIDT of AlF3 thin films have been studied. AlF3 thin films deposited at a high substrate temperature and low deposition rate showed a lower optical loss. The highest LIDT occurred at the substrate temperature of 150 degrees C. The LIDT of the films prepared at a deposition rate of 2 A/s was higher than that at other deposition rates. The annealing process did not influence the optical properties too much, but it did increase the LIDT and stress.

Optical and morphological properties of Cirrus clouds determined by the high spectral resolution lidar during FIRE

NASA Technical Reports Server (NTRS)

Grund, Christian John; Eloranta, Edwin W.

1990-01-01

Cirrus clouds reflect incoming solar radiation and trap outgoing terrestrial radiation; therefore, accurate estimation of the global energy balance depends upon knowledge of the optical and physical properties of these clouds. Scattering and absorption by cirrus clouds affect measurements made by many satellite-borne and ground based remote sensors. Scattering of ambient light by the cloud, and thermal emissions from the cloud can increase measurement background noise. Multiple scattering processes can adversely affect the divergence of optical beams propagating through these clouds. Determination of the optical thickness and the vertical and horizontal extent of cirrus clouds is necessary to the evaluation of all of these effects. Lidar can be an effective tool for investigating these properties. During the FIRE cirrus IFO in Oct. to Nov. 1986, the High Spectral Resolution Lidar (HSRL) was operated from a rooftop site on the campus of the University of Wisconsin at Madison, Wisconsin. Approximately 124 hours of fall season data were acquired under a variety of cloud optical thickness conditions. Since the IFO, the HSRL data set was expanded by more than 63.5 hours of additional data acquired during all seasons. Measurements are presented for the range in optical thickness and backscattering phase function of the cirrus clouds, as well as contour maps of extinction corrected backscatter cross sections indicating cloud morphology. Color enhanced images of range-time indicator (RTI) displays a variety of cirrus clouds with approximately 30 sec time resolution are presented. The importance of extinction correction on the interpretation of cloud height and structure from lidar observations of optically thick cirrus are demonstrated.

Study of cobalt effect on structural and optical properties of Dy doped ZnO nanoparticles

NASA Astrophysics Data System (ADS)

Kumar, Pawan; Pandey, Praveen C.

2018-05-01

The present study has been carried out to investigate the effect of Co doping on structural and optical properties of Dy doped ZnO nanoparticles. We have prepared pure Zinc oxide, Dy (1%) doped ZnO and Dy (1%) doped ZnO co-doped with Co(2%) with the help of simple sol-gel combustion method. The structural analysis carried out using X-ray diffraction spectra (XRD) indicates substitution of Dy and Co at Zn site of ZnO crystal structure and hexagonal crystal structure without any secondary phase formation in all the samples. The surface morphology was analyzed by transmission electron microscopy (TEM). Absorption study indicates that Dy doping causes a small shift in band edge, while Co co-doping results significant change is absorption edge as well as introduce defect level absorption in the visible region. The band gap of samples decreases due to Dy and Co doping, which can be attributed to defect level formation below the conduction band in the system.

Fabrication and Characterization of Large-Area Unpatterned and Patterned Plasmonic Gold Nanostructures

NASA Astrophysics Data System (ADS)

Do, Minh Thanh; Tong, Quang Cong; Luong, Mai Hoang; Lidiak, Alexander; Ledoux-Rak, Isabelle; Lai, Ngoc Diep

2016-05-01

We report fabrication of Au nanoisland films on different substrates by thermally annealing a sputtered Au nanolayer and investigation of their structure, morphology, and optical properties. It was found that high-temperature annealing leads to transformation of the initial, continuous film into the forms of hillock and isolated island film. The final nanoisland films exhibit remarkably enhanced and localized plasmon resonance spectra with respect to the original sputtered film. The strong dependence of the resonance band spectra of the resulting structures on the annealing temperature and supporting substrate is presented and analyzed, suggesting that both of these factors could be used to tune the optical spectroscopic properties of such structures. Moreover, we propose and demonstrate a novel and effective approach for fabrication of patterned Au structures by thermally annealing the Au layer deposited onto modulated-surface substrates. The experimental results indicate that this method could become a promising approach for manufacturing plasmonic array structures, which have been extensively investigated and widely applied in many fields.

Synthesis, electronic structure, molecular packing/morphology evolution, and carrier mobilities of pure oligo-/poly(alkylthiophenes).

PubMed

Zhang, Lei; Colella, Nicholas S; Liu, Feng; Trahan, Stephan; Baral, Jayanta K; Winter, H Henning; Mannsfeld, Stefan C B; Briseno, Alejandro L

2013-01-16

Monodispersed conjugated oligothiophenes are receiving attention in fundamental and applied science due to their interesting optical, optoelectronic, and charge transport properties. These "low molecular weight" polymers serve as model structures for the corresponding polymer analogues, which are inherently polydispersed. Here we report the synthesis, electronic structure, molecular packing/morphology, and charge transport properties of monodispersed oligothiophenes with up to six didodecylquaterthiophene (DDQT) building block repeat units (i.e., 24 thiophene units). At the point where the effective conjugation length is reached, the electronic structure showed convergence behavior to the corresponding polymer, poly(3,3"-didodecyl-quaterthiophene) (PQT-12). X-ray crystal structure analysis of the dimer (DDQT-2) showed that terminal thiophenes exhibit syn-conformations, similar to the terminal syn-conformations observed in the trimer (DDQT-3). The dimer also exhibits a rare bending of the terminal alkyl side chains in order to prevent steric hindrance with neighboring hydrogens attached to core thiophenes. Grazing incidence X-ray scattering measurements revealed a morphology evolution from small molecule-like packing to polymer-like packing in thin films, with a morphology transition occurring near the effective conjugation length. Charge transport measurements showed a mobility increase with decreasing chain length. We correlated the molecular packing and morphology to charge transport and determined that carrier mobilities are most sensitive to crystallinity and crystal grain misorientation. This indicates that molecular weight is not a decisive factor for improved carrier mobility in the low molecular weight region, but rather the degree in crystallinity and in-plane crystal orientation. These results represent a fundamental advancement in understanding the relationship between conjugation length and carrier mobilities in oligothiophene semiconductors.

Morphology and Structure of Ultraluminous Infrared Galaxies at z ∼ 2 in the EGS Field

NASA Astrophysics Data System (ADS)

Fang, Guan-Wen; Ma, Zhong-Yang; Chen, Yang; Kong, Xu

2015-04-01

Using the high-resolution F160W images observed by the HST WFC3 (Hubble Space Telescope Wide Field Camera 3) in the CANDELS-EGS (Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey-Extended Groth Strip) field, we have studied the morphological and structural features of 9 ultraluminous infrared galaxies (ULIRGs) at z ∼ 2. We find a wide range of morphological diversity for these ULIRGs, from ellipsoids to multiple bright nuclei or diffuse structures, e.g., the double nuclei, gaseous bridges, dual asym- metries, irregular or elliptical structures. In order to study the morphology of these ULIRGs quantitatively, their morphological parameters (the Gini coeffcient G and moment index M20) are measured in the rest-frame optical wave- band. Compared with the low-redshift counterparts, the high-redshift ULIRGs show a smaller value of G and a larger value of M20, indicating a less concen- tricity and a larger asymmetry of the stellar population distribution in these ULIRGs. Based on a 2-D fitting of the brightness profiles of these ULIRGs, we have derived their effective radii, which are distributed in a range from 2.4 to kpc, with a mean value of (3.9 ± 1.1) kpc. Moreover, we find that in average the sizes of the high-redshift ULIRGs are one to two times smaller than those of the nearby star-forming galaxies of analogous stellar mass. Our results are consistent with those of other studies under the similar conditions of redshift and infrared luminosity.

Au nanorice assemble electrolytically into mesostars.

PubMed

Bardhan, Rizia; Neumann, Oara; Mirin, Nikolay; Wang, Hui; Halas, Naomi J

2009-02-24

Star-shaped mesotructures are formed when an aqueous suspension of Au nanorice particles, which consist of prolate hematite cores and a thin Au shell, is subjected to an electric current. The nanorice particles assemble to form hyperbranched micrometer-scale mesostars. To our knowledge, this is the first reported observation of nanoparticle assembly into larger ordered structures under the influence of an electrochemical process (H(2)O electrolysis). The assembly is accompanied by significant modifications in the morphology, dimensions, chemical composition, crystallographic structure, and optical properties of the constituent nanoparticles.

Metallurgical characterization of the fracture of several high strength aluminum alloys

NASA Technical Reports Server (NTRS)

Bhandarkar, M. D.; Lisagor, W. B.

1977-01-01

The fracture behavior for structural aluminum alloys (2024, 6061, 7075, and 7178) was examined in selected heat treatments. The investigation included tensile, shear, and precracked notch-bend specimens fractured at ambient temperature under monotonic loading. Specimens were obtained from thin sheets and thick plates and were tested in longitudinal and transverse orientations at different strain rates. Microstructures of alloys were examined using the optical microscope and the scanning electron microscope with associated energy dispersive X ray chemical analysis. Several different types of second phase particles, some not reported by other investigators, were identified in the alloys. Fracture morphology was related to microstructural variables, test variables, and type of commercial product. Specimen orientation examined in the present investigation had little effect on fracture morphology. Test strain rate changes resulted in some change in shear fracture morphology, but not in fracture morphology of tensile specimens.

Capturing the Surface Texture and Shape of Pollen: A Comparison of Microscopy Techniques

PubMed Central

Sivaguru, Mayandi; Mander, Luke; Fried, Glenn; Punyasena, Surangi W.

2012-01-01

Research on the comparative morphology of pollen grains depends crucially on the application of appropriate microscopy techniques. Information on the performance of microscopy techniques can be used to inform that choice. We compared the ability of several microscopy techniques to provide information on the shape and surface texture of three pollen types with differing morphologies. These techniques are: widefield, apotome, confocal and two-photon microscopy (reflected light techniques), and brightfield and differential interference contrast microscopy (DIC) (transmitted light techniques). We also provide a first view of pollen using super-resolution microscopy. The three pollen types used to contrast the performance of each technique are: Croton hirtus (Euphorbiaceae), Mabea occidentalis (Euphorbiaceae) and Agropyron repens (Poaceae). No single microscopy technique provided an adequate picture of both the shape and surface texture of any of the three pollen types investigated here. The wavelength of incident light, photon-collection ability of the optical technique, signal-to-noise ratio, and the thickness and light absorption characteristics of the exine profoundly affect the recovery of morphological information by a given optical microscopy technique. Reflected light techniques, particularly confocal and two-photon microscopy, best capture pollen shape but provide limited information on very fine surface texture. In contrast, transmitted light techniques, particularly differential interference contrast microscopy, can resolve very fine surface texture but provide limited information on shape. Texture comprising sculptural elements that are spaced near the diffraction limit of light (∼250 nm; NDL) presents an acute challenge to optical microscopy. Super-resolution structured illumination microscopy provides data on the NDL texture of A. repens that is more comparable to textural data from scanning electron microscopy than any other optical microscopy technique investigated here. Maximizing the recovery of morphological information from pollen grains should lead to more robust classifications, and an increase in the taxonomic precision with which ancient vegetation can be reconstructed. PMID:22720050

Synthesis of non-hydrazine solution processed Cu2(ZnSn)S4 thin films for solar cells applications

NASA Astrophysics Data System (ADS)

Gupta, Indu; Gupta, Preeti; Mohanty, Bhaskar Chandra

2017-05-01

Solution processing provides a versatile and inexpensive means to prepare Cu2ZnSnS4 (CZTS) thin films for photovoltaic applications. Differently with the reported growth of CZTS films from hydrazine based toxic solutions, we demonstrate a simple non-toxic ethanol based solution approach to synthesize the films. Using the chemical bath deposition (CBD) method, the CZTS thin films were grown from metal salts (copper chloride, zinc chloride, and tin chloride) in ethanol and monoethanol amine (MEA) and thioacetamide in ethanol as sulfur source in a single dip followed by sulfurization. The structure, composition, morphology and optical properties of the CZTS film were studied by X-ray diffraction, scanning electron microscopy and UV-vis spectroscopy. The results revealed that a post-deposition sulfurization is necessary to the phase formation and among all, sulfurization at 450°C for 60 min yielded phase pure CZTS films having kesterite structure, relatively compact morphology and an optical band gap of ˜1.52 eV indicating its suitability for solar cell applications. The results clearly validate the CBD method as a potential scalable route of preparation of CZTS thin films.

Facile preparation of hierarchical nanostructured CuInS2 counter electrodes for dye-sensitized solar cells

NASA Astrophysics Data System (ADS)

Dhas, C. Ravi; Christy, A. Jennifer; Venkatesh, R.; Santhoshi Monica, S. Esther; Panda, Subhendu K.; Subramanian, B.; Ravichandran, K.; Sudhagar, P.; Ezhil Raj, A. Moses

2017-12-01

CuInS2 (CIS) thin films have been synthesized onto the glass substrates for different solvent volumes (10, 30, 50 and 70 ml) by nebulizer spray technique. The effect of solvent volume on the structural, morphological, compositional, optical and electrical properties of CIS thin films has been investigated. X-ray diffraction patterns suggest that the obtained CIS films are polycrystalline with the tetragonal structure. The surface morphology of the prepared CIS films purely depends on the solvent volume. The elemental quantitative investigation and the stoichiometric ratio of the CIS thin films were verified from XPS and EDS. High absorbance with the optical band gap of 1.13 eV was obtained at the higher solvent volume. All the deposited CIS thin films exhibited p-type semiconducting behavior with the high electrical conductivity and carrier concentration. CIS thin films deposited onto the FTO substrate were used as a counter electrode (CE) in dye-sensitized solar cells. CIS CEs possessed high electrocatalytic behavior and fast electron charge transfer at the CE/electrolyte interface. The CIS CE prepared using 50 ml solvent volume generated high energy conversion efficiency of about 3.25%.

Structural, morphological, and optical properties of TiO2 thin films synthesized by the electro phoretic deposition technique.

PubMed

Ghrairi, Najla; Bouaicha, Mongi

2012-07-01

In this work, we report the structural, morphological, and optical properties of TiO2 thin films synthesized by the electro phoretic deposition technique. The TiO2 film was formed on a doped fluorine tin oxide (SnO2:F, i.e., FTO) layer and used as a photo electrode in a dye solar cell (DSC). Using spectroscopic ellipsometry measurements in the 200 to 800 nm wavelengths domain, we obtain a thickness of the TiO2 film in the range of 70 to 80 nm. Characterizations by X-ray diffraction and atomic force microscopy (AFM) show a polycrystalline film. In addition, AFM investigation shows no cracks in the formed layer. Using an ultraviolet-visible near-infrared spectrophotometer, we found that the transmittance of the TiO2 film in the visible domain reaches 75%. From the measured current-voltage or I-V characteristic under AM1.5 illumination of the formed DSC, we obtain an open circuit voltage Voc = 628 mV and a short circuit current Isc = 22.6 μA, where the surface of the formed cell is 3.14 cm2.

Structural, morphological, and optical properties of TiO2 thin films synthesized by the electro phoretic deposition technique

PubMed Central

2012-01-01

In this work, we report the structural, morphological, and optical properties of TiO2 thin films synthesized by the electro phoretic deposition technique. The TiO2 film was formed on a doped fluorine tin oxide (SnO2:F, i.e., FTO) layer and used as a photo electrode in a dye solar cell (DSC). Using spectroscopic ellipsometry measurements in the 200 to 800 nm wavelengths domain, we obtain a thickness of the TiO2 film in the range of 70 to 80 nm. Characterizations by X-ray diffraction and atomic force microscopy (AFM) show a polycrystalline film. In addition, AFM investigation shows no cracks in the formed layer. Using an ultraviolet–visible near-infrared spectrophotometer, we found that the transmittance of the TiO2 film in the visible domain reaches 75%. From the measured current–voltage or I-V characteristic under AM1.5 illumination of the formed DSC, we obtain an open circuit voltage Voc = 628 mV and a short circuit current Isc = 22.6 μA, where the surface of the formed cell is 3.14 cm2. PMID:22747886

Effects of polymer surface energy on morphology and properties of silver nanowire fabricated via nanoimprint and E-beam evaporation

NASA Astrophysics Data System (ADS)

Zhao, Zhi-Jun; Hwang, Soon Hyoung; Jeon, Sohee; Jung, Joo-Yun; Lee, Jihye; Choi, Dae-Geun; Choi, Jun-Hyuk; Park, Sang-Hu; Jeong, Jun-Ho

2017-10-01

In this paper, we demonstrate that use of different nanoimprint resins as a polymer pattern has a significant effect on the morphology of silver (Ag) nanowires deposited via an E-beam evaporator. RM-311 and Ormo-stamp resins are chosen as a polymer pattern to form a line with dimensions of width (100 nm) × space (100 nm) × height (120 nm) by using nanoimprint lithography (NIL). Their contact angles are then measured to evaluate their surface energies. In order to compare the properties of the Ag nanowires deposited on the various polymer patterns with different surface energies, hydrophobic surface treatment of the polymer pattern surface is implemented using self-assembled monolayers. In addition, gold and aluminum nanowires are fabricated for comparison with the Ag nanowires, with the differences in the nanowire morphologies being determined by the different atomic properties. The monocrystalline and polycrystalline structures of the various Ag nanowire formations are observed using transmission electron microscopy. In addition, the melting temperatures and optical properties of four kinds of Ag nanowire morphologies deposited on various polymer patterns are evaluated using a hot plate and an ultraviolet-visible (UV-vis) spectrometer, respectively. The results indicate that the morphology of the Ag nanowire determines the melting temperature and the transmission. We believe that these findings will greatly aid the development of NIL, along with physical evaporation and chemical deposition techniques, and will be widely employed in optics, biology, and surface wettability applications.

Morphological and topographical appearance of microaneurysms on optical coherence tomography angiography.

PubMed

Schreur, Vivian; Domanian, Artin; Liefers, Bart; Venhuizen, Freerk G; Klevering, B Jeroen; Hoyng, Carel B; de Jong, Eiko K; Theelen, Thomas

2018-06-20

To investigate retinal microaneurysms in patients with diabetic macular oedema (DME) by optical coherence tomography angiography (OCTA) according to their location and morphology in relationship to their clinical properties, leakage on fundus fluorescein angiography (FFA) and retinal thickening on structural OCT. OCTA and FFA images of 31 eyes of 24 subjects were graded for the presence of microaneurysms. The topographical and morphological appearance of microaneurysms on OCTA was evaluated and classified. For each microaneurysm, the presence of focal leakage on FFA and associated retinal thickening on OCT was determined. Of all microaneurysms flagged on FFA, 295 out of 513 (58%) were also visible on OCTA. Microaneurysms with focal leakage and located in a thickened retinal area were more likely to be detected on OCTA than not leaking microaneurysms in non-thickened retinal areas (p=0.001). Most microaneurysms on OCTA were seen in the intermediate (23%) and deep capillary plexus (22%). Of all microaneurysms visualised on OCTA, saccular microaneurysms were detected most often (31%), as opposed to pedunculated microaneurysms (9%). Irregular, fusiform and mixed fusiform/saccular-shaped microaneurysms had the highest likeliness to leak and to be located in thickened retinal areas (p<0.001, p<0.001 and p=0.001). Retinal microaneurysms in DME could be classified topographically and morphologically by OCTA. OCTA detected less microaneurysms than FFA, and this appeared to be dependent on leakage activity and retinal thickening. Morphological appearance of microaneurysms (irregular, fusiform and mixed saccular/fusiform) was associated with increased leakage activity and retinal thickening.

Bimetallic clustered thin films with variable electro-optical properties

NASA Astrophysics Data System (ADS)

Antipov, A.; Bukharov, D.; Arakelyan, S.; Osipov, A.; Lelekova, A.

2018-01-01

The drop deposition of colloidal nanoparticles was performed from water-based colloidal solutions. The proposed procedure is based on the agglomeration of colloidal particles in laser-assisted evaporation processes. The evaporation process was resulted in the formation of clustered thin films on a glass substrate. In the experiments with bimetallic Au:Ag solutions, the clustered films are grown, the formation of the clustered films with the average height of 100 nm was achieved. Optical properties of the deposited structures were investigated experimentally. It is shown that the obtained films may become transparent and its properties are defined by its morphology.

Optical absorption and scattering spectra of pathological stomach tissues

NASA Astrophysics Data System (ADS)

Giraev, K. M.; Ashurbekov, N. A.; Lakhina, M. A.

2011-03-01

Diffuse reflection spectra of biotissues in vivo and transmission and reflection coefficients for biotissues in vitro are measured over 300-800 nm. These data are used to determine the spectral absorption and scattering indices and the scattering anisotropy factor for stomach mucous membranes under normal and various pathological conditions (chronic atrophic and ulcerous defects, malignant neoplasms). The most importan tphysiological (hemodynamic and oxygenation levels) and structural-morphological (scatterer size and density) parameters are also determined. The results of a morphofunctional study correlate well with the optical properties and are consistent with data from a histomorphological analysis of the corresponding tissues.

In vivo multimodal nonlinear optical imaging of mucosal tissue

NASA Astrophysics Data System (ADS)

Sun, Ju; Shilagard, Tuya; Bell, Brent; Motamedi, Massoud; Vargas, Gracie

2004-05-01

We present a multimodal nonlinear imaging approach to elucidate microstructures and spectroscopic features of oral mucosa and submucosa in vivo. The hamster buccal pouch was imaged using 3-D high resolution multiphoton and second harmonic generation microscopy. The multimodal imaging approach enables colocalization and differentiation of prominent known spectroscopic and structural features such as keratin, epithelial cells, and submucosal collagen at various depths in tissue. Visualization of cellular morphology and epithelial thickness are in excellent agreement with histological observations. These results suggest that multimodal nonlinear optical microscopy can be an effective tool for studying the physiology and pathology of mucosal tissue.

Optical and electrical properties of p-type transparent conducting CuAlO2 thin film synthesized by reactive radio frequency magnetron sputtering technique

NASA Astrophysics Data System (ADS)

Saha, B.; Thapa, R.; Jana, S.; Chattopadhyay, K. K.

2010-10-01

Thin films of p-type transparent conducting CuAlO2 have been synthesized through reactive radio frequency magnetron sputtering on silicon and glass substrates at substrate temperature 300°C. Reactive sputtering of a target fabricated from Cu and Al powder (1:1.5) was performed in Ar+O2 atmosphere. The deposition parameters were optimized to obtain phase pure, good quality CuAlO2 thin films. The films were characterized by studying their structural, morphological, optical and electrical properties.

Effect of Sn doping on structural, mechanical, optical and electrical properties of ZnO nanoarrays prepared by sol-gel and hydrothermal process

NASA Astrophysics Data System (ADS)

Agarwal, Manish Baboo; Sharma, Akash; Malaidurai, M.; Thangavel, R.

2018-05-01

Undoped and Sn doped Zinc oxide nanorods were prepared by two step process: initially growth of seed layers by sol-gel spin coating technique and then zinc oxide nanorods by hydrothermal process using the precursors zinc nitrate hexahydrate, hexamine and tin chloride. The effects on the electrical, optical, mechanical and structural properties for various Sn concentrations were studied. The crystalline phase determination from X-ray diffraction (XRD) confirms that Sn doped ZnO nanorods have hexagonal wurtzite structure. The variations of stress and strain with different doping concentration of Sn in ZnO nanorods were studied. The doping effect on electrical properties and optical bandgap is estimated by current voltage characteristics and absorbance spectra respectively. The surface morphology was studied with field emission scanning electron microscope (FESEM), which shows that the formation of hexagonal nanorods arrays with increasing Sn concentration. The calculated value of Young's modulus of elasticity (Y) for all the samples remains same. These results can be used in optoelectronic devices.

Porous Silicon—A Versatile Host Material

PubMed Central

Granitzer, Petra; Rumpf, Klemens

2010-01-01

This work reviews the use of porous silicon (PS) as a nanomaterial which is extensively investigated and utilized for various applications, e.g., in the fields of optics, sensor technology and biomedicine. Furthermore the combination of PS with one or more materials which are also nanostructured due to their deposition within the porous matrix is discussed. Such nanocompounds offer a broad avenue of new and interesting properties depending on the kind of involved materials as well as on their morphology. The filling of the pores performed by electroless or electrochemical deposition is described, whereas different morphologies, reaching from micro- to macro pores are utilized as host material which can be self-organized or fabricated by prestructuring. For metal-deposition within the porous structures, both ferromagnetic and non-magnetic metals are used. Emphasis will be put on self-arranged mesoporous silicon, offering a quasi-regular pore arrangement, employed as template for filling with ferromagnetic metals. By varying the deposition parameters the precipitation of the metal structures within the pores can be tuned in geometry and spatial distribution leading to samples with desired magnetic properties. The correlation between morphology and magnetic behaviour of such semiconducting/magnetic systems will be determined. Porous silicon and its combination with a variety of filling materials leads to nanocomposites with specific physical properties caused by the nanometric size and give rise to a multiplicity of potential applications in spintronics, magnetic and magneto-optic devices, nutritional food additives as well as drug delivery.

Highly efficient upconversion luminescence in hexagonal NaYF4:Yb3+, Er3+ nanocrystals synthesized by a novel reverse microemulsion method

NASA Astrophysics Data System (ADS)

Gunaseelan, M.; Yamini, S.; Kumar, G. A.; Senthilselvan, J.

2018-01-01

A new reverse microemulsion system is proposed for the first time to synthesize NaYF4:Yb,Er nanocrystals, which demonstrated high upconversion emission in 550 and 662 nm at 980 nm diode laser excitation. The reverse microemulsion (μEs) system is comprised of CTAB and oleic acid as surfactant and 1-butanol co-surfactant and isooctane oil phase. The surfactant to water ratio is able to tune the microemulsion droplet size from 14 to 220 nm, which eventually controls the crystallinity and particulate morphology of NaYF4:Yb,Er. Also, the microemulsion precursor and calcination temperature plays certain role in transforming the cubic NaYF4:Yb,Er to highly luminescent hexagonal crystal structured upconversion material. Single phase hexagonal NaYF4:YbEr nanorod prepared by water-in-oil reverse microemulsion (μEs) gives intense red upconversion emission. Both nanosphere and nanorod shaped NaYF4:Yb,Er was obtained, but nanorod morphology resulted an enhanced upconversion luminescence. The structural, morphological, thermal and optical luminescence properties of the NaYF4:Yb,Er nanoparticles are discussed in detail by employing powder X-ray diffraction, dynamic light scattering, high resolution electron microscopy, TGA-DTA, UV-DRS, FTIR and photoluminescence spectroscopy. Intense upconversion emission achieved in the microemulsion synthesized NaYF4:Yb3+,Er3+ nanocrystal can make it as useful optical phosphor for solar cell applications.

Experimental investigation of instability in optical and morphological properties of percolated gold thin film during ambient aging

NASA Astrophysics Data System (ADS)

Sudheer, Mukherjee, C.; Rai, S. K.; Rai, V. N.; Srivastava, A. K.

2018-04-01

Instability in morphological and optical properties of sputtered grown percolated gold (Au) film has been experimentally investigated during ambient aging. Optical absorbance of the film recorded at various stage of aging shows huge variation in the spectra. A schematic is drawn to explain aging-assist evolution in the morphology (dewetting) and correlated with the variation in optical properties. The validity of model is confirmed by X-ray reflectivity (XRR) techniques, performed for both as-deposited and aged samples. Furthermore, change in the color of Au thin film with aging also seen in the photographic images of the samples that also support the absorbance and XRR results.

Speckle-modulating optical coherence tomography in living mice and humans.

PubMed

Liba, Orly; Lew, Matthew D; SoRelle, Elliott D; Dutta, Rebecca; Sen, Debasish; Moshfeghi, Darius M; Chu, Steven; de la Zerda, Adam

2017-06-20

Optical coherence tomography (OCT) is a powerful biomedical imaging technology that relies on the coherent detection of backscattered light to image tissue morphology in vivo. As a consequence, OCT is susceptible to coherent noise (speckle noise), which imposes significant limitations on its diagnostic capabilities. Here we show speckle-modulating OCT (SM-OCT), a method based purely on light manipulation that virtually eliminates speckle noise originating from a sample. SM-OCT accomplishes this by creating and averaging an unlimited number of scans with uncorrelated speckle patterns without compromising spatial resolution. Using SM-OCT, we reveal small structures in the tissues of living animals, such as the inner stromal structure of a live mouse cornea, the fine structures inside the mouse pinna, and sweat ducts and Meissner's corpuscle in the human fingertip skin-features that are otherwise obscured by speckle noise when using conventional OCT or OCT with current state of the art speckle reduction methods.

Effect of dopent on the structural and optical properties of ZnS thin film as a buffer layer in solar cell application

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vashistha, Indu B., E-mail: indu-139@yahoo.com; Sharma, S. K.; Sharma, Mahesh C.

2015-08-28

In order to find the suitable alternative of toxic CdS buffer layer, deposition of pure ZnS and doped with Al by chemical bath deposition method have been reported. Further as grown pure and doped thin films have been annealed at 150°C. The structural and surface morphological properties have been characterized by X-Ray diffraction (XRD) and Atomic Force Microscope (AFM).The XRD analysis shows that annealed thin film has been polycrystalline in nature with sphalerite cubic crystal structure and AFM images indicate increment in grain size as well as growth of crystals after annealing. Optical measurement data give band gap of 3.5more » eV which is ideal band gap for buffer layer for solar cell suggesting that the obtained ZnS buffer layer is suitable in a low-cost solar cell.« less

Speckle-modulating optical coherence tomography in living mice and humans

PubMed Central

Liba, Orly; Lew, Matthew D.; SoRelle, Elliott D.; Dutta, Rebecca; Sen, Debasish; Moshfeghi, Darius M.; Chu, Steven; de la Zerda, Adam

2017-01-01

Optical coherence tomography (OCT) is a powerful biomedical imaging technology that relies on the coherent detection of backscattered light to image tissue morphology in vivo. As a consequence, OCT is susceptible to coherent noise (speckle noise), which imposes significant limitations on its diagnostic capabilities. Here we show speckle-modulating OCT (SM-OCT), a method based purely on light manipulation that virtually eliminates speckle noise originating from a sample. SM-OCT accomplishes this by creating and averaging an unlimited number of scans with uncorrelated speckle patterns without compromising spatial resolution. Using SM-OCT, we reveal small structures in the tissues of living animals, such as the inner stromal structure of a live mouse cornea, the fine structures inside the mouse pinna, and sweat ducts and Meissner’s corpuscle in the human fingertip skin—features that are otherwise obscured by speckle noise when using conventional OCT or OCT with current state of the art speckle reduction methods. PMID:28632205

Speckle-modulating optical coherence tomography in living mice and humans

NASA Astrophysics Data System (ADS)

Liba, Orly; Lew, Matthew D.; Sorelle, Elliott D.; Dutta, Rebecca; Sen, Debasish; Moshfeghi, Darius M.; Chu, Steven; de La Zerda, Adam

2017-06-01

Optical coherence tomography (OCT) is a powerful biomedical imaging technology that relies on the coherent detection of backscattered light to image tissue morphology in vivo. As a consequence, OCT is susceptible to coherent noise (speckle noise), which imposes significant limitations on its diagnostic capabilities. Here we show speckle-modulating OCT (SM-OCT), a method based purely on light manipulation that virtually eliminates speckle noise originating from a sample. SM-OCT accomplishes this by creating and averaging an unlimited number of scans with uncorrelated speckle patterns without compromising spatial resolution. Using SM-OCT, we reveal small structures in the tissues of living animals, such as the inner stromal structure of a live mouse cornea, the fine structures inside the mouse pinna, and sweat ducts and Meissner's corpuscle in the human fingertip skin--features that are otherwise obscured by speckle noise when using conventional OCT or OCT with current state of the art speckle reduction methods.

Effect of swift heavy ion irradiation on structural, optical and electrical properties of spray deposited CdO thin films

NASA Astrophysics Data System (ADS)

Kumaravel, R.; Ramamurthi, K.; Sulania, Indra; Asokan, K.; Kanjilal, D.; Avasti, D. K.; Kulria, P. K.

2011-03-01

Thin films of cadmium oxide have been deposited on glass substrate using the spray pyrolysis technique. The prepared films are irradiated with 120 MeV swift Ag 9+ ions for fluence in the range of 1×10 12-1×10 13 ions cm -2 and their structural properties are studied by glancing angle X-ray diffraction. The films exhibit cubic crystal structure. It is observed that the irradiated films are amorphized at higher fluence of 1×10 13 ions cm -2. Surface morphology studies by atomic force microscopy show that the pristine film has a surface roughness of 39.80 nm and it decreases with increase in ion fluence. The optical transmittance spectra show a decrease in transmittance with increase in fluence and the band gap value also decreases due to irradiation.

Role of Bi3+ substitution on structural, magnetic and optical properties of cobalt spinel ferrite

NASA Astrophysics Data System (ADS)

Anjum, Safia; Sehar, Fatima; Awan, M. S.; Zia, Rehana

2016-04-01

Bismuth-doped cobalt ferrite CoBi x Fe(2- x)O4 with x = 0, 0.1,0.2, 0.3, 0.4, 0.5 have been prepared using powder metallurgy route. The structural, morphological, elemental, magnetic and optical properties have been investigated using X-ray diffractometer, Fourier transform infrared spectroscopy, scanning electron microscope, energy dispersive X-rays, vibrating sample magnetometer and ultraviolet-visible spectrometer, respectively. X-ray diffractometer analysis confirms the formation of single-phase cubic spinel structure. As the substitution of larger ionic radii Bi3+ ions increases in cobalt ferrite which is responsible to increase the lattice parameters and decrease the crystallite size. SEM micrographs revealed the spherical shape of the particles with the nonuniform grain boundaries. The saturation magnetization decreases and bandgap energy increases as the concentration of non-magnetic Bi3+ ions increases.

Brain morphology imaging by 3D microscopy and fluorescent Nissl staining.

PubMed

Lazutkin, A A; Komissarova, N V; Toptunov, D M; Anokhin, K V

2013-07-01

Modern optical methods (multiphoton and light-sheet fluorescent microscopy) allow 3D imaging of large specimens of the brain with cell resolution. It is therefore essential to refer the resultant 3D pictures of expression of transgene, protein, and other markers in the brain to the corresponding structures in the atlas. This implies counterstaining of specimens with morphological dyes. However, there are no methods for contrasting large samples of the brain without their preliminary slicing. We have developed a method for fluorescent Nissl staining of whole brain samples. 3D reconstructions of specimens of the hippocampus, olfactory bulbs, and cortex were created. The method can be used for morphological control and evaluation of the effects of various factors on the brain using 3D microscopy technique.

Applicability, usability, and limitations of murine embryonic imaging with optical coherence tomography and optical projection tomography

PubMed Central

Singh, Manmohan; Raghunathan, Raksha; Piazza, Victor; Davis-Loiacono, Anjul M.; Cable, Alex; Vedakkan, Tegy J.; Janecek, Trevor; Frazier, Michael V.; Nair, Achuth; Wu, Chen; Larina, Irina V.; Dickinson, Mary E.; Larin, Kirill V.

2016-01-01

We present an analysis of imaging murine embryos at various embryonic developmental stages (embryonic day 9.5, 11.5, and 13.5) by optical coherence tomography (OCT) and optical projection tomography (OPT). We demonstrate that while OCT was capable of rapid high-resolution live 3D imaging, its limited penetration depth prevented visualization of deeper structures, particularly in later stage embryos. In contrast, OPT was able to image the whole embryos, but could not be used in vivo because the embryos must be fixed and cleared. Moreover, the fixation process significantly altered the embryo morphology, which was quantified by the volume of the eye-globes before and after fixation. All of these factors should be weighed when determining which imaging modality one should use to achieve particular goals of a study. PMID:27375945

An Ultraviolet/Optical Atlas of Bright Galaxies

NASA Astrophysics Data System (ADS)

Marcum, Pamela M.; O'Connell, Robert W.; Fanelli, Michael N.; Cornett, Robert H.; Waller, William H.; Bohlin, Ralph C.; Neff, Susan G.; Roberts, Morton S.; Smith, Andrew M.; Cheng, K.-P.; Collins, Nicholas R.; Hennessy, Gregory S.; Hill, Jesse K.; Hill, Robert S.; Hintzen, Paul; Landsman, Wayne B.; Ohl, Raymond G.; Parise, Ronald A.; Smith, Eric P.; Freedman, Wendy L.; Kuchinski, Leslie E.; Madore, Barry; Angione, Ronald; Palma, Christopher; Talbert, Freddie; Stecher, Theodore P.

2001-02-01

We present wide-field imagery and photometry of 43 selected nearby galaxies of all morphological types at ultraviolet and optical wavelengths. The ultraviolet (UV) images, in two broad bands at 1500 and 2500 Å, were obtained using the Ultraviolet Imaging Telescope (UIT) during the Astro-1 Spacelab mission. The UV images have ~3" resolution, and the comparison sets of ground-based CCD images (in one or more of B, V, R, and Hα) have pixel scales and fields of view closely matching the UV frames. The atlas consists of multiband images and plots of UV/optical surface brightness and color profiles. Other associated parameters, such as integrated photometry and half-light radii, are tabulated. In an appendix, we discuss the sensitivity of different wavebands to a galaxy's star formation history in the form of ``history weighting functions'' and emphasize the importance of UV observations as probes of evolution during the past 10-1000 Myr. We find that UV galaxy morphologies are usually significantly different from visible band morphologies as a consequence of spatially inhomogeneous stellar populations. Differences are quite pronounced for systems in the middle range of Hubble types, Sa through Sc, but less so for ellipticals or late-type disks. Normal ellipticals and large spiral bulges are fainter and more compact in the UV. However, they typically exhibit smooth UV profiles with far-UV/optical color gradients which are larger than any at optical/IR wavelengths. The far-UV light in these cases is probably produced by extreme horizontal branch stars and their descendants in the dominant, low-mass, metal-rich population. The cool stars in the large bulges of Sa and Sb spirals fade in the UV while hot OB stars in their disks brighten, such that their Hubble classifications become significantly later. In the far-UV, early-type spirals often appear as peculiar, ringlike systems. In some spiral disks, UV-bright structures closely outline the spiral pattern; in others, the disks can be much more fragmented and chaotic than at optical wavelengths. Contributions by bright active galactic nuclei (AGNs) to the integrated UV light in our sample range from less than 10% to nearly 100%. A number of systems have unusual UV-bright structures in their inner disks, including rings, compact knots, and starburst nuclei, which could easily dominate the UV light in high-redshift analogs. A significant but variable fraction of the far-UV light in spiral disks is diffuse rather than closely concentrated to star-forming regions. Dust in normal spiral disks does not control UV morphologies, even in some highly inclined disk systems. The heaviest extinction is apparently confined to thin layers and the immediate vicinity of young H II complexes; the UV light emerges from thicker star distributions, regions evacuated of dust by photodestruction or winds, or by virtue of strong dust clumpiness. Only in cases where the dust layers are disturbed does dust appear to be a major factor in UV morphology. The UV-bright plume of M82 indicates that dust scattering of UV photons can be important in some cases. In a companion paper, we discuss far-UV data from the Astro-2 mission and optical comparisons for another 35 galaxies, emphasizing face-on spirals.

Electrically Conductive and Optically Active Porous Silicon Nanowires

PubMed Central

Qu, Yongquan; Liao, Lei; Li, Yujing; Zhang, Hua; Huang, Yu; Duan, Xiangfeng

2009-01-01

We report the synthesis of vertical silicon nanowire array through a two-step metal-assisted chemical etching of highly doped n-type silicon (100) wafers in a solution of hydrofluoric acid and hydrogen peroxide. The morphology of the as-grown silicon nanowires is tunable from solid nonporous nanowires, nonporous/nanoporous core/shell nanowires, and entirely nanoporous nanowires by controlling the hydrogen peroxide concentration in the etching solution. The porous silicon nanowires retain the single crystalline structure and crystallographic orientation of the starting silicon wafer, and are electrically conductive and optically active with visible photoluminescence. The combination of electronic and optical properties in the porous silicon nanowires may provide a platform for the novel optoelectronic devices for energy harvesting, conversion and biosensing. PMID:19807130

The optical properties of α-Fe2O3 nanostructures synthesized with different immersion time

NASA Astrophysics Data System (ADS)

Ahmad, W. R. W.; Mamat, M. H.; Zoolfakar, A. S.; Khusaimi, Z.; Yusof, M. M.; Ismail, A. S.; Saidi, S. A.; Rusop, M.

2018-05-01

In this study, nanostructured hematite (α-Fe2O3) thin films have been prepared successfully by sonicated immersion method on fluorine-doped tin oxide (FTO) coated glass substrate. The effect of the immersion time on the structural and optical properties of α-Fe2O3 nanostructure were investigated for a variation of immersion time ranging from 1 to 4 hour. From the characterization results, the surface morphology of the sample prepared in 4 hours immersion process has exhibited highest porosity, and the highest absorbance properties were found in the same sample. These results suggest that the different time duration during immersion process play important roles in optical properties of α-Fe2O3 nanostructures.

Synthesis and characterization of cobalt doped nickel oxide thin films by spray pyrolysis method

NASA Astrophysics Data System (ADS)

Sathisha, D.; Naik, K. Gopalakrishna

2018-05-01

Cobalt (Co) doped nickel oxide (NiO) thin films were deposited on glass substrates at a temperature of about 400 °C by spray pyrolysis method. The effect of Co doping concentration on structural, optical and compositional properties of NiO thin films was investigated. X-ray diffraction result shows that the deposited thin films are polycrystalline in nature. Surface morphologies of the deposited thin films were observed by FESEM and AFM. EDS spectra showed the incorporation of Co dopants in NiO thin films. Optical properties of the grown thin films were characterized by UV-visible spectroscopy. It was found that the optical band gap energy and transmittance of the films decrease with increasing Co doping concentration.

Investigation of plasma dynamics during the growth of amorphous titanium dioxide thin films

NASA Astrophysics Data System (ADS)

Kim, Jin-Soo; Jee, Hyeok; Yu, Young-Hun; Seo, Hye-Won

2018-06-01

We have grown amorphous titanium dioxide thin films by reactive DC sputtering method using a different argon/oxygen partial pressure at a room temperature. The plasma dynamics of the process, reactive and sputtered gas particles was investigated via optical emission spectroscopy. We then studied the correlations between the plasma states and the structural/optical properties of the films. The growth rate and morphology of the titanium dioxide thin films turned out to be contingent with the population and the energy profile of Ar, O, and TiO plasma. In particular, the films grown under energetic TiO plasma have shown a direct band-to-band transition with an optical energy band gap up to ∼4.2 eV.

CdO thin films based on the annealing temperature differences prepared by sol-gel method and their heterojunction devices

NASA Astrophysics Data System (ADS)

Soylu, M.; Yazici, T.

2017-12-01

Undoped CdO films were prepared on glass substrate and p-type silicon wafer using sol-gel spin coating method. The structural and optical properties of the films were investigated as a function of the annealing temperature. X-ray diffraction (XRD) patterns reveal that the films are formed from CdO with cubic crystal structure and (1 1 1) preferred orientation. It is seen that good crystallinity is due to the high annealing temperature. The surface morphology of the CdO films was found to be depending on the annealing temperature, showing cauliflower like structure. Optical band gaps for annealing temperature of 250 °C and 450 °C were found to be 2.49 eV and 2.27 eV, respectively, showing a decrease with raising temperature. Optics parameters such as extinction coefficient, refractive index, and surface-volume energy loss were determined with spectrophotometric analysis as a function of annealing temperature. CdO/p-Si heterojunction structure showed weak rectifying behavior. The diode parameters were found to be depending on annealing temperature. The results are encouraging to get better conjunction with CdO thin film component at optimize annealing temperature.

Ultrahigh resolution optical coherence tomography for quantitative topographic mapping of retinal and intraretinal architectural morphology

NASA Astrophysics Data System (ADS)

Ko, Tony H.; Hartl, Ingmar; Drexler, Wolfgang; Ghanta, Ravi K.; Fujimoto, James G.

2002-06-01

Quantitative, three-dimensional mapping of retinal architectural morphology was achieved using an ultrahigh resolution ophthalmic OCT system. This OCT system utilizes a broad bandwidth titanium-sapphire laser light source generating bandwidths of up to 300 nm near 800 nm center wavelength. The system enables real-time cross-sectional imaging of the retina with ~3 micrometers axial resolution. The macula and the papillomacular axis of a normal human subject were systematically mapped using a series of linear scans. Edge detection and segmentation algorithms were developed to quantify retinal and intraretinal thicknesses. Topographic mapping of the total retinal thickness and the total ganglion cell/inner plexiform layer thickness was achieved around the macula. A topographic mapping quantifying the progressive thickening of the nerve fiber layer (NFL) nasally approaching the optic disk was also demonstrated. The ability to create three-dimensional topographic mapping of retinal architectural morphology at ~3 micrometers axial resolution will be relevant for the diagnosis of many retinal diseases. The topographic quantification of these structures can serve as a powerful tool for developing algorithms and clinical scanning protocols for the screening and staging of ophthalmic diseases such as glaucoma.

Aberrant ocular architecture and function in patients with Klinefelter syndrome.

PubMed

Brand, Cristin; Zitzmann, Michael; Eter, Nicole; Kliesch, Sabine; Wistuba, Joachim; Alnawaiseh, Maged; Heiduschka, Peter

2017-10-13

Klinefelter Syndrome (KS), the most common chromosomal disorder in men (47,XXY), is associated with numerous comorbidities. Based on a number of isolated case reports, we performed the first systematic and comprehensive evaluation of eye health in KS patients with a focus on ocular structure and vascularization. Twenty-one KS patients and 26 male and 38 female controls underwent a variety of non-invasive examinations investigating ocular morphology (examination of retinal thickness, optic nerve head, and cornea) and function (visual field testing and quantification of ocular vessel density by optical coherence tomography angiography). In comparison to healthy controls, KS patients exhibited a smaller foveal avascular zone and a decreased retinal thickness due to a drastically thinner outer nuclear layer. The cornea of KS patients showed a decreased peripheral thickness and volume. In perimetry evaluation, KS patients required brighter stimuli and gave more irregular values. KS patients show an ocular phenotype including morphological and functional features, which is very likely caused by the supernumerary X chromosome. Thus, KS should not be limited to infertility, endocrine dysfunction, neurocognitive and psychosocial comorbidities. Defining an aberrant ocular morphology and function, awareness for possible eye problems should be raised.

Role of Crystallization in the Morphology of Polymer: Non-fullerene Acceptor Bulk Heterojunctions

DOE PAGES

O’Hara, Kathryn A.; Ostrowski, David P.; Koldemir, Unsal; ...

2017-05-22

Many high efficiency organic photovoltaics use fullerene-based acceptors despite their high production cost, weak optical absorption in the visible range, and limited synthetic variability of electronic and optical properties. To circumvent this deficiency, non-fullerene small-molecule acceptors have been developed that have good synthetic flexibility, allowing for precise tuning of optoelectronic properties, leading to enhanced absorption of the solar spectrum and increased open-circuit voltages ( V OC). We examined the detailed morphology of bulk heterojunctions of poly(3-hexylthiophene) and the small-molecule acceptor HPI-BT to reveal structural changes that lead to improvements in the fill factor of solar cells upon thermal annealing. Themore » kinetics of the phase transformation process of HPI-BT during thermal annealing were investigated through in situ grazing incidence wide-angle X-ray scattering studies, atomic force microscopy, and transmission electron microscopy. The HPI-BT acceptor crystallizes during film formation to form micron-sized domains embedded within the film center and a donor rich capping layer at the cathode interface reducing efficient charge extraction. Thermal annealing changes the surface composition and improves charge extraction. In conclusion, this study reveals the need for complementary methods to investigate the morphology of BHJs.« less

Role of Crystallization in the Morphology of Polymer: Non-fullerene Acceptor Bulk Heterojunctions

DOE Office of Scientific and Technical Information (OSTI.GOV)

O’Hara, Kathryn A.; Ostrowski, David P.; Koldemir, Unsal

Many high efficiency organic photovoltaics use fullerene-based acceptors despite their high production cost, weak optical absorption in the visible range, and limited synthetic variability of electronic and optical properties. To circumvent this deficiency, non-fullerene small-molecule acceptors have been developed that have good synthetic flexibility, allowing for precise tuning of optoelectronic properties, leading to enhanced absorption of the solar spectrum and increased open-circuit voltages ( V OC). We examined the detailed morphology of bulk heterojunctions of poly(3-hexylthiophene) and the small-molecule acceptor HPI-BT to reveal structural changes that lead to improvements in the fill factor of solar cells upon thermal annealing. Themore » kinetics of the phase transformation process of HPI-BT during thermal annealing were investigated through in situ grazing incidence wide-angle X-ray scattering studies, atomic force microscopy, and transmission electron microscopy. The HPI-BT acceptor crystallizes during film formation to form micron-sized domains embedded within the film center and a donor rich capping layer at the cathode interface reducing efficient charge extraction. Thermal annealing changes the surface composition and improves charge extraction. In conclusion, this study reveals the need for complementary methods to investigate the morphology of BHJs.« less

Synthesis of α-MoO{sub 3} nanoplates using organic aliphatic acids and investigation of sunlight enhanced photodegradation of organic dyes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kumar, V. Vinod; Gayathri, K.; Anthony, Savarimuthu Philip, E-mail: philip@biotech.sastra.edu

Graphical abstract: Thermodynamically stable α-MoO{sub 3} nanoplates and nanorods were synthesized using organic structure controlling agents and demonstrated sun light enhanced photocatalytic degradation of methylene blue (MB) and rhodamine blue (Rh-B) dyes in aqueous solution. - Highlights: • α-MoO{sub 3} hexagonal nanoplates using organic structure controlling agents. • Tunable optical band gap of MoO{sub 3}. • Demonstrated strong sun light mediated enhanced photodegradation of methylene blue and rhodamine blue. • Photodegradation did not use any other external oxidizing agents. - Abstract: Thermodynamically stable α-MoO{sub 3} nanoplates were synthesized using organic aliphatic acids as structure controlling agents and investigated photocatalytic degradationmore » of methylene blue (MB) and rhodamine blue (Rh-B) in presence of sun light. Three different organic aliphatic acids, citric acid (CA), tartaric acid (TA) and ethylene diamine tetra-acetic acid (EDTA), were employed to control morphologies. CA and TA predominantly produced extended hexagonal plates where EDTA gave nanorods as well as nanoplates. PXRD studies confirmed the formation of α-MoO{sub 3} nanoparticles. HR-TEM and FE-SEM reveal the formation of plate morphologies with 20–40 nm thickness, 50–100 nm diameter and 600 nm lengths. The different morphologies of α-MoO{sub 3} nanoparticles lead to the tunable optical band gap between 2.80 and 2.98 eV which was obtained from diffused reflectance spectra (DRS). Interestingly, the synthesized α-MoO{sub 3} nanoplates exhibited strong photocatalytic degradation of MB and Rh-B up to 99% in presence of sun light without using any oxidizing agents.« less

Large-angle illumination STEM: Toward three-dimensional atom-by-atom imaging

DOE PAGES

Ishikawa, Ryo; Lupini, Andrew R.; Hinuma, Yoyo; ...

2014-11-26

To completely understand and control materials and their properties, it is of critical importance to determine their atomic structures in all three dimensions. Recent revolutionary advances in electron optics – the inventions of geometric and chromatic aberration correctors as well as electron source monochromators – have provided fertile ground for performing optical depth sectioning at atomic-scale dimensions. In this study we theoretically demonstrate the imaging of top/sub-surface atomic structures and identify the depth of single dopants, single vacancies and the other point defects within materials by large-angle illumination scanning transmission electron microscopy (LAI-STEM). The proposed method also allows us tomore » measure specimen properties such as thickness or three-dimensional surface morphology using observations from a single crystallographic orientation.« less

Comparative study of Ni and Cu doped ZnO nanoparticles: Structural and optical properties

NASA Astrophysics Data System (ADS)

Thakur, Shaveta; Thakur, Samita; Sharma, Jyoti; Kumar, Sanjay

2018-05-01

Nanoparticles of undoped and doped (0.1 M Ni2+ and Cu2+) ZnO are synthesized using chemical precipitation method. The crystallite size, morphology, chemical bonding and optical properties of as prepared nanoparticles are determined by X-ray diffraction (XRD), Scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy and UV-visible spectra. XRD analysis shows that the prepared samples are single phase and have hexagonal wurtzite structure. The crystallite size of the doped and undoped nanoparticles is determined using Scherrer method. The crystallite size is found to be increased with concentration of nickel and copper. All stretching and vibrational bands are observed at their specific positions through FTIR. The increase in band gap can be attributed to the different chemical nature of dopant and host cation.

Some observations on rutherfordine

USGS Publications Warehouse

Clark, Joan R.; Christ, C.L.

1956-01-01

The optical properties of rutherfordine, UO2CO3, previously determined on microscopic crystals, have been redetermined on considerably larger crystals; and the relations among the indices of refraction, the morphology, and the crystal structure have been examined. Rutherfordine is orthorhombic, biaxial positive, with α = 1.715, β = 1.730, γ = 1.795, 2V = 53° (calc.); X = b, Y = c (elongation, Z = a. The crystal structure of UO2CO 3 consists of layers of carbonate groups parallel to (010) with linear (O-U-O) ions normal to the layers. The indices β and γ correspond to vibration directions parallel to layers; the unexpectedly large difference in value between β and γ is ascribed to the optical anisotropy of the uranium-oxygen bonding in the layer. Indexed X-ray powder data are given.

Structural, optical and photoelectric properties of sprayed CdS thin films

NASA Astrophysics Data System (ADS)

Chandel, Tarun; Dwivedi, Shailendra Kumar; Zaman, M. Burhanuz; Rajaram, P.

2018-05-01

In this study, CdS thin films were grown via a facile spray pyrolysis technique. The crystalline phase, morphological, compositional and optical properties of the CdS thin films have been studied using X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and UV-vis absorption spectroscopy, respectively. XRD patterns show that the grown CdS films crystallized in the hexagonal structure. Scanning electron microscopy (SEM) study shows that the surfaces of the films are smooth and are uniformly covered with nanoparticles. EDAX results reveal that the grown films have good stochiometry. UV-vis spectroscopy shows that the grown films have transparency above 80% over the entire visible region. The photo-electric response of the CdS films grown on glass substrates has been observed.

Effect of 60Co γ-irradiation on structural and optical properties of thin films of Ga10Se80Hg10

NASA Astrophysics Data System (ADS)

Ahmad, Shabir; Asokan, K.; Shahid Khan, Mohd.; Zulfequar, M.

2015-08-01

Thin films of Ga10Se80Hg10 have been deposited onto a chemically cleaned Al2O3 substrates by thermal evaporation technique under vacuum. The investigated thin films are irradiated by 60Co γ-rays in the dose range of 50-150 kGy. X-ray diffraction patterns of the investigated thin films confirm the preferred crystallite growth occurs in the tetragonal phase structure. It also shows, the average crystallite size increases after γ-exposure, which indicates the crystallinity of the material increases after γ-irradiation. These results were further supported by surface morphological analysis carried out by scanning electron microscope and atomic force microscope which also shows the crystallinity of the material increases with increasing the γ-irradiation dose. The optical transmission spectra of the thin films at normal incidence were investigated in the spectral range from 190 to 1100 nm. Using the transmission spectra, the optical constants like refractive index (n) and extinction coefficient (k) were calculated based on Swanepoel's method. The optical band gap (Eg) was also estimated using Tauc's extrapolation procedure. The optical analysis shows: the value of optical band gap of investigated thin films decreases and the corresponding absorption coefficient increases continuously with increasing dose of γ-irradiation.

Quaternary schematics for property engineering of CdSe thin films

NASA Astrophysics Data System (ADS)

Chavan, G. T.; Pawar, S. T.; Prakshale, V. M.; Sikora, A.; Pawar, S. M.; Chaure, N. B.; Kamble, S. S.; Maldar, N. N.; Deshmukh, L. P.

2017-12-01

The synthesis of quaternary Cd1-xZnxSySe1-y (0 ≤ x = y ≤ 0.35) thin films was done through indigenously developed chemical solution growth process. As-obtained thin films were subjected to the physical, chemical, structural and optical characterizations. The nearly hydrophobic nature of the as-deposited films except binary CdSe was observed through the wettability studies. The colorimetric studies supported a change in physical color attributes. The elemental analysis done confirmed the formation of Cd(Zn, S)Se and the chemical states of constituent elements as Cd2+, Zn2+, S2- and Se2-. Structural assessment suggested the formation of the polycrystalline quaternary phase of the hexagonal wurtzite structure. The Raman spectroscopy was also employed for the confirmation studies on Cd1-xZnxSySe1-y thin films. Morphological observations indicated microstructural transformation from an aggregated bunch of nano-sized globular grains into a rhomboid network of petal/flakes like crystallites. The atomic force micrographs (AFM) revealed the enhancement in the hillock structures. From advanced AFM characterizations, we observed that the CdSe thin film has leptokurtic (Sku = 3.23) surface, whereas, quaternary Cd(Zn, S)Se films have platykurtic (Sku < 3) surface. The orientation of the surface morphology was observed through the angular spectrum studies. The optical absorption studies revealed direct allowed transition for the films with a continuous modulation of the energy bandgap from 1.8 eV to 2.31 eV.

Morphology and kinetics of the formation of polyamide benzimidazole in N-methylpyrrolidone

NASA Astrophysics Data System (ADS)

Khanchich, O. A.; Larionov, V. B.; Biryukov, A. L.

2018-02-01

Polymerization-optical methods were used to study the supermolecular structure in the gelation of systems based on polyamidobenzimidazole (PABI) in N-methylpyrrolidone (N-MP) and the kinetics of phase transformations during polymer coagulation from a the solution. It was found that the use of N-MP leads to the appearance in the PABI-N-MP-H2O system of spherulites having a structure characteristic of LC structures. It is shown that the alternation of metastable structures upon gelation of the PABY - N-MP-H2O system is consistent with the appearance of the LC phase of the cholesteric type.

Honeycomb Films with Core-Shell Dispersed Phases Prepared by the Combination of Breath Figures and Phase Separation Process of Ternary Blends.

PubMed

Del Campo, A; de León, A S; Rodríguez-Hernández, J; Muñoz-Bonilla, A

2017-03-21

Herein, we propose a strategy to fabricate core-shell microstructures ordered in hexagonal arrays by combining the breath figures approach and phase separation of immiscible ternary blends. This simple strategy to fabricate these structures involves only the solvent casting of a ternary polymer blend under moist atmosphere, which provides a facile and low-cost fabrication method to obtain the porous structures with a core-shell morphology. For this purpose, blends consisting of polystyrene (PS) as a major component and PS 40 -b-P(PEGMA300) 48 amphiphilic copolymer and polydimethylsiloxane (PDMS) as minor components were dissolved in tetrahydrofuran and cast onto glass wafers under humid conditions, 70% of relative humidity. The resulting porous morphologies were characterized by optical and confocal Raman microscopy. In particular, confocal Raman results demonstrated the formation of core-shell morphologies into the ordered pores, in which the PS forms the continuous matrix, whereas the other two phases are located into the cavities (PDMS is the core while the amphiphilic copolymer is the shell). Besides, by controlling the weight ratio of the polymer blends, the structural parameters of the porous structure such as pore diameter and the size of the core can be effectively tuned.

Temperature-Driven Structural and Morphological Evolution of Zinc Oxide Nano-Coalesced Microstructures and Its Defect-Related Photoluminescence Properties

PubMed Central

Lim, Karkeng; Abdul Hamid, Muhammad Azmi; Shamsudin, Roslinda; Al-Hardan, N.H.; Mansor, Ishak; Chiu, Weesiong

2016-01-01

In this paper, we address the synthesis of nano-coalesced microstructured zinc oxide thin films via a simple thermal evaporation process. The role of synthesis temperature on the structural, morphological, and optical properties of the prepared zinc oxide samples was deeply investigated. The obtained photoluminescence and X-ray photoelectron spectroscopy outcomes will be used to discuss the surface structure defects of the prepared samples. The results indicated that the prepared samples are polycrystalline in nature, and the sample prepared at 700 °C revealed a tremendously c-axis oriented zinc oxide. The temperature-driven morphological evolution of the zinc oxide nano-coalesced microstructures was perceived, resulting in transformation of quasi-mountain chain-like to pyramidal textured zinc oxide with increasing the synthesis temperature. The results also impart that the sample prepared at 500 °C shows a higher percentage of the zinc interstitial and oxygen vacancies. Furthermore, the intensity of the photoluminescence emission in the ultraviolet region was enhanced as the heating temperature increased from 500 °C to 700 °C. Lastly, the growth mechanism of the zinc oxide nano-coalesced microstructures is discussed according to the reaction conditions. PMID:28773425

Modification of the morphology and optical properties of SnS films using glancing angle deposition technique

NASA Astrophysics Data System (ADS)

Sazideh, M. R.; Dizaji, H. Rezagholipour; Ehsani, M. H.; Moghadam, R. Zarei

2017-05-01

Tin sulfide (SnS) films were prepared by thermal evaporation method using Glancing Angle Deposition (GLAD) technique at zero and different oblique incident flux angles (α = 45°, 55°, 65°, 75° and 85°). The physical properties of prepared films were systematically investigated. The X-ray diffraction analysis indicated that the film deposited at α = 0° formed as single phase with an orthorhombic structure. However, the layers became amorphous at α = 45°, 55°, 65°, 75° and 85°. Beside the appearance of amorphous feature in the film prepared at α higher than zero, Sn2S3 phase was also observed. The top and cross-sectional field emission scanning electron microscope (FESEM) images of the samples showed noticeable changes in the structure and morphology of individual nano-plates as a function of incident angle. The band gap and refractive index values of the films were calculated by optical transmission measurements. The optical band-gap values were observed to increase with increasing the incident flux angle. This can be due to presence of Sn2S3 phase observed in the samples produced at α values other than zero. The effective refractive index and porosity exhibit an opposite evolution as the incident angle α rises. At α = 85° the layers show a considerable change in effective refractive index (Δn = 1.7) at near-IR spectral range.

An investigation of the Nb doping effect on structural, morphological, electrical and optical properties of spray deposited F doped SnO2 films

NASA Astrophysics Data System (ADS)

Turgut, G.; Keskenler, E. F.; Aydın, S.; Yılmaz, M.; Doǧan, S.; Düzgün, B.

2013-03-01

F and Nb + F co-doped SnO2 thin films were deposited on glass substrates by the spray pyrolysis method. The microstructural, morphological, electrical and optical properties of the 10 wt% F doped SnO2 (FTO) thin films were investigated specifically for niobium (Nb) doping in the range of 0-4 at.% with 1 at.% steps. As shown by the x-ray diffraction patterns, the films exhibited a tetragonal cassiterite structure with (200) preferential orientation. It was observed that grain sizes of the films for (200) and (301) peaks depended on the Nb doping concentration and varied in the range of 25.11-32.19 and 100.6-183.7 nm, respectively. The scanning electron microscope (SEM) micrographs showed that the FTO films were made of small pyramidal grains, while doubly doped films were made of small pyramidal grains and big polyhedron grains. From electrical studies, although 1 at.% Nb doped FTO films have the lowest sheet resistance and resistivity values, the highest figure-of-merit and optical band gap values obtained for FTO films were 16.2 × 10-2 Ω-1 and 4.21 eV, respectively. Also, infrared reflectivity values of the films were in the range of 97.39-98.98%. These results strongly suggest that these films are an attractive candidate for various optoelectronic applications and for photothermal conversion of solar energy.

Characterization of dynamic physiology of the bladder by optical coherence tomography

NASA Astrophysics Data System (ADS)

Yuan, Zhijia; Keng, Kerri; Pan, Rubin; Ren, Hugang; Du, Congwu; Kim, Jason; Pan, Yingtian

2012-03-01

Because of its high spatial resolution and noninvasive imaging capabilities, optical coherence tomography has been used to characterize the morphological details of various biological tissues including urinary bladder and to diagnose their alternations (e.g., cancers). In addition to static morphology, the dynamic features of tissue morphology can provide important information that can be used to diagnose the physiological and functional characteristics of biological tissues. Here, we present the imaging studies based on optical coherence tomography to characterize motion related physiology and functions of rat bladder detrusor muscles and compared the results with traditional biomechanical measurements. Our results suggest that optical coherence tomography is capable of providing quantitative evaluation of contractile functions of intact bladder (without removing bladder epithelium and connective tissue), which is potentially of more clinical relevance for future clinical diagnosis - if incorporated with cystoscopic optical coherence tomography.

COMPARATIVE STUDY OF ASYMMETRY ORIGIN OF GALAXIES IN DIFFERENT ENVIRONMENTS. I. OPTICAL OBSERVATIONS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Plauchu-Frayn, I.; Coziol, R., E-mail: plauchuf@astro.ugto.m, E-mail: rcoziol@astro.ugto.m

2010-06-15

This paper presents the first of two analyses about the influence of environment on the formation and evolution of galaxies observed in the nearby universe. For our study, we used three different samples representing different density environments: galaxies in Compact Groups (HCGs), Isolated Pairs of Galaxies (KPGs), and Isolated Galaxies (KIGs), which were taken as references. Usingboth characteristic isophotal parameters and evidence of asymmetries in the optical and the near-infrared, we are able to establish differences in the characteristics of galaxies with different morphologies in different environments, allowing us to better understand their different formation histories. In this first paper,more » we present the isophotal and asymmetry analyses of a sample of 214 galaxies in different environments observed in the optical (V and I images). For each galaxy, we have determined different characteristic isophotal parameters and V - I color profiles, as a function of semi-major axis, and performed a full asymmetry analysis in residual images using the V filter. Evidence of asymmetry in the optical is almost missing in the KIG sample and significantly more common in the KPG than in the HCG samples. Our isophotal analysis suggests that the stellar populations in the HCG galaxies are older and more dynamically relaxed than in the KPG. The HCG galaxies seem to be at a more advanced stage of interaction than the KPGs. One possible explanation is that these structures formed at different epochs: compact groups of galaxies would have formed before close pairs of galaxies, which only began interacting recently. However, similarities in the formation process of galaxies with same morphology suggest CGs and close pairs of galaxies share similar conditions; they are new structures forming relatively late in low-density environments.« less

The 27-28 October 1986 FIRE IFO Cirrus Case Study: Cloud Optical Properties Determined by High Spectral Resolution Lidar

NASA Technical Reports Server (NTRS)

Grund, C. J.; Eloranta, E. W.

1996-01-01

During the First ISCCP Region Experiment (FIRE) cirrus intensive field observation (IFO) the High Spectral Resolution Lidar was operated from a roof top site on the University of Wisconsin-Madison campus. Because the HSRL technique separately measures the molecular and cloud particle backscatter components of the lidar return, the optical thickness is determined independent of particle backscatter. This is accomplished by comparing the known molecular density distribution to the observed decrease in molecular backscatter signal with altitude. The particle to molecular backscatter ratio yields calibrated measurements of backscatter cross sections that can be plotted ro reveal cloud morphology without distortion due to attenuation. Changes in cloud particle size, shape, and phase affect the backscatter to extinction ratio (backscatter-phase function). The HSRL independently measures cloud particle backscatter phase function. This paper presents a quantitative analysis of the HSRL cirrus cloud data acquired over an approximate 33 hour period of continuous near zenith observations. Correlations between small scale wind structure and cirrus cloud morphology have been observed. These correlations can bias the range averaging inherent in wind profiling lidars of modest vertical resolution, leading to increased measurement errors at cirrus altitudes. Extended periods of low intensity backscatter were noted between more strongly organized cirrus cloud activity. Optical thicknesses ranging from 0.01-1.4, backscatter phase functions between 0.02-0.065 sr (exp -1) and backscatter cross sections spanning 4 orders of magnitude were observed. the altitude relationship between cloud top and bottom boundaries and the cloud optical center altitude was dependent on the type of formation observed Cirrus features were observed with characteristic wind drift estimated horizontal sizes of 5-400 km. The clouds frequently exhibited cellular structure with vertical to horizontal dimension ratios of 1:5-1:1.

Role of Silver Salts Lattice Energy on Conductivity Drops in Chitosan Based Solid Electrolyte: Structural, Morphological and Electrical Characteristics

NASA Astrophysics Data System (ADS)

Aziz, Shujahadeen B.; Abdullah, Omed Gh.; Hussein, Sarkawt A.

2018-03-01

The influence of anion type on silver ion reduction and drop in direct current (DC) conductivity was investigated experimentally. The structural, optical, morphological and electrical properties of the samples were investigated using x-ray diffraction (XRD), ultraviolet-visible (UV-Vis), optical micrographs (OM) and impedance spectroscopy. The XRD results reveal significant disruption in the crystalline structure of chitosan (CS) for different concentrations of silver nitrate (AgNt) salt. The localized surface resonance plasmonic (LSRP) peaks that were observed for CS:AgNt samples, along with the white silver specs detected by OM technique confirm the formation of Ag nanoparticles. The appearance of obvious dark regions in the CS:AgNt system reveals the existence of a large percentage of amorphous domains. The nonexistence of spherulitic texture confirms the amorphous nature of the samples. The second semicircle in an impedance plot can be attributed to an Ag nanoparticle grain boundary. The established relationships between dielectric constant and carrier concentration and the behavior of dielectric constant versus salt concentration were used to explain the phenomenon of ion-ion association. The continuous increase of DC conductivity was noticed at high temperatures, which was then explained on the basis of lattice energy of silver salts. The influences of anion size on the rate of silver ion reductions are also interpreted.

WISE J233237.05-505643.5: A Double-Peaked Broad-Lined AGN with Spiral-Shaped Radio Morphology

NASA Technical Reports Server (NTRS)

Tsai, Chao Wei; Jarrett, Thomas H.; Stern, Daniel; Emonts, Bjorn; Barrows, R. Scott; Assef, Roberto J.; Norris, Ray P.; Eisenhardt, Peter R. M.; Lonsdale, Carol; Blain, Andrew W.;

The Evolution and Structure of Extreme Optical Lightning Flashes.

PubMed

Peterson, Michael; Rudlosky, Scott; Deierling, Wiebke

2017-12-27

This study documents the composition, morphology, and motion of extreme optical lightning flashes observed by the Lightning Imaging Sensor (LIS). The furthest separation of LIS events (groups) in any flash is 135 km (89 km), the flash with the largest footprint had an illuminated area of 10,604 km 2 , and the most dendritic flash has 234 visible branches. The longest-duration convective LIS flash lasted 28 s and is overgrouped and not physical. The longest-duration convective-to-stratiform propagating flash lasted 7.4 s, while the longest-duration entirely stratiform flash lasted 4.3 s. The longest series of nearly consecutive groups in time lasted 242 ms. The most radiant recorded LIS group (i.e., "superbolt") is 735 times more radiant than the average group. Factors that impact these optical measures of flash morphology and evolution are discussed. While it is apparent that LIS can record the horizontal development of the lightning channel in some cases, radiative transfer within the cloud limits the flash extent and level of detail measured from orbit. These analyses nonetheless suggest that lightning imagers such as LIS and Geostationary Lightning Mapper can complement ground-based lightning locating systems for studying physical lightning phenomena across large geospatial domains.

Hybrid nanostructures of metal/two-dimensional nanomaterials for plasmon-enhanced applications.

PubMed

Li, Xuanhua; Zhu, Jinmeng; Wei, Bingqing

2016-06-07

Hybrid nanostructures composed of graphene or other two-dimensional (2D) nanomaterials and plasmonic metal components have been extensively studied. The unusual properties of 2D materials are associated with their atomically thin thickness and 2D morphology, and many impressive structures enable the metal nanomaterials to establish various interesting hybrid nanostructures with outstanding plasmonic properties. In addition, the hybrid nanostructures display unique optical characteristics that are derived from the close conjunction of plasmonic optical effects and the unique physicochemical properties of 2D materials. More importantly, the hybrid nanostructures show several plasmonic electrical effects including an improved photogeneration rate, efficient carrier transfer, and a plasmon-induced "hot carrier", playing a significant role in enhancing device performance. They have been widely studied for plasmon-enhanced optical signals, photocatalysis, photodetectors (PDs), and solar cells. In this review, the developments in the field of metal/2D hybrid nanostructures are comprehensively described. Preparation of hybrid nanostructures is first presented according to the 2D material type, as well as the metal nanomaterial morphology. The plasmonic properties and the enabled applications of the hybrid nanostructures are then described. Lastly, possible future research in this promising field is discussed.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Atanasov, Petar A., E-mail: paatanas@ie.bas.bg; Nedyalkov, Nikolay N.; Valova, Eugenia I.

We present an experimental analysis on surface structuring of polydimethylsiloxane films with UV (263 nm) femtosecond laser pulses, in air. Laser processed areas are analyzed by optical microscopy, SEM, and μ-Raman spectroscopy. The laser-treated sample shows the formation of a randomly nanostructured surface morphology. μ-Raman spectra, carried out at both 514 and 785 nm excitation wavelengths, prior and after laser treatment allow evidencing the changes in the sample structure. The influence of the laser fluence on the surface morphology is studied. Finally, successful electro-less metallization of the laser-processed sample is achieved, even after several months from the laser-treatment contrary to previous observationmore » with nanosecond pulses. Our findings address the effectiveness of fs-laser treatment and chemical metallization of polydimethylsiloxane films with perspective technological interest in micro-fabrication devices for MEMS and nano-electromechanical systems.« less

Role of Cu in engineering the optical properties of SnO2 nanostructures: Structural, morphological and spectroscopic studies

NASA Astrophysics Data System (ADS)

Kumar, Virender; Singh, Kulwinder; Jain, Megha; Manju; Kumar, Akshay; Sharma, Jeewan; Vij, Ankush; Thakur, Anup

2018-06-01

We have carried out a systematic study to investigate the effect of Cu doping on the optical properties of SnO2 nanostructures synthesized by chemical route. Synthesized nanostructures were characterized using X-ray diffraction (XRD), Field emission scanning electron microscopy (FE-SEM), High resolution transmission electron microscopy (HR-TEM), Energy dispersive X-ray spectroscopy, Raman spectroscopy, Fourier transform infrared (FTIR) spectroscopy, UV-visible and Photoluminescence (PL) spectroscopy. The Rietveld refinement analysis of XRD patterns of Cu-doped SnO2 samples confirmed the formation of single phase tetragonal rutile structure, however some localized distortion was observed for 5 mol% Cu-doped SnO2. Crystallite size was found to decrease with increase in dopant concentration. FE-SEM images indicated change in morphology of samples with doping. HR-TEM images revealed that synthesized nanostructures were nearly spherical and average crystallite size was in the range 12-21 nm. Structural defects, crystallinity and size effects on doping were investigated by Raman spectroscopy and results were complemented by FTIR spectroscopy. Optical band gap of samples was estimated from reflectance spectra. We have shown that band gap of SnO2 can be engineered from 3.62 to 3.82 eV by Cu doping. PL emission intensity increased as the doping concentration increased, which can be attributed to the development of defect states in the forbidden transition region of band gap of SnO2 with doping. We have also proposed a band model owing to defect states in SnO2 to explain the observed PL in Cu doped SnO2 nanostructures.

The role of Tin Oxide Concentration on The X-ray Diffraction, Morphology and Optical Properties of In2O3:SnO2 Thin Films

NASA Astrophysics Data System (ADS)

Hasan, Bushra A.; Abdallah, Rusul M.

2018-05-01

Alloys were performed from In2O3 doped SnO2 with different doping ratio by quenching from the melt technique. Pulsed Laser Deposition PLD was used to deposit thin films of different doping ratio In2O3 : SnO2 (0, 1, 3, 5, 7 and 9 % wt.) on glass substrate at ambient temperature under vacuum of 10-3 bar thickness of ∼100nm. The structural type,grain size and morphology of the prepared alloys compounds and thin films were examined using X-ray diffraction and atomic force microscopy. The results showed that all alloys have polycrystalline structures and the peaks belonged to the preferred plane for crystal growth were identical with the ITO (Indium – Tin –Oxide) standard cards also another peaks were observed belonged to SnO2 phase. The structures of thin films was also polycrystalline, and the predominate peaks are identical with standard cards ITO. On the other side the prepared thin films declared decrease a reduction of degree of crystallinity with the increase of doping ratio. Atomic Force Microscopy AFM measurements showed the average grain size and average surface roughness exhibit to change in systematic manner with the increase of doping ratio with tin oxide. The optical measurements show that the In2O3:SnO2 thin films have a direct energy gap Eg opt in the first stage decreases with the increase of doping ratio and then get to increase with further increase of doping ration, whereas reverse to that the optical constants such as refractive index (n), extinction coefficient (k) and dielectric constant (εr, εi) have a regular increase with the doping ratio by tin oxide and then decreases.

Extreme Light Management in Mesoporous Wood Cellulose Paper for Optoelectronics.

PubMed

Zhu, Hongli; Fang, Zhiqiang; Wang, Zhu; Dai, Jiaqi; Yao, Yonggang; Shen, Fei; Preston, Colin; Wu, Wenxin; Peng, Peng; Jang, Nathaniel; Yu, Qingkai; Yu, Zongfu; Hu, Liangbing

2016-01-26

Wood fibers possess natural unique hierarchical and mesoporous structures that enable a variety of new applications beyond their traditional use. We dramatically modulate the propagation of light through random network of wood fibers. A highly transparent and clear paper with transmittance >90% and haze <1.0% applicable for high-definition displays is achieved. By altering the morphology of the same wood fibers that form the paper, highly transparent and hazy paper targeted for other applications such as solar cell and antiglare coating with transmittance >90% and haze >90% is also achieved. A thorough investigation of the relation between the mesoporous structure and the optical properties in transparent paper was conducted, including full-spectrum optical simulations. We demonstrate commercially competitive multitouch touch screen with clear paper as a replacement for plastic substrates, which shows excellent process compatibility and comparable device performance for commercial applications. Transparent cellulose paper with tunable optical properties is an emerging photonic material that will realize a range of much improved flexible electronics, photonics, and optoelectronics.

Crystal growth, spectral, structural and optical studies of π-conjugated stilbazolium crystal: 4-bromobenzaldehyde-4'-N'-methylstilbazolium tosylate.

PubMed

Krishna Kumar, M; Sudhahar, S; Bhagavannarayana, G; Mohan Kumar, R

2014-05-05

Nonlinear optical (NLO) organic compound, 4-bromobenzaldehyde-4'-N'-methylstilbazolium tosylate was synthesized by reflux method. The formation of molecular complex was confirmed from (1)H NMR, FT-IR and FT-Raman spectral analyses. The single crystals were grown by slow evaporation solution growth method and the crystal structure and atomic packing of grown crystal was identified. The morphology and growth axis of grown crystal were determined. The crystal perfection was analyzed using high resolution X-ray diffraction study on (001) plane. Thermal stability, decomposition stages and melting point of the grown crystal were analyzed. The optical absorption coefficient (α) and energy band gap (E(g)) of the crystal were determined using UV-visible absorption studies. Second harmonic generation efficiency of the grown crystal was examined by Kurtz powder method with different particle size using 1064 nm laser. Laser induced damage threshold study was carried out for the grown crystal using Nd:YAG laser. Copyright © 2014 Elsevier B.V. All rights reserved.

Influence of Heat Treatment Conditions on the Properties of Vanadium Oxide Thin Films for Thermochromic Applications.

PubMed

Kim, Donguk; Kwon, Samyoung; Park, Young; Boo, Jin-Hyo; Nam, Sang-Hun; Joo, Yang Tae; Kim, Minha; Lee, Jaehyeong

2016-05-01

In present work, the effects of the heat treatment on the structural, optical, and thermochromic properties of vanadium oxide films were investigated. Vanadium dioxide (VO2) thin films were deposited on glass substrate by reactive pulsed DC magnetron sputtering from a vanadium metal target in mixture atmosphere of argon and oxygen gas. Various heat treatment conditions were applied in order to evaluate their influence on the crystal phases formed, surface morphology, and optical properties. The films were characterized by an X-ray diffraction (XRD) in order to investigate the crystal structure and identify the phase change as post-annealing temperature of 500-600 degrees C for 5 minutes. Surface conditions of the obtained VO2(M) films were analyzed by field emission scanning electron microscopy (FE-SEM) and the semiconductor-metal transition (SMT) characteristics of the VO2 films were evaluate by optical spectrophotometry in the UV-VIS-NIR, controlling temperature of the films.

HIGH-k GATE DIELECTRIC: AMORPHOUS Ta/La2O3 FILMS GROWN ON Si AT LOW PRESSURE

NASA Astrophysics Data System (ADS)

Bahari, Ali; Khorshidi, Zahra

2014-09-01

In the present study, Ta/La2O3 films (La2O3 doped with Ta2O5) as a gate dielectric were prepared using a sol-gel method at low pressure. Ta/La2O3 film has some hopeful properties as a gate dielectric of logic device. The structure and morphology of Ta/La2O3 films were studied using X-ray diffraction (XRD), atomic force microscopy (AFM) and scanning electron microscopy (SEM). Electrical properties of films were performed using capacitance-voltage (C-V) and current density-voltage (J-V) measurements. The optical bandgap of samples was studied by UV-visible optical absorbance measurement. The optical bandgap, Eopt, is determined from the absorbance spectra. The obtained results show that Ta/La2O3 film as a good gate dielectric has amorphous structure, good thermal stability, high dielectric constant (≈ 25), low leakage current and wide bandgap (≈ 4.7 eV).

Effect of replacing Sn4+ ions by Zn2+ ions on structural, optical and magnetic properties of SnO2 nanoparticles

NASA Astrophysics Data System (ADS)

Selvi, E. Thamarai; Sundar, S. Meenakshi

2017-05-01

This paper highlights on the consequence of replacing tetravalent Sn4+ ions of the SnO2 by divalent Zn2+ ions on their structural, optical, and magnetic properties. Samples of Sn1- x Zn x O2 with x = 0, 0.01, 0.02, 0.03, and 0.04 were synthesized using microwave irradiated solvothermal process. The X-ray powder diffraction patterns reveal the rutile tetragonal phase of all doped SnO2 samples with no secondary phases. The transmission electron microscopy results show the formation of spherical nanoparticles of size 10-30 nm. Morphological changes were observed by scanning electron microscopy. The functional groups were investigated using Fourier transform infrared spectroscopy studies. Optical studies were carried by UV-Vis spectroscopy and fluorescence spectroscopy. Electron paramagnetic resonance was used to calculate the Lande splitting factor ` g'. The magnetic properties using vibrating sample magnetometer exhibit room temperature ferromagnetism for all the samples.

Isotope effect in heavy/light water suspensions of optically active gold nanoparticles

NASA Astrophysics Data System (ADS)

Kutsenko, V. Y.; Artykulnyi, O. P.; Petrenko, V. I.; Avdeev, M. V.; Marchenko, O. A.; Bulavin, L. A.; Snegir, S. V.

2018-04-01

Aqueous suspensions of optically active gold nanoparticles coated with trisodium citrate were synthesized in light (H2O) water and mixture of light and heavy (H2O/D2O) water using the modified Turkevich protocol. The objective of the paper was to verify sensitivity of neutron scattering methods (in particular, neutron reflectometry) to the potential isotope H/D substitution in the stabilizing organic shell around particles in colloidal solutions. First, the isotope effect was studied with respect to the changes in the structural properties of metal particles (size, shape, crystalline morphology) in solutions by electron microscopy including high-resolution transmission electron microscopy from dried systems. The structural factors determining the variation in the adsorption spectra in addition to the change in the optical properties of surrounding medium were discussed. Then, neutron reflectometry was applied to the layered nanoparticles anchored on a silicon wafer via 3-aminopropyltriethoxysilane molecules to reveal the presence of deuterated water molecules in the shell presumably formed by citrate molecules around the metallic core.

Biocomposite Plasma-Sprayed Coatings Based on Zinc-Substituted Hydroxyapatite: Structure, Properties, and Prospects of Application

NASA Astrophysics Data System (ADS)

Lyasnikova, A. V.; Markelova, O. A.; Lyasnikov, V. N.; Dudareva, O. A.

2016-01-01

The method of synthesis of a zinc-substituted hydroxyapatite powder is presented, and the technology of creating coatings by its spraying is described. The results of studies on the morphological, physical, and chemical parameters of a zinc-substituted hydroxyapatite coating by using X-ray analysis, infrared spectroscopy, transmission electron microscopy, optical microscopy, SEM, and other methods are given.

Experimental and theoretical XANES of CdSxSe1-x nanostructures

NASA Astrophysics Data System (ADS)

Yiu, Y. M.; Murphy, M. W.; Liu, L.; Hu, Y.; Sham, T. K.

2014-03-01

The morphology and electronic properties of the CdSxSe1-x nanostructures with varying alloy compositions have been acquired experimentally by X-ray Absorption Near-Edge Structures (XANES) at the Cd, Se and S K-edge and L3,2-edges. The theoretical XANES spectra have been calculated using the density functional approach. It is found that the optical band-gap emission of these CdSxSe1-x nano-ribbons can be tuned to the range between that of pure CdS (2.43 eV) and CdSe (1.74 eV) by changing the S and Se ratio. This gradual shift in (optical and structural) properties from CdS character to CdSe character is also seen in the electronic structures. The densities of states and band structures show that with the addition of Se replacing S in CdS, the band gap shrinks. The K and L3,2 edges of Cd, Se, and S of the XANES structures of both the CdS and CdSe in B4 (wurtzite) and B3 (cubic zinc-blende) structures have been calculated and compared.

Slip-additive migration, surface morphology, and performance on injection moulded high-density polyethylene closures.

PubMed

Dulal, Nabeen; Shanks, Robert; Gengenbach, Thomas; Gill, Harsharn; Chalmers, David; Adhikari, Benu; Pardo Martinez, Isaac

2017-11-01

The amount and distribution of slip agents, erucamide, and behenamide, on the surface of high-density polyethene, is determined by integral characteristics of slip agent structure and polymer morphology. A suite of surface analysis techniques was applied to correlate physicochemical properties with slip-additive migration behaviour and their surface morphology. The migration, surface morphology and physicochemical properties of the slip additives, crystallinity and orientation of polyethene spherulites and interaction between slip additives and high-density polyethene influence the surface characteristics. The high-density polyethene closures were produced with erucamide and behenamide separately and stored until they produced required torque. Surface composition was determined employing spectroscopy and gas chromatography. The distribution of additives was observed under optical, scanning electron and atomic force microscopes. The surface energy, crystallinity and application torque were measured using contact angle, differential scanning calorimeter and a torque force tester respectively. Each slip additive produced a characteristic amide peak at 1645cm -1 in infrared spectroscopy and peaks of oxygen and nitrogen in X-ray photoelectron spectroscopy, suggesting their presence on the surface. The erucamide produced placoid scale-like structures and behenamide formed denticulate structures. The surface erucamide and behenamide responsible for reducing the torque was found to be 15.7µg/cm 2 and 1.7µg/cm 2 . Copyright © 2017 Elsevier Inc. All rights reserved.

Whole blood clot optical clearing for nondestructive 3D imaging and quantitative analysis

PubMed Central

Höök, Peter; Brito-Robinson, Teresa; Kim, Oleg; Narciso, Cody; Goodson, Holly V.; Weisel, John W.; Alber, Mark S.; Zartman, Jeremiah J.

2017-01-01

A technological revolution in both light and electron microscopy imaging now allows unprecedented views of clotting, especially in animal models of hemostasis and thrombosis. However, our understanding of three-dimensional high-resolution clot structure remains incomplete since most of our recent knowledge has come from studies of relatively small clots or thrombi, due to the optical impenetrability of clots beyond a few cell layers in depth. Here, we developed an optimized optical clearing method termed cCLOT that renders large whole blood clots transparent and allows confocal imaging as deep as one millimeter inside the clot. We have tested this method by investigating the 3D structure of clots made from reconstituted pre-labeled blood components yielding new information about the effects of clot contraction on erythrocytes. Although it has been shown recently that erythrocytes are compressed to form polyhedrocytes during clot contraction, observations of this phenomenon have been impeded by the inability to easily image inside clots. As an efficient and non-destructive method, cCLOT represents a powerful research tool in studying blood clot structure and mechanisms controlling clot morphology. Additionally, cCLOT optical clearing has the potential to facilitate imaging of ex vivo clots and thrombi derived from healthy or pathological conditions. PMID:28856043

Structural characterisation of advanced optical materials

NASA Astrophysics Data System (ADS)

Krsmanovic, Radenka

The rare earth systems discussed in this thesis belong to a class of new, advanced optical materials. Two different nanostuctured materials are studied: nanocrystalline oxide phosphors and glass ceramics containing luminescent nanocrystals. In both cases, the optical activity is based on the luminescence properties of rare earth dopants incorporated into the crystal structure of the insulator nanocrystals themselves. The structure, morphology and composition of these luminescent composite materials are investigated and used to demonstrate the benefits as well as the drawbacks of the synthesis and the processing techniques used, aiming to their improvement for possible industrial production. An investigation of the microstructure was done by XRD, TEM and HREM, while EDX, EELS and EFTEM spectroscopy techniques were used for the chemical identification. Our research clearly demonstrated that these techniques can be successfully applied, and in combination with optical spectroscopy can provide the complete characterization of nanostructured luminescent materials. Three different oxide phosphors in the form of nanocrystalline powders are obtained with the solution combustion technique: yttrium aluminum garnet (YAG), gadolinium gallium garnet (GGG) and scandium oxide, Sc2O 3. We found out that GGG and Sc2O3 samples have "perfect" nanocrystals, without defects or amorphous surface layer, and with uniform distribution of rare earth activators. Good crystal quality results in a long-lived phosphor and much stronger emission, which makes them promising candidate for display industry. Moreover, these luminescent nanocrystals are biocompatible and when functionalized with some molecules or biocompatible polymers can be used for bio-applications like "in vivo" markers in cell biology. For luminescence glass ceramics samples the ternary glass system Li 2O-Al2O3-SiO2 (LAS) is used as host matrix, and ZrO2 as nucleating agent for luminescent ions introduced as Eu2O3 or Er2O3. We wanted to obtain a composite with crystal-like optical properties, keeping the transparency and the processibility of the glass host. The spatial distribution of the precipitates throughout the material, their morphology, structure and composition are investigated with various TEM modes to check if we succeed in draining all rare earth dopant ions from the matrix into ZrO2 crystals. The best results are obtained for the samples containing Er as dopant.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hou, Kun; Gao, Ziwei, E-mail: zwgao@snnu.edu.cn; Da, Min

Highlights: Black-Right-Pointing-Pointer Highly oriented and well-defined ZnO urchin-like crystals were successfully fabricated by a facile and effective hydrotherm method. Black-Right-Pointing-Pointer Polyvinylpyrrolidone- and hydrogen peroxide-assisted synthesis of ZnO could optimize its crystalline quality and the obtained ZnO have smooth surface, radial growth of morphology, obvious crystal edges and decreased defects. Black-Right-Pointing-Pointer The physicochemical properties of samples were studied by analysis of its structure, morphology, surface and optical properties. Black-Right-Pointing-Pointer This study represented a multistep mechanism based on [Zn(OH){sub 4}]{sup 2-} growth units about formation such urchin-like structure. -- Abstract: The urchin-like ZnO microcrystals with high crystallinity decomposed from [Zn(OH){sub 4}]{sup 2-}more » directly were obtained via a hydrothermal method. The morphology, particle size, crystalline structure and fluorescence of the as-prepared ZnO were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and photoluminescence (PL) analyses. The results demonstrated that the urchin-like ZnO crystals with wurtzite structure had a narrow distribution in size, which could be adjusted in the range of 30-80 {mu}m by varying reaction time. Broad visible light emission peak was also observed in the PL spectra of the synthesized ZnO products. A multistep growth process about how to form such a structure was proposed.« less

Hybrid single-source online Fourier transform coherent anti-Stokes Raman scattering/optical coherence tomography.

PubMed

Kamali, Tschackad; Považay, Boris; Kumar, Sunil; Silberberg, Yaron; Hermann, Boris; Werkmeister, René; Drexler, Wolfgang; Unterhuber, Angelika

2014-10-01

We demonstrate a multimodal optical coherence tomography (OCT) and online Fourier transform coherent anti-Stokes Raman scattering (FTCARS) platform using a single sub-12 femtosecond (fs) Ti:sapphire laser enabling simultaneous extraction of structural and chemical ("morphomolecular") information of biological samples. Spectral domain OCT prescreens the specimen providing a fast ultrahigh (4×12  μm axial and transverse) resolution wide field morphologic overview. Additional complementary intrinsic molecular information is obtained by zooming into regions of interest for fast label-free chemical mapping with online FTCARS spectroscopy. Background-free CARS is based on a Michelson interferometer in combination with a highly linear piezo stage, which allows for quick point-to-point extraction of CARS spectra in the fingerprint region in less than 125 ms with a resolution better than 4  cm(-1) without the need for averaging. OCT morphology and CARS spectral maps indicating phosphate and carbonate bond vibrations from human bone samples are extracted to demonstrate the performance of this hybrid imaging platform.

Morphology-Controlled Synthesis and Metalation of Porphyrin Nanoparticles with Enhanced Photocatalytic Performance

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Jiefei; Zhong, Yong; Wang, Liang

The design and engineering of the size, shape, and chemistry of photoactive building blocks enables the fabrication of functional nanoparticles for applications in light harvesting, photocatalytic synthesis, water splitting, phototherapy, and photodegradation. Here, we report the synthesis of such nanoparticles through a surfactant-assisted interfacial self-assembly process using optically active porphyrin as a functional building block. The self-assembly process relies on specific interactions such as π–π stacking and metalation (metal atoms and ligand coordination) between individual porphyrin building blocks. Depending on the kinetic conditions and type of surfactants, resulting structures exhibit well-defined one- to three-dimensional morphologies such as nanowires, nanooctahedra, andmore » hierarchically ordered internal architectures. Specifically, electron microscopy and X-ray diffraction results indicate that these nanoparticles exhibit stable single-crystalline and nanoporous frameworks. In conclusion, due to the hierarchical ordering of the porphyrins, the nanoparticles exhibit collective optical properties resulted from coupling of molecular porphyrins and photocatalytic activities such as photodegradation of methyl orange (MO) pollutants and hydrogen production.« less

Morphology-Controlled Synthesis and Metalation of Porphyrin Nanoparticles with Enhanced Photocatalytic Performance

DOE PAGES

Wang, Jiefei; Zhong, Yong; Wang, Liang; ...

2016-09-12

The design and engineering of the size, shape, and chemistry of photoactive building blocks enables the fabrication of functional nanoparticles for applications in light harvesting, photocatalytic synthesis, water splitting, phototherapy, and photodegradation. Here, we report the synthesis of such nanoparticles through a surfactant-assisted interfacial self-assembly process using optically active porphyrin as a functional building block. The self-assembly process relies on specific interactions such as π–π stacking and metalation (metal atoms and ligand coordination) between individual porphyrin building blocks. Depending on the kinetic conditions and type of surfactants, resulting structures exhibit well-defined one- to three-dimensional morphologies such as nanowires, nanooctahedra, andmore » hierarchically ordered internal architectures. Specifically, electron microscopy and X-ray diffraction results indicate that these nanoparticles exhibit stable single-crystalline and nanoporous frameworks. In conclusion, due to the hierarchical ordering of the porphyrins, the nanoparticles exhibit collective optical properties resulted from coupling of molecular porphyrins and photocatalytic activities such as photodegradation of methyl orange (MO) pollutants and hydrogen production.« less

Synthesis, characterization and oxidation of metallic cobalt (Co) thin film into semiconducting cobalt oxide (Co3O4)thin film using microwave plasma CVD

NASA Astrophysics Data System (ADS)

Rahman Ansari, Akhalakur; Hussain, Shahir; Imran, Mohd; Abdel-wahab, M. Sh; Alshahrie, Ahmed

2018-06-01

The pure cobalt thin film was deposited on the glass substrate by using DC magnetron sputtering and then exposed to microwave assist oxygen plasma generated in microwave plasma CVD. The oxidation process of Co thin film into Co3O4 thin films with different microwave power and temperature were studied. The influences of microwave power, temperature and irradiation time were investigated on the morphology and particle size of oxide thin films. The crystal structure, chemical conformation, morphologies and optical properties of oxidized Co thin films (Co3O4) were studied by using x-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), Raman Spectroscopy and UV–vis Spectroscopy. The data of these films showed complete oxidation pure metallic cobalt (Co) into cobalt oxide (Co3O4). The optical properties were studied for calculating the direct band gaps which ranges from 1.35 to 1.8 eV.

Optical Constants of Crystallized TiO2 Coatings Prepared by Sol-Gel Process

PubMed Central

Wang, Xiaodong; Wu, Guangming; Zhou, Bin; Shen, Jun

2013-01-01

Titanium oxide coatings have been deposited by the sol-gel dip-coating method. Crystallization of titanium oxide coatings was then achieved through thermal annealing at temperatures above 400 °C. The structural properties and surface morphology of the crystallized coatings were studied by micro-Raman spectroscopy and atomic force microscopy, respectively. Characterization technique, based on least-square fitting to the measured reflectance and transmittance spectra, is used to determine the refractive indices of the crystallized TiO2 coatings. The stability of the synthesized sol was also investigated by dynamic light scattering particle size analyzer. The influence of the thermal annealing on the optical properties was then discussed. The increase in refractive index with high temperature thermal annealing process was observed, obtaining refractive index values from 1.98 to 2.57 at He-Ne laser wavelength of 633 nm. The Raman spectroscopy and atomic force microscopy studies indicate that the index variation is due to the changes in crystalline phase, density, and morphology during thermal annealing. PMID:28811410

Optical Constants of Crystallized TiO₂ Coatings Prepared by Sol-Gel Process.

PubMed

Wang, Xiaodong; Wu, Guangming; Zhou, Bin; Shen, Jun

2013-07-12

Titanium oxide coatings have been deposited by the sol-gel dip-coating method. Crystallization of titanium oxide coatings was then achieved through thermal annealing at temperatures above 400 °C. The structural properties and surface morphology of the crystallized coatings were studied by micro-Raman spectroscopy and atomic force microscopy, respectively. Characterization technique, based on least-square fitting to the measured reflectance and transmittance spectra, is used to determine the refractive indices of the crystallized TiO₂ coatings. The stability of the synthesized sol was also investigated by dynamic light scattering particle size analyzer. The influence of the thermal annealing on the optical properties was then discussed. The increase in refractive index with high temperature thermal annealing process was observed, obtaining refractive index values from 1.98 to 2.57 at He-Ne laser wavelength of 633 nm. The Raman spectroscopy and atomic force microscopy studies indicate that the index variation is due to the changes in crystalline phase, density, and morphology during thermal annealing.

Architectural transitions in Vibrio cholerae biofilms at single-cell resolution

PubMed Central

Drescher, Knut; Dunkel, Jörn; Nadell, Carey D.; van Teeffelen, Sven; Grnja, Ivan; Wingreen, Ned S.; Stone, Howard A.; Bassler, Bonnie L.

2016-01-01

Many bacterial species colonize surfaces and form dense 3D structures, known as biofilms, which are highly tolerant to antibiotics and constitute one of the major forms of bacterial biomass on Earth. Bacterial biofilms display remarkable changes during their development from initial attachment to maturity, yet the cellular architecture that gives rise to collective biofilm morphology during growth is largely unknown. Here, we use high-resolution optical microscopy to image all individual cells in Vibrio cholerae biofilms at different stages of development, including colonies that range in size from 2 to 4,500 cells. From these data, we extracted the precise 3D cellular arrangements, cell shapes, sizes, and global morphological features during biofilm growth on submerged glass substrates under flow. We discovered several critical transitions of the internal and external biofilm architectures that separate the major phases of V. cholerae biofilm growth. Optical imaging of biofilms with single-cell resolution provides a new window into biofilm formation that will prove invaluable to understanding the mechanics underlying biofilm development. PMID:26933214

Effect of solvent volume on the physical properties of aluminium doped nanocrystalline zinc oxide thin films deposited using a simplified spray pyrolysis technique

NASA Astrophysics Data System (ADS)

Jabena Begum, N.; Mohan, R.; Ravichandran, K.

2013-01-01

Aluminium doped zinc oxide (AZO) thin films were deposited by employing a low cost and simplified spray technique using a perfume atomizer from starting solutions having different volumes (10, 20, … , 50 mL) of solvent. The effect of solvent volume on the structural, electrical, optical, photoluminescence (PL) and surface morphological properties was studied. The electrical resistivity of the AZO films is remarkably influenced by the variation in the solvent volume. The X-ray diffraction profiles clearly showed that all the films have preferential orientation along the (0 0 2) plane irrespective of the solvent volume. The crystallite size was found to be in the nano range of 35-46 nm. The optical transmittance in the visible region is desirably high (>85%). The AFM images show columnar morphology with varying grain size. The PL studies revealed that the AZO film deposited from 50 mL of solvent volume has good quality with lesser defect density.

Few-cycle pulse laser induced damage threshold determination of ultra-broadband optics.

PubMed

Kafka, Kyle R P; Talisa, Noah; Tempea, Gabriel; Austin, Drake R; Neacsu, Catalin; Chowdhury, Enam A

2016-12-12

A systematic study of few-cycle pulse laser induced damage threshold (LIDT) determination was performed for commercially-available ultra-broadband optics, (i.e. chirped mirrors, silver mirrors, beamsplitters, etc.) in vacuum and in air, for single and multi-pulse regime (S-on-1). Multi-pulse damage morphology at fluences below the single-pulse LIDT was studied in order to investigate the mechanisms leading to the onset of damage. Stark morphological contrast was observed between multi-pulse damage sites formed in air versus those in vacuum. One effect of vacuum testing compared to air included suppression of laser-induced periodic surface structures (LIPSS) formation, possibly influenced by a reduced presence of damage debris. Another effect of vacuum was occasional lowering of LIDT, which appears to be due to the stress-strain performance of the coating design during laser irradiation and under the external stress of vacuum ambience. A fused silica substrate is also examined, and a non-LIPSS nanostructuring is observed on the surface. Possible mechanisms are discussed.

Harnessing the Power of Light to See and Treat Breast Cancer

DTIC Science & Technology

2014-10-01

effect of novel therapeutic agents in vivo. 15. SUBJECT TERMS optical spectroscopy, imaging , fiber-optic, molecular, screening, breast cancer 16...therapeutic agents in vivo. a. Original Statement of Work for 5 Years Aim 1: Optical imaging of margin morphology on breast lumpectomy specimens: To...evaluate the role of wide-field imaging (coverage) and high-resolution interrogation (localization) of breast margin morphology to guide surgical

Structural, magnetic, optical, dielectric, electrical and modulus spectroscopic characteristics of ZnFe2O4 spinel ferrite nanoparticles synthesized via honey-mediated sol-gel combustion method

NASA Astrophysics Data System (ADS)

Yadav, Raghvendra Singh; Kuřitka, Ivo; Vilcakova, Jarmila; Urbánek, Pavel; Machovsky, Michal; Masař, Milan; Holek, Martin

2017-11-01

This paper reports a honey-mediated green synthesis of ZnFe2O4 spinel ferrite nanoparticles and the effect of further annealing on structural, magnetic, optical, dielectric and electrical properties. X-ray diffraction study confirmed the well formation of ZnFe2O4 spinel ferrite crystal structure. Raman and Fourier transform infrared spectroscopy confirmed the formation of spinel ferrite crystal structure. The scanning electron microscopy study revealed the formation of spherical morphology at lower annealing temperature with achieved particle size 30-60 nm, whereas, octahedral like morphology at higher annealing temperature with particle size 50-400 nm. Magnetization measurements were carried out using a vibrating sample magnetometer at room temperature. The estimated magnetic parameter such as saturation magnetization (Ms), remanence (Mr) and coercivity (Hc) showed variation in value with nano-crystallite size. The highest saturation magnetization (Ms) was 12.81 emu/g for as-synthesized ZnFe2O4 spinel ferrite nanoparticles, whereas, highest coercivity (Hc) was 25.77 Oe for ZnFe2O4 nanoparticles annealed at high temperature 1000 °C. UV-Visible reflectance spectroscopy showed the band gap variation from 1.90 eV to 2.14 eV with the increase of annealing temperature. The dielectric constant and dielectric loss were decreased with frequency showing the normal behavior of spinel ferrites. The variation in conductivity is explained in terms of the variation in microstructure and variation in the mobility of charge carriers associated with the cation redistribution induced by annealing or grain size. The modulus and impedance spectroscopy study revealed the influence of bulk grain and the grain boundary on the electrical resistance and capacitance of ZnFe2O4 nanoparticles. The results presented in this work are helpful for green synthesis of well-controlled size, morphology and physical properties of ZnFe2O4 nanoparticles.

A morpho-kinematic and spectroscopic study of the bipolar nebulae: M 2-9, Mz 3, and Hen 2-104

NASA Astrophysics Data System (ADS)

Clyne, N.; Akras, S.; Steffen, W.; Redman, M. P.; Gonçalves, D. R.; Harvey, E.

2015-10-01

Context. Complex bipolar shapes can be generated either as a planetary nebula or a symbiotic system. The origin of the material ionised by the white dwarf is very different in these two scenarios, and it complicates the understanding of the morphologies of planetary nebulae. Aims: The physical properties, structure, and dynamics of the bipolar nebulae, M 2-9, Mz 3, and Hen 2-104, are investigated in detail with the aim of understanding their nature, shaping mechanisms, and evolutionary history. Both a morpho-kinematic study and a spectroscopic analysis, can be used to more accurately determine the kinematics and nature of each nebula. Methods: Long-slit optical echelle spectra are used to investigate the morpho-kinematics of M 2-9, Mz 3, and Hen 2-104. The morpho-kinematic modelling software SHAPE is used to constrain both the morphology and kinematics of each nebula by means of detailed 3D models. Near-infrared (NIR) data, as well as optical, spectra are used to separate Galactic symbiotic-type nebulae from genuine planetary nebulae by means of a 2MASS J-H/H-Ks diagram and a λ4363/Hγ vs. λ5007/Hβ diagnostic diagram, respectively. Results: The best-fitted 3D models for M 2-9, Mz 3, and Hen 2-104 provide invaluable kinematical information on the expansion velocity of its nebular components by means of synthetic spectra. The observed spectra match up very well with the synthetic spectra for each model, thus showing that each model is tightly constrained both morphologically and kinematically. Kinematical ages of the different structures of M 2-9 and Mz 3 have also been determined. Both diagnostic diagrams show M 2-9 and Hen 2-104 to fall well within the category of having a symbiotic source, whereas Mz 3 borders the region of symbiotic and young planetary nebulae in the optical diagram but is located firmly in the symbiotic region of the NIR colour-colour diagram. The optical diagnostic diagram is shown to successfully separate the two types of nebulae, however, the NIR colour-colour diagram is not as accurate in separating these objects. Conclusions: The morphology, kinematics, and evolutionary history of M 2-9, Mz 3, and Hen 2-104 are better understood using the interactive 3D modelling tool shape. The expansion velocities of the components for each nebula are better constrained and fitted with a vector field to reveal their direction of motion. The optical and NIR diagnostic diagrams used are important techniques for separating Galactic symbiotic-type nebulae from genuine planetary nebulae.

Nocturnality constrains morphological and functional diversity in the eyes of reef fishes.

PubMed

Schmitz, Lars; Wainwright, Peter C

2011-11-19

Ambient light levels are often considered to drive the evolution of eye form and function. Diel activity pattern is the main mechanism controlling the visual environment of teleost reef fish, with day-active (diurnal) fish active in well-illuminated conditions, whereas night-active (nocturnal) fish cope with dim light. Physiological optics predicts several specific evolutionary responses to dim-light vision that should be reflected in visual performance features of the eye. We analyzed a large comparative dataset on morphological traits of the eyes in 265 species of teleost reef fish in 43 different families. The eye morphology of nocturnal reef teleosts is characterized by a syndrome that indicates better light sensitivity, including large relative eye size, high optical ratio and large, rounded pupils. Improved dim-light image formation comes at the cost of reduced depth of focus and reduction of potential accommodative lens movement. Diurnal teleost reef fish, released from the stringent functional requirements of dim-light vision have much higher morphological and optical diversity than nocturnal species, with large ranges of optical ratio, depth of focus, and lens accommodation. Physical characteristics of the environment are an important factor in the evolution and diversification of the vertebrate eye. Both teleost reef fish and terrestrial amniotes meet the functional requirements of dim-light vision with a similar evolutionary response of morphological and optical modifications. The trade-off between improved dim-light vision and reduced optical diversity may be a key factor in explaining the lower trophic diversity of nocturnal reef teleosts.

Comparisons between conventional optical imaging and parametric indirect microscopic imaging on human skin detection

NASA Astrophysics Data System (ADS)

Liu, Guoyan; Gao, Kun; Liu, Xuefeng; Ni, Guoqiang

2016-10-01

We report a new method, polarization parameters indirect microscopic imaging with a high transmission infrared light source, to detect the morphology and component of human skin. A conventional reflection microscopic system is used as the basic optical system, into which a polarization-modulation mechanics is inserted and a high transmission infrared light source is utilized. The near-field structural characteristics of human skin can be delivered by infrared waves and material coupling. According to coupling and conduction physics, changes of the optical wave parameters can be calculated and curves of the intensity of the image can be obtained. By analyzing the near-field polarization parameters in nanoscale, we can finally get the inversion images of human skin. Compared with the conventional direct optical microscope, this method can break diffraction limit and achieve a super resolution of sub-100nm. Besides, the method is more sensitive to the edges, wrinkles, boundaries and impurity particles.

AFM investigation and optical band gap study of chemically deposited PbS thin films

NASA Astrophysics Data System (ADS)

Zaman, S.; Mansoor, M.; Abubakar; Asim, M. M.

2016-08-01

The interest into deposition of nanocrystalline PbS thin films, the potential of designing and tailoring both the topographical features and the band gap energy (Eg) by controlling growth parameters, has significant technological importance. Nanocrystalline thin films of lead sulfide were grown onto glass substrates by chemical bath deposition (CBD) method. The experiments were carried out by varying deposition temperature. We report on the modification of structural and optical properties as a function of deposition temperature. The morphological changes of the films were analyzed by using SEM and AFM. AFM was also used to calculate average roughness of the films. XRD spectra indicated preferred growth of cubic phase of PbS films in (200) direction with increasing deposition time. Optical properties have been studied by UV-Spectrophotometer. From the diffused reflectance spectra we have calculated the optical Eg shift from 0.649-0.636 eV with increasing deposition time.

Bottom-up production of meta-atoms for optical magnetism in visible and NIR light

NASA Astrophysics Data System (ADS)

Barois, Philippe; Ponsinet, Virginie; Baron, Alexandre; Richetti, Philippe

2018-02-01

Many unusual optical properties of metamaterials arise from the magnetic response of engineered structures of sub-wavelength size (meta-atoms) exposed to light. The top-down approach whereby engineered nanostructure of well-defined morphology are engraved on a surface proved to be successful for the generation of strong optical magnetism. It faces however the limitations of high cost and small active area in visible light where nanometre resolution is needed. The bottom-up approach whereby the fabrication metamaterials of large volume or large area results from the combination of nanochemitry and self-assembly techniques may constitute a cost-effective alternative. This approach nevertheless requires the large-scale production of functional building-blocks (meta-atoms) bearing a strong magnetic optical response. We propose in this paper a few tracks that lead to the large scale synthesis of magnetic metamaterials operating in visible or near IR light.

The optical lens coupled X-ray in-line phase contrast imaging system for the characterization of low Z materials

NASA Astrophysics Data System (ADS)

Wang, Kai; Lin, Wei; Dai, Fei; Li, Jun; Qi, Xiaobo; Lei, Haile; Liu, Yuanqiong

2018-05-01

Due to the high spatial resolution and contrast, the optical lens coupled X-ray in-line phase contrast imaging system with the secondary optical magnification is more suitable for the characterization of the low Z materials. The influence of the source to object distance and the object to scintillator distance on the image resolution and contrast is studied experimentally. A phase correlation algorithm is used for the image mosaic of a serial of X-ray phase contrast images acquired with high resolution, the resulting resolution is less than 1.0 μm, and the whole field of view is larger than 1.4 mm. Finally, the geometric morphology and the inner structure of various weakly absorbing samples and the evaporation of water in the plastic micro-shell are in situ characterized by the optical lens coupled X-ray in-line phase contrast imaging system.

Effects of Gamma Irradiation on Polyvinylidene Fluoride Thin Films

NASA Astrophysics Data System (ADS)

Madivalappa, Shivaraj; Jali, V. M.

2018-02-01

Polyvinylidene fluoride thin films were synthesized by Sol-Gel method with spin rate of 3000 rpm for 30 sec on ITO glass substrates and were annealed at 170 C. The films were irradiated by Gamma radiation with different doses (10, 30, 40 and 50 kGy). XRD and FTIR spectra have been obtained to identify the presence of α / β phases. Mean crystallite size was calculated by Scherer’s equation. Different vibrational bands were identified and percentage of β phase was determined by FTIR analysis. Optical properties like band gap, refractive index, optical activation energy have been determined. Surface morphology and compositions of pristine and gamma irradiated PVDF thin films were confirmed respectively, by SEM and Energy dispersive X-ray analysis. The comparison of the structural and optical optical properties of pristine PVDF polymer film has been made with those of the Gamma irradiated films.

Optical and structural studies of films grown thermally on zirconium surfaces

NASA Astrophysics Data System (ADS)

Morgan, J. M.; McNatt, J. S.; Shepard, M. J.; Farkas, N.; Ramsier, R. D.

2002-06-01

Variable angle IR reflection spectroscopy and atomic force microscopy are used to determine the thickness and morphology of films grown thermally on Zr surfaces in air. The density and homogeneity of these films increases with temperature in the range studied (773-873 K) and growth at the highest temperature follows cubic rate law kinetics. We demonstrate a structure-property relationship for these thermally grown films and suggest the application of IR reflectivity as an inspection method during the growth of environmentally passive films on industrial Zr components.

Enhancement of Fluorescence and Raman Scattering in Cyanine-Dye Molecules on the Surface of Silicon-Coated Silver Nanoparticles

NASA Astrophysics Data System (ADS)

Kamalieva, A. N.; Toropov, N. A.; Bogdanov, K. V.; Vartanyan, T. A.

2018-03-01

A method of formation of a composite structure based on silver nanoparticles and a thin protective silicon film (Ag NPs/Si) is developed. Enhancement of the fluorescence and Raman scattering in cyaninedye molecules deposited onto the formed nanostructure is observed. The optical properties and morphology stability of particles that are in contact with cyanine-dye solutions in organic solvents are studied. It is shown that the Ag NPs/Si composite structure can be multiply used as an SERS-active surface.

Binary Supramolecular Gel of Achiral Azobenzene with a Chaperone Gelator: Chirality Transfer, Tuned Morphology, and Chiroptical Property.

PubMed

Ji, Lukang; Ouyang, Guanghui; Liu, Minghua

2017-10-31

Binary supramolecular gels based on achiral azobenzene derivatives and a chiral chaperone gelator, long-alkyl-chain-substituted L-Histidine (abbreviated as LHC18) that could assist many nongelling acids in forming gels, were investigated in order to fabricate the chiroptical gel materials in a simple way. It was found that although the carboxylic acid-terminated achiral azobenzene derivatives could not form gels in any solvents, when mixed with LHC18 they formed the co-gels and self-assembled into various morphologies ranging from nanotubes and loose nanotubes to nanosheets, depending on the substituent groups on the azobenzene moiety. The ether linkage and the number of carboxylic acid groups attached to the azobenzene moiety played important roles. Upon gel formation, the localized molecular chirality in LHC18 could be transferred to the azobenzene moiety. Combined with the trans-cis isomerization of the azobenzene, optically and chiroptically reversible gels were generated. It was found that the gel based on azobenzene with two carboxylic acid groups and ether linkages showed clear optical reversibility but less chiroptical reversibility, whereas the gel based on azobenzene with one carboxylic acid and an ether linkage showed both optical and chiroptical reversibility. Thus, new insights into the relationship among the molecular structures of the azobenzene, self-assembled nanostructures in the gel and the optical and chiroptical reversibility were disclosed.

Characterization of ZnO:SnO{sub 2} (50:50) thin film deposited by RF magnetron sputtering technique

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cynthia, S. R.; Sanjeeviraja, C.; Ponmudi, S.

2016-05-06

Zinc oxide (ZnO) and tin oxide (SnO{sub 2}) thin films have attracted significant interest recently for use in optoelectronic application such as solar cells, flat panel displays, photonic devices, laser diodes and gas sensors because of their desirable electrical and optical properties and wide band gap. In the present study, thin films of ZnO:SnO{sub 2} (50:50) were deposited on pre-cleaned microscopic glass substrate by RF magnetron sputtering technique. The substrate temperature and RF power induced changes in structural, surface morphological, compositional and optical properties of the films have been studied.

Feasibility of spectral-domain phase-sensitive optical coherence tomography for middle ear vibrometry

PubMed Central

Nguyen-Huynh, Anh; Wang, Ruikang K.; Jacques, Steven L.; Choudhury, Niloy; Nuttall, Alfred L.

2012-01-01

Abstract. We describe a novel application of spectral-domain phase-sensitive optical coherence tomography (SD PS-OCT) to detect the tiny motions of the middle ear structures, such as the tympanic membrane and ossicular chain, and their morphological features for differential diagnosis of CHL. This technique has the potential to provide meaningful vibration of ossicles with a vibration sensitivity of ∼0.5  nm at 1 kHz of acoustic stimulation. To the best of our knowledge, this is the first demonstration of depth-resolved vibration imaging of ossicles with a PS-OCT system at a nanometer scale. PMID:22734728

Optical band gap tuning and electrical properties of polyaniline and its nanocomposites for hybrid solar cell application

NASA Astrophysics Data System (ADS)

Singh, R.; Choudhary, R. B.; Kandulna, R.

2018-05-01

Hcl doped conducting polyaniline-CdS nanocomposite has been prepared via In-situ polymerization in which cadmium nitrate was used as a source for cadmium. The structural morphology was investigated using FESEM and the presence of fibrous polyaniline and CdS nanoparticles. The synthesis of CdS and polyaniline was confirmed using the XRD analysis. I-V characteristic was used to explore the electrical behavior of PANI and its nanocoposites. Optical properties were studied and minimum band gap with highest band absorbance was found for synergistic concentration PANI-CdS (10%) for solar cells application.

Mathematical modelling of thin films growth and calculation of coefficients reflection, transmission and absorption waves

NASA Astrophysics Data System (ADS)

Istratov, A. V.; Gerke, M. N.

2018-01-01

Progress in nano- and microsystem technology is directly related to the development of thin-film technologies. At the present time, thin metal films can serve as the basis for the creation of new instruments for nanoelectronics. One of the important parameters of thin films affecting the characteristics of devices is their optical properties. That is why the island structures, whose optical properties, can change in a wide range depending on their morphology, are of increasing interest. However, despite the large amount of research conducted by scientists from different countries, many questions about the optimal production and use of thin films remain unresolved.

Optical and structural properties of CsI thin film photocathode

NASA Astrophysics Data System (ADS)

Triloki; Rai, R.; Singh, B. K.

2015-06-01

In the present work, the performance of a cesium iodide thin film photocathode is studied in detail. The optical absorbance of cesium iodide films has been analyzed in the spectral range from 190 nm to 900 nm. The optical band gap energy of 500 nm thick cesium iodide film is calculated from the absorbance data using a Tauc plot. The refractive index is estimated from the envelope plot of transmittance data using Swanepoel's method. The absolute quantum efficiency measurement has been carried out in the wavelength range from 150 nm to 200 nm. The crystallographic nature and surface morphology are investigated by X-ray diffraction and transmission electron microscopy techniques. In addition, the elemental composition result obtained by energy dispersive X-ray analysis is also reported in the present work.

Optical, mechanical and structural properties of PMMA/SiO2 nanocomposite thin films

NASA Astrophysics Data System (ADS)

Soni, Gyanesh; Srivastava, Subodh; Soni, Purushottam; Kalotra, Pankaj; Vijay, Y. K.

2018-01-01

We have fabricated PMMA/SiO2 nanocomposite flexible thin films of 60 μm thicknesses by using solution casting method in the presence of transverse electric field. In this paper, we have investigated the effect of SiO2 nanoparticle (NP) loading on optical and mechanical properties of the composite thin film. The SEM images show that nanocomposite thin films have a smoother and uniform morphology. The transmittance peak near 1103 cm-1 in FT-IR spectrum confirms the presence of SiO2 NPs in the composite thin film. It is observed that optical bandgap decreases with an increase in the SiO2 NP concentration. Dynamic mechanical analysis shows that presence of SiO2 NP enhances the mechanical strength of the composite thin film.

Lanthanum cerate (La2Ce2O7): hydrothermal synthesis, characterization and optical properties

NASA Astrophysics Data System (ADS)

Khademinia, Shahin; Behzad, Mahdi

2015-03-01

La2Ce2O7 nano-powders were synthesized via a hydrothermal reaction in a deionized water (S 1) and in a 2 M NaOH aqueous solution (S 2) at 180 °C for 48 h. La(NO3)3·H2O and (NH4)2Ce(NO3)6 were used in the stoichiometric 1:1 La:Ce molar ratio as raw materials. The obtained materials were crystallized in a cubic crystal structure with space group. The synthesized materials were characterized by powder X-ray diffraction technique and Fourier-transform infrared spectroscopy. To investigate the effect of the basic solution on the morphology of the obtained materials, the morphologies of the synthesized materials were studied by field emission scanning electron microscopy technique. The technique showed that the morphology of La2Ce2O7 samples changed from grain to rod-like structure in presence of the basic solution. Cell parameter refinements showed that these parameters were larger for S2 than those for S 1. Photoluminescence and ultraviolet visible spectra of the synthesized nanomaterials were also investigated.

Surface characterization of carbon fiber polymer composites and aluminum alloys after laser interference structuring

DOE PAGES

Sabau, Adrian S.; Greer, Clayton M.; Chen, Jian; ...

2016-05-03

Here, the increasing use of Carbon Fiber-reinforced Polymer matrix Composites (CFPC) and aluminum alloys as lightweight materials in the automotive and aerospace industries demands enhanced surface preparation and control of surface morphology prior to joining. In this study, surfaces of both composite and aluminum were prepared for joining using an Nd:YAG laser in a two-beam interference setup, enabling the (a) structuring of the AL 5182 surface, (b) removal of the resin layer on top of carbon fibers, and (c) structuring of the carbon fibers. CFPC specimens of T700S carbon fiber, Prepreg - T8 3 epoxy, 5 ply thick, 0/90o plaquesmore » were used. The effect of laser fluence, scanning speed, and number of shots-per-spot was investigated on the removal rate of the resin without an excessive damage of the fibers. Optical micrographs, 3D imaging, and scanning electron microscope (SEM) imaging were used to study the effect of the laser processing on surface morphology.« less

Synthesis and characterization of structural, morphological and photosensor properties of Cu0.1Zn0.9S thin film prepared by a facile chemical method

NASA Astrophysics Data System (ADS)

Gubari, Ghamdan M. M.; Ibrahim Mohammed S., M.; Huse, Nanasaheb P.; Dive, Avinash S.; Sharma, Ramphal

2018-05-01

The Cu0.1Zn0.9S thin film was grown by facile chemical bath deposition (CBD) method on glass substrates at 60°C. The structural, morphological, photosensor properties of the as-grown thin film has been investigated. The structural and phase confirmation of the as-grown thin film was carried out by X-ray diffraction (XRD) technique and Raman spectroscopy. The FE-SEM images showed that the thin films are well covered with material on an entire glass substrate. From the optical absorption spectrum, the direct band gap energy for the Cu0.1Zn0.9S thin film was found to be ˜3.16 eV at room temperature. The electrical properties were measured at room temperature in the voltage range ±2.5 V, showed a drastic enhancement in current under light illumination with the highest photosensitivity of ˜72 % for 260 W.

Hydrothermal-electrochemical growth of heterogeneous ZnO: Co films

NASA Astrophysics Data System (ADS)

Yilmaz, Ceren; Unal, Ugur

2017-10-01

This study demonstrates the preparation of heterogeneous ZnO: Co nanostructures via hydrothermal-electrochemical deposition at 130 °C and -1.1 V (vs Ag/AgCl (satd)) in dimethyl sulfoxide (DMSO)-H2O mixture. Under the stated conditions, ZnO: Co nanostructures grow preferentially along (002) direction. Strength of directional growth progressively increases with the increasing concentration of Co(II) in the deposition bath. Films are composed of hexagonal Wurtzite ZnO, metallic cobalt, and mixed cobalt oxide on the surface and cobalt(II) oxide in deeper levels. Increasing the Co(II) concentration in the deposition bath results in different morphological features as well as phase separation. Platelets, sponge-like structures, cobalt-rich spheres, microislands of cobalt-rich spheres which are interconnected by ZnO network can be synthesized by adjusting [Co(II)]: [Zn(II)] ratio. Growth mechanisms giving rise to these particular structures, surface morphology, crystal structure, phase purity, chemical binding characteristics, and optical properties of the deposits are discussed in detail.

Using a double-doping strategy to improve physical properties of nanostructured CdO films

NASA Astrophysics Data System (ADS)

Aydin, R.; Sahin, B.

2018-06-01

In this present study nanostructured dually doped samples of Cd1‑x‑yMgxMyO (M: Sn, Pb, Bi) are synthesized by SILAR method. The effects of the mono and dual doping on the structural, morphological and optoelectronic characteristics of CdO nanoparticles are examined. The SEM images verify that deposited CdO films are nano-sized. Also the SEM computations demonstrated that the morphological surface structures of the films were influenced from the Mg mono doping and (Mg, Sn), (Mg, Pb) and (Mg, Bi) dual doping. The XRD designs specified that all the CdO samples have polycrystalline structure exhibiting cubic crystal form with dominant peaks of (111) and (220). The results display that Mg and (Mg, Sn), (Mg, Pb) and (Mg, Bi) ions were successfully doped into CdO film matrix. The UV spectroscopy results show that the optical energy band gap of the CdO films, ranging from 2.21 to 2.66 eV, altered with the dopant materials.

Systematic investigation of structural and morphological studies on doped TiO2 nanoparticles for solar cell applications

NASA Astrophysics Data System (ADS)

Murugadoss, G.; Jayavel, R.; Rajesh Kumar, M.

2014-12-01

Optical, structural and thermal properties of the doped with different ions (transition metals, other metals or post transition metals, non-metals, alkali metals and lanthanides) in TiO2 nanocrystals were investigated. The doped nanoparticles were synthesized by modified chemical method. Ethanol-deionised water mixer (20:1) was used as solvent for synthesize of the undoped and doped TiO2 nanoparticles. Systematic studies on structural and morphological changes by thermal treatment on TiO2 were examined. It has been observed that with Eu and Al doping TiO2, the phase transition temperature for anatase to rutile phase increased. Blue and red shifting absorptions were observed for doped TiO2 in visible region. Among the dopant, significant blue shift was obtained for Cu, Cd, Ag, Y, Ce and In doped TiO2 and red shift was obtained for Zr, Sm, Al, Na, S, Fe, Ni, Eu and Gd doped TiO2 nanoparticles.

Morphological Evolution of Block Copolymer Particles: Effect of Solvent Evaporation Rate on Particle Shape and Morphology.

PubMed

Shin, Jae Man; Kim, YongJoo; Yun, Hongseok; Yi, Gi-Ra; Kim, Bumjoon J

2017-02-28

Shape and morphology of polymeric particles are of great importance in controlling their optical properties or self-assembly into unusual superstructures. Confinement of block copolymers (BCPs) in evaporative emulsions affords particles with diverse structures, including prolate ellipsoids, onion-like spheres, oblate ellipsoids, and others. Herein, we report that the evaporation rate of solvent from emulsions encapsulating symmetric polystyrene-b-polybutadiene (PS-b-PB) determines the shape and internal nanostructure of micron-sized BCP particles. A distinct morphological transition from the ellipsoids with striped lamellae to the onion-like spheres was observed with decreasing evaporation rate. Experiments and dissipative particle dynamics (DPD) simulations showed that the evaporation rate affected the organization of BCPs at the particle surface, which determined the final shape and internal nanostructure of the particles. Differences in the solvent diffusion rates in PS and PB at rapid evaporation rates induced alignment of both domains perpendicular to the particle surface, resulting in ellipsoids with axial lamellar stripes. Slower evaporation rates provided sufficient time for BCP organization into onion-like structures with PB as the outermost layer, owing to the preferential interaction of PB with the surroundings. BCP molecular weight was found to influence the critical evaporation rate corresponding to the morphological transition from ellipsoid to onion-like particles, as well as the ellipsoid aspect ratio. DPD simulations produced morphologies similar to those obtained from experiments and thus elucidated the mechanism and driving forces responsible for the evaporation-induced assembly of BCPs into particles with well-defined shapes and morphologies.

Morphological study on small molecule acceptor-based organic solar cells with efficiencies beyond 7% (Presentation Recording)

NASA Astrophysics Data System (ADS)

Ma, Wei; Yan, He

2015-10-01

Despite the essential role of fullerenes in achieving best-performance organic solar cells (OSCs), fullerene acceptors have several drawbacks including poor light absorption, high-cost production and purification. For this reason, small molecule acceptor (SMA)-based OSCs have attracted much attention due to the easy tunability of electronic and optical properties of SMA materials. In this study, polymers with temperature dependent aggregation behaviors are combined with various small molecule acceptor materials, which lead to impressive power conversion efficiencies of up to 7.3%. The morphological and aggregation properties of the polymer:small molecule blends are studied in details. It is found that the temperature-dependent aggregation behavior of polymers allows for the processing of the polymer solutions at moderately elevated temperature, and more importantly, controlled aggregation and strong crystallization of the polymer during the film cooling and drying process. This results in a well-controlled and near-ideal polymer:small molecule morphology that is controlled by polymer aggregation during warm casting and thus insensitive to the choice of small molecules. As a result, several cases of highly efficient (PCE between 6-7.3%) SMA OSCs are achieved. The second part of this presentation will describe the morphology of a new small molecule acceptor with a unique 3D structure. The relationship between molecular structure and morphology is revealed.

Color from hierarchy: Diverse optical properties of micron-sized spherical colloidal assemblies.

PubMed

Vogel, Nicolas; Utech, Stefanie; England, Grant T; Shirman, Tanya; Phillips, Katherine R; Koay, Natalie; Burgess, Ian B; Kolle, Mathias; Weitz, David A; Aizenberg, Joanna

2015-09-01

Materials in nature are characterized by structural order over multiple length scales have evolved for maximum performance and multifunctionality, and are often produced by self-assembly processes. A striking example of this design principle is structural coloration, where interference, diffraction, and absorption effects result in vivid colors. Mimicking this emergence of complex effects from simple building blocks is a key challenge for man-made materials. Here, we show that a simple confined self-assembly process leads to a complex hierarchical geometry that displays a variety of optical effects. Colloidal crystallization in an emulsion droplet creates micron-sized superstructures, termed photonic balls. The curvature imposed by the emulsion droplet leads to frustrated crystallization. We observe spherical colloidal crystals with ordered, crystalline layers and a disordered core. This geometry produces multiple optical effects. The ordered layers give rise to structural color from Bragg diffraction with limited angular dependence and unusual transmission due to the curved nature of the individual crystals. The disordered core contributes nonresonant scattering that induces a macroscopically whitish appearance, which we mitigate by incorporating absorbing gold nanoparticles that suppress scattering and macroscopically purify the color. With increasing size of the constituent colloidal particles, grating diffraction effects dominate, which result from order along the crystal's curved surface and induce a vivid polychromatic appearance. The control of multiple optical effects induced by the hierarchical morphology in photonic balls paves the way to use them as building blocks for complex optical assemblies--potentially as more efficient mimics of structural color as it occurs in nature.

Color from hierarchy: Diverse optical properties of micron-sized spherical colloidal assemblies

PubMed Central

Vogel, Nicolas; Utech, Stefanie; England, Grant T.; Shirman, Tanya; Phillips, Katherine R.; Koay, Natalie; Burgess, Ian B.; Kolle, Mathias; Weitz, David A.; Aizenberg, Joanna

2015-01-01

Materials in nature are characterized by structural order over multiple length scales have evolved for maximum performance and multifunctionality, and are often produced by self-assembly processes. A striking example of this design principle is structural coloration, where interference, diffraction, and absorption effects result in vivid colors. Mimicking this emergence of complex effects from simple building blocks is a key challenge for man-made materials. Here, we show that a simple confined self-assembly process leads to a complex hierarchical geometry that displays a variety of optical effects. Colloidal crystallization in an emulsion droplet creates micron-sized superstructures, termed photonic balls. The curvature imposed by the emulsion droplet leads to frustrated crystallization. We observe spherical colloidal crystals with ordered, crystalline layers and a disordered core. This geometry produces multiple optical effects. The ordered layers give rise to structural color from Bragg diffraction with limited angular dependence and unusual transmission due to the curved nature of the individual crystals. The disordered core contributes nonresonant scattering that induces a macroscopically whitish appearance, which we mitigate by incorporating absorbing gold nanoparticles that suppress scattering and macroscopically purify the color. With increasing size of the constituent colloidal particles, grating diffraction effects dominate, which result from order along the crystal’s curved surface and induce a vivid polychromatic appearance. The control of multiple optical effects induced by the hierarchical morphology in photonic balls paves the way to use them as building blocks for complex optical assemblies—potentially as more efficient mimics of structural color as it occurs in nature. PMID:26290583

Optical and structural properties of colloidal zirconia nanoparticles prepared by arc discharge in liquid

NASA Astrophysics Data System (ADS)

Peymani forooshani, Reza; Poursalehi, Reza; Yourdkhani, Amin

2018-01-01

Zirconia is one of the important ceramic materials with unique properties such as high melting point, high ionic conductivity, high mechanical properties and low thermal conductivity. Therefore, zirconia is one of the useful materials in refractories, thermal barriers, cutting tools, oxygen sensors electrolytes, catalysis, catalyst supports and solid oxide fuel cells. Recently, direct current (DC) arc discharge is extensively employed to synthesis of metal oxide nanostructures in liquid environments. The aim of this work is the synthesis of colloidal zirconia nanoparticles by DC arc discharge method in water as a medium. Arc discharge was ignited between two pure zirconium electrodes in water. Optical and structural properties of prepared colloidal nanoparticles were investigated. Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD) and UV-visible spectroscopy, were employed for characterization of particle size, morphology, crystal structure and optical properties, respectively. SEM images demonstrate that the nanoparticles are spherical in shape with an average size lower than 38 nm. The XRD patterns of the nanoparticles were consistent with tetragonal and monoclinic zirconia crystal structures. The optical transmission spectra of the colloidal solution show optical characteristic of zirconia nanoparticles as a wide band gap semiconductor with no absorption peak in visible wavelength with the considerable amount of oxygen deficiency. Oxidation of colloidal nanoparticles in water could be explained via reaction with either dissociated oxygen from water in hot plasma region or with dissolved oxygen in water. The results provide a simple and flexible method for preparation of zirconia nanoparticles with a capability of mass production without environmental footprints.

Investigations of nanodimensional Al{sup 2}O{sup 3} films deposited by ion-plasma sputtering onto porous silicon

DOE Office of Scientific and Technical Information (OSTI.GOV)

Seredin, P. V., E-mail: paul@phys.vsu.ru; Lenshin, A. S.; Goloshchapov, D. L.

2015-07-15

The purpose of this study is the deposition of nanodimensional Al{sup 2}O{sup 3} films on the surface of nanoporous silicon and also fundamental investigations of the structural, optical, and morphological properties of these materials. Analyzing the results obtained here, it is possible to state that ultrathin nanostructured Al{sup 2}O{sup 3} films can be obtained in the form of threads oriented in one direction and located at a distance of 300–500 nm from each other using ion-plasma sputtering on a layer of porous silicon. Such a mechanism of aluminum-oxide growth is conditioned by the crystallographic orientation of the initial single-crystalline siliconmore » wafer used to fabricate the porous layer. The results of optical spectroscopy show that the Al{sup 2}O{sup 3}/por-Si/Si(111) heterophase structure perfectly transmits electromagnetic radiation in the range of 190–900 nm. The maximum in the dispersion of the refractive index obtained for the Al{sup 2}O{sup 3} film grown on por-Si coincides with the optical-absorption edge for aluminum oxide and is located in the region of ∼5.60 eV. This fact is confirmed by the results of calculations of the optical-absorption spectrum of the Al{sup 2}O{sup 3}/por-Si/Si(lll) heterophase structure. The Al{sup 2}O{sup 3} films formed on the heterophase-structure surface in the form of nanodimensional structured threads can serve as channels of optical conduction and can be rather efficiently introduced into conventional technologies, which are of great importance in microelectronics and optoelectronics.« less

Visible rodent brain-wide networks at single-neuron resolution

PubMed Central

Yuan, Jing; Gong, Hui; Li, Anan; Li, Xiangning; Chen, Shangbin; Zeng, Shaoqun; Luo, Qingming

2015-01-01

There are some unsolvable fundamental questions, such as cell type classification, neural circuit tracing and neurovascular coupling, though great progresses are being made in neuroscience. Because of the structural features of neurons and neural circuits, the solution of these questions needs us to break through the current technology of neuroanatomy for acquiring the exactly fine morphology of neuron and vessels and tracing long-distant circuit at axonal resolution in the whole brain of mammals. Combined with fast-developing labeling techniques, efficient whole-brain optical imaging technology emerging at the right moment presents a huge potential in the structure and function research of specific-function neuron and neural circuit. In this review, we summarize brain-wide optical tomography techniques, review the progress on visible brain neuronal/vascular networks benefit from these novel techniques, and prospect the future technical development. PMID:26074784

Optical, thermal and morphological study of ZnS doped PVA polymer nano composites

NASA Astrophysics Data System (ADS)

Guruswamy, B.; Ravindrachary, V.; Shruthi, C.; Sagar, Rohan N.; Hegde, Shreedatta

2018-05-01

The effect of ZnS nano particle doping on optical, thermal properties and morphological study of the PVA polymer has been investigated using FTIR, UV-Visible and TGA, FESEM techniques. Nano sized ZnS particles were synthesized by a simple wet chemical route. Pure and ZnS/PVA nano composites were prepared using solution casting technique. The FTIR study confirms that the ZnS nano particles interacts with the OH group of PVA polymer and forms the complex. The formation of these complexes affects the optical and thermal properties of the composite. The changes in optical properties were studied using UV-Vis absorption method. The variation in thermal property was analysed using TGA results. The modified surface morphology analysis was carried out using FESEM.

Simple synthesis of PbSe nanocrystals and their self-assembly into 2D ‘flakes’ and 1D ‘ribbons’ structures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Díaz-Torres, E., E-mail: ediaz@cinvestav.mx; Ortega-López, M.; Matsumoto, Y.

2016-08-15

Highlights: • PbSe is obtained in a simple way by the co-precipitation method at low-temperature. • The structural, morphological and optical properties of PbSe were studied. • Adding NH{sub 4}OH to the precursor solutions influences on the morphology. • 2D- and 1D-PbSe structures assemble by oriented attachment. • PbSe can be a potential candidate for thermoelectric applications. - Abstract: This work presents a simple and low-temperature method to prepare a variety of Lead selenide (PbSe) nanostructures, using aqueous solutions of Pb(NO{sub 3}){sub 2} and NaHSe. Nanostructures with different morphology were obtained by varying the Pb:Se molar ratio, as well asmore » the mixing sequence of NH{sub 4}OH with either Pb(NO{sub 3}){sub 2} or NaHSe. Nanoparticles with different shapes (spherical and octahedral), and self-assembled structures (flakes and ribbons) were observed by Transmission Electron Microscopy. X-ray results confirmed that the PbSe rock-salt crystalline structure was obtained for all of the prepared samples. The crystal size is in the order of 7.3 to 8.9 nm for single nanocrystals. The absorption spectra of the samples show exciton absorption bands at 1395 nm and 1660 nm. This material could be used to develop more advanced structures for thermoelectric generators.« less

Structure-property evolution during polymer crystallization

NASA Astrophysics Data System (ADS)

Arora, Deepak

The main theme of this research is to understand the structure-property evolution during crystallization of a semicrystalline thermoplastic polymer. A combination of techniques including rheology, small angle light scattering, differential scanning calorimetry and optical microscopy are applied to follow the mechanical and optical properties along with crystallinity and the morphology. Isothermal crystallization experiments on isotactic poly-1-butene at early stages of spherulite growth provide quantitative information about nucleation density, volume fraction of spherulites and their crystallinity, and the mechanism of connecting into a sample spanning structure. Optical microscopy near the fluid-to-solid transition suggests that the transition, as determined by time-resolved mechanical spectroscopy, is not caused by packing/jamming of spherulites but by the formation of a percolating network structure. The effect of strain, Weissenberg number (We ) and specific mechanical work (w) on rate of crystallization (nucleation followed by growth) and on growth of anisotropy was studied for shear-induced crystallization of isotactic poly-1-butene. The samples were sheared for a finite strain at the beginning of the experiment and then crystallized without further flow (Janeschitz-Kriegl protocol). Strain requirements to attain steady state/leveling off of the rate of crystallization were found to be much larger than the strain needed to achieve steady state of flow. The large strain and We>1 criteria were also observed for morphological transition from spherulitic growth to oriented growth. An apparatus for small angle light scattering (SALS) and light transmission measurements under shear was built and tested at the University of Massachusetts Amherst. As a new development, the polarization direction can be rotated by a liquid crystal polarization rotator (LCPR) with a short response time of 20 ms. The experiments were controlled and analyzed with a LabVIEW(TM) based code (LabVIEW(TM) 7.1) in real time. The SALS apparatus was custom built for ExxonMobil Research in Clinton NJ.

Synthesis and Characterization of Pure Copper Nanostructures Using Wood Inherent Architecture as a Natural Template

NASA Astrophysics Data System (ADS)

Dong, Youming; Wang, Kaili; Tan, Yi; Wang, Qingchun; Li, Jianzhang; Mark, Hughes; Zhang, Shifeng

2018-04-01

The inherent sophisticated structure of wood inspires researchers to use it as a natural template for synthesizing functional nanoparticles. In this study, pure copper nanoparticles were synthesized using poplar wood as a natural inexpensive and renewable template. The crystal structure and morphologies of the copper nanoparticles were characterized by X-ray diffraction and field emission scanning electron microscopy. The optical properties, antibacterial properties, and stability of the hybrid wood materials were also tested. Due to the hierarchical and anisotropic structure and electron-rich components of wood, pure copper nanoparticles with high stability were synthesized with fcc structure and uniform sizes and then assembled into corncob-like copper deposits along the wood cell lumina. The products of nanoparticles depended strongly on the initial OH- concentration. With an increase in OH- concentration, Cu2O gradually decreased and Cu remained. Due to the restrictions inherent in wood structure, the derived Cu nanoparticles showed similar grain size in spite of increased Cu2+ concentration. This combination of Cu nanostructures and wood exhibited remarkable optical and antibacterial properties.

Method for Calculating the Optical Diffuse Reflection Coefficient for the Ocular Fundus

NASA Astrophysics Data System (ADS)

Lisenko, S. A.; Kugeiko, M. M.

2016-07-01

We have developed a method for calculating the optical diffuse reflection coefficient for the ocular fundus, taking into account multiple scattering of light in its layers (retina, epithelium, choroid) and multiple refl ection of light between layers. The method is based on the formulas for optical "combination" of the layers of the medium, in which the optical parameters of the layers (absorption and scattering coefficients) are replaced by some effective values, different for cases of directional and diffuse illumination of the layer. Coefficients relating the effective optical parameters of the layers and the actual values were established based on the results of a Monte Carlo numerical simulation of radiation transport in the medium. We estimate the uncertainties in retrieval of the structural and morphological parameters for the fundus from its diffuse reflectance spectrum using our method. We show that the simulated spectra correspond to the experimental data and that the estimates of the fundus parameters obtained as a result of solving the inverse problem are reasonable.

Nano ZnO embedded in Chitosan matrix for vibration sensor application

NASA Astrophysics Data System (ADS)

Praveen, E.; Murugan, S.; Jayakumar, K.

2015-06-01

Biopolymer Chitosan is embedded with various concentration of ZnO nano particle and such a bio-nano composite electret has been fabricated by casting method. The morphological, structural, optical and electrical characterization of the bio-nano composite electret film have been carried out. Isolation and piezoelectric measurements of bio-nano composite have also been carried out indicating the possibility of using it as a mechanical sensor element.

Morphology of human sweat ducts observed by optical coherence tomography and their frequency of resonance in the terahertz frequency region

NASA Astrophysics Data System (ADS)

Tripathi, Saroj R.; Miyata, Eisuke; Ishai, Paul Ben; Kawase, Kodo

2015-03-01

It is crucial to understand the various biological effects induced by terahertz (THz) electromagnetic waves with the rapid development of electronic and photonic devices operating in the THz frequency region. The presence of sweat glands plays an important role in THz wave interactions with human skin. We investigated the morphological features of sweat ducts using optical coherence tomography (OCT) to further understand such phenomena. We observed remarkable features of the ducts, such as their clear helical structure. The intersubject and intrasubject variations in the diameter of sweat ducts were considerably smaller than the variations in other structural parameters, such as length and number of turns. Based on the sweat duct dimensions and THz dielectric properties of skin measured using terahertz time-domain spectroscopy (THz-TDS), we calculated the resonating frequency of the sweat duct under the assumption of it functioning as a helical antenna. Here, we show that the resonance frequency in the axial mode of operation lies in the THz wave region with a centre frequency of 0.44 +/- 0.07 THz. We expect that these findings will further our understanding of the various health consequences of the interaction of THz waves with human beings.

Influence of acid and alkaline sources on optical, structural and photovoltaic properties of CdSe nanoparticles precipitated from aqueous solution

NASA Astrophysics Data System (ADS)

Coria-Monroy, C. Selene; Sotelo-Lerma, Mérida; Hu, Hailin

2016-06-01

CdSe is a widely researched material for photovoltaic applications. One of the most important parameters of the synthesis is the pH value, since it determines the kinetics and the mechanism of the reaction and in consequence, the optical and morphological properties of the products. We present the synthesis of CdSe in solution with strict control of pH and the comparison of ammonia and KOH as alkaline sources and diluted HCl as acid medium. CdSe formation was monitored with photoluminescence emission spectra (main peak in 490 nm, bandgap of CdSe nanoparticles). XRD patterns indicated that CdSe nanoparticles are mainly of cubic structure for ammonia and HCl, but the hexagonal planes appear with KOH. Product yield decreases with pH and also decreases with KOH at constant pH value since ammonia has a double function, as complexing agent and alkaline source. Changes in morphology were observed in SEM images as well with the different alkaline source. The effect of alkaline sources on photovoltaic performance of hybrid organic solar cells with CdSe and poly(3-hexylthiophene) as active layers was clearly observed, indicating the importance of synthesis conditions on optoelectronic properties of promising semiconductor nanomaterials for solar cell applications.

Synthesis of Ag-Cu-Pd alloy thin films by DC-magnetron sputtering: Case study on microstructures and optical properties

NASA Astrophysics Data System (ADS)

Rezaee, Sahar; Ghobadi, Nader

2018-06-01

The present study aims to investigate optical properties of Ag-Cu-Pd alloy thin films synthesized by DC-magnetron sputtering method. The thin films are deposited on the glass and silicon substrates using Argon gas and Ag-Cu-Pd target. XRD analysis confirms the successful growth of Ag, Cu, and Pd NPs with FCC crystalline structure. Moreover, UV-visible absorption spectroscopy is applied to determine optical properties of the prepared samples which are affected by changes in surface morphology. The existence of single surface plasmon resonance (SPR) peak near 350 nm proves the formation of silver nanoparticles with a slight red shift through increasing deposition time. Ineffective thickness method (ITM) and Derivation of ineffective thickness method (DITM) are applied to extract optical band gap and transition type via absorption spectrum. SEM and AFM analyses show the distribution of near-spherical nanoparticles covering the surface of thin films. Furthermore, thickness variation affects the grain size. In addition, TEM image reveals the uniform size distribution of nanoparticles with an average particle size of about 15 nm. The findings show that increasing grain size and crystallite order along with the decrease of structural defect and disorders decrease optical band gap from 3.86 eV to 2.58 eV.

New possibility on InZnO nano thin film for green emissive optoelectronic devices

NASA Astrophysics Data System (ADS)

Sugumaran, Sathish; Noor Bin Ahmad, Mohd; Faizal Jamlos, Mohd; Bellan, Chandar Shekar; Chandran, Sharmila; Sivaraj, Manoj

2016-04-01

Indium zinc oxide (InZnO) nano thin film was prepared from InZnO nanoparticles (NPs) by thermal evaporation technique. Fourier transform infrared spectroscopy showed the presence of metal-oxide bond. X-ray diffraction pattern revealed the mixed phase structure. The presence of elements In, Zn and O were identified from energy dispersive X-ray analysis. Size of the NPs was found to be 171 and 263 nm by transmission electron microscopy. Scanning electron microscopy image showed the spherical shape uniform morphology with uniform distribution grains. Photoluminescence spectrum exhibited a broad green emission for InZnO nano thin film. The acquired results of structure, smooth morphology and photoluminescence property suggested that the InZnO nano thin film to be a promising material for room temperature green emissive optoelectronic, laser diodes, solar cells and other optical devices.

Phytosynthesis and applications of bioactive SnO{sub 2} nanoparticles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vidhu, V.K.; Philip, Daizy, E-mail: philipdaizy@yahoo.co.in

2015-03-15

A facile, eco-friendly, cost effective and versatile synthesis of SnO{sub 2} nanoparticles of size in the range 2.2–3.2 nm using fenugreek seeds is reported. The structural and morphological properties of SnO{sub 2} nanoparticles have been studied using X-ray diffraction, Transmission Electron Microscopy and Energy Dispersive X-ray spectroscopy. UV–visible spectra show a blue shift of the absorption band arising from quantum size effect. Studies on thermal conductivity, viscosity, antibacterial and antioxidant properties of the synthesized SnO{sub 2} nanoparticles highlight the possible applications in nanofluids and biomedical field. - Graphical abstract: Display Omitted - Highlights: • Bioactive SnO{sub 2} nanoparticles are synthesizedmore » using Fenugreek seeds. • Structural, morphological and optical characterizations have been done. • Thermal conductivity and rheological properties are reported. • Antioxidant and antibacterial activities are highlighted.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sabau, Adrian S.; Greer, Clayton M.; Chen, Jian

Here, the increasing use of Carbon Fiber-reinforced Polymer matrix Composites (CFPC) and aluminum alloys as lightweight materials in the automotive and aerospace industries demands enhanced surface preparation and control of surface morphology prior to joining. In this study, surfaces of both composite and aluminum were prepared for joining using an Nd:YAG laser in a two-beam interference setup, enabling the (a) structuring of the AL 5182 surface, (b) removal of the resin layer on top of carbon fibers, and (c) structuring of the carbon fibers. CFPC specimens of T700S carbon fiber, Prepreg - T8 3 epoxy, 5 ply thick, 0/90o plaquesmore » were used. The effect of laser fluence, scanning speed, and number of shots-per-spot was investigated on the removal rate of the resin without an excessive damage of the fibers. Optical micrographs, 3D imaging, and scanning electron microscope (SEM) imaging were used to study the effect of the laser processing on surface morphology.« less

Morphology Development in Solution-Processed Functional Organic Blend Films: An In Situ Viewpoint.

PubMed

Richter, Lee J; DeLongchamp, Dean M; Amassian, Aram

2017-05-10

Solution-processed organic films are a facile route to high-speed, low cost, large-area deposition of electrically functional components (transistors, solar cells, emitters, etc.) that can enable a diversity of emerging technologies, from Industry 4.0, to the Internet of things, to point-of-use heath care and elder care. The extreme sensitivity of the functional performance of organic films to structure and the general nonequilibrium nature of solution drying result in extreme processing-performance correlations. In this Review, we highlight insights into the fundamentals of solution-based film deposition afforded by recent state-of-the-art in situ measurements of functional film drying. Emphasis is placed on multimodal studies that combine surface-sensitive X-ray scattering (GIWAXS or GISAXS) with optical characterization to clearly define the evolution of solute structure (aggregation, crystallinity, and morphology) with film thickness.

Two-dimensional and three-dimensional evaluation of the deformation relief

NASA Astrophysics Data System (ADS)

Alfyorova, E. A.; Lychagin, D. V.

2017-12-01

This work presents the experimental results concerning the research of the morphology of the face-centered cubic single crystal surface after compression deformation. Our aim is to identify the method of forming a quasiperiodic profile of single crystals with different crystal geometrical orientation and quantitative description of deformation structures. A set of modern methods such as optical and confocal microscopy is applied to determine the morphology of surface parameters. The results show that octahedral slip is an integral part of the formation of the quasiperiodic profile surface starting with initial strain. The similarity of the formation process of the surface profile at different scale levels is given. The size of consistent deformation regions is found. This is 45 µm for slip lines ([001]-single crystal) and 30 µm for mesobands ([110]-single crystal). The possibility of using two- and three-dimensional roughness parameters to describe the deformation structures was shown.

Optical, structural and morphological properties of zirconia nanoparticles prepared by laser ablation in liquids

DOE Office of Scientific and Technical Information (OSTI.GOV)

Borodina, T I; Val'yano, G E; Gololobova, O A

2014-09-30

Absorption, fluorescence and Raman spectra, the structural composition and morphology of zirconia nanoparticles synthesised via the laser ablation of a metal in water and aqueous solutions of the sodium dodecyl sulphate (SDS) surfactant have been studied using absorption spectroscopy, Raman spectroscopy, X-ray diffraction and scanning electron microscopy. The results demonstrate that, exposing zirconium to intense nanosecond laser pulses at a high repetition rate in these liquids, one can obtain stable cubic, tetragonal and monoclinic crystalline phases of nanozirconia with a particle size in the range 40 – 100 nm and a Zr – SDS organic – inorganic composite. The absorptionmore » and fluorescence of the synthesised zirconia strongly depend on the SDS concentration in the starting solution. The gas – vapour bubbles forming during ablation are shown to serve as templates for the formation of hollow nanoand microstructures. (nanostructures)« less

Annealing Effects on Structure and Optical Properties of Diamond-Like Carbon Films Containing Silver.

PubMed

Meškinis, Šarūnas; Čiegis, Arvydas; Vasiliauskas, Andrius; Šlapikas, Kęstutis; Gudaitis, Rimantas; Yaremchuk, Iryna; Fitio, Volodymyr; Bobitski, Yaroslav; Tamulevičius, Sigitas

2016-12-01

In the present study, diamond-like carbon films with embedded Ag nanoparticles (DLC:Ag) were deposited by reactive magnetron sputtering. Structure of the films was investigated by Raman scattering spectroscopy. Atomic force microscopy was used to define thickness of DLC:Ag films as well as to study the surface morphology and size distribution of Ag nanoparticles. Optical absorbance and reflectance spectra of the films were studied in the 180-1100-nm range. Air annealing effects on structure and optical properties of the DLC:Ag were investigated. Annealing temperatures were varied in the 180-400 °C range. Changes of size and shape of the Ag nanoclusters took place due to agglomeration. It was found that air annealing of DLC:Ag films can result in graphitization following destruction of the DLC matrix. Additional activation of surface-enhanced Raman scattering (SERS) effect in DLC:Ag films can be achieved by properly selecting annealing conditions. Annealing resulted in blueshift as well as significant narrowing of the plasmonic absorbance and reflectance peaks. Moreover, quadrupole surface plasmon resonance peaks appeared. Modeling of absorption spectra of the nanoclusters depending on the shape and surrounding media has been carried out.

Annealing Effects on Structure and Optical Properties of Diamond-Like Carbon Films Containing Silver

NASA Astrophysics Data System (ADS)

Meškinis, Šarūnas; Čiegis, Arvydas; Vasiliauskas, Andrius; Šlapikas, Kęstutis; Gudaitis, Rimantas; Yaremchuk, Iryna; Fitio, Volodymyr; Bobitski, Yaroslav; Tamulevičius, Sigitas

2016-03-01

In the present study, diamond-like carbon films with embedded Ag nanoparticles (DLC:Ag) were deposited by reactive magnetron sputtering. Structure of the films was investigated by Raman scattering spectroscopy. Atomic force microscopy was used to define thickness of DLC:Ag films as well as to study the surface morphology and size distribution of Ag nanoparticles. Optical absorbance and reflectance spectra of the films were studied in the 180-1100-nm range. Air annealing effects on structure and optical properties of the DLC:Ag were investigated. Annealing temperatures were varied in the 180-400 °C range. Changes of size and shape of the Ag nanoclusters took place due to agglomeration. It was found that air annealing of DLC:Ag films can result in graphitization following destruction of the DLC matrix. Additional activation of surface-enhanced Raman scattering (SERS) effect in DLC:Ag films can be achieved by properly selecting annealing conditions. Annealing resulted in blueshift as well as significant narrowing of the plasmonic absorbance and reflectance peaks. Moreover, quadrupole surface plasmon resonance peaks appeared. Modeling of absorption spectra of the nanoclusters depending on the shape and surrounding media has been carried out.

Electrical and Optical Properties of Nanocrystalline A8ZnNb6O24 (A = Ba, Sr, Ca, Mg) Ceramics

NASA Astrophysics Data System (ADS)

John, Fergy; Thomas, Jijimon K.; Jacob, John; Solomon, Sam

2017-08-01

Nanoparticles of A8ZnNb6O24 (A = Ba, Sr, Ca, and Mg, abbreviated as BZN, SZN, CZN, and MZN) have been synthesized by an auto-igniting combustion technique and their structural and optical properties characterized. The phase purity, crystal structure, and particle size of the prepared nanopowders were examined by x-ray diffraction (XRD) analysis and transmission electron microscopy. The XRD results revealed that all the samples crystallized with hexagonal perovskite structure in space group P6 3 cm. The Fourier-transform infrared and Raman (FT-Raman) spectra of the samples were investigated in detail. The ultraviolet-visible (UV-Vis) absorption spectra of the samples were also recorded and their optical bandgap energy values calculated. The nanopowders synthesized by the combustion technique were sintered to 95% of theoretical density at temperature of 1250°C for 2 h. The surface morphology of the sintered pellets was studied by scanning electron microscopy. The photoluminescence spectra of the samples showed intense emission in the blue-green region. Complex impedance analysis was used to determine the grain and grain boundary effects on the dielectric behavior of the ceramics.

Crystal Structure, Magnetic and Optical Properties of Mn-Doped BiFeO₃ by Hydrothermal Synthesis.

PubMed

Zhang, Ning; Wei, Qinhua; Qin, Laishun; Chen, Da; Chen, Zhi; Niu, Feng; Wang, Jiangying; Huanag, Yuexiang

2017-01-01

In this paper, Mn doped BiFeO₃ were firstly synthesized by hydrothermal process. The influence of Mn doping on structural, optical and magnetic properties of BiFeO₃ was studied. The different amounts of Mn doping in BiFeO₃ were characterized by X-ray diffraction, Scanning Electron Microscope, Energy Dispersive X-ray Spectroscope, UV-Vis diffuse reflectance spectroscopy and magnetic measurements. The X-ray diffraction (XRD) patterns confirmed the formation of pure phase rhombohedral structure in BiFe(1−x) Mn (x) O₃ (x = 0.01, 0.03, 0.05, 0.07) samples. The morphologies and chemical compositions of as-prepared samples could be observed by Scanning Electron Microscope (SEM) and Energy Dispersive X-ray Spectroscope (EDS). A relative large saturated magnetization (Ms) of 0.53 emu/g for x = 0.07 sample was obtained at room temperature, which is considered to be Mn ions doping. UV-Vis diffuse reflectance spectroscopy showed strong absorption of light in the range of 200–1000 nm, indicating the optical band gap in the visible region for these samples. This implied that BiFe(1−x) Mn(x)O₃ may be a potential photocatalyst for utilizing solar energy.

Spatially and temporally resolved exciton dynamics and transport in single nanostructures and assemblies

NASA Astrophysics Data System (ADS)

Huang, Libai

2015-03-01

The frontier in solar energy conversion now lies in learning how to integrate functional entities across multiple length scales to create optimal devices. To address this new frontier, I will discuss our recent efforts on elucidating multi-scale energy transfer, migration, and dissipation processes with simultaneous femtosecond temporal resolution and nanometer spatial resolution. We have developed ultrafast microscopy that combines ultrafast spectroscopy with optical microscopy to map exciton dynamics and transport with simultaneous ultrafast time resolution and diffraction-limited spatial resolution. We have employed pump-probe transient absorption microscopy to elucidate morphology and structure dependent exciton dynamics and transport in single nanostructures and molecular assemblies. More specifically, (1) We have applied transient absorption microscopy (TAM) to probe environmental and structure dependent exciton relaxation pathways in sing-walled carbon nanotubes (SWNTs) by mapping dynamics in individual pristine SWNTs with known structures. (2) We have systematically measured and modeled the optical properties of the Frenkel excitons in self-assembled porphyrin tubular aggregates that represent an analog to natural photosynthetic antennae. Using a combination of ultrafast optical microscopy and stochastic exciton modeling, we address exciton transport and relaxation pathways, especially those related to disorder.

Structural, Optical, Electrical and Photoelectrical Properties of 2-Amino-4-(5-bromothiophen-2-yl)-5,6-dihydro-6-methyl-5-oxo-4 H-pyrano[3,2-c] quinoline-3-carbonitrile Films

NASA Astrophysics Data System (ADS)

Mansour, A. M.; El-Taweel, F. M. A.; Abu El-Enein, R. A. N.; El-Menyawy, E. M.

2017-12-01

2-Amino-4-(5-bromothiophen-2-yl)-5,6-dihydro-6-methyl-5-oxo-4 H-pyrano[3,2-c] quinoline-3-carbonitrile (ABDQC) powder was synthesized and showed thermal stability up to 535 K. ABDQC films were successfully prepared using thermal evaporation. X-ray diffraction showed that the prepared ABDQC powder had a polycrystalline structure, whereas the deposited film had an amorphous structure. The surface morphology of the films was characterized by using a transmission electron microscope. Optical absorption properties of ABDQC films were investigated by spectrophotometric measurements of the transmittance and reflectance in the wavelength range 200-2500 nm. The films were found to have indirect allowed optical band gap of 2.5 eV. Current-voltage characteristics of Au/ABDQC/ p-Si/Al were measured at different temperatures (300-420 K) in which the temperature dependence of the diode parameters has been discussed. Under illumination, the device showed open-circuit voltage and short-circuit current of 0.09 V and 3.26 × 10-4 A, respectively.

A new fabrication technique for complex refractive micro-optical systems

NASA Astrophysics Data System (ADS)

Tormen, Massimo; Carpentiero, Alessandro; Ferrari, Enrico; Cabrini, Stefano; Cojoc, Dan; Di Fabrizio, Enzo

2006-01-01

We present a new method that allows to fabricate structures with tightly controlled three-dimensional profiles in the 10 nm to 100 μm scale range. This consists of a sequence of lithographic steps such as Electron Beam (EB) or Focused Ion Beam (FIB) lithography, alternated with isotropic wet etching processes performed on a quartz substrate. Morphological characterization by SEM and AFM shows that 3D structures with very accurate shape control and nanometer scale surface roughness can be realized. Quartz templates have been employed as complex system of micromirrors after metal coating of the patterned surface or used as stamps in nanoimprint, hot embossing or casting processes to shape complex plastic elements. Compared to other 3D micro and nanostructuring methods, in which a hard material is directly "sculptured" by energetic beams, our technique requires a much less intensive use of expensive lithographic equipments, for comparable volumes of structured material, resulting in dramatic increase of throughput. Refractive micro-optical elements have been fabricated and characterized in transmission and reflection modes with white and monochromatic light. The elements produce a distribution of sharp focal spots and lines in the three dimensional space, opening the route for applications of image reconstruction based on refractive optics.

Structural and optical properties of CuS thin films deposited by Thermal co-evaporation

NASA Astrophysics Data System (ADS)

Sahoo, A. K.; Mohanta, P.; Bhattacharyya, A. S.

2015-02-01

Copper sulfide (CuS) thin films with thickness 100, 150 and 200 nm have been deposited on glass substrates by thermal co-evaporation of Copper and Sulphur. The effect of CuS film thickness on the structural and optical properties have investigated and discussed. Structural and optical investigations of the films were carried out by X-ray diffraction, atomic force microscopy, high-resolution transmission electron microscopy and UV spectroscopy. XRD and selected area electron diffraction conforms that polycrystalline in nature with hexagonal crystal structure. AFM studies revealed a smooth surface morphology with root mean-square roughness values increases from 24 nm to 42 nm as the film thickness increase from 100 nm to 200 nm. AFM image showed that grain size increases with thickness of film increases and good agreement with the calculated from full width half maximum of the X-ray diffraction peak using Scherrer's formula and Williamson-Hall plot. The absorbance of the thin films were absorbed decreases with wavelength through UV-visible regions but showed a increasing in the near-infrared regions. The reflectance spectra also showed lower reflectance peak (25% to 32%) in visible region and high reflectance peak (49 % to 54 %) in near-infrared region. These high absorbance films made them for photo-thermal conversion of solar energy.

Tuning the surface morphology of aluminium doped zinc oxide thin films by arrayed nanorods through chemical growth process

NASA Astrophysics Data System (ADS)

Devasia, Sebin; Anila, E. I.

2018-04-01

Here we report the growth and characterization of chemically grown aluminium doped zinc oxide nanorods on seed layers. The seed layers were prepared by chemical spray pyrolysis which acted as the growth centers. The growth duration of nanorods were varied from 3h to 12h in steps of 3h. Further, investigations on their structural, morphological, electrical and optical properties. The SEM images confirmed the hexagonal shaped nanorod arrays grown on the seed layers. Later, the x-ray diffraction measurements revealed the pure zinc oxide phase of the samples. Photoluminescence and photoconductivity studies were carried out to analyze the potential of its optoelectronic properties.