WorldWideScience

Sample records for optical property enhancement

  1. Enhancement of nonlinear optical properties of compounds of silica ...

    Indian Academy of Sciences (India)

    Enhancement of nonlinear optical properties of compounds of silica glass and metallic nanoparticle. A GHARAATI1,∗ and A KAMALDAR1,2. 1Department of Physics, Payame Noor University, P.O. Box 19395-3697, Tehran, Iran. 2Department of Education 1, Shiraz, Iran. ∗. Corresponding author. E-mail: agharaati@pnu.ac.

  2. Enhancement of nonlinear optical properties of compounds of silica

    Indian Academy of Sciences (India)

    The aim of this paper is to introduce a method for enhancing the nonlinear optical properties in silica glass by using metallic nanoparticles. First, the T-matrix method is developed to calculate the effective dielectric constant for the compound of silica glass and metallic nanoparticles, both of which possess nonlinear dielectric ...

  3. Nitrogen doped germania glasses with enhanced optical and mechanical properties

    DEFF Research Database (Denmark)

    Storgaard-Larsen, Torben; Poulsen, Christian; Leistiko, Otto

    1997-01-01

    A new type of ultraviolet photosensitive germanium doped glass has been developed for use in the fabrication of optical waveguide structures. By adding ammonia to the source gases during a plasma enhanced chemical vapor deposition of these glasses, ultraviolet induced refractive index changes of ...

  4. Field-enhanced nonlinear optical properties of organic nanofibers

    DEFF Research Database (Denmark)

    Kostiučenko, Oksana; Fiutowski, Jacek; Brewer, Jonathan R.

    2014-01-01

    Second harmonic generation in nonlinearly optically active organic nanofibers, generated via self-assembled surface growth from nonsymmetrically functionalized para-quarterphenylene (CNHP4) molecules, has been investigated. After the growth on mica templates, nanofibers have been transferred onto...

  5. Enhancement of optical properties of InAs quantum dots grown by using periodic arsine interruption

    International Nuclear Information System (INIS)

    Kim, Jungsub; Yang, Changjae; Sim, Uk; Lee, Jaeyel; Yoon, Euijoon; Lee, Youngsoo

    2009-01-01

    We investigated the morphological and optical properties of InAs quantum dots (QDs) grown by using periodic arsine interruption (PAI) and compared them with QDs grown conventionally. In the conventional growth, the formation of large islands was observed, which suppresses the nucleation and growth of QDs. Furthermore, the growth of capping layers was significantly degraded by these large islands. On the other hand, in the PAI growth, the formation of large islands was completely suppressed, resulting in the increase of the density and aspect ratio of QDs and the uniform growth of capping layers. As a result of photoluminescence (PL) measurements, we found that the emission efficiency was enhanced and the full-width-half-maximum was reduced to 32 meV. The temperature dependence of these optical properties also revealed the enhancement of the uniformity of QDs grown by the PAI method.

  6. Anisotropic Effective Mass, Optical Property, and Enhanced Band Gap in BN/Phosphorene/BN Heterostructures.

    Science.gov (United States)

    Hu, Tao; Hong, Jisang

    2015-10-28

    Phosphorene is receiving great research interests because of its peculiar physical properties. Nonetheless, the phosphorus has a trouble of degradation due to oxidation. Hereby, we propose that the electrical and optical anisotropic properties can be preserved by encapsulating into hexagonal boron nitride (h-BN). We found that the h-BN contributed to enhancing the band gap of the phosphorene layer. Comparing the band gap of the pristine phosphorene layer, the band gap of the phosphorene/BN(1ML) system was enhanced by 0.15 eV. It was further enhanced by 0.31 eV in the BN(1ML)/phosphorene/BN(1ML) trilayer structure. However, the band gap was not further enhanced when we increased the thickness of the h-BN layers even up to 4 MLs. Interestingly, the anisotropic effective mass and optical property were still preserved in BN/phosphorene/BN heterostructures. Overall, we predict that the capping of phosphorene by the h-BN layers can be an excellent solution to protect the intrinsic properties of the phosphorene.

  7. Defect enhanced optic and electro-optic properties of lead zirconate titanate thin films

    Directory of Open Access Journals (Sweden)

    M. M. Zhu

    2011-12-01

    Full Text Available Pb(Zr1-xTixO3 (PZT thin films near phase morphotropic phase boundary were deposited on (Pb0.86La0.14TiO3-coated glass by radio frequency sputtering. A retrieved analysis shows that the lattice parameters of the as-grown PZT thin films were similar to that of monoclinic PZT structure. Moreover, the PZT thin films possessed refractive index as high as 2.504 in TE model and 2.431 in TM model. The as-grown PZT thin film had one strong absorption peak at 632.6 nm, which attributed to lead deficiency by quantitative XPS analysis. From the attractive properties achieved, electro-optic and photovoltaic characteristic of the films were carried out.

  8. Polyaniline/carbon nanotube/CdS quantum dot composites with enhanced optical and electrical properties

    Energy Technology Data Exchange (ETDEWEB)

    Goswami, Mrinmoy [Department of Physics, National Institute of Technology, Durgapur, 713209 (India); Ghosh, Ranajit, E-mail: ghosh.ranajit@gmail.com [CSIR-Central Mechanical Engineering Research Institute, Durgapur, 713209 (India); Maruyama, Takahiro [Department of Applied Chemistry, Meijo University, Nagoya, 4688502 (Japan); Meikap, Ajit Kumar [Department of Physics, National Institute of Technology, Durgapur, 713209 (India)

    2016-02-28

    Graphical abstract: - Highlights: • A new kind of polyaniline/carbon nanotube/CdS quantum dot composites have been synthesized via in-situ polymerization of aniline monomer. • A degree of increase in conductivity. • Size-dependent optical properties of CdS quantum dots have been observed. - Abstract: A new kind of polyaniline/carbon nanotube/CdS quantum dot composites have been developed via in-situ polymerization of aniline monomer in the presence of dispersed CdS quantum dots (size: 2.7–4.8 nm) and multi-walled carbon nanotubes (CNT), which exhibits enhanced optical and electrical properties. The existences of 1st order, 2nd order, and 3rd order longitudinal optical phonon modes, strongly indicate the high quality of synthesized CdS quantum dots. The occurrence of red shift of free exciton energy in photoluminescence is due to size dependent quantum confinement effect of CdS. The conductivity of the composites (for example PANI/CNT/CdS (2 wt.% CdS)) is increased by about 7 of magnitude compared to that of pure PANI indicating a charge transfer between CNT and polymer via CdS quantum dots. This advanced material has a great potential for high-performance of electro-optical applications.

  9. Plasmon mediated enhancement and tuning of optical emission properties of two dimensional graphitic carbon nitride nanosheets.

    Science.gov (United States)

    Bayan, Sayan; Gogurla, Narendar; Midya, Anupam; Singha, Achintya; Ray, Samit K

    2017-12-01

    We demonstrate surface plasmon induced enhancement and tunablilty in optical emission properties of two dimensional graphitic carbon nitride (g-C 3 N 4 ) nanosheets through the attachment of gold (Au) nanoparticles. Raman spectroscopy has revealed surface enhanced Raman scattering that arises due to the combined effect of the charge transfer process and localized surface plasmon induced enhancement in electromagnetic field, both occurring at the nanoparticle-nanosheet interface. Photoluminescence studies suggest that at an optimal concentration of nanoparticles, the emission intensity can be enhanced, which is maximum within the 500-525 nm region. Further, the fabricated electroluminescent devices reveal that the emission feature can be tuned from bluish-green to red (∼160 nm shift) upon attaching Au nanoparticles. We propose that the π*→π transition in g-C 3 N 4 can trigger surface plasmon oscillation in Au, which subsequently increases the excitation process in the nanosheets and results in enhanced emission in the green region of the photoluminescence spectrum. On the other hand, electroluminescence of g-C 3 N 4 can induce plasmon oscillation more efficiently and thus can lead to red emission from Au nanoparticles through the radiative damping of particle plasmons. The influence of nanoparticle size and coverage on the emission properties of two dimensional g-C 3 N 4 , nanosheets has also been studied in detail.

  10. Polyaniline/carbon nanotube/CdS quantum dot composites with enhanced optical and electrical properties

    Science.gov (United States)

    Goswami, Mrinmoy; Ghosh, Ranajit; Maruyama, Takahiro; Meikap, Ajit Kumar

    2016-02-01

    A new kind of polyaniline/carbon nanotube/CdS quantum dot composites have been developed via in-situ polymerization of aniline monomer in the presence of dispersed CdS quantum dots (size: 2.7-4.8 nm) and multi-walled carbon nanotubes (CNT), which exhibits enhanced optical and electrical properties. The existences of 1st order, 2nd order, and 3rd order longitudinal optical phonon modes, strongly indicate the high quality of synthesized CdS quantum dots. The occurrence of red shift of free exciton energy in photoluminescence is due to size dependent quantum confinement effect of CdS. The conductivity of the composites (for example PANI/CNT/CdS (2 wt.% CdS)) is increased by about 7 of magnitude compared to that of pure PANI indicating a charge transfer between CNT and polymer via CdS quantum dots. This advanced material has a great potential for high-performance of electro-optical applications.

  11. Rational Design of Branched Nanoporous Gold Nanoshells with Enhanced Physico-Optical Properties for Optical Imaging and Cancer Therapy.

    Science.gov (United States)

    Song, Jibin; Yang, Xiangyu; Yang, Zhen; Lin, Lisen; Liu, Yijing; Zhou, Zijian; Shen, Zheyu; Yu, Guocan; Dai, Yunlu; Jacobson, Orit; Munasinghe, Jeeva; Yung, Bryant; Teng, Gao-Jun; Chen, Xiaoyuan

    2017-06-27

    Reported procedures on the synthesis of gold nanoshells with smooth surfaces have merely demonstrated efficient control of shell thickness and particle size, yet no branch and nanoporous features on the nanoshell have been implemented to date. Herein, we demonstrate the ability to control the roughness and nanoscale porosity of gold nanoshells by using redox-active polymer poly(vinylphenol)-b-(styrene) nanoparticles as reducing agent and template. The porosity and size of the branches on this branched nanoporous gold nanoshell (BAuNSP) material can be facilely adjusted by control of the reaction speed or the reaction time between the redox-active polymer nanoparticles and gold ions (Au 3+ ). Due to the strong reduction ability of the redox-active polymer, the yield of BAuNSP was virtually 100%. By taking advantage of the sharp branches and nanoporous features, BAuNSP exhibited greatly enhanced physico-optical properties, including photothermal effect, surface-enhanced Raman scattering (SERS), and photoacoustic (PA) signals. The photothermal conversion efficiency can reach as high as 75.5%, which is greater than most gold nanocrystals. Furthermore, the nanoporous nature of the shells allows for effective drug loading and controlled drug release. The thermoresponsive polymer coated on the BAuNSP surface serves as a gate keeper, governing the drug release behavior through photothermal heating. Positron emission tomography imaging demonstrated a high passive tumor accumulation of 64 Cu-labeled BAuNSP. The strong SERS signal generated by the SERS-active BAuNSP in vivo, accompanied by enhanced PA signals in the tumor region, provide significant tumor information, including size, morphology, position, and boundaries between tumor and healthy tissues. In vivo tumor therapy experiments demonstrated a highly synergistic chemo-photothermal therapy effect of drug-loaded BAuNSPs, guided by three modes of optical imaging.

  12. Enhanced nonlinear optical absorption and optical limiting properties of superparamagnetic spinel zinc ferrite decorated reduced graphene oxide nanostructures

    International Nuclear Information System (INIS)

    Saravanan, M.; Sabari Girisun, T.C.

    2017-01-01

    Highlights: • Nanospindle and nanosphere ZnFe_2O_4 were decorated upon GO by hydrothermal method. • All the samples show superparamagnetism with almost zero coercivity and remanence. • The observed nonlinearity arises due to effective two photon absorption process. • Tuning of NLO behavior with variation in amount of ZnFe_2O_4 upon GO were achieved. • ZnFe_2O_4-(15 wt%)GO show higher NLO coefficients and superior limiting actions. - Abstract: Nonlinear absorption and optical limiting properties of ZnFe_2O_4-rGO magnetic nanostructures was investigated by the Z-scan technique using Q-switched Nd:YAG laser (5 ns, 532 nm, 10 Hz) as an excitation source. Excited state absorption was the dominant process responsible for the observed nonlinearity in ZnFe_2O_4 decorated rGO which arises due to photo-generated charge carriers in the conduction band of zinc ferrite and increases in defects at the surface of rGO due to the incorporation of ZnFe_2O_4. The magnitude of the nonlinear absorption co-efficient was found to be in the order of 10"−"1"0 m/W. A noteworthy enhancement in the third-order NLO properties in ZnFe_2O_4-(15 wt%) rGO with those of individual counter parts and well known graphene composites was reported. Role of induced defects states (sp"3) arising from the functionalization of rGO in the enhancement of NLO response was explained through Raman studies. Earlier incorporation and distribution of ZnFe_2O_4 upon GO through one-step hydrothermal method was analyzed by XRD and FTIR. Formation of (nanospheres/nanospindles) ZnFe_2O_4 along with reduction of graphene oxide was confirmed through TEM analysis. VSM studies showed zinc ferrite decorated rGO posseses superparamagnetic behavior. The tuning of nonlinear optical and magnetic behavior with variation in the content of spinel ferrites upon reduced graphene oxide provides an easy way to attain tunable properties which are exceedingly required in both optoelectronics and photothermal therapy

  13. Enhanced nonlinear optical absorption and optical limiting properties of superparamagnetic spinel zinc ferrite decorated reduced graphene oxide nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Saravanan, M.; Sabari Girisun, T.C., E-mail: sabarigirisun@bdu.ac.in

    2017-01-15

    Highlights: • Nanospindle and nanosphere ZnFe{sub 2}O{sub 4} were decorated upon GO by hydrothermal method. • All the samples show superparamagnetism with almost zero coercivity and remanence. • The observed nonlinearity arises due to effective two photon absorption process. • Tuning of NLO behavior with variation in amount of ZnFe{sub 2}O{sub 4} upon GO were achieved. • ZnFe{sub 2}O{sub 4}-(15 wt%)GO show higher NLO coefficients and superior limiting actions. - Abstract: Nonlinear absorption and optical limiting properties of ZnFe{sub 2}O{sub 4}-rGO magnetic nanostructures was investigated by the Z-scan technique using Q-switched Nd:YAG laser (5 ns, 532 nm, 10 Hz) as an excitation source. Excited state absorption was the dominant process responsible for the observed nonlinearity in ZnFe{sub 2}O{sub 4} decorated rGO which arises due to photo-generated charge carriers in the conduction band of zinc ferrite and increases in defects at the surface of rGO due to the incorporation of ZnFe{sub 2}O{sub 4}. The magnitude of the nonlinear absorption co-efficient was found to be in the order of 10{sup −10} m/W. A noteworthy enhancement in the third-order NLO properties in ZnFe{sub 2}O{sub 4}-(15 wt%) rGO with those of individual counter parts and well known graphene composites was reported. Role of induced defects states (sp{sup 3}) arising from the functionalization of rGO in the enhancement of NLO response was explained through Raman studies. Earlier incorporation and distribution of ZnFe{sub 2}O{sub 4} upon GO through one-step hydrothermal method was analyzed by XRD and FTIR. Formation of (nanospheres/nanospindles) ZnFe{sub 2}O{sub 4} along with reduction of graphene oxide was confirmed through TEM analysis. VSM studies showed zinc ferrite decorated rGO posseses superparamagnetic behavior. The tuning of nonlinear optical and magnetic behavior with variation in the content of spinel ferrites upon reduced graphene oxide provides an easy way to attain tunable

  14. Enhanced electrical and optical properties of CdS:Na thin films by photochemical deposition

    Science.gov (United States)

    Kumar, V. Nirmal; Suriakarthick, R.; Gopalakrishnan, R.; Hayakawa, Y.

    2017-06-01

    CdS:Na thin film was deposited on a glass substrate by photochemical deposition from aqueous solution contained CdSO4.5H2O and Na2S2O3 as cation and anion sources, respectively. The anion source Na2S2O3 served as Na dopant source. The deposited film exhibited cubic phase of CdS and incorporation of Na was revealed from X-ray diffraction study. The incorporation of Na in CdS changed the surface morphology from spherical to nano rods. CdS:Na thin film showed blue shift in its absorption spectrum which was more desirable for transmitting higher energy photons (visible region) in thin film solar cells. The Raman analysis confirmed 1 LO and 2 LO process at 297 and 593 cm-1, respectively. The carrier concentration of CdS increased with the inclusion of Na and its resistivity value decreased. Both the electrical and optical properties of CdS were enhanced in CdS:Na thin films which was desirable as a window layer material for photovoltaic application.

  15. Nanostructure and optical properties of CeO{sub 2} thin films obtained by plasma-enhanced chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Barreca, D.; Bruno, G.; Gasparotto, A.; Losurdo, M.; Tondello, E

    2003-12-15

    In the present study, Spectroscopic Ellipsometry (SE) is used to investigate the interrelations between nanostructure and optical properties of CeO{sub 2} thin films deposited by Plasma-Enhanced Chemical Vapor Deposition (PE-CVD). The layers were synthesized in Ar and Ar-O{sub 2} plasmas on Si(100) substrates at temperatures lower than 300 deg. C. Both the real and imaginary parts of the complex dielectric functions and, subsequently, the optical constants of the films are derived up to 6.0 eV photon energy. Particular attention is devoted to the influence of synthesis conditions and sample properties on the optical response, taking into account the effects of surface roughness and SiO{sub 2} interface layer on Si.

  16. Enhanced optical and electrical properties of Ni inserted ITO/Ni/AZO tri-layer structure for photoelectric applications

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, M. Melvin David; Kim, Hyunki [Department of Electrical Engineering, Incheon National University, Incheon 406772 (Korea, Republic of); Park, Yun Chang [Measurement and Analysis Division, National Nanofab Center (NNFC), Daejeon 305-806 (Korea, Republic of); Kim, Joondong, E-mail: joonkim@incheon.ac.kr [Department of Electrical Engineering, Incheon National University, Incheon 406772 (Korea, Republic of)

    2015-05-15

    Highlights: • Ni-embedding transparent conductor effectively reduces the resistivity. • Ni insertion improves the carrier mobility and collection efficiencies. • ITO/Ni/AZO is effective to improve photo-responses compared to ITO/AZO. - Abstract: A thin Ni layer of 5 nm thickness was deposited in between indium-tin-oxide (ITO) and aluminum-doped-zinc oxide (AZO) layers of 50 nm thickness each. The Ni inserting tri-layer structure (ITO/Ni/AZO) showed lower resistivity of 5.51 × 10{sup −4} Ωcm which is nearly 20 times lesser than 97.9 × 10{sup −4} Ωcm of bilayer structure (ITO/AZO). A thin Ni layer in between ITO and AZO enhanced the carrier concentration, mobility and photoresponse behaviors so that figure of merit (FOM) value of ITO/Ni/AZO device was greater than that of ITO/AZO device. ITO/Ni/AZO structure showed improved quantum efficiencies over a broad range of wavelengths (∼350–950 nm) compared to that of ITO/AZO bilayer structure, resulting in enhanced photoresponses. These results show that the optical, electrical and photoresponse properties of ITO/AZO structure could be enhanced by inserting Ni layer of 5 nm thickness in between ITO and AZO layers.

  17. Optical properties of solids

    CERN Document Server

    Wooten, Frederick

    1972-01-01

    Optical Properties of Solids covers the important concepts of intrinsic optical properties and photoelectric emission. The book starts by providing an introduction to the fundamental optical spectra of solids. The text then discusses Maxwell's equations and the dielectric function; absorption and dispersion; and the theory of free-electron metals. The quantum mechanical theory of direct and indirect transitions between bands; the applications of dispersion relations; and the derivation of an expression for the dielectric function in the self-consistent field approximation are also encompassed.

  18. Optical adhesive property study

    Energy Technology Data Exchange (ETDEWEB)

    Sundvold, P.D.

    1996-01-01

    Tests were performed to characterize the mechanical and thermal properties of selected optical adhesives to identify the most likely candidate which could survive the operating environment of the Direct Optical Initiation (DOI) program. The DOI system consists of a high power laser and an optical module used to split the beam into a number of channels to initiate the system. The DOI requirements are for a high shock environment which current military optical systems do not operate. Five candidate adhesives were selected and evaluated using standardized test methods to determine the adhesives` physical properties. EC2216, manufactured by 3M, was selected as the baseline candidate adhesive based on the test results of the physical properties.

  19. Enhanced structural and optical properties of the polyaniline-calcium tungstate (PANI-CaWO4 nanocomposite for electronics applications

    Science.gov (United States)

    Sabu, N. Aloysius; Francis, Xavier; Anjaly, Jose; Sankararaman, S.; Varghese, Thomas

    2017-06-01

    In this article, we report the synthesis and characterization of polyaniline-calcium tungstate nanocomposite, a novel material for potential applications. The PANI-CaWO4 nanocomposite was prepared by in situ oxidative polymerization of aniline in the presence of CaWO4 nanoparticles dispersed in ethanol. Investigations using X-ray diffraction, Fourier-transformed infrared spectroscopy, UV-visible, photoluminescence and Raman spectroscopy confirmed the formation of the nanocomposite of PANI with CaWO4 nanoparticles. Scanning electron microscopy revealed almost uniform distribution of CaWO4 nanoparticles in the polyaniline matrix. These studies also confirmed electronic structure modification as a result of incorporating CaWO4 nanoparticles in PANI. Composite formation resulted in large decrease in the optical band gap and enhanced photoluminescence. The augmented structural, optical and photoluminescence properties of the PANI-CaWO4 nanocomposite can be used to explore potential applications in micro- and optoelectronics. This is the first report presenting synthesis and characterization of the PANI-CaWO4 nanocomposite.

  20. Quantum enhanced optical sensing

    DEFF Research Database (Denmark)

    Schäfermeier, Clemens

    light source was designed and built from scratch, which achieved a noise suppression of −8 dB at an optical pump power of 40mW. The generated squeezed light was first used to demonstrate how Gaussian states and detection can beat the shot noise limit and Rayleigh criterion in phase measurements...... or demanding detection techniques. A second experiment combined squeezed light and feedback control to cool an optomechanical system. This proof-of-principle study is the first reported squeezing enhanced optomechanical cooling experiment. Despite losses of more than 50% (a resulting noise suppression of −2 d...... signals to overcome e.g. technical detection limitations. Amplified communication channels were characterised by applying the measure of mutual information I, as it offers strict bounds on the maximum achievable performance, which enabled a fair comparison between different applications scenarios...

  1. Optical properties of nanoparticles

    DEFF Research Database (Denmark)

    Bendix, Pól Martin

    2015-01-01

    At the NBI I am involved in projects relating to optical properties of metallic nanoparticles in particular with respect to plasmonic heating with direct applications to photothermal cancer therapy. For this purpose we have developed heating assays that can be used to measure the heating of any...... nanoscopic heat source like an irradiated nanoparticle...

  2. Efficient Donor Impurities in ZnO Nanorods by Polyethylene Glycol for Enhanced Optical and Glutamate Sensing Properties

    Directory of Open Access Journals (Sweden)

    Sami Elhag

    2016-02-01

    Full Text Available In this paper, we show that the possibility of using polyethylene glycol (EG as a hydrogen source and it is used to assist the hydrothermal synthesis of ZnO nanorods (ZNRs. EG doping in ZNRs has been found to significantly improve their optical and chemical sensing characteristics toward glutamate. The EG was found to have no role on the structural properties of the ZNRs. However, the x-ray photoelectron spectroscopy (XPS suggests that the EG could induce donor impurities effect in ZnO. Photoluminescence (PL and UV-Vis. spectra demonstrated this doping effect. Mott-Schottky analysis at the ZNRs/electrolyte interface was used to investigate the charge density for the doped ZNRs and showed comparable dependence on the used amount of EG. Moreover, the doped ZNRs were used in potentiometric measurements for glutamate for a range from 10−6 M to 10−3 M and the potential response of the sensor electrode was linear with a slope of 91.15 mV/decade. The wide range and high sensitivity of the modified ZNRs based glutamate biosensor is attributed to the doping effect on the ZNRs that is dictated by the EG along with the high surface area-to-volume ratio. The findings in the present study suggest new avenues to control the growth of n-ZnO nanostructures and enhance the performance of their sensing devices.

  3. Efficient Donor Impurities in ZnO Nanorods by Polyethylene Glycol for Enhanced Optical and Glutamate Sensing Properties.

    Science.gov (United States)

    Elhag, Sami; Khun, Kimleang; Khranovskyy, Volodymyr; Liu, Xianjie; Willander, Magnus; Nur, Omer

    2016-02-06

    In this paper, we show that the possibility of using polyethylene glycol (EG) as a hydrogen source and it is used to assist the hydrothermal synthesis of ZnO nanorods (ZNRs). EG doping in ZNRs has been found to significantly improve their optical and chemical sensing characteristics toward glutamate. The EG was found to have no role on the structural properties of the ZNRs. However, the x-ray photoelectron spectroscopy (XPS) suggests that the EG could induce donor impurities effect in ZnO. Photoluminescence (PL) and UV-Vis. spectra demonstrated this doping effect. Mott-Schottky analysis at the ZNRs/electrolyte interface was used to investigate the charge density for the doped ZNRs and showed comparable dependence on the used amount of EG. Moreover, the doped ZNRs were used in potentiometric measurements for glutamate for a range from 10(-6) M to 10(-3) M and the potential response of the sensor electrode was linear with a slope of 91.15 mV/decade. The wide range and high sensitivity of the modified ZNRs based glutamate biosensor is attributed to the doping effect on the ZNRs that is dictated by the EG along with the high surface area-to-volume ratio. The findings in the present study suggest new avenues to control the growth of n-ZnO nanostructures and enhance the performance of their sensing devices.

  4. The fabrication and enhanced nonlinear optical properties of electrostatic self-assembled film containing water-soluble chiral polymers

    Energy Technology Data Exchange (ETDEWEB)

    Ouyang Qiuyun, E-mail: qyouyang7823@yahoo.cn [College of Science, Harbin Engineering University, Harbin 150001 (China); Chen Yujin; Li Chunyan [College of Science, Harbin Engineering University, Harbin 150001 (China)

    2012-05-15

    Highlights: Black-Right-Pointing-Pointer The ultra-thin film containing the chiral PPV and oligo-thiophene derivatives was fabricated. Black-Right-Pointing-Pointer The third-order NLO properties were studied of the ultra-thin film. Black-Right-Pointing-Pointer The reverse saturable absorption and self-defocusing were observed. Black-Right-Pointing-Pointer The nonlinear optical mechanism was discussed. - Abstract: An ultra-thin film containing a water-soluble chiral PPV derivative and oligo-thiophene derivative was fabricated through the electrostatic self-assembly technique. The PPV and thiophene derivatives are poly{l_brace}(2,5-bis(3-bromotrimethylammoniopropoxy)-phenylene-1,4-divinylene) -alt-1,4-(2,5-bis((3-hydroxy-2-(S)-methyl)propoxy)phenylenevinylene) (BHP-PPV) and 4 Prime ,3 Double-Prime -dipentyl-5,2 Prime :5 Prime ,2 Double-Prime :5 Double-Prime ,2 Double-Prime Prime -quaterthiophene-2,5 Double-Prime Prime -dicarboxylic acid (QTDA), respectively. The circular dichroism (CD) spectrum of BHP-PPV cast film on quartz substrate proved the chirality of BHP-PPV. The UV-vis spectra showed a continuous deposition process of BHP-PPV and QTDA. The film structure was characterized by small angle X-ray diffraction (XRD) measurement and atomic force microscopy (AFM) images. The nonlinear optical (NLO) properties of BHP-PPV/QTDA ultra-thin film with different number of bilayers were investigated by the Z-scan technique with 8 ns laser pulse at 532 nm. The Z-scan experimental data were analyzed with the double-sided film Z-scan theory. The BHP-PPV/QTDA film exhibits enhanced reverse saturable absorption (RSA) and self-defocusing effects, which may be attributed to the conjugated strength, chirality and well-ordered film structure. The chirality may lead to the RSA of BHP-PPV/QTDA film contrary to the SA of the other electrostatic self-assembled films without chiral units. The self-defocusing effect should be due to the thermal effect.

  5. Enhanced radiation resistant fiber optics

    International Nuclear Information System (INIS)

    Lyons, P.B.; Looney, L.D.

    1993-01-01

    A process for producing an optical fiber having enhanced radiation resistance is provided, the process including maintaining an optical fiber within a hydrogen-containing atmosphere for sufficient time to yield a hydrogen-permeated optical fiber having an elevated internal hydrogen concentration, and irradiating the hydrogen-permeated optical fiber at a time while the optical fiber has an elevated internal hydrogen concentration with a source of ionizing radiation. The radiation source is typically a cobalt-60 source and the fiber is pre-irradiated with a dose level up to about 1000 kilorads of radiation. 4 figures

  6. Enhanced radiation resistant fiber optics

    Science.gov (United States)

    Lyons, P.B.; Looney, L.D.

    1993-11-30

    A process for producing an optical fiber having enhanced radiation resistance is provided, the process including maintaining an optical fiber within a hydrogen-containing atmosphere for sufficient time to yield a hydrogen-permeated optical fiber having an elevated internal hydrogen concentration, and irradiating the hydrogen-permeated optical fiber at a time while the optical fiber has an elevated internal hydrogen concentration with a source of ionizing radiation. The radiation source is typically a cobalt-60 source and the fiber is pre-irradiated with a dose level up to about 1000 kilorads of radiation. 4 figures.

  7. Enhancement of the optical and electrical properties of ITO thin films deposited by electron beam evaporation technique

    Science.gov (United States)

    Ali, H. M.; Mohamed, H. A.; Mohamed, S. H.

    2005-08-01

    Indium tin oxide (ITO) is widely utilized in numerous industrial applications due to its unique combined properties of transparency to visible light and electrical conductivity. ITO films were deposited on glass substrates by an electron beam evaporation technique at room temperature from bulk samples, with different thicknesses. The film with 1500 Å thick was selected to perform annealing in the temperature range of 200 400 °C and annealing for varying times from 15 to 120 min at 400 °C. The X-ray diffraction of the films was analyzed in order to investigate its dependence on thickness, and annealing. Electrical and optical measurements were also carried out. Transmittance, optical energy gap, refractive index, carrier concentration, thermal emissivity and resistivity were investigated. It was found that the as-deposited films with different thicknesses were highly absorbing and have relatively poor electrical properties. The films become opaque with increasing the film thickness. After thermal annealing, the resistance decreases and a simultaneous variation in the optical transmission occurs. A transmittance value of 85.5% in the IR region and 82% in the visible region of the spectrum and a resistivity of 2.8 × 10-4 Ω Cm were obtained at annealing temperature of 400 °C for 120 min.

  8. Enhanced optical and electrical properties of Y-doped ZnO nanoparticles having different Y concentrations

    Science.gov (United States)

    Üzar, Neslihan

    2018-04-01

    In this study, undoped ZnO and yttrium (Y)-doped ZnO (YZO) nanoparticles having different Y dopant concentrations (Zn1- x Y x O; x = 0.005, 0.01, 0.015, 0.02) were successfully synthesized by sol-gel dip-coating method. Structural characterizations of the obtained samples were examined with scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) analyses. SEM analysis shows that the synthesized nanoparticles are mostly dot-like structures. The sizes of nanostructures decrease with increasing Y-doping concentration up to 2 mol % Y and XRD results show that all of samples have wurtzite hexagonal structure of ZnO with (002) c-plane orientation. According to EDS results pure YZO samples are obtained. Optical transmittances of all samples were investigated in the range of 350-750 nm at room temperature. The average optical transmittances of YZO samples in the visible region are approximately over 90%, but the transmittance starts to decrease for Zn0.98Y0.02O sample. Also, it was observed that the optical transmittances of Y-doped samples are higher than that of undoped ZnO. The electrical properties of YZO samples were obtained by resistance measurements at room temperature. The resistivity of samples was found to be 2.25 × 10-3, 1.43 × 10-3, 7.8 × 10-3, and 1.3 × 10-3 Ω-cm for Zn0.995Y0.005O, Zn0.99Y0.01O, Zn0.985Y0.015O and Zn0.98Y0.02O, respectively. All these results show that surface, structural, electrical and optical properties of ZnO samples can be improved with doping Y up to 2 mol % concentrations.

  9. Electronic structures and enhanced optical properties of blue phosphorene/transition metal dichalcogenides van der Waals heterostructures

    Science.gov (United States)

    Peng, Qiong; Wang, Zhenyu; Sa, Baisheng; Wu, Bo; Sun, Zhimei

    2016-01-01

    As a fast emerging topic, van der Waals (vdW) heterostructures have been proposed to modify two-dimensional layered materials with desired properties, thus greatly extending the applications of these materials. In this work, the stacking characteristics, electronic structures, band edge alignments, charge density distributions and optical properties of blue phosphorene/transition metal dichalcogenides (BlueP/TMDs) vdW heterostructures were systematically studied based on vdW corrected density functional theory. Interestingly, the valence band maximum and conduction band minimum are located in different parts of BlueP/MoSe2, BlueP/WS2 and BlueP/WSe2 heterostructures. The MoSe2, WS2 or WSe2 layer can be used as the electron donor and the BlueP layer can be used as the electron acceptor. We further found that the optical properties under visible-light irradiation of BlueP/TMDs vdW heterostructures are significantly improved. In particular, the predicted upper limit energy conversion efficiencies of BlueP/MoS2 and BlueP/MoSe2 heterostructures reach as large as 1.16% and 0.98%, respectively, suggesting their potential applications in efficient thin-film solar cells and optoelectronic devices. PMID:27553787

  10. Electronic structures and enhanced optical properties of blue phosphorene/transition metal dichalcogenides van der Waals heterostructures.

    Science.gov (United States)

    Peng, Qiong; Wang, Zhenyu; Sa, Baisheng; Wu, Bo; Sun, Zhimei

    2016-08-24

    As a fast emerging topic, van der Waals (vdW) heterostructures have been proposed to modify two-dimensional layered materials with desired properties, thus greatly extending the applications of these materials. In this work, the stacking characteristics, electronic structures, band edge alignments, charge density distributions and optical properties of blue phosphorene/transition metal dichalcogenides (BlueP/TMDs) vdW heterostructures were systematically studied based on vdW corrected density functional theory. Interestingly, the valence band maximum and conduction band minimum are located in different parts of BlueP/MoSe2, BlueP/WS2 and BlueP/WSe2 heterostructures. The MoSe2, WS2 or WSe2 layer can be used as the electron donor and the BlueP layer can be used as the electron acceptor. We further found that the optical properties under visible-light irradiation of BlueP/TMDs vdW heterostructures are significantly improved. In particular, the predicted upper limit energy conversion efficiencies of BlueP/MoS2 and BlueP/MoSe2 heterostructures reach as large as 1.16% and 0.98%, respectively, suggesting their potential applications in efficient thin-film solar cells and optoelectronic devices.

  11. Enhanced linear and nonlinear optical properties of thermally stable ZnO/poly(styrene)–poly(methyl methacrylate) nanocomposite films

    International Nuclear Information System (INIS)

    Jeeju, P.P.; Jayalekshmi, S.; Chandrasekharan, K.; Sudheesh, P.

    2013-01-01

    Highly transparent and thermally stable zinc oxide (ZnO)/poly(styrene)–poly(methyl methacrylate) (PS–PMMA) nanocomposite films have been deposited on glass substrates, from the ZnO incorporated (PS–PMMA) solutions in toluene, using spin coating technique. A chemical route at room temperature is used to synthesize the ZnO nanoparticles. Transmission electron microscope and high-resolution transmission electron microscope images show that the ZnO nanoparticles are of size around 10 nm. The composite films have been characterized by X-ray diffraction, Fourier transform infrared spectroscopy, atomic force microscopy, Ultraviolet–visible–Near Infrared (UV–vis–NIR) spectroscopy, Thermo-gravimetric analysis, photoluminescence (PL) spectroscopy and Z-scan technique. From the UV–vis–NIR spectra it is observed that the ZnO/PS–PMMA nanocomposite films with 10 wt.% ZnO content exhibit excellent shielding property in the UV region and, high transparency in the visible region. The PL spectrum of the composite films is different from that of ZnO and PS–PMMA blend and exhibits an excitonic emission peak at ∼ 375 nm. The optical absorptive nonlinearity in the nanocomposite films is investigated using open aperture Z-scan technique. The results indicate optical limiting type nonlinearity in the films due to two photon absorption. A transmittance minimum of around 0.25 has been observed in the ZnO/PS–PMMA nanocomposite films which is much lower compared to that in ZnO/PMMA and ZnO/PS nanocomposite films. The ZnO/PS–PMMA nanocomposite films also show a self-defocusing type negative nonlinear refraction in closed aperture Z-scan experiment. These nanocomposite films extend ample scope of applications as excellent optical limiters and efficient UV protectors. - Highlights: ► Transparent, ZnO/poly(styrene)–poly(methyl methacrylate) composite films are prepared. ► The nanocomposite films with 10 wt.% ZnO content exhibit good UV-shielding property.

  12. Enhanced linear and nonlinear optical properties of thermally stable ZnO/poly(styrene)–poly(methyl methacrylate) nanocomposite films

    Energy Technology Data Exchange (ETDEWEB)

    Jeeju, P.P., E-mail: jeejupp@gmail.com [Division for Research in Advanced Materials, Department of Physics, Cochin University of Science and Technology, Kochi 682 022, Kerala (India); Jayalekshmi, S., E-mail: jayalekshmi@cusat.ac.in [Division for Research in Advanced Materials, Department of Physics, Cochin University of Science and Technology, Kochi 682 022, Kerala (India); Chandrasekharan, K.; Sudheesh, P. [Department of Physics, National Institute of Technology, Calicut, Kerala (India)

    2013-03-01

    Highly transparent and thermally stable zinc oxide (ZnO)/poly(styrene)–poly(methyl methacrylate) (PS–PMMA) nanocomposite films have been deposited on glass substrates, from the ZnO incorporated (PS–PMMA) solutions in toluene, using spin coating technique. A chemical route at room temperature is used to synthesize the ZnO nanoparticles. Transmission electron microscope and high-resolution transmission electron microscope images show that the ZnO nanoparticles are of size around 10 nm. The composite films have been characterized by X-ray diffraction, Fourier transform infrared spectroscopy, atomic force microscopy, Ultraviolet–visible–Near Infrared (UV–vis–NIR) spectroscopy, Thermo-gravimetric analysis, photoluminescence (PL) spectroscopy and Z-scan technique. From the UV–vis–NIR spectra it is observed that the ZnO/PS–PMMA nanocomposite films with 10 wt.% ZnO content exhibit excellent shielding property in the UV region and, high transparency in the visible region. The PL spectrum of the composite films is different from that of ZnO and PS–PMMA blend and exhibits an excitonic emission peak at ∼ 375 nm. The optical absorptive nonlinearity in the nanocomposite films is investigated using open aperture Z-scan technique. The results indicate optical limiting type nonlinearity in the films due to two photon absorption. A transmittance minimum of around 0.25 has been observed in the ZnO/PS–PMMA nanocomposite films which is much lower compared to that in ZnO/PMMA and ZnO/PS nanocomposite films. The ZnO/PS–PMMA nanocomposite films also show a self-defocusing type negative nonlinear refraction in closed aperture Z-scan experiment. These nanocomposite films extend ample scope of applications as excellent optical limiters and efficient UV protectors. - Highlights: ► Transparent, ZnO/poly(styrene)–poly(methyl methacrylate) composite films are prepared. ► The nanocomposite films with 10 wt.% ZnO content exhibit good UV-shielding property.

  13. Enhanced Optical and Electrical Properties of TiO_2 Buffered IGZO/TiO_2 Bi-Layered Films

    International Nuclear Information System (INIS)

    Moon, Hyun-Joo; Kim, Daeil

    2016-01-01

    In and Ga doped ZnO (IGZO, 100-nm thick) thin films were deposited by radio frequency magnetron sputtering without intentional substrate heating on a bare glass substrate and a TiO_2-deposited glass substrate to determine the effect of the thickness of a thin TiO_2 buffer layer on the structural, optical, and electrical properties of the films. The thicknesses of the TiO_2 buffer layers were 5, 10 and 15 nm, respectively. As-deposited IGZO films with a 10 nm-thick TiO_2 buffer layer had an average optical transmittance of 85.0% with lower resistivity (1.83×10-2 Ω cm) than that of IGZO single layer films. The figure of merit (FOM) reached a maximum of 1.44×10-4 Ω-1 for IGZO/10 nm-thick TiO_2 bi-layered films, which is higher than the FOM of 6.85×10-5 Ω-1 for IGZO single layer films. Because a higher FOM value indicates better quality transparent conducting oxide (TCO) films, the IGZO/10 nm-thick TiO_2 bi-layered films are likely to perform better in TCO applications than IGZO single layer films.

  14. Large-scale fabrication of linear low density polyethylene/layered double hydroxides composite films with enhanced heat retention, thermal, mechanical, optical and water vapor barrier properties

    Energy Technology Data Exchange (ETDEWEB)

    Xie, Jiazhuo; Zhang, Kun; Zhao, Qinghua [College of Chemistry and Material Science, Shandong Agricultural University, 61 Daizong Street, Tai' an 271018 (China); Wang, Qingguo, E-mail: wqgyyy@126.com [College of Food Science and Engineering, Shandong Agricultural University, 61 Daizong Street, Tai' an 271018 (China); Xu, Jing, E-mail: jiaxu@sdau.edu.cn [College of Chemistry and Material Science, Shandong Agricultural University, 61 Daizong Street, Tai' an 271018 (China)

    2016-11-15

    Novel LDH intercalated with organic aliphatic long-chain anion was large-scale synthesized innovatively by high-energy ball milling in one pot. The linear low density polyethylene (LLDPE)/layered double hydroxides (LDH) composite films with enhanced heat retention, thermal, mechanical, optical and water vapor barrier properties were fabricated by melt blending and blowing process. FT IR, XRD, SEM results show that LDH particles were dispersed uniformly in the LLDPE composite films. Particularly, LLDPE composite film with 1% LDH exhibited the optimal performance among all the composite films with a 60.36% enhancement in the water vapor barrier property and a 45.73 °C increase in the temperature of maximum mass loss rate compared with pure LLDPE film. Furthermore, the improved infrared absorbance (1180–914 cm{sup −1}) of LLDPE/LDH films revealed the significant enhancement of heat retention. Therefore, this study prompts the application of LLDPE/LDH films as agricultural films with superior heat retention. - Graphical abstract: The fabrication process of LLDPE/LDH composite films. - Highlights: • LDH with basal spacing of 4.07 nm was synthesized by high-energy ball milling. • LLDPE composite films with homogeneous LDH dispersion were fabricated. • The properties of LLDPE/LDH composite films were improved. • LLDPE/LDH composite films show superior heat retention property.

  15. Large-scale fabrication of linear low density polyethylene/layered double hydroxides composite films with enhanced heat retention, thermal, mechanical, optical and water vapor barrier properties

    International Nuclear Information System (INIS)

    Xie, Jiazhuo; Zhang, Kun; Zhao, Qinghua; Wang, Qingguo; Xu, Jing

    2016-01-01

    Novel LDH intercalated with organic aliphatic long-chain anion was large-scale synthesized innovatively by high-energy ball milling in one pot. The linear low density polyethylene (LLDPE)/layered double hydroxides (LDH) composite films with enhanced heat retention, thermal, mechanical, optical and water vapor barrier properties were fabricated by melt blending and blowing process. FT IR, XRD, SEM results show that LDH particles were dispersed uniformly in the LLDPE composite films. Particularly, LLDPE composite film with 1% LDH exhibited the optimal performance among all the composite films with a 60.36% enhancement in the water vapor barrier property and a 45.73 °C increase in the temperature of maximum mass loss rate compared with pure LLDPE film. Furthermore, the improved infrared absorbance (1180–914 cm −1 ) of LLDPE/LDH films revealed the significant enhancement of heat retention. Therefore, this study prompts the application of LLDPE/LDH films as agricultural films with superior heat retention. - Graphical abstract: The fabrication process of LLDPE/LDH composite films. - Highlights: • LDH with basal spacing of 4.07 nm was synthesized by high-energy ball milling. • LLDPE composite films with homogeneous LDH dispersion were fabricated. • The properties of LLDPE/LDH composite films were improved. • LLDPE/LDH composite films show superior heat retention property.

  16. Optical Properties of Hybrid Nanomaterials

    Indian Academy of Sciences (India)

    owner

    K. George Thomas. Photosciences & Photonics Group. National Institute for Interdisciplinary. Science and Technology (NIIST), CSIR,. Trivandrum- 695 019, INDIA. (kgt@vsnl.com). Optical Properties of Hybrid. Nanomaterials ...

  17. Optical properties of graphene superlattices.

    Science.gov (United States)

    Le, H Anh; Ho, S Ta; Nguyen, D Chien; Do, V Nam

    2014-10-08

    In this work, the optical responses of graphene superlattices, i.e. graphene subjected to a periodic scalar potential, are theoretically reported. The optical properties were studied by investigating the optical conductivity, which was calculated using the Kubo formalism. It was found that the optical conductivity becomes dependent on the photon polarization and is suppressed in the photon energy range of (0, Ub), where Ub is the potential barrier height. In the higher photon energy range, i.e. Ω > Ub, the optical conductivity is, however, almost identical to that of pristine graphene. Such behaviors of the optical conductivity are explained microscopically through the analysis of the elements of optical matrices and effectively through a simple model, which is based on the Pauli blocking mechanism.

  18. Optical properties of graphene superlattices

    International Nuclear Information System (INIS)

    Le, H Anh; Do, V Nam; Ho, S Ta; Nguyen, D Chien

    2014-01-01

    In this work, the optical responses of graphene superlattices, i.e. graphene subjected to a periodic scalar potential, are theoretically reported. The optical properties were studied by investigating the optical conductivity, which was calculated using the Kubo formalism. It was found that the optical conductivity becomes dependent on the photon polarization and is suppressed in the photon energy range of (0, U b ), where U b is the potential barrier height. In the higher photon energy range, i.e. Ω > U b , the optical conductivity is, however, almost identical to that of pristine graphene. Such behaviors of the optical conductivity are explained microscopically through the analysis of the elements of optical matrices and effectively through a simple model, which is based on the Pauli blocking mechanism. (paper)

  19. Preparation and characterization of RF magnetron sputtered CuO/CaTi{sub 4}O{sub 9} thin films with enhanced third-order nonlinear optical properties

    Energy Technology Data Exchange (ETDEWEB)

    Yin, Congfei; Liang, Xiaojuan, E-mail: lxj6126@126.com; Hu, Guangcai; Hu, Xie; Chen, Xipeng; Li, Pengzhi; Xiang, Weidong, E-mail: xiangweidong001@126.com

    2017-04-15

    The titanate, is a material of interest for various energy applications, including photovoltaics, catalysts, and high-rate energy storage devices. Herein, its related materials, CuO/CaTi{sub 4}O{sub 9} [CCTO] thin films, were successfully fabricated on SrTiO{sub 3} (100) substrates by RF magnetron sputtering assisted with subsequent oxygen annealing. This obtained CCTO thin films were then systemically studied by X-ray powder diffraction (XRD), atomic force microscopy (AFM), scan electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and high-resolution transmission electron microscopy (HRTEM). It was found that CuO and CaTi{sub 4}O{sub 9} (001) particles were closely accumulated together on the surface of the substrate in the annealing process after comparing with that of the as-prepared thin film, which was verified by SEM and AFM results. Furthermore, we investigated the third-order nonlinear optical (NLO) properties of the as-prepared and annealed CCTO thin film by means of the Z-scan technique using 650 nm femtosecond laser pulse. Post-deposition oxygen annealing was found to modify the morphological characteristics of the films, resulting in enhancing their NLO properties. The observation of NLO performance of annealed CCTO thin film indicates that RF magnetron sputtering is a feasible method for the fabrication of optical thin films, which can be expanded to fabricate other NLO materials from the corresponding dispersions. Naturally, we concluded that the CCTO thin film occupy a better NLO property, and thus enlarge its application in nonlinear optics. - Highlights: • The CCTO thin film was prepared using the RF magnetron sputtering and oxygen annealing. • The film was prepared on the SrTiO{sub 3}(100) substrates with a Ca{sub 2}CuO{sub 3} target. • The oxygen annealing was found can effectively enhance the film quality and NLO property. • The film was characterized using XPS, SEM, AFM, TEM, XRD and Z-scan techniques.

  20. Optical limiting properties of optically active phthalocyanine derivatives

    Science.gov (United States)

    Wang, Peng; Zhang, Shuang; Wu, Peiji; Ye, Cheng; Liu, Hongwei; Xi, Fu

    2001-06-01

    The optical limiting properties of four optically active phthalocyanine derivatives in chloroform solutions and epoxy resin thin plates were measured at 532 nm with 10 ns pulses. The excited state absorption cross-section σex and refractive-index cross-section σr were determined with the Z-scan technique. These chromophores possess larger σex than the ground state absorption cross-section σ0, indicating that they are the potential materials for reverse saturable absorption (RSA). The negative σr values of these chromophores add to the thermal contribution, producing a larger defocusing effect, which may be helpful in further enhancing their optical limiting performance. The optical limiting responses of the thin plate samples are stronger than those of the chloroform solutions.

  1. Optical properties of phosphorene

    International Nuclear Information System (INIS)

    Yang, Jiong; Lu Yuerui

    2017-01-01

    Phosphorene is a two-dimensional semiconductor with layers-dependent bandgap in the near-infrared range and it has attracted a great deal of attention due to its high anisotropy and carrier mobility. The highly anisotropic nature of phosphorene has been demonstrated through Raman and polarization photoluminescence measurements. Photoluminescence spectroscopy has also revealed the layers-dependent bandgap of phosphorene. Furthermore, due to the reduced dimensionality and screening in phosphorene, excitons and trions can stably exist at elevated temperatures and have large binding energies. The exciton and trion dynamics are thus detected by applying electrical bias or optical injection to the phosphorene system. Finally, various optical and optoelectronic applications based on phosphorene have been demonstrated and discussed. (topical reviews)

  2. Systems and methods for enhancing optical information

    Science.gov (United States)

    DeVore, Peter Thomas Setsuda; Chou, Jason T.

    2018-01-02

    An Optical Information Transfer Enhancer System includes a first system for producing an information bearing first optical wave that is impressed with a first information having a first information strength wherein the first optical wave has a first shape. A second system produces a second optical wave. An information strength enhancer module receives the first and said second optical waves and impresses the first optical wave upon the second optical wave via cross-phase modulation (XPM) to produce an information-strength-enhanced second optical wave having a second information strength that is greater than the first information strength of the first optical wave. Following a center-wavelength changer by an Optical Information Transfer Enhancer System improves its performance.

  3. Optical and passivating properties of hydrogenated amorphous silicon nitride deposited by plasma enhanced chemical vapour deposition for application on silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Wight, Daniel Nilsen

    2008-07-01

    Within this thesis, several important subjects related to the use of amorphous silicon nitride made by plasma enhanced chemical vapour deposition as an anti-reflective coating on silicon solar cells are presented. The first part of the thesis covers optical simulations to optimise single and double layer anti-reflective coatings with respect to optical performance when situated on a silicon solar cell. The second part investigates the relationship between important physical properties of silicon nitride films when deposited under different conditions. The optical simulations were either based on minimising the reflectance off a silicon nitride/silicon wafer stack or maximising the transmittance through the silicon nitride into the silicon wafer. The former method allowed consideration of the reflectance off the back surface of the wafer, which occurs typically at wavelengths above 1000 nm due to the transparency of silicon at these wavelengths. However, this method does not take into consideration the absorption occurring in the silicon nitride, which is negligible at low refractive indexes but quite significant when the refractive index increases above 2.1. For high-index silicon nitride films, the latter method is more accurate as it considers both reflectance and absorbance in the film to calculate the transmittance into the Si wafer. Both methods reach similar values for film thickness and refractive index for optimised single layer anti-reflective coatings, due to the negligible absorption occurring in these films. For double layer coatings, though, the reflectance based simulations overestimated the optimum refractive index for the bottom layer, which would have lead to excessive absorption if applied to real anti-reflective coatings. The experimental study on physical properties for silicon nitride films deposited under varying conditions concentrated on the estimation of properties important for its applications, such as optical properties, passivation

  4. Morphological and optical properties changes in nanocrystalline Si (nc-Si) deposited on porous aluminum nanostructures by plasma enhanced chemical vapor deposition for Solar energy applications

    Energy Technology Data Exchange (ETDEWEB)

    Ghrib, M., E-mail: mondherghrib@yahoo.fr [Laboratoire de Photovoltaique (L.P.V.), Centre de Recherche et des Technologies de l' Energie, BP 95, Hammam-Lif 2050 (Tunisia); Gaidi, M.; Ghrib, T.; Khedher, N. [Laboratoire de Photovoltaique (L.P.V.), Centre de Recherche et des Technologies de l' Energie, BP 95, Hammam-Lif 2050 (Tunisia); Ben Salam, M. [L3M, Department of Physics, Faculty of Sciences of Bizerte, 7021 Zarzouna (Tunisia); Ezzaouia, H. [Laboratoire de Photovoltaique (L.P.V.), Centre de Recherche et des Technologies de l' Energie, BP 95, Hammam-Lif 2050 (Tunisia)

    2011-08-15

    Photoluminescence (PL) spectroscopy was used to determine the electrical band gap of nanocrystalline silicon (nc-Si) deposited by plasma enhancement chemical vapor deposition (PECVD) on porous alumina structure by fitting the experimental spectra using a model based on the quantum confinement of electrons in Si nanocrystallites having spherical and cylindrical forms. This model permits to correlate the PL spectra to the microstructure of the porous aluminum silicon layer (PASL) structure. The microstructure of aluminum surface layer and nc-Si films was systematically studied by atomic force microscopy (AFM), transmission electron microscopy (TEM), Raman spectroscopy and X-ray diffraction (XRD). It was found that the structure of the nanocrystalline silicon layer (NSL) is dependent of the porosity (void) of the porous alumina layer (PAL) substrate. This structure was performed in two steps, namely the PAL substrate was prepared using sulfuric acid solution attack on an Al foil and then the silicon was deposited by plasma enhanced chemical vapor deposition (PECVD) on it. The optical constants (n and k as a function of wavelength) of the deposited films were obtained using variable angle spectroscopic ellipsometry (SE) in the UV-vis-NIR regions. The SE spectrum of the porous aluminum silicon layer (PASL) was modeled as a mixture of void, crystalline silicon and aluminum using the Cauchy model approximation. The specific surface area (SSA) was estimated and was found to decrease linearly when porosity increases. Based on this full characterization, it is demonstrated that the optical characteristics of the films are directly correlated to their micro-structural properties.

  5. Morphological and optical properties changes in nanocrystalline Si (nc-Si) deposited on porous aluminum nanostructures by plasma enhanced chemical vapor deposition for Solar energy applications

    International Nuclear Information System (INIS)

    Ghrib, M.; Gaidi, M.; Ghrib, T.; Khedher, N.; Ben Salam, M.; Ezzaouia, H.

    2011-01-01

    Photoluminescence (PL) spectroscopy was used to determine the electrical band gap of nanocrystalline silicon (nc-Si) deposited by plasma enhancement chemical vapor deposition (PECVD) on porous alumina structure by fitting the experimental spectra using a model based on the quantum confinement of electrons in Si nanocrystallites having spherical and cylindrical forms. This model permits to correlate the PL spectra to the microstructure of the porous aluminum silicon layer (PASL) structure. The microstructure of aluminum surface layer and nc-Si films was systematically studied by atomic force microscopy (AFM), transmission electron microscopy (TEM), Raman spectroscopy and X-ray diffraction (XRD). It was found that the structure of the nanocrystalline silicon layer (NSL) is dependent of the porosity (void) of the porous alumina layer (PAL) substrate. This structure was performed in two steps, namely the PAL substrate was prepared using sulfuric acid solution attack on an Al foil and then the silicon was deposited by plasma enhanced chemical vapor deposition (PECVD) on it. The optical constants (n and k as a function of wavelength) of the deposited films were obtained using variable angle spectroscopic ellipsometry (SE) in the UV-vis-NIR regions. The SE spectrum of the porous aluminum silicon layer (PASL) was modeled as a mixture of void, crystalline silicon and aluminum using the Cauchy model approximation. The specific surface area (SSA) was estimated and was found to decrease linearly when porosity increases. Based on this full characterization, it is demonstrated that the optical characteristics of the films are directly correlated to their micro-structural properties.

  6. Optical, mechanical and surface properties of amorphous carbonaceous thin films obtained by plasma enhanced chemical vapor deposition and plasma immersion ion implantation and deposition

    Science.gov (United States)

    Turri, Rafael G.; Santos, Ricardo M.; Rangel, Elidiane C.; da Cruz, Nilson C.; Bortoleto, José R. R.; Dias da Silva, José H.; Antonio, César Augusto; Durrant, Steven F.

    2013-09-01

    Diverse amorphous hydrogenated carbon-based films (a-C:H, a-C:H:F, a-C:H:N, a-C:H:Cl and a-C:H:Si:O) were obtained by radiofrequency plasma enhanced chemical vapor deposition (PECVD) and plasma immersion ion implantation and deposition (PIIID). The same precursors were used in the production of each pair of each type of film, such as a-C:H, using both PECVD and PIIID. Optical properties, namely the refractive index, n, absorption coefficient, α, and optical gap, ETauc, of these films were obtained via transmission spectra in the ultraviolet-visible near-infrared range (wavelengths from 300 to 3300 nm). Film hardness, elastic modulus and stiffness were obtained as a function of depth using nano-indentation. Surface energy values were calculated from liquid drop contact angle data. Film roughness and morphology were assessed using atomic force microscopy (AFM). The PIIID films were usually thinner and possessed higher refractive indices than the PECVD films. Determined refractive indices are consistent with literature values for similar types of films. Values of ETauc were increased in the PIIID films compared to the PECVD films. An exception was the a-C:H:Si:O films, for which that obtained by PIIID was thicker and exhibited a decreased ETauc. The mechanical properties - hardness, elastic modulus and stiffness - of films produced by PECVD and PIIID generally present small differences. An interesting effect is the increase in the hardness of a-C:H:Cl films from 1.0 to 3.0 GPa when ion implantation is employed. Surface energy correlates well with surface roughness. The implanted films are usually smoother than those obtained by PECVD.

  7. Optical, mechanical and surface properties of amorphous carbonaceous thin films obtained by plasma enhanced chemical vapor deposition and plasma immersion ion implantation and deposition

    International Nuclear Information System (INIS)

    Turri, Rafael G.; Santos, Ricardo M.; Rangel, Elidiane C.; Cruz, Nilson C. da; Bortoleto, José R.R.; Dias da Silva, José H.; Antonio, César Augusto; Durrant, Steven F.

    2013-01-01

    Diverse amorphous hydrogenated carbon-based films (a-C:H, a-C:H:F, a-C:H:N, a-C:H:Cl and a-C:H:Si:O) were obtained by radiofrequency plasma enhanced chemical vapor deposition (PECVD) and plasma immersion ion implantation and deposition (PIIID). The same precursors were used in the production of each pair of each type of film, such as a-C:H, using both PECVD and PIIID. Optical properties, namely the refractive index, n, absorption coefficient, α, and optical gap, E Tauc , of these films were obtained via transmission spectra in the ultraviolet–visible near-infrared range (wavelengths from 300 to 3300 nm). Film hardness, elastic modulus and stiffness were obtained as a function of depth using nano-indentation. Surface energy values were calculated from liquid drop contact angle data. Film roughness and morphology were assessed using atomic force microscopy (AFM). The PIIID films were usually thinner and possessed higher refractive indices than the PECVD films. Determined refractive indices are consistent with literature values for similar types of films. Values of E Tauc were increased in the PIIID films compared to the PECVD films. An exception was the a-C:H:Si:O films, for which that obtained by PIIID was thicker and exhibited a decreased E Tauc . The mechanical properties – hardness, elastic modulus and stiffness – of films produced by PECVD and PIIID generally present small differences. An interesting effect is the increase in the hardness of a-C:H:Cl films from 1.0 to 3.0 GPa when ion implantation is employed. Surface energy correlates well with surface roughness. The implanted films are usually smoother than those obtained by PECVD.

  8. Enhancement of the optical, thermal and electrical properties of PEO/PAM:Li polymer electrolyte films doped with Ag nanoparticles

    Science.gov (United States)

    Morsi, M. A.; El-Khodary, Sherif A.; Rajeh, A.

    2018-06-01

    Both lithium bromide (LiBr) and biosynthesized silver nanoparticles (Ag NPs) with average size 2-30 nm have been incorporated into the polymeric matrix of polyethylene oxide and polyacrylamide (PEO/PAM) blend by the casting method. FT-IR analysis indicates the formation of hydrogen bond between the blend components. Also, LiBr and Ag NPs interact with the functional groups of PEO/PAM matrix. The results of XRD analysis depict the semi-crystalline nature of these polymer samples and the degree of crystallinity is decreased due to the addition process. The values of optical energy gap from UV-Vis. data are decreased from 3.55 eV for blend to 3.26 for the nanocomposite sample in the indirect transition. LiBr/Ag NPs assist the improvement of the thermal stability of the PEO/PAM blend, as evidenced by TGA and DTA techniques. Upon the addition of LiBr and Ag NPs, an improvement for the conductivity, dielectric permittivity (έ) and dielectric loss (ἕ) of PEO/PAM solid polymer electrolytes are observed. It's clear that the improvement of the electrical conductivity and dielectric parameters for PEO/PAM: Li+/Ag NPs polymer electrolyte system makes it as a promising candidate for solid-state Li battery applications.

  9. Plasmon-enhanced optically stimulated luminescence

    Energy Technology Data Exchange (ETDEWEB)

    Guidelli, E. J.; Baffa, O. [Universidade de Sao Paulo, Faculdade de Filosofia, Ciencias e Letras de Ribeirao Preto, Departamento de Fisica, Av. Bandeirantes 3900, 14040-901 Ribeirao Preto, Sao Paulo (Brazil); Ramos, A. P., E-mail: ederguidelli@gmail.com [Universidade de Sao Paulo, Faculdade de Filosofia, Ciencias e Letras de Ribeirao Preto, Departamento de Quimica, Av. Bandeirantes 3900, 14040-901 Ribeirao Preto, Sao Paulo (Brazil)

    2015-10-15

    Full text: Optically Stimulated Luminescence dosimeters (OSLD) have been largely used for personal, medical, and industrial radiation dosimetry. Developing highly sensitive and small-sized radiation detectors and dosimeters is essential for improving spatial resolution and consequently diagnosis quality and treatment efficacy in the case of applications in radiodiagnosis and radiation therapy, for instance. Conventional methods to improve the OSLD sensitivity consist of doping and co-doping the host materials with atoms of other elements, thereby increasing the amount of trapping and/or luminescent centers. Our group is researching on the use of the plasmon properties of noble metal nanoparticles to increase OSL intensity. Upon incidence of a light beam with appropriate resonant wavelengths, the oscillation of the free electrons at the nanoparticle surface originates the Localized Surface Plasmons (LSP) and the consequent plasmon resonance band. The interaction between the LSP and the surrounding luminescent material leads to new optical properties largely employed for enhancing several luminescent processes. Here we will show our results regarding the use of LSP to increase OSLD sensitivity. The interaction between the traps/luminescent centers and the plasmons depends on the distance between them, on the plasmon resonance band intensity and position, as well as on the surrounding medium. Therefore, the plasmon-enhanced luminescence is a promising tool to develop more sensitive and miniaturized OSLD. (Author)

  10. Plasmon-enhanced optically stimulated luminescence

    International Nuclear Information System (INIS)

    Guidelli, E. J.; Baffa, O.; Ramos, A. P.

    2015-10-01

    Full text: Optically Stimulated Luminescence dosimeters (OSLD) have been largely used for personal, medical, and industrial radiation dosimetry. Developing highly sensitive and small-sized radiation detectors and dosimeters is essential for improving spatial resolution and consequently diagnosis quality and treatment efficacy in the case of applications in radiodiagnosis and radiation therapy, for instance. Conventional methods to improve the OSLD sensitivity consist of doping and co-doping the host materials with atoms of other elements, thereby increasing the amount of trapping and/or luminescent centers. Our group is researching on the use of the plasmon properties of noble metal nanoparticles to increase OSL intensity. Upon incidence of a light beam with appropriate resonant wavelengths, the oscillation of the free electrons at the nanoparticle surface originates the Localized Surface Plasmons (LSP) and the consequent plasmon resonance band. The interaction between the LSP and the surrounding luminescent material leads to new optical properties largely employed for enhancing several luminescent processes. Here we will show our results regarding the use of LSP to increase OSLD sensitivity. The interaction between the traps/luminescent centers and the plasmons depends on the distance between them, on the plasmon resonance band intensity and position, as well as on the surrounding medium. Therefore, the plasmon-enhanced luminescence is a promising tool to develop more sensitive and miniaturized OSLD. (Author)

  11. Ag nanoparticles-decorated ZnO nanorod array on a mechanical flexible substrate with enhanced optical and antimicrobial properties

    Science.gov (United States)

    Chen, Yi; Tse, Wai Hei; Chen, Longyan; Zhang, Jin

    2015-03-01

    Heteronanostructured zinc oxide nanorod (ZnO NR) array are vertically grown on polydimethylsiloxane (PDMS) through a hydrothermal method followed by an in situ deposition of silver nanoparticles (Ag NPs) through a photoreduction process. The Ag-ZnO heterostructured nanorods on PDMS are measured with an average diameter of 160 nm and an average length of 2 μm. ZnO NRs measured by high-resolution transmission electron microscope (HRTEM) shows highly crystalline with a lattice fringe of 0.255 nm, which corresponds to the (0002) planes in ZnO crystal lattice. The average diameter of the Ag NPs in situ deposited on the ZnO NRs is estimated at 22 ± 2 nm. As compared to the bare ZnO NRs, the heterostructured Ag-ZnO nanorod array shows enhanced ultraviolet (UV) absorption at 440 nm, and significant emission in the visible region (λem = 542 nm). In addition, the antimicrobial efficiency of Ag-ZnO heterostructured nanorod array shows obvious improvement as compared to bare ZnO nanorod array. The cytotoxicity of ZnO nanorod array with and without Ag NPs was studied by using 3 T3 mouse fibroblast cell line. No significant toxic effect is imposed on the cells.

  12. Effect of the hydrogen flow rate on the structural and optical properties of hydrogenated amorphous silicon thin films prepared by plasma enhanced chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Ben Amor, Sana; Dimassi, Wissem; Ali Tebai, Mohamed; Ezzaouia, Hatem [Photovoltaic Laboratory Research and Technology Centre of Energy, Borj-Cedria Science and Technology Park, BP 95, 2050 Hammam-Lif (Tunisia)

    2012-10-15

    Hydrogenated amorphous silicon (a-Si:H) thin films were deposited from pure silane (SiH{sub 4}) and hydrogen (H{sub 2}) gas mixture by plasma enhanced chemical vapor deposition (PECVD) method at low temperature (400 C) using high rf power (60 W). The structural and optical properties of these films are systematically investigated as a function of the flow rate of hydrogen (F{sub H2}).The surface morphology is analyzed by atomic force microscopy (AFM). The characterization of these films with low angle X-ray diffraction revealed that the crystallite size in the films tends to decrease with increase in (F{sub H2}). The Fourier transform infrared (FTIR) spectroscopic analysis showed that at low values of (F{sub H2}),the hydrogen bonding in Si:H films shifts from di-hydrogen (Si-H{sub 2}) and (Si-H{sub 2})n complexes to the mono-hydrogen (Si-H) bonding configuration. Finally, for these optimized conditions, the deposition rate decreases with increasing (F{sub H2}). (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  13. Thermo-optical properties of optically stimulated luminescence in feldspars

    DEFF Research Database (Denmark)

    Poolton, N.R.J.; Bøtter-Jensen, L.; Johnsen, O.

    1995-01-01

    Optically stimulated luminescence processes in feldspars are subject to competing thermal enhancement and quenching processes: this article describes the thermal enhancement effects for orthoclase, albite and plagioclase feldspars. It is demonstrated that certain lattice vibrational modes can be ...

  14. Optical properties of nitride nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Cantarero, A.; Cros, A.; Garro, N.; Gomez-Gomez, M.I.; Garcia, A.; Lima, M.M. de [Materials Science Institute, University of Valencia, PO Box 22085, 46071 Valencia (Spain); Daudin, B. [Departement de Recherche Fondamentale sur la Matiere Condensee, SPMM, CEA/Grenoble, 17 Rue des Martyrs, 38054 Grenoble (France); Rizzi, A.; Denker, C.; Malindretos, J. [IV. Physikalisches Institut, Georg August Universitaet Goettingen, 37073 Goettingen (Germany)

    2011-01-15

    In this paper we review some recent results on the optical properties of nitride nanostructures, in particular on GaN quantum dots (QDs) and InN nanocolumns (NCs). First, we will give a brief introduction on the particularities of vibrational modes of wurtzite. The GaN QDs, embedded in AlN, were grown by molecular beam epitaxy (MBE) in the Stransky-Krastanov mode on c- and a-plane 6H-SiC. We have studied the optical properties by means of photoluminescence (PL) and performed Raman scattering measurements to analyze the strain relaxation in the dots and the barrier, the effect of the internal electric fields, and the influence of specific growth parameters, like the influence of capping or the spacer on the relaxation of the QDs. A theoretical model, based on continuous elastic theory, were developed to interpret the Raman scattering results. On the other hand, InN NCs have been grown by MBE in the vapor-liquid-solid mode using Au as a catalyst. The nanocolumns have different morphology depending on the growth conditions. The optical properties can be correlated to the morphology of the samples and the best growth conditions can be selected. We observe, from the analysis of the Raman data in InN NCs, the existence of two space regions contributing to the scattering: the surface and the inner region. From the inner region, uncoupled phonon modes are clearly observed, showing the high crystal quality and the complete relaxation of the NCs (no strain). The observation of a LO-phonon-plasmon couple in the same spectra is a fingerprint of the accumulation layer predicted at the surface of the nanocolumns. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  15. Optical properties of carbon nanotubes

    Science.gov (United States)

    Chen, Gugang

    This thesis addresses the optical properties of novel carbon filamentary nanomaterials: single-walled carbon nanotubes (SWNTs), double-walled carbon nanotubes (DWNTs), and SWNTs with interior C60 molecules ("peapods"). Optical reflectance spectra of bundled SWNTs are discussed in terms of their electronic energy band structure. An Effective Medium Model for a composite material was found to provide a reasonable description of the spectra. Furthermore, we have learned from optical absorption studies of DWNTs and C60-peapods that the host tube and the encapsulant interact weakly; small shifts in interband absorption structure were observed. Resonant Raman scattering studies on SWNTs synthesized via the HiPCO process show that the "zone-folding" approximation for phonons and electrons works reasonably well, even for small diameter (d effect, rather than the vdW interaction. Finally, we studied the chemical doping of DWNTs, where the dopant (Br anions) is chemically bound to the outside of the outer tube. The doped DWNT system is a model for a cylindrical molecular capacitor. We found experimentally that 90% of the positive charge resides on the outer tube, so that most of electric field on the inner tube is screened, i.e., we have observed a molecular Faraday cage effect. A self-consistent theoretical model in the tight-binding approximation with a classical electrostatic energy term is in good agreement with our experimental results.

  16. Structural, optical and mechanical properties of thin diamond and silicon carbide layers grown by low pressure microwave linear antenna plasma enhanced chemical vapour deposition

    Czech Academy of Sciences Publication Activity Database

    Taylor, Andrew; Drahokoupil, Jan; Fekete, Ladislav; Klimša, Ladislav; Kopeček, Jaromír; Purkrt, Adam; Remeš, Zdeněk; Čtvrtlík, Radim; Tomáštík, Jan; Frank, Otakar; Janíček, P.; Mistrík, J.; Mortet, Vincent

    2016-01-01

    Roč. 69, Oct (2016), s. 13-18 ISSN 0925-9635 R&D Projects: GA MŠk LO1409; GA TA ČR TA03010743; GA ČR GA13-31783S; GA MŠk(CZ) LD14011; GA MŠk LM2015088 Grant - others:FUNBIO(XE) CZ.2.16/3.1.00/21568; AV ČR(CZ) Fellowship J. E. Purkyně Institutional support: RVO:68378271 ; RVO:61388955 Keywords : diamond * silicon carbide * adherence * mechanical properties * optical properties Subject RIV: BM - Solid Matter Physics ; Magnetism; CG - Electrochemistry (UFCH-W) Impact factor: 2.561, year: 2016

  17. Optical properties of polymer nanocomposites

    Indian Academy of Sciences (India)

    Wintec

    , optical sensors, optical data communication and optical ... our filters (Leon et al 2001), solar cells and optical sen- sors (Tanaka et al 1991; Tokizaki et .... volume fractions (Top panel: tanψ for volume fractions, 1⋅2%. (dash) and 0⋅6% (dot); ...

  18. Synthesis and optical properties studies

    Directory of Open Access Journals (Sweden)

    N.A. El-Ghamaz

    2017-01-01

    Full Text Available 4-(4-Amino-1,5-dimethyl-2-phenyl-1,2-dihydro-pyrazol-3-ylideneamino-phenol (L1 and 4-(4-Amino-1,5-dimethyl-2-phenyl-1,2-dihydro-pyrazol-3-ylideneamino-benzoic acid (L2 have been synthesized by the condensation reaction of 4-aminoantipyrine (4-AAP and 4-aminophenol or 4-aminobenzoic acid in ethanolic solution and are characterized by various physico-chemical techniques. Thin films of L1 and L2 have been prepared by the conventional spin coating technique. X-ray diffraction patterns (XRD show an amorphous nature for both powder and thin films for L1 and L2 ligands. The optical absorption and refraction properties of L1 and L2 are investigated by spectrophotometric techniques at normal incidence of light in the wavelength range of 200–2500 nm. The absorption spectra show two peaks in the UV region which correspond to π → π∗ transition and a peak in UV–Vis region which may correspond to n → π∗ transition. The values of dispersion parameters Eo, Ed, εL, ε∞ and N/m* are calculated according to the single oscillator model. The presence of the OH group increases the value of ε∞ from 3.21 to 3.32 and the value of N/m* from 7.38 × 1053 to 2.08 × 1054 m−3Kg−1. The optical band transition is found to be indirect allowing fundamental energy gap values of 3.4 and 3.9 eV and onset energy gap values of 2.1 and 2.6 eV for L1 and L2, respectively.

  19. Optical Properties of Rotationally Twinned Nanowire Superlattices

    DEFF Research Database (Denmark)

    Bao, Jiming; Bell, David C.; Capasso, Federico

    2008-01-01

    We have developed a technique so that both transmission electron microscopy and microphotoluminescence can be performed on the same semiconductor nanowire over a large range of optical power, thus allowing us to directly correlate structural and optical properties of rotationally twinned zinc...... a heterostructure in a chemically homogeneous nanowire material and alter in a major way its optical properties opens new possibilities for band-structure engineering....

  20. Nonlinear optical properties of silicon waveguides

    International Nuclear Information System (INIS)

    Tsang, H K; Liu, Y

    2008-01-01

    Recent work on two-photon absorption (TPA), stimulated Raman scattering (SRS) and optical Kerr effect in silicon-on-insulator (SOI) waveguides is reviewed and some potential applications of these optical nonlinearities, including silicon-based autocorrelation detectors, optical amplifiers, high speed optical switches, optical wavelength converters and self-phase modulation (SPM), are highlighted. The importance of free carriers generated by TPA in nonlinear devices is discussed, and a generalized definition of the nonlinear effective length to cater for nonlinear losses is proposed. How carrier lifetime engineering, and in particular the use of helium ion implantation, can enhance the nonlinear effective length for nonlinear devices is also discussed

  1. Chiral nanophotonics chiral optical properties of plasmonic systems

    CERN Document Server

    Schäferling, Martin

    2017-01-01

    This book describes the physics behind the optical properties of plasmonic nanostructures focusing on chiral aspects. It explains in detail how the geometry determines chiral near-fields and how to tailor their shape and strength. Electromagnetic fields with strong optical chirality interact strongly with chiral molecules and, therefore, can be used for enhancing the sensitivity of chiroptical spectroscopy techniques. Besides a short review of the latest results in the field of plasmonically enhanced enantiomer discrimination, this book introduces the concept of chiral plasmonic near-field sources for enhanced chiroptical spectroscopy. The discussion of the fundamental properties of these light sources provides the theoretical basis for further optimizations and is of interest for researchers at the intersection of nano-optics, plasmonics and stereochemistry. .

  2. Photorefractive optics materials, properties, and applications

    CERN Document Server

    Yu, Francis T S

    1999-01-01

    The advances of photorefractive optics have demonstrated many useful and practical applications, which include the development of photorefractive optic devices for computer communication needs. To name a couple significant applications: the large capacity optical memory, which can greatly improve the accessible high-speed CD-ROM and the dynamic photorefractive gratings, which can be used for all-optic switches for high-speed fiber optic networks. This book is an important reference both for technical and non-technical staffs who are interested in this field. * Covers the recent development in materials, phenomena, and applications * Includes growth, characterization, dynamic gratings, and liquid crystal PR effect * Includes applications to photonic devices such as large capacity optical memory, 3-D interconnections, and dynamic holograms * Provides the recent overall picture of current trends in photorefractive optics * Includes optical and electronic properties of the materials as applied to dynamic photoref...

  3. Enhanced Optical and Electrical Properties of TiO{sub 2} Buffered IGZO/TiO{sub 2} Bi-Layered Films

    Energy Technology Data Exchange (ETDEWEB)

    Moon, Hyun-Joo; Kim, Daeil [University of Ulsan, Ulsan (Korea, Republic of)

    2016-08-15

    In and Ga doped ZnO (IGZO, 100-nm thick) thin films were deposited by radio frequency magnetron sputtering without intentional substrate heating on a bare glass substrate and a TiO{sub 2}-deposited glass substrate to determine the effect of the thickness of a thin TiO{sub 2} buffer layer on the structural, optical, and electrical properties of the films. The thicknesses of the TiO{sub 2} buffer layers were 5, 10 and 15 nm, respectively. As-deposited IGZO films with a 10 nm-thick TiO{sub 2} buffer layer had an average optical transmittance of 85.0% with lower resistivity (1.83×10-2 Ω cm) than that of IGZO single layer films. The figure of merit (FOM) reached a maximum of 1.44×10-4 Ω-1 for IGZO/10 nm-thick TiO{sub 2} bi-layered films, which is higher than the FOM of 6.85×10-5 Ω-1 for IGZO single layer films. Because a higher FOM value indicates better quality transparent conducting oxide (TCO) films, the IGZO/10 nm-thick TiO{sub 2} bi-layered films are likely to perform better in TCO applications than IGZO single layer films.

  4. Radiative properties of optical board embedded with optical black holes

    International Nuclear Information System (INIS)

    Qiu, J.; Liu, L.H.; Hsu, P.-F.

    2011-01-01

    Unique radiative properties, such as wavelength-selective transmission or absorption, have been intensively studied. Historically, geometries for wavelength-selective of light absorption were developed based on metallic periodical structures, which were only applied in the case of TM wave incidence due to the excitation of surface plasmons. In this paper, we develop an alternative approach to selective wavelength of light absorption (both TE and TM waves), based on an optical board periodical embedded with optical black holes. Numerical work was carried out to study such structure's radiative properties within the wavelength range of 1-100 μm. The electromagnetic wave transmission through such a structure is predicted by solving Maxwell's equations using the finite-difference time-domain (FDTD) method. Spectral absorptance varies with the period of optical black holes. When the incidence wavelength is much larger than the inner core radius, most of the light energy will be transmitted through the inner core. Otherwise, the energy will be mainly absorbed. Numerical results of the radiative properties of the optical board with different incidence wavelengths are also obtained. The effect of the oblique incidence wave is investigated. This study helps us gain a better understanding of the radiative properties of an optical board embedded with optical black holes and develop an alternative approach to selective light absorption.

  5. Temperature dependence of PZT film optical properties

    Czech Academy of Sciences Publication Activity Database

    Deineka, Alexander; Jastrabík, Lubomír; Suchaneck, G.; Gerlach, G.

    11-12, - (2001), s. 352-354 ISSN 0447-6441 R&D Projects: GA ČR GA202/00/1425; GA MŠk LN00A015 Institutional research plan: CEZ:AV0Z1010914 Keywords : refractive index profile * PZT film * temperature dependence of optical properties Subject RIV: BH - Optics, Masers, Lasers

  6. The CLASS blazar survey - II. Optical properties

    NARCIS (Netherlands)

    Caccianiga, A; Marcha, MJ; Anton, S; Mack, KH; Neeser, MJ

    2002-01-01

    This paper presents the optical properties of the objects selected in the CLASS blazar survey. Because an optical spectrum is now available for 70 per cent of the 325 sources present in the sample, a spectral classification, based on the appearance of the emission/absorption lines, is possible. A

  7. Electronic and optical properties of lead iodide

    DEFF Research Database (Denmark)

    Ahuja, R.; Arwin, H.; Ferreira da Silva, A.

    2002-01-01

    The electronic properties and the optical absorption of lead iodide (PbI2) have been investigated experimentally by means of optical absorption and spectroscopic ellipsometry, and theoretically by a full-potential linear muffin-tin-orbital method. PbI2 has been recognized as a very promising...

  8. Handbook of the Properties of Optical Materials

    Science.gov (United States)

    1984-01-01

    EFFECTIVE MASS - - MOBILITY - - A-2 ARSEWIC SELENIOE (As2 Se3 ) OPTICAL PROPERTIES TRANSMISSION RANGE: 9 - 11n Optical Absorption Coefficient = 0.079...of 55 KRS-5 as a function of wavelength. A-2120 ZINC SELENIOE ZnSe 0 STRUCTURE CRYSTALLINE SYMMETRY = Cubic, 43m LATTICE CONSTANTS (A) = a = 5.667

  9. Optical properties of alkaline earth borate glasses

    African Journals Online (AJOL)

    user

    ... devices; radiation shields, surgical lasers and their glass ceramic counter ... Alkaline earth oxides improve glass forming capability while heavy metal ... reports on optical properties of MO-B2O3 glasses containing alkaline earth oxides.

  10. Optical properties of spherical gold mesoparticles

    DEFF Research Database (Denmark)

    Evlyukhin, A. B.; Kuznetsov, A. I.; Novikov, S. M.

    2012-01-01

    Optical properties of spherical gold particles with diameters of 150-650 nm (mesoparticles) are studied by reflectance spectroscopy. Particles are fabricated by laser-induced transfer of metallic droplets onto metal and dielectric substrates. Contributions of higher multipoles (beyond...

  11. Optical and Electrical Properties of Ar+ Implanted PET

    Science.gov (United States)

    Kumar, Rajiv; Shekhawat, Nidhi; Sharma, Annu; Aggarwal, Sanjeev; Kumar, Praveen; Kanjilal, D.

    2011-07-01

    In the present work, the effect of 100 keV argon ion implantation on the optical and electrical properties of PET has been studied. A continuous reduction in optical band gap (from 3.63 to 1.93 eV) with increasing implantation dose has been observed as analyzed using UV-Visible absorption spectroscopy. Current-Voltage (I-V) characteristics have been studied which clearly indicate the enhancement in the conductivity of PET specimens as an effect of implantation. This increase in conductivity has been correlated with the decrease in optical band gap.

  12. Synthesis, structural and optical properties of ZnO spindle/reduced graphene oxide composites with enhanced photocatalytic activity under visible light irradiation

    Science.gov (United States)

    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.

  13. Green synthesis of CuInS2/ZnS core-shell quantum dots by facile solvothermal route with enhanced optical properties

    Science.gov (United States)

    Jindal, Shikha; Giripunje, Sushama M.; Kondawar, Subhash B.; Koinkar, Pankaj

    2018-03-01

    We report an eco-friendly green synthesis of highly luminescent CuInS2/ZnS core-shell quantum dots (QDs) with average particle size ∼ 3.9 nm via solvothermal process. The present study embodies the intensification of CuInS2/ZnS QDs properties by the shell growth on the CuInS2 QDs. The as-prepared CuInS2 core and CuInS2/ZnS core-shell QDs have been characterized using a range of optical and structural techniques. By adopting a low temperature growth of CuInS2 core and high temperature growth of CuInS2/ZnS core-shell growth, the tuning of absorption and photoluminescence emission spectra were observed. Optical absorption and photoluminescence spectroscopy probe the effect of ZnS passivation on the electronic structure of the CuInS2 dots. In addition, QDs have been scrutinized using ultra violet photoelectron spectroscopy (UPS) to explore their electronic band structure. The band level positions of CuInS2 and CuInS2/ZnS QDs suffices the demand of non-toxic acceptor material for electronic devices. The variation in electronic energy levels of CuInS2 core with the coating of wide band gap ZnS shell influence the removal of trap assisted recombination on the surface of the core. QDs exhibited tunable emission from red to orange region. These studies reveal the feasibility of QDs in photovoltaic and light emitting diodes.

  14. Enhanced optomechanical readout using optical coalescence

    DEFF Research Database (Denmark)

    Genes, Claudiu; Xuereb, André; Pupillo, Guido

    2013-01-01

    of a symmetric Fabry-Pérot resonator strongly modifies the cavity response function, such that two longitudinal modes with different spatial parity are brought close to frequency degeneracy and interfere in the cavity output field. In the case of a movable middle reflector we show that the interference...... in this generic “optical coalescence” phenomenon gives rise to an enhanced frequency shift of the peaks of the cavity transmission that can be exploited in optomechanics....

  15. Optical properties of iron oxides

    Science.gov (United States)

    Musfeldt, Janice

    2012-02-01

    Magnetoelectric coupling in materials like multiferroics, dilute magnetic semiconductors, and topological insulators has attracted a great deal of attention, although most work has been done in the static limit. Optical spectroscopy offers a way to investigate the dynamics of charge-spin coupling, an area where there has been much less effort. Using these techniques, we discovered that charge fluctuation in LuFe2O4, the prototypical charge ordered multiferroic, has an onset well below the charge ordering transition, supporting the ``order by fluctuation'' mechanism for the development of charge order superstructure. Bragg splitting and large magneto-optical contrast suggest a low temperature monoclinic distortion that can be driven by both temperature and magnetic field. At the same time, dramatic splitting of the LuO2 layer phonon mode is attributed to charge-rich/poor proximity effects, and its temperature dependence reveals the antipolar nature of the W layer pattern. Using optical techniques, we also discovered that α-Fe2O3, a chemically-similar parent compound and one of the world's oldest and most iconic antiferromagnetic materials, appears more red in applied magnetic field than in zero field conditions. This effect is driven by a field-induced reorientation of magnetic order. The oscillator strength lost in the color band is partially transferred to the magnon side band, a process that also reveals a new exciton pattern induced by the modified exchange coupling. Analysis of the exciton pattern exposes C2/c monoclinic symmetry in the high field phase of hematite. Taken together, these findings advance our understanding of iron-based materials under extreme conditions. [4pt] Collaborators include: X. S. Xu, P. Chen, Q. -C. Sun, T. V. Brinzari (Tennessee); S. McGill (NHMFL); J. De Groot, M. Angst, R. P. Hermann (Julich); A. D. Christianson, B. C. Sales, D. Mandrus (ORNL); A. P. Litvinchuk (Houston); J. -W. Kim (Ames); Z. Islam (Argonne); N. Lee, S. -W. Cheong

  16. Analytic Optimization of Near-Field Optical Chirality Enhancement

    Science.gov (United States)

    2017-01-01

    We present an analytic derivation for the enhancement of local optical chirality in the near field of plasmonic nanostructures by tuning the far-field polarization of external light. We illustrate the results by means of simulations with an achiral and a chiral nanostructure assembly and demonstrate that local optical chirality is significantly enhanced with respect to circular polarization in free space. The optimal external far-field polarizations are different from both circular and linear. Symmetry properties of the nanostructure can be exploited to determine whether the optimal far-field polarization is circular. Furthermore, the optimal far-field polarization depends on the frequency, which results in complex-shaped laser pulses for broadband optimization. PMID:28239617

  17. Optical properties of cluster plasma

    Energy Technology Data Exchange (ETDEWEB)

    Kishimoto, Yasuaki; Tajima, Toshiki [Japan Atomic Energy Research Inst., Neyagawa, Osaka (Japan). Kansai Research Establishment; Downer, M C

    1998-03-01

    It is shown that unlike a gas plasma or an electron plasma in a metal, an ionized clustered material (`cluster plasma`) permits propagation below the plasma cut-off of electromagnetic (EM) waves whose phase velocity is close to but below the speed of light. This results from the excitation of a plasma oscillation mode (and/or polarization mode) through the cluster surface which does not exist in usual gaseous plasma. The existence of this new optical mode, cluster mode, is confirmed via numerical simulation. (author)

  18. Effective Optical Properties of Plasmonic Nanocomposites

    Directory of Open Access Journals (Sweden)

    Christoph Etrich

    2014-01-01

    Full Text Available Plasmonic nanocomposites find many applications, such as nanometric coatings in emerging fields, such as optotronics, photovoltaics or integrated optics. To make use of their ability to affect light propagation in an unprecedented manner, plasmonic nanocomposites should consist of densely packed metallic nanoparticles. This causes a major challenge for their theoretical description, since the reliable assignment of effective optical properties with established effective medium theories is no longer possible. Established theories, e.g., the Maxwell-Garnett formalism, are only applicable for strongly diluted nanocomposites. This effective description, however, is a prerequisite to consider plasmonic nanocomposites in the design of optical devices. Here, we mitigate this problem and use full wave optical simulations to assign effective properties to plasmonic nanocomposites with filling fractions close to the percolation threshold. We show that these effective properties can be used to properly predict the optical action of functional devices that contain nanocomposites in their design. With this contribution we pave the way to consider plasmonic nanocomposites comparably to ordinary materials in the design of optical elements.

  19. Linear Optical Properties of Gold Colloid

    Directory of Open Access Journals (Sweden)

    Jingmin XIA

    2015-11-01

    Full Text Available Gold colloid was prepared by reducing HAuCl4·4H2O with Na3C6H5O7·2H2O. The morphology, size of gold nanoparticles and the optical property of colloid were characterized by transmission electron microscope and UV-Vis spectrophotometer, respectively. It shows that the gold nanoparticles are in the shape of spheres with diameters less than 8 nm, and the surface plasmon resonance absorption peak is located at about 438 nm. As the volume fraction of gold particles increases, the intensity of absorption peak strengthens. The optical property of gold colloid was analyzed by Maxwell-Garnett (MG effective medium theory in the company of Drude dispersion model. The results show that the matrix dielectric constant is a main factor, which influences the optical property of gold colloid.DOI: http://dx.doi.org/10.5755/j01.ms.21.4.9558

  20. Defined wetting properties of optical surfaces

    Science.gov (United States)

    Felde, Nadja; Coriand, Luisa; Schröder, Sven; Duparré, Angela; Tünnermann, Andreas

    2017-10-01

    Optical surfaces equipped with specific functional properties have attracted increasing importance over the last decades. In the light of cost reduction, hydrophobic self-cleaning behavior is aspired. On the other side, hydrophilic properties are interesting due to their anti-fog effect. It has become well known that such wetting states are significantly affected by the surface morphology. For optical surfaces, however, this fact poses a problem, as surface roughness can induce light scattering. The generation of optical surfaces with specific wetting properties, hence, requires a profound understanding of the relation between the wetting and the structural surface properties. Thus, our work concentrates on a reliable acquisition of roughness data over a wide spatial frequency range as well as on the comprehensive description of the wetting states, which is needed for the establishment of such correlations. We will present our advanced wetting analysis for nanorough optical surfaces, extended by a vibration-based procedure, which is mainly for understanding and tailoring the wetting behavior of various solid-liquid systems in research and industry. Utilizing the relationships between surface roughness and wetting, it will be demonstrated how different wetting states for hydrophobicity and hydrophilicity can be realized on optical surfaces with minimized scatter losses.

  1. Optical properties of opal photonic crystals

    Science.gov (United States)

    Eradat-Oskouei, Nayer

    2001-10-01

    geometry. Dramatic differences in the reflectivity spectra of two kinds of metallic structures, with network or cermet topologies, were observed. Bragg diffraction occurs from both topologies. In addition, highly interconnected metallic PC structures showed about one order of magnitude decrease in the effective plasma frequency. These properties may be used to create transparent metals. Coherent backscattering measurements showed a much larger optical mean free path for the metal-infiltrated opals compared to the skin depth of the metals. Chapter 5 deals with the enhancement and inhibition of the spontaneous emission in PCs. In addition, the effect of the PBG on the photo-induced absorption (PA) of a π-conjugated polymer, when the absorption band lies within the PBG, is investigated for the first time. Changes in the PA spectrum of a π-conjugated polymer, DOO-PPP, infiltrated in opals were observed that are probably influenced by the photonic stop-band. This dissertation ends with some suggestions in Chapter 6 for future experiments.

  2. Optical properties of low-dimensional materials

    CERN Document Server

    Ogawa, T

    1998-01-01

    This book surveys recent theoretical and experimental studies of optical properties of low-dimensional materials. As an extended version of Optical Properties of Low-Dimensional Materials (Volume 1, published in 1995 by World Scientific), Volume 2 covers a wide range of interesting low-dimensional materials including both inorganic and organic systems, such as disordered polymers, deformable molecular crystals, dilute magnetic semiconductors, SiGe/Si short-period superlattices, GaAs quantum wires, semiconductor microcavities, and photonic crystals. There are excellent review articles by promis

  3. Coupled nanopillar waveguides: optical properties and applications

    DEFF Research Database (Denmark)

    Chigrin, Dmitry N.; Zhukovsky, Sergei V.; Lavrinenko, Andrei

    2007-01-01

    , while guided modes dispersion is strongly affected by the waveguide structure. We present a systematic analysis of the optical properties of coupled nanopillar waveguides and discuss their possible applications for integrated optics. (C) 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim......In this paper we review basic properties of coupled periodic and aperiodic nanopillar waveguides. A coupled nanopillar waveguide consists of several rows of periodically or aperiodically placed dielectric rods (pillars). In such a waveguide, light confinement is due to the total internal reflection...

  4. Optical properties of metals by spectroscopic ellipsometry

    International Nuclear Information System (INIS)

    Arakawa, E.T.; Inagaki, T.; Williams, M.W.

    1979-01-01

    The use of spectroscopic ellipsometry for the accurate determination of the optical properties of liquid and solid metals is discussed and illustrated with previously published data for Li and Na. New data on liquid Sn and Hg from 0.6 to 3.7 eV are presented. Liquid Sn is Drude-like. The optical properties of Hg deviate from the Drude expressions, but simultaneous measurements of reflectance and ellipsometric parameters yield consistent results with no evidence for vectorial surface effects

  5. Optical design applications for enhanced illumination performance

    Science.gov (United States)

    Gilray, Carl; Lewin, Ian

    1995-08-01

    Nonimaging optical design techniques have been applied in the illumination industry for many years. Recently however, powerful software has been developed which allows accurate simulation and optimization of illumination devices. Wide experience has been obtained in using such design techniques for practical situations. These include automotive lighting where safety is of greatest importance, commercial lighting systems designed for energy efficiency, and numerous specialized applications. This presentation will discuss the performance requirements of a variety of illumination devices. It will further cover design methodology and present a variety of examples of practical applications for enhanced system performance.

  6. Enhanced energy storage in chaotic optical resonators

    KAUST Repository

    Liu, Changxu; Di Falco, Andrea; Molinari, Diego P.; Khan, Yasser; Ooi, Boon S.; Krauss, Thomas F.; Fratalocchi, Andrea

    2013-01-01

    Chaos is a phenomenon that occurs in many aspects of contemporary science. In classical dynamics, chaos is defined as a hypersensitivity to initial conditions. The presence of chaos is often unwanted, as it introduces unpredictability, which makes it difficult to predict or explain experimental results. Conversely, we demonstrate here how chaos can be used to enhance the ability of an optical resonator to store energy. We combine analytic theory with ab initio simulations and experiments in photonic-crystal resonators to show that a chaotic resonator can store six times more energy than its classical counterpart of the same volume. We explain the observed increase by considering the equipartition of energy among all degrees of freedom of the chaotic resonator (that is, the cavity modes) and discover a convergence of their lifetimes towards a single value. A compelling illustration of the theory is provided by enhanced absorption in deformed polystyrene microspheres. © 2013 Macmillan Publishers Limited. All rights reserved.

  7. Enhanced energy storage in chaotic optical resonators

    KAUST Repository

    Liu, Changxu

    2013-05-05

    Chaos is a phenomenon that occurs in many aspects of contemporary science. In classical dynamics, chaos is defined as a hypersensitivity to initial conditions. The presence of chaos is often unwanted, as it introduces unpredictability, which makes it difficult to predict or explain experimental results. Conversely, we demonstrate here how chaos can be used to enhance the ability of an optical resonator to store energy. We combine analytic theory with ab initio simulations and experiments in photonic-crystal resonators to show that a chaotic resonator can store six times more energy than its classical counterpart of the same volume. We explain the observed increase by considering the equipartition of energy among all degrees of freedom of the chaotic resonator (that is, the cavity modes) and discover a convergence of their lifetimes towards a single value. A compelling illustration of the theory is provided by enhanced absorption in deformed polystyrene microspheres. © 2013 Macmillan Publishers Limited. All rights reserved.

  8. Optical and electrochromic properties of Sn:WO3 cermets

    International Nuclear Information System (INIS)

    Ashrit, P.V.; Bader, G.; Girouard, F.E.; Truong, V.V.

    1989-01-01

    This paper discusses optical and electrochromic properties of Sn:WO 3 cermets deposited by alternate layer thermal deposition. These cermets exhibit electrical and optical behavior in the as deposited state. The inclusion of Sn in the WO 3 matrix enhances the Electrical conductivity of the system and renders them fairly transparent in the visible region. The electrochromic behavior of such systems is studied under both proton and Li + ion injection. The good conductivity and good transmission combined with good electrochromic characteristics of these systems indicate the possibility of utilizing this type of cermet for the dual role of transparent conductor (TC) and electrochromic (EC) layer

  9. Machine learning enhanced optical distance sensor

    Science.gov (United States)

    Amin, M. Junaid; Riza, N. A.

    2018-01-01

    Presented for the first time is a machine learning enhanced optical distance sensor. The distance sensor is based on our previously demonstrated distance measurement technique that uses an Electronically Controlled Variable Focus Lens (ECVFL) with a laser source to illuminate a target plane with a controlled optical beam spot. This spot with varying spot sizes is viewed by an off-axis camera and the spot size data is processed to compute the distance. In particular, proposed and demonstrated in this paper is the use of a regularized polynomial regression based supervised machine learning algorithm to enhance the accuracy of the operational sensor. The algorithm uses the acquired features and corresponding labels that are the actual target distance values to train a machine learning model. The optimized training model is trained over a 1000 mm (or 1 m) experimental target distance range. Using the machine learning algorithm produces a training set and testing set distance measurement errors of learning. Applications for the proposed sensor include industrial scenario distance sensing where target material specific training models can be generated to realize low <1% measurement error distance measurements.

  10. Complex yet translucent: the optical properties of sea ice

    International Nuclear Information System (INIS)

    Perovich, Donald K.

    2003-01-01

    Sea ice is a naturally occurring material with an intricate and highly variable structure consisting of ice platelets, brine pockets, air bubbles, and precipitated salt crystals. The optical properties of sea ice are directly dependent on this ice structure. Because sea ice is a material that exists at its salinity determined freezing point, its structure and optical properties are significantly affected by small changes in temperature. Understanding the interaction of sunlight with sea ice is important to a diverse array of scientific problems, including those in polar climatology. A key optical parameter for climatological studies is the albedo, the fraction of the incident sunlight that is reflected. The albedo of sea ice is quite sensitive to surface conditions. The presence of a snow cover enhances the albedo, while surface meltwater reduces the albedo. Radiative transfer in sea ice is a combination of absorption and scattering. Differences in the magnitude of sea ice optical properties are ascribable primarily to differences in scattering, while spectral variations are mainly a result of absorption. Physical changes that enhance scattering, such as the formation of air bubbles due to brine drainage, result in more light reflection and less transmission

  11. Some optical properties of the spiral inflector

    International Nuclear Information System (INIS)

    Toprek, Dragan; Subotic, Krunoslav

    1999-01-01

    This paper compares some optical properties of different spiral inflectors using the program CASINO. The electric field distribution in the inflectors has been numerically calculated from an electric potential map produced by the program RELAX3D. The magnetic field is assumed to be constant. We have also made an effort to minimize the inflector fringe field using the RELAX3D program. (author)

  12. Optical Properties of Semiconductor Quantum Dots

    NARCIS (Netherlands)

    Perinetti, U.

    2011-01-01

    This thesis presents different optical experiments performed on semiconductor quantum dots. These structures allow to confine a small number of electrons and holes to a tiny region of space, some nm across. The aim of this work was to study the basic properties of different types of quantum dots

  13. Optical properties of silver composite metamaterials

    Energy Technology Data Exchange (ETDEWEB)

    Orbons, S.M. [School of Physics, University of Melbourne, Victoria 3010 (Australia)]. E-mail: sorbons@ph.unimelb.edu.au; Freeman, D. [Centre for Ultrahigh-bandwidth Devices for Optical Systems, Laser Physics Centre, Australian National University, ACT 0200 (Australia); Luther-Davies, B. [Centre for Ultrahigh-bandwidth Devices for Optical Systems, Laser Physics Centre, Australian National University, ACT 0200 (Australia); Gibson, B.C. [Quantum Communications Victoria, School of Physics, University of Melbourne, Victoria 3010 (Australia); Huntington, S.T. [Quantum Communications Victoria, School of Physics, University of Melbourne, Victoria 3010 (Australia); Jamieson, D.N. [School of Physics, University of Melbourne, Victoria 3010 (Australia); Roberts, A. [School of Physics, University of Melbourne, Victoria 3010 (Australia)

    2007-05-15

    We present a computational and experimental study investigating the optical properties of nanoscale silver composite metamaterials fabricated by ion beam lithography. Both simulations and experimental results demonstrate high transmission efficiencies in the near infra-red through these devices. Implications for experimentally verifying the calculated near-field distributions of these materials are also discussed.

  14. Optical Properties of Nanoparticles and Nanocomposites

    CSIR Research Space (South Africa)

    Kumbhakar, P

    2014-01-01

    Full Text Available of ceria nanoparticles and degradation of Congo red (CR) dye under the visible light irradiation. We are very much happy to note the research progress on the techniques of synthesis, characterization, and optical properties of nanostructured materials. Also...

  15. Modifications of optical properties with ceramic coatings

    International Nuclear Information System (INIS)

    Besmann, T.M.; Abdel-Latif, A.I.

    1990-01-01

    Coatings of ceramic materials that exhibited high thermal absorptivities and emissivities were chemical vapor deposited on graphite and refractory metals. In this paper the coatings prepared were SiC and B 4 C, and the substrates used were graphite, molybdenum, titanium, and Nb-1Zr. The coatings are characterized with regard to adherence, optical properties, and response to potential harsh environments

  16. Enhancement of accuracy in shape sensing of surgical needles using optical frequency domain reflectometry in optical fibers.

    Science.gov (United States)

    Parent, Francois; Loranger, Sebastien; Mandal, Koushik Kanti; Iezzi, Victor Lambin; Lapointe, Jerome; Boisvert, Jean-Sébastien; Baiad, Mohamed Diaa; Kadoury, Samuel; Kashyap, Raman

    2017-04-01

    We demonstrate a novel approach to enhance the precision of surgical needle shape tracking based on distributed strain sensing using optical frequency domain reflectometry (OFDR). The precision enhancement is provided by using optical fibers with high scattering properties. Shape tracking of surgical tools using strain sensing properties of optical fibers has seen increased attention in recent years. Most of the investigations made in this field use fiber Bragg gratings (FBG), which can be used as discrete or quasi-distributed strain sensors. By using a truly distributed sensing approach (OFDR), preliminary results show that the attainable accuracy is comparable to accuracies reported in the literature using FBG sensors for tracking applications (~1mm). We propose a technique that enhanced our accuracy by 47% using UV exposed fibers, which have higher light scattering compared to un-exposed standard single mode fibers. Improving the experimental setup will enhance the accuracy provided by shape tracking using OFDR and will contribute significantly to clinical applications.

  17. Characterizing the optical properties of human brain tissue with high numerical aperture optical coherence tomography.

    Science.gov (United States)

    Wang, Hui; Magnain, Caroline; Sakadžić, Sava; Fischl, Bruce; Boas, David A

    2017-12-01

    Quantification of tissue optical properties with optical coherence tomography (OCT) has proven to be useful in evaluating structural characteristics and pathological changes. Previous studies primarily used an exponential model to analyze low numerical aperture (NA) OCT measurements and obtain the total attenuation coefficient for biological tissue. In this study, we develop a systematic method that includes the confocal parameter for modeling the depth profiles of high NA OCT, when the confocal parameter cannot be ignored. This approach enables us to quantify tissue optical properties with higher lateral resolution. The model parameter predictions for the scattering coefficients were tested with calibrated microsphere phantoms. The application of the model to human brain tissue demonstrates that the scattering and back-scattering coefficients each provide unique information, allowing us to differentially identify laminar structures in primary visual cortex and distinguish various nuclei in the midbrain. The combination of the two optical properties greatly enhances the power of OCT to distinguish intricate structures in the human brain beyond what is achievable with measured OCT intensity information alone, and therefore has the potential to enable objective evaluation of normal brain structure as well as pathological conditions in brain diseases. These results represent a promising step for enabling the quantification of tissue optical properties from high NA OCT.

  18. Quantum optical properties in plasmonic systems

    Energy Technology Data Exchange (ETDEWEB)

    Ooi, C. H. Raymond [Department of Physics, University of Malaya, 50603, Kuala Lumpur (Malaysia)

    2015-04-24

    Plasmonic metallic particle (MP) can affect the optical properties of a quantum system (QS) in a remarkable way. We develop a general quantum nonlinear formalism with exact vectorial description for the scattered photons by the QS. The formalism enables us to study the variations of the dielectric function and photon spectrum of the QS with the particle distance between QS and MP, exciting laser direction, polarization and phase in the presence of surface plasmon resonance (SPR) in the MP. The quantum formalism also serves as a powerful tool for studying the effects of these parameters on the nonclassical properties of the scattered photons. The plasmonic effect of nanoparticles has promising possibilities as it provides a new way for manipulating quantum optical properties of light in nanophotonic systems.

  19. Human tissue optical properties measurements and light propagation modelling

    CSIR Research Space (South Africa)

    Dam, JS

    2006-07-01

    Full Text Available Biomedical Optics is the study of the optical properties of living biological material, especially its scattering and absorption characteristics, and their significance to light propagation within the material. Determination of tissue optical...

  20. Amine-Based Passivating Materials for Enhanced Optical Properties and Performance of Organic-Inorganic Perovskites in Light-Emitting Diodes.

    Science.gov (United States)

    Lee, Seungjin; Park, Jong Hyun; Lee, Bo Ram; Jung, Eui Dae; Yu, Jae Choul; Di Nuzzo, Daniele; Friend, Richard H; Song, Myoung Hoon

    2017-04-20

    The use of hybrid organic-inorganic perovskites in optoelectronic applications are attracting an interest because of their outstanding characteristics, which enable a remarkable enhancement of device efficiency. However, solution-processed perovskite crystals unavoidably contain defect sites that cause hysteresis in perovskite solar cells (PeSCs) and blinking in perovskite light-emitting diodes (PeLEDs). Here, we report significant beneficial effects using a new treatment based on amine-based passivating materials (APMs) to passivate the defect sites of methylammonium lead tribromide (MAPbBr 3 ) through coordinate bonding between the nitrogen atoms and undercoordinated lead ions. This treatment greatly enhanced the PeLED's efficiency, with an external quantum efficiency (EQE) of 6.2%, enhanced photoluminescence (PL), a lower threshold for amplified spontaneous emission (ASE), a longer PL lifetime, and enhanced device stability. Using confocal microscopy, we observed the cessation of PL blinking in perovskite films treated with ethylenediamine (EDA) due to passivation of the defect sites in the MAPbBr 3 .

  1. Optical properties of stabilized copper nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Mohindroo, Jeevan Jyoti, E-mail: jjmdav@gmail.com [Punjab Technical University, Kapurthala Punjab (India); Department of Chemistry, DAV College, Amritsar, Punjab India (India); Garg, Umesh Kumar, E-mail: Umeshkgarg@gmail.com [Punjab Technical University, Kapurthala Punjab (India); Guru Teg Bahadur Khalsa College of IT, Malout, Punjab (India); Sharma, Anshul Kumar [Department of Physics, Guru Nanak Dev University, Amritsar 143005 (India)

    2016-05-06

    Optical studies involving calculation of Band Gap of the synthesized copper nanoparticles were carried out in the wavelength range of 500 to 650 nm at room temperature, the particles showed high absorption at 550 nm indicating their good absorptive properties. In this method water is used as the medium for reduction of copper ions in to copper Nanoparticles the stabilization of copper Nanoparticles was studied with starch both as a reductant and stabilizer,. The reaction mixture was heated using a kitchen microwave for about 5 minutes to attain the required temp for the reaction. The pH of the solution was adjusted to alkaline using 5% solution of NaOH. Formation of Copper Nanoparticles was indicated by change in color of the solution from blue to yellowish black which is supported by the UV absorption at 570 nm.the synthesized particles were washed with water and alcohol. The optical properties depend upon absorption of radiations which in turn depends upon ratio of electrons and holes present in the material and also on the shape of the nanoparticles. In the present investigation it was observed that optical absorption increases with increase in particle size. The optical band gap for the Nanoparticles was obtained from plots between hv vs. (αhv){sup 2} and hv vs. (αhv){sup 1/2}. The value of Band gap came out to be around 1.98–2.02 eV which is in close agreement with the earlier reported values.

  2. Optical properties of cells with melanin

    Science.gov (United States)

    Rohde, Barukh; Coats, Israel; Krueger, James; Gareau, Dan

    2014-02-01

    The optical properties of pigmented lesions have been studied using diffuse reflectance spectroscopy in a noninvasive configuration on optically thick samples such as skin in vivo. However, it is difficult to un-mix the effects of absorption and scattering with diffuse reflectance spectroscopy techniques due to the complex anatomical distributions of absorbing and scattering biomolecules. We present a device and technique that enables absorption and scattering measurements of tissue volumes much smaller than the optical mean-free path. Because these measurements are taken on fresh-frozen sections, they are direct measurements of the optical properties of tissue, albeit in a different hydration state than in vivo tissue. Our results on lesions from 20 patients including melanomas and nevi show the absorption spectrum of melanin in melanocytes and basal keratinocytes. Our samples consisted of fresh frozen sections that were unstained. Fitting the spectrum as an exponential decay between 500 and 1100 nm [mua = A*exp(-B*(lambda-C)) + D], we report on the fit parameters of and their variation due to biological heterogeneity as A = 4.20e4 +/- 1.57e5 [1/cm], B = 4.57e-3 +/- 1.62e-3 [1/nm], C = 210 +/- 510 [nm] , D = 613 +/- 534 [1/cm]. The variability in these results is likely due to highly heterogeneous distributions of eumelanin and pheomelanin.

  3. Broadband optical characterization of material properties

    DEFF Research Database (Denmark)

    Nielsen, Otto Højager Attermann

    the applicability of optical techniques for this purpose, the fermentation of milk into yogurt has been used as a model system. Studies have been conducted on commercially available products, but also of on-line measurement of the fermentation process. The second process is from the aquaculture industry...... reports on the design and operation of the different measurement techniques together with the necessary theoretical background for the industrial applications. For the purpose of milk fermentation this work has demonstrated that the reduced scattering properties of milk change significantly throughout...... the fermentation process. It has also been shown that the optical inspection methods sense changes to structural properties before any are detected by traditional mechanical rheology. Finally, the developed hyperspectral imaging system was used to quantify the content of astaxanthin in fish feed, and performed...

  4. Quantitative contrast-enhanced optical coherence tomography

    Energy Technology Data Exchange (ETDEWEB)

    Winetraub, Yonatan; SoRelle, Elliott D. [Molecular Imaging Program at Stanford, Stanford University, 299 Campus Drive, Stanford, California 94305 (United States); Bio-X Program, Stanford University, 299 Campus Drive, Stanford, California 94305 (United States); Biophysics Program, Stanford University, 299 Campus Drive, Stanford, California 94305 (United States); Department of Structural Biology, Stanford University, 299 Campus Drive, Stanford, California 94305 (United States); Liba, Orly [Molecular Imaging Program at Stanford, Stanford University, 299 Campus Drive, Stanford, California 94305 (United States); Bio-X Program, Stanford University, 299 Campus Drive, Stanford, California 94305 (United States); Department of Structural Biology, Stanford University, 299 Campus Drive, Stanford, California 94305 (United States); Department of Electrical Engineering, Stanford University, 299 Campus Drive, Stanford, California 94305 (United States); Zerda, Adam de la [Molecular Imaging Program at Stanford, Stanford University, 299 Campus Drive, Stanford, California 94305 (United States); Bio-X Program, Stanford University, 299 Campus Drive, Stanford, California 94305 (United States); Biophysics Program, Stanford University, 299 Campus Drive, Stanford, California 94305 (United States); Department of Structural Biology, Stanford University, 299 Campus Drive, Stanford, California 94305 (United States); Department of Electrical Engineering, Stanford University, 299 Campus Drive, Stanford, California 94305 (United States)

    2016-01-11

    We have developed a model to accurately quantify the signals produced by exogenous scattering agents used for contrast-enhanced Optical Coherence Tomography (OCT). This model predicts distinct concentration-dependent signal trends that arise from the underlying physics of OCT detection. Accordingly, we show that real scattering particles can be described as simplified ideal scatterers with modified scattering intensity and concentration. The relation between OCT signal and particle concentration is approximately linear at concentrations lower than 0.8 particle per imaging voxel. However, at higher concentrations, interference effects cause signal to increase with a square root dependence on the number of particles within a voxel. Finally, high particle concentrations cause enough light attenuation to saturate the detected signal. Predictions were validated by comparison with measured OCT signals from gold nanorods (GNRs) prepared in water at concentrations ranging over five orders of magnitude (50 fM to 5 nM). In addition, we validated that our model accurately predicts the signal responses of GNRs in highly heterogeneous scattering environments including whole blood and living animals. By enabling particle quantification, this work provides a valuable tool for current and future contrast-enhanced in vivo OCT studies. More generally, the model described herein may inform the interpretation of detected signals in modalities that rely on coherence-based detection or are susceptible to interference effects.

  5. Optical properties of nasal septum cartilage

    Science.gov (United States)

    Bagratashvili, Nodar V.; Sviridov, Alexander P.; Sobol, Emil N.; Kitai, Moishe S.

    1998-05-01

    Optical parameters (scattering coefficient s, absorption coefficient k and scattering anisotropy coefficient g) of hyaline cartilage were studied for the first time. Optical properties of human and pig nasal septum cartilage, and of bovine ear cartilage were examined using a spectrophotometer with an integrating sphere, and an Optical Multi-Channel Analyser. We measured total transmission Tt, total reflection Rt, and on-axis transmission Ta for light propagating through cartilage sample, over the visible spectral range (14000 - 28000 cm-1). It is shown that transmission and reflection spectra of human, pig and bovine cartilage are rather similar. It allows us to conclude that the pig cartilage can be used for in-vivo studies instead of human cartilage. The data obtained were treated by means of the one-dimensional diffusion approximation solution of the optical transport equation. We have found scattering coefficient s, absorption coefficient k and scattering anisotropy coefficient g by the iterative comparison of measured and calculated Tt, Rt and Ta values for human and pig cartilage. We found, in particular, that for 500 nm irradiation s equals 37,6 plus or minus 3.5 cm-1, g equals 0,56 plus or minus 0.05, k approximately equals 0,5 plus or minus 0.3 cm-1. The above data were used in Monte Carlo simulation for spatial intensity profile of light scattered by a cartilage sample. The computed profile was very similar to the profile measured using an Optical Multi-Channel Analyzer (OMA).

  6. Magneto-optic properties and optical parameter of thin MnCo films

    Directory of Open Access Journals (Sweden)

    E Attaran Kakhki

    2009-09-01

    Full Text Available Having precise hysterics loop of thin ferroelectric and ferromagnetic layers for optical switching and optical storages are important. A hysterieses loop can be achieved from a phenomenon call the magneto-optic effect. The magneto-optic effect is the rotation of a linear polarized electromagnetic wave propagated through a ferromagnetic medium. When light is transmitted through a layer of magnetic material the result is called the Faraday effects and in the reflection mode Kerr effect. In the present work we prepared a thin layer of MnxCo3-xO4 (0≤ x ≤ 1 and a binary form of MnO/Co3O4 by the spray pyrolysis method. The films have been characterized by a special set up of magneto-optic hysterics loop plotter containing a polarized He- Ne laser beam and a special electronic circuit. Faraday rotation were measured for these films by hysterics loop plotter and their optical properties were also obtained by spatial software designed for this purpose according to Swane Poel theoretical method. The measurements show that the samples at diluted Mn study has are ferromagnetic and the magneto-optic rotation show a good enhance respect to the single Co layers. Also, the study has shown that the MnCo oxide layer have two different energy gaps and by increasing of Mn this energy decreases and fall to 0.13 eV.

  7. True resolution enhancement for optical spectroscopy

    Science.gov (United States)

    Cooper, Justin T.; Oleske, Jeffrey B.

    2018-02-01

    Resolving spectrally adjacent peaks is important for techniques, such as tracking small shifts in Raman or fluorescence spectra, quantifying pharmaceutical polymorph ratios, or molecular orientation studies. Thus, suitable spectral resolution is a vital consideration when designing most spectroscopic systems. Most parameters that influence spectral resolution are fixed for a given system (spectrometer length, grating groove density, excitation source, CCD pixel size, etc.). Inflexible systems are non-problematic if the spectrometer is dedicated for a single purpose; however, these specifications cannot be optimized for different applications with wider range resolution requirements. Data processing techniques, including peak fitting, partial least squares, or principal component analysis, are typically used to achieve sub-optical resolution information. These techniques can be plagued by spectral artifacts introduced by post-processing as well as the subjective implementation of statistical parameters. TruRes™, from Andor Technology, uses an innovative optical means to greatly improve and expand the range of spectral resolutions accessible on a single setup. True spectral resolution enhancement of >30% is achieved without mathematical spectral alteration, dataprocessing, or spectrometer component changes. Discreet characteristic spectral lines from Laser-Induced Breakdown Spectroscopy (LIBS) and atomic calibration sources are now fully resolved from spectrally-adjacent peaks under otherwise identical configuration. TruRes™ has added advantage of increasing the spectral resolution without sacrificing bandpass. Using TruRes™ the Kymera 328i resolution can approach that of a 500 mm focal spectrometer. Furthermore, the bandpass of a 500 mm spectrograph with would be 50% narrower than the Kymera 328i with all other spectrometer components constant. However, the Kymera 328i with TruRes™ is able to preserve a 50% wider bandpass.

  8. Relevant optical properties for direct restorative materials.

    Science.gov (United States)

    Pecho, Oscar E; Ghinea, Razvan; do Amaral, Erika A Navarro; Cardona, Juan C; Della Bona, Alvaro; Pérez, María M

    2016-05-01

    To evaluate relevant optical properties of esthetic direct restorative materials focusing on whitened and translucent shades. Enamel (E), body (B), dentin (D), translucent (T) and whitened (Wh) shades for E (WhE) and B (WhB) from a restorative system (Filtek Supreme XTE, 3M ESPE) were evaluated. Samples (1 mm thick) were prepared. Spectral reflectance (R%) and color coordinates (L*, a*, b*, C* and h°) were measured against black and white backgrounds, using a spectroradiometer, in a viewing booth, with CIE D65 illuminant and d/0° geometry. Scattering (S) and absorption (K) coefficients and transmittance (T%) were calculated using Kubelka-Munk's equations. Translucency (TP) and opalescence (OP) parameters and whiteness index (W*) were obtained from differences of CIELAB color coordinates. R%, S, K and T% curves from all shades were compared using VAF (Variance Accounting For) coefficient with Cauchy-Schwarz inequality. Color coordinates and optical parameters were statistically analyzed using one-way ANOVA, Tukey's test with Bonferroni correction (α=0.0007). Spectral behavior of R% and S were different for T shades. In addition, T shades showed the lowest R%, S and K values, as well as the highest T%, TP an OP values. In most cases, WhB shades showed different color and optical properties (including TP and W*) than their corresponding B shades. WhE shades showed similar mean W* values and higher mean T% and TP values than E shades. When using whitened or translucent composites, the final color is influenced not only by the intraoral background but also by the color and optical properties of multilayers used in the esthetic restoration. Copyright © 2016 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  9. Subnanometric stabilization of plasmon-enhanced optical microscopy

    International Nuclear Information System (INIS)

    Yano, Taka-aki; Ichimura, Taro; Kuwahara, Shota; Verma, Prabhat; Kawata, Satoshi

    2012-01-01

    We have demonstrated subnanometric stabilization of tip-enhanced optical microscopy under ambient condition. Time-dependent thermal drift of a plasmonic metallic tip was optically sensed at subnanometer scale, and was compensated in real-time. In addition, mechanically induced displacement of the tip, which usually occurs when the amount of tip-applied force varies, was also compensated in situ. The stabilization of tip-enhanced optical microscopy enables us to perform long-time and robust measurement without any degradation of optical signal, resulting in true nanometric optical imaging with high reproducibility and high precision. The technique presented is applicable for AFM-based nanoindentation with subnanometric precision. (paper)

  10. Enhanced Stability of Gold Magnetic Nanoparticles with Poly(4-styrenesulfonic acid-co-maleic acid): Tailored Optical Properties for Protein Detection

    Science.gov (United States)

    Zhang, Xiaomei; Zhang, Qinlu; Ma, Ting; Liu, Qian; Wu, Songdi; Hua, Kai; Zhang, Chao; Chen, Mingwei; Cui, Yali

    2017-09-01

    Gold magnetic nanoparticles (GoldMag) have attracted great attention due to their unique physical and chemical performances combining those of individual Fe3O4 and Au nanoparticles. Coating GoldMag with polymers not only increases the stability of the composite particles suspended in buffer but also plays a key role for establishing point-of-care optical tests for clinically relevant biomolecules. In the present paper, poly(4-styrenesulfonic acid-co-maleic acid) (PSS-MA), a negatively charged polyelectrolyte with both sulfonate and carboxylate anionic groups, was used to coat the positively charged GoldMag (30 nm) surface. The PSS-MA-coated GoldMag complex has a stable plasmon resonance adsorption peak at 544 nm. A pair of anti-D-dimer antibodies has been coupled on this GoldMag composite nanoparticle surface, and a target protein, D-dimer was detected, in the range of 0.3-6 μg/mL. The shift of the characteristic peak, caused by the assembly of GoldMag due to the formation of D-dimer-antibody sandwich bridges, allowed the detection.

  11. Optical properties of quasiperiodically arranged semiconductor nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Werchner, Marco

    2009-12-18

    This work consists of two parts which are entitled ''One-Dimensional Resonant Fibonacci Quasicrystals'' and ''Resonant Tunneling of Light in Silicon Nanostructures''. A microscopic theory has been applied to investigate the optical properties of the respective semiconductor nanostructures. The studied one-dimensional resonant Fibonacci quasicrystals consist of GaAs quantum wells (QW) that are separated by either a large spacer L or a small one S. These spacers are arranged according to the Fibonacci sequence LSLLSLSL.. The average spacing satisfies a generalized Bragg condition with respect to the 1s-exciton resonance of the QWs. A theory, that makes use of the transfer-matrix method and that allows for the microscopic description of many-body effects such as excitation-induced dephasing caused by the Coulomb scattering of carriers, has been applied to compute the optical spectra of such structures. A pronounced sharp reflectivity minimum is found in the vicinity of the heavy-hole resonance both in the measured as well as in the calculated linear 54-QW spectra. Specifically, the influence of the carrier density, of the QW arrangement, of a detuning away from the exact Bragg condition, of the average spacing as well as of the ratio of the optical path lengths of the large and small spacers L and S, respectively, and of the QW number on the optical properties of the samples have been studied. Additionally, self-similarity among reflection spectra corresponding to different QW numbers that exceed a Fibonacci number by one is observed, which identifies certain spectral features as true fingerprints of the Fibonacci spacing. In the second part, resonant tunneling of light in stacked structures consisting of alternating parallel layers of silicon and air have been studied theoretically.Light may tunnel through the air barrier due to the existence of evanescent waves inside the air layers if the neighboring silicon layer is close

  12. Optical properties of high-Tc superconductors

    International Nuclear Information System (INIS)

    Aspnes, D.E.; Kelly, M.K.

    1989-01-01

    The authors summarize the present status of optical spectroscopy of high-T c superconductors. The optical properties of these materials resemble those of the more common transition metal oxides except for being highly anisotropic in the infrared (IR). This large IR anisotrophy and a need to rely solely on reflectance techniques has hindered progress in obtaining accurate IR data and interpreting these data in terms of microscopic mechanisms. However, experimental consistency is now being approached with single-crystal samples, although interpretations of these data remain controversial and an unequivocal demonstration of a superconducting gap structure has not yet been achieved. The mid IR exhibits an absorption band whose systematics are neither well established nor understood. The situation in the visible-near-ultraviolet (V-NUV) is better, partly because of greatly reduced optical anisotropy and the availability of alternative measurement techniques that are not strongly affected by the lower optical quality of sintered material. As polycrystalline, sintered samples can be prepared relatively easily over wide ranges of composition, doping, and chemical substitution, most work on studying the chemical systematics of these materials has been done in this spectral range and some of the structure that appears here has been positively identified

  13. Resonance-enhanced optical forces between coupled photonic crystal slabs.

    Science.gov (United States)

    Liu, Victor; Povinelli, Michelle; Fan, Shanhui

    2009-11-23

    The behaviors of lateral and normal optical forces between coupled photonic crystal slabs are analyzed. We show that the optical force is periodic with displacement, resulting in stable and unstable equilibrium positions. Moreover, the forces are strongly enhanced by guided resonances of the coupled slabs. Such enhancement is particularly prominent near dark states of the system, and the enhancement effect is strongly dependent on the types of guided resonances involved. These structures lead to enhancement of light-induced pressure over larger areas, in a configuration that is directly accessible to externally incident, free-space optical beams.

  14. Structural, optical and thermal properties of nanoporous aluminum

    International Nuclear Information System (INIS)

    Ghrib, Taher

    2015-01-01

    Highlights: • A simple electrochemical technique is presented and used to manufacture a porous aluminum layer. • Manufactured pores of 40 nm diameter and 200 nm depth are filled by nanocrystal of silicon and graphite. • Dimensions of pores increase with the anodization current which ameliorate the optical and thermal properties. • A new thermal method is presented which permit to determine the pores density and the layer thickness. • All properties show that the manufactured material can be used with success in solar cells. - Abstract: In this work the structural, thermal and optical properties of porous aluminum thin film formed with various intensities of anodization current in sulfuric acid are highlighted. The obtained pores at the surface are filled by sprayed graphite and nanocrystalline silicon (nc-Si) thin films deposited by plasma enhancement chemical vapor deposition (PECVD) which the role is to improve its optical and thermal absorption giving a structure of an assembly of three different media such as deposited thin layer (graphite or silicon)/(porous aluminum layer filled with the deposited layer)/(Al sample). The effect of anodization current on the microstructure of porous aluminum and the effect of the deposited layer were systematically studied by atomic force microscopy (AFM), transmission electron microscopy (TEM) and Raman spectroscopy. The thermal properties such as the thermal conductivity (K) and thermal diffusivity (D) are determined by the photothermal deflection (PTD) technique which is a non destructive technique. Based on this full characterization, it is demonstrated that the thermal and optical characteristics of these films are directly correlated to their micro-structural properties

  15. Measuring Mechanical Properties Of Optical Glasses

    Science.gov (United States)

    Tucker, Dennis S.; Nichols, Ronald L.

    1989-01-01

    Report discusses mechanical tests measuring parameters of strength and fracture mechanics of optical glasses. To obtain required tables of mechanical properties of each glass of interest, both initial-strength and delayed-fracture techniques used. Modulus of rupture measured by well-known four-point bending method. Initial bending strength measured by lesser-known double-ring method, in which disk of glass supported on one face near edge by larger ring and pressed on its other face by smaller concentric ring. Method maximizes stress near center, making it more likely specimen fractures there, and thereby suppresses edge effects. Data from tests used to predict reliabilities and lifetimes of glass optical components of several proposed spaceborne instruments.

  16. Optical Properties of Bismuth Tellurite Based Glass

    Directory of Open Access Journals (Sweden)

    Hooi Ming Oo

    2012-04-01

    Full Text Available A series of binary tellurite based glasses (Bi2O3x (TeO2100−x was prepared by melt quenching method. The density, molar volume and refractive index increase when bismuth ions Bi3+ increase, this is due to the increased polarization of the ions Bi3+ and the enhanced formation of non-bridging oxygen (NBO. The Fourier transform infrared spectroscopy (FTIR results show the bonding of the glass sample and the optical band gap, Eopt decreases while the refractive index increases when the ion Bi3+ content increases.

  17. Optical Properties of Bismuth Tellurite Based Glass

    Science.gov (United States)

    Oo, Hooi Ming; Mohamed-Kamari, Halimah; Wan-Yusoff, Wan Mohd Daud

    2012-01-01

    A series of binary tellurite based glasses (Bi2O3)x (TeO2)100−x was prepared by melt quenching method. The density, molar volume and refractive index increase when bismuth ions Bi3+ increase, this is due to the increased polarization of the ions Bi3+ and the enhanced formation of non-bridging oxygen (NBO). The Fourier transform infrared spectroscopy (FTIR) results show the bonding of the glass sample and the optical band gap, Eopt decreases while the refractive index increases when the ion Bi3+ content increases. PMID:22605999

  18. Optical and luminescence properties of hydrogenated amorphous carbon

    International Nuclear Information System (INIS)

    Rusli

    1996-03-01

    In this thesis, the optical and luminescence properties of hydrogenated amorphous carbon(a - C:H) thin films deposited using a Plasma Enhanced Chemical Vapour Deposition (PECVD) system are studied. A photoluminescence (PL) measuring system with a wavelength range of 300nm to 900nm, used for the above study, has been set up as a main part of the research. Firstly, a simple yet powerful method developed to solve for the optical constants and thickness of a - C : H deposited on Si is presented. This is followed by an investigation into the optical properties of band gap modulated a - C : H thin films superlattice structures. a - C : H films, obtained from a wide range of deposition conditions, are then characterised in terms of their optical absorption, infrared absorption, Raman scattering, fraction of sp 2 to sp 3 bondings and unpaired electron spin density. Their PL characteristics, such as the peak emission energy, spectral bandwidth, quantum efficiency, fatigue and polarisation memory are investigated in relation to their microstructure. The results, taken together with those obtained from photoconductivity study and electric field quenching of PL, are used to understand the origin of the strong PL in a - C : H. Preliminary work on a - C : H electroluminescent celbis also presented. (author)

  19. Optical properties of GaAs

    International Nuclear Information System (INIS)

    Akinlami, J. O.; Ashamu, A. O.

    2013-01-01

    We have investigated the optical properties of gallium arsenide (GaAs) in the photon energy range 0.6–6.0 eV. We obtained a refractive index which has a maximum value of 5.0 at a photon energy of 3.1 eV; an extinction coefficient which has a maximum value of 4.2 at a photon energy of 5.0 eV; the dielectric constant, the real part of the complex dielectric constant has a maximum value of 24 at a photon energy of 2.8 eV and the imaginary part of the complex dielectric constant has a maximum value of 26.0 at a photon energy of 4.8 eV; the transmittance which has a maximum value of 0.22 at a photon energy of 4.0 eV; the absorption coefficient which has a maximum value of 0.22 × 10 8 m −1 at a photon energy of 4.8 eV, the reflectance which has a maximum value of 0.68 at 5.2eV; the reflection coefficient which has a maximum value of 0.82 at a photon energy of 5.2 eV; the real part of optical conductivity has a maximum value of 14.2 × 10 15 at 4.8 eV and the imaginary part of the optical conductivity has a maximum value of 6.8 × 10 15 at 5.0 eV. The values obtained for the optical properties of GaAs are in good agreement with other results. (semiconductor physics)

  20. Optical manipulation and catalytic activity enhanced by surface plasmon effect

    Science.gov (United States)

    Zou, Ningmu; Min, Jiang; Jiao, Wenxiang; Wang, Guanghui

    2017-02-01

    For optical manipulation, a nano-optical conveyor belt consisting of an array of gold plasmonic non-concentric nano-rings (PNNRs) is demonstrated for the realization of trapping and unidirectional transportation of nanoparticles by polarization rotation of excitation beam. These hot spots of an asymmetric plasmonic nanostructure are polarization dependent, therefore, one can use the incident polarization state to manipulate the trapped targets. Trapped particles could be transferred between adjacent PNNRs in a given direction just by rotating the polarization of incident beam due to unbalanced potential. The angular dependent distribution of electric field around PNNR has been solved using the three- dimensional finite-difference time-domain (FDTD) technique. For optical enhanced catalytic activity, the spectral properties of dimers of Au nanorod-Au nanorod nanostructures under the excitation of 532nm photons have been investigated. With a super-resolution catalytic mapping technique, we identified the existence of "hot spot" in terms of catalytic reactivity at the gap region within the twined plasmonic nanostructure. Also, FDTD calculation has revealed an intrinsic correlation between hot electron transfer.

  1. Optical properties of the semiconductor quantum structure

    International Nuclear Information System (INIS)

    Haratizadeh, H.; Holtz, P.O.; Monemar, B.; Karlsoon, K.F.; Moskalenko, E.S.; Amano, H.; Akasaki, I.; Schoenfeld, W.V.; Garcia, J.M.; Petroff, P.M.

    2004-01-01

    Optical properties of the quantum structures have been discussed with emphasize of the AlGaN/GaN multiple quantum wells and InAs/GaAs quantum dot structures. We report on a detailed study of low temperature photoluminescence in Al 0 .07Ga 0 .93 N/GaN multiple quantum wells. The structures were nominally undoped multiple quantum well grown on sapphire substrate. The structure from discrete well width variations is here resolved in photoluminescence spectra. The results demonstrate that the theoretically estimated fields in this work are consistent with the experimental spectra

  2. Optical properties of graphene nanoflakes: Shape matters.

    Science.gov (United States)

    Mansilla Wettstein, Candela; Bonafé, Franco P; Oviedo, M Belén; Sánchez, Cristián G

    2016-06-14

    In recent years there has been significant debate on whether the edge type of graphene nanoflakes (GNFs) or graphene quantum dots (GQDs) are relevant for their electronic structure, thermal stability, and optical properties. Using computer simulations, we have proven that there is a fundamental difference in the absorption spectra between samples of the same shape, similar size but different edge type, namely, armchair or zigzag edges. These can be explained by the presence of electronic structures near the Fermi level which are localized on the edges. These features are also evident from the dependence of band gap on the GNF size, which shows three very distinct trends for different shapes and edge geometries.

  3. Optical properties of graphene nanoflakes: Shape matters

    Energy Technology Data Exchange (ETDEWEB)

    Mansilla Wettstein, Candela; Bonafé, Franco P.; Sánchez, Cristián G., E-mail: cgsanchez@fcq.unc.edu.ar [Instituto de Investigaciones Fisicoquímicas de Córdoba, Consejo Nacional de Investigaciones Científicas y Técnicas (INFIQC - CONICET), Departamento de Matemática y Física, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Ciudad Universitaria, Córdoba X5000HUA (Argentina); Oviedo, M. Belén [Department of Chemical & Environmental Engineering and Materials Science and Engineering Program, University of California, Riverside, California 92521 (United States)

    2016-06-14

    In recent years there has been significant debate on whether the edge type of graphene nanoflakes (GNFs) or graphene quantum dots (GQDs) are relevant for their electronic structure, thermal stability, and optical properties. Using computer simulations, we have proven that there is a fundamental difference in the absorption spectra between samples of the same shape, similar size but different edge type, namely, armchair or zigzag edges. These can be explained by the presence of electronic structures near the Fermi level which are localized on the edges. These features are also evident from the dependence of band gap on the GNF size, which shows three very distinct trends for different shapes and edge geometries.

  4. Optical Properties and Immunoassay Applications of Noble Metal Nanoparticles

    International Nuclear Information System (INIS)

    Zhu, S.; Zhou, W.

    2010-01-01

    Noble metal, especially gold (Au) and silver (Ag) nanoparticles exhibit unique and tunable optical properties on account of their surface plasmon resonance (SPR). In this paper, we mainly discussed the theory background of the enhanced optical properties of noble metal nanoparticles. Mie theory, transfer matrix method, discrete dipole approximation (DDA) method, and finite-difference time domain (FDTD) method applied brute-force computational methods for different nanoparticles optical properties. Some important nanostructure fabrication technologies such as nanosphere lithography (NSL) and focused ion beam (FIB) are also introduced in this paper. Moreover, these fabricated nanostructures are used in the plasmonic sensing fields. The binding signal between the antibody and antigen, amyloid-derived diffusible ligands (ADDLs)-potential Alzheimer's disease (AD) biomarkers, and staphylococcal enterotoxin B (SEB) in nano-Moore per liter (nM) concentration level are detected by our designed nanobiosensor. They have many potential applications in the biosensor, environment protection, food security, and medicine safety for health, and so forth, fields.

  5. Characterizing and Understanding Aerosol Optical Properties: CARES - Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Cappa, Christopher D [Univ. of California, Davis, CA (United States); Atkinson, Dean B [Portland State Univ., Portland, OR (United States)

    2017-12-17

    The scientific focus of this study was to use ambient measurements to develop new insights into the understanding of the direct radiative forcing by atmospheric aerosol particles. The study used data collected by the PI’s and others as part of both the 2010 U.S. Department of Energy (DOE) sponsored Carbonaceous Aerosols and Radiative Effects Study (CARES), which took place in and around Sacramento, CA, and the 2012 Clean Air for London (ClearfLo) study. We focus on measurements that were made of aerosol particle optical properties, namely the wavelength-dependent light absorption, scattering and extinction. Interpretation of these optical property measurements is facilitated through consideration of complementary measurements of the aerosol particle chemical composition and size distributions. With these measurements, we addressed the following general scientific questions: 1. How does light scattering and extinction by atmospheric aerosol particles depend on particle composition, water uptake, and size? 2. To what extent is light absorption by aerosol particles enhanced through the mixing of black carbon with other particulate components? 3. What relationships exist between intensive aerosol particle optical properties, and how do these depend on particle source and photochemical aging? 4. How well do spectral deconvolution methods, which are commonly used in remote sensing, retrieve information about particle size distributions?

  6. Optical Properties and Immunoassay Applications of Noble Metal Nanoparticles

    Directory of Open Access Journals (Sweden)

    Shaoli Zhu

    2010-01-01

    Full Text Available Noble metal, especially gold (Au and silver (Ag nanoparticles exhibit unique and tunable optical properties on account of their surface plasmon resonance (SPR. In this paper, we mainly discussed the theory background of the enhanced optical properties of noble metal nanoparticles. Mie theory, transfer matrix method, discrete dipole approximation (DDA method, and finite-difference time domain (FDTD method applied brute-force computational methods for different nanoparticles optical properties. Some important nanostructure fabrication technologies such as nanosphere lithography (NSL and focused ion beam (FIB are also introduced in this paper. Moreover, these fabricated nanostructures are used in the plasmonic sensing fields. The binding signal between the antibody and antigen, amyloid-derived diffusible ligands (ADDLs-potential Alzheimer's disease (AD biomarkers, and staphylococcal enterotixn B (SEB in nano-Moore per liter (nM concentration level are detected by our designed nanobiosensor. They have many potential applications in the biosensor, environment protection, food security, and medicine safety for health, and so forth, fields.

  7. Computational studies of third-order nonlinear optical properties of ...

    Indian Academy of Sciences (India)

    Anuj Kumar

    2017-06-20

    Jun 20, 2017 ... Department of Physics, Jaypee University of Engineering and Technology, Raghogarh,. Guna 473 226, India. ∗ ... properties and other molecular properties of the organic nonlinear optical crystal 2-aminopyridinium p- toluenesulphonate ... nal processing, optical limiting, optical logic gates, laser radiation ...

  8. Enhancing Optical Communications with Brand New Fibers

    DEFF Research Database (Denmark)

    Morioka, Toshio; Awaji, Yoshinari; Ryf, Roland

    2012-01-01

    Optical fibers have often been considered to offer effectively infinite capacity to support the rapid traffic growth essential to our information society. However, as demand has grown and technology has developed, we have begun to realize that there is a fundamental limit to fiber capacity of ~ 100...... Tb/s per fiber for systems based on conventional single-core single-mode optical fiber as the transmission medium. This limit arises from the interplay of a number of factors including the Shannon limit, optical fiber nonlinearities, the fiber fuse effect, as well as optical amplifier bandwidth...... new fibers for space-division multiplexing and mode-division multiplexing....

  9. Optical properties of titanium dioxide nanotube arrays

    Energy Technology Data Exchange (ETDEWEB)

    Abdelmoula, Mohamed [Department of Physics, Northeastern University, Boston, Massachusetts 02115 (United States); Department of Materials Science, Carnegie Mellon University, Pittsburgh, PA 15213 (United States); Sokoloff, Jeffrey; Lu, Wen-Tao; Menon, Latika [Department of Physics, Northeastern University, Boston, Massachusetts 02115 (United States); Close, Thomas; Richter, Christiaan, E-mail: christiaan.richter@rit.edu [Department of Chemical Engineering, Rochester Institute of Technology, Rochester, New York, 14623 (United States)

    2014-01-07

    We present experimental measurements and a theoretical analysis of the near UV to NIR optical properties of free standing titania nanotube arrays. An improved understanding of the optical physics of this type of nanostructure is important to several next generation solar energy conversion technologies. We measured the transmission, reflection, and absorption of the electromagnetic spectrum from 300 nm to 1000 nm (UV to NIR) of titania nanotube arrays. We measured the total, specular, and diffuse reflection and transmission using both single point detection and an integrating sphere spectrometer. We find that the transmission, but not the reflection, of light (UV to NIR) through the nanotube array is well-explained by classic geometric optics using an effective medium model taking into account the conical geometry of the nanotubes. For wavelengths shorter than ∼500 nm, we find the surprising result that the reflection coefficient for light incident on the open side of the nanotube array is greater than the reflection coefficient for light incident on the closed “floor” of the nanotube array. We consider theoretical models based on the eikonal approximation, photonic crystal band theory, and a statistical treatment of scattering to explain the observed data. We attribute the fact that light with wavelengths shorter than 500 nm is more highly reflected from the open than the closed tube side as being due to disorder scattering inside the nanotube array.

  10. Thermo-optical Properties of Nanofluids

    International Nuclear Information System (INIS)

    Ortega, Maria Alejandra; Echevarria, Lorenzo; Rodriguez, Luis; Castillo, Jimmy; Fernandez, Alberto

    2008-01-01

    In this work, we report thermo-optical properties of nanofluids. Spherical gold nanoparticles obtained by laser ablation in condensed media were characterized using thermal lens spectroscopy in SDS-water solution pumping at 532 nm with a 10 ns pulsed laser-Nd-YAG system. Nanoparticles obtained by laser ablation were stabilized in the time by surfactants (Sodium Dodecyl-Sulfate or SDS) in different molar concentrations. The morphology and size of the gold nanoparticles were determined by transmission electron microscopy (TEM). The plasmonic resonance bands in gold nanoparticles are responsible of the light optical absorption of this wavelength. The position of the absorption maximum and width band in the UV-Visible spectra is given by the morphological characteristics of these systems. The thermo-optical constant such as thermal diffusion, thermal conductivity and dn/dT are functions of nanoparticles sizes and dielectric constant of the media. The theoretical model existents do not describe completely this relations because is not possible separate the contributions due to nanoparticles size, factor form and dielectric constant. The thermal lens signal obtained is also dependent of nanoparticles sizes. This methodology can be used in order to evaluate nanofluids and characterizing nanoparticles in different media. These results are expected to have an impact in bioimaging, biosensors and other technological applications such as cooler system

  11. Optical properties and sensing applications of stellated and bimetallic nanoparticles

    Science.gov (United States)

    Smith, Alison F.

    This dissertation focuses on developing guidelines to aid in the design of new bimetallic platforms for sensing applications. Stellated metal nanostructures are a class of plasmonic colloids in which large electric field enhancements can occur at sharp features, making them excellent candidates for surface enhanced Raman spectroscopy (SERS) and surface enhanced infrared spectroscopy (SE-IRS) platforms. Shape-dependent rules for convex polyhedra such as cubes or octahedra exist, which describe far-field scattering and near-field enhancements. However, such rules are lacking for their concave (stellated) counterparts. This dissertation presents the optical response of stellated Au nanocrystals with Oh, D4h, D3h, C2v, and T d symmetry, which were modeled to systematically investigate the role of symmetry, branching, and particle orientation with respect to excitation source using finite difference time domain (FDTD) calculations. Expanding on stellated nanostructures, bimetallic compositions introduce an interplay between overall architecture and composition to provide tunable optical properties and the potential of new functionality. However, decoupling the complex compositional and structural contributions to the localized surface plasmon resonance (LSPR) remains a challenge, especially when the monometallic counterparts are not synthetically accessible for comparison and the theoretical tools for capturing gradient compositions are lacking. This dissertation explores a stellated Au-Pd nanocrystal model system with Oh symmetry to decouple structural and complex compositional effects on LSPR. (Abstract shortened by ProQuest.).

  12. Optical properties of diamond like carbon nanocomposite thin films

    Science.gov (United States)

    Alam, Md Shahbaz; Mukherjee, Nillohit; Ahmed, Sk. Faruque

    2018-05-01

    The optical properties of silicon incorporated diamond like carbon (Si-DLC) nanocomposite thin films have been reported. The Si-DLC nanocomposite thin film deposited on glass and silicon substrate by radio frequency plasma enhanced chemical vapor deposition (RF-PECVD) process. Fourier transformed infrared spectroscopic analysis revealed the presence of different bonding within the deposited films and deconvolution of FTIR spectra gives the chemical composition i.e., sp3/sp2 ratio in the films. Optical band gap calculated from transmittance spectra increased from 0.98 to 2.21 eV with a variation of silicon concentration from 0 to 15.4 at. %. Due to change in electronic structure by Si incorporation, the Si-DLC film showed a broad photoluminescence (PL) peak centered at 467 nm, i.e., in the visible range and its intensity was found to increase monotonically with at. % of Si.

  13. Optical Properties of Airborne Soil Organic Particles

    Energy Technology Data Exchange (ETDEWEB)

    Veghte, Daniel P. [William; China, Swarup [William; Weis, Johannes [Chemical; Department; Kovarik, Libor [William; Gilles, Mary K. [Chemical; Laskin, Alexander [Department

    2017-09-27

    Recently, airborne soil organic particles (ASOP) were reported as a type of solid organic particles emitted after water droplets impacted wet soils. Chemical constituents of ASOP are macromolecules such as polysaccharides, tannins, and lignin (derived from degradation of plants and biological organisms). Optical properties of ASOP were inferred from the quantitative analysis of the electron energy-loss spectra acquired over individual particles in the transmission electron microscope. The optical constants of ASOP are further compared with those measured for laboratory generated particles composed of Suwanee River Fulvic Acid (SRFA) reference material, which was used as a laboratory surrogate of ASOP. The particle chemical compositions were analyzed using energy dispersive x-ray spectroscopy, electron energy-loss spectroscopy, and synchrotron-based scanning transmission x-ray microscopy with near edge x-ray absorption fine structure spectroscopy. ASOP and SRFA exhibit similar carbon composition, but SRFA has minor contributions of S and Na. When ASOP are heated to 350 °C their absorption increases as a result of their pyrolysis and partial volatilization of semi-volatile organic constituents. The retrieved refractive index (RI) at 532 nm of SRFA particles, ASOP, and heated ASOP were 1.22-62 0.07i, 1.29-0.07i, and 1.90-0.38i, respectively. Compared to RISRFA, RIASOP has a higher real part but similar imaginary part. These measurements of ASOP optical constants suggest that they have properties characteristic of atmospheric brown carbon and therefore their potential effects on the radiative forcing of climate need to be assessed in atmospheric models.

  14. Optical properties on thermally evaporated and heat-treated ...

    Indian Academy of Sciences (India)

    Administrator

    of the intra-molecular bonds between the powder compounds and thin films. The optical ... Keywords. Phthalocyanine; thin films; optical properties; absorption spectra. 1. .... Leica Cambridge scanning electron microscope (model. Stereoscan ...

  15. Structural, optical and electrical properties of chemically deposited ...

    Indian Academy of Sciences (India)

    Structural, optical and electrical properties of chemically deposited nonstoichiometric copper ... One of these compounds, CuInSe2, with its optical absorption .... is clear from SEM images that the number of grains goes on increasing with the ...

  16. Linear and nonlinear optical properties of borate crystals as ...

    Indian Academy of Sciences (India)

    Unknown

    crystal series, with an accuracy acceptable for materials development/design, and answer the questions often ... Optical property; nonlinear optical crystals; first principles calculation. 1. ..... system, and is not in concept suitable to excitation pro-.

  17. Effect of capping agents on optical and antibacterial properties of ...

    Indian Academy of Sciences (India)

    Administrator

    unique optical properties resulting from quantum con- finement ... them suitable in application such as biomedical label- ling,4 solar ... All optical measurements were carried out at ..... QDs with biomolecules and to use them as biosensors,.

  18. Enhancing the magnetic properties of magnetic nanoparticles

    DEFF Research Database (Denmark)

    Ahlburg, Jakob; Saura-Múzquiz, Matilde; Stingaciu, Marian

    with a similar magnetic performance. There are several different ways of enhancing magnetic properties of 3d magnetic compounds. This includes, size control, core-shell particles or mixing hard and soft magnetic materials together to achieve an exchange coupling between the compounds and enhancing the magnetic...... energy product. In order to control the particle size, a hydrothermal synthesis is preferred. This followed by reduction or the oxides into either core shell particles, or a mixture of magnetic oxides and a metallic phase....

  19. Dynamic optical bistability in resonantly enhanced Raman generation

    International Nuclear Information System (INIS)

    Novikova, I.; Phillips, D.F.; Zibrov, A.S.; Andre, A.; Walsworth, R.L.

    2004-01-01

    We report observations of novel dynamic behavior in resonantly enhanced stimulated Raman scattering in Rb vapor. In particular, we demonstrate a dynamic hysteresis of the Raman scattered optical field in response to changes of the drive laser field intensity and/or frequency. This effect may be described as a dynamic form of optical bistability resulting from the formation and decay of atomic coherence. We have applied this phenomenon to the realization of an all-optical switch

  20. Quasistatic limit for plasmon-enhanced optical chirality

    Science.gov (United States)

    Finazzi, Marco; Biagioni, Paolo; Celebrano, Michele; Duò, Lamberto

    2015-05-01

    We discuss the possibility of enhancing the chiroptical response from molecules uniformly distributed around nanostructures that sustain localized plasmon resonances. We demonstrate that the average optical chirality in the near field of any plasmonic nanostructure cannot be significantly higher than that in a plane wave. This conclusion stems from the quasistatic nature of the nanoparticle-enhanced electromagnetic fields and from the fact that, at optical frequencies, the magnetic response of matter is much weaker than the electric one.

  1. Optical properties of calcium barium niobate

    Energy Technology Data Exchange (ETDEWEB)

    Heine, Urs; Betzler, Klaus [Department of Physics, University of Osnabrueck (Germany); Burianek, Manfred; Muehlberg, Manfred [Institute of Crystallography, University of Cologne (Germany)

    2010-07-01

    We report on optical measurements on the novel tungsten bronze type calcium barium niobate. [001]-oriented transparent and colorless single crystals were grown by the Czochralski method with dimensions of 12 mm in diameter and about 80 mm in length. With its relatively high Curie temperature of about 538 K for the congruently melting composition of 28.1 mole% calcium and its high nonlinear coefficients, CBN is a promising material for future applications. Recent experiments revealed, that the application of an external electric field of several kV/cm to CBN at room temperature leads to an increasing opacity of the sample. This might be a drawback considering the future usability of CBN in optical systems. We present investigations on the transmittance behaviour of CBN under external electric fields, demonstrating the erasement of the clouding without affecting the polarization. Experiments have been performed at temperatures ranging from room temperature to approximately 480 K. When heating up the sample, its colorless appearance changes to a light yellow, which can be attributed to a shift of the band edge to longer wavelengths with increasing temperature. To further investigate the transmittance properties of CBN, measurements of the band edge under various temperatures up to the ferroelectric phase transition have been performed.

  2. Tellurium quantum dots: Preparation and optical properties

    Science.gov (United States)

    Lu, Chaoyu; Li, Xueming; Tang, Libin; Lai, Sin Ki; Rogée, Lukas; Teng, Kar Seng; Qian, Fuli; Zhou, Liangliang; Lau, Shu Ping

    2017-08-01

    Herein, we report an effective and simple method for producing Tellurium Quantum dots (TeQDs), zero-dimensional nanomaterials with great prospects for biomedical applications. Their preparation is based on the ultrasonic exfoliation of Te powder dispersed in 1-methyl-2-pyrrolidone. Sonication causes the van der Waals forces between the structural hexagons of Te to break so that the relatively coarse powder breaks down into nanoscale particles. The TeQDs have an average size of about 4 nm. UV-Vis absorption spectra of the TeQDs showed an absorption peak at 288 nm. Photoluminescence excitation (PLE) and photoluminescence (PL) are used to study the optical properties of TeQDs. Both the PLE and PL peaks revealed a linear relationship against the emission and excitation energies, respectively. TeQDs have important potential applications in biological imaging and catalysis as well as optoelectronics.

  3. Orientation-averaged optical properties of natural aerosol aggregates

    International Nuclear Information System (INIS)

    Zhang Xiaolin; Huang Yinbo; Rao Ruizhong

    2012-01-01

    Orientation-averaged optical properties of natural aerosol aggregates were analyzed by using discrete dipole approximation (DDA) for the effective radius in the range of 0.01 to 2 μm with the corresponding size parameter from 0.1 to 23 for the wavelength of 0.55 μm. Effects of the composition and morphology on the optical properties were also investigated. The composition show small influence on the extinction-efficiency factor in Mie scattering region, scattering- and backscattering-efficiency factors. The extinction-efficiency factor with the size parameter from 9 to 23 and asymmetry factor with the size parameter below 2.3 are almost independent of the natural aerosol composition. The extinction-, absorption, scattering-, and backscattering-efficiency factors with the size parameter below 0.7 are irrespective of the aggregate morphology. The intrinsic symmetry and discontinuity of the normal direction of the particle surface have obvious effects on the scattering properties for the size parameter above 4.6. Furthermore, the scattering phase functions of natural aerosol aggregates are enhanced at the backscattering direction (opposition effect) for large size parameters in the range of Mie scattering. (authors)

  4. Optical properties of melting first-year Arctic sea ice

    Science.gov (United States)

    Light, Bonnie; Perovich, Donald K.; Webster, Melinda A.; Polashenski, Christopher; Dadic, Ruzica

    2015-11-01

    The albedo and transmittance of melting, first-year Arctic sea ice were measured during two cruises of the Impacts of Climate on the Eco-Systems and Chemistry of the Arctic Pacific Environment (ICESCAPE) project during the summers of 2010 and 2011. Spectral measurements were made for both bare and ponded ice types at a total of 19 ice stations in the Chukchi and Beaufort Seas. These data, along with irradiance profiles taken within boreholes, laboratory measurements of the optical properties of core samples, ice physical property observations, and radiative transfer model simulations are employed to describe representative optical properties for melting first-year Arctic sea ice. Ponded ice was found to transmit roughly 4.4 times more total energy into the ocean, relative to nearby bare ice. The ubiquitous surface-scattering layer and drained layer present on bare, melting sea ice are responsible for its relatively high albedo and relatively low transmittance. Light transmittance through ponded ice depends on the physical thickness of the ice and the magnitude of the scattering coefficient in the ice interior. Bare ice reflects nearly three-quarters of the incident sunlight, enhancing its resiliency to absorption by solar insolation. In contrast, ponded ice absorbs or transmits to the ocean more than three-quarters of the incident sunlight. Characterization of the heat balance of a summertime ice cover is largely dictated by its pond coverage, and light transmittance through ponded ice shows strong contrast between first-year and multiyear Arctic ice covers.

  5. Sensitivity enhancement in evanescent optical waveguidesensors

    NARCIS (Netherlands)

    Veldhuis, G.J.; Parriaux, O.; Hoekstra, Hugo; Lambeck, Paul

    2000-01-01

    It is shown, that the sensitivity of the effective refractive index on the cladding index in evanescent optical waveguide sensors, can be larger than unity. This implies that the attenuation of a guided wave propagating in a waveguide immersed in an absorptive medium can be made larger than that of

  6. Surface enhanced Raman optical activity (SEROA)

    DEFF Research Database (Denmark)

    Abdali, Salim; Blanch, E.W.

    2008-01-01

    Raman optical activity (ROA) directly monitors the stereochemistry of chiral molecules and is now an incisive probe of biomolecular structure. ROA spectra contain a wealth of information on tertiary folding, secondary structure and even the orientation of individual residues in proteins and nucleic...

  7. Analysis of nonlinear optical properties in donor–acceptor materials

    Energy Technology Data Exchange (ETDEWEB)

    Day, Paul N. [Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio 45433 (United States); General Dynamics Information Technology, Inc., Dayton, Ohio 45431 (United States); Pachter, Ruth [Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio 45433 (United States); Nguyen, Kiet A. [Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio 45433 (United States); UES, Inc., Dayton, Ohio 45432 (United States)

    2014-05-14

    Time-dependent density functional theory has been used to calculate nonlinear optical (NLO) properties, including the first and second hyperpolarizabilities as well as the two-photon absorption cross-section, for the donor-acceptor molecules p-nitroaniline and dimethylamino nitrostilbene, and for respective materials attached to a gold dimer. The CAMB3LYP, B3LYP, PBE0, and PBE exchange-correlation functionals all had fair but variable performance when compared to higher-level theory and to experiment. The CAMB3LYP functional had the best performance on these compounds of the functionals tested. However, our comprehensive analysis has shown that quantitative prediction of hyperpolarizabilities is still a challenge, hampered by inadequate functionals, basis sets, and solvation models, requiring further experimental characterization. Attachment of the Au{sub 2}S group to molecules already known for their relatively large NLO properties was found to further enhance the response. While our calculations show a modest enhancement for the first hyperpolarizability, the enhancement of the second hyperpolarizability is predicted to be more than an order of magnitude.

  8. Optical characterization of OLED emitter properties by radiation pattern analyses

    Energy Technology Data Exchange (ETDEWEB)

    Flaemmich, Michael

    2011-09-08

    Researches in both, academia and industry are investigating optical loss channels in OLED layered systems by means of optical simulation tools in order to derive promising concepts for a further enhancement of the overall device performance. Besides other factors, the prospects of success of such optimization strategies rely severely on the credibility of the optical input data. The present thesis provides a guideline to measure the active optical properties of OLED emitter materials in situ by radiation pattern analyses. Reliable and widely applicable methods are introduced to determine the internal electroluminescence spectrum, the profile of the emission zone, the dipole emitter orientation, and the internal luminescence quantum efficiency of emissive materials from the optical far field emission of OLEDs in electrical operation. The proposed characterization procedures are applied to sets of OLEDs containing both, fluorescent polymeric materials as well as phosphorescent small-molecular emitters, respectively. On the one hand, quite expected results are obtained. On the other hand, several novel and truly surprising results are found. Most importantly, this thesis contains the first report of a non-isotropic, mainly parallel emitter orientation in a phosphorescent small-molecular guest-host system (Ir(MDQ)2(acac) in a-NPD). Due to the latter result, emitter orientation based optimization of phosphorescent OLEDs seems to be within reach. Since parallel dipoles emit preferably into air, the utilization of smart emissive materials with advantageous molecular orientation is capable to boost the efficiency of phosphorescent OLEDs by 50%. Materials design, the influence of the matrix material and the substrate, as well as film deposition conditions are just a few parameters that need to be studied further in order to exploit the huge potential of the dipole emitter orientation in phosphorescent OLEDs.

  9. Enhancement of porous silicon photoluminescence property by lithium chloride treatment

    Science.gov (United States)

    Azaiez, Khawla; Zaghouani, Rabia Benabderrahmane; Khamlich, Saleh; Meddeb, Hosny; Dimassi, Wissem

    2018-05-01

    Porous silicon (PS) decorated by several nanostructured metal elements has still aroused interests as promising composites in many industrial applications. With the focus mainly on the synthesis, the aspect of stability against optical irradiation of such materials has so far not been thoroughly addressed. This work focuses primarily on the influence of lithium chloride solution (LiCl) treatment on the physical properties of PS. Variations in the structural and optoelectronic properties of PS were observed after immersion in (LiCl), as revealed by the obtained analyses. Moreover, enhanced photoluminescence (PL) property of the PS after passivation by lithium particles was clearly shown, and their presence on the surface of the microporous silicon was confirmed by FTIR spectroscopy and atomic force microscopy. An improvement of the minority carrier lifetime was also obtained, which was attributed to the decrease of the surface recombination velocity after LiCl treatment.

  10. Controlling steady-state and dynamical properties of atomic optical bistability

    CERN Document Server

    Joshi, Amitabh

    2012-01-01

    This book provides a comprehensive introduction to the theoretical and experimental studies of atomic optical bistability and multistability, and their dynamical properties in systems with two- and three-level inhomogeneously-broadened atoms inside an optical cavity. By making use of the modified linear absorption and dispersion, as well as the greatly enhanced nonlinearity in the three-level electromagnetically induced transparency system, the optical bistablity and efficient all-optical switching can be achieved at relatively low laser powers, which can be well controlled and manipulated. Un

  11. Optical properties and photoluminescence of tetrahexyl-sexithiophene allotropes

    NARCIS (Netherlands)

    Botta, C; Destri, S; Porzio, W; Bongiovanni, G; Loi, MA; Mura, A; Tubino, R

    2001-01-01

    The optical absorption, Raman scattering and photoluminescence of two phases of tetrahexyl-sexithiophene (4HT6) display properties coherently related to the different molecular conformations imposed by the chain packing. We analyse the temperature dependence of the optical properties of a sample in

  12. Optical properties of metallic multi-layer films

    International Nuclear Information System (INIS)

    Dimmich, R.

    1991-09-01

    Optical properties of multi-layer films consisting of alternating layers of two different metals are studied on the basis of the Maxwell equations and the Boltzmann transport theory. The influence of free-electron scattering at the film external surface and at the interfaces is taken into account and considered as a function of the electromagnetic field frequency and the structure modulation wavelength. Derived formulas for optical coefficients are valid at low frequencies, where the skin effect is nearly classical, as well as in the near-infrared, visible and ultraviolet spectral ranges, where the skin effect has the anomalous nature. It is shown that the obtained results are apparently dependent on the values of the scattering parameters. What is more, the oscillatory nature of analyzed spectra is observed, where the two oscillation periods may appear on certain conditions. The oscillations result from the electron surface and interface scattering and their amplitudes and periods depend on the boundary conditions for free-electron scattering. Finally, the application of the interference phenomenon in dielectric layers is proposed to obtain the enhancement of the non distinct details which can appear in optical spectra of metallic films. (author). 31 refs, 6 figs

  13. Optical and transport properties of polyaniline films

    International Nuclear Information System (INIS)

    Tzamalis, Georgios

    2002-01-01

    This thesis presents the results of a comprehensive study on the transport and optical properties of polyaniline (PANI) films. The films are derived by protonation (doping) of the emeraldine base form of polyaniline, as synthesized in Durham, with either 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPSA) or 10-camphorsulfonic acid. Thus, two distinct PANI systems are obtained: PANI-CSA and PANI-AMPSA. The variation of the doping level can affect the metallic properties of the final system, so that samples close to the boundary as well as samples at either side of a disorder induced metal-insulator can be obtained. The relation between the doping level and the degree of disorder, along with the existence of an inherently metallic behaviour in PANI, are investigated through a series of experiments. Temperature dependent dc conductivity measurements ranging from 10-295 K are performed using a closed loop helium cryostat under dynamic vacuum (∼10 -5 mbar). From the conductivity data curves, typical fingerprints of the metallic behaviour are detected for certain samples and an initial estimate of the degree of disorder is implicitly attained. More specific information regarding the microscopic contributions to the transport mechanisms is obtained via low temperature (down to 1.5 K) magnetoconductance measurements on selected samples. The magnetic field dependence of conductivity for fields up to 14 T is measured and the suitability of the localization-interaction model for the understanding of the transport mechanism in PANI is examined. Infrared reflectivity (20-9000 cm -1 ) measurements on samples of both PANI systems are performed. The experimental configuration permits the determination of the sample's absolute reflectivity. The optical constants are deduced from Kramers-Kronig analysis of the reflectivity data. Typical features of metallic behaviour are examined and analysed in the context of the localization modified Drude model. The results are shown to be

  14. OPTICAL PROPERTIES OF CARBAMIDE AQUEOUS SOLUTIONS

    Directory of Open Access Journals (Sweden)

    E. V. Avramenko

    2016-03-01

    Full Text Available Subject of Research. The paper presents the results of measurements of refractometric properties (refractive index n, its temperature factor dn/dt and the ultraviolet spectral absorption in carbonic acid diamide aqueous solutions (carbamide depending on solid residue mass fraction md = 0-50 % and on temperaturet = 10-70 °C.Method of Research. Laboratory methods ofliquid-phase medium refractometry and ultraviolet spectrophotometry were applied for the research. We carried out computational modeling of electronic states spectrum for the carbonic acid diamide molecule and theoretical calculation of the fundamental electronic absorption of the molecule in the ultraviolet wavelenght region.Main Results. We have established that the solution concentration md has a nonlinear character and may be represented by the quadratic polynomial with the error Δn= ± 0,0005. We have shown the refractive indexdependence on temperature n(t changes in linear fashion att = 10-70 °C.At that, the inclination of lines n(t increases at the increase of md; so, the temperature factor dn/dt may be approximated by the quadratic polynomial. Transmission spectra of solutions in the spectral region λ= 225-760 nm have no special features except for the sharp edge in the short-wavelength region; the fundamental electronic absorptionis responsible for it. We have established that dispersion dependences of the refraction index n(λ;md in aqueous solutions of carbamide at λ= 360-760 nm and at md = 0-50 % may be calculated with the satisfactory error without additional adjustable parameters from the ultraviolet absorption data in terms of the one-dimentional oscillator Lorentz model.PracticalRelevance. Representedmeasurements of carbonic acid diamide aqueous solutions optical properties may be applied for the adjustment and calibration of commercial refractometers at processing lines of the AdBlue reagent manufacture for the selective catalytic reduction (SCR of motor transport

  15. Comparing optical properties of different species of diatoms

    DEFF Research Database (Denmark)

    Maibohm, Christian; Friis, Søren Michael Mørk; Su, Y.

    2015-01-01

    species dependent with huge variety in size, shape, and micro- structure. We have experimentally investigated optical properties of frustules of several species of diatoms to further understand light harvesting properties together with commo n traits, effects and differences between the different...... analysis software. The software uses parameters which are extracted from experimental im ages as basis for simulation and allows us to extract the influence of the different elements of the frustule. The information could be used both for predicting optical properties of diatoms and by changing frustule...... parameters, maybe by altering growth conditions of the diatoms tailor their optical properties....

  16. Shape induced (spherical, sheets and rods) optical and magnetic properties of CdS nanostructures with enhanced photocatalytic activity for photodegradation of methylene blue dye under ultra-violet irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Ahmed, Bilal; Kumar, Sachin; Kumar, Sumeet; Ojha, Animesh K., E-mail: animesh@mnnit.ac.in

    2016-09-15

    CdS nanostructures of different shapes such as, nanoparticles (NPs), nanosheets (NS) and nanorods (NRs) have been synthesized by one step chemical solvothermal method. The synthesized samples were characterized by X-ray diffractometer (XRD), transmission electron microscopy (TEM), photoluminescence (PL) spectroscopy, UV–visible (UV-VIS) spectroscopy, Raman spectroscopy (RS) and vibrating sample magnetometer (VSM) techniques. The effect of shape on optical and magnetic properties of CdS nanostructures was studied. The optical band gap and emission spectra are found to be shape dependent. CdS NRs were found to have high saturation (Ms) magnetization than that of CdS NPs and NS. The role of shape on photocatalytic performance of CdS NPs, NS and NRs was investigated by monitoring the photodegradation of methylene blue (MB) dye under the UV irradiation of wavelength 365 nm. The lower recombination rate of electron-hole pairs and larger surface area as reactive facets for adsorption of MB dye molecules in CdS NS are mainly lead to the better photocatalytic performance of CdS NS compared to NPs and NRs. - Highlights: • Synthesis of CdS nanostructures with different shapes (spherical, rod and sheet) by easy and low cost solvothermal method. • Shape induced optical and magnetic properties of CdS nanostructures have been investigated. • The shapes of nanostructures play an important role for photocatalytic performance of CdS nanostructures.

  17. Optical properties of marine waters and the development of bio-optical algorithms

    Digital Repository Service at National Institute of Oceanography (India)

    Desa, E.

    This paper presents the primary optical variables used in the measurement of the optical properties of marine waters. How can in-situ measurements be used in the optical recognition of coastal and open ocean waters. We then look at bio...

  18. Enhanced linear photonic nanojet generated by core-shell optical microfibers

    Science.gov (United States)

    Liu, Cheng-Yang; Yen, Tzu-Ping; Chen, Chien-Wen

    2017-05-01

    The generation of linear photonic nanojet using core-shell optical microfiber is demonstrated numerically and experimentally in the visible light region. The power flow patterns for the core-shell optical microfiber are calculated by using the finite-difference time-domain method. The focusing properties of linear photonic nanojet are evaluated in terms of length and width along propagation and transversal directions. In experiment, the silica optical fiber is etched chemically down to 6 μm diameter and coated with metallic thin film by using glancing angle deposition. We show that the linear photonic nanojet is enhanced clearly by metallic shell due to surface plasmon polaritons. The large-area superresolution imaging can be performed by using a core-shell optical microfiber in the far-field system. The potential applications of this core-shell optical microfiber include micro-fluidics and nano-structure measurements.

  19. Anisotropic nanomaterials: Synthesis, optical and magnetic properties, and applications

    Science.gov (United States)

    Banholzer, Matthew John

    As nanoscience and nanotechnology mature, anisotropic metal nanostructures are emerging in a variety of contexts as valuable class of nanostructures due to their distinctive attributes. With unique properties ranging from optical to magnetic and beyond, these structures are useful in many new applications. Chapter two discusses the nanodisk code: a linear array of metal disk pairs that serve as surface-enhanced Raman scattering substrates. These multiplexing structures employ a binary encoding scheme, perform better than previous nanowires designs (in the context of SERS) and are useful for both convert encoding and tagging of substrates (based both on spatial disk position and spectroscopic response) as well as biomolecule detection (e.g. DNA). Chapter three describes the development of improved, silver-based nanodisk code structures. Work was undertaken to generate structures with high yield and reproducibility and to reoptimize the geometry of each disk pair for maximum Raman enhancement. The improved silver structures exhibit greater enhancement than Au structures (leading to lower DNA detection limits), convey additional flexibility, and enable trinary encoding schemes where far more unique structures can be created. Chapter four considers the effect of roughness on the plasmonic properties of nanorod structures and introduces a novel method to smooth the end-surfaces of nanorods structures. The smoothing technique is based upon a two-step process relying upon diffusion control during nanowires growth and selective oxidation after each step of synthesis is complete. Empirical and theoretical work show that smoothed nanostructures have superior and controllable optical properties. Chapter five concerns silica-encapsulated gold nanoprisms. This encapsulation allows these highly sensitive prisms to remain stable and protected in solution, enabling their use as class-leading sensors. Theoretical study complements the empirical work, exploring the effect of

  20. Optical wireless links with enhanced linearity and selectivity [Invited

    Science.gov (United States)

    Green, Roger J.; Sweet, C.; Idrus, S.

    2005-10-01

    Optical wireless is an attractive medium as an alternative to optical fiber communications, and also to RF, because of its high bandwidth and relative ease of use, especially when it comes to deployment in new physical situations. We describe an optical wireless link approach that offers a performance that gives analog transmission with significantly reduced distortion levels and enhanced reception sensitivity by combining a novel hybrid detector-amplifier technique. Reduction of distortion by 40 dB and improvement in sensitivity of 20-30 dB is possible, using the techniques described.

  1. Enhanced optical limiting effect in fluorine-functionalized graphene oxide

    Science.gov (United States)

    Zhang, Fang; Wang, Zhengping; Wang, Duanliang; Wang, Shenglai; Xu, Xinguang

    2017-09-01

    Nonlinear optical absorption of fluorine-functionalized graphene oxide (F-GO) solution was researched by the open-aperture Z-scan method using 1064 and 532 nm lasers as the excitation sources. The F-GO dispersion exhibited strong optical limiting property and the fitted results demonstrated that the optical limiting behavior was the result of a two-photon absorption process. For F-GO nanosheets, the two-photon absorption coefficients at 1064 nm excitation are 20% larger than the values at 532 nm excitation and four times larger than that of pure GO nanosheets. It indicates that the doping of fluorine can effectively improve the nonlinear optical property of GO especially in infrared waveband, and fluorine-functionalized graphene oxide is an excellent nonlinear absorption material in infrared waveband.

  2. Complementary bowtie aperture for localizing and enhancing optical magnetic field

    Science.gov (United States)

    Zhou, Nan; Kinzel, Edward C.; Xu, Xianfan

    2011-08-01

    Nanoscale bowtie antenna and bowtie aperture antenna have been shown to generate strongly enhanced and localized electric fields below the diffraction limit in the optical frequency range. According to Babinet's principle, their complements will be efficient for concentrating and enhancing magnetic fields. In this Letter, we discuss the enhancement of magnetic field intensity of nanoscale complementary bowtie aperture as well as complementary bowtie aperture antenna, or diabolo nanoantenna. We show that the complementary bowtie antenna resonates at a smaller wavelength and thus is more suitable for applications near visible wavelengths. The near-field magnetic intensity can be further enhanced by the addition of groove structures that scatter surface plasmon.

  3. Optical properties of armchair (7, 7) single walled carbon nanotubes

    International Nuclear Information System (INIS)

    Gharbavi, K.; Badehian, H.

    2015-01-01

    Full potential linearized augmented plane waves method with the generalized gradient approximation for the exchange-correlation potential was applied to calculate the optical properties of (7, 7) single walled carbon nanotubes. The both x and z directions of the incident photons were applied to estimate optical gaps, dielectric function, electron energy loss spectroscopies, optical conductivity, optical extinction, optical refractive index and optical absorption coefficient. The results predict that dielectric function, ε (ω), is anisotropic since it has higher peaks along z-direction than x-direction. The static optical refractive constant were calculated about 1.4 (z-direction) and 1.1 (x- direction). Moreover, the electron energy loss spectroscopy showed a sharp π electron plasmon peaks at about 6 eV and 5 eV for z and x-directions respectively. The calculated reflection spectra show that directions perpendicular to the tube axis have further optical reflection. Moreover, z-direction indicates higher peaks at absorption spectra in low range energies. Totally, increasing the diameter of armchair carbon nanotubes cause the optical band gap, static optical refractive constant and optical reflectivity to decrease. On the other hand, increasing the diameter cause the optical absorption and the optical conductivity to increase. Moreover, the sharp peaks being illustrated at optical spectrum are related to the 1D structure of CNTs which confirm the accuracy of the calculations

  4. Different optical properties in different periodic slot cavity geometrical morphologies

    Science.gov (United States)

    Zhou, Jing; Shen, Meng; Du, Lan; Deng, Caisong; Ni, Haibin; Wang, Ming

    2016-09-01

    In this paper, optical properties of two-dimensional periodic annular slot cavity arrays in hexagonal close-packing on a silica substrate are theoretically characterized by finite difference time domain (FDTD) simulation method. By simulating reflectance spectra, electric field distribution, and charge distribution, we confirm that multiple cylindrical surface plasmon resonances can be excited in annular inclined slot cavities by linearly polarized light, in which the four reflectance dips are attributed to Fabry-Perot cavity resonances in the coaxial cavity. A coaxial waveguide mode TE11 will exist in these annular cavities, and the wavelengths of these reflectance dips are effectively tailored by changing the geometrical pattern of slot cavity and the dielectric materials filled in the cavities. These resonant wavelengths are localized in annular cavities with large electric field enhancement and dissipate gradually due to metal loss. The formation of an absorption peak can be explained from the aspect of phase matching conditions. We observed that the proposed structure can be tuned over the broad spectral range of 600-4000 nm by changing the outer and inner radii of the annular gaps, gap surface topography. Meanwhile, different lengths of the cavity may cause the shift of resonance dips. Also, we study the field enhancement at different vertical locations of the slit. In addition, dielectric materials filling in the annular gaps will result in a shift of the resonance wavelengths, which make the annular cavities good candidates for refractive index sensors. The refractive index sensitivity of annular cavities can also be tuned by the geometry size and the media around the cavity. Annular cavities with novel applications can be implied as surface enhanced Raman spectra substrates, refractive index sensors, nano-lasers, and optical trappers. Project supported by the National Natural Science Foundation of China (Grant No. 61178044), the Natural Science Foundation

  5. Novel optical properties of CdS:Zn rocksalt system (a theoretical study)

    Science.gov (United States)

    Khan, M. Junaid Iqbal; Nauman Usmani, M.; Kanwal, Zarfishan

    2017-11-01

    In present computational study, we focus on optical properties of Zn doped CdS for 1  ×  1  ×  2 and 2  ×  2  ×  2 supercell configurations. Cd atoms are substituted with Zn atoms and results for optical properties demonstrate different trends due to interaction of Zn with S atoms. The study has been performed by PBE-GGA approach using Wien2K within framework of DFT. TDOS and PDOS represent that S-3p states are responsible for conduction. For large supercell configuration, a tremendous change in optical properties has been observed due to different bonding. Optical absorption tends to increase in visible range which supports candidacy of Zn doped CdS for enhanced optoelectronic and nanotechnology applications.

  6. Optical Properties of Nanoparticle Systems Mie and Beyond

    CERN Document Server

    Quinten, Michael

    2011-01-01

    Unlike other books who concentrate on metallic nanoparticles with sizes less than 100 nm, the author discusses optical properties of particles with (a) larger size and (b) of any material. The intention of this book is to fill the gap in the description of the optical properties of small particles with sizes less than 1000 nm and to provide a comprehensive overview on the spectral behavior of nanoparticulate matter. The author concentrates on the linear optical properties elastic light scattering and absorption of single nanoparticles and on reflectance and transmittance of nanoparticle matter

  7. Optical properties of photoreceptor and retinal pigment epithelium cells investigated with adaptive optics optical coherence tomography

    Science.gov (United States)

    Liu, Zhuolin

    Human vision starts when photoreceptors collect and respond to light. Photoreceptors do not function in isolation though, but share close interdependence with neighboring photoreceptors and underlying retinal pigment epithelium (RPE) cells. These cellular interactions are essential for normal function of the photoreceptor-RPE complex, but methods to assess these in the living human eye are limited. One approach that has gained increased promise is high-resolution retinal imaging that has undergone tremendous technological advances over the last two decades to probe the living retina at the cellular level. Pivotal in these advances has been adaptive optics (AO) and optical coherence tomography (OCT) that together allow unprecedented spatial resolution of retinal structures in all three dimensions. Using these high-resolution systems, cone photoreceptor are now routinely imaged in healthy and diseased retina enabling fundamental structural properties of cones to be studied such as cell spacing, packing arrangement, and alignment. Other important cell properties, however, have remained elusive to investigation as even better imaging performance is required and thus has resulted in an incomplete understanding of how cells in the photoreceptor-RPE complex interact with light. To address this technical bottleneck, we expanded the imaging capability of AO-OCT to detect and quantify more accurately and completely the optical properties of cone photoreceptor and RPE cells at the cellular level in the living human retina. The first objective of this thesis was development of a new AO-OCT method that is more precise and sensitive, thus enabling a more detailed view of the 3D optical signature of the photoreceptor-RPE complex than was previously possible (Chapter 2). Using this new system, the second objective was quantifying the waveguide properties of individual cone photoreceptor inner and outer segments across the macula (Chapter 3). The third objective extended the AO

  8. Enhancing the magnetic properties of magnetic nanoparticles

    DEFF Research Database (Denmark)

    Ahlburg, Jakob; Saura-Múzquiz, Matilde; Stingaciu, Marian

    with a similar magnetic performance. There are several different ways of enhancing magnetic properties of 3d magnetic compounds. This includes, size control, core-shell particles or mixing hard and soft magnetic materials together to achieve an exchange coupling between the compounds and enhancing the magnetic...... energy product. In order to control the particle size, a hydrothermal synthesis is preferred. This followed by reduction or the oxides into either core shell particles, or a mixture of magnetic oxides and a metallic phase.......Strong magnets with a high energy product are vital when optimizing the efficiency in the electric industry. But since the rare earth metals, normally used for making strong permanent magnets, are both expensive and difficult to mine, a great demand has come to cheaper types of magnets...

  9. Optical properties of the human round window membrane

    Science.gov (United States)

    Höhl, Martin; DeTemple, Daphne; Lyutenski, Stefan; Leuteritz, Georg; Varkentin, Arthur; Schmitt, Heike Andrea; Lenarz, Thomas; Roth, Bernhard; Meinhardt-Wollweber, Merve; Morgner, Uwe

    2017-10-01

    Optical techniques are effective tools for diagnostic applications in medicine and are particularly attractive for the noninvasive analysis of biological tissues and fluids in vivo. Noninvasive examinations of substances via a fiber optic probe need to consider the optical properties of biological tissues obstructing the optical path. This applies to the analysis of the human perilymph, which is located behind the round window membrane. The composition of this inner ear liquid is directly correlated to inner ear hearing loss. In this work, experimental methods for studying the optical properties of the human round window membrane ex vivo are presented. For the first time, a comprehensive investigation of this tissue is performed, including optical transmission, forward scattering, and Raman scattering. The results obtained suggest the application of visible wavelengths (>400 nm) for investigating the perilymph behind the round window membrane in future.

  10. Nanocrystalline permanent magnets with enhanced properties

    International Nuclear Information System (INIS)

    Leonowicz, M.

    2002-01-01

    Parameters of permanent magnets result from the combination of intrinsic properties such as saturation magnetization, magnetic exchange, and magnetocrystalline energy, as well as microstructural parameters such as phase structure, grain size, and orientation. Reduction of grain size into nanocrystalline regime (∼ 50 nm) leads to the enhanced remanence which derives from ferromagnetic exchange coupling between highly refined grains. In this study the fundamental phenomena, quantities, and structure parameters, which define nanophase permanent magnets are presented and discussed. The theoretical considerations are confronted with experimental data for nanocrystalline Sm-Fe-N type permanent magnets. (author)

  11. Anomalous optical and electronic properties of dense sodium

    International Nuclear Information System (INIS)

    Li Dafang; Liu Hanyu; Wang Baotian; Shi Hongliang; Zhu Shaoping; Yan Jun; Zhang Ping

    2010-01-01

    Based on the density functional theory, we systematically study the optical and electronic properties of the insulating dense sodium phase (Na-hp4) reported recently (Ma et al., 2009). The structure is found optically anisotropic. Through Bader analysis, we conclude that ionicity exists in the structure and becomes stronger with increasing pressure.

  12. Application of Tietz potential to study optical properties of spherical ...

    Indian Academy of Sciences (India)

    c Indian Academy of Sciences. Vol. 85, No. 4. — journal of. October 2015 ... The physical properties of semiconductors such as optical, electronic, and thermodynamic .... can be used to reproduce the interaction potential energy curve of the A1.

  13. Spectroscopic properties of rare earths in optical materials

    CERN Document Server

    Parisi, Jürgen; Osgood, R; Warlimont, Hans; Liu, Guokui; Jacquier, Bernard

    2005-01-01

    Aimed at researchers and graduate students, this book provides up-to-date information for understanding electronic interactions that impact the optical properties of rare earth ions in solids. Its goal is to establish a connection between fundamental principles and the materials properties of rare-earth activated luminescent and laser optical materials. The theoretical survey and introduction to spectroscopic properties include electronic energy level structure, intensities of optical transitions, ion-phonon interactions, line broadening, and energy transfer and up-conversion. An important aspect of the book lies in its deep and detailed discussions on materials properties and the potential of new applications such as optical storage, information processing, nanophotonics, and molecular probes that have been identified in recent experimental studies. This volume will be a valuable reference book on advanced topics of rare earth spectroscopy and materials science.

  14. OPTICAL AND DYNAMIC PROPERTIES OF UNDOPED AND DOPED SEMICONDUCTOR NANOSTRUCTURES

    Energy Technology Data Exchange (ETDEWEB)

    Grant, C D; Zhang, J Z

    2007-09-28

    This chapter provides an overview of some recent research activities on the study of optical and dynamic properties of semiconductor nanomaterials. The emphasis is on unique aspects of these properties in nanostructures as compared to bulk materials. Linear, including absorption and luminescence, and nonlinear optical as well as dynamic properties of semiconductor nanoparticles are discussed with focus on their dependence on particle size, shape, and surface characteristics. Both doped and undoped semiconductor nanomaterials are highlighted and contrasted to illustrate the use of doping to effectively alter and probe nanomaterial properties. Some emerging applications of optical nanomaterials are discussed towards the end of the chapter, including solar energy conversion, optical sensing of chemicals and biochemicals, solid state lighting, photocatalysis, and photoelectrochemistry.

  15. Measurement of inherent optical properties in the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Suresh, T.; Desa, E.; Kurian, J.; Mascarenhas, A.A.M.Q.

    Inherent optical properties, absorption and began attenuation were measured in situ using a reflective tube absorption meter at nint wavelength, 412, 440, 488, 510, 555, 630, 650, 676 and 715 nm, in the Arabian Sea during March. Since inherent...

  16. Density functional study of : Electronic and optical properties

    Indian Academy of Sciences (India)

    K C Bhamu

    3Department of Physics, Swami Keshvanand Insitute of Technology, Management and Gramothan, ... Published online 20 June 2017. Abstract. This paper focusses on the electronic and optical properties of scandium-based silver delafossite.

  17. Optical properties of V-trough concentrators

    Energy Technology Data Exchange (ETDEWEB)

    Fraidenraich, N. [Universidade Federal de Pernambuco, Recife, PE Brasil (Brazil); Almeida, G. J.

    1991-07-01

    A new approach to study the optical behavior of V-trough concentrators is developed, based on the use of three characteristic angles defining the appearance, disappearance and return to the outside space of the cavity of a reflection mode. The probability of occurrence of a given number of reflections for beam radiation is determined as a function of these angles and the optical efficiency calculated. It is shown that the optical efficiency can be approximated by a function of two parameters, the angular acceptance function, T, and the mean number of reflections, n, as T * p{sup n/T}. Deviations between exact and approximate optical efficiency increase as n increases or as p decreases. For troughs with C ≤ 2.5 the maximal error for beam radiation is 3.4% for p ≥ 0.8 (8.3% for p ≥ 0.7). For diffuse radiation the maximal error is less than 2% for configurations whose optical efficiency is above 0.6. A further simplification was introduced to obtain the optical efficiency for diffuse radiation, approximating T by an analytical expression and n by an empirical linear function of the inverse of the vertex angle. Results accurate up to 5% for p = 0.8, were obtained. Increasing the concentration ratio, C, from 1.5 to 2.5 for a vertex angle being one third of the acceptance angle, decreased the optical efficiency from 0.74 to 0.59, for p = 0.8. For a given C, the dependence of the optical efficiency on the vertex angle is rather weak, suggesting that large trough angles might be favoured by cost-benefit analysis. (author)

  18. Noise and saturation properties of semiconductor quantum dot optical amplifiers

    DEFF Research Database (Denmark)

    Berg, Tommy Winther; Mørk, Jesper

    2002-01-01

    We present a detailed theoretical analysis of quantum dot optical amplifiers. Due to the presence of a reservoir of wetting layer states, the saturation and noise properties differ markedly from bulk or QW amplifiers and may be significantly improved.......We present a detailed theoretical analysis of quantum dot optical amplifiers. Due to the presence of a reservoir of wetting layer states, the saturation and noise properties differ markedly from bulk or QW amplifiers and may be significantly improved....

  19. Slow light enhanced optical nonlinearity in a silicon photonic crystal coupled-resonator optical waveguide.

    Science.gov (United States)

    Matsuda, Nobuyuki; Kato, Takumi; Harada, Ken-Ichi; Takesue, Hiroki; Kuramochi, Eiichi; Taniyama, Hideaki; Notomi, Masaya

    2011-10-10

    We demonstrate highly enhanced optical nonlinearity in a coupled-resonator optical waveguide (CROW) in a four-wave mixing experiment. Using a CROW consisting of 200 coupled resonators based on width-modulated photonic crystal nanocavities in a line defect, we obtained an effective nonlinear constant exceeding 10,000 /W/m, thanks to slow light propagation combined with a strong spatial confinement of light achieved by the wavelength-sized cavities.

  20. Electronic, Optical, and Thermal Properties of Reduced-Dimensional Semiconductors

    Science.gov (United States)

    Huang, Shouting

    Reduced-dimensional materials have attracted tremendous attention because of their new physics and exotic properties, which are of great interests for fundamental science. More importantly, the manipulation and engineering of matter on an atomic scale yield promising applications for many fields including nanoelectronics, nanobiotechnology, environments, and renewable energy. Because of the unusual quantum confinement and enhanced surface effect of reduced-dimensional materials, traditional empirical models suffer from necessary but unreliable parameters extracted from previously-studied bulk materials. In this sense, quantitative, parameter-free approaches are highly useful for understanding properties of reduced-dimensional materials and, furthermore, predicting their novel applications. The first-principles density functional theory (DFT) is proven to be a reliable and convenient tool. In particular, recent progress in many-body perturbation theory (MBPT) makes it possible to calculate excited-state properties, e.g., quasiparticle (QP) band gap and optical excitations, by the first-principles approach based on DFT. Therefore, during my PhD study, I employed first-principles calculations based on DFT and MBPT to systematically study fundamental properties of typical reduced-dimensional semiconductors, i.e., the electronic structure, phonons, and optical excitations of core-shell nanowires (NWs) and graphene-like two-dimensional (2D) structures of current interests. First, I present first-principles studies on how to engineer band alignments of nano-sized radial heterojunctions, Si/Ge core-shell NWs. Our calculation reveals that band offsets in these one-dimensional (1D) nanostructures can be tailored by applying axial strain or varying core-shell sizes. In particular, the valence band offset can be efficiently tuned across a wide range and even be diminished via applied strain. Two mechanisms contribute to this tuning of band offsets. Furthermore, varying the

  1. Effects of the oxygen fraction and substrate bias power on the electrical and optical properties of silicon oxide films by plasma enhanced chemical vapour deposition using TMOS/O2 gas

    International Nuclear Information System (INIS)

    Bang, S B; Chung, T H; Kim, Y; Kang, M S; Kim, J K

    2004-01-01

    Thin oxide films are deposited from tetramethoxysilane in an inductively coupled oxygen glow discharge supplied with radio frequency power. The chemical bonding states of deposited films are analysed by Fourier transform infrared spectroscopy. The deposition rate and optical properties are determined from spectroscopic ellipsometry. Capacitance-voltage measurements are performed in MOS capacitors to obtain the electrical properties of the deposited films. With these tools, the effects of the substrate bias power and the oxygen mole fraction in the gas on the properties of the film are investigated. The refractive index first decreases with an increase in the oxygen mole fraction, and then increases again, showing a behaviour opposite to that of the deposition rate. The deposition rate increases with increasing substrate bias power and then saturates, while the refractive index increases slightly with an increase in the substrate bias power. The fixed oxide charge density decreases with increasing oxygen fraction and with increasing substrate bias power, while the interface trap density increases with increasing oxygen fraction and with increasing substrate bias power

  2. Structural and optical properties of Si-doped Ag clusters

    KAUST Repository

    Mokkath, Junais Habeeb

    2014-03-06

    The structural and optical properties of AgN and Ag N-1Si1 (neutral, cationic, and anionic) clusters (N = 5 to 12) are systematically investigated using the density functional based tight binding method and time-dependent density functional theory, providing insight into recent experiments. The gap between the highest occupied and lowest unoccupied molecular orbitals and therefore the optical spectrum vary significantly under Si doping, which enables flexible tuning of the chemical and optical properties of Ag clusters. © 2014 American Chemical Society.

  3. Theoretical Studies of Optical Properties of Silver Nanoparticles

    International Nuclear Information System (INIS)

    Ye-Wan, Ma; Zhao-Wang, Wu; Li-Hua, Zhang; Jie, Zhang

    2010-01-01

    Optical properties of silver nanoparticles such as extinction, absorption and scattering efficiencies are studied based on Green's function theory. The numerical simulation results show that optical properties of silver nanoparticles are mainly dependent on their sizes and geometries; the localized plasmon resonance peak is red shifted when the dielectric constant of the particle's surrounding medium increases or when a substrate is presented. The influences of wave polarizations, the incident angles of light, the composite silver and multiply-layers on the plasmon resonance are also reported. The numerical simulation of optical spectra is a very useful tool for nanoparticle growth and characterization. (fundamental areas of phenomenology(including applications))

  4. Constitutive Modeling of the Mechanical Properties of Optical Fibers

    Science.gov (United States)

    Moeti, L.; Moghazy, S.; Veazie, D.; Cuddihy, E.

    1998-01-01

    Micromechanical modeling of the composite mechanical properties of optical fibers was conducted. Good agreement was obtained between the values of Young's modulus obtained by micromechanics modeling and those determined experimentally for a single mode optical fiber where the wave guide and the jacket are physically coupled. The modeling was also attempted on a polarization-maintaining optical fiber (PANDA) where the wave guide and the jacket are physically decoupled, and found not to applicable since the modeling required perfect bonding at the interface. The modeling utilized constituent physical properties such as the Young's modulus, Poisson's ratio, and shear modulus to establish bounds on the macroscopic behavior of the fiber.

  5. Structural and optical properties of Si-doped Ag clusters

    KAUST Repository

    Mokkath, Junais Habeeb; Schwingenschlö gl, Udo

    2014-01-01

    The structural and optical properties of AgN and Ag N-1Si1 (neutral, cationic, and anionic) clusters (N = 5 to 12) are systematically investigated using the density functional based tight binding method and time-dependent density functional theory, providing insight into recent experiments. The gap between the highest occupied and lowest unoccupied molecular orbitals and therefore the optical spectrum vary significantly under Si doping, which enables flexible tuning of the chemical and optical properties of Ag clusters. © 2014 American Chemical Society.

  6. The Electronic and Optical Properties of Au Doped Single-Layer Phosphorene

    Science.gov (United States)

    Zhu, Ziqing; Chen, Changpeng; Liu, Jiayi; Han, Lu

    2018-01-01

    The electronic properties and optical properties of single and double Au-doped phosphorene have been comparatively investigated using the first-principles plane-wave pseudopotential method based on density functional theory. The decrease from direct band gap 0.78 eV to indirect band gap 0.22 and 0.11 eV are observed in the single and double Au-doped phosphorene, respectively. The red shifts of absorbing edge occur in both doped systems, which consequently enhance the absorbing of infrared light in phosphorene. Band gap engineering can, therefore, be used to directly tune the optical absorption of phosphorene system by substitutional Au doping.

  7. Optical properties of nanowire metamaterials with gain

    DEFF Research Database (Denmark)

    Isidio de Lima, Joaquim Junior; Adam, Jost; Rego, Davi

    2016-01-01

    The transmittance, reflectance and absorption of a nanowire metamaterial with optical gain are numerically simulated and investigated. It is assumed that the metamaterial is represented by aligned silver nanowires embedded into a semiconductor matrix, made of either silicon or gallium phosphide....... The gain in the matrix is modeled by adding a negative imaginary part to the dielectric function of the semiconductor. It is found that the optical coefficients of the metamaterial depend on the gain magnitude in a non-trivial way: they can both increase and decrease with gain depending on the lattice...... constant of the metamaterial. This peculiar behavior is explained by the field redistribution between the lossy metal nanowires and the amplifying matrix material. These findings are significant for a proper design of nanowire metamaterials with low optical losses for diverse applications....

  8. Optical properties of Amorphous Semiconductors Part- II: Theory and analysis of optical properties

    International Nuclear Information System (INIS)

    Hogarth, C. A.

    1997-01-01

    The atomic and band structural properties of solids have been studied. Reflectance is concerned in spectroscopic measurement of transmission and absorption, since the incident light intensity must be corrected for the loss of light by reflection and which does not penetrate beyond the surface of the material studied.The procedure for estimating E opt and n from the absorption edge of an amorphous semiconductor has been discussed. In high refractive index glasses there is a general correlation between n and the density of the glasses and in designing a particular glass for an optical purpose this can provide a useful guide to composition. The Gladstone-Dale refractivity and the Newton-Drude refractivity have been calculated for different value of b and these relations have been tested for telluride semiconducting glasses and give reasonable agreement in estimations of n directly from the density ρ. 33 refs., 10 figs

  9. Efficient 3M PBS enhancing miniature projection optics

    Science.gov (United States)

    Yun, Zhisheng; Nevitt, Timothy; Willett, Stephen; Mortenson, Dave; Le, John; McDowell, Erin; Kent, Susan; Wong, Timothy; Beniot, Gilles J.; Ouderkirk, Andrew

    2016-09-01

    Over the past decade, 3M has developed a number of mobile projectors, with a goal towards providing the world's smallest, most efficient projection systems. Compact size and efficiency are required characteristics for projection systems used in mobile devices and more lately, in augmented reality systems. In this paper we summarize the main generations of 3M light engine optical designs. We present the optical architectures of four light engines, including the rationale behind the illumination designs and the projection systems. In particular, we describe various configurations relating to the 3M polarizing beam splitter (PBS) which is key to enhanced efficiency of the miniature projection systems.

  10. Optical Properties of Small Ice Crystals with Black Carbon Inclusions

    Science.gov (United States)

    Yang, X.; Geier, M.; Arienti, M.

    2013-12-01

    The optical properties of ice crystals play a fundamental role in modeling atmospheric radiation and hydrological cycle, which are critical in monitoring climate change. While Black Carbon (BC) is recognized as the dominant absorber with positive radiative forcing (warming) (Ramanathan & Carmichael, 2008), in-situ observations (Cappa, et al, 2012) indicate that the characterization of the mixing state of BC with ice crystals and other non-BC particles in global climate models (Ghan & Schwartz, 2007) needs further investigation. The limitation in the available mixing models is due to the drastically different absorbing properties of BC compared to other aerosols. We explore the scattering properties of ice crystals (in shapes commonly found in cirrus clouds and contrails - Yang, et al. 2012) with the inclusion of BC particles. The Discrete Dipole Approximation (DDA) (Yurkin & Hoekstra, 2011) is utilized to directly calculate the optical properties of the crystals with multiple BC inclusions, modeled as a distribution of spheres. The results are then compared with the most popular models of internal and external mixing (Liou, et al. 2011). The DDA calculations are carried out over a broad range of BC particle sizes and volume fractions within the crystal at the 532 nm wavelength and for ice crystals smaller than 50 μm. The computationally intensive database generated in this study is critical for understanding the effect of different types of BC inclusions on the atmosphere radiative forcing. Examples will be discussed to illustrate the modification of BC optical properties by encapsulation in ice crystals and how the parameterization of the BC mixing state in global climate models can be improved. Acknowledgements Support by Sandia National Laboratories' LDRD (Laboratory Directed Research and Development) is gratefully acknowledged. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of

  11. Optical properties of monodispersive FePt nanoparticle films

    Energy Technology Data Exchange (ETDEWEB)

    Lee, S.J.; Lo, C.C.H. [Ames Laboratory, Iowa State University, Ames, IA 50011 (United States); Yu, A.C.C. [Sony Corporation, Sendai Technology Center, 3-4-1 Sakuragi, Miyagi 985-0842 (Japan); Fan, M. [Center for Sustainable Environmental Technologies, Iowa State University, Ames, IA 50011 (United States)

    2004-10-01

    The optical properties of monodispersive FePt nanoparticle films were investigated using spectroscopic ellipsometry in the energy range of 1.5 to 5.5 eV. The monodispersive FePt nanoparticle film was stabilized on a Si substrate by means of an organosilane coupling film, resulting in the formation of a (Si/SiO{sub 2}/APTS/FePt nanoparticles monolayer) structure. Multilayer optical models were employed to study the contribution of the FePt nanoparticles to the measured optical properties of the monodispersive FePt nanoparticle film, and to estimate the optical properties of the FePt nanoparticle layer. (copyright 2004 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  12. Potential application of Chinese traditional medicine (CTM) as enhancer for tissue optical clearing

    Science.gov (United States)

    Chen, Wei; Jiang, Jingying; Wang, Ruikang K.; Xu, Kexin

    2009-02-01

    Many biocompatible hyperosmotic agents such as dimethyl sulfoxide(DMSO) have been used as enhancers for tissue optical clearing technique. However, previous investigations showed that DMSO can induce bradycardia, respiratory problems, and alterations in blood pressure. Also, DMSO could potentially alter the chemical structure, and hence the functional properties, of cell membranes. In this talk, Borneol among natural and nontoxic CTMs was introduced as new enhancer for optical clearing of porcine skin tissue since it has been widely used as new penetration promoter in the field of trandermial drug delivery system(TDDS) and been proved to be effective. In the first, the spectral characteristics of borneol was obtained and analyzed by Fourier Transformation Infrared (FTIR) spectrophotometer. And further experimental studies were performed to probe if borneol is capable of optical clearing of porcine skin tissue in vitro with near infrared spectroscopy, double integrating-spheres system and Inverse Adding-Doubling(IAD) algorithm. Spectral results show that light penetration depth into skin tissue got the increase. Meanwhile, absorption coefficient and scattering coefficient of porcine skin treated by borneol got the decrease during the permeation of Borneol. Therefore, Borneol could be potentially used as enhancer for tissue optical clearing to improve non-invasive light-based diagnostic and imaging techniques while practically optical application and clinical safety are under consideration.

  13. Enhanced Thermo-Optical Switching of Paraffin-Wax Composite Spots under Laser Heating.

    Science.gov (United States)

    Said, Asmaa; Salah, Abeer; Fattah, Gamal Abdel

    2017-05-12

    Thermo-optical switches are of particular significance in communications networks where increasingly high switching speeds are required. Phase change materials (PCMs), in particular those based on paraffin wax, provide wealth of exciting applications with unusual thermally-induced switching properties, only limited by paraffin's rather low thermal conductivity. In this paper, the use of different carbon fillers as thermal conductivity enhancers for paraffin has been investigated, and a novel structure based on spot of paraffin wax as a thermo-optic switch is presented. Thermo-optical switching parameters are enhanced with the addition of graphite and graphene, due to the extreme thermal conductivity of the carbon fillers. Differential Scanning Calorimetry (DSC) and Scanning electron microscope (SEM) are performed on paraffin wax composites, and specific heat capacities are calculated based on DSC measurements. Thermo-optical switching based on transmission is measured as a function of the host concentration under conventional electric heating and laser heating of paraffin-carbon fillers composites. Further enhancements in thermo-optical switching parameters are studied under Nd:YAG laser heating. This novel structure can be used in future networks with huge bandwidth requirements and electric noise free remote aerial laser switching applications.

  14. Thermal and optical properties of porous silicon

    Directory of Open Access Journals (Sweden)

    Silva A. Ferreira da

    2001-01-01

    Full Text Available Thermal diffusivity and optical absorption have been investigated for porous silicon, at room temperature, using photoacoustic spectroscopy. The experimental results obtained conform well with the existing studies recently published. The value obtained for thermal diffusivity is 0.045 ± 0.002 cm²/s.The absorption onsets show energy structures, differing from the ordinary semiconductor of bulk type.

  15. Design of a Production Process to Enhance Optical Performance of 3(omega) Optics

    International Nuclear Information System (INIS)

    Prasad, R.R.; Bruere, J.R.; Halpin, J.; Lucero, P.; Mills, S.; Bernacil, M.; Hackel, R.P.

    2003-01-01

    Using the Phoenix pre-production conditioning facility we have shown that raster scanning of 3ω optics using a XeF excimer laser and mitigation of the resultant damage sites with a CO 2 laser can enhance their optical damage resistance. Several large-scale (43 cm x 43 cm) optics have been processed in this facility. A production facility capable of processing several large optics a week has been designed based on our experience in the pre-production facility. The facility will be equipped with UV conditioning lasers--351-nm XeF excimer lasers operating at 100 Hz and 23 ns. The facility will also include a CO 2 laser for damage mitigation, an optics stage for raster scanning large-scale optics, a damage mapping system (DMS) that images large-scale optics and can detect damage sites or precursors as small as ∼ 15 (micro)m, and two microscopes to image damage sites with ∼ 5 (micro)m resolution. The optics will be handled in a class 100 clean room, within the facility that will be maintained at class 1000

  16. Dispersion properties of plasma cladded annular optical fiber

    Science.gov (United States)

    KianiMajd, M.; Hasanbeigi, A.; Mehdian, H.; Hajisharifi, K.

    2018-05-01

    One of the considerable problems in a conventional image transferring fiber optic system is the two-fold coupling of propagating hybrid modes. In this paper, using a simple and practical analytical approach based on exact modal vectorial analysis together with Maxwell's equations, we show that applying plasma as a cladding medium of an annular optical fiber can remove this defect of conventional fiber optic automatically without any external instrument as the polarization beam splitter. Moreover, the analysis indicates that the presence of plasma in the proposed optical fiber could extend the possibilities for controlling the propagation property. The proposed structure presents itself as a promising route to advanced optical processing and opens new avenues in applied optics and photonics.

  17. Measuring optical properties of a blood vessel model using optical coherence tomography

    Science.gov (United States)

    Levitz, David; Hinds, Monica T.; Tran, Noi; Vartanian, Keri; Hanson, Stephen R.; Jacques, Steven L.

    2006-02-01

    In this paper we develop the concept of a tissue-engineered optical phantom that uses engineered tissue as a phantom for calibration and optimization of biomedical optics instrumentation. With this method, the effects of biological processes on measured signals can be studied in a well controlled manner. To demonstrate this concept, we attempted to investigate how the cellular remodeling of a collagen matrix affected the optical properties extracted from optical coherence tomography (OCT) images of the samples. Tissue-engineered optical phantoms of the vascular system were created by seeding smooth muscle cells in a collagen matrix. Four different optical properties were evaluated by fitting the OCT signal to 2 different models: the sample reflectivity ρ and attenuation parameter μ were extracted from the single scattering model, and the scattering coefficient μ s and root-mean-square scattering angle θ rms were extracted from the extended Huygens-Fresnel model. We found that while contraction of the smooth muscle cells was clearly evident macroscopically, on the microscopic scale very few cells were actually embedded in the collagen. Consequently, no significant difference between the cellular and acellular samples in either set of measured optical properties was observed. We believe that further optimization of our tissue-engineering methods is needed in order to make the histology and biochemistry of the cellular samples sufficiently different from the acellular samples on the microscopic level. Once these methods are optimized, we can better verify whether the optical properties of the cellular and acellular collagen samples differ.

  18. Enhanced optical performance of electrochemically etched porous silicon carbide

    International Nuclear Information System (INIS)

    Naderi, N; Hashim, M R; Saron, K M A; Rouhi, J

    2013-01-01

    Porous silicon carbide (PSC) was successfully synthesized via electrochemical etching of an n-type hexagonal silicon carbide (6H-SiC) substrate using various current densities. The cyclic voltammograms of SiC dissolution show that illumination is required for the accumulation of carriers at the surface, followed by surface oxidation and dissolution of the solid. The morphological and optical characterizations of PSC were reported. Scanning electron microscopy results demonstrated that the current density can be considered an important etching parameter that controls the porosity and uniformity of PSC; hence, it can be used to optimize the optical properties of the porous samples. (paper)

  19. Ring resonator systems to perform optical communication enhancement using soliton

    CERN Document Server

    Amiri, Iraj Sadegh

    2014-01-01

    The title explain new technique of secured and high capacity optical communication signals generation by using the micro and nano ring resonators. The pulses are known as soliton pulses which are more secured due to having the properties of chaotic and dark soliton signals with ultra short bandwidth. They have high capacity due to the fact that ring resonators are able to generate pulses in the form of solitons in multiples and train form. These pulses generated by ring resonators are suitable in optical communication due to use the compact and integrated rings system, easy to control, flexibi

  20. Optical properties of tetrapod nanostructured zinc oxide by chemical ...

    African Journals Online (AJOL)

    ... deposited onto indium tin oxide (ITO) coated glass substrate by thermal chemical vapor deposition (TCVD) technique. This work studies the effects of annealing temperature ranging from 100–500 ºC towards its physical and optical properties. FESEM images showed that the structural properties of tetrapod nanostructured ...

  1. Ex vivo investigation of tissue optical properties using an optical fibre sensor

    OpenAIRE

    Warncke, Dennis

    2014-01-01

    peer-reviewed Biomedical research has become a strong growing sector in recent years. Moreover the interdisciplinary background involves novel possibilities and measurement techniques. Light propagation in turbid media like human tissue is a central aspect to many medical and biomedical applications. This is a very complex process and depends on parameters, which are called optical properties. The spatial distribution of light is determined by those optical properties. A maj...

  2. Optical properties of multicomponent antimony-silver nanoclusters formed in silica by sequential ion implantation

    International Nuclear Information System (INIS)

    Zuhr, R.A.

    1995-11-01

    The linear and nonlinear optical properties of nanometer dimension metal colloids embedded in a dielectric depend explicitly on the electronic structure of the metal nanoclusters. The ability to control the electronic structure of the nanoclusters may make it possible to tailor the optical properties for enhanced performance. By sequential implantation of different metal ion species multi-component nanoclusters can be formed with significantly different optical properties than single element metal nanoclusters. The authors report the formation of multi-component Sb/Ag nanoclusters in silica by sequential implantation of Sb and Ag. Samples were implanted with relative ratios of Sb to Ag of 1:1 and 3:1. A second set of samples was made by single element implantations of Ag and Sb at the same energies and doses used to make the sequentially implanted samples. All samples were characterized using RBS and both linear and nonlinear optical measurements. The presence of both ions significantly modifies the optical properties of the composites compared to the single element nanocluster glass composites. In the sequentially implanted samples the optical density is lower, and the strong surface plasmon resonance absorption observed in the Ag implanted samples is not present. At the same time the nonlinear response of the these samples is larger than for the samples implanted with Sb alone, suggesting that the addition of Ag can increase the nonlinear response of the Sb particles formed. The results are consistent with the formation of multi-component Sb/Ag colloids

  3. Glancing angle deposited Al-doped ZnO nanostructures with different structural and optical properties

    Energy Technology Data Exchange (ETDEWEB)

    Yildiz, A., E-mail: yildizab@gmail.com [Department of Physics and Astronomy, University of Arkansas at Little Rock, Little Rock, AR 72204 (United States); Department of Energy Systems Engineering, Faculty of Engineering and Natural Sciences, Yıldırım Beyazıt University, Ankara (Turkey); Cansizoglu, H. [Department of Physics and Astronomy, University of Arkansas at Little Rock, Little Rock, AR 72204 (United States); Turkoz, M. [Department of Physics and Astronomy, University of Arkansas at Little Rock, Little Rock, AR 72204 (United States); Department of Electrical-Electronic Engineering, Faculty of Engineering, University of Karabuk, Karabuk (Turkey); Abdulrahman, R.; Al-Hilo, Alaa; Cansizoglu, M.F.; Demirkan, T.M.; Karabacak, T. [Department of Physics and Astronomy, University of Arkansas at Little Rock, Little Rock, AR 72204 (United States)

    2015-08-31

    Al-doped ZnO (AZO) nanostructure arrays with different shapes (tilted rods, vertical rods, spirals, and zigzags) were fabricated by utilizing glancing angle deposition (GLAD) technique in a DC sputter growth unit at room temperature. During GLAD, all the samples were tilted at an oblique angle of about 90° with respect to incoming flux direction. In order to vary the shapes of nanostructures, each sample was rotated at different speeds around the substrate normal axis. Rotation speed did not only affect the shape but also changed the microstructural and optical properties of GLAD AZO nanostructures. The experimental results reveal that GLAD AZO nanostructures of different shapes each have unique morphological, crystal structure, mechanical, and optical properties determined by scanning electron microscopy, X-ray diffraction, transmission, and reflectance measurements. Vertical nanorods display the largest grain size, minimum strain, lowest defect density, and highest optical transmittance compared to the other shapes. Growth dynamics of GLAD has been discussed to explain the dependence of structural and optical properties of nanostructures on the substrate rotation speed. - Highlights: • Al-doped ZnO (AZO) nanostructures with different shapes were fabricated. • They have unique morphological, crystal structure, and optical properties. • Vertical AZO nanorods show an enhanced optical transmittance.

  4. Fabrication of Au/graphene oxide/Ag sandwich structure thin film and its tunable energetics and tailorable optical properties

    OpenAIRE

    Ruijin Hong; Jialin Ji; Chunxian Tao; Daohua Zhang; Dawei Zhang

    2017-01-01

    Au/graphene oxide/Ag sandwich structure thin film was fabricated. The effects of graphene oxide (GO) and bimetal on the structure and optical properties of metal silver films were investigated by X-ray diffraction (XRD), optical absorption, and Raman intensity measurements, respectively. Compared to silver thin film, Au/graphene oxide/Ag sandwich structure composite thin films were observed with wider optical absorption peak and enhanced absorption intensity. The Raman signal for Rhodamine B ...

  5. Tunable enhanced optical absorption of graphene using plasmonic perfect absorbers

    Energy Technology Data Exchange (ETDEWEB)

    Cai, Yijun [Institute of Optoelectronic Technology, Department of Electronic Engineering, Xiamen University, Xiamen 361005 (China); Institute of Electromagnetics and Acoustics, Department of Electronic Science, Xiamen University, Xiamen 361005 (China); Zhu, Jinfeng, E-mail: nanoantenna@hotmail.com [Institute of Electromagnetics and Acoustics, Department of Electronic Science, Xiamen University, Xiamen 361005 (China); Liu, Qing Huo [Department of Electrical and Computer Engineering, Duke University, Durham, North Carolina 27708 (United States)

    2015-01-26

    Enhancement and manipulation of light absorption in graphene is a significant issue for applications of graphene-based optoelectronic devices. In order to achieve this purpose in the visible region, we demonstrate a design of a graphene optical absorber inspired by metal-dielectric-metal metamaterial for perfect absorption of electromagnetic waves. The optical absorbance ratios of single and three atomic layer graphene are enhanced up to 37.5% and 64.8%, respectively. The graphene absorber shows polarization-dependence and tolerates a wide range of incident angles. Furthermore, the peak position and bandwidth of graphene absorption spectra are tunable in a wide wavelength range through a specific structural configuration. These results imply that graphene in combination with plasmonic perfect absorbers have a promising potential for developing advanced nanophotonic devices.

  6. Nanoantennas for enhancing and confining the magnetic optical field

    Science.gov (United States)

    Grosjean, Thierry; Mivelle, Mathieu; Baida, Fadi I.; Burr, Geoffrey W.; Fischer, Ulrich C.

    2011-05-01

    We propose different optical antenna structures for enhancing and confining the magnetic optical field. A common feature of these structures are concave corners in thin metal films as locations of the enhanced magnetic field. This proposal is inspired by Babinet's principle as the concave edges are the complementary structures to convex metal corners, which are known to be locations of a strongly enhanced electric field. Bowtie antennas and the bowtie apertures of appropriate size were shown to exhibit resonances in the infrared frequency range with an especially strong enhancement of the electrical field in the gap between 2 convex metal corners. We show by numerical calculations, that the complementary structures, the complementary bowtie aperture - the diabolo antenna - and the complementary bow tie antenna - two closely spaced triangular apertures in a metal film with a narrow gap between two opposing concave corners - exhibit resonances with a strongly enhanced magnetic field at the narrow metal constriction between the concave corners. We suggest sub-wavelength circuits of concave and convex corners as building blocks of planar metamaterials.

  7. Magneto-Optical Properties of Paramagnetic Superrotors

    Science.gov (United States)

    Milner, A. A.; Korobenko, A.; Floß, J.; Averbukh, I. Sh.; Milner, V.

    2015-07-01

    We study the dynamics of paramagnetic molecular superrotors in an external magnetic field. An optical centrifuge is used to create dense ensembles of oxygen molecules in ultrahigh rotational states. In is shown, for the first time, that the gas of rotating molecules becomes optically birefringent in the presence of a magnetic field. The discovered effect of "magneto-rotational birefringence" indicates the preferential alignment of molecular axes along the field direction. We provide an intuitive qualitative model, in which the influence of the applied magnetic field on the molecular orientation is mediated by the spin-rotation coupling. This model is supported by the direct imaging of the distribution of molecular axes, the demonstration of the magnetic reversal of the rotational Raman signal, and by numerical calculations.

  8. Optical absorption enhancement by inserting ZnO optical spacer in plasmonic organic solar cells

    Science.gov (United States)

    N'Konou, Kekeli; Torchio, Philippe

    2018-01-01

    Optical absorption enhancement (AE) using coupled optical spacer and plasmonic effects in standard and inverted organic solar cells (OSCs) are demonstrated using the finite-difference time-domain numerical method. The influence of an added zinc oxide (ZnO) optical spacer layer inserted below the active layer in standard architecture is first theoretically investigated while the influence of varying the ZnO cathodic buffer layer thickness in inverted design is studied on AE. Then, the embedding of a square periodic array of core-shell silver-silica nanospheres (Ag@SiO2 NSs) at different positions in standard and inverted OSCs is performed while AE and short-circuit current density (Jsc) are calculated. As a result of previous combined effects, the optimized standard plasmonic OSCs present 15% and 79.45% enhancement in J over the reference with and without ZnO optical spacer layer, respectively, and a 16% increase of AE when Ag@SiO2 NSs are placed on top of the PEDOT:PSS layer. Compared to the inverted OSC reference, the plasmonic OSCs present 26% and 27% enhancement in J and AE, respectively, when the Ag@SiO2 NSs are located on top of the ZnO layer. Furthermore, the spatial position of these NSs in such OSCs is a key parameter for increasing light absorption via enhanced electromagnetic field distribution.

  9. Designing Optical Properties in DNA-Programmed Nanoparticle Superlattices

    Science.gov (United States)

    Ross, Michael Brendan

    A grand challenge of modern science has been the ability to predict and design the properties of new materials. This approach to the a priori design of materials presents a number of challenges including: predictable properties of the material building blocks, a programmable means for arranging such building blocks into well understood architectures, and robust models that can predict the properties of these new materials. In this dissertation, we present a series of studies that describe how optical properties in DNA-programmed nanoparticle superlattices can be predicted prior to their synthesis. The first chapter provides a history and introduction to the study of metal nanoparticle arrays. Chapter 2 surveys and compares several geometric models and electrodynamics simulations with the measured optical properties of DNA-nanoparticle superlattices. Chapter 3 describes silver nanoparticle superlattices (rather than gold) and identifies their promise as plasmonic metamaterials. In chapter 4, the concept of plasmonic metallurgy is introduced, whereby it is demonstrated that concepts from materials science and metallurgy can be applied to the optical properties of mixed metallic plasmonic materials, unveiling rich and tunable optical properties such as color and asymmetric reflectivity. Chapter 5 presents a comprehensive theoretical exploration of anisotropy (non-spherical) in nanoparticle superlattice architectures. The role of anisotropy is discussed both on the nanoscale, where several desirable metamaterial properties can be tuned from the ultraviolet to near-infrared, and on the mesoscale, where the size and shape of a superlattice is demonstrated to have a pronounced effect on the observed far-field optical properties. Chapter 6 builds upon those theoretical data presented in chapter 5, including the experimental realization of size and shape dependent properties in DNA-programmed superlattices. Specifically, nanoparticle spacing is explored as a parameter that

  10. Experimental and numerical study on the optical properties and agglomeration of nanoparticle suspensions

    Energy Technology Data Exchange (ETDEWEB)

    Otanicar, Todd, E-mail: todd-otanicar@utulsa.edu; Hoyt, Jordan; Fahar, Maryam [University of Tulsa, Department of Mechanical Engineering (United States); Jiang, Xuchuan [University of New South Wales, School of Materials Science and Engineering (Australia); Taylor, Robert A. [University of New South Wales, School of Mechanical and Manufacturing Engineering (Australia)

    2013-11-15

    Nanoparticles have garnered significant interest because of their ability to enhance greatly the optical properties of the base fluid in which they are suspended. The optical properties of nanoparticles are sensitive to the materials used, as well as to the host medium. Most fluids exhibit refractive indices that are highly temperature-dependent, resulting in nanoparticle suspensions which also exhibit temperature-dependent optical properties. Previous work has shown that temperature increases result in decreased absorption in nanoparticle suspensions. Here, we expand previous work to include core–shell particles due to the potential spectral shifts in optical properties that will arise from the base fluid with temperature changes and the role of agglomeration under temperature cycling through both experimental and numerical efforts. Thermal cycling tests for silica and gold, the constituents of the core–shell nanoparticles used in this study, were tested to determine the extent of particle agglomeration resulting from up to 200 accelerated heating cycles. Optical properties were recorded after heating two base fluids (water and ethylene glycol) with multiple surfactants for silver nanospheres and silica–gold core–shell nanoparticles. It was found that the temperature results in a small increase in the transmittance for both particle types and a blue shift in the spectral transmittance for core–shell nanoparticles. Further, the coupling effect of temperature and agglomeration played a significant role in determining both the spectral properties—particularly the resulting transmittance—of the silver nanoparticle suspensions.

  11. Frictional and Optical Properties of Diamond-Like-Carbon Coatings on Polycarbonate

    International Nuclear Information System (INIS)

    Lin Zeng; Gao Ding; Ba Dechun; Wang Feng; Liu Chunming

    2013-01-01

    In this work, diamond-like-carbon (DLC) films were deposited onto polycarbonate (PC) substrates by radio-frequency plasma-enhanced chemical vapor deposition (RF PECVD), and silicon films were prepared between DLC and PC substrates by magnetron sputtering deposition so as to improve the adhesion of the DLC films. The deposited films were investigated by means of field-emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. Subsequently, the following frictional and optical properties of the films were measured: the friction coefficient by using a ball-on-disk tribometer, the scratch hardness by using a nano-indenter, the optical transmittance by using a UV/visible spectrometer. The effects of incident power upon the frictional and optical properties of the films were investigated. Films deposited at low incident powers showed large optical gaps, which decreased with increasing incident power. The optical properties of DLC films correlated to the sp 2 content of the coatings. High anti-scratch properties were obtained at higher values of incident power. The anti-scratch properties of DLC films correlated to the sp 3 content of the coatings

  12. Linking Aerosol Optical Properties Between Laboratory, Field, and Model Studies

    Science.gov (United States)

    Murphy, S. M.; Pokhrel, R. P.; Foster, K. A.; Brown, H.; Liu, X.

    2017-12-01

    The optical properties of aerosol emissions from biomass burning have a significant impact on the Earth's radiative balance. Based on measurements made during the Fourth Fire Lab in Missoula Experiment, our group published a series of parameterizations that related optical properties (single scattering albedo and absorption due to brown carbon at multiple wavelengths) to the elemental to total carbon ratio of aerosols emitted from biomass burning. In this presentation, the ability of these parameterizations to simulate the optical properties of ambient aerosol is assessed using observations collected in 2017 from our mobile laboratory chasing wildfires in the Western United States. The ambient data includes measurements of multi-wavelength absorption, scattering, and extinction, size distribution, chemical composition, and volatility. In addition to testing the laboratory parameterizations, this combination of measurements allows us to assess the ability of core-shell Mie Theory to replicate observations and to assess the impact of brown carbon and mixing state on optical properties. Finally, both laboratory and ambient data are compared to the optical properties generated by a prominent climate model (Community Earth System Model (CESM) coupled with the Community Atmosphere Model (CAM 5)). The discrepancies between lab observations, ambient observations and model output will be discussed.

  13. Investigation of optical properties of Ag: PMMA nanocomposite structures

    Science.gov (United States)

    Ponelyte, S.; Palevicius, A.; Guobiene, A.; Puiso, J.; Prosycevas, I.

    2010-05-01

    In the recent years fundamental research involving the nanodimensional materials has received enormous momentum for observing and understanding new types of plasmonic materials and their physical phenomena occurring in the nanoscale. Mechanical and optical properties of these polymer based nanocomposite structures depend not only on type, dimensions and concentration of filler material, but also on a kind of polymer matrix used. By proper selection of polymer matrix and nanofillers, it is possible to engineer nanocomposite materials with certain favorable properties. One of the most striking features of nanocomposite materials is that they can expose unique optical properties that are not intrinsic to natural materials. In these researches, nanocomposite structures were formed using polymer (PMMA) as a matrix, and silver nanoparticles as fillers. By hot embossing procedure a diffraction grating was imprinted on formed layers. The effect of UV exposure time on nanocomposite structures morphology, optical (diffraction effectiveness, absorbance) and mechanical properties was investigated. Results were confirmed by UV-VIS spectrometer, Laser Diffractometer, PMT- 3 and AFM. Investigations proposed new nanocomposite structures as plasmonic materials with improved optical and mechanical properties, which may be applied for a number of technological applications: micro-electro-mechanical devices, optical devices, various plasmonic sensors, or even in DNA nanotechnology.

  14. Structural and optical properties of electro-optic material. Sputtered (Ba,Sr)TiO3

    International Nuclear Information System (INIS)

    Suzuki, Masato; Xu, Zhimou; Tanushi, Yuichiro; Yokoyama, Shin

    2006-01-01

    In order to develop a novel ring resonator optical switch, we have studied the structural and optical properties of the electro-optic material (Ba,Sr)TiO 3 (BST) deposited by RF sputtering on a SiO 2 cladding layer (1.0 μm). The crystallinity of the BST films is evaluated by X-ray diffraction and the optical propagation loss of the waveguides is measured using a He-Ne laser. As a result, it is found that there is a strong relationship between the optical propagation loss and crystallinity of the sputtered film. It is suggested that the propagating light is influenced by the crystal property, for example, the grain size and density of the polycrystalline BST film. (author)

  15. Optical properties of a multibarrier structure under intense laser fields

    Science.gov (United States)

    Ospina, D. A.; Akimov, V.; Mora-Ramos, M. E.; Morales, A. L.; Tulupenko, V.; Duque, C. A.

    2015-11-01

    Using the diagonalization method and within the effective mass and parabolic band approximations, the energy spectrum and the wave functions are investigated in biased multibarrier structure taking into account the effects of nonresonant intense laser fields. We calculated the optical properties from the susceptibility using a nonperturbative formalism recently reported. We study the changes in the intersubband optical absorption coefficients and refraction index for several values of the dressing laser parameter and for some specific values of the electric field applied along the growth direction of the heterostructure. It is concluded from our study that the peaks in the optical absorption spectrum have redshifts or blueshifts as a function of the laser parameter and the electric field. These parameters could be suitable tools for tuning the electronic and optical properties of the multibarrier structure.

  16. Enhancement Of Sensing Capabilities And Functionalization Of Optical Microresonators

    Science.gov (United States)

    Cocking, Alexander

    Optical microresonators have been demonstrated to provide a large enhancement in electric field by containing an resonant mode in a very small volume. This resonant enhancement is proportional to the quality of the resonator, which for microspheres has been demonstrated to be on the order of 1010. These devices can be leveraged to greatly improve light-matter interaction and for this reason the theoretical background of optical microresonators is discussed in the second chapter. This includes the use of COMSOL Multiphysics to model the mode structure and scattering from different resonator geometries. The second chapter also contains details on the fabrication and experimental design of optical microresonators. This includes the fabrication of fiber tapers for evanescent wave coupling into the devices. Once the theoretical framework for utilizing resonators as tools for enhancement has been established in the second chapter, we progress to the discussion of the microbubble geometry and its potential for use as an on-chip sensor system. Topics covered include design, fabrication, and theoretical analysis of the mode structure in this geometry. Modal interaction with a liquid filled microbubble is demonstrated. Additionally, the use of microbubble resonators as highly accurate temperature sensors is demonstrated experimentally and theoretically. In chapter 4 we investigate the use of silica microspheres as sensing devices; specifically, using them for the purpose of sensing nano-particles and chemicals in incredibly minute quantities. In this section microresonators are demonstrated to provide enhancement to Raman scattering from nano-scale particles. This configuration retains the traditional sensing methods of resonators by observing mode shifting and splitting in the resonance spectrum, while adding in a label-free sensing ability to determine material composition on adhered micro and nanoparticles. The fifth chapter discusses the characterization of a new class

  17. Thin Film Solar Cells and their Optical Properties

    Directory of Open Access Journals (Sweden)

    Stanislav Jurecka

    2006-01-01

    Full Text Available In this work we report on the optical parameters of the semiconductor thin film for solar cell applications determination. The method is based on the dynamical modeling of the spectral reflectance function combined with the stochastic optimization of the initial reflectance model estimation. The spectral dependency of the thin film optical parameters computations is based on the optical transitions modeling. The combination of the dynamical modeling and the stochastic optimization of the initial theoretical model estimation enable comfortable analysis of the spectral dependencies of the optical parameters and incorporation of the microstructure effects on the solar cell properties. The results of the optical parameters ofthe i-a-Si thin film determination are presented.

  18. Optical properties of zinc lead tellurite glasses

    Directory of Open Access Journals (Sweden)

    Salah Hassan Alazoumi

    2018-06-01

    Full Text Available Tellurite glass systems in the form of [ZnO]x [(TeO20.7-(PbO0.3]1-x with x = 0.15, 0.17, 0.20, 0.22 and 0.25 mol% were prepared using the melt quenching technique. XRD of the prepared samples have been measured for all samples. Both FTIR (280–4000 cm−1 and UV-Vis (200–800 nm spectra have been measured. Optical band gap and refractive index were calculated for every glass sample. Density of glass, molar volume and oxygen packing density (OPD were obtained. Values of the direct, indirect band gap ranged were found in the range 3.41–3.94 eV and 2.40–2.63 eV with increasing of ZnO concentration. Refractive index 2.58 and dielectric constant 6.66 were heigh at 17 ZnO mol% concentration. Molar polarizability, metallization criterion, polaron radius have been calculated for every glass composition. Keywords: Tellurite, Glass, Optical band gap, Refractive index

  19. Resonance Raman Optical Activity and Surface Enhanced Resonance Raman Optical Activity analysis of Cytochrome C

    DEFF Research Database (Denmark)

    Johannessen, Christian; Abdali, Salim; White, Peter C.

    2007-01-01

    High quality Resonance Raman (RR) and resonance Raman Optical Activity (ROA) spectra of cytochrome c were obtained in order to perform full assignment of spectral features of the resonance ROA spectrum. The resonance ROA spectrum of cytochrome c revealed a distinct spectral signature pattern due...... to resonance enhanced skeletal porphyrin vibrations, more pronounced than any contribution from the protein back-bone. Combining the intrinsic resonance enhancement of cytochrome c with surface plasmon enhancement by colloidal silver particles, the Surface Enhanced Resonance Raman Scattering (SERRS) and Chiral...... Enhanced Raman Spectroscopy (ChERS) spectra of the protein were successfully obtained at very low concentration (as low as 1 µM). The assignment of spectral features was based on the information obtained from the RR and resonance ROA spectra. Excellent agreement between RR and SERRS spectra is reported...

  20. Optical properties of amorphous silicon: Some problem areas

    International Nuclear Information System (INIS)

    Ravindra, N.M.; Chelle, F. de; Ance, C.; Ferraton, J.P.; Berger, J.M.; Coulibaly, S.P.

    1983-08-01

    In this presentation we essentially attempt to throw light on some problem areas concerning the various optical properties of amorphous silicon. The problems seem to emerge from the classical methods employed to determine the optical properties like the optical gap, urbach tail parameter and other related characteristics. Additional problems have emerged in recent years by virtue of many attempts to generalize the property-behaviour relationships for amorphous silicon without attributing any importance to the method of preparation of the films. It should be noted here that although many authors believe disorder to be the controlling parameter, we are of the opinion that at least for films containing fairly large concentrations of hydrogen, the hydrogen concentration has an equally important role to play. The present study has been carried out for films prepared by glow-discharge and chemical vapour deposition. (author)

  1. Measuring the optical properties of IceCube drill holes

    Directory of Open Access Journals (Sweden)

    Rongen Martin

    2016-01-01

    Full Text Available The IceCube Neutrino Observatory consists of 5160 digital optical modules (DOMs in a cubic kilometer of deep ice below the South Pole. The DOMs record the Cherenkov light from charged particles interacting in the ice. A good understanding of the optical properties of the ice is crucial to the quality of the event reconstruction. While the optical properties of the undisturbed ice are well understood, the properties of the refrozen drill holes still pose a challenge. A new data-acquisition and analysis approach using light originating from LEDs within one DOM detected by the photomultiplier of the same DOM will be described. This method allows us to explore the scattering length in the immediate vicinity of the considered DOMs.

  2. Observation and analysis of water inherent optical properties

    Science.gov (United States)

    Sun, Deyong; Li, Yunmei; Le, Chengfeng; Huang, Changchun

    2008-03-01

    Inherent optical property is an important part of water optical properties, and is the foundation of water color analytical model establishment. Through quantity filter technology (QFT) and backscattering meter BB9 (WETlabs Inc), absorption coefficients of CDOM, total suspended minerals and backscattering coefficients of total suspended minerals had been observed in Meiliang Bay of Taihu lake at summer and winter respectively. After analyzing the spectral characteristics of absorption and backscattering coefficients, the differences between two seasons had been illustrated adequately, and the reasons for the phenomena, which are related to the changes of water quality coefficient, had also been explained. So water environment states can be reflected by inherent optical properties. In addition, the relationship models between backscattering coefficients and suspended particle concentrations had been established, which can support coefficients for analytical models.

  3. Electronic structure and optical properties of AIN under high pressure

    International Nuclear Information System (INIS)

    Li Zetao; Dang Suihu; Li Chunxia

    2011-01-01

    We have calculated the electronic structure and optical properties of Wurtzite structure AIN under different high pressure with generalized gradient approximation (GGA) in this paper. The total energy, density of state, energy band structure and optical absorption and reflection properties under high pressure are calculated. By comparing the changes of the energy band structure, we obtained AIN phase transition pressure for 16.7 GPa, which is a direct band structure transforming to an indirect band structure. Meanwhile, according to the density of states distribution and energy band structure, we analyzed the optical properties of AIN under high-pressure, the results showed that the absorption spectra moved from low-energy to high-energy. (authors)

  4. Optical and structural properties of Cu-doped β-Ga2O3 films

    International Nuclear Information System (INIS)

    Zhang Yijun; Yan Jinliang; Li Qingshan; Qu Chong; Zhang Liying; Xie Wanfeng

    2011-01-01

    Graphical abstract: Highlights: → We prepare polycrystalline Cu-doped β-Ga2O3 films. → Cu dopants cause poor crystal quality and shrinkage of the optical band gap. → Cu-doping enhances the UV and blue emission. → A new blue emission peak centre at 475 nm appears by Cu-doping. → Cu dopants decrease the optical transmittance. - Abstract: The intrinsic and Cu-doped β-Ga 2 O 3 films were grown on Si and quartz substrates by RF magnetron sputtering in an argon and oxygen mixture ambient. The effects of the Cu doping and the post thermal annealing on the optical and structural properties of the β-Ga 2 O 3 films were studied. The surface morphology, microstructure, optical transmittance, optical absorption, optical energy gap and photoluminescence of the β-Ga 2 O 3 films were significantly changed after Cu-doping. After post thermal annealing, Polycrystalline β-Ga 2 O 3 films were obtained, the transmittance decreased. After Cu-doping, the grain size decreased, the crystal quality deteriorated and the optical band gap shrunk. The UV, blue and green emission bands were observed and discussed. The UV and blue emission were enhanced and a new blue emission peak centred at 475 nm appeared by Cu-doping.

  5. Effect of carrier doping and external electric field on the optical properties of graphene quantum dots

    Science.gov (United States)

    Basak, Tista; Basak, Tushima

    2018-02-01

    In this paper, we demonstrate that the optical properties of finite-sized graphene quantum dots can be effectively controlled by doping it with different types of charge carriers (electron/hole). In addition, the role played by a suitably directed external electric field on the optical absorption of charge-doped graphene quantum dots have also been elucidated. The computations have been performed on diamond-shaped graphene quantum dot (DQD) within the framework of the Pariser-Parr-Pople (PPP) model Hamiltonian, which takes into account long-range Coulomb interactions. Our results reveal that the energy band-gap increases when the DQD is doped with holes while it decreases on doping it with electrons. Further, the optical absorption spectra of DQD exhibits red/blue-shift on doping with electrons/holes. Our computations also indicate that the application of external transverse electric field results in a substantial blue-shift of the optical spectrum for charge-doped DQD. However, it is observed that the influence of charge-doping is more prominent in tuning the optical properties of finite-sized graphene quantum dots as compared to externally applied electric field. Thus, tailoring the optical properties of finite-sized graphene quantum dots by manipulative doping with charge carriers and suitably aligned external electric field can greatly enhance its potential application in designing nano-photonic devices.

  6. Electronic and optical properties of defect CdIn_2Te_4 chalcopyrite semiconductor: A first principle approach

    International Nuclear Information System (INIS)

    Mishra, S.; Ganguli, B.

    2016-01-01

    We present detailed study of structural, electronic and optical properties of CdIn_2Te_4 compound. The calculations are carried out using Density Functional theory based Tight Binding Linear Muffin Tin Orbital method. The compound is found to be direct band gap semiconductor with a band gap of 1.03 eV. The band gap is within the limit of LDA underestimation. The calculated structural parameters agree well with the available experimental values. We find a decrements of 9.6% in band gap and significant effects on overall electronic and optical properties due to structural distortions. These effects on optical properties come mainly from the change in transition probability. An-isotropic nature of optical properties get enhanced due to structural distortion. The Calculated real & imaginary parts of dielectric constant and static dielectric constant agree well with the available experimental result. - Highlights: • We present ab-initio calculations of electronic & optical properties of CdIn_2Te_4. • Band gap get reduced by 9.6% due to structural distortion. • Structural distortion has significant effects on optical properties. • Anisotropic nature of optical response functions get enhanced by structural distortion. • Calculated dielectric constant agrees with experimental value.

  7. Optical limiting properties of fullerenes and related materials

    Science.gov (United States)

    Riggs, Jason Eric

    Optical limiting properties of fullerene C60 and different C60 derivatives (methano-, pyrrolidino-, and amino-) towards nanosecond laser pulses at 532 nm were studied. The results show that optical limiting responses of the C60 derivatives are similar to those of the parent C60 despite their different linear absorption and emission properties. For C60 and the derivatives in room-temperature solutions of varying concentrations and optical path length, the optical limiting responses are strongly concentration dependent. The concentration dependence is not due to any optical artifacts since the results obtained under the same experimental conditions for reference systems show no such dependence. Similarly, optical limiting results of fullerenes are strongly dependent on the medium viscosity, with responses in viscous media weaker than that in room-temperature solutions. The solution concentration and medium viscosity dependencies are not limited to fullerenes. In fact, the results from a systematic investigation of several classes of nonlinear absorptive organic dyes show that the optical limiting responses are also concentration and medium viscosity dependent. Interestingly, however, such dependencies are uniquely absent in the optical limiting responses of metallophthalocyanines. In classical photophysics, the strong solution concentration and medium viscosity dependencies are indicative of significant contributions from photoexcited-state bimolecular processes. Thus, the experimental results are discussed in terms of a significantly modified five-level reverse saturable absorption mechanism. Optical limiting properties of single-walled and multiple-walled carbon nanotubes toward nanosecond laser pulses at 532 nm were also investigated. When suspended in water, the single-walled and multiple-walled carbon nanotubes exhibit essentially the same optical limiting responses, and the results are also comparable with those of carbon black aqueous suspension. For

  8. Functionality enhancement of industrialized optical fiber sensors and system developed for full-scale pavement monitoring.

    Science.gov (United States)

    Wang, Huaping; Liu, Wanqiu; He, Jianping; Xing, Xiaoying; Cao, Dandan; Gao, Xipeng; Hao, Xiaowei; Cheng, Hongwei; Zhou, Zhi

    2014-05-19

    Pavements always play a predominant role in transportation. Health monitoring of pavements is becoming more and more significant, as frequently suffering from cracks, rutting, and slippage renders them prematurely out of service. Effective and reliable sensing elements are thus in high demand to make prognosis on the mechanical properties and occurrence of damage to pavements. Therefore, in this paper, various types of functionality enhancement of industrialized optical fiber sensors for pavement monitoring are developed, with the corresponding operational principles clarified in theory and the performance double checked by basic experiments. Furthermore, a self-healing optical fiber sensing network system is adopted to accomplish full-scale monitoring of pavements. The application of optical fiber sensors assembly and self-healing network system in pavement has been carried out to validate the feasibility. It has been proved that the research in this article provides a valuable method and meaningful guidance for the integrity monitoring of civil structures, especially pavements.

  9. Functionality Enhancement of Industrialized Optical Fiber Sensors and System Developed for Full-Scale Pavement Monitoring

    Directory of Open Access Journals (Sweden)

    Huaping Wang

    2014-05-01

    Full Text Available Pavements always play a predominant role in transportation. Health monitoring of pavements is becoming more and more significant, as frequently suffering from cracks, rutting, and slippage renders them prematurely out of service. Effective and reliable sensing elements are thus in high demand to make prognosis on the mechanical properties and occurrence of damage to pavements. Therefore, in this paper, various types of functionality enhancement of industrialized optical fiber sensors for pavement monitoring are developed, with the corresponding operational principles clarified in theory and the performance double checked by basic experiments. Furthermore, a self-healing optical fiber sensing network system is adopted to accomplish full-scale monitoring of pavements. The application of optical fiber sensors assembly and self-healing network system in pavement has been carried out to validate the feasibility. It has been proved that the research in this article provides a valuable method and meaningful guidance for the integrity monitoring of civil structures, especially pavements.

  10. Optical properties of indium nitride films

    International Nuclear Information System (INIS)

    Tyagaj, V.A.; Evstigneev, A.M.; Krasiko, A.N.; Andreeva, A.F.; Malakhov, V.Ya.

    1977-01-01

    Reflection and transmission spectra of heavily doped indium nitride are studied at lambda=0.5-5 μm. Dispersion of the refractive index near the plasma resonance frequency, h.f. dielectric constant (epsilonsub(infinity)=9.3), and extinction coefficient near the transmission maximum of films have been determined from the analysis of interference pattern. The reflection spectrum exhibits maximum in the infrared range and optical effective mass is found through its position (msub(opt)*=0.11msub(0)). Free carrier absorption coefficient is shown to vary according to the law K approximately lambdasup(2.9+-0.1) which is characteristic of electron scattering by charged impurities. The analysis of absorption spectra near the threshold of interband transitions has lead to the conclusion that free carriers are localized in the lateral extremum of conduction band (or out of the center of the Brillouin zone), therefore the Burstein-Moss effect is absent

  11. Optical spectra and radio properties of quasars

    International Nuclear Information System (INIS)

    Wills, B.J.

    1982-01-01

    Using high quality spectrophotometric scans obtained at the McDonald Observatory, and data from the literature the author shows that, for quasars, the relative strength of optical Fe II emission (the broad blended feature lambda4570) may be roughly inversely proportional to line widths (full width at half maximum, FWHM). A similar relation between the relative intensity of the UV Fe II blend between 2300 and 2600 A (the lambda2500 feature) and the widths of Mg II and Hβ is shown. She distinguishes between compact and extended radio sources and includes radio quiet quasars, Seyfert 1 galaxies and BLRG's. The quasars associated with extended radio sources have the broadest emission lines and the weakest Fe II, falling close to the region occupied by BLRG's which also have extended radio structure. Those quasars with strong Fe II and compact radio structure are most similar to the Seyfert 1 galaxies. (Auth.)

  12. Strain induced optical properties of BaReO3

    Science.gov (United States)

    Kumavat, Sandip R.; Kansara, Shivam; Gupta, Sanjeev K.; Sonvane, Yogesh

    2018-05-01

    Here, we have performed strain induce optical properties of BaReO3 by using density functional theory (DFT). We noticed that after applying intrinsic and extrinsic strain to the BaReO3, it shows the metallic behavior. We also studied optical properties, which show good activity in the ultraviolet region. The results show that after applying intrinsic and extrinsic strain to BaReO3 the absorption peaks are shifted towards the high UV region of the spectrum. Thus, we concluded that, BaReO3 material with extrinsic strain can be useful for high frequency UV device and optoelectronic devices.

  13. Optical nonlinearity enhancement with graphene-decorated silicon waveguides

    Science.gov (United States)

    Ishizawa, Atsushi; Kou, Rai; Goto, Takahiro; Tsuchizawa, Tai; Matsuda, Nobuyuki; Hitachi, Kenichi; Nishikawa, Tadashi; Yamada, Koji; Sogawa, Tetsuomi; Gotoh, Hideki

    2017-04-01

    Broadband on-chip optical frequency combs (OFCs) are important for expanding the functionality of photonic integrated circuits. Here, we demonstrate a huge local optical nonlinearity enhancement using graphene. A waveguide is decorated with graphene by precisely manipulating graphene’s area and position. Our approach simultaneously achieves both an extremely efficient supercontinuum and ultra-short pulse generation. With our graphene-decorated silicon waveguide (G-SWG), we have achieved enhanced spectral broadening of femtosecond pump pulses, along with an eightfold increase in the output optical intensity at a wavelength approximately 200 nm shorter than that of the pump pulses. We also found that this huge nonlinearity works as a compressor that effectively compresses pulse width from 80 to 15.7 fs. Our results clearly show the potential for our G-SWG to greatly boost the speed and capacity of future communications with lower power consumption, and our method will further decrease the required pump laser power because it can be applied to decorate various kinds of waveguides with various two-dimensional materials.

  14. Linear and nonlinear optical properties of Sb-doped GeSe2 thin films

    Science.gov (United States)

    Zhang, Zhen-Ying; Chen, Fen; Lu, Shun-Bin; Wang, Yong-Hui; Shen, Xiang; Dai, Shi-Xun; Nie, Qiu-Hua

    2015-06-01

    Sb-doped GeSe2 chalcogenide thin films are prepared by the magnetron co-sputtering method. The linear optical properties of as-deposited films are derived by analyzing transmission spectra. The refractive index rises and the optical band gap decreases from 2.08 eV to 1.41 eV with increasing the Sb content. X-ray photoelectron spectra further confirm the formation of a covalent Sb-Se bond. The third-order nonlinear optical properties of thin films are investigated under femtosecond laser excitation at 800 nm. The results show that the third-order nonlinear optical properties are enhanced with increasing the concentration of Sb. The nonlinear refraction indices of these thin films are measured to be on the order of 10-18 m2/W with a positive sign and the nonlinear absorption coefficients are obtained to be on the order of 10-10 m/W. These excellent properties indicate that Sb-doped Ge-Se films have a good prospect in the applications of nonlinear optical devices. Project supported by the National Key Basic Research Program of China (Grant No. 2012CB722703), the National Natural Science Foundation of China (Grant No. 61377061), the Young Leaders of Academic Climbing Project of the Education Department of Zhejiang Province, China (Grant No. pd2013092), the Program for Innovative Research Team of Ningbo City, China (Grant No. 2009B217), and the K. C. Wong Magna Fund in Ningbo University, China.

  15. Manipulation of nanoparticles and biological samples through enhanced optical forces

    Science.gov (United States)

    Wilson, Benjamin

    Non-invasive optical manipulation of particles has emerged as a powerful and versatile tool for biological study and nanotechnology. We propose and demonstrate large scale nanoparticle assembly using opto-thermal force produced by conventional optical tweezers. This method is shown to allow precise concentration and assembly of particles including carbon-nanotubes, VO2 nanorods, and CdTe quantum dots. Assembled devices were shown to have good contact with patterned electrodes. In addition, we propose and demonstrate a purely optical approach to rotate and align particles using the interaction of polarized light with photonic crystal nanostructures to generate enhanced trapping force. With a weakly focused laser beam we observed efficient trapping and transportation of polystyrene beads with sizes ranging from 10 microm down to 190 nm as well as cancer cell nuclei. In addition, we demonstrated alignment of non-spherical particles using a 1-D photonic crystal structure. Bacterial cells were trapped, rotated and aligned with optical intensity as low as 17 microW/microm 2. This approach can be extended to using 2-D photonic crystal nanostructures for full rotation control.

  16. Graphene photonics for resonator-enhanced electro-optic devices and all-optical interactions

    Science.gov (United States)

    Englund, Dirk R.; Gan, Xuetao

    2017-03-21

    Techniques for coupling light into graphene using a planar photonic crystal having a resonant cavity characterized by a mode volume and a quality factor and at least one graphene layer positioned in proximity to the planar photonic crystal to at least partially overlap with an evanescent field of the resonant cavity. At least one mode of the resonant cavity can couple into the graphene layer via evanescent coupling. The optical properties of the graphene layer can be controlled, and characteristics of the graphene-cavity system can be detected. Coupling light into graphene can include electro-optic modulation of light, photodetection, saturable absorption, bistability, and autocorrelation.

  17. Distributed fiber optic sensing enhances pipeline safety and security

    Energy Technology Data Exchange (ETDEWEB)

    Frings, Jochen; Walk, Tobias [ILF Consulting Engineers, Munich (Germany)

    2011-09-15

    Pipelines are efficient, highly reliable and safe means of transportation. However, despite intensive right of way surveillance by foot, car and out of the air, pipeline leaks and illegal tappings are a reality - sometimes with catastrophic results. These events show a gap in real-time monitoring caused by the highly distributed nature of pipelines. Parts of this gap now can be closed with distributed fiber optic sensing technology. Using various physical effects this technology is apt to detect temperature, strain, vibrations and sound with very good localization over spans up to 50 km with a single sensor cable. Various field tested applications like leakage detection, third party activity monitoring and intrusion detection or ground movement detection as well as integrity monitoring proof that distributed fiber optic sensing can enhance pipeline safety and security. (orig.)

  18. Magneto-optical properties of binar ferrocolloids

    Science.gov (United States)

    Pshenichnikov, A. F.; Lebedev, A. V.; Lakhtina, E. V.; Stepanov, G. V.

    2018-03-01

    In this work, a new method for increasing optical anisotropy of a ferrocolloid through introducing the coiled polymer molecules or elongated nanosized non-magnetic particles is realized. Since the dimensions of structural elements comprising such a binary colloidal solution are small compared to the wavelength, the ferrocolloid remains optically homogeneous. Type I binary ferrocolloids are obtained by introducing polybutadiene molecules into a magnetic fluid (magnetite + kerosene + oleic acid). In this case, an increase in the double refraction (DR) is due to the deformation and stretching of the polymer coils along the magnetic field. In weak fields, double amplification of the signal was detected for the concentration of polymer molecules of about 0.5 %. A further increase in the concentration of impurity molecules weakens DR due to a disturbance of the sedimentation stability of the solution and precipitation of colloidal particles. Type II binary solution is synthesized on the basis of a magnetic fluid and rod-shaped impurity nanoparticles of goethite ( αFeOOH). The transverse dimension of the impurity particles (10 ‑ 30 nm) was close to the average diameter of single-domain magnetite particles, and the longitudinal dimension was an order of magnitude larger. An increase in the DR occurs due to the orientation of long axes of impurity particles along the magnetic field caused by the difference in the ”demagnetizing” coefficients along and across the axis of the particle. The magnetic double refraction has been studied depending on the concentration of magnetite and impurity particles and the strength of the magnetic field. For the first time, an experimental substantiation of the multiple amplification of the DR signal by impurity particles was obtained. In the fields (up to 10 kA/m) and for the volume fraction of impurity particles of the order of one percent, the DR signal is amplified by more than an order of magnitude. In stronger fields, the signal

  19. Enhanced optical coupling and Raman scattering via microscopic interface engineering

    Science.gov (United States)

    Thompson, Jonathan V.; Hokr, Brett H.; Kim, Wihan; Ballmann, Charles W.; Applegate, Brian E.; Jo, Javier A.; Yamilov, Alexey; Cao, Hui; Scully, Marlan O.; Yakovlev, Vladislav V.

    2017-11-01

    Spontaneous Raman scattering is an extremely powerful tool for the remote detection and identification of various chemical materials. However, when those materials are contained within strongly scattering or turbid media, as is the case in many biological and security related systems, the sensitivity and range of Raman signal generation and detection is severely limited. Here, we demonstrate that through microscopic engineering of the optical interface, the optical coupling of light into a turbid material can be substantially enhanced. This improved coupling facilitates the enhancement of the Raman scattering signal generated by molecules within the medium. In particular, we detect at least two-orders of magnitude more spontaneous Raman scattering from a sample when the pump laser light is focused into a microscopic hole in the surface of the sample. Because this approach enhances both the interaction time and interaction region of the laser light within the material, its use will greatly improve the range and sensitivity of many spectroscopic techniques, including Raman scattering and fluorescence emission detection, inside highly scattering environments.

  20. Nano-Structures for Optics and Photonics: Optical Strategies for Enhancing

    CERN Document Server

    Collins, John; Silvestri, Luciano

    2015-01-01

    The contributions in this volume were presented at a NATO Advanced Study Institute held in Erice, Italy, 4-19 July 2013. Many aspects of important research into nanophotonics, plasmonics, semiconductor materials and devices, instrumentation for bio sensing to name just a few, are covered in depth in this volume.  The growing connection between optics and electronics, due to the increasing important role plaid by semiconductor materials and devices, find their expression in the term photonics, which also reflects the importance of the photon aspect of light in the description of the performance of several optical systems. Nano-structures have unique capabilities that allow the enhanced performance of processes of interest in optical and photonic devices. In particular these structures permit the nanoscale manipulation of photons, electrons and atoms; they represent a very hot topic of research and are relevant to many devices and applications. The various subjects bridge over the disciplines of physics, biolo...

  1. FDTD simulations of near-field mediated semiconductor molecular optical properties

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Dai; Sakrow, Marcus; Mihaljevic, Josip; Meixner, Alfred J. [Institute of Physical and Theoretical Chemistry, University Tuebingen, Auf der Morgenstelle 8, Tuebingen (Germany)

    2010-07-01

    The optical properties of molecules can be dramatically altered when they are in a close proximity of an excited metal antenna. In order to get insight into how the antenna generated near-field influences the optical properties of low quantum yield molecules, we carried out FDTD simulations of a sharp laser-illuminated Au tip approaching to a semiconductor thin film. The time-averaged field distribution between the semiconductor thin film and the tip antenna is calculated regarding to different distances. Our calculation demonstrates that the coupling between the localized plasmon at the tip apex and semiconductor polariton can be achieved building up a distance-dependent high field enhancement. Our experimental results show that such a high field strength enhances not only the excitation process by a factor of 104, but alters the radiative: non-radiative decay rate giving approx. 15 times stronger photoluminescence emission.

  2. Optical properties of zinc lead tellurite glasses

    Science.gov (United States)

    Alazoumi, Salah Hassan; Aziz, Sidek Abdul; El-Mallawany, R.; Aliyu, Umar Sa'ad; Kamari, Halimah Mohamed; Zaid, Mohd Hafiz Mohd Mohd; Matori, Khamirul Amin; Ushah, Abdulbaset

    2018-06-01

    Tellurite glass systems in the form of [ZnO]x [(TeO2)0.7-(PbO)0.3]1-x with x = 0.15, 0.17, 0.20, 0.22 and 0.25 mol% were prepared using the melt quenching technique. XRD of the prepared samples have been measured for all samples. Both FTIR (280-4000 cm-1) and UV-Vis (200-800 nm) spectra have been measured. Optical band gap and refractive index were calculated for every glass sample. Density of glass, molar volume and oxygen packing density (OPD) were obtained. Values of the direct, indirect band gap ranged were found in the range 3.41-3.94 eV and 2.40-2.63 eV with increasing of ZnO concentration. Refractive index 2.58 and dielectric constant 6.66 were heigh at 17 ZnO mol% concentration. Molar polarizability, metallization criterion, polaron radius have been calculated for every glass composition.

  3. Optical modelling data for room temperature optical properties of organic–inorganic lead halide perovskites

    Directory of Open Access Journals (Sweden)

    Yajie Jiang

    2015-06-01

    Full Text Available The optical properties of perovskites at ambient temperatures are important both to the design of optimised solar cells as well as in other areas such as the refinement of electronic band structure calculations. Limited previous information on the optical modelling has been published. The experimental fitting parameters for optical constants of CH3NH3PbI3−xClx and CH3NH3PbI3 perovskite films are reported at 297 K as determined by detailed analysis of reflectance and transmittance data. The data in this study is related to the research article “Room temperature optical properties of organic–inorganic lead halide perovskites” in Solar Energy Materials & Solar Cells [1].

  4. Shift in optical properties of Mn doped CdS (A DFT+U study)

    Science.gov (United States)

    khan, M. Junaid Iqbal; Kanwal, Zarfishan; Nauman Usmani, M.

    2018-01-01

    Current study is based on PBE-GGA and GGA+U computational approach for calculating optical properties of Mn doped CdS. Cd atom in host CdS lattice (rocksalt structure) are substituted with Mn at various lattice positions and shift in optical properties is observed by increasing supercell size by employing PBE-GGA and Hubbard term. Optical properties vary with changing supercell size and show significant change for GGA+U. Blue shift in absorption spectrum and plots for PDOS, TDOS are in accordance with existing reported work. Moreover strong p-d hybridization is observed due to Mn and S orbital interactions and localization of d-states are scrutinized in vicinity of Fermi level or conduction band minima. GGA+U absorption curve shows redshift and a tremendous change in optical properties is observed due to different bonding. Doping Mn into CdS host lattice illustrates enhancement in Opto-electrical properties which maximizes CdS:Mn system scope in optoelectronic devices.

  5. Electronic properties and optical absorption of a phosphorene quantum dot

    Science.gov (United States)

    Liang, F. X.; Ren, Y. H.; Zhang, X. D.; Jiang, Z. T.

    2018-03-01

    Using the tight-binding Hamiltonian approach, we theoretically study the electronic and optical properties of a triangular phosphorene quantum dot (PQD) including one normal zigzag edge and two skewed armchair edges (ZAA-PQD). It is shown that the energy spectrum can be classified into the filled band (FB), the zero-energy band (ZB), and the unfilled band (UB). Numerical calculations of the FB, ZB, and UB probability distributions show that the FB and the UB correspond to the bulk states, while the ZB corresponds to the edge states, which appear on all of the three edges of the ZAA-PQD sharply different from the other PQDs. We also find that the strains and the electric fields can affect the energy levels inhomogeneously. Then the optical properties of the ZAA-PQD are investigated. There appear some strong low-energy optical absorption peaks indicating its sensitive low-energy optical response that is absent in other PQDs. Moreover, the strains and the electric fields can make inhomogeneous influences on the optical spectrum of the ZAA-PQD. This work may provide a useful reference for designing the electrical, mechanical, and optical PQD devices.

  6. Optical Properties of a-SiC:H Films Deposited by Glowdischarge Methods

    Directory of Open Access Journals (Sweden)

    Lusitra Munisa

    2003-12-01

    Full Text Available he optical properties of amorphous silicon carbon films deposited by glowdischarge method have been studied using ultra violet-visible (uv-vis spectroscopy. The refractive index was calculated by Swanepoel’s formula using transmission data then followed by numerical simulation. The films density tends to decrease with increasing carbon content. The widening of the optical gap by increasing carbon content indicates the enhancement of film’s transparence. Both real and imaginary parts of the dielectric constant show variation in magnitude as the carbon content increase.

  7. Structure, Electronic and Nonlinear Optical Properties of Furyloxazoles and Thienyloxazoles

    International Nuclear Information System (INIS)

    Dagli, Ozlem; Gok, Rabia; Bahat, Mehmet; Ozbay, Akif

    2016-01-01

    Geometry optimization, electronic and nonlinear optical properties of isomers of furyloxazole and thienyloxazole molecules are carried out at the B3LYP/6-311++G(2d,p) level. The conformational analysis of 12 compounds have been studied as a function of torsional angle between rings. Electronic and NLO properties such as dipole moment, energy gap, polarizability and first hyperpolarizability were also calculated. (paper)

  8. Ion-optical properties of Wien's filters with inhomogeneous fields

    International Nuclear Information System (INIS)

    Golikov, Yu.K.; Matyshev, A.A.; Solov'ev, K.V.

    1991-01-01

    Common conditions of beam stigmatic focusing in the Wien filters with direct axial trajectory in arbitrary two-dimensional inhomogeneous crossed electrical magnetic fields are obtained. Coefficients for geometrical aberrations of the second order of the crossed field system, characterized by stigmatic focusing properties, are found. Possibility of synthesis on the basis of the developed field system theory with required ion-optical properties is shown

  9. Optically enhanced nuclear cross polarization in acridine-doped fluorene

    Energy Technology Data Exchange (ETDEWEB)

    Oshiro, C.M.

    1982-06-01

    The objective of this work has been to create large polarizations of the dilute /sup 13/C nuclei in the solid state. The idea was to create /sup 1/H polarizations larger than Boltzmann and to use the proton enhanced nuclear induction spectroscopy cross polarization technique to then transfer this large polarization to the /sup 13/C spin system. Optical Nuclear Polarization (ONP) of acridine-doped fluorene single crystals was studied. In addition, ONP of powdered samples of the acridine-doped fluorene was studied. In general, many compounds do not crystallize easily or do not form large crystals suitable for NMR experiments. Powdered, amorphous and randomly dispersed samples are generally far more readily available than single crystals. One objective of this work has been to (first) create large /sup 1/H polarizations. Although large optical proton polarizations in single crystals have been reported previously, optically generated polarizations in powdered samples have not been reported. For these reasons, ONP studies of powdered samples of the acridine-doped fluorene were also undertaken. Using ONP in combination with the proton enhanced nuclear induction spectroscopy experiment, large /sup 13/C polarizations have been created in fluorene single crystals. These large /sup 13/C polarizations have permitted the determination of the seven incongruent chemical shielding tensors of the fluorene molecule. Part 2 of this thesis describes the proton enhanced nuclear induction spectroscopy experiment. Part 3 describes the ONP experiment. Part 4 is a description of the experimental set-up. Part 5 describes the data analysis for the determination of the chemical shielding tensors. Part 6 presents the results of the ONP experiments performed in this work and the chemical shielding tensors determined.

  10. Optically enhanced nuclear cross polarization in acridine-doped fluorene

    International Nuclear Information System (INIS)

    Oshiro, C.M.

    1982-06-01

    The objective of this work has been to create large polarizations of the dilute 13 C nuclei in the solid state. The idea was to create 1 H polarizations larger than Boltzmann and to use the proton enhanced nuclear induction spectroscopy cross polarization technique to then transfer this large polarization to the 13 C spin system. Optical Nuclear Polarization (ONP) of acridine-doped fluorene single crystals was studied. In addition, ONP of powdered samples of the acridine-doped fluorene was studied. In general, many compounds do not crystallize easily or do not form large crystals suitable for NMR experiments. Powdered, amorphous and randomly dispersed samples are generally far more readily available than single crystals. One objective of this work has been to (first) create large 1 H polarizations. Although large optical proton polarizations in single crystals have been reported previously, optically generated polarizations in powdered samples have not been reported. For these reasons, ONP studies of powdered samples of the acridine-doped fluorene were also undertaken. Using ONP in combination with the proton enhanced nuclear induction spectroscopy experiment, large 13 C polarizations have been created in fluorene single crystals. These large 13 C polarizations have permitted the determination of the seven incongruent chemical shielding tensors of the fluorene molecule. Part 2 of this thesis describes the proton enhanced nuclear induction spectroscopy experiment. Part 3 describes the ONP experiment. Part 4 is a description of the experimental set-up. Part 5 describes the data analysis for the determination of the chemical shielding tensors. Part 6 presents the results of the ONP experiments performed in this work and the chemical shielding tensors determined

  11. Enhanced optical limiting effects of graphene materials in polyimide

    International Nuclear Information System (INIS)

    Gan, Yao; Feng, Miao; Zhan, Hongbing

    2014-01-01

    Three different graphene nanostructure suspensions of graphene oxide nanosheets (GONSs), graphene oxide nanoribbons (GONRs), and graphene oxide quantum dots (GOQDs) are prepared and characterized. Using a typical two-step method, the GONSs, GONRs, and GOQDs are incorporated into a polyimide (PI) matrix to synthesize graphene/PI composite films, whose nonlinear optical (NLO) and optical limiting (OL) properties are investigated at 532 nm in the nanosecond regime. The GONR suspension exhibits superior NLO and OL effects compared with those of GONSs and GOQDs because of its stronger nonlinear scattering and excited-state absorption. The graphene/PI composite films exhibit NLO and OL performance superior to that of their corresponding suspensions, which is attributed primarily to a combination of nonlinear mechanisms, charge transfer between graphene materials and PI, and the matrix effect

  12. Multiparameter fiber optic sensing system for monitoring enhanced geothermal systems

    Energy Technology Data Exchange (ETDEWEB)

    Challener, William A

    2014-12-04

    The goal of this project was to design, fabricate and test an optical fiber cable which supports multiple sensing modalities for measurements in the harsh environment of enhanced geothermal systems. To accomplish this task, optical fiber was tested at both high temperatures and strains for mechanical integrity, and in the presence of hydrogen for resistance to darkening. Both single mode (SM) and multimode (MM) commercially available optical fiber were identified and selected for the cable based on the results of these tests. The cable was designed and fabricated using a tube-within-tube construction containing two MM fibers and one SM fiber, and without supporting gel that is not suitable for high temperature environments. Commercial fiber optic sensing instruments using Raman DTS (distributed temperature sensing), Brillouin DTSS (distributed temperature and strain sensing), and Raleigh COTDR (coherent optical time domain reflectometry) were selected for field testing. A microelectromechanical systems (MEMS) pressure sensor was designed, fabricated, packaged, and calibrated for high pressure measurements at high temperatures and spliced to the cable. A fiber Bragg grating (FBG) temperature sensor was also spliced to the cable. A geothermal well was selected and its temperature and pressure were logged. The cable was then deployed in the well in two separate field tests and measurements were made on these different sensing modalities. Raman DTS measurements were found to be accurate to ±5°C, even with some residual hydrogen darkening. Brillouin DTSS measurements were in good agreement with the Raman results. The Rayleigh COTDR instrument was able to detect some acoustic signatures, but was generally disappointing. The FBG sensor was used to determine the effects of hydrogen darkening, but drift over time made it unreliable as a temperature or pressure sensor. The MEMS sensor was found to be highly stable and accurate to better than its 0.1% calibration.

  13. Quasiparticle and optical properties of strained stanene and stanane.

    Science.gov (United States)

    Lu, Pengfei; Wu, Liyuan; Yang, Chuanghua; Liang, Dan; Quhe, Ruge; Guan, Pengfei; Wang, Shumin

    2017-06-20

    Quasiparticle band structures and optical properties of two dimensional stanene and stanane (fully hydrogenated stanene) are studied by the GW and GW plus Bethe-Salpeter equation (GW-BSE) approaches, with inclusion of the spin-orbit coupling (SOC). The SOC effect is significant for the electronic and optical properties in both stanene and stanane, compared with their group IV-enes and IV-anes counterparts. Stanene is a semiconductor with a quasiparticle band gap of 0.10 eV. Stanane has a sizable band gap of 1.63 eV and strongly binding exciton with binding energy of 0.10 eV. Under strain, the quasiparticle band gap and optical spectrum of both stanene and stanane are tunable.

  14. Peierls instability and optical properties of bilayer polyacene

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Longlong, E-mail: zhanglonglong@tyut.edu.cn [The College of Physics and Optoelectronics, Taiyuan University of Technology, Taiyuan 030024 (China); Xie, Shijie [School of Physics, Shandong University, Jinan 250100 (China)

    2017-05-03

    Highlights: • The Peierls instability of bilayer polyacene is discussed. • The external electric field effect on bilayer polyacene is discussed. • The pressure effect on bilayer polyacene is discussed. • The optical properties of bilayer polyacene are discussed. - Abstract: We reveal that bilayer polyacene can be the gapped state due to the intralayer Peierls instability. There are six topologically inequivalent Peierls-distorted structures and they are degenerate in energy. The external electric field can tune the Peierls gap and induce the semiconductor-to-metallic phase transitions. The optical conductivity spectra are calculated in an attempt to categorize the Peierls-distorted structures. The strength of the interlayer coupling essentially affects the electronic properties and the optical selection rules.

  15. Correlation between surface microstructure and optical properties of porous silicon

    Directory of Open Access Journals (Sweden)

    Saeideh Rhramezani Sani

    2007-12-01

    Full Text Available   We have studied the effect of increasing porosity and its microstructure surface variation on the optical and dielectric properties of porous silicon. It seems that porosity, as the surface roughness within the range of a few microns, shows quantum effect in the absorption and reflection process of porous silicon. Optical constants of porous silicon at normal incidence of light with wavelength in the range of 250-3000 nm have been calculated by Kramers-Kroning method. Our experimental analysis shows that electronic structure and dielectric properties of porous silicon are totally different from silicon. Also, it shows that porous silicon has optical response in the visible region. This difference was also verified by effective media approximation (EMA.

  16. Synthesis, field emission properties and optical properties of ZnSe nanoflowers

    Energy Technology Data Exchange (ETDEWEB)

    Xue, S.L., E-mail: slxue@dhu.edu.cn [Department of Applied Physics, College of Science, Donghua University, Shanghai 201620 (China); Wu, S.X.; Zeng, Q.Z.; Xie, P.; Gan, K.X.; Wei, J.; Bu, S.Y.; Ye, X.N.; Xie, L. [Department of Applied Physics, College of Science, Donghua University, Shanghai 201620 (China); Zou, R.J. [State Key Laboratory for Modification and Chemical Fibers and Polymer Materials, Donghua University, Shanghai 201620 (China); Zhang, C.M.; Zhu, P.F. [Department of Physics, School of Fundamental Studies, Shanghai University of Engineering Science, Shanghai 201620 (China)

    2016-03-01

    Graphical abstract: Unique ZnSe nanoflowers have been successfully synthesized by reaction of Se powder with Zn substrates. They are characterized by XRD, SEM, TEM, XPS, EDS and Raman spectroscopy and were single crystals with cubic zinc blende (ZB) structure. They also have excellent field emission properties and optical properties. - Highlights: • Novel ZnSe nanoflowers are grown on Zn foils. • ZnSe nanoflowers are characterized by XRD, SEM, TEM, XPS and Raman spectra. • ZnSe nanoflowers on Zn foils as cathodes possess good FE properties. - Abstract: ZnSe nanoflowers have been synthesized by reaction of Se powder with Zn substrates at low temperature. The as-prepared ZnSe nanoflowers were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), X-ray energy dispersive spectroscope (EDS) and Raman spectroscopy measurements. It was found that the morphologies of the as-prepared samples highly depended on reaction time. ZnSe nanoclusters and nanoflowers formed at 573 K when the reaction time was 20 and 60 min, respectively. The as-prepared ZnSe nanoflowers were composed of radically aligned ZnSe nanorods with smooth surfaces. The results of XRD, XPS, EDS, TEM and Raman showed that the as-prepared ZnSe nanocrystals were single crystals with cubic zinc blende (ZB) structure. The formation mechanism of the as-prepared ZnSe nanoflowers was also discussed. In addition, the as-prepared ZnSe nanoflowers had excellent electron emission properties. The turn-on field of the as-prepared ZnSe nanoflowers was 3.5 V/μm and the enhancement factor was 3499. The optical properties of the as-prepared ZnSe nanoflowers were also investigated. The results demonstrated that the as-prepared ZnSe nanoflowers were potential candidates for optoelectronic devices.

  17. Optical properties of infrared FELs from the FELI Facility II

    Energy Technology Data Exchange (ETDEWEB)

    Saeki, K.; Okuma, S.; Oshita, E. [Free Electron Laser Institute, Osaka (Japan)] [and others

    1995-12-31

    The FELI Facility II has succeeded in infrared FEL oscillation at 1.91 {mu} m using a 68-MeV, 40-A electron beam from the FELI S-band linac in February 27, 1995. The FELI Facility II is composed of a 3-m vertical type undulator ({lambda}u=3.8cm, N=78, Km a x=1.4, gap length {ge}20mm) and a 6.72-m optical cavity. It can cover the wavelength range of 1-5{mu}m. The FELs can be delivered from the optical cavity to the diagnostics room through a 40-m evacuated optical pipeline. Wavelength and cavity length dependences of optical properties such as peak power, average power, spectrum width, FEL macropulse, FEL transverse profile are reported.

  18. Effect of Zn doping on optical properties and photoconductivity of ...

    Indian Academy of Sciences (India)

    Keywords. Thin film; spray pyrolysis; tin sulfide; optical properties; photoluminescence; photoconductivity. 1. ... ber of compounds with CdI2 structure, has interesting proper- ties such .... STM images of 0, 2·5, 5 and 7·5 at% Zn-doped SnS2 films.

  19. Electrical and Optical Properties of Nanosized Perovskite-type La ...

    African Journals Online (AJOL)

    Electrical and Optical Properties of Nanosized Perovskite-type La 0.5 Ca 0.5 MO 3 (M=Co,Ni) ... In addition, the TEM images show that the average particle size of ... of both compounds decreases exponentially by increasing the temperature.

  20. Effect of Zn doping on optical properties and photoconductivity of ...

    Indian Academy of Sciences (India)

    Optical bandgap of the films have been calculated for different dopant concentrations and they lie in the region of 2.3–2.7 eV. Surprisingly, regardless of doping level, the luminescent properties of films are related to the fundamental bandgap energy and deep levels inside the bandgap. Photoconductivity of the films have ...

  1. Structural, elastic, electronic and optical properties of bi-alkali ...

    Indian Academy of Sciences (India)

    The structural parameters, elastic constants, electronic and optical properties of the bi-alkali ... and efficient method for the calculation of the ground-state ... Figure 2. Optimization curve (E–V) of the bi-alkali antimonides: (a) Na2KSb, (b) Na2RbSb, (c) Na2CsSb, .... ical shape of the charge distributions in the contour plots.

  2. Optical properties, ethylene production and softening in mango fruits

    NARCIS (Netherlands)

    Eccher Zerbini, P.C.; Vanoli, M.; Rizzolo, A.; Grassi, M.; Meirelles de Azevedo Pementel, A.; Spinelli, L.; Torricelli, A.

    2015-01-01

    Firmness decay, chlorophyll breakdown and carotenoid accumulation, controlled by ethylene, are major ripening events in mango fruit. Pigment content and tissue structure affect the optical properties of the mesocarp, which can be measured nondestructively in the intact fruit by time-resolved

  3. Synthesis, structural and optical properties of nanoparticles (Al, V ...

    Indian Academy of Sciences (India)

    The synthesis by the sol–gel method, structural and optical properties of ZnO, Zn0.99Al0.01O (AlZ),. Zn0.9V0.1O (VZ) ... drops of the resulting suspension containing the synthesized .... ZnO films on silicon substrate, they thought that this emis-.

  4. Electronic structure and optical properties of thorium monopnictides

    Indian Academy of Sciences (India)

    Unknown

    Indian Academy of Sciences. 165. Electronic structure and optical properties of thorium monopnictides. S KUMAR* and S AULUCK†. Physics Department, Institute of Engineering and Technology, M.J.P. Rohilkhand University, Bareilly 243 006,. India. †Department of Physics, Indian Institute of Technology, Roorkee 247 667, ...

  5. Electrical and optical properties of silicon-doped gallium nitride

    Indian Academy of Sciences (India)

    Si-doped GaN films in polycrystalline form were deposited on quartz substrates at deposition temperatures ranging from 300–623 K using r.f. sputtering technique. Electrical, optical and microstructural properties were studied for these films. It was observed that films deposited at room temperature contained mainly ...

  6. Properties of symbiotic stars from studies in the optical region

    International Nuclear Information System (INIS)

    Ciatti, F.

    1982-01-01

    The author uses observations of symbiotic stars in the optical region to discuss the following aspects: definition, photometric and spectroscopic evolution, the three-component model, evidence for the binary nature, spectroscopic properties and anomalies, single-star interpretations, the ''very slow novae'' and BQ// stars and a comparison of symbiotic stars with other classes. (C.F.)

  7. Optical and electrical properties of nickel xanthate thin films

    Indian Academy of Sciences (India)

    Administrator

    metal-xanthate thin films' production, nor their optical, electrical properties and .... vibration of –CH3 at 894 cm–1, (vii) the symmetric bend- ing vibration of C–O–C at 458 .... vity values are the two most important factors, affecting band width.

  8. Optical properties (bidirectional reflectance distribution function) of shot fabric

    NARCIS (Netherlands)

    Lu, Rong; Koenderink, Jan J.; Kappers, Astrid M L

    2000-01-01

    To study the optical properties of materials, one needs a complete set of the angular distribution functions of surface scattering from the materials. Here we present a convenient method for collecting a large set of bidirectional reflectance distribution function (BRDF) samples in the hemispherical

  9. Fabrication of Au/graphene oxide/Ag sandwich structure thin film and its tunable energetics and tailorable optical properties

    Directory of Open Access Journals (Sweden)

    Ruijin Hong

    2017-01-01

    Full Text Available Au/graphene oxide/Ag sandwich structure thin film was fabricated. The effects of graphene oxide (GO and bimetal on the structure and optical properties of metal silver films were investigated by X-ray diffraction (XRD, optical absorption, and Raman intensity measurements, respectively. Compared to silver thin film, Au/graphene oxide/Ag sandwich structure composite thin films were observed with wider optical absorption peak and enhanced absorption intensity. The Raman signal for Rhodamine B molecules based on the Au/graphene oxide/Ag sandwich nanostructure substrate were obviously enhanced due to the bimetal layer and GO layer with tunable absorption intensity and fluorescence quenching effects.

  10. Plasma-enhanced chemical vapor deposited silicon oxynitride films for optical waveguide bridges for use in mechanical sensors

    DEFF Research Database (Denmark)

    Storgaard-Larsen, Torben; Leistiko, Otto

    1997-01-01

    In this paper the influence of RF power, ammonia flow, annealing temperature, and annealing time on the optical and mechanical properties of plasma-enhanced chemically vapor deposited silicon oxynitride films, is presented. A low refractive index (1.47 to 1.48) film having tensile stress has been...

  11. Porous silicon: Synthesis and optical properties

    International Nuclear Information System (INIS)

    Naddaf, M.; Awad, F.

    2006-01-01

    Formation of porous silicon by electrochemical etching method of both p and n-type single crystal silicon wafers in HF based solutions has been performed by using three different modes. In addition to DC and pulsed voltage, a novel etching mode is developed to prepare light-emitting porous silicon by applying and holding-up a voltage in gradient steps form periodically, between the silicon wafer and a graphite electrode. Under same equivalent etching conditions, periodic gradient steps voltage etching can yield a porous silicon layer with stronger photoluminescence intensity and blue shift than the porous silicon layer prepared by DC or pulsed voltage etching. It has been found that the holding-up of the applied voltage during the etching process for defined interval of time is another significant future of this method, which highly affects the blue shift. This can be used for tailoring a porous layer with novel properties. The actual mechanism behind the blue shift is not clear exactly, even the experimental observation of atomic force microscope and purist measurements in support with quantum confinement model. It has been seen also from Fourier Transform Infrared study that interplays between O-Si-H and Si-H bond intensities play key role in deciding the efficiency of photoluminescence emission. Study of relative humidity sensing and photonic crystal properties of pours silicon samples has confirmed the advantages of the new adopted etching mode. The sensitivity at room temperature of porous silicon prepared by periodic gradient steps voltage etching was found to be about 70% as compared to 51% and 45% for the porous silicon prepared by DC and pulsed voltage etching, respectively. (author)

  12. Porous silicon: Synthesis and optical properties

    International Nuclear Information System (INIS)

    Naddaf, M.; Awad, F.

    2006-06-01

    Formation of porous silicon by electrochemical etching method of both p and n-type single crystal silicon wafers in HF based solutions has been performed by using three different modes. In addition to DC and pulsed voltage, a novel etching mode is developed to prepare light-emitting porous silicon by applying and holding-up a voltage in gradient steps form periodically, between the silicon wafer and a graphite electrode. Under same equivalent etching conditions, periodic gradient steps voltage etching can yield a porous silicon layer with stronger photoluminescence intensity and blue shift than the porous silicon layer prepared by DC or pulsed voltage etching. It has been found that the holding-up of the applied voltage during the etching process for defined interval of time is another significant future of this method, which highly affects the blue shift. This can be used for tailoring a porous layer with novel properties. The actual mechanism behind the blue shift is not clear exactly, even the experimental observation of atomic force microscope and purist measurements in support with quantum confinement model. It has been seen also from Fourier Transform Infrared study that interplays between O-Si-H and Si-H bond intensities play key role in deciding the efficiency of photoluminescence emission. Study of relative humidity sensing and photonic crystal properties of pours silicon samples has confirmed the advantages of the new adopted etching mode. The sensitivity at room temperature of porous silicon prepared by periodic gradient steps voltage etching was found to be about 70% as compared to 51% and 45% for the porous silicon prepared by DC and pulsed voltage etching, respectively. (author)

  13. Optical properties of arbuscular mycorrhizal fungal structures

    International Nuclear Information System (INIS)

    Perez, Adverdi; V-Hernandez, Alejandra; Rudamas, Carlos; Dreyer, Beatriz

    2008-01-01

    It was already reported by B. Dreyer at al. [1] that all fungal structures, both intra- and extra-radical fluoresced under blue light excitation regardless of their state (dead or alive). The source of the so called autofluorescence appears to be localized in the fungal cell wall. This supports the use of photoluminescence for the evaluation of AM colonization. However, the interpretation of these results is still in discussion [1-4]. In this work, arbuscular mycorrhizal spores were isolated from the rhizosphere of mango (Mangifera indica L.) plants by the method of wet sieving and decanting of Gerdemann and Nicolson [5] and studied by photoluminescence spectroscopy. Our experimental setup consists of an epifluorescence microscope (EM) coupled to a CCD-spectrometer through an arrangement of a home-made-telescope + fiber optic. This experimental setup allows the capture of images of the mycorrhizal structures (as usual in a standard epifluorescence microscope) combined with measurements of their corresponding emission bands. The preliminary results based on images obtained by standard EM do not clearly show that the emission is originated in the fungal cell walls as reported in Ref. 1. On the other hand, a very broad emission band in the visible part of the electromagnetic spectrum was observed in these spores by exciting at 450-490 nm and 300- 380 nm. We obtain a Full Width at Half Maximum (FWHM) of around 200 nm for this emission band whichis centered at 515 nm. This broad band seems to be composed of two narrower bands peaked around 494 and 547 nm and with FWHM of 50 nm and 150 nm, respectively. The profile of the observed emission band is in good agreement with the bands reported in Ref. 1 for vesicles, arbuscules and spores measured using the λ-Scan of a confocal laser scanning microscope. However, our results for spores show that the maxima of the narrower bands are shifted to higher energies in comparison to the corresponding bands observed in Ref. 1

  14. Enhancement of the transverse magneto-optical Kerr effect via resonant tunneling in trilayers containing magneto-optical metals

    Energy Technology Data Exchange (ETDEWEB)

    Girón-Sedas, J. A. [Departamento de Física, Universidad del Valle, AA 25360, Cali (Colombia); Centro de Investigación e Innovación en Bioinformática y Fotónica - CIBioFI, AA 25360 Cali (Colombia); Mejía-Salazar, J. R., E-mail: jrmejia3146@gmail.com [Instituto de Física de São Carlos, Universidade de São Paulo, CP 369, 13560-970 São Carlos, SP (Brazil); Moncada-Villa, E.; Porras-Montenegro, N. [Departamento de Física, Universidad del Valle, AA 25360, Cali (Colombia)

    2016-07-18

    We propose a way to enhance the transverse magneto-optical Kerr effect, by the excitation of resonant tunneling modes, in subwavelength trilayer structures featuring a dielectric slab sandwiched between two magneto-optical metallic layers. Depending on the magneto-optical layer widths, the proposed system may exhibit an extraordinary transverse magneto-optical Kerr effect, which makes it very attractive for the design and engineering of thin-film magneto-optical-based devices for future photonic circuits or fiber optical-communication systems.

  15. Optical properties of mesoporous photonic crystals, filled with dielectrics, ferroelectrics and piezoelectrics

    Directory of Open Access Journals (Sweden)

    V. S. Gorelik

    2017-12-01

    Full Text Available At present, it is very important to create new types of mirrors, nonlinear light frequency transformers and optical filters with controlled optical properties. In this connection, it is of great interest to study photonic crystals. Their dielectric permittivity varies periodically in space with a period permitting Bragg diffraction of light. In this paper, we have investigated the optical properties of mesoporous three-dimensional (3D opal-type and one-dimensional (1D anodic alumina photonic crystals, filled with different dielectrics, ferroelectrics and piezoelectrics. We have compared the optical properties of initial mesoporous photonic crystals and filled with different substances. The possibility of mesoporous photonic crystals using selective narrow-band light filters in Raman scattering experiments and nonlinear mirrors has been analyzed. The electromagnetic field enhancing in the case of exciting light frequency close to the stop band edges has been established. The optical harmonics and subharmonics generation in mesoporous crystals, filled with ferroelectrics and piezoelectrics was proposed.

  16. The investigation of Ce doped ZnO crystal: The electronic, optical and magnetic properties

    Science.gov (United States)

    Wen, Jun-Qing; Zhang, Jian-Min; Qiu, Ze-Gang; Yang, Xu; Li, Zhi-Qin

    2018-04-01

    The electronic, optical and magnetic properties of Ce doped ZnO crystal have been studied by using first principles method. The research of formation energies show that Ce doped ZnO is energetically stable, and the formation energies reduce from 6.25% to 12.5% for Ce molar percentage. The energy band is still direct band gap after Ce doped, and band gap increases with the increase of Cesbnd Ce distance. The Fermi level moves upward into conduction band and the DOS moves to lower energy with the increase of Ce concentration, which showing the properties of n-type semiconductor. The calculated optical properties imply that Ce doped causes a red-shift of absorption peaks, and enhances the absorption of the visible light. The transition from ferromagnetic to antiferromagnetic has been found in Ce doped ZnO.

  17. Exploring graphene superlattices: Magneto-optical properties

    Science.gov (United States)

    Duque, C. A.; Hernández-Bertrán, M. A.; Morales, A. L.; de Dios-Leyva, M.

    2017-02-01

    We present a detailed study of magnetic subbands, wave functions, and transition strengths for graphene superlattices (SLs) subject to a perpendicular magnetic field. It is shown that, for a weak magnetic field, the flat subbands of a SL exhibiting extra Dirac points are grouped into subsets, each of which consists of a singlet subband and a nearly degenerate doublet subband, and one nearly degenerate triplet subband. It was found that the wave functions corresponding to a singlet or to a doublet are always located around the image in real space of the central or extra Dirac points in k-space. The latter properties were explained by assuming that the electron motion is quasi-classical. Our study revealed that, for an intermediate field, the general characteristics of the wave functions are very similar to those of the pristine graphene, while for weak field, their behavior is drastically different. The latter is characterized by rapid oscillations which were understood using the solutions provided by the formalism of Luttinger-Kohn. The study on transition strengths allows us to obtain, for SLs with extra Dirac points in a weak magnetic field and different polarizations, the conditions under which transitions between multiplets are approximately allowed. It was shown that these conditions correspond to an unusual selection rule that is broken when the magnetic field intensity increases from weak to an intermediate value.

  18. Far- and near-field optical properties of gold nanoparticle ensembles

    Energy Technology Data Exchange (ETDEWEB)

    Nedyalkov, N N; Dikovska, A O; Dimitrov, I; Nikov, Ru; Atanasov, P A; Toshkova, R A; Gardeva, E G; Yossifova, L S; Alexandrov, M T

    2012-12-31

    The optical properties of gold nanoparticle clusters are presented from the point of view of their applications in biophotonics, where the absorption and scattering spectra are crucial. Generalised multiparticle Mie theory and finite difference time domain (FDTD) technique are used for theoretical description of the far- and nearfield optical properties of two dimensional nanoparticle ensembles. The system under consideration consists of spherical gold nanoparticles from 20 to 200 nm in diameter, forming 2D clusters in water. The properties of the far-field absorption and scattering spectra as a function of the cluster size, particle dimensions, and interparticle distance are investigated for ordered hexagonal structure of the particle arrays. It is found that the absorption efficiency can be shifted to the IR spectral range by increasing array size and decreasing interparticle distance. The increase in the array size also results in enhancement of the scattering efficiency while the absorption is reduced. The near-field intensity distribution is inhomogeneous over the array, as formation of zones with intensity enhancement of about two orders of magnitude is observed in specific areas. The optical properties of an ensemble whose configuration is reproduced from real experiments of gold nanoparticle deposition onto cancer cells are also presented. The results obtained can be used in designing of nanoparticle arrays with applications in biophotonics, bioimaging and photothermal therapy. (nanosystems)

  19. Far- and near-field optical properties of gold nanoparticle ensembles

    International Nuclear Information System (INIS)

    Nedyalkov, N N; Dikovska, A O; Dimitrov, I; Nikov, Ru; Atanasov, P A; Toshkova, R A; Gardeva, E G; Yossifova, L S; Alexandrov, M T

    2012-01-01

    The optical properties of gold nanoparticle clusters are presented from the point of view of their applications in biophotonics, where the absorption and scattering spectra are crucial. Generalised multiparticle Mie theory and finite difference time domain (FDTD) technique are used for theoretical description of the far- and nearfield optical properties of two dimensional nanoparticle ensembles. The system under consideration consists of spherical gold nanoparticles from 20 to 200 nm in diameter, forming 2D clusters in water. The properties of the far-field absorption and scattering spectra as a function of the cluster size, particle dimensions, and interparticle distance are investigated for ordered hexagonal structure of the particle arrays. It is found that the absorption efficiency can be shifted to the IR spectral range by increasing array size and decreasing interparticle distance. The increase in the array size also results in enhancement of the scattering efficiency while the absorption is reduced. The near-field intensity distribution is inhomogeneous over the array, as formation of zones with intensity enhancement of about two orders of magnitude is observed in specific areas. The optical properties of an ensemble whose configuration is reproduced from real experiments of gold nanoparticle deposition onto cancer cells are also presented. The results obtained can be used in designing of nanoparticle arrays with applications in biophotonics, bioimaging and photothermal therapy. (nanosystems)

  20. Annealed silver-islands for enhanced optical absorption in organic solar cell

    Energy Technology Data Exchange (ETDEWEB)

    Otieno, Francis, E-mail: frankotienoo@gmail.com [Material Physics Research Institute, School of Physics, University of the Witwatersrand, Private Bag 3, Wits, 2050Johannesburg (South Africa); Materials for Energy Research Group, University of the Witwatersrand, Private Bag 3, Wits, 2050 Johannesburg (South Africa); Airo, Mildred [School of Chemistry, University of the Witwatersrand, Private Bag 3, Wits, 2050 (South Africa); Ranganathan, Kamalakannan [School of Chemistry, University of the Witwatersrand, Private Bag 3, Wits, 2050 (South Africa); DST-NRF Centre of Strong Materials and the Molecular Sciences Institute, School of Chemistry, University of the Witwatersrand, 2193 Johannesburg (South Africa); Wamwangi, Daniel [Material Physics Research Institute, School of Physics, University of the Witwatersrand, Private Bag 3, Wits, 2050Johannesburg (South Africa); Materials for Energy Research Group, University of the Witwatersrand, Private Bag 3, Wits, 2050 Johannesburg (South Africa)

    2016-01-01

    Silver nano-islands are explored for enhancing optical absorption and photo-conversion efficiency in organic solar cells (OSCs) based on the surface plasmon resonance effect under diverse annealing conditions. Ag nano-islands have been deposited by RF magnetron sputtering at 15 W for 10 s and subsequently annealed between 100 °C–250 °C in air and Argon ambient. The optical properties of the reconstructed Ag islands demonstrate an increase and a blue shift in the absorption bands with increasing annealing temperature. This is the localized surface plasmon effect due to the Ag islands of diverse sizes, shapes and coverages. The increase in optical absorption with temperature is attributed to changes in island shape and density as collaborated by atomic force microscopy and TEM. As a proof of concept, an organic solar cell was characterized for current–voltage (I–V) measurements under dark and under solar simulated white light. Incorporation of annealed Ag islands has yielded an efficiency increment of between 4–24%. - Highlights: • RF Sputtering can be used to produce Ag NPs at low power. • Annealing enhances size, shape reconstruction as well as inter-particle separation. • Annealing in Argon ambient is more suitable than in air. • Ag NPs annealed at 250 °C enhances device absorption and PCE by up to 24%.

  1. Effect of substrate temperature and deposition rate on the morphology and optical properties of Ti films

    Energy Technology Data Exchange (ETDEWEB)

    Einollahzadeh-Samadi, M.; Dariani, R.S., E-mail: dariani@alzahra.ac.ir

    2013-09-01

    Titanium films are deposited on transparent fluorine-doped tin oxide (FTO) glass substrates by DC magnetron sputtering process. Influences imposed by sputtering rate and substrate temperature on surface morphology and optical properties of the deposited Ti films are investigated. We observed that all the sputtered films exhibit uniform and compact surface morphology without peeling and cracking. Morphology of the films is studied using atomic force microscopy (AFM) and X-ray diffraction (XRD). The optical properties of the films are investigated using UV–vis spectroscopy. The morphological studies indicate that by increasing the substrate temperature from room temperature to 250 °C and/or decreasing sputtering rate from 660 Å/min to 540 Å/min the surface roughness decreased from 73.4 to 31.0 nm and the grain size increases from 50.76 nm to 163.93 nm. An important effect of the root mean square (RMS) surface roughness and grain size is modification of the films optical properties. In fact, an enhancement of refractive index n for the Ti films deposited at high substrate temperature and/or high deposition rate is observed, that is attributed to reduction of RMS roughness. This effect is attributed to increment of fractional volume which leads to an increase in density of deposited film. Thus, by controlling the sputtering conditions one can reach to the desired morphological and optical properties.

  2. Improving Coastal Ocean Color Validation Capabilities through Application of Inherent Optical Properties (IOPs)

    Science.gov (United States)

    Mannino, Antonio

    2008-01-01

    Understanding how the different components of seawater alter the path of incident sunlight through scattering and absorption is essential to using remotely sensed ocean color observations effectively. This is particularly apropos in coastal waters where the different optically significant components (phytoplankton, detrital material, inorganic minerals, etc.) vary widely in concentration, often independently from one another. Inherent Optical Properties (IOPs) form the link between these biogeochemical constituents and the Apparent Optical Properties (AOPs). understanding this interrelationship is at the heart of successfully carrying out inversions of satellite-measured radiance to biogeochemical properties. While sufficient covariation of seawater constituents in case I waters typically allows empirical algorithms connecting AOPs and biogeochemical parameters to behave well, these empirical algorithms normally do not hold for case I1 regimes (Carder et al. 2003). Validation in the context of ocean color remote sensing refers to in-situ measurements used to verify or characterize algorithm products or any assumption used as input to an algorithm. In this project, validation capabilities are considered those measurement capabilities, techniques, methods, models, etc. that allow effective validation. Enhancing current validation capabilities by incorporating state-of-the-art IOP measurements and optical models is the purpose of this work. Involved in this pursuit is improving core IOP measurement capabilities (spectral, angular, spatio-temporal resolutions), improving our understanding of the behavior of analytical AOP-IOP approximations in complex coastal waters, and improving the spatial and temporal resolution of biogeochemical data for validation by applying biogeochemical-IOP inversion models so that these parameters can be computed from real-time IOP sensors with high sampling rates. Research cruises supported by this project provides for collection and

  3. Fe induced optical limiting properties of Zn1-xFexS nanospheres

    Science.gov (United States)

    Vineeshkumar, T. V.; Raj, D. Rithesh; Prasanth, S.; Unnikrishnan, N. V.; Mahadevan Pillai, V. P.; Sudarasanakumar, C.

    2018-02-01

    Zn1-xFexS (x = 0.00, 0.01, 0.03, 0.05) nanospheres were synthesized by polyethylene glycol assisted hydrothermal method. XRD studies revealed that samples of all concentrations exhibited cubic structure with crystallite grain size 7-9 nm. TEM and SEM show the formation of nanospheres by dense aggregation of smaller particles. Increasing Zn/Fe ratio tune the band gap from 3.4 to 3.2 eV and also quenches the green luminescence. FTIR spectra reveal the presence of capping agent, intensity variation and shifting of LO and TO phonon modes confirm the presence of Fe ions. Nonlinear optical properties were measured using open and closed aperture z-scan techniques, employing frequency doubled 532 nm pumping sources which indicated reverse saturable absorption (RSA) process. The nonlinear optical coefficients are obtained by two photon absorption (2PA). Composition dependent nonlinear optical coefficients ;β;, nonlinear refractive index, third order susceptibility and optical limiting threshold were estimated. The sample shows good nonlinear absorption and enhancement of optical limiting behavior with increasing Fe volume fraction. Contribution of RSA on optical nonlinearity of Zn1-xFexS nanospheres are also investigated using three different input energies. Zn1-xFexS with comparatively small limiting threshold value is a promising candidate for optical power limiting applications.

  4. Climatological aspects of aerosol optical properties in Northern Greece

    Directory of Open Access Journals (Sweden)

    E. Gerasopoulos

    2003-01-01

    Full Text Available Measurements of aerosol optical properties (aerosol optical depth, scattering and backscattering coefficients have been conducted at two ground-based sites in Northern Greece, Ouranoupolis (40° 23' N, 23° 57' E, 170 m a.s.l. and Thessaloniki (40° 38' N, 22° 57' E, 80 m a.s.l., between 1999 and 2002. The frequency distributions of the observed parameters have revealed the presence of individual modes of high and low values, indicating the influence from different sources. At both sites, the mean aerosol optical depth at 500 nm was 0.23. Values increase considerably during summer when they remain persistently between 0.3 and 0.5, going up to 0.7-0.8 during specific cases. The mean value of 65±40 Mm-1 of the particle scattering coefficient at 550 nm reflects the impact of continental pollution in the regional boundary layer. Trajectory analysis has shown that higher values of aerosol optical depth and the scattering coefficient are found in the east sector (former Soviet Union countries, eastern Balkan countries, whereas cleaner conditions are found for the NW direction. The influence of Sahara dust events is clearly reflected in the Ångström exponents. About 45-60% of the observed diurnal variation of the optical properties was attributed to the growth of aerosols with humidity, while the rest of the variability is in phase with the evolution of the sea-breeze cell. The contribution of local pollution is estimated to contribute 35±10% to the average aerosol optical depth at the Thessaloniki site during summer. Finally, the aerosol scale height (aerosol optical depth divided by scattering coefficient was found to be related to the height of the boundary layer with values between 0.5-1 km during winter and up to 2.5-3 km during summer.

  5. Thermotropic and optical properties of chiral nematic polymers

    International Nuclear Information System (INIS)

    Tsai, M.L.; Chen, S.H.; Marshall, K.L.; Jacobs, S.D.

    1988-09-01

    The thermotropic and optical properties of methacrylate copolymers and chemically modified poly(γ-benzyl L-glutamate) were investigated as part of our effort to explore the optical applications of these materials. It was found that besides the commonly cited comonomer ratio, physical blending and annealing followed by quenching represent a new and more flexible means to tune the selective reflection wavelength. In the poly (γ-benzyl L-glutamate) systems, it appears that the relatively high melt viscosity is capable of sustaining the cholesteric mesophase, generated by annealing and quenching, up to 100/degree/C. 22 refs., 8 figs

  6. Electronic structure and optical properties of solid C60

    International Nuclear Information System (INIS)

    Mattesini, M.; Ahuja, R.; Sa, L.; Hugosson, H.W.; Johansson, B.; Eriksson, O.

    2009-01-01

    The electronic structure and the optical properties of face-centered-cubic C 60 have been investigated by using an all-electron full-potential method. Our ab initio results show that the imaginary dielectric function for high-energy values looks very similar to that of graphite, revealing close electronic structure similarities between the two systems. We have also identified the origin of different peaks in the dielectric function of fullerene by means of the calculated electronic density of states. The computed optical spectrum compares fairly well with the available experimental data for the Vis-UV absorption spectrum of solid C 60 .

  7. Quantum Electrostatic Model for Optical Properties of Nanoscale Gold Films

    Directory of Open Access Journals (Sweden)

    Qian Haoliang

    2015-11-01

    Full Text Available The optical properties of thin gold films with thickness varying from 2.5 nm to 30 nm are investigated. Due to the quantum size effect, the optical constants of the thin gold film deviate from the Drude model for bulk material as film thickness decreases, especially around 2.5 nm, where the electron energy level becomes discrete. A theory based on the self-consistent solution of the Schrödinger equation and the Poisson equation is proposed and its predictions agree well with experimental results.

  8. Far-infrared properties of optically selected quasars

    International Nuclear Information System (INIS)

    Edelson, R.A.

    1986-01-01

    The far-infrared properties of 10, optically selected quasars were studied on the basis of pointed IRAS observations and ground-based near-infrared and radio measurements. Nine of these quasars were detected in at least three IRAS bands. The flat spectral energy distributions characterizing these optically selected quasars together with large 60-100-micron luminosities suggest that the infrared emission is dominated by nonthermal radiation. Seven of the nine quasars with far-infrared detections were found to have low-frequency turnovers. 12 references

  9. Exceptional points enhance sensing in an optical microcavity

    Science.gov (United States)

    Chen, Weijian; Kaya Özdemir, Şahin; Zhao, Guangming; Wiersig, Jan; Yang, Lan

    2017-08-01

    Sensors play an important part in many aspects of daily life such as infrared sensors in home security systems, particle sensors for environmental monitoring and motion sensors in mobile phones. High-quality optical microcavities are prime candidates for sensing applications because of their ability to enhance light-matter interactions in a very confined volume. Examples of such devices include mechanical transducers, magnetometers, single-particle absorption spectrometers, and microcavity sensors for sizing single particles and detecting nanometre-scale objects such as single nanoparticles and atomic ions. Traditionally, a very small perturbation near an optical microcavity introduces either a change in the linewidth or a frequency shift or splitting of a resonance that is proportional to the strength of the perturbation. Here we demonstrate an alternative sensing scheme, by which the sensitivity of microcavities can be enhanced when operated at non-Hermitian spectral degeneracies known as exceptional points. In our experiments, we use two nanoscale scatterers to tune a whispering-gallery-mode micro-toroid cavity, in which light propagates along a concave surface by continuous total internal reflection, in a precise and controlled manner to exceptional points. A target nanoscale object that subsequently enters the evanescent field of the cavity perturbs the system from its exceptional point, leading to frequency splitting. Owing to the complex-square-root topology near an exceptional point, this frequency splitting scales as the square root of the perturbation strength and is therefore larger (for sufficiently small perturbations) than the splitting observed in traditional non-exceptional-point sensing schemes. Our demonstration of exceptional-point-enhanced sensitivity paves the way for sensors with unprecedented sensitivity.

  10. Enhancement of mechanical properties of 123 superconductors

    Science.gov (United States)

    Balachandran, U.

    1995-04-25

    A composition and method are disclosed of preparing YBa{sub 2}Cu{sub 3}O{sub 7{minus}x} superconductor. Addition of tin oxide containing compounds to YBCO superconductors results in substantial improvement of fracture toughness and other mechanical properties without affect on T{sub c}. About 5-20% additions give rise to substantially improved mechanical properties.

  11. Enhancement of mechanical properties of 123 superconductors

    Science.gov (United States)

    Balachandran, Uthamalingam

    1995-01-01

    A composition and method of preparing YBa.sub.2 Cu.sub.3 O.sub.7-x superconductor. Addition of tin oxide containing compounds to YBCO superconductors results in substantial improvement of fracture toughness and other mechanical properties without affect on T.sub.c. About 5-20% additions give rise to substantially improved mechanical properties.

  12. Temperature-agile and structure-tunable optical properties of VO2/Ag thin films

    International Nuclear Information System (INIS)

    Zhang, X.R.; Hu, X.; Wang, W.; Zhao, Y.; Reinhardt, K.; Knize, R.J.; Lu, Yalin

    2012-01-01

    By integrating together VO 2 's unique near-room-temperature (RT) semiconductor-metal (S-M) phase transition with a thin silver (Ag) layer's plasmonic properties, VO 2 /Ag multilayers could present a much enhanced optical transmission change when increasing the temperature from RT to over VO 2 's S-M phase-transition temperature. Changing VO 2 and Ag layer thicknesses can also significantly tune their transmission and absorption properties, which could lead to a few useful designs in optoelectronic and energy-saving industries. (orig.)

  13. Some properties of point processes in statistical optics

    International Nuclear Information System (INIS)

    Picinbono, B.; Bendjaballah, C.

    2010-01-01

    The analysis of the statistical properties of the point process (PP) of photon detection times can be used to determine whether or not an optical field is classical, in the sense that its statistical description does not require the methods of quantum optics. This determination is, however, more difficult than ordinarily admitted and the first aim of this paper is to illustrate this point by using some results of the PP theory. For example, it is well known that the analysis of the photodetection of classical fields exhibits the so-called bunching effect. But this property alone cannot be used to decide the nature of a given optical field. Indeed, we have presented examples of point processes for which a bunching effect appears and yet they cannot be obtained from a classical field. These examples are illustrated by computer simulations. Similarly, it is often admitted that for fields with very low light intensity the bunching or antibunching can be described by using the statistical properties of the distance between successive events of the point process, which simplifies the experimental procedure. We have shown that, while this property is valid for classical PPs, it has no reason to be true for nonclassical PPs, and we have presented some examples of this situation also illustrated by computer simulations.

  14. Simulation of Terahertz Frequency Sources. Polar-Optical Phonon Enhancement of Harmonic Generation in Schottky Diodes

    National Research Council Canada - National Science Library

    Gelmont, Boris

    2002-01-01

    ... polar optical vibration frequency When a high frequency input signal is applied to a frequency multiplier device polar-optical phonons can enhance the non-linearities inherent in this device, enabling...

  15. Enhancing and quenching luminescence with gold nanoparticle films: the influence of substrate on the luminescent properties

    International Nuclear Information System (INIS)

    Guidelli, Eder José; Baffa, Oswaldo; Ramos, Ana Paula

    2016-01-01

    Gold nanoparticle (AuNP) films were sputtered over glass and aluminum substrates to enhance optically stimulated luminescence (OSL), a luminescent technique employed for radiation detection, from x-ray irradiated NaCl nanocrystals. The AuNP films deposited over glass led to enhanced-OSL emission, whereas the AuNP films deposited on aluminum substrates quenched the OSL emission. The enhanced-OSL intensity is proportional to the optical density of the film's plasmon resonance band at the stimulation wavelength. For the case of the AuNP/aluminum films, the luminescence quenching diminishes, and OSL intensity partially recovers upon increasing the distance between the AuNPs and the aluminum substrates, and between the luminescent nanocrystals and the AuNP films. These results suggest that plasmonic interactions between the emitter nanocrystals, the localized surface plasmons (LSP) of the AuNPs, and the substrate are responsible for the OSL enhancement and quenching. In this sense, the substrate dictates whether LSP relaxation occurs by radiative or non-radiative transisitions, leading to enhanced or quenched OSL, respectively. Therefore, besides showing that AuNP films can enhance and/or tune the sensitivity of luminescent radiation detectors, and demonstrating OSL as a new technique to investigate mechanisms of plasmon-enhanced luminescence, these results bring insights on how substrates strongly modify the optical properties of AuNP films. (paper)

  16. Modeling silica aerogel optical performance by determining its radiative properties

    Directory of Open Access Journals (Sweden)

    Lin Zhao

    2016-02-01

    Full Text Available Silica aerogel has been known as a promising candidate for high performance transparent insulation material (TIM. Optical transparency is a crucial metric for silica aerogels in many solar related applications. Both scattering and absorption can reduce the amount of light transmitted through an aerogel slab. Due to multiple scattering, the transmittance deviates from the Beer-Lambert law (exponential attenuation. To better understand its optical performance, we decoupled and quantified the extinction contributions of absorption and scattering separately by identifying two sets of radiative properties. The radiative properties are deduced from the measured total transmittance and reflectance spectra (from 250 nm to 2500 nm of synthesized aerogel samples by solving the inverse problem of the 1-D Radiative Transfer Equation (RTE. The obtained radiative properties are found to be independent of the sample geometry and can be considered intrinsic material properties, which originate from the aerogel’s microstructure. This finding allows for these properties to be directly compared between different samples. We also demonstrate that by using the obtained radiative properties, we can model the photon transport in aerogels of arbitrary shapes, where an analytical solution is difficult to obtain.

  17. Modeling silica aerogel optical performance by determining its radiative properties

    Science.gov (United States)

    Zhao, Lin; Yang, Sungwoo; Bhatia, Bikram; Strobach, Elise; Wang, Evelyn N.

    2016-02-01

    Silica aerogel has been known as a promising candidate for high performance transparent insulation material (TIM). Optical transparency is a crucial metric for silica aerogels in many solar related applications. Both scattering and absorption can reduce the amount of light transmitted through an aerogel slab. Due to multiple scattering, the transmittance deviates from the Beer-Lambert law (exponential attenuation). To better understand its optical performance, we decoupled and quantified the extinction contributions of absorption and scattering separately by identifying two sets of radiative properties. The radiative properties are deduced from the measured total transmittance and reflectance spectra (from 250 nm to 2500 nm) of synthesized aerogel samples by solving the inverse problem of the 1-D Radiative Transfer Equation (RTE). The obtained radiative properties are found to be independent of the sample geometry and can be considered intrinsic material properties, which originate from the aerogel's microstructure. This finding allows for these properties to be directly compared between different samples. We also demonstrate that by using the obtained radiative properties, we can model the photon transport in aerogels of arbitrary shapes, where an analytical solution is difficult to obtain.

  18. Airborne Lidar Measurements of Aerosol Optical Properties During SAFARI-2000

    Science.gov (United States)

    McGill, M. J.; Hlavka, D. L.; Hart, W. D.; Welton, E. J.; Campbell, J. R.; Starr, David OC. (Technical Monitor)

    2002-01-01

    The Cloud Physics Lidar (CPL) operated onboard the NASA ER-2 high altitude aircraft during the SAFARI-2000 field campaign. The CPL provided high spatial resolution measurements of aerosol optical properties at both 1064 nm and 532 nm. We present here results of planetary boundary layer (PBL) aerosol optical depth analysis and profiles of aerosol extinction. Variation of optical depth and extinction are examined as a function of regional location. The wide-scale aerosol mapping obtained by the CPL is a unique data set that will aid in future studies of aerosol transport. Comparisons between the airborne CPL and ground-based MicroPulse Lidar Network (MPL-Net) sites are shown to have good agreement.

  19. Lanthanides-clay nanocomposites: Synthesis, characterization and optical properties

    International Nuclear Information System (INIS)

    Celedon, Salvador; Quiroz, Carolina; Gonzalez, Guillermo; Sotomayor Torres, Clivia M.; Benavente, Eglantina

    2009-01-01

    Complexes of Europium(III) and Terbium(III) with 2,2-bipyridine and 1,10-phenanthroline were inserted into Na-bentonite by ion exchange reactions at room temperature. The products display interlaminar distances and stoichiometries in agreement with the ion exchange capacity and the interlayer space available in the clay. The optical properties of the intercalates, being qualitatively similar to those of the free complexes, are additionally improved with respect to exchange processes with the medium, especially in a moist environment. The protection again hydrolysis, together with the intensity of the optical transition 5 D 0 - 5 F 2 observed in the nanocomposite, makes these products promising for the development of novel optical materials

  20. Structural and optical properties of CdSe nanosheets

    Science.gov (United States)

    Solanki, Rekha Garg; Rajaram, P.; Arora, Aman

    2018-04-01

    Nanosheets of CdSe have been synthesized using a solvothermal route using citric acid as an additive. It is found that the citric acid effectively controls the structural and optical properties of CdSe nanostructures. XRD studies confirm the formation of hexagonal wurtzite phase of CdSe. The FESEM micrographs show that the obtained CdSe nanocrystals are in the form of very thin sheets (nanosheets). Optical absorption studies as well as Photoluminescence spectra show that the optical gap is around 1.76 eV which is close to the reported bulk value of 1.74 eV. The prepared CdSe nanosheets because of large surface area may be useful for catalytic activities in medicine, biotechnology and environmental chemistry and in biomedical imaging for in vitro detection of a breast cancer cells.

  1. Optical properties of polydimethylsiloxane (PDMS) during nanosecond laser processing

    Energy Technology Data Exchange (ETDEWEB)

    Stankova, N.E., E-mail: nestankova@yahoo.com [Institute of Electronics, Bulgarian Academy of Sciences, 72 Tsaridradsko shose Boul., Sofia 1784 (Bulgaria); Atanasov, P.A.; Nikov, Ru.G.; Nikov, R.G.; Nedyalkov, N.N.; Stoyanchov, T.R. [Institute of Electronics, Bulgarian Academy of Sciences, 72 Tsaridradsko shose Boul., Sofia 1784 (Bulgaria); Fukata, N. [International Center for Materials for NanoArchitectonics (MANA), National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba 305-0044 (Japan); Kolev, K.N.; Valova, E.I.; Georgieva, J.S.; Armyanov, St.A. [Rostislaw Kaischew Institute of Physical Chemistry, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Block 11, Sofia 1113 (Bulgaria)

    2016-06-30

    Highlights: • Ns-laser (266, 355, 532 and 1064 nm) processing of medical grade PDMS is performed. • Investigation of the optical transmittance as a function of the laser beam parameters. • Analyses of laser treated area by optical & laser microscope and μ-Raman spectrometry. • Application as (MEAs) neural interface for monitor and stimulation of neural activity. - Abstract: This article presents experimental investigations of effects of the process parameters on the medical grade polydimethylsiloxane (PDMS) elastomer processed by laser source with irradiation at UV (266 and 355 nm), VIS (532 nm) and NIR (1064 nm). Systematic experiments are done to characterize how the laser beam parameters (wavelength, fluence, and number of pulses) affect the optical properties and the chemical composition in the laser treated areas. Remarkable changes of the optical properties and the chemical composition are observed. Despite the low optical absorption of the native PDMS for UV, VIS and NIR wavelengths, successful laser treatment is accomplished due to the incubation process occurring below the polymer surface. With increasing of the fluence and the number of the pulses chemical transformations are revealed in the entire laser treated area and hence decreasing of the optical transmittance is observed. The incubation gets saturation after a certain number of pulses and the laser ablation of the material begins efficiently. At the UV and VIS wavelengths the number of the initial pulses, at which the optical transmittance begins to reduce, decreases from 16 up to 8 with increasing of the laser fluence up to 1.0, 2.5 and 10 J cm{sup −2} for 266, 355 and 532 nm, respectively. In the case of 1064 nm the optical transmittance begins to reduce at 11th pulse incident at a fluence of 13 J cm{sup −2} and the number of the pulses decreases to 8 when the fluence reaches value of 16 J cm{sup −2}. The threshold laser fluence needed to induce incubation process after certain

  2. Enhanced thermophysical properties via PAO superstructure

    Science.gov (United States)

    Pournorouz, Zahra; Mostafavi, Amirhossein; Pinto, Aditya; Bokka, Apparao; Jeon, Junha; Shin, Donghyun

    2017-01-01

    For the last few years, molten salt nanomaterials have attracted many scientists for their enhanced specific heat by doping a minute concentration of nanoparticles (up to 1% by weight). Likewise, enhancing the specific heat of liquid media is important in many aspects of engineering such as engine oil, coolant, and lubricant. However, such enhancement in specific heat was only observed for molten salts, yet other engineering fluids such as water, ethylene glycol, and oil have shown a decrease of specific heat with doped nanoparticles. Recent studies have shown that the observed specific heat enhancement resulted from unique nanostructures that were formed by molten salt molecules when interacting with nanoparticles. Thus, such enhancement in specific heat is only possible for molten salts because other fluids may not naturally form such nanostructures. In this study, we hypothesized such nanostructures can be mimicked through in situ formation of fabricated nano-additives, which are putative nanoparticles coated with useful organic materials (e.g., polar-group-ended organic molecules) leading to superstructures, and thus can be directly used for other engineering fluids. We first applied this approach to polyalphaolefin (PAO). A differential scanning calorimeter (DSC), a rheometer, and a customized setup were employed to characterize the heat capacity, viscosity, and thermal conductivity of PAO and PAO with fabricated nano-additives. Results showed 44.5% enhanced heat capacity and 19.8 and 22.98% enhancement for thermal conductivity and viscosity, respectively, by an addition of only 2% of fabricated nanostructures in comparison with pure PAO. Moreover, a partial melting of the polar-group-ended organic molecules was observed in the first thermal cycle and the peak disappeared in the following cycles. This indicates that the in situ formation of fabricated nano-additives spontaneously occurs in the thermal cycle to form nanostructures. Figure of merit analyses have

  3. Enhanced thermophysical properties via PAO superstructure.

    Science.gov (United States)

    Pournorouz, Zahra; Mostafavi, Amirhossein; Pinto, Aditya; Bokka, Apparao; Jeon, Junha; Shin, Donghyun

    2017-12-01

    For the last few years, molten salt nanomaterials have attracted many scientists for their enhanced specific heat by doping a minute concentration of nanoparticles (up to 1% by weight). Likewise, enhancing the specific heat of liquid media is important in many aspects of engineering such as engine oil, coolant, and lubricant. However, such enhancement in specific heat was only observed for molten salts, yet other engineering fluids such as water, ethylene glycol, and oil have shown a decrease of specific heat with doped nanoparticles. Recent studies have shown that the observed specific heat enhancement resulted from unique nanostructures that were formed by molten salt molecules when interacting with nanoparticles. Thus, such enhancement in specific heat is only possible for molten salts because other fluids may not naturally form such nanostructures. In this study, we hypothesized such nanostructures can be mimicked through in situ formation of fabricated nano-additives, which are putative nanoparticles coated with useful organic materials (e.g., polar-group-ended organic molecules) leading to superstructures, and thus can be directly used for other engineering fluids. We first applied this approach to polyalphaolefin (PAO). A differential scanning calorimeter (DSC), a rheometer, and a customized setup were employed to characterize the heat capacity, viscosity, and thermal conductivity of PAO and PAO with fabricated nano-additives. Results showed 44.5% enhanced heat capacity and 19.8 and 22.98% enhancement for thermal conductivity and viscosity, respectively, by an addition of only 2% of fabricated nanostructures in comparison with pure PAO. Moreover, a partial melting of the polar-group-ended organic molecules was observed in the first thermal cycle and the peak disappeared in the following cycles. This indicates that the in situ formation of fabricated nano-additives spontaneously occurs in the thermal cycle to form nanostructures. Figure of merit analyses have

  4. Local-field enhancement effect on the nonlinear optical response of gold-silver nanoplanets.

    Science.gov (United States)

    Cesca, T; Calvelli, P; Battaglin, G; Mazzoldi, P; Mattei, G

    2012-02-13

    We report on the nonlinear optical properties of Au-Ag nanoplanets produced by ion implantation and irradiation in silica, experimentally investigated by means of the single beam z-scan technique. The measurements provided experimental evidence of the intense local-field enhancement effect theoretically demonstrated for these plasmonic nanosystems. In particular, this has a dramatic impact on their nonlinear absorption behavior and results in a tunable changeover from reverse saturable absorption to saturable absorption by slightly varying the pump intensity and in the possibility to activate and observe nonlinear phenomena of the electron dynamics otherwise unaccessible in the intensity range that can be employed to study these materials. Finally, for the nanoplanet configuration we found a dramatic decrease of the intensity-dependent absorption coefficient, which could be very promising for obtaining optical gain materials.

  5. Optical properties of organic semiconductor thin films. Static spectra and real-time growth studies

    Energy Technology Data Exchange (ETDEWEB)

    Heinemeyer, Ute

    2009-07-20

    thickness dependence gives insight into possible mechanisms of these effects. Additional spatially resolved optical measurements are performed for studying in cooperation with D. Zhang et al. the microscopic optical properties of DIP films in detail, utilizing a tip-enhanced near field optical microscope. (orig.)

  6. Surface chemistry manipulation of gold nanorods preserves optical properties for bio-imaging applications

    Energy Technology Data Exchange (ETDEWEB)

    Polito, Anthony B.; Maurer-Gardner, Elizabeth I.; Hussain, Saber M., E-mail: saber.hussain@us.af.mil [Air Force Research Laboratory, Molecular Bioeffects Branch, Bioeffects Division, Human Effectiveness Directorate (United States)

    2015-12-15

    Due to their anisotropic shape, gold nanorods (GNRs) possess a number of advantages for biosystem use including, enhanced surface area and tunable optical properties within the near-infrared (NIR) region. However, cetyl trimethylammonium bromide-related cytotoxicity, overall poor cellular uptake following surface chemistry modifications, and loss of NIR optical properties due to material intracellular aggregation in combination remain as obstacles for nanobased biomedical GNR applications. In this article, we report that tannic acid-coated 11-mercaptoundecyl trimethylammonium bromide (MTAB) GNRs (MTAB-TA) show no significant decrease in either in vitro cell viability or stress activation after exposures to A549 human alveolar epithelial cells. In addition, MTAB-TA GNRs demonstrate a substantial level of cellular uptake while displaying a unique intracellular clustering pattern. This clustering pattern significantly reduces intracellular aggregation, preserving the GNRs NIR optical properties, vital for biomedical imaging applications. These results demonstrate how surface chemistry modifications enhance biocompatibility, allow for higher rate of internalization with low intracellular aggregation of MTAB-TA GNRs, and identify them as prime candidates for use in nanobased bio-imaging applications.Graphical Abstract.

  7. Composition dependence of the optical and structural properties of Eu-doped oxyfluoride glasses

    DEFF Research Database (Denmark)

    Zhu, C.F.; Wu, D.Q.; Zhang, Y.F.

    2015-01-01

    Europium doped oxyfluoride glasses were prepared by the melt quenching method for the light emitting diodes applications. The optical and structural properties of these glasses were studied by means of photoluminescence spectra, Commission Internationale de L'Eclairage chromaticity coordinates, X...... compositions. Finally, we propose a mechanism to explain how the glass structure affects the reduction of Eu ions as well as optical properties of the glasses.......Europium doped oxyfluoride glasses were prepared by the melt quenching method for the light emitting diodes applications. The optical and structural properties of these glasses were studied by means of photoluminescence spectra, Commission Internationale de L'Eclairage chromaticity coordinates, X...... on the base glass compositions. For certain base glass compositions, CaF2 crystals can form during the melt cooling process, and thereby enhance the conversion from Eu3+ to Eu2+. The formation of CaF2 crystals can be suppressed by adding CaO, Al2O3 and B2O3, but enhanced by adding Na2O and K2O in glass...

  8. Electrical and optical transport properties of single layer WSe2

    Science.gov (United States)

    Tahir, M.

    2018-03-01

    The electronic properties of single layer WSe2 are distinct from the famous graphene due to strong spin orbit coupling, a huge band gap and an anisotropic lifting of the degeneracy of the valley degree of freedom under Zeeman field. In this work, band structure of the monolayer WSe2 is evaluated in the presence of spin and valley Zeeman fields to study the electrical and optical transport properties. Using Kubo formalism, an explicit expression for the electrical Hall conductivity is examined at finite temperatures. The electrical longitudinal conductivity is also evaluated. Further, the longitudinal and Hall optical conductivities are analyzed. It is observed that the contributions of the spin-up and spin-down states to the power absorption spectrum depend on the valley index. The numerical results exhibit absorption peaks as a function of photon energy, ℏ ω, in the range ∼ 1.5 -2 eV. Also, the optical response lies in the visible frequency range in contrast to the conventional two-dimensional electron gas or graphene where the response is limited to terahertz regime. This ability to isolate carriers in spin-valley coupled structures may make WSe2 a promising candidate for future spintronics, valleytronics and optical devices.

  9. Structural and optical properties of furfurylidenemalononitrile thin films

    Science.gov (United States)

    Ali, H. A. M.

    2013-03-01

    Thin films of furfurylidenemalononitrile (FMN) were deposited on different substrates at room temperature by thermal evaporation technique under a high vacuum. The structure of the powder was confirmed by Fourier transformation infrared (FTIR) technique. The unit cell dimensions were determined from X-ray diffraction (XRD) studies. The optical properties were investigated using spectrophotometric measurements of the transmittance and reflectance at normal incidence of light in the wavelength range from 200 to 2500 nm. The refractive index (n), the absorption index (k) and the absorption coefficient (α) were calculated. The analysis of the spectral behavior of the absorption coefficient in the absorption region revealed an indirect allowed transition. The refractive index dispersion was analyzed using the single oscillator model. Some dispersion parameters were estimated. Complex dielectric function and optical conductivity were determined. The influence of the irradiation with high-energy X-rays (6 MeV) on the studied properties was also investigated.

  10. Correlated structure-optical properties studies of plasmonic nanoparticles

    International Nuclear Information System (INIS)

    Ringe, Emilie; Duyne, Richard P Van; Marks, Laurence D

    2014-01-01

    Interest in nanotechnology is driven by unprecedented means to tailor the physical behaviour via structure and composition. Unlike bulk materials, minute changes in size and shape can affect the optical properties of nanoparticles. Characterization, understanding, and prediction of such structure-function relationships is crucial to the development of novel applications such as plasmonic sensors, devices, and drug delivery systems. Such knowledge has been recently vastly expanded through systematic, high throughput correlated measurements, where the localized surface plasmon resonance (LSPR) is probed optically and the particle shape investigated with electron microscopy. This paper will address some of the recent experimental advances in single particle studies that provide new insight not only on the effects of size, composition, and shape on plasmonic properties but also their interrelation. Plasmon resonance frequency and decay, substrate effects, size, shape, and composition will be explored for a variety of plasmonic systems

  11. Optical properties of implanted Xe color centers in diamond

    Science.gov (United States)

    Sandstrom, Russell; Ke, Li; Martin, Aiden; Wang, Ziyu; Kianinia, Mehran; Green, Ben; Gao, Wei-bo; Aharonovich, Igor

    2018-03-01

    Optical properties of color centers in diamond have been the subject of intense research due to their promising applications in quantum photonics. In this work we study the optical properties of Xe related color centers implanted into nitrogen rich (type IIA) and an ultrapure, electronic grade diamond. The Xe defect has two zero phonon lines at ∼794 nm and 811 nm, which can be effectively excited using both green and red excitation, however, its emission in the nitrogen rich diamond is brighter. Near resonant excitation is performed at cryogenic temperatures and luminescence is probed under strong magnetic field. Our results are important towards the understanding of the Xe related defect and other near infrared color centers in diamond.

  12. Synthesis, Characterization, and Nonlinear Optical Properties of P-Substituted Poly Gamma-Benzyl

    Science.gov (United States)

    Choi, Dong-Hoon

    Poly gamma-benzyl-L-glutamate (PBLG), poly gamma-p-fluorobenzyl -L-glutamate (PGLU(pFB)), poly gamma -p-nitrobenzyl-L-glutamate (PGLU(pNB)), and poly gamma-p-trifluoromethylbenzyl-L-glutamate (PGLU(pTFMB)) have been synthesized. These PBLG polymers show variations in the side chain conformations in the solid state and solution state. In the solid state, the side chain orientation was assigned to a longitudinal or transverse direction by virtue of the polarized infrared spectrum of each PBLG analogue. The characteristics of the lyotropic liquid crystalline behavior could be observed. The optical waveguiding property of these polymers facilitated measurement of the refractive index and the thickness of each polymer film. Poling the polymer films and using the simple reflection technique, the electro -optic coefficients of the PBLG analogues could be determined. The effect of the para substitution on benzyl ester as it effected the electro-optic coefficient and the relation between the dielectric properties and the electro-optic effect of each polymer were investigated. These studies were able to demonstrate which conformation of the side chain in para substituted poly gamma-benzyl -L-glutamates is a more favorable conformation for enhancing the electro-optic behavior of these polymers.

  13. Optical enhancement effects of plasmonic nanostructures on organic photovoltaic cells

    KAUST Repository

    Park, Hui Joon

    2015-04-01

    © 2015 Hui Joon Park and L. Jay Guo. Published by Elsevier B.V. on behalf of Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences. All rights reserved. In this article, the optical enhancement effects of plasmonic nanostructures on OPV cells were reviewed as an effective way to resolve the mismatch problems between the short exciton diffusion length in organic semiconductors (around 10 nm) and the large thickness required to fully absorb sunlight (e.g. hundreds of nanometers). Especially, the performances of OPVs with plasmonic nanoparticles in photoactive and buffer layers and with periodic nanostructures were investigated. Furthermore, nanoimprint lithography-based nanofabrication processes that can easily control the dimension and uniformity of structures for large-area and uniform plasmonic nanostructures were demonstrated.

  14. Optical properties of CeO 2 thin films

    Indian Academy of Sciences (India)

    Cerium oxide (CeO2) thin films have been prepared by electron beam evaporation technique onto glass substrate at a pressure of about 6 × 10-6 Torr. The thickness of CeO2 films ranges from 140–180 nm. The optical properties of cerium oxide films are studied in the wavelength range of 200–850 nm. The film is highly ...

  15. Optical properties and electron transport in low-dimensional nanostructures

    Czech Academy of Sciences Publication Activity Database

    Král, Karel; Menšík, Miroslav

    2011-01-01

    Roč. 54, 2-2 (2011), s. 4-13 ISSN 0021-3411 R&D Projects: GA MŠk(CZ) OC10007 Institutional research plan: CEZ:AV0Z10100520; CEZ:AV0Z40500505 Keywords : quantum dots * electron -photon interaction * optical properties * electron relaxation * DNA molecule Subject RIV: BE - The oretical Physics http://elibrary.ru/contents.asp?issueid=1010336

  16. Optical properties of a single free standing nanodiamond

    Energy Technology Data Exchange (ETDEWEB)

    Sun, K W; Wang, C Y [Department of Applied Chemistry and Institute of Molecular Science, National Chiao Tung University, Hsinchu, 300, Taiwan (China)

    2007-12-15

    We report the techniques for measuring optical properties of a single nanometer-sized diamond. The electron beam (e-beam) lithography defined coordination markers on a silicon wafer provide us a convenient tool for allocating a single nanodiamond immobilized on the surface. By combining a confocal microscope with the e-beam lithography patterned smart substrate, we are able to measure the Raman and photoluminescence spectra from a single nanodiamond with a size less than 100 nm.

  17. Optical properties of a single free standing nanodiamond

    International Nuclear Information System (INIS)

    Sun, K W; Wang, C Y

    2007-01-01

    We report the techniques for measuring optical properties of a single nanometer-sized diamond. The electron beam (e-beam) lithography defined coordination markers on a silicon wafer provide us a convenient tool for allocating a single nanodiamond immobilized on the surface. By combining a confocal microscope with the e-beam lithography patterned smart substrate, we are able to measure the Raman and photoluminescence spectra from a single nanodiamond with a size less than 100 nm

  18. Nonlinear Quantum Optical Springs and Their Nonclassical Properties

    International Nuclear Information System (INIS)

    Faghihi, M.J.; Tavassoly, M.K.

    2011-01-01

    The original idea of quantum optical spring arises from the requirement of quantization of the frequency of oscillations in the Hamiltonian of harmonic oscillator. This purpose is achieved by considering a spring whose constant (and so its frequency) depends on the quantum states of another system. Recently, it is realized that by the assumption of frequency modulation of ω to ω√1+μa † a the mentioned idea can be established. In the present paper, we generalize the approach of quantum optical spring with particular attention to the dependence of frequency to the intensity of radiation field that naturally observes in the nonlinear coherent states, from which we arrive at a physical system has been called by us as nonlinear quantum optical spring. Then, after the introduction of the generalized Hamiltonian of nonlinear quantum optical spring and it's solution, we will investigate the nonclassical properties of the obtained states. Specially, typical collapse and revival in the distribution functions and squeezing parameters, as particular quantum features, will be revealed. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  19. Structure/property relationships in non-linear optical materials

    Energy Technology Data Exchange (ETDEWEB)

    Cole, J M [Institut Max von Laue - Paul Langevin (ILL), 38 - Grenoble (France); [Durham Univ. (United Kingdom); Howard, J A.K. [Durham Univ. (United Kingdom); McIntyre, G J [Institut Max von Laue - Paul Langevin (ILL), 38 - Grenoble (France)

    1997-04-01

    The application of neutrons to the study of structure/property relationships in organic non-linear optical materials (NLOs) is described. In particular, charge-transfer effects and intermolecular interactions are investigated. Charge-transfer effects are studied by charge-density analysis and an example of one such investigation is given. The study of intermolecular interactions concentrates on the effects of hydrogen-bonding and an example is given of two structurally similar molecules with very disparate NLO properties, as a result of different types of hydrogen-bonding. (author). 3 refs.

  20. Investigation of organic liquid-scintillator optical properties

    Energy Technology Data Exchange (ETDEWEB)

    Winter, Juergen; Feilitzsch, Franz von; Goeger-Neff, Marianne; Lewke, Timo; Meindl, Quirin; Oberauer, Lothar; Potzel, Walter; Todor, Sebastian; Wurm, Michael [Physik Department E15, Technische Universitaet Muenchen, James-Franck-Str., 85748 Garching (Germany); Marrodan Undagoitia, Teresa [Physik Department E15, Technische Universitaet Muenchen, James-Franck-Str., 85748 Garching (Germany); Physik-Institut, Universitaet Zuerich (Switzerland)

    2009-07-01

    The characterization of different organic liquid-scintillator mixtures is an important step towards the design of a large-scale detector such as LENA (Low Energy Neutrino Astronomy). Its physics goals, extending from particle and geological to astrophysical issues, set high demands on the optical properties of the liquid scintillator. Therefore, small-scale experiments are carried out in order to optimize the final scintillator mixture. PXE, LAB, and dodecane are under consideration as solvents. Setups for the determination of scintillator properties are presented, such as attenuation length, light yield, emission spectra, fluorescence decay times, and quenching factors. Furthermore, results are discussed.

  1. Enhancing optical response of graphene through stochastic resonance

    Science.gov (United States)

    Ying, Lei; Huang, Liang; Lai, Ying-Cheng

    2018-04-01

    Enhancing the optical response of graphene is a topic of interest with applications in optoelectronics. Subject to light irradiation, graphene can exhibit nontrivial topologically insulating states, effectively turning itself into a Floquet topological insulator due to the time periodicity of the external driving. We find that, when random disorder is present, its interplay with the topologically insulating states can have a dramatic effect on electronic transport through graphene. In particular, we consider the prototypical setting where a graphene nanoribbon is irradiated by circularly polarized light, where the length of the nanoribbon is sufficiently long so that evanescent states have little effect on transport. We uncover a resonance phenomenon in which the conductance is enhanced as the disorder strength is increased from zero, reaches a maximum value for an optimal level of disorder, and decreases as the disorder is strengthened further. With respect to its value at the zero-disorder strength, the maximum conductance value can be as much as 50 % higher. Qualitatively, this can be understood as a result of the dynamical interplay between disorder and Floquet states (channels) generated by light irradiation. Quantitatively, the resonance phenomenon can be explained in the framework of Born theory, where the disorder reorganizes the Floquet Hamiltonian and enhances the effective coupling between the adjacent Floquet conducting channels. That is, disorder is capable of promoting both photon absorption and emission, leading to significant enhancement of nonequilibrium electronic transport. We demonstrate the robustness of the resonance phenomenon by investigating the effects of spatial symmetry breaking on transport and provide an understanding based on analyzing the behavior of the density of states of the Floquet channels.

  2. Influence Al doped ZnO nanostructure on structural and optical properties

    International Nuclear Information System (INIS)

    Ramelan, Ari Handono; Wahyuningsih, Sayekti; Chasanah, Uswatul; Munawaroh, Hanik

    2016-01-01

    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 cause 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.

  3. Optics

    CERN Document Server

    Mathieu, Jean Paul

    1975-01-01

    Optics, Parts 1 and 2 covers electromagnetic optics and quantum optics. The first part of the book examines the various of the important properties common to all electromagnetic radiation. This part also studies electromagnetic waves; electromagnetic optics of transparent isotropic and anisotropic media; diffraction; and two-wave and multi-wave interference. The polarization states of light, the velocity of light, and the special theory of relativity are also examined in this part. The second part is devoted to quantum optics, specifically discussing the classical molecular theory of optical p

  4. THz - ToF Optical Layer Analysis (OLA) to determine optical properties of dielectric materials

    Science.gov (United States)

    Spranger, Holger; Beckmann, Jörg

    2017-02-01

    Electromagnetic waves with frequencies between 0.1 and 10 THz are described as THz-radiation (T-ray). The ability to penetrate dielectric materials makes T-rays attractive to reveal discontinuities in polymer and ceramic materials. THz-Time Domain Spectroscopy Systems (THz-TDS) are available on the market today which operates with THz-pulses transmitted and received by optically pumped semiconductor antennas. In THz-TDS the travelling time (ToF) and shape of the pulse is changed if it interacts with the dielectric material and its inherent discontinuities. A tomogram of the object under the test can be reconstructed from time of flight diffraction (ToFD) scans if a synthetic focusing aperture (SAFT) algorithm is applied. The knowledge of the base materials shape and optical properties is essential for a proper reconstruction result. To obtain these properties a model is assumed which describes the device under the test as multilayer structure composed of thin layers with different dielectric characteristics. The Optical Layer Analysis (OLA) is able to fulfill these requirements. A short description why the optical properties are crucial for meaningful SAFT reconstruction results will be given first. Afterwards the OLA will be derived and applied on representative samples to discuss and evaluate its benefits and limits.

  5. Optical Properties of ZnO Nanoparticles Capped with Polymers

    Directory of Open Access Journals (Sweden)

    Atsushi Noguchi

    2011-06-01

    Full Text Available Optical properties of ZnO nanoparticles capped with polymers were investigated. Polyethylene glycol (PEG and polyvinyl pyrrolidone (PVP were used as capping reagents. ZnO nanoparticles were synthesized by the sol-gel method. Fluorescence and absorption spectra were measured. When we varied the timing of the addition of the polymer to the ZnO nanoparticle solution, the optical properties were drastically changed. When PEG was added to the solution before the synthesis of ZnO nanoparticles, the fluorescence intensity increased. At the same time, the total particle size increased, which indicated that PEG molecules had capped the ZnO nanoparticles. The capping led to surface passivation, which increased fluorescence intensity. However, when PEG was added to the solution after the synthesis of ZnO nanoparticles, the fluorescence and particle size did not change. When PVP was added to the solution before the synthesis of ZnO nanoparticles, aggregation of nanoparticles occurred. When PVP was added to the solution after the synthesis of ZnO nanoparticles, fluorescence and particle size increased. This improvement of optical properties is advantageous to the practical usage of ZnO nanoparticles, such as bioimaging

  6. Electronic and optical properties of diamond/organic semiconductor heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Gajewski, Wojciech; Garrido, Jose; Niedermeier, Martin; Stutzmann, Martin [Walter Schottky Institute, TU Muenchen, Am Coulombwall 3, 85748 Garching (Germany); Williams, Oliver; Haenen, Ken [Institute for Materials Research, University of Hasselt, Wetenschapspark 1, BE-3590 Diepenbeek (Belgium)

    2007-07-01

    Different diamond substrates (single crystalline: SCD, poly-crystalline: PCD and nano-crystalline: NCD) were used to investigate the electronic and optical properties of the diamond/organic semiconductor heterostructures. Layers of a poly[ethynyl-(2-decyloxy-5methoxy)benzene] - PEB, pentacene and 4-nitro-biphenyl-4-diazonium cations - Ph-Ph-NO{sub 2} were prepared by spin coating, thermal evaporation and grafting, respectively. The measurements of the electronic transport along the organic layer were performed using a Hg probe as well as Hall effect measurements in the temperature range 70-400 K. The I-V characteristics of the B-doped diamond/organic semiconductor heterostructures were measured at room temperature by means of the Hg probe. Undoped IIa and undoped PCD films were used for a study of the optical and optoelectronic properties of prepared heterostructures. The influence of the organic layer homogeneity and layer thickness on the optical properties will be discussed. Furthermore, preliminary data on perpendicular and parallel transport in the heterostructures layer will be reported.

  7. Thermo-optical properties of residential coals and combustion aerosols

    Science.gov (United States)

    Pintér, Máté; Ajtai, Tibor; Kiss-Albert, Gergely; Kiss, Diána; Utry, Noémi; Janovszky, Patrik; Palásti, Dávid; Smausz, Tomi; Kohut, Attila; Hopp, Béla; Galbács, Gábor; Kukovecz, Ákos; Kónya, Zoltán; Szabó, Gábor; Bozóki, Zoltán

    2018-04-01

    In this study, we present the inherent optical properties of carbonaceous aerosols generated from various coals (hard through bituminous to lignite) and their correlation with the thermochemical and energetic properties of the bulk coal samples. The nanoablation method provided a unique opportunity for the comprehensive investigation of the generated particles under well controlled laboratory circumstances. First, the wavelength dependent radiative features (optical absorption and scattering) and the size distribution (SD) of the generated particulate matter were measured in-situ in aerosol phase using in-house developed and customised state-of-the-art instrumentation. We also investigated the morphology and microstructure of the generated particles using Transmission Electron Microscopy (TEM) and Electron Diffraction (ED). The absorption spectra of the measured samples (quantified by Absorption Angström Exponent (AAE)) were observed to be distinctive. The correlation between the thermochemical features of bulk coal samples (fixed carbon (FC) to volatile matter (VM) ratio and calorific value (CV)) and the AAE of aerosol assembly were found to be (r2 = 0.97 and r2 = 0.97) respectively. Lignite was off the fitted curves in both cases most probably due to its high optically inactive volatile material content. Although more samples are necessary to be investigated to draw statistically relevant conclusion, the revealed correlation between CV and Single Scattering Albedo (SSA) implies that climatic impact of coal combusted aerosol could depend on the thermal and energetic properties of the bulk material.

  8. Measurement of optical properties of nano-cement using THz electromagnetic waves

    International Nuclear Information System (INIS)

    Kim, Heon Young; Kang, Dong Hoon; Joo, Chulmin; Oh, Seung Jae

    2016-01-01

    Enhancing mechanical strength of concrete has been fascinated using carbon-based nanomaterials such as CNT and graphene. The key to improving strength is a dispersion of nanomaterials. A novel method is required to investigate the dispersion inner concrete nondestructively. In this study, the optical optical properties such as refractive index and absorption coefficient are measured in nano-cement mortar specimens containing MWCNT and GO using THz electro-magnetic waves. From the results, the properties of nano-cement mortar are confirmed to be 1.0% to 2.5% higher in refractive index, and -14% to 28% higher in absorption coefficient than those of cement mortar at the average values. Using these characteristics, visualizing the dispersion of nano-concrete structures seems possible in future

  9. Influence of La Doping on Magnetic and Optical Properties of Bismuth Ferrite Nanofibers

    Directory of Open Access Journals (Sweden)

    Ziang Zhang

    2012-01-01

    Full Text Available The influence of La doping on the crystal structure, ferromagnetic, and optical properties of BFO nanofibers was investigated. Bi1−xLaxFeO3 ultrafine nanofibers were synthesized by the electrospinning method. The surface morphology and crystal structure of the as-spun and sintered fibers were not affected by the doping. The impurity phases of the BFO crystals were weakened with the increment of La concentration. The magnetization field curves showed that the magnetization weakened under low La doping proportion, but strengthened with the increase of the doped proportion. The magnetization curves also showed continuous strong enhancement of ferromagnetic behavior. The results of UV-vis and photoabsorption testing revealed little influence of La doping on the optical property.

  10. CdTe Quantum Dots Embedded in Multidentate Biopolymer Based on Salep: Characterization and Optical Properties

    Directory of Open Access Journals (Sweden)

    Ghasem Rezanejade Bardajee

    2013-01-01

    Full Text Available This paper describes a novel method for surface modification of water soluble CdTe quantum dots (QDs by using poly(acrylic acid grafted onto salep (salep-g-PAA as a biopolymer. As-prepared CdTe-salep-g-PAA QDs were characterized by Fourier transform infrared (FT-IR spectrum, thermogravimetric (TG analysis, and transmission electron microscopy (TEM. The absorption and fluorescence emission spectra were measured to investigate the effect of salep-g-PAA biopolymer on the optical properties of CdTe QDs. The results showed that the optical properties of CdTe QDs were significantly enhanced by using salep-g-PAA-based biopolymer.

  11. Enhancement of magneto-optical Faraday effects and extraordinary optical transmission in a tri-layer structure with rectangular annular arrays.

    Science.gov (United States)

    Lei, Chengxin; Chen, Leyi; Tang, Zhixiong; Li, Daoyong; Cheng, Zhenzhi; Tang, Shaolong; Du, Youwei

    2016-02-15

    The properties of optics and magneto-optical Faraday effects in a metal-dielectric tri-layer structure with subwavelength rectangular annular arrays are investigated. It is noteworthy that we obtained the strongly enhanced Faraday rotation of the desired sign along with high transmittance by optimizing the parameters of the nanostructure in the visible spectral ranges. In this system, we obtained two extraordinary optical transmission (EOT) resonant peaks with enhanced Faraday rotations, whose signs are opposite, which may provide the possibility of designing multi-channel magneto-optical devices. Study results show that the maximum of the figure of merit (FOM) of the structure can be obtained between two EOT resonant peaks accompanied by an enhanced Faraday rotation. The positions of the maximum value of the FOM and resonant peaks of transmission along with a large Faraday rotation can be tailored by simply adjusting the geometric parameters of our models. These research findings are of great importance for future applications of magneto-optical devices.

  12. Enhancing Optical Forces in InP-Based Waveguides.

    Science.gov (United States)

    Aryaee Panah, Mohammad Esmail; Semenova, Elizaveta S; Lavrinenko, Andrei V

    2017-06-08

    Cantilever sensors are among the most important microelectromechanical systems (MEMS), which are usually actuated by electrostatic forces or piezoelectric elements. Although well-developed microfabrication technology has made silicon the prevailing material for MEMS, unique properties of other materials are overlooked in this context. Here we investigate optically induced forces exerted upon a semi-insulating InP waveguide suspended above a highly doped InP:Si substrate, in three different regimes: the epsilon-near-zero (ENZ), with excitation of surface plasmon polaritons (SPPs) and phonons excitation. An order of magnitude amplification of the force is observed when light is coupled to SPPs, and three orders of magnitude amplification is achieved in the phonon excitation regime. In the ENZ regime, the force is found to be repulsive and higher than that in a waveguide suspended above a dielectric substrate. Low losses in InP:Si result in a big propagation length. The induced deflection can be detected by measuring the phase change of the light when passing through the waveguide, which enables all-optical functioning, and paves the way towards integration and miniaturization of micro-cantilevers. In addition, tunability of the ENZ and the SPP excitation wavelength ranges, via adjusting the carrier concentration, provides an extra degree of freedom for designing MEMS devices.

  13. Enhancing Optical Forces in InP-Based Waveguides

    DEFF Research Database (Denmark)

    Panah, Mohammad Esmail Aryaee; Semenova, Elizaveta; Lavrinenko, Andrei

    2017-01-01

    Cantilever sensors are among the most important microelectromechanical systems (MEMS), which are usually actuated by electrostatic forces or piezoelectric elements. Although well-developed microfabrication technology has made silicon the prevailing material for MEMS, unique properties of other...... materials are overlooked in this context. Here we investigate optically induced forces exerted upon a semi-insulating InP waveguide suspended above a highly doped InP: Si substrate, in three different regimes: the epsilon-near-zero (ENZ), with excitation of surface plasmon polaritons (SPPs) and phonons...... excitation. An order of magnitude amplification of the force is observed when light is coupled to SPPs, and three orders of magnitude amplification is achieved in the phonon excitation regime. In the ENZ regime, the force is found to be repulsive and higher than that in a waveguide suspended above...

  14. Noise-Immune Cavity-Enhanced Optical Frequency Comb Spectroscopy

    Science.gov (United States)

    Rutkowski, Lucile; Khodabakhsh, Amir; Johanssson, Alexandra C.; Foltynowicz, Aleksandra

    2015-06-01

    We present noise-immune cavity-enhanced optical frequency comb spectroscopy (NICE-OFCS), a recently developed technique for sensitive, broadband, and high resolution spectroscopy. In NICE-OFCS an optical frequency comb (OFC) is locked to a high finesse cavity and phase-modulated at a frequency precisely equal to (a multiple of) the cavity free spectral range. Since each comb line and sideband is transmitted through a separate cavity mode in exactly the same way, any residual frequency noise on the OFC relative to the cavity affects each component in an identical manner. The transmitted intensity contains a beat signal at the modulation frequency that is immune to frequency-to-amplitude noise conversion by the cavity, in a way similar to continuous wave noise-immune cavity-enhanced optical heterodyne molecular spectroscopy (NICE-OHMS). The light transmitted through the cavity is detected with a fast-scanning Fourier-transform spectrometer (FTS) and the NICE-OFCS signal is obtained by fast Fourier transform of the synchronously demodulated interferogram. Our NICE-OFCS system is based on an Er:fiber femtosecond laser locked to a cavity with a finesse of ˜9000 and a fast-scanning FTS equipped with a high-bandwidth commercial detector. We measured NICE-OFCS signals from the 3νb{1}+νb{3} overtone band of CO_2 around 1.57 μm and achieved absorption sensitivity 6.4×10-11cm-1 Hz-1/2 per spectral element, corresponding to a minimum detectable CO_2 concentration of 25 ppb after 330 s integration time. We will describe the principles of the technique and its technical implementation, and discuss the spectral lineshapes of the NICE-OFCS signals. A. Khodabakhsh, C. Abd Alrahman, and A. Foltynowicz, Opt. Lett. 39, 5034-5037 (2014). J. Ye, L. S. Ma, and J. L. Hall, J. Opt. Soc. Am. B 15, 6-15 (1998). A. Khodabakhsh, A. C. Johansson, and A. Foltynowicz, Appl. Phys. B (2015) doi:10.1007/s00340-015-6010-7.

  15. Superfocusing properties of disorder-enhanced plasmonic nanolenses

    KAUST Repository

    Gongora, J. S. Totero; Coluccio, Maria Laura; Proietti Zaccaria, Remo; Di Fabrizio, Enzo M.; Fratalocchi, Andrea

    2014-01-01

    We investigated a disordered plasmonic nanolens using an extensive campaign of FDTD simulations. Our results show that surface roughness plays a crucial role in the enhancement of the electromagnetic energy with respect to regular structures. © 2014 Optical Society of America.

  16. Silver nanoparticles as optical clearing agent enhancers to improve caries diagnostic by optical coherence tomography

    Science.gov (United States)

    Carneiro, Vanda S. M.; Mota, Cláudia C. B. O.; Souza, Alex F.; da Silva, Evair J.; da Silva, Andrea F.; Gerbi, Marleny E. M. M.; Gomes, Anderson S. L.

    2018-02-01

    The use of silver nanoparticles as optical clearing agent (OCA) enhancers to improve caries diagnostic by optical coherence tomography (OCT) is demonstrated here. Five molars with no evident cavitation were selected. The OCAs were based on aqueous solution of silver nanoparticles (AgNP, 1.18x 1014 particles/mL, ø ≈ 10nm) and its dilution at 10% in glycerol. Teeth were placed on a platform with a micrometric screw, and after applying the OCAs, they were scanned with a Callisto SD-OCT system operating ate 930nm central wavelength. The occlusal surfaces were scanned by OCT, capturing crosssectional images with 8 mm transversal scanning, generating numerical matrices (2000x512). The OCT images had their transverse dimension preserved. AgNP-OCAs promoted image stretching due to the modification in the light optical path caused by AgNP-OCAs refractive indices close to that of the enamel. AgNP-OCAs evidenced the enamel birefringence and highlighted initial demineralization areas, that presented defined margins with higher contrast between sound and demineralized regions, with higher OCT signal intensity in those areas.

  17. Surface-enhanced raman optical data storage system

    Science.gov (United States)

    Vo-Dinh, Tuan

    1994-01-01

    An improved Surface-Enhanced Raman Optical Data Storage System (SERODS) is disclosed. In the improved system, entities capable of existing in multiple reversible states are present on the storage device. Such entities result in changed Surface-Enhanced Raman Scattering (SERS) when localized state changes are effected in less than all of the entities. Therefore, by changing the state of entities in localized regions of a storage device, the SERS emissions in such regions will be changed. When a write-on device is controlled by a data signal, such a localized regions of changed SERS emissions will correspond to the data written on the device. The data may be read by illuminating the surface of the storage device with electromagnetic radiation of an appropriate frequency and detecting the corresponding SERS emissions. Data may be deleted by reversing the state changes of entities in regions where the data was initially written. In application, entities may be individual molecules which allows for the writing of data at the molecular level. A read/write/delete head utilizing near-field quantum techniques can provide for a write/read/delete device capable of effecting state changes in individual molecules, thus providing for the effective storage of data at the molecular level.

  18. Coherence enhanced quantum metrology in a nonequilibrium optical molecule

    Science.gov (United States)

    Wang, Zhihai; Wu, Wei; Cui, Guodong; Wang, Jin

    2018-03-01

    We explore the quantum metrology in an optical molecular system coupled to two environments with different temperatures, using a quantum master equation beyond secular approximation. We discover that the steady-state coherence originating from and sustained by the nonequilibrium condition can enhance quantum metrology. We also study the quantitative measures of the nonequilibrium condition in terms of the curl flux, heat current and entropy production at the steady state. They are found to grow with temperature difference. However, an apparent paradox arises considering the contrary behaviors of the steady-state coherence and the nonequilibrium measures in relation to the inter-cavity coupling strength. This paradox is resolved by decomposing the heat current into a population part and a coherence part. Only the latter, the coherence part of the heat current, is tightly connected to the steady-state coherence and behaves similarly with respect to the inter-cavity coupling strength. Interestingly, the coherence part of the heat current flows from the low-temperature reservoir to the high-temperature reservoir, opposite to the direction of the population heat current. Our work offers a viable way to enhance quantum metrology for open quantum systems through steady-state coherence sustained by the nonequilibrium condition, which can be controlled and manipulated to maximize its utility. The potential applications go beyond quantum metrology and extend to areas such as device designing, quantum computation and quantum technology in general.

  19. Quantitative evaluation of enhanced laser tattoo removal by skin optical clearing

    Directory of Open Access Journals (Sweden)

    Caihua Liu

    2015-05-01

    Full Text Available Lasers have been widely used for tattoo removal, but the limited light penetration depth caused by high skin scattering property restricts the therapeutic outcome of deep tattoo. Skin optical clearing method, by introducing optical clearing agent (OCA into skin, has shown some improvement in the effect of laser tattoo removal. In this study, the enhanced laser tattoo removal has been quantitatively assessed. OCA was applied to the skin of tattoo animal model and Q-switched Nd:YAG laser (1064 nm irradiation was used to remove the tattoo. The skin evaluation instrument (Mexameter probe, MPA580 was applied to measure the content of tattoo pigment before and after laser treatment, and then the clearance rate of pigment was calculated. Further, Monte Carlo (MC method was utilized to simulate the effect of skin optical clearing on light transmission in tattoo skin model. By comparing the pigment change of tattoo areas respectively treated with OCA plus laser and single laser, it was found that pigment clearance of the former tattoo area was increased by 1.5-fold. Further, the MC simulation verified that the reduced light scattering in skin could increase the effective dose of luminous flux reaching to the deep tattoo regions. It can be concluded from both experiment and theoretical simulations that skin optical clearing technique could improve the outcome of laser tattoo removal, which should be beneficial for clinical laser tattoo removal and other laser pigment elimination.

  20. Optical Properties of Plasmon Resonances with Ag/SiO2/Ag Multi-Layer Composite Nanoparticles

    International Nuclear Information System (INIS)

    Ye-Wan, Ma; Li-Hua, Zhang; Zhao-Wang, Wu; Jie, Zhang

    2010-01-01

    Optical properties of plasmon resonance with Ag/SiO 2 /Ag multi-layer nanoparticles are studied by numerical simulation based on Green's function theory. The results show that compared with single-layer Ag nanoparticles, the multi-layer nanoparticles exhibit several distinctive optical properties, e.g. with increasing the numbers of the multi-layer nanoparticles, the scattering efficiency red shifts, and the intensity of scattering enhances accordingly. It is interesting to find out that slicing an Ag-layer into multi-layers leads to stronger scattering intensity and more 'hot spots' or regions of stronger field enhancement. This property of plasmon resonance of surface Raman scattering has greatly broadened the application scope of Raman spectroscopy. The study of metal surface plasmon resonance characteristics is critical to the further understanding of surface enhanced Raman scattering as well as its applications. (fundamental areas of phenomenology (including applications))

  1. Design and investigation of properties of nanocrystalline diamond optical planar waveguides.

    Science.gov (United States)

    Prajzler, Vaclav; Varga, Marian; Nekvindova, Pavla; Remes, Zdenek; Kromka, Alexander

    2013-04-08

    Diamond thin films have remarkable properties comparable with natural diamond. Because of these properties it is a very promising material for many various applications (sensors, heat sink, optical mirrors, chemical and radiation wear, cold cathodes, tissue engineering, etc.) In this paper we report about design, deposition and measurement of properties of optical planar waveguides fabricated from nanocrystalline diamond thin films. The nanocrystalline diamond planar waveguide was deposited by microwave plasma enhanced chemical vapor deposition and the structure of the deposited film was studied by scanning electron microscopy and Raman spectroscopy. The design of the presented planar waveguides was realized on the bases of modified dispersion equation and was schemed for 632.8 nm, 964 nm, 1 310 nm and 1 550 nm wavelengths. Waveguiding properties were examined by prism coupling technique and it was found that the diamond based planar optical element guided one fundamental mode for all measured wavelengths. Values of the refractive indices of our NCD thin film measured at various wavelengths were almost the same as those of natural diamond.

  2. Thermo- and electro-optical properties of photonic liquid crystal fibers doped with gold nanoparticles

    Directory of Open Access Journals (Sweden)

    Agata Siarkowska

    2017-12-01

    Full Text Available Thermo- and electro-optical properties of a photonic liquid crystal fiber (PLCF enhanced by the use of dopants have been investigated. A 6CHBT nematic liquid crystal was doped with four different concentrations of gold nanoparticles (NPs, 0.1, 0.3, 0.5 and 1.0 wt %, for direct comparison of the influence of the dopant on the properties of the PLCF. The thermo-optical effects of the liquid crystal doped with gold NPs were compared in three setups, an LC cell, a microcapillary and within the PLCF, to determine if the observed responses to external factors are caused by the properties of the infiltration material or due to the setup configuration. The results obtained indicated that with increasing NP doping a significant reduction of the rise time under an external electric field occurs with a simultaneous decrease in the nematic–isotropic phase transition temperature, thus improving the thermo- and electro-optical properties of the PLCF.

  3. Thermo- and electro-optical properties of photonic liquid crystal fibers doped with gold nanoparticles.

    Science.gov (United States)

    Siarkowska, Agata; Chychłowski, Miłosz; Budaszewski, Daniel; Jankiewicz, Bartłomiej; Bartosewicz, Bartosz; Woliński, Tomasz R

    2017-01-01

    Thermo- and electro-optical properties of a photonic liquid crystal fiber (PLCF) enhanced by the use of dopants have been investigated. A 6CHBT nematic liquid crystal was doped with four different concentrations of gold nanoparticles (NPs), 0.1, 0.3, 0.5 and 1.0 wt %, for direct comparison of the influence of the dopant on the properties of the PLCF. The thermo-optical effects of the liquid crystal doped with gold NPs were compared in three setups, an LC cell, a microcapillary and within the PLCF, to determine if the observed responses to external factors are caused by the properties of the infiltration material or due to the setup configuration. The results obtained indicated that with increasing NP doping a significant reduction of the rise time under an external electric field occurs with a simultaneous decrease in the nematic-isotropic phase transition temperature, thus improving the thermo- and electro-optical properties of the PLCF.

  4. Optical and optoelectronic properties of nanostructures based on wide-bandgap semiconductors

    International Nuclear Information System (INIS)

    Kalden, Joachim

    2010-01-01

    Recently, more and more research is done on nitride nanostructures in order to control the electrical and optical properties in a more sophisticated manner for optimized light-matter-interaction and extraction efficiency. In this context, the work presented in this thesis has been carried out, concentrating on two main topics. One aspect is the characterization of InGaN quantum dots (QDs). QDs possess a unique atom-like density of states for electrons, allowing for generation and manipulation of discrete electronic states. This thesis contains the analysis of QDs embedded in optoelectronic devices such as LEDs. Measurements of the electroluminescence (EL) of QD ensembles as well as single QDs are presented. Especially QD EL obtained at higher temperatures up to 150 K is a main achievement of this work. Furthermore, the photoluminescence (PL) of QD multilayer structures has been examined and discussed in detail. Experiments on the optical amplification in these multilayers have been carried out for the first time, yielding a maximum optical gain of g(max)/(mod)=50/cm. Another main aspect of solid state lighting is the efficient light extraction from light sources. For this purpose, pillar microcavities based on nitrides have been investigated. This type of optical resonator possesses a discrete optical mode structure due to the three-dimensional optical confinement in these structures. For optimal light-matter coupling conditions, this leads to an enhanced extraction efficiency. In this context, studies on QD pillar microcavities (MCs) processed by focused ion beam milling from planar MC structures are presented. After a detailed analysis of the photonic properties of these pillar MCs, a temperature-variation method to tune the cavity in resonance with QD emission is demonstrated, yielding a five-fold enhancement of the extraction efficiency. These experiments were carried out on selenide-based structures which possess a very high structural quality. An alternative

  5. Aerosol Optical Properties in Southeast Asia From AERONET Observations

    Science.gov (United States)

    Eck, T. F.; Holben, B. N.; Boonjawat, J.; Le, H. V.; Schafer, J. S.; Reid, J. S.; Dubovik, O.; Smirnov, A.

    2003-12-01

    There is little published data available on measured optical properties of aerosols in the Southeast Asian region. The AERONET project and collaborators commenced monitoring of aerosol optical properties in February 2003 at four sites in Thailand and two sites in Viet Nam to measure the primarily anthropogenic aerosols generated by biomass burning and fossil fuel combustion/ industrial emissions. Automatic sun/sky radiometers at each site measured spectral aerosol optical depth in 7 wavelengths from 340 to 1020 nm and combined with directional radiances in the almucantar, retrievals were made of spectral single scattering albedo and aerosol size distributions. Angstrom exponents, size distributions and spectral single scattering albedo of primarily biomass burning aerosols at rural sites are compared to measurements made at AERONET sites in other major biomass burning regions in tropical southern Africa, South America, and in boreal forest regions. Additionally, the aerosol single scattering albedo and size distributions measured in Bangkok, Thailand are compared with those measured at other urban sites globally. The influences of aerosols originating from other regions outside of Southeast Asia are analyzed using trajectory analyses. Specifically, cases of aerosol transport and mixing from Southern China and from India are presented.

  6. X-ray, optical, and radio properties of quasars

    International Nuclear Information System (INIS)

    Blumenthal, G.R.; Keel, W.C.; Miller, J.S.

    1982-01-01

    We have examined a sample of 26 low-redshift quasars for the relationships between X-ray luminosity and optical spectroscopic features. All quasars were observed with the Einstein Observatory and with the IDS on the Lick 3 meter telescope. We find evidence for correlations between quasar X-ray luminosity and both optical continuum luminosity and Hβ luminosity. In the latter case, there is a smooth relationship connecting quasars, Seyfert 1, and Seyfert 2 galaxies. For the quasars in this sample, there is also a strong correlation between optical continuum luminosity and both the Hβ luminosity and equivalent width. Unlike the case for Seyfert 1 nuclei, there is no evidence for a correlation between X-ray luminosity and either the Hβ/[O III] ratio or the width at zero intensity of the Hβ line. However, we do find some evidence for a weak correlation between α'/sub o/x, the mean continuum spectral index between 5000 A and 2 keV, and Fe II equivalent width, Hβ equivalent width, Hβ line width at zero intensity, and the ratio of Hβ equivalent width to its line width at zero intensity. Overall, we found few strong correlations between optical spectroscopic quanitites and X-ray properties of quasars. Some of the implications of these results for models of quasars and quasar emission line regions are discussed

  7. Optical properties of gold films and the Casimir force

    International Nuclear Information System (INIS)

    Svetovoy, V. B.; Zwol, P. J. van; Palasantzas, G.; De Hosson, J. Th. M.

    2008-01-01

    Precise optical properties of metals are very important for accurate prediction of the Casimir force acting between two metallic plates. Therefore we measured ellipsometrically the optical responses of Au films in a wide range of wavelengths from 0.14 to 33 μm. The films at various thicknesses were deposited at different conditions on silicon or mica substrates. Considerable variation of the frequency dependent dielectric function from sample to sample was found. Detailed analysis of the dielectric functions was performed to check the Kramers-Kronig consistency, and extract the Drude parameters of the films. It was found that the plasma frequency varies in the range from 6.8 to 8.4 eV. It is suggested that this variation is related with the film density. X-ray reflectivity measurements support qualitatively this conclusion. The Casimir force is evaluated for the dielectric functions corresponding to our samples, and for that typically used in the precise prediction of the force. The force for our films was found to be 5%-14% smaller at a distance of 100 nm between the plates. Noise in the optical data is responsible for the force variation within 1%. It is concluded that prediction of the Casimir force between metals with a precision better than 10% must be based on the material optical response measured from visible to mid-infrared range

  8. Optical re-injection in cavity-enhanced absorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Leen, J. Brian, E-mail: b.leen@lgrinc.com; O’Keefe, Anthony [Los Gatos Research, 67 E. Evelyn Avenue, Suite 3, Mountain View, California 94041 (United States)

    2014-09-15

    Non-mode-matched cavity-enhanced absorption spectrometry (e.g., cavity ringdown spectroscopy and integrated cavity output spectroscopy) is commonly used for the ultrasensitive detection of trace gases. These techniques are attractive for their simplicity and robustness, but their performance may be limited by the reflection of light from the front mirror and the resulting low optical transmission. Although this low transmitted power can sometimes be overcome with higher power lasers and lower noise detectors (e.g., in the near-infrared), many regimes exist where the available light intensity or photodetector sensitivity limits instrument performance (e.g., in the mid-infrared). In this article, we describe a method of repeatedly re-injecting light reflected off the front mirror of the optical cavity to boost the cavity's circulating power and deliver more light to the photodetector and thus increase the signal-to-noise ratio of the absorption measurement. We model and experimentally demonstrate the method's performance using off-axis cavity ringdown spectroscopy (OA-CRDS) with a broadly tunable external cavity quantum cascade laser. The power coupled through the cavity to the detector is increased by a factor of 22.5. The cavity loss is measured with a precision of 2 × 10{sup −10} cm{sup −1}/√(Hz;) an increase of 12 times over the standard off-axis configuration without reinjection and comparable to the best reported sensitivities in the mid-infrared. Finally, the re-injected CRDS system is used to measure the spectrum of several volatile organic compounds, demonstrating the improved ability to resolve weakly absorbing spectroscopic features.

  9. Electronic properties and optical absorption of graphene-polyvinylidene fluoride nanocomposites: A theoretical study

    Energy Technology Data Exchange (ETDEWEB)

    Chopra, Siddheshwar, E-mail: schopra1@amity.edu

    2017-01-15

    Graphene/polyvinylidene fluoride (graphene/PVDF) nanocomposites were studied using Density functional theory (DFT)/Time dependent density functional theory (TDDFT) calculations. Five nanocomposite configurations were constructed. Electronic properties like binding energy, electronic gap and work function were calculated. The most stable structure was determined. The electronic gap of graphene shifts from semiconducting to conducting, on nanocomposite formation. Workfunction of the most stable nanocomposite was 4.34eV ± 0.05eV, close to that of the pristine graphene (4.33eV ± 0.05eV). Thermochemical analysis showed that the adsorption is spontaneous above ∼870 K, and endothermic in nature. TDDFT calculations were performed for B3LYP, LSDA, BHHLYP and PBE0 functionals. B3LYP and PBE0 are suitable in describing optical absorption. Optical gap of graphene shrinks, and light absorption gets enhanced on nanocomposite formation. - Highlights: • Various properties of graphene-PVDF nanocomposites were studied theoretically. • Electronic gap of graphene shifts to conducting nature, on composite formation. • Adsorption is spontaneous above ∼870 K, and endothermic in nature. • B3LYP and PBE0 functionals are suitable in describing absorption. • Optical absorption gets enhanced on nanocomposite formation.

  10. Electronic properties and optical absorption of graphene-polyvinylidene fluoride nanocomposites: A theoretical study

    International Nuclear Information System (INIS)

    Chopra, Siddheshwar

    2017-01-01

    Graphene/polyvinylidene fluoride (graphene/PVDF) nanocomposites were studied using Density functional theory (DFT)/Time dependent density functional theory (TDDFT) calculations. Five nanocomposite configurations were constructed. Electronic properties like binding energy, electronic gap and work function were calculated. The most stable structure was determined. The electronic gap of graphene shifts from semiconducting to conducting, on nanocomposite formation. Workfunction of the most stable nanocomposite was 4.34eV ± 0.05eV, close to that of the pristine graphene (4.33eV ± 0.05eV). Thermochemical analysis showed that the adsorption is spontaneous above ∼870 K, and endothermic in nature. TDDFT calculations were performed for B3LYP, LSDA, BHHLYP and PBE0 functionals. B3LYP and PBE0 are suitable in describing optical absorption. Optical gap of graphene shrinks, and light absorption gets enhanced on nanocomposite formation. - Highlights: • Various properties of graphene-PVDF nanocomposites were studied theoretically. • Electronic gap of graphene shifts to conducting nature, on composite formation. • Adsorption is spontaneous above ∼870 K, and endothermic in nature. • B3LYP and PBE0 functionals are suitable in describing absorption. • Optical absorption gets enhanced on nanocomposite formation.

  11. Optical and luminescence properties of zinc oxide (Review)

    Science.gov (United States)

    Rodnyi, P. A.; Khodyuk, I. V.

    2011-11-01

    We generalize and systematize basic experimental data on optical and luminescence properties of ZnO single crystals, thin films, powders, ceramics, and nanocrystals. We consider and study mechanisms by which two main emission bands occur, a short-wavelength band near the fundamental absorption edge and a broad long-wavelength band, the maximum of which usually lies in the green spectral range. We determine a relationship between the two luminescence bands and study in detail the possibility of controlling the characteristics of ZnO by varying the maximum position of the short-wavelength band. We show that the optical and luminescence characteristics of ZnO largely depend on the choice of the corresponding impurity and the parameters of the synthesis and subsequent treatment of the sample. Prospects for using zinc oxide as a scintillator material are discussed. Additionally, we consider experimental results that are of principal interest for practice.

  12. Optical and physical properties of samarium doped lithium diborate glasses

    Science.gov (United States)

    Hanumantharaju, N.; Sardarpasha, K. R.; Gowda, V. C. Veeranna

    2018-05-01

    Sm3+ doped lithium di-borate glasses with composition 30Li2O-60B2O3-(10-x) PbO, (where 0 molar volume with samarium ion content indicates the openness of the glass structure. The gradual increase in average separation of boron-boron atoms with VmB clearly indicates deterioration of borate glass network, which in turn leads to decrease in the oxygen packing density. The replacements of Sm2O3 for PbO depolymerise the chain structure and that would increase the concentration of non-bridging oxygens. The marginal increase of optical band gap energy after 1.0 mol.% of Sm2O3 is explained by considering the structural modification in lead-borate. The influence of Sm3+ ion on physical and optical properties in lithium-lead-borate glasses is investigated and the results were discussed in view of the structure of borate glass network.

  13. Optical properties of Sulfur doped InP single crystals

    Science.gov (United States)

    El-Nahass, M. M.; Youssef, S. B.; Ali, H. A. M.

    2014-05-01

    Optical properties of InP:S single crystals were investigated using spectrophotometric measurements in the spectral range of 200-2500 nm. The absorption coefficient and refractive index were calculated. It was found that InP:S crystals exhibit allowed and forbidden direct transitions with energy gaps of 1.578 and 1.528 eV, respectively. Analysis of the refractive index in the normal dispersion region was discussed in terms of the single oscillator model. Some optical dispersion parameters namely: the dispersion energy (Ed), single oscillator energy (Eo), high frequency dielectric constant (ɛ∞), and lattice dielectric constant (ɛL) were determined. The volume and the surface energy loss functions (VELF & SELF) were estimated. Also, the real and imaginary parts of the complex conductivity were calculated.

  14. Optical properties of metallic nanoparticles basic principles and simulation

    CERN Document Server

    Trügler, Andreas

    2016-01-01

    This book introduces the fascinating world of plasmonics and physics at the nanoscale, with a focus on simulations and the theoretical aspects of optics and nanotechnology. A research field with numerous applications, plasmonics bridges the gap between the micrometer length scale of light and the secrets of the nanoworld. This is achieved by binding light to charge density oscillations of metallic nanostructures, so-called surface plasmons, which allow electromagnetic radiation to be focussed down to spots as small as a few nanometers. The book is a snapshot of recent and ongoing research and at the same time outlines our present understanding of the optical properties of metallic nanoparticles, ranging from the tunability of plasmonic resonances to the ultrafast dynamics of light-matter interaction. Beginning with a gentle introduction that highlights the basics of plasmonic interactions and plasmon imaging, the author then presents a suitable theoretical framework for the description of metallic nanostructu...

  15. Electronic structure and optical properties of metal doped tetraphenylporphyrins

    Science.gov (United States)

    Shah, Esha V.; Roy, Debesh R.

    2018-05-01

    A density functional scrutiny on the structure, electronic and optical properties of metal doped tetraphenylporphyrins MTPP (M=Fe, Co, Ni) is performed. The structural stability of the molecules is evaluated based on the electronic parameters like HOMO-LUMO gap (HLG), chemical hardness (η) and binding energy of the central metal atom to the molecular frame etc. The computed UltraViolet-Visible (UV-Vis) optical absorption spectra for all the compounds are also compared. The molecular structures reported are the lowest energy configurations. The entire calculations are carried out with a widely reliable functional, viz. B3LYP with a popular basis set which includes a scaler relativistic effect, viz. LANL2DZ.

  16. Climatology of Aerosol Optical Properties in Southern Africa

    Science.gov (United States)

    Queface, Antonio J.; Piketh, Stuart J.; Eck, Thomas F.; Tsay, Si-Chee

    2011-01-01

    A thorough regionally dependent understanding of optical properties of aerosols and their spatial and temporal distribution is required before we can accurately evaluate aerosol effects in the climate system. Long term measurements of aerosol optical depth, Angstrom exponent and retrieved single scattering albedo and size distribution, were analyzed and compiled into an aerosol optical properties climatology for southern Africa. Monitoring of aerosol parameters have been made by the AERONET program since the middle of the last decade in southern Africa. This valuable information provided an opportunity for understanding how aerosols of different types influence the regional radiation budget. Two long term sites, Mongu in Zambia and Skukuza in South Africa formed the core sources of data in this study. Results show that seasonal variation of aerosol optical thicknesses at 500 nm in southern Africa are characterized by low seasonal multi-month mean values (0.11 to 0.17) from December to May, medium values (0.20 to 0.27) between June and August, and high to very high values (0.30 to 0.46) during September to November. The spatial distribution of aerosol loadings shows that the north has high magnitudes than the south in the biomass burning season and the opposite in none biomass burning season. From the present aerosol data, no long term discernable trends are observable in aerosol concentrations in this region. This study also reveals that biomass burning aerosols contribute the bulk of the aerosol loading in August-October. Therefore if biomass burning could be controlled, southern Africa will experience a significant reduction in total atmospheric aerosol loading. In addition to that, aerosol volume size distribution is characterized by low concentrations in the non biomass burning period and well balanced particle size contributions of both coarse and fine modes. In contrast high concentrations are characteristic of biomass burning period, combined with

  17. Studies on Optical and Electrical Properties of Hafnium Oxide Nanoparticles

    Science.gov (United States)

    Jayaraman, Venkatachalam; Sagadevan, Suresh; Sudhakar, Rajesh

    2017-07-01

    In this paper, the synthesis and physico-chemical properties of hafnium oxide nanoparticles (HfO2 NPs) are analyzed and reported. The synthesis was carried out by the precipitation route by using hafnium tetrachloride (HfCl4) as precursor material with potassium hydroxide (KOH) dissolved in Millipore water. In the precipitation technique, the chemical reaction is comparatively simple, low-cost and non-toxic compared to other synthetic methods. The synthesized HfO2 NPs were characterized by using powder x-ray diffraction (PXRD), ultraviolet-visible (UV-Vis) spectroscopy, Raman analysis, and high-resolution transmission electron microscopy (HRTEM). The monoclinic structure of the HfO2 NPs was resolved utilizing x-ray diffraction (XRD). The optical properties were studied from the UV-Vis absorption spectrum. The optical band gap of the HfO2NPs was observed to be 5.1 eV. The Raman spectrum shows the presence of HfO2 NPs. The HRTEM image showed that the HfO2 NPs were of spherical shape with an average particle size of around 28 nm. The energy-dispersive x-ray spectroscopy (EDS) spectrum obviously demonstrated the presence of HfO2 NPs. Analysis and studies on the dielectric properties of the HfO2 NPs such as the dielectric constant, the dielectric loss, and alternating current (AC) conductivity were carried out at varying frequencies and temperatures.

  18. Composite Materials with Magnetically Aligned Carbon Nanoparticles Having Enhanced Electrical Properties and Methods of Preparation

    Science.gov (United States)

    Hong, Haiping (Inventor); Peterson, G.P. (Bud) (Inventor); Salem, David R. (Inventor)

    2016-01-01

    Magnetically aligned carbon nanoparticle composites have enhanced electrical properties. The composites comprise carbon nanoparticles, a host material, magnetically sensitive nanoparticles and a surfactant. In addition to enhanced electrical properties, the composites can have enhanced mechanical and thermal properties.

  19. Electrochemical synthesis of mesoporous gold films toward mesospace-stimulated optical properties

    Science.gov (United States)

    Li, Cuiling; Dag, Ömer; Dao, Thang Duy; Nagao, Tadaaki; Sakamoto, Yasuhiro; Kimura, Tatsuo; Terasaki, Osamu; Yamauchi, Yusuke

    2015-03-01

    Mesoporous gold (Au) films with tunable pores are expected to provide fascinating optical properties stimulated by the mesospaces, but they have not been realized yet because of the difficulty of controlling the Au crystal growth. Here, we report a reliable soft-templating method to fabricate mesoporous Au films using stable micelles of diblock copolymers, with electrochemical deposition advantageous for precise control of Au crystal growth. Strong field enhancement takes place around the center of the uniform mesopores as well as on the walls between the pores, leading to the enhanced light scattering as well as surface-enhanced Raman scattering (SERS), which is understandable, for example, from Babinet principles applied for the reverse system of nanoparticle ensembles.

  20. Investigation on the structural and nonlinear optical properties of Pt doped TiO2 nanoparticles

    International Nuclear Information System (INIS)

    Rahulan, K. Mani; Padmanathan, N.; Vinitha, G.; Kanakam, Charles Christopher

    2013-01-01

    Graphical abstract: The open aperture Z-scan traces of Pt doped TiO 2 nanoparticles at different Pt concentrations were carried out at an irradiation wavelength of 532 nm. It was numerically found that, two photon absorption (TPA) type process gives the best fit to the obtained open aperture Z-scan data. The nonlinear transmission was found to be of third order as it fits to a two-photon absorption. The optical limiting performances of nanoparticles were greatly enhanced with increased volume ratio of Pt. Increasing particle size reduced the limiting threshold and enhanced the optical limiting performance. - Highlights: • Pt doped TiO 2 nanoparticles with different concentrations of Pt have been synthesized by sol–gel method. • The average fluorescence lifetime decreases as the volume fraction of Pt dopant increases. • The effects of Pt content on the optical limiting property were investigated by open aperture Z-scan measurements done at 532 nm using 5 ns laser pulses. • The values of the third-order nonlinearities of nanoparticles are interesting from the application point of view which could be used as a potential candidate for the application of nonlinear optical device. - Abstract: Pt doped TiO 2 nanoparticles with different concentrations of Pt were prepared by sol–gel method. X-ray diffraction (XRD) study reveals that the samples have a homogeneous anatase phase tetragonal system and the lattice parameter analysis indicates that Pt ions substitute into the lattice of TiO 2 . The addition of dopant increases the growth of TiO 2 grains, agglomerates them and shifts the absorption band of TiO 2 from ultraviolet to visible region. The incorporation of Pt in TiO 2 is also confirmed by fluorescence quenching and the fluorescence lifetime decreases as the volume fraction of Pt dopant increases. Open aperture Z-scan measurements done at 532 nm using 7 ns laser pulses show nonlinear absorption which arises from an effective two photon absorption process

  1. Characterization of thin TiO2 films prepared by plasma enhanced chemical vapour deposition for optical and photocatalytic applications

    International Nuclear Information System (INIS)

    Sobczyk-Guzenda, A.; Gazicki-Lipman, M.; Szymanowski, H.; Kowalski, J.; Wojciechowski, P.; Halamus, T.; Tracz, A.

    2009-01-01

    Thin titanium oxide films were deposited using a radio frequency (RF) plasma enhanced chemical vapour deposition method. Their optical properties and thickness were determined by means of ultraviolet-visible absorption spectrophotometry. Films of the optical parameters very close to those of titanium dioxide have been obtained at the high RF power input. Their optical quality is high enough to allow for their use in a construction of stack interference optical filters. At the same time, these materials exhibit strong photocatalytic effects. The results of structural analysis, carried out by Raman Shift Spectroscopy, show that the coatings posses amorphous structure. However, Raman spectra of the same films subjected to thermal annealing at 450 o C disclose an appearance of a crystalline form, namely that of anatase. Surface morphology of the films has also been characterized by Atomic Force Microscopy revealing granular, broccoli-like topography of the films.

  2. Optical and thermal properties in ultrafast laser surface nanostructuring on biodegradable polymer

    Science.gov (United States)

    Yada, Shuhei; Terakawa, Mitsuhiro

    2015-03-01

    We investigate the effect of optical and thermal properties in laser-induced periodic surface structures (LIPSS) formation on a poly-L-lactic acid (PLLA), a biodegradable polymer. Surface properties of biomaterials are known to be one of the key factors in tissue engineering. Methods to process biomaterial surfaces have been studied widely to enhance cell adhesive and anisotropic properties. LIPSS formation has advantages in a dry processing which is able to process complex-shaped surfaces without using a toxic chemical component. LIPSS, however, was difficult to be formed on PLLA due to its thermal and optical properties compared to other polymers. To obtain new perspectives in effect of these properties above, LIPSS formation dependences on wavelength, pulse duration and repetition rate have been studied. At 800 nm of incident wavelength, high-spatial frequency LIPSS (HSFL) was formed after applying 10000 femtosecond pulses at 1.0 J/cm2 in laser fluence. At 400 nm of the wavelength, HSFL was formed at fluences higher than 0.20 J/cm2 with more than 3000 pulses. Since LIPSS was less formed with lower repetition rate, certain heat accumulation may be required for LIPSS formation. With the pulse duration of 2.0 ps, higher laser fluence as well as number of pulses compared to the case of 120 fs was necessary. This indicates that multiphoton absorption process is essential for LIPSS formation. Study on biodegradation modification was also performed.

  3. In situ aerosol characterization at Cape Verde. Part 2: Parametrization of relative humidity- and wavelength-dependent aerosol optical properties

    Energy Technology Data Exchange (ETDEWEB)

    Schladitz, Alexander; Muller, Thomas; Nordmann, Stephan; Tesche, Matthias; Wiedensohler, Alfred (Leibniz Institute for Tropospheric Research (IfT), Leipzig (Germany)), e-mail: alexander.schladitz@tropos.de; Gross, Silke; Freudenthaler, Volker; Gasteiger, Josef (Meteorological Institute, Ludwig-Maximilians-Universitaet, Munich (Germany))

    2011-09-15

    An observation-based numerical study of humidity-dependent aerosol optical properties of mixed marine and Saharan mineral dust aerosol is presented. An aerosol model was developed based on measured optical and microphysical properties to describe the marine and Saharan dust aerosol at Cape Verde. A wavelength-dependent optical equivalent imaginary part of the refractive index and a scattering non-sphericity factor for Saharan dust were derived. Simulations of humidity effects on optical properties by the aerosol model were validated with relative measurements of the extinction coefficient at ambient conditions. Parametrizations were derived to describe the humidity dependence of the extinction, scattering, and absorption coefficients as well as the asymmetry parameter and single scattering albedo. For wavelengths (300-950 nm) and dry dust volume fractions (0-1), aerosol optical properties as a function of relative humidity (RH = 0-90%) can be calculated from tabulated parameters. For instance, at a wavelength of 550 nm, a volume fraction of 0.5 of dust on the total particle volume (dry conditions) and a RH of 90%, the enhancements for the scattering, extinction and absorption coefficients are 2.55, 2.46 and 1.04, respectively, while the enhancements for the asymmetry parameter and single scattering albedo are 1.11 and 1.04

  4. Optical properties of erbium-doped porous silicon waveguides

    Energy Technology Data Exchange (ETDEWEB)

    Najar, A. [Laboratoire d' Optronique UMR 6082-FOTON, Universite de Rennes 1, 6 rue de Kerampont, B P. 80518, 22305 Lannion Cedex (France); Laboratoire de Spectroscopie Raman, Faculte des Sciences de Tunis, 2092 ElManar, Tunis (Tunisia); Charrier, J. [Laboratoire d' Optronique UMR 6082-FOTON, Universite de Rennes 1, 6 rue de Kerampont, B P. 80518, 22305 Lannion Cedex (France)]. E-mail: joel.charier@univ-rennes1.fr; Ajlani, H. [Laboratoire de Spectroscopie Raman, Faculte des Sciences de Tunis, 2092 ElManar, Tunis (Tunisia); Lorrain, N. [Laboratoire d' Optronique UMR 6082-FOTON, Universite de Rennes 1, 6 rue de Kerampont, B P. 80518, 22305 Lannion Cedex (France); Elhouichet, H. [Laboratoire de Spectroscopie Raman, Faculte des Sciences de Tunis, 2092 ElManar, Tunis (Tunisia); Oueslati, M. [Laboratoire de Spectroscopie Raman, Faculte des Sciences de Tunis, 2092 ElManar, Tunis (Tunisia); Haji, L. [Laboratoire d' Optronique UMR 6082-FOTON, Universite de Rennes 1, 6 rue de Kerampont, B P. 80518, 22305 Lannion Cedex (France)

    2006-12-15

    Planar and buried channel porous silicon waveguides (WG) were prepared from p{sup +}-type silicon substrate by a two-step anodization process. Erbium ions were incorporated into pores of the porous silicon layers by an electrochemical method using ErCl{sub 3}-saturated solution. Erbium concentration of around 10{sup 20} at/cm{sup 3} was determined by energy-dispersive X-ray analysis performed on SEM cross-section. The luminescence properties of erbium ions in the IR range were determined and a luminescence time decay of 420 {mu}s was measured. Optical losses were studied on these WG. The increased losses after doping were discussed.

  5. Structural, electronic and optical properties of carbon nitride

    Energy Technology Data Exchange (ETDEWEB)

    Cohen, M L [California Univ., Berkeley (United States). Dept. of Physics

    1996-05-01

    Carbon nitride was proposed as a superhard material and a structural prototype, {beta}-C{sub 3}N{sub 4}, was examined using several theoretical models. Some reports claiming experimental verifications have been made recently. The current status of the theory and experiment is reviewed, and a detailed discussion is presented of calculations of the electronic and optical properties of this material. These calculations predict that {beta}-C{sub 3}N{sub 4} will have a minimum gap which is indirect at 6.4{+-}0.5 eV. A discussion of the possibility of carbon nitride nanotubes is also presented. (orig.)

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

    Science.gov (United States)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    George, Preetha Mary, E-mail: preethageoti@gmail.com, E-mail: jayakumars030@gmail.com; Divya, P. [Department of Physics, Dr M.G.R Educational and Research Institute University Chennai- (India); Jayakumar, S., E-mail: preethageoti@gmail.com, E-mail: jayakumars030@gmail.com; Subhashree, N. S. [Department of Physics, RKM Vivekananda College, Chennai-600004 (India); Ahmed, M. Anees [Department of Physics, New College, Chennai (India)

    2015-06-24

    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.

  8. Liquidus temperature and optical properties measurement by containerless techniques

    Science.gov (United States)

    Anderson, Collin D.

    1993-01-01

    Reactive alloy liquidus temperatures measured by conventional, contained techniques are often in error due to reactions with containers and gaseous impurities. This paper describes a new liquidus temperature measurement technique that avoids these problems by employing containerless processing. This technique relies on precise and accurate noncontact temperature measurements (NCTM), which are made possible by spectral emissivity values. The spectral emissivities, epsilon(sub lambda), are measured along with the optical properties (real, n, and imaginary, k, components of the index of refraction) using polarimetric techniques on electromagnetically levitated specimens. Results from work done at Vanderbilt University and Intersonics on the Ti-Al system are presented to demonstrate the above techniques.

  9. Optical And Environmental Properties Of NCAP Glazing Products

    Science.gov (United States)

    van Konynenburg, Peter; Wipfler, Richard T.; Smith, Jerry L.

    1989-07-01

    The first large area, commercially available, electrically-controllable glazing products sold under the tradename VARILITETM are based on a new liquid crystal film technology called NCAP. The glazing products can be switched in milliseconds between a highly translucent state (for privacy and glare control) to a transparent state (for high visibility) with the application of an AC voltage. The optical and environmental properties are demonstrated to meet the general requirements for architectural glazing use. The first qualified indoor product is described in detail.

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

    International Nuclear Information System (INIS)

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

    2015-01-01

    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

  11. Structural, optical and dielectric properties of graphene oxide

    Science.gov (United States)

    Bhargava, Richa; Khan, Shakeel

    2018-05-01

    The Modified Hummers method has been used to synthesize Graphene oxide nanoparticles. Microstructural analyses were carried out by X-ray diffraction and Fourier transform infrared spectroscopy. Optical properties were studied by UV-visible spectroscopy in the range of 200-700 nm. The energy band gap was calculated with the help of Tauc relation. The frequency dependence of dielectric constant and dielectric loss were studied over a range of the frequency 75Hz to 5MHz at room temperature. The dispersion in dielectric constant can be explained with the help of Maxwell-Wagner model in studied nanoparticles.

  12. Optical constants and structural properties of thin gold films

    DEFF Research Database (Denmark)

    Yakubovsky, Dmitry I.; Arsenin, Aleksey V.; Stebunov, Yury V.

    2017-01-01

    We report a comprehensive experimental study of optical and electrical properties of thin polycrystalline gold films in a wide range of film thicknesses (from 20 to 200 nm). Our experimental results are supported by theoretical calculations based on the measured morphology of the fabricated gold...... rules for thin-film plasmonic and nanophotonic devices....... films. We demonstrate that the dielectric function of the metal is determined by its structural morphology. Although the fabrication process can be absolutely the same for different films, the dielectric function can strongly depend on the film thickness. Our studies show that the imaginary part...

  13. Improved theoretical model of InN optical properties

    International Nuclear Information System (INIS)

    Ferreira da Silva, A.; Chubaci, J.F.D.; Matsuoka, M.; Freitas, J.A. Jr.; Tischler, J.G.; Baldissera, G.; Persson, C.

    2014-01-01

    The optical properties of InN are investigated theoretically by employing the projector augmented wave (PAW) method within Green's function and the screened Coulomb interaction approximation (GW o ). The calculated results are compared to previously reported calculations which use local density approximation combined with the scissors-operator approximation. The results of the present calculation are compared with reported values of the InN bandgap and with low temperature near infrared luminescence measurements of InN films deposited by a modified Ion Beam Assisted Deposition technique. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  14. Quantum theory of the optical and electronic properties of semiconductors

    CERN Document Server

    Haug, Hartmut

    1990-01-01

    The current technological revolution in the development of computing devices has created a demand for a textbook on the quantum theory of the electronic and optical properties of semiconductors and semiconductor devices. This book successfully fulfills this need. Based on lectures given by the authors, it is a comprehensive introduction for researchers or graduate-level students to the subject. Certain sections can also serve as a graduate-level textbook for use in solid state physics courses or for more specialized courses. The final chapters establish a direct link to current research in sem

  15. Thin nanodiamond membranes and their microstructural, optical and photoelectrical properties

    Czech Academy of Sciences Publication Activity Database

    Mortet, V.; D´Haen, J.; Potměšil, Jiří; Kravets, Roman; Drbohlav, Ivo; Vorlíček, Vladimír; Rosa, Jan; Vaněček, Milan

    2005-01-01

    Roč. 14, - (2005), s. 393-397 ISSN 0925-9635 R&D Projects: GA MŠk(CZ) LN00A015; GA ČR(CZ) GA202/05/2233; GA MŠk(CZ) LC510 EU Projects: European Commission(XE) HPRN-CT-1999-00139 Institutional research plan: CEZ:AV0Z10100521 Keywords : nanodiamond * structural characterization * optical properties * defect spectroscopy Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.988, year: 2005

  16. Geometrical-optics code for computing the optical properties of large dielectric spheres.

    Science.gov (United States)

    Zhou, Xiaobing; Li, Shusun; Stamnes, Knut

    2003-07-20

    Absorption of electromagnetic radiation by absorptive dielectric spheres such as snow grains in the near-infrared part of the solar spectrum cannot be neglected when radiative properties of snow are computed. Thus a new, to our knowledge, geometrical-optics code is developed to compute scattering and absorption cross sections of large dielectric particles of arbitrary complex refractive index. The number of internal reflections and transmissions are truncated on the basis of the ratio of the irradiance incident at the nth interface to the irradiance incident at the first interface for a specific optical ray. Thus the truncation number is a function of the angle of incidence. Phase functions for both near- and far-field absorption and scattering of electromagnetic radiation are calculated directly at any desired scattering angle by using a hybrid algorithm based on the bisection and Newton-Raphson methods. With these methods a large sphere's absorption and scattering properties of light can be calculated for any wavelength from the ultraviolet to the microwave regions. Assuming that large snow meltclusters (1-cm order), observed ubiquitously in the snow cover during summer, can be characterized as spheres, one may compute absorption and scattering efficiencies and the scattering phase function on the basis of this geometrical-optics method. A geometrical-optics method for sphere (GOMsphere) code is developed and tested against Wiscombe's Mie scattering code (MIE0) and a Monte Carlo code for a range of size parameters. GOMsphere can be combined with MIE0 to calculate the single-scattering properties of dielectric spheres of any size.

  17. Enhancing optical nonreciprocity by an atomic ensemble in two coupled cavities

    Science.gov (United States)

    Song, L. N.; Wang, Z. H.; Li, Yong

    2018-05-01

    We study the optical nonreciprocal propagation in an optical molecule of two coupled cavities with one of them interacting with a two-level atomic ensemble. The effect of increasing the number of atoms on the optical isolation ratio of the system is studied. We demonstrate that the significant nonlinearity supplied by the coupling of the atomic ensemble with the cavity leads to the realization of greatly-enhanced optical nonreciprocity compared with the case of single atom.

  18. Time-domain scanning optical mammography: II. Optical properties and tissue parameters of 87 carcinomas

    International Nuclear Information System (INIS)

    Grosenick, Dirk; Wabnitz, Heidrun; Moesta, K Thomas; Mucke, Joerg; Schlag, Peter M; Rinneberg, Herbert

    2005-01-01

    Within a clinical trial on scanning time-domain optical mammography reported on in a companion publication (part I), craniocaudal and mediolateral projection optical mammograms were recorded from 154 patients, suspected of having breast cancer. Here we report on in vivo optical properties of the subset of 87 histologically validated carcinomas which were visible in optical mammograms recorded at two or three near-infrared wavelengths. Tumour absorption and reduced scattering coefficients were derived from distributions of times of flight of photons recorded at the tumour site employing the model of diffraction of photon density waves by a spherical inhomogeneity, located in an otherwise homogeneous tissue slab. Effective tumour radii, taken from pathology, and tumour location along the compression direction, deduced from off-axis optical scans of the tumour region, were included in the analysis as prior knowledge, if available. On average, tumour absorption coefficients exceeded those of surrounding healthy breast tissue by a factor of about 2.5 (670 nm), whereas tumour reduced scattering coefficients were larger by about 20% (670 nm). From absorption coefficients at 670 nm and 785 nm total haemoglobin concentration and blood oxygen saturation were deduced for tumours and surrounding healthy breast tissue. Apart from a few outliers total haemoglobin concentration was observed to be systematically larger in tumours compared to healthy breast tissue. In contrast, blood oxygen saturation was found to be a poor discriminator for tumours and healthy breast tissue; both median values of blood oxygen saturation are the same within their statistical uncertainties. However, the ratio of total haemoglobin concentration over blood oxygen saturation further improves discrimination between tumours and healthy breast tissue. For 29 tumours detected in optical mammograms recorded at three wavelengths (670 nm, 785 nm, 843 nm or 884 nm), scatter power was derived from transport

  19. Nonlinear optical properties of an electromagnetically induced transparency medium interacting with two quantized fields

    CERN Document Server

    Kuang-Leman; Wu Yong Shi

    2003-01-01

    We study linear and nonlinear optical properties of an electromagnetically induced transparency (EIT) medium interacting with two quantized laser fields in the adiabatic EIT case. We show that the EIT medium exhibits normal dispersion. Kerr and higher-order nonlinear refractive index coefficients are also calculated in a completely analytical form. It is indicated that the EIT medium exhibits giant resonantly enhanced nonlinearities. We discuss the response of the EIT medium to nonclassical light fields and find that the polarization vanishes when the probe laser is initially in a nonclassical state of no single-photon coherence.

  20. The structural heterogeneity and optical properties in chalcogenide glass films

    International Nuclear Information System (INIS)

    Shurgalin, Max; Fuflyigin, Vladimir N; Anderson, Emilia G

    2005-01-01

    The microscopic structure and optical properties of glassy films prepared by vapour phase deposition process from the germanium-arsenic-selenium family of chalcogenide glasses have been studied. A number of different molecular clusters or domains that can exist in the glass structure are found to play a significant role in determining the absorption characteristics and refractive index of the glass films. Modifications of the glass structure can be described by a variation of relative concentrations of the clusters and can be effected by modifications of film chemical composition and deposition conditions. Changes in absorption spectra are directly correlated with variation in relative concentrations of the structural fragments with different electronic bandgap properties. Experimental results suggest structural heterogeneity and support validity of the cluster structural model for the chalcogenide glasses

  1. Optical properties of quantum-dot-doped liquid scintillators

    International Nuclear Information System (INIS)

    Aberle, C; Winslow, L; Li, J J; Weiss, S

    2013-01-01

    Semiconductor nanoparticles (quantum dots) were studied in the context of liquid scintillator development for upcoming neutrino experiments. The unique optical and chemical properties of quantum dots are particularly promising for the use in neutrinoless double-beta decay experiments. Liquid scintillators for large scale neutrino detectors have to meet specific requirements which are reviewed, highlighting the peculiarities of quantum-dot-doping. In this paper, we report results on laboratory-scale measurements of the attenuation length and the fluorescence properties of three commercial quantum dot samples. The results include absorbance and emission stability measurements, improvement in transparency due to filtering of the quantum dot samples, precipitation tests to isolate the quantum dots from solution and energy transfer studies with quantum dots and the fluorophore PPO

  2. Syntheses and optical properties of triphenylene-containing conjugated polymers

    International Nuclear Information System (INIS)

    Chou, C.-E.; Wang Degang; Bagui, Mahuya; Hsu, Jeffrey; Chakraborty, Sanjiban; Peng Zhonghua

    2010-01-01

    In this paper, we report the detailed synthesis and optical properties of three new conjugated polymers containing triphenylene units in the backbone. Polymer PTPT exhibits strong folding propensity and forms foldamers in both polar and nonpolar solvents. PTPA, with two long alkyl chains attached to the bridging phenyl ring, exhibits mainly as interchain aggregates in 'poor' solvents (DMSO and acetonitrile), but adopts a folding conformation in solvent mixtures with a high poor solvent content. PTPV, on the other hand, adopts a random nonfolding conformation in both polar and nonpolar solvents. The low folding propensity of PTPV is likely due to the added geometrical flexibility of the vinyl bonds. Among the three polymers, PTPV is most fluorescent with a fluorescence quantum yield as high as 0.87, suggesting its potential applications as light-emitting materials or fluorescence-based sensors. PTPT, on the other hand, with its strong folding property, may find applications as efficient charge-transporting materials.

  3. Laser-ablated silicon nanoparticles: optical properties and perspectives in optical coherence tomography

    International Nuclear Information System (INIS)

    Kirillin, M Yu; Sergeeva, E A; Agrba, P D; Krainov, A D; Ezhov, A A; Shuleiko, D V; Kashkarov, P K; Zabotnov, S V

    2015-01-01

    Due to their biocompatibility silicon nanoparticles have high potential in biomedical applications, especially in optical diagnostics. In this paper we analyze properties of the silicon nanoparticles formed via laser ablation in water and study the possibility of their application as contrasting agents in optical coherence tomography (OCT). The nanoparticles suspension was produced by picosecond laser irradiation of monocrystalline silicon wafers in water. According to transmission electron microcopy analysis the silicon nanoparticles in the obtained suspension vary in size from 2 to 200 nm while concentration of the particles is estimated as 10 13 cm −3 . The optical properties of the suspension in the range from 400 to 1000 nm were studied by spectrophotometry measurements revealing a scattering coefficient of about 0.1 mm −1 and a scattering anisotropy factor in the range of 0.2–0.4. In OCT study a system with a central wavelength of 910 nm was employed. Potential of the silicon nanoparticles as a contrasting agent for OCT is studied in experiments with agarose gel phantoms. Topical application of the nanoparticles suspension allowed the obtaining of the contrast of structural features of phantom up to 14 dB in the OCT image. (paper)

  4. Integrated optical and electrical modeling of plasmon-enhanced thin film photovoltaics: A case-study on organic devices

    International Nuclear Information System (INIS)

    Rourke, Devin; Ahn, Sungmo; Nardes, Alexandre M.; Lagemaat, Jao van de; Kopidakis, Nikos; Park, Wounjhang

    2014-01-01

    The nanoscale light control for absorption enhancement of organic photovoltaic (OPV) devices inevitably produces strongly non-uniform optical fields. These non-uniformities due to the localized optical modes are a primary route toward absorption enhancement in OPV devices. Therefore, a rigorous modeling tool taking into account the spatial distribution of optical field and carrier generation is necessary. Presented here is a comprehensive numerical model to describe the coupled optical and electrical behavior of plasmon-enhanced polymer:fullerene bulk heterojunction (BHJ) solar cells. In this model, a position-dependent electron-hole pair generation rate that could become highly non-uniform due to photonic nanostructures is directly calculated from the optical simulations. By considering the absorption and plasmonic properties of nanophotonic gratings included in two different popular device architectures, and applying the Poisson, current continuity, and drift/diffusion equations, the model predicts quantum efficiency, short-circuit current density, and desired carrier mobility ratios for bulk heterojunction devices incorporating nanostructures for light management. In particular, the model predicts a significant degradation of device performance when the carrier species with lower mobility are generated far from the collecting electrode. Consequently, an inverted device architecture is preferred for materials with low hole mobility. This is especially true for devices that include plasmonic nanostructures. Additionally, due to the incorporation of a plasmonic nanostructure, we use simulations to theoretically predict absorption band broadening of a BHJ into energies below the band gap, resulting in a 4.8% increase in generated photocurrent.

  5. Integrated optical and electrical modeling of plasmon-enhanced thin film photovoltaics: A case-study on organic devices

    Energy Technology Data Exchange (ETDEWEB)

    Rourke, Devin [Department of Physics, University of Colorado, Boulder, Colorado 80309-0390 (United States); Ahn, Sungmo [Department of Electrical, Computer, and Energy Engineering, University of Colorado, Boulder, Colorado 80309-0425 (United States); Nardes, Alexandre M.; Lagemaat, Jao van de; Kopidakis, Nikos [National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, Colorado 80401 (United States); Park, Wounjhang, E-mail: won.park@colorado.edu [Department of Electrical, Computer, and Energy Engineering, University of Colorado, Boulder, Colorado 80309-0425 (United States); Materials Science and Engineering Program, University of Colorado, Boulder, Colorado 80303 (United States)

    2014-09-21

    The nanoscale light control for absorption enhancement of organic photovoltaic (OPV) devices inevitably produces strongly non-uniform optical fields. These non-uniformities due to the localized optical modes are a primary route toward absorption enhancement in OPV devices. Therefore, a rigorous modeling tool taking into account the spatial distribution of optical field and carrier generation is necessary. Presented here is a comprehensive numerical model to describe the coupled optical and electrical behavior of plasmon-enhanced polymer:fullerene bulk heterojunction (BHJ) solar cells. In this model, a position-dependent electron-hole pair generation rate that could become highly non-uniform due to photonic nanostructures is directly calculated from the optical simulations. By considering the absorption and plasmonic properties of nanophotonic gratings included in two different popular device architectures, and applying the Poisson, current continuity, and drift/diffusion equations, the model predicts quantum efficiency, short-circuit current density, and desired carrier mobility ratios for bulk heterojunction devices incorporating nanostructures for light management. In particular, the model predicts a significant degradation of device performance when the carrier species with lower mobility are generated far from the collecting electrode. Consequently, an inverted device architecture is preferred for materials with low hole mobility. This is especially true for devices that include plasmonic nanostructures. Additionally, due to the incorporation of a plasmonic nanostructure, we use simulations to theoretically predict absorption band broadening of a BHJ into energies below the band gap, resulting in a 4.8% increase in generated photocurrent.

  6. Science Data Report for the Optical Properties Monitor (OPM) Experiment

    Science.gov (United States)

    Wilkes, D. R.; Zwiener, J. M.; Carruth, Ralph (Technical Monitor)

    2001-01-01

    This science data report describes the Optical Properties Monitor (OPM) experiment and the data gathered during its 9-mo exposure on the Mir space station. Three independent optical instruments made up OPM: an integrating sphere spectral reflectometer, vacuum ultraviolet spectrometer, and a total integrated scatter instrument. Selected materials were exposed to the low-Earth orbit, and their performance monitored in situ by the OPM instruments. Coinvestigators from four NASA Centers, five International Space Station contractors, one university, two Department of Defense organizations, and the Russian space company, Energia, contributed samples to this experiment. These materials included a number of thermal control coatings, optical materials, polymeric films, nanocomposites, and other state-of-the-art materials. Degradation of some materials, including aluminum conversion coatings and Beta cloth, was greater than expected. The OPM experiment was launched aboard the Space Shuttle on mission STS-81 in January 1997 and transferred to the Mir space station. An extravehicular activity (EVA) was performed in April 1997 to attach the OPM experiment to the outside of the Mir/Shuttle Docking Module for space environment exposure. OPM was retrieved during an EVA in January 1998 and was returned to Earth on board the Space Shuttle on mission STS-89.

  7. Effect of radiation on the optical properties of some ferroelectrics

    International Nuclear Information System (INIS)

    Pirogova, G.N.; Kritskaya, V.E.; Malov, N.A.; Ryabov, A.I.; Voronin, Y.V.

    1986-01-01

    This paper studies the effect of gamma-irradiation and impulsive irradiation with electrons on the optical properties of crystals used in nonlinear optics: potassium dihydrophosphate KH 2 PO 4 , and cesium dihydroarsenate CsH 2 AsO 4 . The authors used two types of crystals obtained by extraction of the condensate, lowering of the temperature and recirculation. The content of iron-group impurity atoms (A1, Cu, and Mg) were determined with the help of atomic absorption spectrometry and was less than 1.10 -3 mole %. The samples were irradiated with a Co 60 gamma-ray source and impulsive irradiation with electrons was performed with a U-12 linear accelerator. A comparison of the spectra of gamma-irradiated single crystals and crystals irradiated with electrons shows that they are identical in the UV region. The impulse technique, however, enables observing the absorption bands which under gamma-irradiation are lost owing to the large increment of the optical density in the ultraviolet region and the shift of the absorption edge into the long-wavelength region

  8. Optical properties of electrically connected plasmonic nanoantenna dimer arrays

    Science.gov (United States)

    Zimmerman, Darin T.; Borst, Benjamin D.; Carrick, Cassandra J.; Lent, Joseph M.; Wambold, Raymond A.; Weisel, Gary J.; Willis, Brian G.

    2018-02-01

    We fabricate electrically connected gold nanoantenna arrays of homodimers and heterodimers on silica substrates and present a systematic study of their optical properties. Electrically connected arrays of plasmonic nanoantennas make possible the realization of novel photonic devices, including optical sensors and rectifiers. Although the plasmonic response of unconnected arrays has been studied extensively, the present study shows that the inclusion of nanowire connections modifies the device response significantly. After presenting experimental measurements of optical extinction for unconnected dimer arrays, we compare these to measurements of dimers that are interconnected by gold nanowire "busbars." The connected devices show the familiar dipole response associated with the unconnected dimers but also show a second localized surface plasmon resonance (LSPR) that we refer to as the "coupled-busbar mode." Our experimental study also demonstrates that the placement of the nanowire along the antenna modifies the LSPR. Using finite-difference time-domain simulations, we confirm the experimental results and investigate the variation of dimer gap and spacing. Changing the dimer gap in connected devices has a significantly smaller effect on the dipole response than it does in unconnected devices. On the other hand, both LSPR modes respond strongly to changing the spacing between devices in the direction along the interconnecting wires. We also give results for the variation of E-field strength in the dimer gap, which will be important for any working sensor or rectenna device.

  9. Optical properties of cosmic dust analogs: a review

    Science.gov (United States)

    Henning, Thomas; Mutschke, Harald

    2010-04-01

    Nanometer- and micrometer-sized solid particles play an important role in the evolutionary cycle of stars and interstellar matter. The optical properties of cosmic grains determine the interaction of the radiation field with the solids, thereby regulating the temperature structure and spectral appearance of dusty regions. Radiation pressure on dust grains and their collisions with the gas atoms and molecules can drive powerful winds. The analysis of observed spectral features, especially in the infrared wavelength range, provides important information on grain size, composition and structure as well as temperature and spatial distribution of the material. The relevant optical data for interstellar, circumstellar, and protoplanetary grains can be obtained by measurements on cosmic dust analogs in the laboratory or can be calculated from grain models based on optical constants. Both approaches have made progress in the last years, triggered by the need to interpret increasingly detailed high-quality astronomical observations. The statistical theoretical approach, spectroscopic experiments at variable temperature and absorption spectroscopy of aerosol particulates play an important role for the successful application of the data in dust astrophysics.

  10. Optical investigation of niobium properties: Electrical- and physical constants

    Science.gov (United States)

    Singh, Nageshwar; Deo, M. N.; Roy, S. B.

    2017-08-01

    In this paper, we report optical (reflectance) measurements and investigations of optical properties of electropolished (EP), buffered chemical polished (BCP), and as-received (AR) from vendor niobium (Nb) samples typically used for fabrication of superconducting radio frequency (SCRF) cavities. Optical conductivity (σ(0), approximated near zero frequency) of EP (σ(0) ∼ 9 × 103 Ω-1 cm-1) sample is one order of magnitude higher than that of BCP (σ(0) ∼ 7 × 102 Ω-1 cm-1) and AR (σ(0) ∼ 3 × 102 Ω-1 cm-1) niobium samples. Furthermore, physical constants of electropolished Nb-SCRF materials such as concentration of conduction electrons (∼ 1.8 × 1022 electrons/cm3), average velocity (∼ 5.9 × 107 cm/s) of the electrons on the Fermi surface, and mean free path (∼ 0.53 nm) were also found to be considerably higher than that of the BCP and the AR samples. The depth of electric field penetration (in low frequency region) in the electropolished Nb sample (∼ 80 nm) is appreciably lesser than the BCP (∼ 450 nm) and the AR (∼ 400 nm) samples.

  11. Optical properties of likely constituents of interstellar dust

    International Nuclear Information System (INIS)

    Dayawansa, I.J.

    1977-07-01

    Optical properties of polyoxymethylene (POM) at room temperature have been measured from the near ultra-violet to infrared as an initial stage of a link between interstellar dust and organic matter, and the results, which are particularly relevant to interstellar extinction, are reported. There is a strong possibility of a more complex organic component which could significantly contribute to the interstellar extinction. Measurements have also been made of the effect of fast neutron bombardment on the optical properties of quartz (SiO 2 ). At a high total flux of neutrons the crystalline quartz will change to its amorphous form which has extinction properties that resemble the interstellar extinction. Extinction due to small particles of several forms of SiO 2 has been measured and among them the hydrated mineral, opal, behaved like an amorphous silica. Neutron irradiated olivine showed a stronger and a broader 10μm band in addition to weaker bands towards the longer wavelengths which indicated that atomic damage has been produced. At high fluxes more atomic damage is expected to change the crystalline structure and thereby cause changes in the infrared absorption properties. Extinction measurements were also made for smoke particles of MgO in the infrared. When the measurements were made with the particles deposited on substrates, in addition to a very broad surface mode absorption feature around 20μm an extinction maximum was observed typical of the bulk mode at 25μm. Extinction measurements for MgO smoke particles in air also showed similar results. However when the particles were dispersed in a non-absorbing medium, the bulk absorption mode was not observed. This implies that the appearance of the bulk mode is due to clumping. (author)

  12. ZnS-Graphene nanocomposite: Synthesis, characterization and optical properties

    Energy Technology Data Exchange (ETDEWEB)

    Pan Shugang [Key Laboratory for Soft Chemistry and Functional Materials, Nanjing University of Science and Technology, Ministry of Education, Nanjing 210094 (China); Liu Xiaoheng, E-mail: xhliu@mail.njust.edu.cn [Key Laboratory for Soft Chemistry and Functional Materials, Nanjing University of Science and Technology, Ministry of Education, Nanjing 210094 (China)

    2012-07-15

    A ZnS-Graphene nanocomposite was prepared by a facile one-step hydrothermal method using zinc nitrate hexahydrate, ethylenediamine and carbon disulfide as precursors, graphene oxide as a template. The composite was characterized by X-ray power diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, Fourier transform infrared, Raman spectra and fluorescence spectroscopy. The results show that graphene oxide was reduced to graphene in the hydrothermal reaction process. Simultaneously, the graphene sheets in the composite are exfoliated and decorated with ZnS nanoparticles. Furthermore, Raman and fluorescence properties of the composite were observed. ZnS-Graphene nanocomposite displays surface-enhanced Raman scattering activity for graphene oxide, and fluorescence enhancement property compared with pure ZnS sample. - Graphical abstract: Approach of reaction makes the reduction of grapheme oxide and the deposition of Zns on the grapheme sheets occur simultaneously and overcomes the aggregation of the grapheme sheets and Zns. Highlights: Black-Right-Pointing-Pointer Graphene oxide is reduced to graphene in the hydrothermal reaction process. Black-Right-Pointing-Pointer ZnS nanoparticles are attached onto the almost transparent graphene sheets. Black-Right-Pointing-Pointer ZnS-Graphene system shows surface-enhanced Raman scattering (SERS) activity. Black-Right-Pointing-Pointer ZnS-Graphene system displays relatively better fluorescence property than pure ZnS.

  13. Modifying the electronic and optical properties of carbon nanotubes

    Science.gov (United States)

    Kinder, Jesse M.

    The intrinsic electronic and optical properties of carbon nanotubes make them promising candidates for circuit elements and LEDs in nanoscale devices. However, applied fields and interactions with the environment can modify these intrinsic properties. This dissertation is a theoretical study of perturbations to an ideal carbon nanotube. It illustrates how transport and optical properties of carbon nanotubes can be adversely affected or intentionally modified by the local environment. The dissertation is divided into three parts. Part I analyzes the effect of a transverse electric field on the single-electron energy spectrum of semiconducting carbon nanotubes. Part II analyzes the effect of the local environment on selection rules and decay pathways relevant to dark excitons. Part III is a series of 26 appendices. Two different models for a transverse electric field are introduced in Part I. The first is a uniform field perpendicular to the nanotube axis. This model suggests the field has little effect on the band gap until it exceeds a critical value that can be tuned with strain or a magnetic field. The second model is a transverse field localized to a small region along the nanotube axis. The field creates a pair of exponentially localized bound states but has no effect on the band gap for particle transport. Part II explores the physics of dark excitons in carbon nanotubes. Two model calculations illustrate the effect of the local environment on allowed optical transitions and nonradiative recombination pathways. The first model illustrates the role of inversion symmetry in the optical spectrum. Broken inversion symmetry may explain low-lying peaks in the exciton spectrum of boron nitride nanotubes and localized photoemission around impurities and interfaces in carbon nanotubes. The second model in Part II suggests that free charge carriers can mediate an efficient nonradiative decay process for dark excitons in carbon nanotubes. The appendices in Part III

  14. Press forging and optical properties of lithium fluoride

    Science.gov (United States)

    Ready, J. F.; Vora, H.

    1980-07-01

    Lithium fluoride is an important candidate material for windows on high power, short-pulse ultraviolet and visible lasers. Lithium fluoride crystals were press forged in one step over the temperature range 300 to 600 C to obtain fine grained polycrystalline material with improved mechanical properties. The deformation that can be given to a lithium fluoride crystal during forging is limited by the formation of internal cloudiness (veiling) with the deformation limit increasing with increasing forging temperature from about 40 percent at 400 C to 65 percent at 600 C. To suppress veiling, lithium fluoride crystals were forged in two steps over the temperature range 300 to 600 C, to total deformations of 69 to 76 percent, with intermediate annealing at 700 C. This technique yields a material which has lower scattering with more homogeneous microstructure than that obtained in one step forging. The results of characterization of various optical and mechanical properties of single crystal and forged lithium fluoride, including scattering, optical homogeneity, residual absorption, damage thresholds, environmental stability, and thresholds for microyield are described.

  15. Press forging and optical properties of lithium fluoride

    International Nuclear Information System (INIS)

    Ready, J.F.; Vora, H.

    1979-01-01

    Lithium fluoride is an important candidate material for windows on high-power, short-pulse ultraviolet and visible lasers. Lithium fluoride crystals have been press forged in one step over the temperature range 300 to 600 0 c to obtain fine-grained polycrystalline material with improved mechanical properties. The deformation that can be given to a lithium fluoride crystal during forging is limited by the formation of internal cloudiness (veiling) with the deformation limit increasing with increasing forging temperature from about 40% at 400 0 C to 65% at 600 0 C. To suppress veiling, lithium fluoride crystals were forged in two steps over the temperature range 300 to 600 0 C, to total deformations of 69-76%, with intermediate annealing at 700 0 C. This technique yields a material which has lower scattering with more homogeneous microstructure than that obtained in one-step forging. The results of characterization of various optical and mechanical properties of single-crystal and forged lithium fluoride, including scattering, optical homogeneity, residual absorption, damage thresholds, environmental stability, and thresholds for microyield are described

  16. Geometry, electronic structures and optical properties of phosphorus nanotubes

    International Nuclear Information System (INIS)

    Hu, Tao; Hashmi, Arqum; Hong, Jisang

    2015-01-01

    Using a first principles approach, we investigated the geometry, electronic structures, and optical properties of phosphorus nanotubes (PNTs). Two possible 1D configurations, the so-called α-PNTs and β-PNTs, are proposed, which are structurally related to blue and black phosphorus monolayers, respectively. Hereby, we predict that both armchair and zigzag geometries can be synthesized in α-PNTs, but the zigzag form of β-PNT is highly unfavorable because of large strain and conformation energies. The band gap of α-PNTs is expected to be ∼2.67 eV, and this is insensitive to the chirality when the tube’s inner diameter is larger than 1.3 nm, while the armchair β-PNTs have a much smaller band gap. Interestingly, we find nearly flat band structures in the zigzag α-PNT system. This may indicate that an excited particle–hole pair has a huge effective mass. We also find asymmetric optical properties with respect to the polarization direction. The armchair α-PNT for parallel polarization shows a large refractive index of 2.6 near the ultraviolet wavelength, and also we find that the refractive index can be even smaller than 1 in certain frequency ranges. The zigzag tubes show very weak reflectivity for parallel polarization, while the armchair tube displays high reflectivity. (paper)

  17. Optical properties of alumina membranes prepared by anodic oxidation process

    International Nuclear Information System (INIS)

    Li Zhaojian; Huang Kelong

    2007-01-01

    The luminescence property of anodic alumina membranes (AAMs) with ordered nanopore arrays prepared by electrochemically anodizing aluminum in oxalic acid solutions have been investigated. Photoluminescence emission (PL) measurement shows that a blue PL band occurs in the wavelength ranges of 300-600 nm. The PL intensity and peak position of AAMs depend markedly on the excitation wavelength. A new peak located at 518 nm can be observed under a monitoring wavelength at 429 nm in the photoluminescence excitation (PLE) spectra. Convincing evidences have been presented that the PLE would be associated with the residual aluminum ions in the membrane. The PLE and PL of AAMs, as a function of anodizing times, have been discussed. It is found that the oxalic impurities incorporated in the AAMs would have important influences on the optical properties of AAMs in the initial stage of anodization. The PL and PLE spectra obtained show that there are three optical centers, of which the first is originated from the F + centers in AAMs, the second is correlated with the oxalic impurities incorporated in the AAMs, and the third is associated with the excess aluminum ions in the membrane

  18. Optical properties of alumina membranes prepared by anodic oxidation process

    Energy Technology Data Exchange (ETDEWEB)

    Li Zhaojian [College of Chemistry and Chemical Engineering, Central South University, Changsha 410083 (China)], E-mail: lizhaojian_lzj@hotmail.com; Huang Kelong [College of Chemistry and Chemical Engineering, Central South University, Changsha 410083 (China)], E-mail: klhuang@mail.csu.edu.cn

    2007-12-15

    The luminescence property of anodic alumina membranes (AAMs) with ordered nanopore arrays prepared by electrochemically anodizing aluminum in oxalic acid solutions have been investigated. Photoluminescence emission (PL) measurement shows that a blue PL band occurs in the wavelength ranges of 300-600 nm. The PL intensity and peak position of AAMs depend markedly on the excitation wavelength. A new peak located at 518 nm can be observed under a monitoring wavelength at 429 nm in the photoluminescence excitation (PLE) spectra. Convincing evidences have been presented that the PLE would be associated with the residual aluminum ions in the membrane. The PLE and PL of AAMs, as a function of anodizing times, have been discussed. It is found that the oxalic impurities incorporated in the AAMs would have important influences on the optical properties of AAMs in the initial stage of anodization. The PL and PLE spectra obtained show that there are three optical centers, of which the first is originated from the F{sup +} centers in AAMs, the second is correlated with the oxalic impurities incorporated in the AAMs, and the third is associated with the excess aluminum ions in the membrane.

  19. Optical spectroscopic characterization of human meniscus biomechanical properties

    Science.gov (United States)

    Ala-Myllymäki, Juho; Danso, Elvis K.; Honkanen, Juuso T. J.; Korhonen, Rami K.; Töyräs, Juha; Afara, Isaac O.

    2017-12-01

    This study investigates the capacity of optical spectroscopy in the visible (VIS) and near-infrared (NIR) spectral ranges for estimating the biomechanical properties of human meniscus. Seventy-two samples obtained from the anterior, central, and posterior locations of the medial and lateral menisci of 12 human cadaver joints were used. The samples were subjected to mechanical indentation, then traditional biomechanical parameters (equilibrium and dynamic moduli) were calculated. In addition, strain-dependent fibril network modulus and permeability strain-dependency coefficient were determined via finite-element modeling. Subsequently, absorption spectra were acquired from each location in the VIS (400 to 750 nm) and NIR (750 to 1100 nm) spectral ranges. Partial least squares regression, combined with spectral preprocessing and transformation, was then used to investigate the relationship between the biomechanical properties and spectral response. The NIR spectral region was observed to be optimal for model development (83.0%≤R2≤90.8%). The percentage error of the models are: Eeq (7.1%), Edyn (9.6%), Eɛ (8.4%), and Mk (8.9%). Thus, we conclude that optical spectroscopy in the NIR range is a potential method for rapid and nondestructive evaluation of human meniscus functional integrity and health in real time during arthroscopic surgery.

  20. Optical properties of humic substances and CDOM: relation to structure.

    Science.gov (United States)

    Boyle, Erin S; Guerriero, Nicolas; Thiallet, Anthony; Del Vecchio, Rossana; Blough, Neil V

    2009-04-01

    The spectral dependencies of absorption and fluorescence emission (emission maxima (lamdamax), quantum yields (phi), and mean lifetimes (taum)) were acquired for a commercial lignin, Suwannee River humic (SRHA) and fulvic (SRFA) acids, and a series solid phase extracts (C18) from the Middle Atlantic Bight (MAB extracts). These parameters were compared with the relative average size and total lignin phenol content (TLP). TLP was strongly correlated with absorption at 280 and 355 nm for the MAB extracts, SRHA, and SRFA. The spectral dependence of lamdamax, phi), and taum was very similar for all samples, suggesting a common photophysical and thus structural basis. A strong decrease of phi and taum with increasing average size indicates that intramolecular interactions must be important. When combined with previous work, the results lead us to conclude that the optical properties commonly associated with terrestrial humic substances and chromophoric dissolved organic matter arise primarily from an ensemble of partially oxidized lignins derived from vascular plant sources. Theyfurther provide additional support for an electronic interaction model in which intramolecular energy transfer, excited-state electron transfer, as well as charge transfer likely play important roles in producing the observed optical and photochemical properties of these materials.

  1. Optical spectral properties of active galactic nuclei and quasars

    International Nuclear Information System (INIS)

    Yee, H.K.C.

    1981-01-01

    Four separate investigations dealing with the properties of optical continuum and emission-lines of active galactic nuclei (AGN) and quasars are presented. Multichannel scans of 3CR radio galaxies are decomposed by using a two-component model-an elliptical galaxy and a power-law nonthermal component. It is found that there is a strong correlation between the luminosity of the power-law component and the strength of the Balmer emission-lines. In most cases, by extrapolating to the Lyman continuum, the power-law models derived provide enough ionizing radiation to account for the Balmer line strengths. Extending the study of radio galaxies to include Seyfert galaxies and quasars, it is found that there is a strong continuity between broad-line AGN's and quasars in terms of similarities in the correlations between line luminosities and nonthermal continuum luminosity. Next, a study of the variability of absolute optical energy distribution and emission-lines of the N-galaxies 3C382 and 3C390.3 is made. Lastly, a preliminary study of surface photometry of Markarian Seyfert galaxies are presented. It is found that the properties of the underlying galaxies such as scale-length and surface brightness of the disk, color, and total brightness, do not depart systematically from those of luminous normal spiral galaxies

  2. Synthesis of Cu2O from CuO thin films: Optical and electrical properties

    Directory of Open Access Journals (Sweden)

    Dhanya S. Murali

    2015-04-01

    Full Text Available Hole conducting, optically transparent Cu2O thin films on glass substrates have been synthesized by vacuum annealing (5×10−6 mbar at 700 K for 1 hour of magnetron sputtered (at 300 K CuO thin films. The Cu2O thin films are p-type and show enhanced properties: grain size (54.7 nm, optical transmission 72% (at 600 nm and Hall mobility 51 cm2/Vs. The bulk and surface Valence band spectra of Cu2O and CuO thin films are studied by temperature dependent Hall effect and Ultra violet photo electron Spectroscopy (UPS. CuO thin films show a significant band bending downwards (due to higher hole concentration than Cu2O thin films.

  3. Microstructural, optical and electrical properties of Cl-doped CdTe single crystals

    Directory of Open Access Journals (Sweden)

    Choi Hyojeong

    2016-09-01

    Full Text Available Microstructural, optical and electrical properties of Cl-doped CdTe crystals grown by the low pressure Bridgman (LPB method were investigated for four different doping concentrations (unintentionally doped, 4.97 × 1019 cm−3, 9.94 × 1019 cm−3 and 1.99 × 1020 cm−3 and three different locations within the ingots (namely, samples from top, middle and bottom positions in the order of the distance from the tip of the ingot. It was shown that Cl dopant suppressed the unwanted secondary (5 1 1 crystalline orientation. Also, the average size and surface coverage of Te inclusions decreased with an increase in Cl doping concentration. Spectroscopic ellipsometry measurements showed that the optical quality of the Cl-doped CdTe single crystals was enhanced. The resistivity of the CdTe sample doped with Cl at the 1.99 × 1020 cm−3 was above 1010 Ω.cm.

  4. Properties of optically selected BL Lacertae candidates from the SDSS

    Science.gov (United States)

    Kügler, S. D.; Nilsson, K.; Heidt, J.; Esser, J.; Schultz, T.

    2014-09-01

    Context. Deep optical surveys open the avenue for finding large numbers of BL Lac objects that are hard to identify because they lack the unique properties classifying them as such. While radio or X-ray surveys typically reveal dozens of sources, recent compilations based on optical criteria alone have increased the number of BL Lac candidates considerably. However, these compilations are subject to biases and may contain a substantial number of contaminating sources. Aims: In this paper we extend our analysis of 182 optically selected BL Lac object candidates from the SDSS with respect to an earlier study. The main goal is to determine the number of bona fide BL Lac objects in this sample. Methods: We examine their variability characteristics, determine their broad-band radio-UV spectral energy distributions (SEDs), and search for the presence of a host galaxy. In addition we present new optical spectra for 27 targets with improved signal-to-noise ratio with respect to the SDSS spectra. Results: At least 59% of our targets have shown variability between SDSS DR2 and our observations by more than 0.1-0.27 mag depending on the telescope used. A host galaxy was detected in 36% of our targets. The host galaxy type and luminosities are consistent with earlier studies of BL Lac host galaxies. Simple fits to broad-band SEDs for 104 targets of our sample derived synchrotron peak frequencies between 13.5 ≤ log 10(νpeak) ≤ 16 with a peak at log 10 ~ 14.5. Our new optical spectra do not reveal any new redshift for any of our objects. Thus the sample contains a large number of bona fide BL Lac objects and seems to contain a substantial fraction of intermediate-frequency peaked BL Lacs. Based on observations collected with the NTT on La Silla (Chile) operated by the European Southern Observatory under proposal 082.B-0133.Based on observations collected at the Centro Astronómico Hispano Alemán (CAHA), operated jointly by the Max-Planck-Institut für Astronomie and the

  5. Autoindicating optical properties of laccase as the base of an optical biosensor film for phenol determination

    Energy Technology Data Exchange (ETDEWEB)

    Sanz, J.; Marcos, S. de; Galban, J. [University of Zaragoza, Analytical Biosensors Group (GBA), Analytical Chemistry Department, Faculty of Sciences, Zaragoza (Spain)

    2012-08-15

    In the context of sustainable analytical chemistry, phenol has been determined through its enzymatic reaction with laccase. The method has been studied and optimized through the autoindicating optical properties of laccase both by intrinsic molecular absorption and fluorescence. The method shows a linear range from 9.79.10{sup -6} to 7.50.10{sup -4} M with a relative standard deviation of 1.07 %. The molecular absorption methodology has been implemented in a polyacrylamide film for the design of an autoindicating optical sensor. In order to increase the lifetime of the sensor, the reversibility study of the enzymatic reaction has proposed, as a novelty, the regeneration of laccase with an oxidase-type enzyme (glucose oxidase). The lifetime of the sensor film has improved from 15 to 30 measurements. The reaction mechanism has also been studied and confirmed by fluorescence and molecular absorption. The method leads to the determination of phenol in environmental samples. (orig.)

  6. Noble-metal nanoparticles produced with colloidal lithography: fabrication, optical properties and applications

    Energy Technology Data Exchange (ETDEWEB)

    Bocchio, Noelia Laura

    2008-08-15

    In this work, metal nanoparticles produced by nanosphere lithography were studied in terms of their optical properties (in connection to their plasmon resonances), their potential application in sensing platforms - for thin layer sensing and bio-recognition events -, and for a particular case (the nanocrescents), for enhanced spectroscopy studies. The general preparation procedures introduced early in 2005 by Shumaker-Parry et al. to produce metallic nanocrescents were extended to give rise to more complex (isolated) structures, and also, by combining colloidal monolayer fabrication and plasma etching techniques, to arrays of them. The fabrication methods presented in this work were extended not only to new shapes or arrangements of particles, but included also a targeted surface tailoring of the substrates and the structures, using different thiol and silane compounds as linkers for further attachment of, i.e. polyelectrolyte layers, which allow for a controlled tailoring of their nanoenvironment. The optical properties of the nanocrescents were studied with conventional transmission spectroscopy; a simple multipole model was adapted to explain their behaviour qualitatively. In terms of applications, the results on thin film sensing using these particles show that the crescents present an interesting mode-dependent sensitivity and spatial extension. Parallel to this, the penetrations depths were modeled with two simplified schemes, obtaining good agreement with theory. The multiple modes of the particles with their characteristic decay lengths and sensitivities represent a major improvement for particle-sensing platforms compared to previous single resonance systems. The nanocrescents were also used to alter the emission properties of fluorophores placed close to them. In this work, green emitting dyes were placed at controlled distances from the structures and excited using a pulsed laser emitting in the near infrared. The fluorescence signal obtained in this

  7. Non-linear optical techniques and optical properties of condensed molecular systems

    Science.gov (United States)

    Citroni, Margherita

    2013-06-01

    Structure, dynamics, and optical properties of molecular systems can be largely modified by the applied pressure, with remarkable consequences on their chemical stability. Several examples of selective reactions yielding technologically attractive products can be cited, which are particularly efficient when photochemical effects are exploited in conjunction with the structural conditions attained at high density. Non-linear optical techniques are a basic tool to unveil key aspects of the chemical reactivity and dynamic properties of molecules. Their application to high-pressure samples is experimentally challenging, mainly because of the small sample dimensions and of the non-linear effects generated in the anvil materials. In this talk I will present results on the electronic spectra of several aromatic crystals obtained through two-photon induced fluorescence and two-photon excitation profiles measured as a function of pressure (typically up to about 25 GPa), and discuss the relationship between the pressure-induced modifications of the electronic structure and the chemical reactivity at high pressure. I will also present the first successful pump-probe infrared measurement performed as a function of pressure on a condensed molecular system. The system under examination is liquid water, in a sapphire anvil cell, up to 1 GPa along isotherms at 298 and 363 K. These measurements give a new enlightening insight into the dynamical properties of low- and high-density water allowing a definition of the two structures.

  8. Effective optical constants and effective optical properties of ultrathin trilayer structures

    International Nuclear Information System (INIS)

    Haija, A.J.; Larry Freeman, W.; Umbel, Rachel

    2011-01-01

    This work presents an extension of the characteristic effective medium approximation (CEMA) to ultrathin trilayer systems. The extension has been carried out analytically and is supported by corresponding calculations of the effective optical constants of Cu-Au-Cu and Ag-SiO-Ag trilayer systems using the CEMA approximation. This work is in essence a generalization of the characteristic effective medium approximation introduced earlier for ultrathin bilayer structures. This method is used to derive the effective optical constants of a trilayer system, consisting of three thin layers with each constituent layer of thickness much less than the wavelength of the incident radiation. Within this regime a trilayer system is viewed as one effective layer referred to as an effective stack (ES) with well defined effective optical constants, which can be used to calculate the optical properties of the trilayer stack within a specified wavelength range. The CEMA based calculations of the effective optical constants are applied to two trilayer systems with a total of five stacks. Three are Cu-Au-Cu and two are Ag-SiO-Ag stacks. The thicknesses of the parent layers in the Cu-Au-Cu stack range from 3 to 30 nm for Cu and 4 to 40 nm for Au; in the Ag-SiO-Ag stack the constituent layers are 6 nm for Ag, but range from 5 to 10 nm for SiO. This study is for normal or near normal incidence spectroscopy in a wavelength range that extends from visible to near infrared. The agreement between CEMA based ES stack results and those of the standard CMT technique is very satisfactory.

  9. Optical and Physical Properties of ONP Deinked Pulp

    Directory of Open Access Journals (Sweden)

    Iman Akbarpoor

    2012-01-01

    Full Text Available Enzymes are protein molecules with complex structures that accelerate the biochemical reactions. Activity of these chemical compounds is accomplished at limited range of pH, temperature and concentration. In this study, the effects of different concentrations of cellulose enzyme were investigated on deinking of old newsprint. Old newsprint (ONP was repulped at 5% consistency for 10 minutes in disintegrator with total revolution number of 26500. Enzymatic treatments of recycled ONP pulp were done under constant conditions (10% consistency,treatment time of 15 minutes, pH range of 5-5.5 at different cellulose concentrations of 0.025, 0.05, 0.1 and 0.2% (based on oven-dry waste paper. The optical and physical properties of the standard paper (60g/m2 made at different concentrations of cellulose were evaluated in comparison with control pulp (untreated ONP pulp with cellulase. Overall, the results achieved by comparison the optical properties of the paper produced indicated that using cellulase in deinking of ONP led to increase the brightness and the yellowness and decrease the opacity. The brightness was improved to a maximum level of 47.5 ISO %, but the yellowness was decreased to a minimum level of 11.3 ISO %, while the brightness reduced and the yellowness increased at higher concentrations than 0.05% cellulase. The highest opacity of 99.3 ISO % was achieved using 0.1% cellulase even higher than control pulp. The results gained by comparison the physical properties of the paper showed that using cellulase resulted in decrease of paper calliper, air resistance and density and improve the freeness of pulp

  10. Composition dependence of the optical and structural properties of Eu-doped oxyfluoride glasses

    International Nuclear Information System (INIS)

    Zhu, Chaofeng; Wu, Dongqun; Zhang, Yanfei; Zhang, Meimei; Yue, Yuanzheng

    2015-01-01

    Highlights: • Eu doped oxyfluoride glasses for LED applications are studied. • Conversion of Eu 3+ to Eu 2+ is realized in the glasses prepared in air atmosphere. • CaF 2 crystals formed during melt cooling enhance the conversion of Eu 3+ to Eu 2+ . • Content of CaF 2 crystals can be controlled by adjusting base glass compositions. - Abstract: Europium doped oxyfluoride glasses were prepared by the melt quenching method for the light emitting diodes applications. The optical and structural properties of these glasses were studied by means of photoluminescence spectra, Commission Internationale de L’Eclairage chromaticity coordinates, X-ray diffraction, and Fourier transform infrared spectra. We find that the spontaneous reduction of Eu 3+ to Eu 2+ is realized by Eu 3+ ions occupying the sites of Ca 2+ in the glasses prepared in air atmosphere. The Eu 3+ to Eu 2+ conversion efficiency, optical performances and structure of the glasses strongly depend on the base glass compositions. For certain base glass compositions, CaF 2 crystals can form during the melt cooling process, and thereby enhance the conversion from Eu 3+ to Eu 2+ . The formation of CaF 2 crystals can be suppressed by adding CaO, Al 2 O 3 and B 2 O 3 , but enhanced by adding Na 2 O and K 2 O in glass compositions. Finally, we propose a mechanism to explain how the glass structure affects the reduction of Eu ions as well as optical properties of the glasses

  11. Natural Fe3O4 nanoparticles embedded zinc–tellurite glasses: Polarizability and optical properties

    International Nuclear Information System (INIS)

    Widanarto, W.; Sahar, M.R.; Ghoshal, S.K.; Arifin, R.; Rohani, M.S.; Hamzah, K.; Jandra, M.

    2013-01-01

    Modifying the optical behavior of zinc–tellurite glass by embedding magnetic nanoparticles has implication in nanophotonics. A series of zinc–tellurite glasses containing natural Fe 3 O 4 nanoparticles with composition (80 − x)TeO 2 ·xFe 3 O 4 ·20ZnO (0 ≤ x ≤ 2) in mol% are synthesized by melt quenching method and their optical properties are investigated using FTIR and UV–vis–NIR spectroscopies. Lorentz–Lorenz relations are exploited to determine the refractive index, molar refraction and electronic polarizability. The sharp absorption peaks of FTIR spectra show a shift from 667 cm −1 to 671 cm −1 in the presence of nanoparticles that increase the non-bridging oxygen, confirmed by the intensity change of the TeO 3 peak at 752 cm −1 . A new peak around 461 cm −1 is also observed which is attributed to the band characteristic of covalent Fe–O linkages. A decrease in the Urbach energy as much as 0.122 eV and the optical energy band gap with the increase of Fe 3 O 4 concentration (0.5–1.0 mol%) is evidenced. Electronic polarizability of the glasses increases with increasing Fe 3 O 4 nanoparticles concentration up to 1 mol%. Interestingly, the polarizability tends to decrease with the further increase of Fe 3 O 4 concentration at 2 mol%. The role of magnetic nanoparticles in influencing the structural and optical behavior are examined and understood. - Highlights: ► Incorporation of natural Fe 3 O 4 nanoparticles into the zinc–tellurite glass. ► Influence of magnetic nanoparticles in modifying structure and optical properties. ► Enhancement of refraction index and change in electronic polarizability

  12. Effect of temperature on the morphology and electro-optical properties of liquid crystal physical gel

    International Nuclear Information System (INIS)

    Leaw, W.L.; Mamat, C.R.; Triwahyono, S.; Jalil, A.A.; Bidin, N.

    2016-01-01

    Liquid crystal physical gels were (thermally) prepared with cholesteryl stearate as a gelator in nematic liquid crystal, 4-cyano-4′-pentylbiphenyl. The electro-optical performance of liquid crystal physical gels is almost entirely dependent on the gels' inherent morphology. This study involved an empirical investigation of the relationships among all of the gelation temperature, morphology, and electro-optical properties. Besides continuous cooling at room temperature, isothermal cooling was also performed at both 18 and 0 °C, corresponding to near-solid and solid phases of 4-cyano-4′-pentylbiphenyl respectively. Nevertheless, the liquid crystal physical gel was also isothermally rapidly cooled using liquid nitrogen. Polarizing optical microscopy showed that the gel structure became thinner when isothermal cooling was carried out. These thinner gel aggregates then interconnected to form larger liquid crystal domains. Moreover, it was also revealed that the gel networks were randomized. Electron spin resonance results showed that the liquid crystal director orientation was severely randomized in the presence of gel networks. Conversely, isothermal cooling using liquid nitrogen generated a higher liquid crystal director orientation order. The 6.0 wt% cholesteryl stearate/4-cyano-4′-pentylbiphenyl physical gel that was isothermally cooled using liquid nitrogen showed the lowest response time in a twisted nematic mode optical cell. - Graphical abstract: Liquid crystal physical gel was prepared using nematic liquid crystal, 4-cyano-4′-pentylbiphenyl and cholesteryl stearate as gelator. Isothermal cooling at lower temperature produced thinner gel network and larger liquid crystal domain. - Highlights: • 5CB nematic liquid crystal was successfully gelled by cholesteryl stearate gelator. • The morphology of gel network was controlled by different cooling conditions. • Thinner gel network was formed by the rapid cooling using liquid nitrogen. • Enhanced

  13. Effect of temperature on the morphology and electro-optical properties of liquid crystal physical gel

    Energy Technology Data Exchange (ETDEWEB)

    Leaw, W.L. [Department of Chemistry, Faculty of Science, Universiti Teknologi Malaysia, 81310, UTM Johor Bahru, Johor (Malaysia); Mamat, C.R., E-mail: che@kimia.fs.utm.my [Department of Chemistry, Faculty of Science, Universiti Teknologi Malaysia, 81310, UTM Johor Bahru, Johor (Malaysia); Triwahyono, S. [Department of Chemistry, Faculty of Science, Universiti Teknologi Malaysia, 81310, UTM Johor Bahru, Johor (Malaysia); Jalil, A.A. [Department of Chemical Engineering, Faculty of Chemical and Energy Engineering, Universiti Teknologi Malaysia, 81310, UTM Johor Bahru, Johor (Malaysia); Centre of Hydrogen Energy, Institute of Future Energy, Univerisiti Teknologi Malaysia, 81310, UTM Johor Bahru, Johor (Malaysia); Bidin, N. [Department of Physics, Faculty of Science, Universiti Teknologi Malaysia, 81310, UTM Johor Bahru, Johor (Malaysia)

    2016-12-01

    Enhanced electro-optical properties of liquid crystal physical gel were achieved.

  14. Optical properties of (nanometer MCM-41)-(malachite green) composite materials

    International Nuclear Information System (INIS)

    Li Xiaodong; Zhai Qingzhou; Zou Mingqiang

    2010-01-01

    Nanosized materials loaded with organic dyes are of interest with respect to novel optical applications. The optical properties of malachite green (MG) in MCM-41 are considerably influenced by the limited nanoporous channels of nanometer MCM-41. Nanometer MCM-41 was synthesized by tetraethyl orthosilicate (TEOS) as the source of silica and cetyltrimethylammonium bromide (CTMAB) as the template. The liquid-phase grafting method has been employed for incorporation of the malachite green molecules into the channels of nanometer MCM-41. A comparative study has been carried out on the adsorption of the malachite green into modified MCM-41 and unmodified MCM-41. The modified MCM-41 was synthesized using a silylation reagent, trimethychlorosilane (TMSCl), which functionalized the surface of nanometer MCM-41 for proper host-guest interaction. The prepared (nanometer MCM-41)-MG samples have been studied by powder X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, low-temperature nitrogen adsorption-desorption technique at 77 K, Raman spectra and luminescence studies. In the prepared (nanometer MCM-41)-MG composite materials, the frameworks of the host molecular sieve were kept intact and the MG located inside the pores of MCM-41. Compared with the MG, it is found that the prepared composite materials perform a considerable luminescence. The excitation and emission spectra of MG in both modified MCM-41 and unmodified MCM-41 were examined to explore the structural effects on the optical properties of MG. The results of luminescence spectra indicated that the MG molecules existed in monomer form within MCM-41. However, the luminescent intensity of MG incorporated in the modified MCM-41 are higher than that of MG encapsulated in unmodified MCM-41, which may be due to the anchored methyl groups on the channels of the nanometer MCM-41 and the strong host-guest interactions. The steric effect from the pore size of the host materials is significant. Raman

  15. EXCESS OPTICAL ENHANCEMENT OBSERVED WITH ARCONS FOR EARLY CRAB GIANT PULSES

    Energy Technology Data Exchange (ETDEWEB)

    Strader, M. J.; Mazin, B. A.; Spiro Jaeger, G. V.; Gwinn, C. R.; Meeker, S. R.; Szypryt, P.; Van Eyken, J. C.; Marsden, D.; Walter, A. B.; Ulbricht, G. [Department of Physics, University of California, Santa Barbara, CA 93106 (United States); Johnson, M. D. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); O' Brien, K. [Department of Physics, University of Oxford, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH (United Kingdom); Stoughton, C. [Fermilab Center for Particle Astrophysics, Batavia, IL 60510 (United States); Bumble, B. [NASA Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, CA 91125 (United States)

    2013-12-10

    We observe an extraordinary link in the Crab pulsar between the enhancement of an optical pulse and the timing of the corresponding giant radio pulse. At optical through infrared wavelengths, our observations use the high time resolution of ARray Camera for Optical to Near-IR Spectrophotometry, a unique superconducting energy-resolving photon-counting array at the Palomar 200 inch telescope. At radio wavelengths, we observe with the Robert C. Byrd Green Bank Telescope and the Green Bank Ultimate Pulsar Processing Instrument backend. We see an 11.3% ± 2.5% increase in peak optical flux for pulses that have an accompanying giant radio pulse arriving near the peak of the optical main pulse, in contrast to a 3.2% ± 0.5% increase when an accompanying giant radio pulse arrives soon after the optical peak. We also observe that the peak of the optical main pulse is 2.8% ± 0.8% enhanced when there is a giant radio pulse accompanying the optical interpulse. We observe no statistically significant spectral differences between optical pulses accompanied by and not accompanied by giant radio pulses. Our results extend previous observations of optical-radio correlation to the time and spectral domains. Our refined temporal correlation suggests that optical and radio emission are indeed causally linked, and the lack of spectral differences suggests that the same mechanism is responsible for all optical emission.

  16. EXCESS OPTICAL ENHANCEMENT OBSERVED WITH ARCONS FOR EARLY CRAB GIANT PULSES

    International Nuclear Information System (INIS)

    Strader, M. J.; Mazin, B. A.; Spiro Jaeger, G. V.; Gwinn, C. R.; Meeker, S. R.; Szypryt, P.; Van Eyken, J. C.; Marsden, D.; Walter, A. B.; Ulbricht, G.; Johnson, M. D.; O'Brien, K.; Stoughton, C.; Bumble, B.

    2013-01-01

    We observe an extraordinary link in the Crab pulsar between the enhancement of an optical pulse and the timing of the corresponding giant radio pulse. At optical through infrared wavelengths, our observations use the high time resolution of ARray Camera for Optical to Near-IR Spectrophotometry, a unique superconducting energy-resolving photon-counting array at the Palomar 200 inch telescope. At radio wavelengths, we observe with the Robert C. Byrd Green Bank Telescope and the Green Bank Ultimate Pulsar Processing Instrument backend. We see an 11.3% ± 2.5% increase in peak optical flux for pulses that have an accompanying giant radio pulse arriving near the peak of the optical main pulse, in contrast to a 3.2% ± 0.5% increase when an accompanying giant radio pulse arrives soon after the optical peak. We also observe that the peak of the optical main pulse is 2.8% ± 0.8% enhanced when there is a giant radio pulse accompanying the optical interpulse. We observe no statistically significant spectral differences between optical pulses accompanied by and not accompanied by giant radio pulses. Our results extend previous observations of optical-radio correlation to the time and spectral domains. Our refined temporal correlation suggests that optical and radio emission are indeed causally linked, and the lack of spectral differences suggests that the same mechanism is responsible for all optical emission

  17. qF-SSOP: real-time optical property corrected fluorescence imaging

    Science.gov (United States)

    Valdes, Pablo A.; Angelo, Joseph P.; Choi, Hak Soo; Gioux, Sylvain

    2017-01-01

    Fluorescence imaging is well suited to provide image guidance during resections in oncologic and vascular surgery. However, the distorting effects of tissue optical properties on the emitted fluorescence are poorly compensated for on even the most advanced fluorescence image guidance systems, leading to subjective and inaccurate estimates of tissue fluorophore concentrations. Here we present a novel fluorescence imaging technique that performs real-time (i.e., video rate) optical property corrected fluorescence imaging. We perform full field of view simultaneous imaging of tissue optical properties using Single Snapshot of Optical Properties (SSOP) and fluorescence detection. The estimated optical properties are used to correct the emitted fluorescence with a quantitative fluorescence model to provide quantitative fluorescence-Single Snapshot of Optical Properties (qF-SSOP) images with less than 5% error. The technique is rigorous, fast, and quantitative, enabling ease of integration into the surgical workflow with the potential to improve molecular guidance intraoperatively. PMID:28856038

  18. Surface plasmon resonance optical cavity enhanced refractive index sensing

    Czech Academy of Sciences Publication Activity Database

    Giorgini, A.; Avino, S.; Malara, P.; Gagliardi, G.; Casalino, M.; Coppola, G.; Iodice, M.; Adam, Pavel; Chadt, Karel; Homola, Jiří; De Natale, P.

    2013-01-01

    Roč. 38, č. 11 (2013), s. 1951-1953 ISSN 0146-9592 R&D Projects: GA ČR GBP205/12/G118 Institutional support: RVO:67985882 Keywords : Resonators * Surface plasmons * Optical sensing and sensors Subject RIV: BH - Optics, Masers, Lasers Impact factor: 3.179, year: 2013

  19. Invariable optical properties of phosphor-free white light-emitting diode under electrical stress

    International Nuclear Information System (INIS)

    Hao, Long; Hao, Fang; Sheng-Li, Qi; Li-Wen, Sang; Wen-Yu, Cao; Jian, Yan; Jun-Jing, Deng; Zhi-Jian, Yang; Guo-Yi, Zhang

    2010-01-01

    This paper reports that a dual-wavelength white light-emitting diode is fabricated by using a metal-organic chemical vapor deposition method. Through a 200-hours' current stress, the reverse leakage current of this light-emitting diode increases with the aging time, but the optical properties remained unchanged despite the enhanced reverse leakage current. Transmission electron microscopy and cathodeluminescence images show that indium atoms were assembled in and around V-shape pits with various compositions, which can be ascribed to the emitted white light. Evolution of cathodeluminescence intensities under electron irradiation is also performed. Combining cathodeluminescence intensities under electron irradiation and above results, the increase of leakage channels and crystalline quality degradation are realized. Although leakage channels increase with aging, potential fluctuation caused by indium aggregation can effectively avoid the impact of leakage channels. Indium aggregation can be attributed to the mechanism of preventing optical degradation in phosphor-free white light-emitting diode. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  20. Impact of slow-light enhancement on optical propagation in active semiconductor photonic crystal waveguides

    DEFF Research Database (Denmark)

    Chen, Yaohui; de Lasson, Jakob Rosenkrantz; Gregersen, Niels

    2015-01-01

    We derive and validate a set of coupled Bloch wave equations for analyzing the reflection and transmission properties of active semiconductor photonic crystal waveguides. In such devices, slow-light propagation can be used to enhance the material gain per unit length, enabling, for example......, the realization of short optical amplifiers compatible with photonic integration. The coupled wave analysis is compared to numerical approaches based on the Fourier modal method and a frequency domain finite element technique. The presence of material gain leads to the build-up of a backscattered field, which...... is interpreted as distributed feedback effects or reflection at passive-active interfaces, depending on the approach taken. For very large material gain values, the band structure of the waveguide is perturbed, and deviations from the simple coupled Bloch wave model are found....

  1. Electronic and Optical Properties of Twisted Bilayer Graphene

    Science.gov (United States)

    Huang, Shengqiang

    The ability to isolate single atomic layers of van der Waals materials has led to renewed interest in the electronic and optical properties of these materials as they can be fundamentally different at the monolayer limit. Moreover, these 2D crystals can be assembled together layer by layer, with controllable sequence and orientation, to form artificial materials that exhibit new features that are not found in monolayers nor bulk. Twisted bilayer graphene is one such prototype system formed by two monolayer graphene layers placed on top of each other with a twist angle between their lattices, whose electronic band structure depends on the twist angle. This thesis presents the efforts to explore the electronic and optical properties of twisted bilayer graphene by Raman spectroscopy and scanning tunneling microscopy measurements. We first synthesize twisted bilayer graphene with various twist angles via chemical vapor deposition. Using a combination of scanning tunneling microscopy and Raman spectroscopy, the twist angles are determined. The strength of the Raman G peak is sensitive to the electronic band structure of twisted bilayer graphene and therefore we use this peak to monitor changes upon doping. Our results demonstrate the ability to modify the electronic and optical properties of twisted bilayer graphene with doping. We also fabricate twisted bilayer graphene by controllable stacking of two graphene monolayers with a dry transfer technique. For twist angles smaller than one degree, many body interactions play an important role. It requires eight electrons per moire unit cell to fill up each band instead of four electrons in the case of a larger twist angle. For twist angles smaller than 0.4 degree, a network of domain walls separating AB and BA stacking regions forms, which are predicted to host topologically protected helical states. Using scanning tunneling microscopy and spectroscopy, these states are confirmed to appear on the domain walls when inversion

  2. Tunable Bandgap and Optical Properties of Black Phosphorene Nanotubes

    Directory of Open Access Journals (Sweden)

    Chunmei Li

    2018-02-01

    Full Text Available Black phosphorus (BP, a new two-dimensional material, has been the focus of scientists’ attention. BP nanotubes have potential in the field of optoelectronics due to their low-dimensional effects. In this work, the bending strain energy, electronic structure, and optical properties of BP nanotubes were investigated by using the first-principles method based on density functional theory. The results show that these properties are closely related to the rolling direction and radius of the BP nanotube. All the calculated BP nanotube properties show direct bandgaps, and the BP nanotubes with the same rolling direction express a monotone increasing trend in the value of bandgap with a decrease in radius, which is a stacking effect of the compression strain on the inner atoms and the tension strain on the outer atoms. The bending strain energy of the zigzag phosphorene nanotubes (zPNTs is higher than that of armchair phosphorene nanotubes (aPNT with the same radius of curvature due to the anisotropy of the BP’s structure. The imaginary part of the dielectric function, the absorption range, reflectivity, and the imaginary part of the refractive index of aPNTs have a wider range than those of zPNTs, with higher values overall. As a result, tunable BP nanotubes are suitable for optoelectronic devices, such as lasers and diodes, which function in the infrared and ultra-violet regions, and for solar cells and photocatalysis.

  3. Optical properties (bidirectional reflectance distribution function) of shot fabric.

    Science.gov (United States)

    Lu, R; Koenderink, J J; Kappers, A M

    2000-11-01

    To study the optical properties of materials, one needs a complete set of the angular distribution functions of surface scattering from the materials. Here we present a convenient method for collecting a large set of bidirectional reflectance distribution function (BRDF) samples in the hemispherical scattering space. Material samples are wrapped around a right-circular cylinder and irradiated by a parallel light source, and the scattered radiance is collected by a digital camera. We tilted the cylinder around its center to collect the BRDF samples outside the plane of incidence. This method can be used with materials that have isotropic and anisotropic scattering properties. We demonstrate this method in a detailed investigation of shot fabrics. The warps and the fillings of shot fabrics are dyed different colors so that the fabric appears to change color at different viewing angles. These color-changing characteristics are found to be related to the physical and geometrical structure of shot fabric. Our study reveals that the color-changing property of shot fabrics is due mainly to an occlusion effect.

  4. ITO films with enhanced electrical properties deposited on unheated ZnO-coated polymer substrates

    International Nuclear Information System (INIS)

    Nunes de Carvalho, C.; Lavareda, G.; Fortunato, E.; Alves, H.; Goncalves, A.; Varela, J.; Nascimento, R.; Amaral, A.

    2005-01-01

    Indium tin oxide (ITO) films were deposited by radio frequency (rf)-plasma enhanced reactive thermal evaporation (rf-PERTE) at room temperature on intrinsic ZnO/polymer substrates to enhance their electrical and structural properties. The polymer substrate used is polyethylene terephthalate (PET). The thickness of the ZnO films varied in the range 50-150 nm. The average thickness of the ITO films is of about 170 nm. Results show that ITO deposited on bare PET substrates exhibit: an average visible transmittance of about 85% and an electrical resistivity of 5.6 x 10 -2 Ω cm. ITO on ZnO/PET substrates show the optical quality practically preserved and the resistivity decreased to a minimum value of 1.9x10 -3 Ω cm for ZnO layers 125 nm thick. The electrical properties of ITO on ZnO/PET are largely improved by the increase in carrier mobility

  5. A comparative study of the flow enhancing properties of bentonite ...

    African Journals Online (AJOL)

    A comparative study of granule flow enhancing property of bentonite, magnesium stearate, talc and microcrystalline cellulose (MCC) was undertaken. Bentonite was processed into fine powder. A 10 %w/w of starch granules was prepared and separated into different sizes (˂180, 180-500, 500-710 and 710-850 μm).

  6. Enhanced photocatalytic properties in well-ordered mesoporous WO3

    KAUST Repository

    Li, Li; Krissanasaeranee, Methira; Pattinson, Sebastian W.; Stefik, Morgan; Wiesner, Ulrich; Steiner, Ullrich; Eder, Dominik

    2010-01-01

    We used polyisoprene-block-ethyleneoxide copolymers as structure-directing agents to synthesise well-ordered and highly-crystalline mesoporous WO 3 architectures that possess improved photocatalytic properties due to enhanced dye-adsorption in absence of diffusion limitation. © 2010 The Royal Society of Chemistry.

  7. Effect of Etching on the Optical, Morphological Properties of Ag Thin Films for SERS Active Substrates

    Directory of Open Access Journals (Sweden)

    Desapogu Rajesh

    2013-01-01

    Full Text Available Structural, optical, and morphological properties of Ag thin films before and after etching were investigated by using X-ray diffraction, UV-Vis spectrophotometer, and field emission scanning electron microscopy (FESEM. The HNO3 roughened Ag thin films exhibit excellent enhancement features and better stability than pure Ag thin films. Further, the Ag nanostructures are covered with Rhodamine 6G (Rh6G and then tested with surface enhanced raman spectroscopy (SERS for active substrates. Etched Ag films were found to exhibit a strong SERS effect and excellent thermal stability. Hence, the present method is found to be useful in the development of plasmon-based analytical devices, especially SERS-based biosensors.

  8. Enhancement in magnetic properties of magnesium substituted bismuth ferrite nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Jianlong; Xie, Dan, E-mail: xiedan@mail.tsinghua.edu.cn, E-mail: RenTL@mail.tsinghua.edu.cn; Teng, Changjiu; Zhang, Xiaowen; Zhang, Cheng; Sun, Yilin; Ren, Tian-Ling, E-mail: xiedan@mail.tsinghua.edu.cn, E-mail: RenTL@mail.tsinghua.edu.cn [Institute of Microelectronics, Tsinghua National Laboratory for Information Science and Technology (TNList), Tsinghua University, Beijing 100084 (China); Zeng, Min; Gao, Xingsen [Institute for Advanced Materials and Laboratory of Quantum Engineering and Quantum Materials, South China Normal University, Guangzhou 510006 (China); Zhao, Yonggang [Department of Physics and State Key Laboratory of Low-Dimensional Quantum Physics, Tsinghua University, Beijing 100084 (China)

    2015-06-14

    We report a potential way to effectively improve the magnetic properties of BiFeO{sub 3} (BFO) nanoparticles through Mg{sup 2+} ion substitution at the Fe-sites of BFO lattice. The high purity and structural changes induced by Mg doping are confirmed by X-ray powder diffractometer and Raman spectra. Enhanced magnetic properties are observed in Mg substituted samples, which simultaneously exhibit ferromagnetic and superparamagnetic properties at room temperature. A physical model is proposed to support the observed ferromagnetism of Mg doped samples, and the superparamagnetic properties are revealed by the temperature dependent magnetization measurements. The improved magnetic properties and soft nature obtained by Mg doping in BFO nanoparticles demonstrate the possibility of BFO nanoparticles to practical applications.

  9. Effect of dextran-induced changes in refractive index and aggregation on optical properties of whole blood

    International Nuclear Information System (INIS)

    Xu Xiangqun; Wang, Ruikang K; Elder, James B; Tuchin, Valery V

    2003-01-01

    The purpose of the present study is to investigate systematically the mechanisms of alterations in the optical properties of whole blood immersed in the biocompatible agent dextran, and to define the optimal concentration of dextrans required for blood optical clearing in order to enhance the capability of light penetration depth for optical imaging applications. In the experiments, dextrans with different molecular weights and various concentrations were employed and investigated by the use of the optical coherence tomography technique. Changes in light attenuation, refractive index and aggregation properties of blood immersed in dextrans were studied. It was concluded from the results that the mechanisms for blood optical clearing are characteristic of the types of dextrans employed, their concentrations and the application stages. Among the substances applied, Dx500 at a concentration at 0.5 g dl -1 gives the best result in improving light penetration depth through the blood. The increase of light transmission at the beginning of the addition of dextrans is mainly attributed to refractive index matching between the scattering centres and the ground matter. Thereafter, the transmission change is probably due to a dextran-induced aggregation-disaggregation effect. Overall, light scattering in the blood could be effectively reduced by the application of dextrans. It represents a promising approach to increasing the imaging depth for in vivo optical imaging of biological tissue, for example optical coherence tomography

  10. Nonclassical properties of a contradirectional nonlinear optical coupler

    Energy Technology Data Exchange (ETDEWEB)

    Thapliyal, Kishore [Jaypee Institute of Information Technology, A-10, Sector-62, Noida, UP-201307 (India); Pathak, Anirban, E-mail: anirban.pathak@gmail.com [Jaypee Institute of Information Technology, A-10, Sector-62, Noida, UP-201307 (India); RCPTM, Joint Laboratory of Optics of Palacky University and Institute of Physics of Academy of Science of the Czech Republic, Faculty of Science, Palacky University, 17. listopadu 12, 771 46 Olomouc (Czech Republic); Sen, Biswajit [Department of Physics, Vidyasagar Teachers' Training College, Midnapore 721101 (India); Perřina, Jan [RCPTM, Joint Laboratory of Optics of Palacky University and Institute of Physics of Academy of Science of the Czech Republic, Faculty of Science, Palacky University, 17. listopadu 12, 771 46 Olomouc (Czech Republic); Department of Optics, Palacky University, 17. listopadu 12, 771 46 Olomouc (Czech Republic)

    2014-10-24

    We investigate the nonclassical properties of output fields propagated through a contradirectional asymmetric nonlinear optical coupler consisting of a linear waveguide and a nonlinear (quadratic) waveguide operated by second harmonic generation. In contrast to the earlier results, all the initial fields are considered weak and a completely quantum-mechanical model is used here to describe the system. Perturbative solutions of Heisenberg's equations of motion for various field modes are obtained using Sen–Mandal technique. Obtained solutions are subsequently used to show the existence of single-mode and intermodal squeezing, single-mode and intermodal antibunching, two-mode and multi-mode entanglement in the output of contradirectional asymmetric nonlinear optical coupler. Further, existence of higher order nonclassicality is also established by showing the existence of higher order antibunching, higher order squeezing and higher order entanglement. Variation of observed nonclassical characters with different coupling constants and phase mismatch is discussed. - Highlights: • Nonclassicalities in fields propagating through a directional coupler is studied. • Completely quantum-mechanical description of the coupler is provided. • Analytic solutions of Heisenberg equations of motion for various modes are obtained. • Existence of lower order and higher order entanglement is shown. • Variation of nonclassicalities with phase-mismatch and coupling constants is studied.

  11. Optical properties of anisotropic 3D nanoparticles arrays

    Science.gov (United States)

    Santiago, E. Y.; Esquivel-Sirvent, R.

    2017-07-01

    The optical properties of 3D periodic arrays of spheroidal Au nanoparticles are calculated using a Bruggeman effective medium approximation. The optical response of the supra-crystal depends on the volume fraction of the nanoparticles and their aspect or size ratio (major/minor axis). All the nanoparticles have the same orientation, and this defines an anisotropic dielectric function of the crystal. As a function of the filling fraction, while keeping the size ratio fixed, the maximum in the extinction spectra along the major and minor axes does not show a significant change. However, for a fixed filling fraction, varying the aspect ratio of the particles induces a shift of several hundred of nanometers in the maximum of the extinction spectra along the major axis and almost no changes along the minor axis. Depending on the aspect ratio and the filling fraction, we show that the supra-crystal has three regimes with different values of an effective plasma frequency. Contribution to the Focus Issue Self-assemblies of Inorganic and Organic Nanomaterials edited by Marie-Paule Pileni.

  12. Optical properties of electron-irradiated gallium phosphide

    International Nuclear Information System (INIS)

    Brailovskii, E.Yu.; Grigoryan, N.E.; Eritsyan, G.N.

    1980-01-01

    Results of optical absorption and photoconductivity measurements in the 0.1 to 2.4 eV range of GaP crystals irradiated with 7.5 and 50 MeV electrons are presented. The absorption of irradiated crystals near the edge can be represented by two exponential regions. In the free carrier absorption region one can observe as a result of irradiation a decrease of the power index p in the dependence α proportional to lambdap. Photoconductivity with long-time relaxation takes place in the spectral interval where the additional absorption is observed. The quenching of residual conductivity can be observed at hν=1.0eV. Variations in absorption and photoconductivity are attributed to the 'tails' of density states near the zone edges arising at introduction of both point defects and disordered regions. At hν=2.1eV one can observe a resonance band which is attributed to intra-centre transitions on point defects. A recovery of the optical properties of GaP at annealing is studied. In heavily irradiated GaP crystals point defects can form gatherings which display themselves as disordered regions. (author)

  13. Optical properties of bcc d-transition metals

    Energy Technology Data Exchange (ETDEWEB)

    Kirillova, M M; Nomerovannaya, L V [AN SSSR, Sverdlovsk. Inst. Fiziki Metallov

    1978-04-01

    The optical properties of a niobium monocrystal in the spectral range of h..nu..=4.66 - 0.069 eV have been studied using the polarimetry method. The obtained results have been discussed on the basis of the zone calculations of the density of electron states for Nb and other isostructural metals of the 5 and 6 groups (Y, Ta, Cr, Mo, W). The existence of an intense low energy interband absorption in niobium in the range of h..nu..<0.1 eV is shown experimentally. The influence of the gapless and low-energy interzone transitions on the evaluations of the plasma and relaxation frequencies of conductivity electrons of d metals is discussed.

  14. Scaling properties of optical reflectance from quasi-periodic superlattices

    International Nuclear Information System (INIS)

    Wu Xiang; Yao Hesheng; Feng Weiguo

    1991-08-01

    The scaling properties of the optical reflectance from two types of quasi-periodic metal-insulator superlattices, one with the structure of Cantor bars and the other with the structure of Cantorian-Fibonaccian train, have been studied for the region of s-polarized soft x-rays and extreme ultraviolet. By using the hydrodynamic model of electron dynamics and transfer-matrix method, and be taking into account retardation effects, we have presented the formalism of the reflectivity for the superlattices. From our numerical results, we found that the reflection spectra of the quasi-superlattices have a rich structure of self-similarity. The interesting scaling indices, which are related to the fractal dimensions, of the spectra are also discussed for the two kinds of the quasi-superlattices. (author). 10 refs, 7 figs

  15. Morphological and optical properties of silicon thin films by PLD

    International Nuclear Information System (INIS)

    Ayouchi, R.; Schwarz, R.; Melo, L.V.; Ramalho, R.; Alves, E.; Marques, C.P.; Santos, L.; Almeida, R.; Conde, O.

    2009-01-01

    Silicon thin films have been prepared on sapphire substrates by pulsed laser deposition (PLD) technique. The films were deposited in vacuum from a silicon target at a base pressure of 10 -6 mbar in the temperature range from 400 to 800 deg. C. A Q-switched Nd:YAG laser (1064 nm, 5 ns duration, 10 Hz) at a constant energy density of 2 J x cm -2 has been used. The influence of the substrate temperature on the structural, morphological and optical properties of the Si thin films was investigated. Spectral ellipsometry and atomic force microscopy (AFM) were used to study the thickness and the surface roughness of the deposited films. Surface roughness values measured by AFM and ellipsometry show the same tendency of increasing roughness with increased deposition temperature

  16. Optical properties of T-centers under gamma irradiation

    CERN Document Server

    Polosan, S; Dragusin, M; Topa, V

    2003-01-01

    Electrolytic coloring of KCl:Pb crystals, leads to formation of negative metal ions with intense emission in the infrared region. These new color centers were named T centers; their most probable configuration could be Pb sub 2 sup 2 sup - , due to the lack of EPR or DCM signals. In order to destroy these structures, the crystals were irradiated with gamma-rays at high doses. The results were the detachment of the electrons from T centers and the appearance of Pb sup 2 sup + - ions. The possibility cannot be excluded of the existence of Pb sup + and Pb sup 0 centers in the samples, because these centers do not exhibit any optical properties on this spectral region. (authors)

  17. Optical properties of nonimaging concentrators with corrugated reflectors

    Science.gov (United States)

    Roennelid, Mats; Perers, Bengt; Karlsson, Bjorn

    1994-09-01

    A ray tracing study has been performed on the optical properties of cylindrical nonimaging concentrators with linear corrugated reflectors. The corrugations are assumed to be V-formed and to have an extension parallel to the meridian plane of the concentrators. It is shown that the acceptance angle for radiation incident in the meridian plane can be increased for moderate corrugations. This increased acceptance is balanced by a decreased acceptance of radiation from other directions. Calculations of angular acceptance for a 2X compound parabolic concentrator is presented. It is shown that the annual irradiation on a solar collector with booster reflector can be increased if corrugated reflectors are used instead of smooth reflectors.

  18. Inherent optical properties of the coccolithophore: Emiliania huxleyi.

    Science.gov (United States)

    Zhai, Peng-Wang; Hu, Yongxiang; Trepte, Charles R; Winker, David M; Josset, Damien B; Lucker, Patricia L; Kattawar, George W

    2013-07-29

    A realistic nonspherical model for Emiliania huxleyi (EHUX) is built, based on electron micrographs of coccolithophore cells. The Inherent Optical Properties (IOP) of the EHUX are then calculated numerically by using the discrete dipole approximation. The coccolithophore model includes a near-spherical core with the refractive index of 1.04 + m(i)j, and a carbonate shell formed by smaller coccoliths with refractive index of 1.2 + m(i)j, where m(i) = 0 or 0.01 and j(2) = -1. The reported IOP are the Mueller scattering matrix, backscattering probability, and depolarization ratio. Our calculation shows that the Mueller matrices of coccolithophores show different angular dependence from those of coccoliths.

  19. Optical properties of metallic Fibonacci quasi-superlattice

    International Nuclear Information System (INIS)

    Feng Weiguo; Liu Nianhua; Wu Xiang

    1990-06-01

    Within the approximation of hydrodynamic model, the optical properties of the metallic Fibonacci quasi-superlattice have been studied for the region of s-polarized soft x-rays and extreme ultraviolet. By using the transfer-matrix method and taking account of damping effects, we have discussed the electromagnetic normal modes for the quasisuperlattice in the rational approximation. The related dispersion curves explain the reflection spectra well, and we found that similar to the reflectivities, both real part and imagine part of the dispersion relation pattern has a rich structure of self-similarity. With the increasing of the generation number, the electromagnetic modes all become critical. (author). 13 refs, 3 figs

  20. Optical properties of photopolymerizable nanocomposites containing nanosized molecular sieves

    International Nuclear Information System (INIS)

    Naydenova, I; Leite, E; Babeva, Tz; Pandey, N; Baron, T; Martin, S; Toal, V; Yovcheva, T; Sainov, S; Mintova, S

    2011-01-01

    Acrylamide-based photopolymerizable nanocomposites containing three types of nanosized crystals with controlled microporosity, Silicalite-1 (MFI-structure), AlPO-18 (AEI-structure) and Beta (BEA-structure) are studied. The influence of the porous nanoparticles on the average refractive index, optical scattering and holographic recording properties of the nanocomposite are characterized. The redistribution of nanoparticles as a result of the holographic recording in the layers is investigated by Raman spectroscopy. It is observed that in all three nanocomposites the nanoparticles are redistributed according to the illuminating light pattern. This redistribution improves the refractive index modulation only in the case of the MFI nanoparticles, while no improvement is observed in AEI and BEA doped layers. The results can be explained by the hydrophobic/hydrophilic nature of the nanoparticles and their interactions, or absence of interactions, with the host photopolymer

  1. Tunable Optical Properties of Metal Nanoparticle Sol-Gel Composites

    Science.gov (United States)

    Smith, David D.; Snow, Lanee A.; Sibille, Laurent; Ignont, Erica

    2001-01-01

    We demonstrate that the linear and non-linear optical properties of sol-gels containing metal nanoparticles are highly tunable with porosity. Moreover, we extend the technique of immersion spectroscopy to inhomogeneous hosts, such as aerogels, and determine rigorous bounds for the average fractional composition of each component, i.e., the porosity of the aerogel, or equivalently, for these materials, the catalytic dispersion. Sol-gels containing noble metal nanoparticles were fabricated and a significant blue-shift in the surface plasmon resonance (SPR) was observed upon formation of an aerogel, as a result of the decrease in the dielectric constant of the matrix upon supercritical extraction of the solvent. However, as a result of chemical interface damping and aggregation this blue-shift does not strictly obey standard effective medium theories. Mitigation of these complications is achieved by avoiding the use of alcohol and by annealing the samples in a reducing atmosphere.

  2. Effect of dielectric confinement on optical properties of colloidal nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Rodina, A. V., E-mail: anna.rodina@mail.ioffe.ru [Russian Academy of Sciences, Ioffe Physicotechnical Institute (Russian Federation); Efros, Al. L., E-mail: efros@nrl.navy.mil [Naval Research Laboratory (United States)

    2016-03-15

    We review the effects caused by a large difference in the dielectric constants of a semiconductor and its surrounding in colloidal semiconductor nanostructures (NSs) with various shapes, e.g., nanocrystals, nanorods, and nanoplatelets. The difference increases the electron–hole interaction and consequently the exciton binding energy and its oscillator transition strength. On the other hand, this difference reduces the electric field of a photon penetrating the NS (the phenomenon is called the local field effect) and reduces the photon coupling to an exciton. We show that the polarization properties of the individual colloidal NSs as well as of their randomly oriented ensemble are determined both by the anisotropy of the local field effect and by the symmetry of the exciton states participating in optical transitions. The calculations explain the temperature and time dependences of the degree of linear polarization measured in an ensemble of CdSe nanocrystals.

  3. Reduced reabsorption and enhanced propagation induced by large Stokes shift in quantum dot-filled optical fiber

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Hua; Zhang, Yu, E-mail: yuzhang@jlu.edu.cn; Lu, Min; Liu, Wenyan [Jilin University, State Key Laboratory on Integrated Optoelectronics and College of Electronic Science and Engineering (China); Xu, Jian [The Pennsylvania State University, Department of Engineering Science and Mechanics (United States); Yu, William W., E-mail: wyu6000@gmail.com [Jilin University, State Key Laboratory on Integrated Optoelectronics and College of Electronic Science and Engineering (China)

    2016-07-15

    With tunable emission wavelength, high photoluminescence quantum yield, and broad absorption, colloidal quantum dots are attractive for the application in optical fiber as dopants. However, most of the quantum dots have a large overlap between their absorption and photoluminescence spectra, resulting in reabsorption loss which hinders the realization of long-distance waveguides. Therefore, ZnCuInS/ZnSe/ZnS quantum dots with large Stokes shift were proposed to fabricate a liquid-core optical fiber in this work. In this work, ZnCuInS/ZnSe/ZnS QDs with an average size of 3.3 nm were synthesized and the optical properties of the QD-filled fiber were also investigated as a function of fiber length and doping concentration. Compared to the control sample filled with CdSe/CdS/ZnS quantum dots, the ZnCuInS/ZnSe/ZnS quantum dot-based waveguides showed reduced reabsorption and enhanced signal propagation, which demonstrates great potential of large Stokes-shift quantum dots in optical waveguide devices.Graphical AbstractA reduced reabsorption and enhanced propagation of ZnCuInS/ZnSe/ZnS QDs-doped liquid-core optical fiber was achieved due to the large Stokes shift.

  4. Optical Properties and Aging of Light Absorbing Secondary Organic Aerosol

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Jiumeng; Lin, Peng; Laskin, Alexander; Laskin, Julia; Kathmann, Shawn M.; Wise, Matthew E.; Caylor, Ryan; Imholt, Felisha; Selimovic, Vanessa; Shilling, John E.

    2016-10-14

    The light-absorbing organic aerosol (OA), commonly referred to as “brown carbon (BrC)”, has attracted considerable attention in recent years because of its potential to affect atmospheric radiation balance, especially in the ultraviolet region and thus impact photochemical processes. A growing amount of data has indicated that BrC is prevalent in the atmosphere, which has motivated numerous laboratory and field studies; however, our understanding of the relationship between the chemical composition and optical properties of BrC remains limited. We conducted chamber experiments to investigate the effect of various VOC precursors, NOx concentrations, photolysis time and relative humidity (RH) on the light absorption of selected secondary organic aerosols (SOA). Light absorption of chamber generated SOA samples, especially aromatic SOA, was found to increase with NOx concentration, at moderate RH, and for the shortest photolysis aging times. The highest mass absorption coefficients (MAC) value is observed from toluene SOA products formed under high NOx conditions at moderate RH, in which nitro-aromatics were previously identified as the major light absorbing compounds. BrC light absorption is observed to decrease with photolysis time, correlated with a decline of the organonitrate fraction of SOA. SOA formed from mixtures of aromatics and isoprene absorb less visible and UV light than SOA formed from aromatic precursors alone on a mass basis. However, the mixed-SOA absorption was underestimated when optical properties were predicted using a two-product SOA formation model, as done in many current climate models. Further investigation, including analysis on detailed mechanisms, are required to explain the discrepancy.

  5. Spectral optical properties of selected photosynthetic microalgae producing biofuels

    International Nuclear Information System (INIS)

    Lee, Euntaek; Heng, Ri-Liang; Pilon, Laurent

    2013-01-01

    This paper presents the spectral complex index of refraction of biofuel producing photosynthetic microalgae between 400 and 750 nm. They were retrieved from their experimentally measured average absorption and scattering cross-sections. The microalgae were treated as homogeneous polydisperse spheres with equivalent diameter such that their surface area was identical to that of their actual spheroidal shape. An inverse method was developed combining Lorentz–Mie theory as the forward method and genetic algorithm. The unicellular green algae Chlamydomonas reinhardtii strain CC125 and its truncated chlorophyll antenna transformants tla1, tlaX, and tla1-CW + as well as Botryococcus braunii, Chlorella sp., and Chlorococcum littorale were investigated. These species were selected for their ability to produce either hydrogen gas or lipids for liquid fuel production. Their retrieved real and imaginary parts of the complex index of refraction were continuous functions of wavelength with absorption peaks corresponding to those of in vivo Chlorophylls a and b. The T-matrix method was also found to accurately predict the experimental measurements by treating the microalgae as axisymmetric spheroids with the experimentally measured major and minor diameter distributions and the retrieved spectral complex index of refraction. Finally, pigment mass fractions were also estimated from the retrieved absorption index. The method and/or the reported optical properties can be used in various applications from ocean remote sensing, carbon cycle study, as well as photobiological carbon dioxide mitigation and biofuel production. -- Highlights: ► Retrieval of optical properties from average absorption and scattering cross-sections. ► Inverse method based on Lorentz–Mie theory and genetic algorithm. ► Refraction and absorption indices of selected microalgae between 400 and 750 nm. ► Determination of pigment concentrations from absorption index. ► Good agreement between T

  6. Optical properties of CAD-CAM ceramic systems.

    Science.gov (United States)

    Della Bona, Alvaro; Nogueira, Audrea D; Pecho, Oscar E

    2014-09-01

    To evaluate the direct transmittance (T%), translucency, opacity and opalescence of CAD-CAM ceramic systems and the correlation between the translucency parameter (TP) and the contrast ratio (CR). Specimens of shades A1, A2 and A3 (n=5) were fabricated from CAD-CAM ceramic blocks (IPS e.max(®) CAD HT and LT, IPS Empress(®) CAD HT and LT, Paradigm™ C, and VITABLOCS(®) Mark II) and polished to 1.0±0.01mm in thickness. A spectrophotometer (Lambda 20) was used to measure T% on the wavelength range of 400-780nm. Another spectrophotometer (VITA Easyshade(®) Advance) was used to measure the CIE L(*)a(*)b(*) coordinates and the reflectance value (Y) of samples on white and black backgrounds. TP, CR and the opalescence parameter (OP) were calculated. Data were statistically analysed using VAF (variance accounting for) coefficient with Cauchy-Schwarz inequality, one-way ANOVA, Tukey's test, Bonferroni correction and Pearson's correlation. T% of some ceramic systems is dependent on the wavelength. The spectral behaviour showed a slight and constant increase in T% up to approximately 550nm, then some ceramics changed the behaviour as the wavelength gets longer. TP and CR values ranged, respectively, from 16.79 to 21.69 and from 0.52 to 0.64 (r(2)=-0.97). OP values ranged from 3.01 to 7.64. The microstructure of CAD-CAM ceramic systems influenced the optical properties. TP and CR showed a strong correlation for all ceramic systems evaluated. Yet, all ceramics showed some degree of light transmittance. In addition to shade, this study showed that other optical properties influence on the natural appearance of dental ceramics. Copyright © 2014 Elsevier Ltd. All rights reserved.

  7. Role of oxygen on the optical properties of borate glass doped with ZnO

    International Nuclear Information System (INIS)

    Abdel-Baki, Manal; El-Diasty, Fouad

    2011-01-01

    Lithium tungsten borate glass (0.56-x)B 2 O 3 -0.4Li 2 O-xZnO-0.04WO 3 (0≤x≤0.1 mol%) is prepared by the melt quenching technique for photonic applications. Small relative values of ZnO are used to improve the glass optical dispersion and to probe as well the role of oxygen electronic polarizability on its optical characteristics. The spectroscopic properties of the glass are determined in a wide spectrum range (200-2500 nm) using a Fresnel-based spectrophotometric technique. Based on the Lorentz-Lorenz theory, as ZnO content increases on the expense of B 2 O 3 the glass molar polarizability increased due to an enhanced unshared oxide ion 2p electron density, which increases ionicity of the chemical bonds of glass. The role of oxide ion polarizability is explained in accordance with advanced measures and theories such as optical basicity, O 1s binding energy, the outer most cation binding energy in Yamashita-Kurosawa's interionic interaction parameter and Sun's average single bond strength. FT-IR measurements confirm an increase in bridging oxygen bonds, as a result of replacement of ZnO by B 2 O 3 , which increase the UV glass transmission window and transmittance. - Graphical abstract: O1s, Yamashita-Kurosawa's parameter and average single bond strength of charge overlapping between electronic shells are used to explain enhanced oxide ion 2p electron density, which increases refractive index of glasses. Highlights: → New borate glass for photonic application is prepared. → The dispersion property of the glass is effectively controlled using small amounts of ZnO. → ZnO is used to probe the glass structure and investigate the role of oxygen on the obtained optical properties of the glasses. → Modern theories are used to explain enhanced unshared oxide ion 2p electron density, which increases ionicity of chemical bonds of the glass.

  8. COFFEE - Coherent Optical System Field Trial for Spectral Efficiency Enhancement

    DEFF Research Database (Denmark)

    Imran, Muhammad; Fresi, Francesco; Rommel, Simon

    2016-01-01

    The scope, aims, and contributions of the COFFEE project for spectral efficiency enhancement and market exposure are presented.......The scope, aims, and contributions of the COFFEE project for spectral efficiency enhancement and market exposure are presented....

  9. Optical Downconverting Nanomaterials for Enhanced Photovoltaic Efficiency, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — For photovoltaic cells used to power space missions, such as those based on silicon, CuInGaSe2, and III-V materials, optical-to-electrical conversion efficiency is...

  10. Graphene derivatives/Fe_3O_4/polymer nanocomposite films: Optical and electrical properties

    International Nuclear Information System (INIS)

    Hatel, Rhizlane; Goumri, Meryem; Ratier, Bernard; Baitoul, Mimouna

    2017-01-01

    This paper reports a simple solution casting method for the preparation of nanocomposite films in which graphene oxide (GO)/Fe_3O_4 nanocomposites are incorporated into poly (vinyl alcohol) (PVA) matrix. The films obtained with different weight percent of GO/Fe_3O_4 (0.5, 0.7 and 1 wt%) are subjected an in situ chemical and thermal reduction in order to explore the evolution and interactions between these components under different treatments and get an insight into on how this can affects the optical and electrical properties of these nanocomposites. Characterization was carried out using, UV–Vis absorption, Photoluminescence, electrical conductivity measurements, Fourier transform infrared spectroscopy (FT-IR) and Raman spectroscopy. Strong covalent functionalization occurs between the polymer and graphene derivatives (GD)/Fe_3O_4 hybrids. The experimental results obtained for our nanocomposites films exhibit significant enhancement in properties highlighted the efficiency of the in situ thermal reduction. The high absorption with strong photoluminescence and electrical conductivity achieved might promote these nanocomposites for opto-electronic devices in near future. - Highlights: • Novel inorganic-organic hybrid flexible films were successfully prepared. • Good interfacial interaction between the graphene/Fe_3O_4 and the hydroxyl-rich PVA. • Optical and electrical properties of Graphene Derivatives/Fe_3O_4/PVA were investigated. • Thermally reduced GO/Fe_3O_4/PVA films show high absorption and strong photoluminescence.

  11. Effect of Nickel sulphate on Growth, Structural, Optical, Mechanical and thermal properties of L-alanine Single Crystals (LANS)

    Science.gov (United States)

    Jothimani, R.; Selvarajan, P.

    2017-08-01

    The nonlinear optical materials find excellent place in frequency conversion, optical telecommunication, image processing, optical computing, and data storage. Due to possessing chiral symmetry and nature of crystallize in noncentro-symmetric space groups, the amino acids are applicable in NLO applications. A transparent nickel sulphate admixtured L-alanine crystal has been developed by solution method. X ray diffraction analysis depicts the orthorhombic crystal system of the sample. NLO efficiency of the sample was found to be highly pronounced compare to KDP. An enhanced linear optical property of the sample shows its suitability for NLO applications. Thermal behaviour of the sample was found by TGA/DTA analysis. Hardness parameters were also found for the sample by microhardness measurements. Laser damage threshold were also measured using Nd: YAG laser.

  12. Resonantly enhanced nonlinear optics in semiconductor quantum wells: An application to sensitive infrared detection

    International Nuclear Information System (INIS)

    Yelin, S.F.; Hemmer, P.R.

    2002-01-01

    A novel class of coherent nonlinear optical phenomena, involving induced transparency in semiconductor quantum wells, is considered in the context of a particular application to sensitive long-wavelength infrared detection. It is shown that the strongest decoherence mechanisms can be suppressed or mitigated, resulting in substantial enhancement of nonlinear optical effects in semiconductor quantum wells

  13. The Effect of Trimethylaluminum Flow Rate on the Structure and Optical Properties of AlInGaN Quaternary Epilayers

    Directory of Open Access Journals (Sweden)

    Dongbo Wang

    2017-03-01

    Full Text Available In this work, a series of quaternary AlxInyGa1−x−yN thin films have been successfully achieved using metal organic chemical vapor deposition (MOCVD method with adjustable trimethylaluminum (TMA flows. Surface morphology and optical properties of AlxInyGa1−x−yN films have been evaluated. The indium segregation effect on the enhancement of UV luminescence emission in AlxInyGa1-x-yN films with increasing TMA flows was investigated. Our results shed some lights on future optical materials design and LED/LD applications.

  14. About the optical properties of oxidized black silicon structures

    Science.gov (United States)

    Pincik, E.; Brunner, R.; Kobayashi, H.; Mikula, M.; Kučera, M.; Švec, P.; Greguš, J.; Vojtek, P.; Zábudlá, Z.; Imamura, K.; Zahoran, M.

    2017-02-01

    The paper deals with the optical and morphological properties of thermally oxidized black silicon (OBSi) nano-crystalline specimens produced by the surface structure chemical transfer method (SSCT). This method can produce a nano-crystalline Si black color layer on c-Si with a range of thickness of ∼50 nm to ∼300 nm by the contact of c-Si immersed in chemical solutions HF + H2O2 with a catalytic mesh. We present and discuss mainly the photoluminescence properties of both polished c-Si and OBSi structures, respectively. The similar photoluminescence (PL) behaviors recorded at liquid helium (6 K) and room temperatures on both polished crystalline Si and OBSi samples, respectively, indicate the similar origin of recorded luminescence light. As the positions of PL maxima of OBSi structures are mainly related to the size of Si nanocrystallites and SiO(x), we therefore suppose that the size of the dominant parts of the luminated OBSi nanostructure is pre-determined by the used polishing Si procedure, and/or the distribution function of the number of formed crystallites on their size is very similar. The blue shift of both PL spectra reaching almost value of 0.40 eV observed after the decrease of the sample temperature to 6 K we relate also with the change of the semiconductor band gap width.

  15. Mechano-optic logic gate controlled by third-order nonlinear optical properties in a rotating ZnO:Au thin film

    International Nuclear Information System (INIS)

    Carrillo-Delgado, C; Torres-Torres, C; García-Merino, J A; García-Gil, C I; Khomenko, A V; Trejo-Valdez, M; Martínez-Gutiérrez, H; Torres-Martínez, R

    2016-01-01

    Measurements of the third-order nonlinear optical properties exhibited by a ZnO thin solid film deposited on a SnO 2 substrate are presented. The samples were prepared by a spray pyrolysis processing route. Scanning electron microscopy analysis and UV–Vis spectroscopy studies were carried out. The picosecond response at 1064 nm was explored by the z-scan technique. A large optical Kerr effect with two-photon absorption was obtained. The inhibition of the nonlinear optical absorption together with a noticeable enhancement in the optical Kerr effect in the sample was achieved by the incorporation of Au nanoparticles into the ZnO film. Additionally, a two-wave mixing configuration at 532 nm was performed and an optical Kerr effect was identified as the main cause of the nanosecond third-order optical nonlinearity. The relaxation time of the photothermal response of the sample was estimated to be about 1 s when the sample was excited by nanosecond single-shots. The rotation of the sample during the nanosecond two-wave mixing experiments was analyzed. It was stated that a non-monotonic relation between rotating frequency and pulse repetition rate governs the thermal contribution to the nonlinear refractive index exhibited by a rotating film. Potential applications for switching photothermal interactions in rotating samples can be contemplated. A rotary logic system dependent on Kerr transmittance in a two-wave mixing experiment was proposed. (paper)

  16. The optical properties of galaxies in the Ophiuchus cluster

    Science.gov (United States)

    Durret, F.; Wakamatsu, K.; Adami, C.; Nagayama, T.; Omega Muleka Mwewa Mwaba, J. M.

    2018-05-01

    Context. Ophiuchus is one of the most massive clusters known, but due to its low Galactic latitude its optical properties remain poorly known. Aims: We investigate the optical properties of Ophiuchus to obtain clues on the formation epoch of this cluster, and compare them to those of the Coma cluster, which is comparable in mass to Ophiuchus but much more dynamically disturbed. Methods: Based on a deep image of the Ophiuchus cluster in the r' band obtained at the Canada France Hawaii Telescope with the MegaCam camera, we have applied an iterative process to subtract the contribution of the numerous stars that, due to the low Galactic latitude of the cluster, pollute the image, and have obtained a photometric catalogue of 2818 galaxies fully complete at r' = 20.5 mag and still 91% complete at r' = 21.5 mag. We use this catalogue to derive the cluster Galaxy Luminosity Function (GLF) for the overall image and for a region (hereafter the "rectangle" region) covering exactly the same physical size as the region in which the GLF of the Coma cluster was previously studied. We then compute density maps based on an adaptive kernel technique, for different magnitude limits, and define three circular regions covering 0.08, 0.08, and 0.06 deg2, respectively, centred on the cluster (C), on northwest (NW) of the cluster, and southeast (SE) of the cluster, in which we compute the GLFs. Results: The GLF fits are much better when a Gaussian is added to the usual Schechter function, to account for the excess of very bright galaxies. Compared to Coma, Ophiuchus shows a strong excess of bright galaxies. Conclusions: The properties of the two nearby very massive clusters Ophiuchus and Coma are quite comparable, though they seem embedded in different large-scale environments. Our interpretation is that Ophiuchus was built up long ago, as confirmed by its relaxed state (see paper I) while Coma is still in the process of forming. The photometric catalogue of Ophiuchus (full Table B.1) is

  17. Froth Image Acquisition and Enhancement on Optical Correction and Retinex Compensation

    Directory of Open Access Journals (Sweden)

    Weixing Wang

    2018-03-01

    Full Text Available To well monitor and optimize the flotation production, a computer vision and image analysis system is used. In such a system, the first important step is to acquire the froth surface images in high quality. Froth imaging quality is hard to control, and the industrial field noise, froth 3D properties, complex textures, and mixed colors can also cause the flotation image to be difficult to segment and process. To acquire high quality images, a new system for image acquisition of the lead flotation is studied. The system constructs the free-form surface lens based on the non-imaging optics theory, which can improve the optical efficiency of the lens and the uniformity of light sources, and can reduce flare effects. For the compensation, an improved MSR (Multi-Scale Retinex adaptive image algorithm is proposed to increase the brightness and intensity contrast for small bubbles, and to enhance texture details and froth weak edges by analyzing the Retinex output characteristics of the shaded area and improving the gain function. Under the condition of the optimal parameters, the image acquisition system can obtain uniform illumination and reduce different noises. Experiments show that the new froth image acquisition system increases Signal/Noise by 14%, contrast by 21%, and image segmentation accuracy by 26% in an image.

  18. Electronic structure and optical properties of prominent phases of T i ...

    Indian Academy of Sciences (India)

    2017-06-19

    Jun 19, 2017 ... ... in excellent agreement with experimental results. Our calculation of optical properties reveals that maximum value of the transmittance in anatase phase of ( T i O 2 ) may be achieved by considering the anisotropic behaviour of the optical spectra in the optical region for transparent conducting application.

  19. Near-field enhanced optical tweezers utilizing femtosecond-laser nanostructured substrates

    Energy Technology Data Exchange (ETDEWEB)

    Kotsifaki, D. G., E-mail: dkotsif@eie.gr; Kandyla, M. [Theoretical and Physical Chemistry Institute, National Hellenic Research Foundation, 48 Vasileos Constantinou Avenue, 11635 Athens (Greece); Lagoudakis, P. G. [Department of Physics and Astronomy, University of Southampton, Southampton SO17 1BJ (United Kingdom)

    2015-11-23

    We present experimental evidence of plasmonic-enhanced optical tweezers, of polystyrene beads in deionized water in the vicinity of metal-coated nanostructures. The optical tweezers operate with a continuous wave near-infrared laser. We employ a Cu/Au bilayer that significantly improves dissipation of heat generated by the trapping laser beam and avoid de-trapping from heat convection currents. We investigate the improvement of the optical trapping force and the effective trapping quality factor, and observe an exponential distance dependence of the trapping force from the nanostructures, indicative of evanescent plasmonic enhancement.

  20. Strain-enhanced optical absorbance of topological insulator films

    DEFF Research Database (Denmark)

    Brems, Mathias Rosdahl; Paaske, Jens; Lunde, Anders Mathias

    2018-01-01

    Topological insulator films are promising materials for optoelectronics due to a strong optical absorption and a thickness-dependent band gap of the topological surface states. They are superior candidates for photodetector applications in the THz-infrared spectrum, with a potential performance...... thickness, the surface-state band gap, and thereby the optical absorption, can be effectively tuned by the application of uniaxial strain epsilon(zz), leading to a divergent band-edge absorbance for epsilon(zz) greater than or similar to 6%. Shear strain breaks the crystal symmetry and leads...

  1. Optical properties of potential condensates in exoplanetary atmospheres

    Science.gov (United States)

    Kitzmann, Daniel; Heng, Kevin

    2018-03-01

    The prevalence of clouds in currently observable exoplanetary atmospheres motivates the compilation and calculation of their optical properties. First, we present a new open-source Mie scattering code known as LX-MIE, which is able to consider large-size parameters (˜107) using a single computational treatment. We validate LX-MIE against the classical MIEVO code as well as previous studies. Secondly, we embark on an expanded survey of the published literature for both the real and imaginary components of the refractive indices of 32 condensate species. As much as possible, we rely on experimental measurements of the refractive indices and resort to obtaining the real from the imaginary component (or vice versa), via the Kramers-Kronig relation, only in the absence of data. We use these refractive indices as input for LX-MIE to compute the absorption, scattering and extinction efficiencies of all 32 condensate species. Finally, we use a three-parameter function to provide convenient fits to the shape of the extinction efficiency curve. We show that the errors associated with these simple fits in the Wide Field Camera 3 (WFC3), J, H, and K wavebands are ˜ 10 per cent. These fits allow for the extinction cross-section or opacity of the condensate species to be easily included in retrieval analyses of transmission spectra. We discuss prospects for future experimental work. The compilation of the optical constants and LX-MIE is publicly available as part of the open-source Exoclime Simulation Platform (http://www.exoclime.org).

  2. Electronic, structural, and optical properties of crystalline yttria

    International Nuclear Information System (INIS)

    Xu, Y.; Gu, Z.; Ching, W.Y.

    1997-01-01

    The electronic structure of crystalline Y 2 O 3 is investigated by first-principles calculations within the local-density approximation (LDA) of the density-functional theory. Results are presented for the band structure, the total density of states (DOS), the atom- and orbital-resolved partial DOS, effective charges, bond order, and charge-density distributions. Partial covalent character in the Y-O bonding is shown, and the nonequivalency of the two Y sites is demonstrated. The calculated electronic structure is compared with a variety of available experimental data. The total energy of the crystal is calculated as a function of crystal volume. A bulk modulus B of 183 Gpa and a pressure coefficient B ' of 4.01 are obtained, which are in good agreement with compression data. An LDA band gap of 4.54 eV at Γ is obtained which increases with pressure at a rate of dE g /dP=0.012eV/Gpa at the equilibrium volume. Also investigated are the optical properties of Y 2 O 3 up to a photon energy of 20 eV. The calculated complex dielectric function and electron-energy-loss function are in good agreement with experimental data. A static dielectric constant of var-epsilon(0)=3.20 is obtained. It is also found that the bottom of the conduction band consists of a single band, and direct optical transition at Γ between the top of the valence band and the bottom of the conduction band may be symmetry forbidden. copyright 1997 The American Physical Society

  3. Electrical and optical properties of nickel ferrite/polyaniline nanocomposite

    Directory of Open Access Journals (Sweden)

    M. Khairy

    2015-07-01

    Full Text Available Polyaniline–NiFe2O4 nanocomposites (PANI–NiFe2O4 with different contents of NiFe2O4 (2.5, 5 and 50 wt% were prepared via in situ chemical oxidation polymerization, while the nanoparticles nickel ferrite were synthesized by sol–gel method. The prepared samples were characterized using some techniques such as Fourier transforms infrared (FTIR, X-ray diffraction (XRD, scanning electron microscopy (SEM and thermogravimetric analysis (TGA. Moreover, the electrical conductivity and optical properties of the nanocomposites were investigated. Pure (PANI and the composites containing 2.5 and 5 wt% NiFe2O4 showed amorphous structures, while the one with 50 wt% NiFe2O4 showed a spinel crystalline structure. The SEM images of the composites showed different aggregations for the different nickel ferrite contents. FTIR spectra revealed to the formation of some interactions between the PANI macromolecule and the NiFe2O4 nanoparticles, while the thermal analyses indicated an increase in the composites stability for samples with higher NiFe2O4 nanoparticles contents. The electrical conductivity of PANI–NiFe2O4 nanocomposite was found to increase with the rise in NiFe2O4 nanoparticle content, probably due to the polaron/bipolaron formation. The optical absorption experiments illustrate direct transition with an energy band gap of Eg = 1.0 for PANI–NiFe2O4 nanocomposite.

  4. Variability of aerosol optical properties in the Western Mediterranean Basin

    Directory of Open Access Journals (Sweden)

    M. Pandolfi

    2011-08-01

    Full Text Available Aerosol light scattering, absorption and particulate matter (PM concentrations were measured at Montseny, a regional background site in the Western Mediterranean Basin (WMB which is part of the European Supersite for Atmospheric Aerosol Research (EUSAAR. Off line analyses of 24 h PM filters collected with Hi-Vol instruments were performed for the determination of the main chemical components of PM. Mean scattering and hemispheric backscattering coefficients (@ 635 nm were 26.6±23.2 Mm−1 and 4.3±2.7 Mm−1, respectively and the mean aerosol absorption coefficient (@ 637 nm was 2.8±2.2 Mm−1. Mean values of Single Scattering Albedo (SSA and Ångström exponent (å (calculated from 450 nm to 635 nm at MSY were 0.90±0.05 and 1.3±0.5 respectively. A clear relationship was observed between the PM1/PM10 and PM2.5/PM10 ratios as a function of the calculated Ångström exponents. Mass scattering cross sections (MSC for fine mass and sulfate at 635 nm were 2.8±0.5 m2 g−1 and 11.8±2.2 m2 g−1, respectively, while the mean aerosol absorption cross section (MAC was 10.4±2.0 m2 g−1. The variability in aerosol optical properties in the WMB were largely explained by the origin and ageing of air masses over the measurement site. The MAC values appear dependent of particles aging: similar to the expected absorption cross-section for fresh emissions under Atlantic Advection episodes and higher under aerosol pollution episodes. The analysis of the Ångström exponent as a function of the origin the air masses revealed that polluted winter anticyclonic conditions and summer recirculation scenarios typical of the WMB led to an increase of fine particles in the atmosphere (å = 1.5±0.1 while the aerosol optical properties under Atlantic Advection episodes and Saharan dust outbreaks were clearly

  5. Linear Optical Properties of Zinc Borotellurite Glass Doped with Lanthanum Oxide Nanoparticles for Optoelectronic and Photonic Application

    Directory of Open Access Journals (Sweden)

    Faznny Mohd Fudzi

    2017-01-01

    Full Text Available Enhancing the optical properties of glasses for the sake of optical application in various fields is an ongoing challenge in materials science and technology. Thus, the optical properties of zinc borotellurite glass doped with lanthanum oxide nanoparticles (La2O3 NPs with the chemical composition of {[(TeO20.7(B2O30.3]0.7(ZnO0.3}1−x (La2O3 NPsx, where x = 0.01, 0.02, 0.03, 0.04, and 0.05 molar fraction, have been investigated. Characterization techniques such as x-ray diffraction, Fourier Transform Infrared Spectroscopy, and Ultraviolet-Visible Spectroscopy are employed to yield the structural properties and optical parameter of the glass. The amorphous nature of the fabricated glasses is confirmed with the presence of a broad hump via XRD diffraction pattern. The decreasing amount of high polarizable nonbridging oxygen as the concentration of La2O3 NPs increases has contributed to the increasing trend of energy band gap in the range of 2.70 to 3.52 eV and decreasing value of refractive index between 2.34 and 2.48. The fabricated glasses that have a higher refractive index than the widely used fiber material, pure silica glass, indicate that zinc borotellurite glass doped with lanthanum nanoparticles is a promising material to be applied as optical fibers.

  6. Structure and optical properties of water covered Cu(110) surfaces

    International Nuclear Information System (INIS)

    Baghbanpourasl, A.

    2014-01-01

    In this thesis structural and optical properties of the water covered Cu(110) surface is studied using density functional theory within independent particle approximation. Several stable adsorption structures are studied such as water clusters (monomer, dimer, trimer, tetramer and pentamer), different hexagonal monolayers, partially dissociated water monolayers and three different types of chains among them a chain that consists of pentagon rings. For a copper surface in contact with water vapor, the energetically stable H 2 O/OH adsorbed structures are compared thermodynamically using adsorption free energy (change of free energy due to adsorption). Several phase diagrams with respect to temperature and pressure are calculated. It is found that among the large number of energetically stable structures (i.e. structures with positive adsorption energy ) only limited number of them are thermodynamically stable. These thermodynamically stable structures are the class of almost energetically degenerate hexagonal overlayers, one type of partially dissociated water structure that contains Bjerrum defect in the hydrogen bond network and pentagon chain. Since hydrogen atoms are light weight their vibrational effects can be considerable. Zero point vibration decreases the adsorption energy up to 0.1 eV and free energy of adsorbed molecules arising from vibrational degree of freedom can go up to -0.2 eV per adsorbed molecule at 500 Kelvin. However zero point energy and vibrational free energy of adsorbed molecules do not alter relative stability of the adsorbed structures. To account for the long range van der Waals interactions, a semi-empirical scheme is applied. Reflectance Anisotropy Spectroscopy (RAS) is a fast and non destructive optical method that can be used to prob the surface in different conditions such as vacuum and electro-chemical environment. Elasto-optic coeficients of bulk are calculated from first principles and the change of the RA spectrum of the bare Cu

  7. Nonlinear Optical Properties of Aluminum Doped Zinc Oxide

    Science.gov (United States)

    Otieno, Calford O.

    Nonlinear optical (NLO) materials are crucial to future progress in industrial and technological applications that involve intense light-matter interaction. While ZnO-related materials are known to possess good NLO properties, existing results on ZnO and AZO (Al-doped ZnO) are mostly available at a single wavelength or limited ranges. Therefore, NLO dispersions (wavelength dependences) are not entirely studied, especially at longer wavelengths far below the bandgap. It is important to explore wavelength dependences since doping can induce a drastic change in the NLO responses at varied spectral ranges via doping-induced subgap-state contributions. We present results of our studies on nonlinear harmonic generation from our samples, which include 1) second harmonic generation and 2) third harmonic generation precisely characterized by Maker fringes as a function of both Al doping and wavelength. We exhaustively discuss the possible cause for the modified optical nonlinearities observed in our AZO thin films and give detailed comparisons of our observations with the previous studies. We also present the results of open- and close-aperture Z-scans to characterize the two-photon absorption coefficient (TPA) and the nonlinear refractive index (NLR), respectively, of the AZO films. There was no clearcut evidence of monotonic dependence of TPA and NLR on doping. This presumably indicates that the overall effect is nontrivial and should be understood in terms of combined effects of bandgap shift and crystallinity upon varying the doping level. Most intriguingly, we found that NLR values from the closed-aperture Z-scan are very large by orders of magnitude when compared with the bulk counterparts. Similar observation was made for TPA values from the open-aperture Z-scan. To countercheck very large NLO absorption, we conducted simple intensity scan by varying the incident photon number on each sample but fixing the beam area to eliminate any possible errors related to optical

  8. Electronic Structure and Optical Properties Of EuIn2P2

    KAUST Repository

    Singh, Nirpendra

    2011-10-25

    The electronic structures and, optical and magneto‐optical properties of a newly found Zintl compound EuIn2P2 have been investigated within the density‐functional theory using the highly precise full‐potential linear‐augmented‐plane‐wave method. Results of detailed investigation of the electronic structure and related properties are reported.

  9. The effects of thermal annealing in structural and optical properties of RF sputtered amorphous silicon

    International Nuclear Information System (INIS)

    Abdul Fatah Awang Mat

    1988-01-01

    The effect of thermal annealing on structural and optical properties of amorphous silicon are studied on samples prepared by radio-frequency sputtering. The fundamental absorption edge of these films are investigated at room temperature and their respective parameters estimated. Annealing effect on optical properties is interpreted in terms of the removal of voids and a decrease of disorder. (author)

  10. Synthesis and Optical Properties of Trioxatriangulenium Dyes with One and Two Peripheral Amino Substituents

    DEFF Research Database (Denmark)

    Sørensen, Thomas Just; Laursen, Bo Wegge

    2010-01-01

    -substituted triphenylmethylium (TPM) compounds by aromatic nucleophilic substitution with secondary amines and subsequent intramolecular ring closure. The optical properties of the new triangulenium dyes and their TPM precursors were investigated and compared to those of known TPM and xanthenium dyes. The optical properties...

  11. Radiation-optical properties of the glasses for the space application

    International Nuclear Information System (INIS)

    Akishin, A.I.; Tseplyaev, L.I.

    2006-01-01

    The data are presented and generalized on variations of optical properties of glass and light guides under simulative cosmic ionizing radiation. It is shown that changes in optical properties (coloration, bleaching, opacity, luminescence) under ionizing radiation are associated with color centers formation and annealing [ru

  12. Integrating sphere-based setup as an accurate system for optical properties measurements

    CSIR Research Space (South Africa)

    Abdalmonem, S

    2010-09-01

    Full Text Available Determination of the optical properties of solid and liquid samples has great importance. Since the integrating sphere-based setup is used to measure the amount of reflected and transmitted light by the examined samples, optical properties could...

  13. Optical Properties of Complex Plasmonic Materials Studied with Extended Effective Medium Theories Combined with Rigorous Coupled Wave Analysis

    Directory of Open Access Journals (Sweden)

    Elie Nadal

    2018-02-01

    Full Text Available In this study we fabricate gold nanocomposites and model their optical properties. The nanocomposites are either homogeneous films or gratings containing gold nanoparticles embedded in a polymer matrix. The samples are fabricated using a recently developed technique making use of laser interferometry. The gratings present original plasmon-enhanced diffraction properties. In this work, we develop a new approach to model the optical properties of our composites. We combine the extended Maxwell–Garnett model of effective media with the Rigorous Coupled Wave Analysis (RCWA method and compute both the absorption spectra and the diffraction efficiency spectra of the gratings. We show that such a semi-analytical approach allows us to reproduce the original plasmonic features of the composites and can provide us with details about their inner structure. Such an approach, considering reasonably high particle concentrations, could be a simple and efficient tool to study complex micro-structured system based on plasmonic components, such as metamaterials.

  14. 2014 Enhanced LAW Glass Property-Composition Models, Phase 2

    Energy Technology Data Exchange (ETDEWEB)

    Muller, Isabelle [The Catholic Univ. of America, Washington, DC (United States); Pegg, Ian L. [The Catholic Univ. of America, Washington, DC (United States); Joseph, Innocent [Energy Solutions, Salt Lake City, UT (United States); Gilbo, Konstantin [The Catholic Univ. of America, Washington, DC (United States)

    2015-10-28

    This report describes the results of testing specified by the Enhanced LAW Glass Property-Composition Models, VSL-13T3050-1, Rev. 0 Test Plan. The work was performed in compliance with the quality assurance requirements specified in the Test Plan. Results required by the Test Plan are reported. The te4st results and this report have been reviewed for correctness, technical adequacy, completeness, and accuracy.

  15. Structural characterizations and optical properties of new Li–Sr–Nb-phosphate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Yi-Mu [Department of Electronic Engineering, National United University, Miao-Li 36003, Taiwan, ROC (China); Hsu, S.M. [Department of Biomedical Imaging and Radiological Sciences, National Yang-Ming University, Taipei 11221, Taiwan, ROC (China); Yung, S.W., E-mail: hwyang@nuu.edu.tw [Department of Material Science and Engineering, National United University, Miao-Li 36003, Taiwan, ROC (China); Zhang, T. [Institute for Materials Research, Fuzhou University, Fujian (China); Huang, Y.S.; Wu, J.J. [Department of Material Science and Engineering, National United University, Miao-Li 36003, Taiwan, ROC (China); Hsu, C.H. [Department of Electrical Engineering, National United University, Miao-Li 36003, Taiwan, ROC (China); Chin, T.S. [Department of Materials Science and Engineering, Feng Chia University, Taichung, Taiwan, ROC (China)

    2014-04-01

    A new Li{sub 2}O–SrO–Nb{sub 2}O{sub 5}–P{sub 2}O{sub 5} glass system was prepared by a high-temperature alumina crucible, and structural characterization and optical properties were investigated. Proper content of Li{sub 2}O and Nb{sub 2}O{sub 5} was employed to replace partial SrO and P{sub 2}O{sub 5} to improve the optical properties. It was observed that the enhancement of the refractive index from 1.75 to 1.85 is mainly due to the Nb{sub 2}O{sub 5} content. An addition of Li{sub 2}O significantly increases the optical transmittance; optical transparency can be enhanced from 60% to higher than 85% in the UV–visible region with addition of 20–40 mol% Li{sub 2}O species. However, optical transmittance is monotonically decreased from about 90% to 80% under 10–30 mol% Nb{sub 2}O{sub 5} addition. The 40P{sub 2}O{sub 5}–20Nb{sub 2}O{sub 5}–20SrO–20Li{sub 2}O glasses demonstrate the optimum refractive index (n > 1.75) and high optical transparency (>80%) in the UV–visible region. Furthermore, the effect of Nb{sub 2}O{sub 5} on the structural transition was focused on the (60 − y)P{sub 2}O{sub 5}–yNb{sub 2}O{sub 5}–20SrO–20Li{sub 2}O vitreous system since the transition of FTIR spectra reveals that the Nb{sub 2}O{sub 5} has more pronounced effect than Li{sub 2}O in the glass network due to the higher covalent extent and electronegativity. Addition of Nb{sub 2}O{sub 5} generates Nb–O bonds by dissociating P–O chains and results in the decrease in the intensity of the (PO{sub 2}), (POP), and (PO{sub 3}) absorption bands. The O1s-XPS analysis shows that Nb{sub 2}O{sub 5} addition dissociates symmetric bridging oxygens in P–O–P bonding and forms asymmetric bridging oxygens in P–O–Nb and non-bridging Nb–O{sup -} bonds, in which octahedral [NbO{sub 6}] unit is eventually substituted by [NbO{sub 4}] tetrahedral unit in the Li–Sr–Nb phosphate glasses. - Highlights: • The prepared glasses demonstrate great optical properties

  16. The Use Of Optical Properties Of Cr-39 In Alpha Particle Equivalent Dose Measurements

    International Nuclear Information System (INIS)

    Shnishin, K.A.

    2007-01-01

    In this work, optical properties of alpha irradiated Cr-39 were measured as a function of optical photon wavelength from 200-1100 nm. Optical energy gap and optical absorption at finite wavelength was also calculated and correlated to alpha fluence and dose equivalent. Alpha doses were calculated from the corresponding irradiation fluence and specific energy loss using TRIM computer program. It was found that, the optical absorption of unattached Cr-39 was varied with alpha fluence and corresponding equivalent doses. Also the optical energy gab was varied with fluence and dose equivalent of alpha particles. This work introduces a reasonably simple method for the Rn dose equivalent calculation by Cr-39 track

  17. Structural and optical properties of Eu3+ activated low cost zinc soda lime silica glasses

    Directory of Open Access Journals (Sweden)

    Nur Alia Sheh Omar

    Full Text Available A low cost method was employed to synthesize ZnO-SLS:xEu3+ phosphors using recyclable bottle glass as silica source. The structural and optical properties of ZnO-SLS:xEu3+ (x = 0, 1, 2, 3, 4 and 5 wt.% glasses were determined using X-ray diffraction (XRD, Fourier transform infrared reflectance (FTIR, UV-visible (Uv-Vis and photoluminescence (PL spectroscopy. Structural investigation using XRD measurement had broadened the halo peak with the doping of dopants. FTIR spectra showed the glass system consists of –OH and SiO4 bands. Meanwhile, the optical measurement using UV-Vis absorption has been induced a blue shift of the electronic absorption edge. The emission peak intensity of ZnO-SLS:xEu3+ phosphors was enhanced with the progression of doping concentration and thus, revealed their potential as red emitting phosphors under 400 nm excitation. Keywords: Eu3+ doped ZnO-SLS glasses, Solid state method, Optical band gap, Photoluminescence

  18. Optical and structural properties of nanostructured CeO2:Tb3+ film

    International Nuclear Information System (INIS)

    Ansari, Anees A.; Singh, S.P.; Malhotra, B.D.

    2011-01-01

    Nanostructured CeO 2 :Tb 3+ film has been fabricated on glass substrate through sol-gel technique via dip-coating process. (NH 4 ) 2 Ce(NO 3 ) 6 , Tb(NO 3 ) 3 .6H 2 O, ethylene glycol have been used as precursors for sol preparation. X-ray diffraction (XRD), scanning electron microscopy (SEM), UV/VIS and photoluminescence (PL) spectral studies have been employed to analyze the structural and optical properties of the film. XRD pattern has been used to analyze the crystallite nature and calculated particle size by Scherrer equation of nanostructured CeO 2 :Tb 3+ film, found in the range 3-4 nm. SEM image has been observed to analyze the surface topography of the film which is well porous, highly agglomerated and uniformly distributed nanoparticles on the film surface. Optical band gap of nanostructured CeO 2 :Tb 3+ film has been estimated as 3.57 eV. A significant enhancement in band shape of CeO 2 :Tb 3+ spectrum has been observed in PL spectra, showed their promising usages as optical materials in optoelectronic devices.

  19. Natural Silk as a Photonics Component: a Study on Its Light Guiding and Nonlinear Optical Properties

    OpenAIRE

    Kujala, Sami; Mannila, Anna; Karvonen, Lasse; Kieu, Khanh; Sun, Zhipei

    2016-01-01

    Silk fibers are expected to become a pathway to biocompatible and bioresorbable waveguides, which could be used to deliver localized optical power for various applications, e.g., optical therapy or imaging inside living tissue. Here, for the first time, the linear and nonlinear optical properties of natural silk fibers have been studied. The waveguiding properties of silk fibroin of largely unprocessed Bombyx mori silkworm silk are assessed using two complementary methods, and found to be on ...

  20. Electronic band structure and optical properties of antimony selenide under pressure

    Energy Technology Data Exchange (ETDEWEB)

    Abhijit, B.K.; Jayaraman, Aditya; Molli, Muralikrishna, E-mail: muralikrishnamolli@sssihl.edu.in [Department of Physics, Sri Sathya Sai Institute of Higher Learning, Prasanthinilayam, 515 134 (India)

    2016-05-23

    In this work we present the optical properties of Antimony Selenide (Sb{sub 2}Se{sub 3}) under ambient conditions and under pressure of 9.2 GPa obtained using first principles calculations. We investigated the electronic band structure using the FP-LAPW method within the sphere of the density functional theory. Optical properties like refractive index, absorption coefficient and optical conductivity are calculated using the WIEN2k code.

  1. Ultrathin and Nanostructured Au Films with Gradient of Effective Thickness. Optical and Plasmonic Properties

    International Nuclear Information System (INIS)

    Tomilin, S V; Berzhansky, V N; Shaposhnikov, A N; Prokopov, A R; Milyukova, E T; Karavaynikov, A V; Tomilina, O A

    2016-01-01

    In present work the results of investigation of optical (transmission spectra) and plasmonic (surface plasmon-polariton resonance) properties of ultrathin and nanostructured Au films are presents. Methods and techniques for the syntheses of samples of ultrathin and nanostructured metallic films, and for the experimental studies of optical and plasmonic properties are representative. Au films on SiO 2 (optic glass) substrates were investigated. (paper)

  2. Optical properties of Cd Se thin films obtained by pyrolytic dew

    International Nuclear Information System (INIS)

    Perez G, A.M.; Tepantlan, C.S.; Renero C, F.

    2006-01-01

    In this paper the optical properties of Cd Se thin films obtained by spray pyrolysis are presented. The films are prepared by Sodium Seleno sulphate (Na 2 SSeO 3 ) and Cadmium Chloride (CdC 12 ) mixing in aqueous environment. Optical parameters of the films (refractive index, absorption coefficient and optical ban gap) were calculated from transmittance spectra. The obtained values of the optical ban gap are compared with the result obtained by other deposition method. (Author)

  3. Optical and electronic properties of polyvinyl alcohol doped with pairs of mixed valence metal ions

    International Nuclear Information System (INIS)

    Bulinski, Mircea; Kuncser, Victor; Plapcianu, Carmen; Krautwald, Stefan; Franke, Hilmar; Rotaru, P; Filoti, George

    2004-01-01

    The electronic mechanisms induced by the UV exposure of thin films of polyvinyl alcohol doped with pairs of mixed valence metal ions were studied in relation to their optical behaviour by Moessbauer spectroscopy and optical absorption. The results obtained definitely point to the role of each element from the pair in the electronic mechanism involved, with influence on the optical properties regarding applications in real-time holography and integrated optics

  4. Novel Chiroptical Analysis of Hemoglobin by Surface Enhanced Resonance Raman Optical Activity Spectroscopy

    DEFF Research Database (Denmark)

    Brazhe, Nadezda; Brazhe, Alexey; Sosnovtseva, Olga

    2010-01-01

    The metalloprotein hemoglobin (Hb) was studied using surface enhanced resonance Raman spectroscopy (SERRS) and surface enhanced resonance Raman optical activity (SERROA). The SERROA results are analyzed and compared with the SERRS, and the later to the resonance Raman (RRS) performed on Hb...

  5. Optical properties of CeO2 thin films

    Indian Academy of Sciences (India)

    TECS

    Keywords. Transmittance; absorption coefficient; refractive index; optical band gap. 1. Introduction ... Several studies were reported on the optical and elec- trochemical ... In order to determine the values of optical band gap,. (αhν) r vs hν curve ...

  6. Enhanced and tunable optical quantum efficiencies from plasmon bandwidth engineering in bimetallic CoAg nanoparticles

    Directory of Open Access Journals (Sweden)

    A. Malasi

    2016-10-01

    Full Text Available Plasmonic nanoparticles are amongst the most effective ways to resonantly couple optical energy into and out of nanometer sized volumes. However, controlling and/or tuning the transfer of this incident energy to the surrounding near and far field is one of the most interesting challenges in this area. Due to the dielectric properties of metallic silver (Ag, its nanoparticles have amongst the highest radiative quantum efficiencies (η, i.e., the ability to radiatively transfer the incident energy to the surrounding. Here we report the discovery that bimetallic nanoparticles of Ag made with immiscible and plasmonically weak Co metal can show comparable and/or even higher η values. The enhancement is a result of the narrowing of the plasmon bandwidth from these bimetal systems. The phenomenological explanation of this effect based on the dipolar approximation points to the reduction in radiative losses within the Ag nanoparticles when in contact with cobalt. This is also supported by a model of coupling between poor and good conductors based on the surface to volume ratio. This study presents a new type of bandwidth engineering, one based on using bimetal nanostructures, to tune and/or enhance the quality factor and quantum efficiency for near and far-field plasmonic applications.

  7. Optical properties of two-dimensional charge density wave materials

    Science.gov (United States)

    Sayers, Charles; Karbassi, Sara; Friedemann, Sven; da Como, Enrico

    Titanium diselenide (TiSe2) is a member of the layered transition metal dichalcogenide (TMD) materials. It exhibits unusual chiral charge ordering below 190 K after undergoing an initial phase transition to a commensurate (2 x 2 x 2) charge density wave (CDW) at 200 K which is enhanced further in the monolayer. Recently, the first evidence of chirality in a CDW system was discovered in this material by scanning tunneling microscopy and time-resolved reflectivity experiments, where separate left and right handed charge-ordered domains were found to exist within a single sample. We have prepared single crystals of 1T-TiSe2 using iodine vapour transport, and confirmed their quality by x-ray analysis and charge transport measurements. Using a combination of polarised optical spectroscopy techniques in the mid to far infrared (4 to 700 meV photon energy), we have measured an anisotropy relating to the CDW gap. We discuss the results on the basis of chiral domains with different handedness and the nature of the CDW transition.

  8. Structural and optical properties of chlorinated plasma polymers

    International Nuclear Information System (INIS)

    Turri, Rafael; Davanzo, Celso U.; Schreiner, Wido; Dias da Silva, José Humberto; Appolinario, Marcelo Borgatto; Durrant, Steven F.

    2011-01-01

    Amorphous hydrogenated chlorinated carbon (a-C:H:Cl) films were produced by the plasma polymerization of chloroform–acetylene–argon mixtures in a radiofrequency plasma enhanced chemical vapor deposition system. The main parameter of interest was the proportion of chloroform in the feed, R C , which was varied from 0 to 80%. Deposition rates of 80 nm min −1 were typical for the chlorinated films. Infrared reflection–absorption spectroscopy revealed the presence of C–Cl groups in all the films produced with chloroform in the feed. X-ray photoelectron spectroscopy confirmed this finding, and revealed a saturation of the chlorine content at ∼ 47 at.% for R C ≥ 40%. The refractive index and optical gap, E 04 , of the films were roughly in the 1.6 to 1.7, and the 2.8 to 3.7 eV range. These values were calculated from transmission ultraviolet–visible-near infrared spectra. Chlorination leads to an increase in the water surface contact angle from ∼ 40° to ∼ 77°.

  9. Structural and optical properties of chlorinated plasma polymers

    Energy Technology Data Exchange (ETDEWEB)

    Turri, Rafael [Laboratorio de Plasmas Tecnologicos, Campus Experimental de Sorocaba, Universidade Estadual Paulista (UNESP), Avenida Tres de Marco 511, Alto de Boa Vista, 18087-180, Sorocaba, SP (Brazil); Davanzo, Celso U. [Instituto de Quimica, Universidade Estadual de Campinas, Campinas, SP (Brazil); Schreiner, Wido [Departamento de Fisica, Universidade Federal de Parana, PR (Brazil); Dias da Silva, Jose Humberto [Faculdade de Ciencias, Universidade Estadual Paulista (UNESP), Bauru, SP (Brazil); Appolinario, Marcelo Borgatto [Laboratorio de Plasmas Tecnologicos, Campus Experimental de Sorocaba, Universidade Estadual Paulista (UNESP), Avenida Tres de Marco 511, Alto de Boa Vista, 18087-180, Sorocaba, SP (Brazil); Durrant, Steven F., E-mail: steve@sorocaba.unesp.br [Laboratorio de Plasmas Tecnologicos, Campus Experimental de Sorocaba, Universidade Estadual Paulista (UNESP), Avenida Tres de Marco 511, Alto de Boa Vista, 18087-180, Sorocaba, SP (Brazil)

    2011-12-30

    Amorphous hydrogenated chlorinated carbon (a-C:H:Cl) films were produced by the plasma polymerization of chloroform-acetylene-argon mixtures in a radiofrequency plasma enhanced chemical vapor deposition system. The main parameter of interest was the proportion of chloroform in the feed, R{sub C}, which was varied from 0 to 80%. Deposition rates of 80 nm min{sup -1} were typical for the chlorinated films. Infrared reflection-absorption spectroscopy revealed the presence of C-Cl groups in all the films produced with chloroform in the feed. X-ray photoelectron spectroscopy confirmed this finding, and revealed a saturation of the chlorine content at {approx} 47 at.% for R{sub C} {>=} 40%. The refractive index and optical gap, E{sub 04}, of the films were roughly in the 1.6 to 1.7, and the 2.8 to 3.7 eV range. These values were calculated from transmission ultraviolet-visible-near infrared spectra. Chlorination leads to an increase in the water surface contact angle from {approx} 40 Degree-Sign to {approx} 77 Degree-Sign .

  10. Advanced optical measurements for characterizing photophysical properties of single nanoparticles.

    Energy Technology Data Exchange (ETDEWEB)

    Polsky, Ronen; Davis, Ryan W.; Arango, Dulce C.; Brozik, Susan Marie; Wheeler, David Roger

    2009-09-01

    Formation of complex nanomaterials would ideally involve single-pot reaction conditions with one reactive site per nanoparticle, resulting in a high yield of incrementally modified or oriented structures. Many studies in nanoparticle functionalization have sought to generate highly uniform nanoparticles with tailorable surface chemistry necessary to produce such conjugates, with limited success. In order to overcome these limitations, we have modified commercially available nanoparticles with multiple potential reaction sites for conjugation with single ssDNAs, proteins, and small unilamellar vesicles. These approaches combined heterobifunctional and biochemical template chemistries with single molecule optical methods for improved control of nanomaterial functionalization. Several interesting analytical results have been achieved by leveraging techniques unique to SNL, and provide multiple paths for future improvements for multiplex nanoparticle synthesis and characterization. Hyperspectral imaging has proven especially useful for assaying substrate immobilized fluorescent particles. In dynamic environments, temporal correlation spectroscopies have been employed for tracking changes in diffusion/hydrodynamic radii, particle size distributions, and identifying mobile versus immobile sample fractions at unbounded dilution. Finally, Raman fingerprinting of biological conjugates has been enabled by resonant signal enhancement provided by intimate interactions with nanoparticles and composite nanoshells.

  11. Probing the micro-rheological properties of aerosol particles using optical tweezers

    International Nuclear Information System (INIS)

    Power, Rory M; Reid, Jonathan P

    2014-01-01

    The use of optical trapping techniques to manipulate probe particles for performing micro-rheological measurements on a surrounding fluid is well-established. Here, we review recent advances made in the use of optical trapping to probe the rheological properties of trapped particles themselves. In particular, we review observations of the continuous transition from liquid to solid-like viscosity of sub-picolitre supersaturated solution aerosol droplets using optical trapping techniques. Direct measurements of the viscosity of the particle bulk are derived from the damped oscillations in shape following coalescence of two particles, a consequence of the interplay between viscous and surface forces and the capillary driven relaxation of the approximately spheroidal composite particle. Holographic optical tweezers provide a facile method for the manipulation of arrays of particles allowing coalescence to be controllably induced between two micron-sized aerosol particles. The optical forces, while sufficiently strong to confine the composite particle, are several orders of magnitude weaker than the capillary forces driving relaxation. Light, elastically back-scattered by the particle, is recorded with sub-100 ns resolution allowing measurements of fast relaxation (low viscosity) dynamics, while the brightfield image can be used to monitor the shape relaxation extending to times in excess of 1000 s. For the slowest relaxation dynamics studied (particles with the highest viscosity) the presence and line shape of whispering gallery modes in the cavity enhanced Raman spectrum can be used to infer the relaxation time while serving the dual purpose of allowing the droplet size and refractive index to be measured with accuracies of ±0.025% and ±0.1%, respectively. The time constant for the damped relaxation can be used to infer the bulk viscosity, spanning from the dilute solution limit to a value approaching that of a glass, typically considered to be >10 12

  12. Probing the micro-rheological properties of aerosol particles using optical tweezers

    Science.gov (United States)

    Power, Rory M.; Reid, Jonathan P.

    2014-07-01

    The use of optical trapping techniques to manipulate probe particles for performing micro-rheological measurements on a surrounding fluid is well-established. Here, we review recent advances made in the use of optical trapping to probe the rheological properties of trapped particles themselves. In particular, we review observations of the continuous transition from liquid to solid-like viscosity of sub-picolitre supersaturated solution aerosol droplets using optical trapping techniques. Direct measurements of the viscosity of the particle bulk are derived from the damped oscillations in shape following coalescence of two particles, a consequence of the interplay between viscous and surface forces and the capillary driven relaxation of the approximately spheroidal composite particle. Holographic optical tweezers provide a facile method for the manipulation of arrays of particles allowing coalescence to be controllably induced between two micron-sized aerosol particles. The optical forces, while sufficiently strong to confine the composite particle, are several orders of magnitude weaker than the capillary forces driving relaxation. Light, elastically back-scattered by the particle, is recorded with sub-100 ns resolution allowing measurements of fast relaxation (low viscosity) dynamics, while the brightfield image can be used to monitor the shape relaxation extending to times in excess of 1000 s. For the slowest relaxation dynamics studied (particles with the highest viscosity) the presence and line shape of whispering gallery modes in the cavity enhanced Raman spectrum can be used to infer the relaxation time while serving the dual purpose of allowing the droplet size and refractive index to be measured with accuracies of ±0.025% and ±0.1%, respectively. The time constant for the damped relaxation can be used to infer the bulk viscosity, spanning from the dilute solution limit to a value approaching that of a glass, typically considered to be >1012 Pa s, whilst

  13. Influence of the radio-frequency power on the physical and optical properties of plasma polymerized cyclohexane thin films

    Energy Technology Data Exchange (ETDEWEB)

    Manaa, C., E-mail: chadlia.el.manaa@gmail.com [Laboratoire de Physique de la Matière Condensée, Université de Picardie Jules Verne, UFR des Sciences d' Amiens, 33 rue Saint Leu, 80039 Amiens CEDEX 2 (France); Laboratoire des Matériaux Avancés et Phénomènes Quantiques, Université de Tunis El-Manar, Faculté des Sciences de Tunis, Campus universitaire El-Manar, 1068 Tunis (Tunisia); Lejeune, M. [Laboratoire de Physique de la Matière Condensée, Université de Picardie Jules Verne, UFR des Sciences d' Amiens, 33 rue Saint Leu, 80039 Amiens CEDEX 2 (France); Kouki, F. [Laboratoire des Matériaux Avancés et Phénomènes Quantiques, Université de Tunis El-Manar, Faculté des Sciences de Tunis, Campus universitaire El-Manar, 1068 Tunis (Tunisia); Durand-Drouhin, O. [Laboratoire de Physique de la Matière Condensée, Université de Picardie Jules Verne, UFR des Sciences d' Amiens, 33 rue Saint Leu, 80039 Amiens CEDEX 2 (France); Bouchriha, H. [Laboratoire des Matériaux Avancés et Phénomènes Quantiques, Université de Tunis El-Manar, Faculté des Sciences de Tunis, Campus universitaire El-Manar, 1068 Tunis (Tunisia); and others

    2014-06-02

    We investigate in the present study the effects of the radio-frequency plasma power on the opto-electronical properties of the polymeric amorphous hydrogenated carbon thin films deposited at room temperature and different radio-frequency powers by plasma-enhanced chemical vapor deposition method using cyclohexane as precursor. A combination of U.V.–Visible and infrared transmission measurements is applied to characterize the bonding and electronic properties of these films. Some film properties namely surface roughness, contact angle, surface energy, and optical properties are found to be significantly influenced by the radio-frequency power. The changes in these properties are analyzed within the microstructural modifications occurring during growth. - Highlights: • Effects of the radio-frequency power on the optoelectronic properties of thin films • Elaboration of plasma polymerized thin films using cyclohexane as precursor gas • The use of U.V.–Visible-infrared transmission, and optical gap • Study of the surface topography of the films by using Atomic Force microscopy • The use of a capacitively coupled plasma enhanced chemical vapor deposition method.

  14. Influence of the radio-frequency power on the physical and optical properties of plasma polymerized cyclohexane thin films

    International Nuclear Information System (INIS)

    Manaa, C.; Lejeune, M.; Kouki, F.; Durand-Drouhin, O.; Bouchriha, H.

    2014-01-01

    We investigate in the present study the effects of the radio-frequency plasma power on the opto-electronical properties of the polymeric amorphous hydrogenated carbon thin films deposited at room temperature and different radio-frequency powers by plasma-enhanced chemical vapor deposition method using cyclohexane as precursor. A combination of U.V.–Visible and infrared transmission measurements is applied to characterize the bonding and electronic properties of these films. Some film properties namely surface roughness, contact angle, surface energy, and optical properties are found to be significantly influenced by the radio-frequency power. The changes in these properties are analyzed within the microstructural modifications occurring during growth. - Highlights: • Effects of the radio-frequency power on the optoelectronic properties of thin films • Elaboration of plasma polymerized thin films using cyclohexane as precursor gas • The use of U.V.–Visible-infrared transmission, and optical gap • Study of the surface topography of the films by using Atomic Force microscopy • The use of a capacitively coupled plasma enhanced chemical vapor deposition method

  15. Electronic and optical properties of Y-doped Si{sub 3}N{sub 4} by density functional theory

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Zhifeng [State Key Lab of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070 (China); Chen, Fei, E-mail: chenfei027@gmail.com [State Key Lab of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070 (China); Key Laboratory of Advanced Technology for Specially Functional Materials, Ministry of Education, Wuhan University of Technology, Wuhan 430070 (China); Su, Rui; Wang, Zhihao; Li, Junyang; Shen, Qiang [State Key Lab of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070 (China); Zhang, Lianmeng [State Key Lab of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070 (China); Key Laboratory of Advanced Technology for Specially Functional Materials, Ministry of Education, Wuhan University of Technology, Wuhan 430070 (China)

    2015-07-15

    Highlights: • Y-doped α-Si{sub 3}N{sub 4} and β-Si{sub 3}N{sub 4} are systematically investigated by DFT. • Impacts of local structure and bond character on electronic property are studied. • Static dielectric constants and optical absorption properties are investigated. - Abstract: Geometry structures, formation energies, electronic and optical properties of Y-doped α-Si{sub 3}N{sub 4} and β-Si{sub 3}N{sub 4} are investigated based on the density functional theory (DFT). The low values of formation energies indicate both Y-doped Si{sub 3}N{sub 4} models can be easily synthesized. Besides, the negative formation energies of α-Y{sub i}-Si{sub 3}N{sub 4} demonstrate that interstitial Y-doped α-Si{sub 3}N{sub 4} has an excellent stability. The energies of impurity levels are different resulting from the different chemical environment around Y atoms. The impurity levels localized in the band gap reduces the maximum energy gaps, which enhances the optical properties of Si{sub 3}N{sub 4}. The static dielectric constants become larger and the optical absorption spectra show the red-shift phenomena for all Y-doped Si{sub 3}N{sub 4} models.

  16. Optical properties of humic substances and CDOM: effects of borohydride reduction.

    Science.gov (United States)

    Ma, Jiahai; Del Vecchio, Rossana; Golanoski, Kelli S; Boyle, Erin S; Blough, Neil V

    2010-07-15

    Treatment of Suwanee River humic (SRHA) and fulvic (SRFA) acids, a commercial lignin (LAC), and a series of solid phase extracts (C18) from the Middle Atlantic Bight (MAB extracts) with sodium borohydride (NaBH(4)), a selective reductant of carbonyl-containing compounds including quinones and aromatic ketones, produces a preferential loss of visible absorption (> or = 50% for SRFA) and substantially enhanced, blue-shifted fluorescence emission (2- to 3-fold increase). Comparison of the results with those obtained from a series of model quinones and hydroquinones demonstrates that these spectral changes cannot be assigned directly to the absorption and emission of visible light by quinones/hydroquinones. Instead, these results are consistent with a charge transfer model in which the visible absorption is due primarily to charge transfer transitions arising among hydroxy- (methoxy-) aromatic donors and carbonyl-containing acceptors. Unlike most of the model hydroquinones, the changes in optical properties of the natural samples following NaBH(4) reduction were largely irreversible in the presence of air and following addition of a Cu(2+) catalyst, providing tentative evidence that aromatic ketones (or other similar carbonyl-containing structures) may play a more important role than quinones in the optical properties of these materials.

  17. Methods of studying the optical properties of landscapes

    Directory of Open Access Journals (Sweden)

    Владислав Малышев

    2016-10-01

    Full Text Available The definition and systematization of dynamical changes and temporal variants of geosystems, comparative analysis and typological classification of geosystems based on the nature and totality of their conditions present one of the central problems in landscapes dynamics and the most important aspect of dynamic modelling problem. Currently, spectral characteristics of geosystems obtained by remote sensing techniques can be used in the study of landscape areas dynamic processes with considerable success, as the integrated value. The study of the landscapes properties on the basis of their optical properties was carried out in the test section of the Kursk aerospace polygon that includes Streletski site of the Central Chernozem V.V. Alekhin state biospheric natural reserve, a site of Kursk biospheric station and agribusinesses Panino. It included spectral and phytometric measurements in soil-vegetation cover by land and from the aircraft AN-2. Measurements of spectral characteristics with simultaneous obtaining of digital colour image in RJB channels and parameters of soil and vegetation cover in the mode in-situ were carried out on the experimental sites located in three areas of protected steppes with natural vegetation and different modes of nature use: not mowed, mowed, grazing; as well as agricultural systems with different crops. The spectral characteristics of images were obtained with photospectroscopic system FSS-M1 and the spectroradiometer of the FSR–M. Vegetation samples were taken from the experimental sites for further processing in laboratory conditions. In chamber conditions total phytomass and phytomass fractions (leaves, stems, stalks, flowers were measured. The leaf area and the projected area of the plants were calculated. The results of simultaneous ground-based and flight measurements are recorded in the field book (after treatment, in a specially designed book in Excel to create the database and conduct

  18. Barrier, mechanical and optical properties of whey protein concentrate films

    Directory of Open Access Journals (Sweden)

    Viviane Machado Azevedo

    2014-08-01

    Full Text Available Whey is recognized as a valuable source of high quality protein and, when processed as protein concentrate, may be used in the production of biodegradable films. The objective of the study was to develop films of whey protein concentrate 80% (WPC at concentrations of 6, 8, 10 and 12% and evaluate the influence of this factor in the barrier, mechanical and optical properties of the films. Treatments showed moisture content with a mean value of 22.10% ± 0.76and high solubility values between 56.67 to 62.42%. Thus, there is little or no influence of varying the concentration of WPC in these properties and high hydrophilicity of the films. With increasing concentration of WPC, increases the water vapor permeability of the films (7.42 x 10-13 to 3.49 x 10-12 g.m-1.s-1.Pa-1. The treatment at the concentration of 6% of WPC showed a higher modulus of elasticity (287.90 ± 41.79 MPa. Thegreater rigidity in films with higher concentrations is possibly due to the greater number of bonds between molecules of the polymeric matrix. The films have the same puncture resistance. The increased concentration of WPC promotes resistance to the action of a localized force. In general, films of whey protein concentrate in the tested concentrations exhibited slightly yellowish color and transparency, and can be used in food packaging that requiring intermediate permeability to water vapor, to keep moisture and texture desired.

  19. Active control of electromagnetic radiation through an enhanced thermo-optic effect

    Science.gov (United States)

    Sheng, Chong; Liu, Hui; Zhu, Shining; Genov, Dentcho A.

    2015-01-01

    The control of electromagnetic radiation in transformation optical metamaterials brings the development of vast variety of optical devices. Of a particular importance is the possibility to control the propagation of light with light. In this work, we use a structured planar cavity to enhance the thermo-optic effect in a transformation optical waveguide. In the process, a control laser produces apparent inhomogeneous refractive index change inside the waveguides. The trajectory of a second probe laser beam is then continuously tuned in the experiment. The experimental results agree well with the developed theory. The reported method can provide a new approach toward development of transformation optical devices where active all-optical control of the impinging light can be achieved. PMID:25746689

  20. Nanofluid optical property characterization: towards efficient direct absorption solar collectors

    Directory of Open Access Journals (Sweden)

    Otanicar Todd

    2011-01-01

    Full Text Available Abstract Suspensions of nanoparticles (i.e., particles with diameters < 100 nm in liquids, termed nanofluids, show remarkable thermal and optical property changes from the base liquid at low particle loadings. Recent studies also indicate that selected nanofluids may improve the efficiency of direct absorption solar thermal collectors. To determine the effectiveness of nanofluids in solar applications, their ability to convert light energy to thermal energy must be known. That is, their absorption of the solar spectrum must be established. Accordingly, this study compares model predictions to spectroscopic measurements of extinction coefficients over wavelengths that are important for solar energy (0.25 to 2.5 μm. A simple addition of the base fluid and nanoparticle extinction coefficients is applied as an approximation of the effective nanofluid extinction coefficient. Comparisons with measured extinction coefficients reveal that the approximation works well with water-based nanofluids containing graphite nanoparticles but less well with metallic nanoparticles and/or oil-based fluids. For the materials used in this study, over 95% of incoming sunlight can be absorbed (in a nanofluid thickness ≥10 cm with extremely low nanoparticle volume fractions - less than 1 × 10-5, or 10 parts per million. Thus, nanofluids could be used to absorb sunlight with a negligible amount of viscosity and/or density (read: pumping power increase.