Sample records for cl optical investigations

  1. Investigation of the Kramers-Kronig analysis - Revised optical constants of AgCl (United States)

    Bauer, R. S.; Spicer, W. E.; White, J. J., III


    White and Straley (1968) have reported room-temperature optical constants for AgCl that exhibit negative, unphysical dips at the band edge. Because Morrison (1961) also obtained such behavior for InAs, InSb, and GaAs, a study is made of the possible sources of this anomaly. An artifact of the experimental reflectance data near this energy is found to be responsible. No defect in the Kramers-Kronig transform or its use is implied, contrary to some suggestions. The corrected optical constants of AgCl were modified by about 10% up to 5 eV, whereas at higher energies they were barely affected. Thus Kramers-Kronig-deduced optical constants that exhibit unusual structure are not affected by this structure at other energies. The new AgCl results are presented, and assignments are briefly discussed.

  2. Theoretical and experimental investigations of optical, structural and electronic properties of the lower-dimensional hybrid [NH3-(CH2)10-NH3]ZnCl4 (United States)

    El Mrabet, R.; Kassou, S.; Tahiri, O.; Belaaraj, A.; Guionneau, P.


    In the current study, a combination between theoretical and experimental studies has been made for the hybrid perovskite [NH3-(CH2)10-NH3]ZnCl4. The density functional theory (DFT) was performed to investigate structural and electronic properties of the tilted compound. A local approximation (LDA) and semi-local approach (GGA) were employed. The results are obtained using, respectively, the local exchange correlation functional of Perdew-Wang 92 (PW92) and semi local functional of Perdew-Burke-Ernzerhof (PBE). The optimized cell parameters are in good agreement with the experimental results. Electronic properties have been studied through the calculation of band structures and density of state (DOS), while structural properties are investigated by geometry optimization of the cell. Fritz-Haber-Institute (FHI) pseudopotentials were employed to perform all calculations. The optical diffuse reflectance spectra was mesured and applied to deduce the refractive index ( n), the extinction coefficient ( k), the absorption coefficient (α), the real and imaginary dielectric permittivity parts (ɛr,ɛi)) and the optical band gap energy Eg. The optical band gap energy value shows good consistent with that obtained from DFT calculations and reveals the insulating behavior of the material.

  3. The effect of FeCl{sub 3} on the optical constants and optical band gap of MBZMA-co-MMA polymer thin films

    Energy Technology Data Exchange (ETDEWEB)

    Yakuphanoglu, F. [Department of Physics, Faculty of Arts and Sciences, Firat University, 23169 Elazig (Turkey)]. E-mail:; Barim, G. [Department of Chemistry, Faculty of Arts and Sciences, Firat University, 23169 Elazig (Turkey); Erol, I. [Department of Chemistry, Faculty of Arts and Sciences, Afyon Kocatepe University, Afyon (Turkey)


    The effects of the FeCl{sub 3} dopant on the optical constants and optical band gap of the methylbenzyl methacrylate (MBZMA)-co-methyl-methacrylate (MMA) polymer thin films have been investigated by the optical characterization. The optical constants of the thin films are changed with FeCl{sub 3} dopant. The refractive index dispersion curves of the thin films are fitted by Cauchy-Sellmeier model and dispersion parameters (a {sub 1} and n {sub 0}) change with FeCl{sub 3} dopant. The magnitude of the refractive index increases with increasing FeCl{sub 3} dopant. The electric susceptibility of the thin film materials was calculated and the electric susceptibility increases with FeCl{sub 3} content. The optical band gap values of the thin films were determined. The obtained band gap values are decreased with FeCl{sub 3} dopant. The FeCl{sub 3} dopant changes the width of localized states in the optical band gaps of the thin films. The optical band E {sub g} of the thin films changes from 3.52 to 3.05 eV with increasing FeCl{sub 3} dopant, while the width of localized states in optical band gap changes from 1101.47 to 596.3 meV. It is concluded that the optical constants and optical band gap of the MBZMA-co-MMA polymer thin films change by the FeCl{sub 3} dopant.

  4. Microstructural, optical and electrical properties of Cl-doped CdTe single crystals

    Directory of Open Access Journals (Sweden)

    Choi Hyojeong


    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.

  5. Investigation of Optical Fibers for Nonlinear Optics. (United States)


    Northwestern University, 1970. Experience Dr. Harrington has 13 years of research experi- ence in the area of optical properties of solids . Since joining...dynamics, and optical properties of solids . 34 34I ANTONIO C. PASTOR, Member of the Technical Staff, Optical Physics Department, Hughes Research

  6. Optical properties of the Bi+ center in KAlCl4

    CERN Document Server

    Veber, A A; Usovich, O V; Fattakhova, Z T; Haula, E V; Korchak, V N; Trusov, L A; Kazin, P E; Sulimov, V B; Tsvetkov, V B


    Temperature behavior of the Bi+ center emission, excitation bands and luminescence decay law in KAlCl4 crystal are investigated. Abrupt changes of the monocation optical properties are observed at phase transitions of the host. The observed optical transitions are assigned to the specific energy states of Bi+ ion. It is shown that two thermalized levels are responsible for the luminescence. The experimental temperature behavior of the emission and excitation bands are in agreement with theory of electron-phonon interaction of impurity centers in solids; the effective-phonon frequencies and Huang-Rhys parameters are estimated. The configuration coordinate diagram is determined for the Bi+ center in KAlCl4 crystal.

  7. Electron and electron-phonon effects in quasi-two-dimensional molecular conductor theta-(BETS) sub 4 HgBr sub 4 (C sub 6 H sub 5 Cl): optical investigations at 300-15 K

    CERN Document Server

    Vlasova, R M; Petrov, B V; Semkin, N D; Zhilyaeva, E I; Bogdanova, O A; Lyubovskaya, R N; Graja, A


    One studied the polarized spectra of reflection and spectra of optical transmission of theta-(BETS) sub 4 HgBr sub 4 (C sub 6 H sub 5 Cl) quasi-two-dimensional molecular conductor within 700-6500 cm sup - sup 1 range under 300-15 K temperatures and within 9000-40000 cm sup - sup 1 under 300 K for two principal directions within crystal plane parallel to conducting layers of BETS molecules. Under 300 K within IR region the spectra are characterized by the intensive essential peculiarities (1200-1400 cm sup - sup 1) caused by electron-oscillation coupling (EOC). At temperature drop within 180-80 K range one observes in the spectra a Lorentz term with omega sub t = 2900 cm sup - sup 1 and three extra bands within 800-1180 cm sup - sup 1 region caused by EOC. The derived results are indicative of unstable structural distortions along two principal directions in a crystal followed by formation of a charge density comparable wave

  8. Influence of Air Annealing and Gamma Ray Irradiation on the Optical Properties of Cl16FePc Thin Films

    Directory of Open Access Journals (Sweden)

    Raji Koshy


    Full Text Available Metal phthalocyanines are one of the most promising candidates to be used in the fabrication of such devices. Among various phthalocyanines, Iron Hexadecachloro Phthalocyanine (Cl16FePc has received less attention. Basic characteristics of Cl16FePc are not reported in literature. Hexadecacholoro phthalocyanines have attracted interest as possible n-type organic semiconductor with high electron mobility and good stability characteristics. In the present work we investigate the optical band gap of the Cl16FePc thin films from the optical absorption spectrum as a function of air annealing temperatures and their suitability for the fabrication of molecular electronic devices. Some optical properties of the samples were studied as a function of γ-radiation doses also. Optical transition is found to be of direct type and optical band gaps are determined by analyzing the absorption spectrum. Vacuum sublimed thin films of Iron hexadecachloro phthalocyanine were prepared at room temperature onto glass substrates at a base pressure of 10-5 Torr on precleaned glass substrates using Hind Hivac 12A4 coating plant. The optical energy band gap Eg were calculated. The mechanism of optical absorption follow the rule of direct transition. In the present paper we also report refractive index, real and imaginary parts of optical dielectric constant etc. from the reflectance measurements.

  9. MBiO{sub 2}Cl (M=Sr, Ba) as novel photocatalysts: Synthesis, optical property and photocatalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Hongwei, E-mail:; Wang, Shuobo; Zhang, Yihe, E-mail:; Han, Xu


    Novel quaternary photocatalysts MBiO{sub 2}Cl (M=Sr, Ba) have been successfully developed for efficient photodecomposition of RhB. Their photocatalytic mechanism was also investigated. - Highlights: • Two Bi-based compounds SrBiO{sub 2}Cl and BaBiO{sub 2}Cl were explored as photocatalysts. • They were successfully synthesized by a solid-state reaction. • RhB can be effectively photodecomposed by SrBiO{sub 2}Cl and BaBiO{sub 2}Cl under UV light. • ·OH radicals serving as active species play important roles in degradation process. - Abstract: Two Bi-based compounds SrBiO{sub 2}Cl and BaBiO{sub 2}Cl were successfully synthesized by a solid-state reaction and investigated as new photocatalysts for the first time. Their microstructures and optical properties were characterized by XRD, SEM and DRS. The band gaps of SrBiO{sub 2}Cl and BaBiO{sub 2}Cl were separately determined to be 3.52 and 3.71 eV, and their E{sub CB} and E{sub VB} were also estimated. The photocatalytic activities of the as-prepared samples were evaluated by photodecomposition of rhodamine B (RhB) in aqueous solution. The results revealed that both SrBiO{sub 2}Cl and BaBiO{sub 2}Cl can be used as effective photocatalysts under UV irradiation, and SrBiO{sub 2}Cl exhibits a higher photocatalytic activity than BaBiO{sub 2}Cl, which was also verified by the PL spectra. Terephthalic acid photoluminescence probing technique (TA-PL) demonstrated that ·OH radicals serving as active species play an important role in photooxidative degradation of RhB over SrBiO{sub 2}Cl and BaBiO{sub 2}Cl. Moreover, a larger amount of ·OH radicals generation was observed over SrBiO{sub 2}Cl, which is in agreement with its higher photocatalytic activity.

  10. Investigation on Growth and Optical Properties of LVCC Single Crystals

    Directory of Open Access Journals (Sweden)

    N. Sheen Kumar


    Full Text Available L-valine cadmium chloride (LVCC single crystals were grown by slow evaporation technique with different concentrations (0.25, 0.5, 0.75 and 1.0 mole of CdCl2. All the grown crystals were subjected to single crystal X-ray diffraction analysis. Solid state parameters were calculated for the grown crystals. The optical properties of the crystals were investigated by UV-Vis. absorption spectroscopy. The results revealed that, the wider bandgap and large transparency in the visible region along with higher polarizability of the grown crystals are highly useful in optoelectronic devices. Also according to our needs, one can tune the optical and electrical properties of LVCC crystals by adjusting the concentration of CdCl2 in LVCC.

  11. Optical properties of NbCl5 and ZnMg intercalated graphite compounds (United States)

    Jung, Eilho; Lee, Seokbae; Roh, Seulki; Meng, Xiuqing; Tongay, Sefaattin; Kang, Jihoon; Park, Tuson; Hwang, Jungseek


    We studied NbCl5 and ZnMg alloy intercalated graphite compounds using an optical spectroscopy technique. These intercalated metallic graphite samples were quite challenging to obtain optical reflectance spectra since they were not flat and quite thin. By using both a new method and an in situ gold evaporation technique we were able to obtain reliable reflectance spectra of our samples in the far and mid infrared range (80-7000 cm-1). We extracted the optical constants including the optical conductivity and the dielectric function from the measured reflectance spectra using a Kramers-Kronig analysis. We also extracted the dc conductivity and the plasma frequencies from the optical conductivity and dielectric functions. NbCl5 intercalated graphite samples show similar optical conductivity spectra as bare highly oriented pyrolytic graphite even though there are some differences in detail. ZnMg intercalated samples show significantly different optical conductivity spectra from the bare graphite. Optical spectroscopy is one of the most reliable experimental techniques to obtain the electronic band structures of materials. The obtained optical conductivities support the recent theoretically calculated electronic band structures of NbCl5 and ZnMg intercalated graphite compounds. Our results also provide important information of electronic structures and charge carrier properties of these two new intercalated materials for applications.

  12. Optical properties and electronic structure of BiTeCl and BiTeBr compounds (United States)

    Makhnev, A. A.; Nomerovannaya, L. V.; Kuznetsova, T. V.; Tereshchenko, O. E.; Kokh, K. A.


    Optical properties of BiTeCl and BiTeBr compounds with a strong Rashba spin-orbit coupling are studied in the 0.08-5.0 eV range using the optical ellipsometry method. Fundamental characteristics of the electronic structure are obtained. Similarly to BiTeI, spectra of the imaginary part of dielectric permittivity constant ɛ2( E) in the energy interval between the plasma edge and the threshold of an intense interband absorption (0.7 eV in BiTeCl and 0.6 eV in BiTeBr) display a fine structure of electronic transitions at 0.25 and 0.55 eV in BiTeCl and 0.20 and 0.50 eV in BiTeBr. These features are assigned to electronic transitions between the bulk conduction zones split by the Rashba spin-orbit interaction. The parameters of the electronic structure of BiTeCl and BiTeBr are compared with the BiTeI compound that was studied earlier. In the BiTeCl-BiTeBr-BiTeI row, the absorption edge and main features of the fundamental absorption exhibit a shift to low energies.

  13. Phase transition and optical properties of CaCl2 under high pressure by ab initio pseudopotential plane-wave calculations (United States)

    Liu, Y. H.; Ma, Y. M.; He, Z.; Cui, T.; Liu, B. B.; Zou, G. T.


    We present a detailed investigation of CaCl2 under high pressure in CaCl2 (Pnnm,Z = 2) and α-PbO2 (Pbcn, Z = 4) phases, respectively. Theoretical calculations are performed by using the ab initio pseudopotential plane-wave method based on the density functional method. We estimate the transition pressure between the two phases by the crossing point of their enthalpies, which are equivalent to the Gibbs free energy at zero temperature, after optimizing the structures under high pressure. Our results show that the transition happens at about 2.9 GPa, which is in agreement with the experimental data. We calculate the structural parameters, charge transfers, bond structures, density of states and optical properties. The calculated results show that there are no charge transfers in CaCl2 structure under high pressure. It is found that the transitions from the Cl 3p to Ca 4s and Cl 3s to Ca 3p orbitals contribute mainly to the dielectric function. The optical properties of CaCl2 (Pnnm, Z = 2) do not vary much under pressure. However, some of the dispersion curves of optical constants in the α-PbO2 (Pbcn, Z = 4) phase are changed significantly under pressure.

  14. Phase transition and optical properties of CaCl{sub 2} under high pressure by ab initio pseudopotential plane-wave calculations

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Y H; Ma, Y M; He, Z; Cui, T; Liu, B B; Zou, G T [National Lab of Superhard Materials, Jilin University, Changchun 130012 (China)


    We present a detailed investigation of CaCl{sub 2} under high pressure in CaCl{sub 2} (Pnnm,Z = 2) and {alpha}-PbO{sub 2} (Pbcn, Z = 4) phases, respectively. Theoretical calculations are performed by using the ab initio pseudopotential plane-wave method based on the density functional method. We estimate the transition pressure between the two phases by the crossing point of their enthalpies, which are equivalent to the Gibbs free energy at zero temperature, after optimizing the structures under high pressure. Our results show that the transition happens at about 2.9 GPa, which is in agreement with the experimental data. We calculate the structural parameters, charge transfers, bond structures, density of states and optical properties. The calculated results show that there are no charge transfers in CaCl{sub 2} structure under high pressure. It is found that the transitions from the Cl 3p to Ca 4s and Cl 3s to Ca 3p orbitals contribute mainly to the dielectric function. The optical properties of CaCl{sub 2} (Pnnm, Z = 2) do not vary much under pressure. However, some of the dispersion curves of optical constants in the {alpha}-PbO{sub 2} (Pbcn, Z = 4) phase are changed significantly under pressure.

  15. In-vivo optical investigation of psoriasis (United States)

    Kapsokalyvas, Dimitrios; Cicchi, Riccardo; Bruscino, Nicola; Alfieri, Domenico; Massi, Daniela; Lotti, Torello; Pavone, Francesco S.


    Psoriasis is an autoimmune disease of the skin characterized by hyperkeratosis, hyperproliferation of the epidermis, inflammatory cell accumulation and increased dilatation of dermal papillary blood vessels. Cases of psoriasis were investigated in vivo with optical means in order to evaluate the potential of in vivo optical biopsy. A Polarization Multispectral Dermoscope was employed for the macroscopic observation. Features such as the 'dotted' blood vessels pattern was observed with high contrast. The average size of dot vessels in Psoriasis was measured to be 974 μm2 which is much higher compared to healthy skin. High resolution image sections of the epidermis and the dermis were produced with a custom made Multiphoton Microscope. Imaging extended from the surface of the lesion down to the papillary dermis, at a depth of 200 μm. In the epidermis, a characteristic morphology of the stratum corneum found only in Psoriasis was revealed. Additionally, the cytoplasmic area of the cells in the stratum spinosum layer was found to be smaller than normal. In the dermis the morphological features were more pronounced, where the elongated dermal papillae dominated the papillary layer. Their length exceeds 100μm, which is a far greater value compared to that of healthy skin. These in vivo observations are consistent with the ex vivo histopathological observations, supporting both the applicability and potentiality of multispectral dermoscopy and multiphoton microscopy in the field of in vivo optical investigation and biopsy of skin.

  16. Optical probe of Heisenberg-Kitaev magnetism in α -RuCl3 (United States)

    Sandilands, Luke J.; Sohn, C. H.; Park, H. J.; Kim, So Yeun; Kim, K. W.; Sears, Jennifer A.; Kim, Young-June; Noh, Tae Won


    We report a temperature-dependent optical spectroscopic study of the Heisenberg-Kitaev magnet α -RuCl3 . Our measurements reveal anomalies in the optical response near the magnetic ordering temperature. At higher temperatures, we observe a redistribution of spectral weight over a broad energy range that is associated with nearest-neighbor spin-spin correlations. This finding is consistent with highly frustrated magnetic interactions and in agreement with theoretical expectations for this class of material. The optical data also reveal significant electron-hole interaction effects, including a bound excitonic state. These results demonstrate a clear coupling between charge and spin degrees of freedom and provide insight into the properties of thermally disordered Heisenberg-Kitaev magnets.

  17. Electronic structure, elastic anisotropy, thermal conductivity and optical properties of calcium apatite Ca{sub 5}(PO{sub 4}){sub 3}X (X = F, Cl or Br)

    Energy Technology Data Exchange (ETDEWEB)

    Li, Cheng-Xiu [Kunming University of Science and Technology, Kunming 650093 (China); Institute of Multipurpose Utilization of Mineral Resources, Chinese Academy of Geological Sciences, Chengdu 610041 (China); Research Center of Multipurpose Utilization of Metal Mineral Resources of China Geological Survey, Chengdu 610041 (China); Duan, Yong-Hua, E-mail: [Kunming University of Science and Technology, Kunming 650093 (China); Hu, Wen-Cheng [School of Mechanical and Electrical Engineering, Nanchang University, Nanchang 330031 (China)


    Highlights: • The degree of elastic anisotropy is ordered as follows BrA > ClA > FA. • The thermal conductivity in (112{sup ¯}0) plane is smaller than in (0 0 0 1) plane. • The refractive indexes for FA, ClA and BrA are 1.17, 1.19 and 1.21, respectively. - Abstract: The density-functional theory with the generalized gradient approximation was performed to investigate the structural properties, phase stability, electronic structure, elastic properties, and optical properties of selected Ca{sub 5}(PO{sub 3}){sub 4}F (FA), Ca{sub 5}(PO{sub 3}){sub 4}Cl (ClA) and Ca{sub 5}(PO{sub 3}){sub 4}Br (BrA). Results of formation enthalpies show that FA is regarded as the most stable one in these apatites. The electronic structures including band structure, density of states and Mulliken analysis have been discussed. The predicted elastic moduli results indicate that the degree of elastic anisotropy is ordered as follows BrA > ClA > FA. By using the Clarke’s model and Cahill’s model, the thermal conductivities and the anisotropy in thermal conductivity have also been analyzed. Optic properties results indicate that the refractive indexes n for FA, ClA and BrA are 1.17, 1.19 and 1.21, respectively.

  18. Optically stimulated luminescence of natural NaCl mineral from Dead Sea exposed to gamma radiation

    Energy Technology Data Exchange (ETDEWEB)

    Roman L, J.; Cruz Z, E. [UNAM, Instituto de Ciencias Nucleares, Ciudad Universitaria, 04510 Ciudad de Mexico (Mexico); Pina L, Y. I. [UNAM, Facultad de Ciencias, Ciudad Universitaria, 04510 Ciudad de Mexico (Mexico); Marcazzo, J., E-mail: [Instituto de Fisica Arroyo Seco - UNICEN, Pinto 399, 7000 Tandil (Argentina)


    Luminescence properties such as radioluminescence, thermoluminescence and optically stimulated luminescence have been studied on natural sodium chloride (NaCl) for dosimetric purposes in retrospective dosimetry (Timar-Gabor et al., 2013; Druzhyna et al., 2016). In this work, the optically stimulated luminescence (Cw-OSL) emissions of natural salt minerals, collected from Dead Sea in summer of 2015, were studied. The Cw-OSL dose response of natural salt was analyzed in the range between 0.2 and 10 Gy gamma dose of {sup 60}Co. Samples exposed at 3 Gy exhibited good repeatability with a variation coefficient of 4.6%. The thermal stability of the Cw-OSL response was analyzed to different temperatures from 50 up to 250 degrees Celsius using a heating rate of 5 degrees Celsius. The results showed that the natural Dead Sea salt minerals could be applied as natural dosimeter of gamma radiation. (Author)

  19. Analytical investigation of AlCl[3]/SO[2]Cl[2] catholyte materials for secondary fuze reserve batteries.

    Energy Technology Data Exchange (ETDEWEB)

    Butler, Paul Charles; Rodriguez, Mark Andrew; Segall, Judith M.; Malizia, Louis A., Jr.; Cherry, Brian Ray; Andrews, Nicholas L.; Clark, Nancy H.; Alam, Todd Michael; Ingersoll, David T.; Tallant, David Robert; Simpson, Regina Lynn; Boyle, Timothy J.; Garcia, Manuel Joseph


    Exploration of the fundamental chemical behavior of the AlCl{sub 3}/SO{sub 2}Cl{sub 2} catholyte system for the ARDEC Self-Destruct Fuze Reserve Battery Project under accelerated aging conditions was completed using a variety of analytical tools. Four different molecular species were identified in this solution, three of which are major. The relative concentrations of the molecular species formed were found to depend on aging time, initial concentrations, and storage temperature, with each variable affecting the kinetics and thermodynamics of this complex reaction system. We also evaluated the effect of water on the system, and determined that it does not play a role in dictating the observed molecular species present in solution. The first Al-containing species formed was identified as the dimer [Al({mu}-Cl)Cl{sub 2}]{sub 2}, and was found to be in equilibrium with the monomer, AlCl{sub 3}. The second species formed in the reaction scheme was identified by single crystal X-ray diffraction studies as [Cl{sub 2}Al({mu}-O{sub 2}SCl)]{sub 2} (I), a scrambled AlCl{sub 3}{center_dot}SO{sub 2} adduct. The SO{sub 2}(g) present, as well as CL{sub 2}(g), was formed through decomposition of SO{sub 2}CL{sub 2}. The SO{sub 2}(g) generated was readily consumed by AlCl{sub 3} to form the adduct 1 which was experimentally verified when 1 was also isolated from the reaction of SO{sub 2}(g) and AlCl {sub 3}. The third species found was tentatively identified as a compound having the general formula {l_brace}[Al(O)Cl{sub 2}][OSCl{sub 2}]{r_brace}{sub n}. This was based on {sup 27}Al NMR data that revealed a species with tetrahedrally coordinated Al metal centers with increased oxygen coordination and the fact that the precipitate, or gel, that forms over time was shown by Raman spectroscopic studies to possess a component that is consistent with SOCl{sub 2}. The precursor to the precipitate should have similar constituents, thus the assignment of {l_brace}[Al(O)Cl{sub 2}][OSCl{sub 2

  20. Optical investigation of electromagnetic fuel atomizers (United States)

    Suciu, Cornel; Beniuga, Marius


    The devices that ensure atomization of fluids (injectors and atomizers) are largely employed in contemporary technology. Injectors play a very important part in the functioning of various systems based on combustion of liquid fuels, such as internal combustion engines and turbines, jet engines, furnaces etc. During operation, these devices are subjected to important pressures and need to work within very strict parameters. It is therefore important to have very precise active surfaces. The present work aimed to investigate such devices after certain degrees of usage in order to verify the evolution of surface micro-characteristics and their influence upon operating parameters. In order to achieve the abovementioned purpose, an optical evaluation of the surface was conducted using laser profilometry. Surface measurements were conducted on several injectors, after various degrees of usage, by aid of a laser profilometer equipped with a confocal sensor that has a vertical working range of 13mm and a resolution of 1μm1. After the surface micro-topography was measured, 3D and 2D representations, as well as individual profiles of the active surfaces, were analyzed and the significant parameters were determined. Surface wear and presence of combustion residues was analyzed in terms of its influence upon operating conditions.

  1. PEO-LiClO4-ZSM5 composite polymer electrolyte (IV): Polarized optical microscopy study

    Institute of Scientific and Technical Information of China (English)

    XI Jingyu; QIU Xinping; ZHU Wentao; CHEN Liquan


    Polarized optical microscopy (POM) results show that ZSM5 has great influence on both the nucleation stage and the growth stage of PEO spherulites. Part of ZSM5 particles can act as the nucleus of PEO spherulites and thus increase the amount of PEO spherulites. On the other hand, ZSM5 can restrain the recrystallization tendency of PEO chains through Lewis acid-base interaction and hence decrease the growth speed of PEO spherulites. The increasing amount of PEO spherulites, decreasing size of PEO spherulites, and the incomplete crystallization are all beneficial for creating more continuous amorphous phases of PEO, which is very important for the transporting of Li+ ions. An adequate amount of ZSM5 can enhance the room temperature ionic conductivity of PEO-LiClO4 based polymer electrolyte for more than two magnitudes.

  2. X-ray excited optical luminescence studies on the system Ba (, =F, Cl, Br, I)

    Indian Academy of Sciences (India)

    K Govinda Rajan; A Jestin Lenus


    The present paper reports the experimental observations on the x-ray excited optical luminescence (XEOL) along with the afterglow and colour center features found for the barium salts, represented by the formula, Ba, where and are the halides. The system thus consists of four dihalides (BaF2, . . . ,BaI2) and six mixed halides (BaFCl,. . . ,BaBrI). To start with, it was found that on two of the binary halides of barium, BaClI and BaBrI, no literature exists, and so these were prepared for the first time and their crystal structures were determined. An x-ray generator of 3-kW rating was next coupled to a spectrometer via a high throughput fiberoptic sensor for recording the luminescence spectra under x-irradiation. Also presented in this paper are the observations on the Ba compounds in which about 0.1 mole% of Eu2+ was doped, in order to study the efficiency between the prompt luminescence and the photostimulated luminescence in these compounds. The crystal structure varies from fluorite (BaF2), to matlockite (BaF) and finally to orthorhombic (BaCl2, . . .,BaBrI) for these compounds. Hence searching for systematics and empirical relations in the observed XEOL behaviour of these compounds is still a challenging problem.

  3. Pd+ ions in NaCl single crystal: EPR and optical studies (United States)

    Badalyan, A. G.; Polak, K.; Rosa, J.


    EPR and optical absorption of Pd centres in as grown NaCl single crystal are reported. The EPR spectra show that palladium forms the Pd+ centre with d(x2-y2) wave function in the ground state. This centre formation and the accompanying distortion give rise to a superhyperfine interaction of the Pd+ ion with the nuclei of the four Cl- ligands in the plane perpendicular to the C-4 Symmetry axis. The results of the fitting of axial spin Hamiltonian parameters to the experimentally observed spectra give the following values at 12 K: g(parallel to) =2.85, g(perpendicular to) congruent to 2.15, A(parallel to) 29.8 x 10(-4)cm(-1), A(perpendicular to) = 5.9 x 10(-4)cm(-1). When the temperature increases, lines are getting broader, their amplitude decreases and a single line with g-value of g = 2.38 at g = 1/3(g(parallel to)+ 2g(perpendicular to)) appears, which demonstrates the known Jahn-Teller behaviour of d(9) ions EPR spectra.

  4. Honeywell optical investigations on FLASH program (United States)

    O'Rourke, Ken; Peterson, Eric; Yount, Larry


    The increasing performance and reduction of life cycle cost requirements placed on commercial and military transport aircraft are resulting in more complex, highly integrated aircraft control and management systems. The use of fiber optic data transmission media can make significant contributions in achieving these performance and cost goals. The Honeywell portion of Task 2A on the Fly-by-Light Advanced System Hardware (FLASH) program is evaluating a Primary Flight Control System (PFCS) using pilot and copilot inputs from Active Hand Controllers (AHC) which are optically linked to the primary flight Control Computers (PFCC). Customer involvement is an important element of the Task 2A activity. Establishing customer requirements and perspectives on productization of systems developed under FLASH are key to future product success. The Honeywell elements of the PFCS demonstrator provide a command path that is optically interfaced from crew inputs to commands of distributed, smart actuation subsystems commands. Optical communication architectures are implemented using several protocols including the new AS-1773A 20 Mbps data bus standard. The interconnecting fiber optic cable plant is provided by our Task 1A teammate McDonnell Douglas Aerospace (West). Fiber optic cable plant fabrication uses processed, tools and materials reflecting necessary advances in manufacturing required to make fly-by-light avionics systems marketable.

  5. Spectroscopic investigations of Np(V/VI) redox speciation in hyperalkaline TMA-(OH, Cl) solutions

    Energy Technology Data Exchange (ETDEWEB)

    Gaona, X.; Dardenne, K.; Liu, X.; Rothe, J.; Denecke, M.A.; Altmaier, M. [Karlsruhe Institute of Technology (KIT), Karlsruhe (Germany). Inst. fuer Nukleare Entsorgung; Tits, J.; Wieland, E. [Paul Scherrer Institut (PSI), Villigen (Switzerland). Lab. for Waste Management


    The redox chemistry of Np(V/VI) was investigated in {proportional_to} 0.6 M tetramethylammonium hydroxide/chloride (TMA-(OH, Cl)) solutions with 9 {<=} -log [H{sup +}] {<=} 13.5. Redox conditions were defined by the absence or presence of ClO{sup -} as oxidizing agent (Na-salt, 5 x 10{sup -3} M and 5 x 10{sup -2} M). The high total Np concentration ([Np]{sub tot} {proportional_to} 2 x 10{sup -3} M) led to the precipitation of solid phases in some of the samples. The carbonate concentration (as impurity of TMA-OH) was 2-3 x 10{sup -3} M. UV-vis/NIR spectra obtained from the supernatant in TMA-(OH, Cl) solutions and absence of ClO{sup -} showed clear Np(V) features, identified as NpO{sub 2}{sup +}, NpO{sub 2}CO{sub 3}{sup -} and (NpO{sub 2}){sub x}(CO{sub 3}){sub y}(OH){sub z}{sup x-2y-z}. No NIR features were observed within 800 nm {<=} {lambda} {<=} 1300 nm for samples with ClO{sup -}. XANES edge energies and features of these samples confirmed the predominance of Np(V) in the absence of ClO{sup -} and Np(VI) in the presence of ClO{sup -}, by comparison to XANES reference spectra of Np(III/IV/V/VI) prepared within the present work by in-situ electrolysis. A similar Np redox distribution was observed for the solid phases based on XANES and EXAFS measurements. EXAFS spectra indicative of Np{sup V}O{sub 2}OH(s) and Np{sup VI}O{sub 3} . xH{sub 2}O(s) were obtained for samples in absence and presence of ClO{sup -}, respectively. The formation of a Na-Np(VI) phase in 5 x 10{sup -2} M ClO{sup -} and -log [H{sup +}] {proportional_to} 12 was also indicated from the EXAFS, chemical analysis and SEM-EDS. These results indicate that Np(VI) aqueous species and solid compounds prevail far below the oxidation border of water in alkaline solutions and also far below the E{sub H} border calculated with the current NEA data selection [1]. These observations are further supported by correlations of literature thermodynamic data for actinides (U, Np, Pu and Am), which predict the

  6. Synthesis, crystal and electronic structure, and optical property of the pentanary chalcohalide Ba3KSb4S9Cl (United States)

    Zhao, Hua-Jun; Liu, Peng-Fei


    The pentanary chalcohalide Ba3KSb4S9Cl has been prepared from stoichiometric mixtures of KCl, Ba, Sb, and S in an evacuated silica tube, which is the first example of chalcohalides in the pentanary A/Ae/Sb/Q/X (A=alkali metal; Ae=alkaline-earth metal; Q=S, Se, Te; X=F, Cl, Br, I) system. This material crystallize in the Pnnm space group and its new structure type comprises one-dimensional (1D) [Sb3S7]5- chains running down the [001] direction separated by isolated dimeric Sb2S4 polyhedra, Ba2+, K+, and Cl-, respectively. The optical gap of 1.99 eV for Ba3KSb4S9Cl was deduced from the UV/vis reflectance spectroscopy and DFT study indicates a indirect band gap with an electronic transfer excitation of S 3p to Sb 5p orbital electrons.

  7. Investigation of Nonlinear Optical Properties of Semiconductors. (United States)


    optical studies of InSb NI. W. Goodwin" and D. G. Seiler Center jo .4pphed Quurntm Electronics, Department of Phytics , North 1exu.% State Unuvpieroty...lnSb, in zero magnetic field, is that of Pidgeon anJ data, aside from two-photon absorption, could be ab- co-workers,’ who give references to other

  8. Optical coherence tomography investigations of ceramic lumineers (United States)

    Fernandes, Luana O.; Graça, Natalia D. R. L.; Melo, Luciana S. A.; Silva, Claudio H. V.; Gomes, Anderson S. L.


    Lumineers are veneer laminates used as an alternative for aesthetic dental solutions of the highest quality, but the only current means of its performance assessment is visual inspection. The objective of this study was to use the Optical Coherence Tomography (OCT) technique working in spectral domain to analyze in vivo in a single patient, 14 lumineers 180 days after cementation. It was possible to observe images in various kinds of changes in the cementing line and the laminate. It was concluded that the OCT is an effective and promising method to clinical evaluation of the cementing line in lumineers.

  9. Esterification of Oleic Acid for Biodiesel Production Catalyzed by SnCl2: A Kinetic Investigation

    Directory of Open Access Journals (Sweden)

    Marcio J. da Silva


    Full Text Available The production of biodiesel from low-cost raw materials which generally contain high amounts of free fatty acids (FFAs is a valuable alternative that would make their production costs more competitive than petroleum-derived fuel. Currently, the production of biodiesel from this kind of raw materials comprises a two-stage process, which requires an initial acid-catalyzed esterification of the FFA, followed by a basecatalyzed transesterification of the triglycerides. Commonly, the acid H2SO4 is the catalyst on the first step of this process. It must be said, however, that major drawbacks such as substantial reactor corrosion and the great generation of wastes, including the salts formed due to neutralization of the mineral acid, are negative and virtually unsurmountable aspects of this protocol. In this paper, tin(II chloride dihydrate (SnCl2·2H2O, an inexpensive Lewis acid, was evaluated as catalyst on the ethanolysis of oleic acid, which is the major component of several fat and vegetable oils feedstocks. Tin chloride efficiently promoted the conversion of oleic acid into ethyl oleate in ethanol solution and in soybean oil samples, under mild reaction conditions. The SnCl2 catalyst was shown to be as active as the mineral acid H2SO4. Its use has relevant advantages in comparison to mineral acids catalysts, such as less corrosion of the reactors and as well as avoiding the unnecessary neutralization of products. Herein, the effect of the principal parameters of reaction on the yield and rate of ethyl oleate production has been investigated. Kinetic measurements revealed that the esterification of oleic acid catalyzed by SnCl2·2H2O is first-order in relation to both FFAs and catalyst concentration. Experimentally, it was verified that the energy of activation of the esterification reaction of oleic acid catalyzed by SnCl2 was very close those reported for H2SO4.

  10. Formation of KrCl * and ArCl * molecules and radiative lifetimes of their B states investigated with selective synchrotron radiation excitation (United States)

    Castex, M. C.; Le Calvé, J.; Haaks, D.; Jordan, B.; Zimmerer, G.


    Monochromatic pulsed VUV excitation of Cl 2 or inert gas atoms in Cl 2 doped Kr and Ar leads to formation of KrCl * and ArCl *. The radiative lifetimes of the B states (KrCl * 19 ns, ArCl * 9 ns) and rate constants for excimer formation, quenching and collisional mixing of B and C states are given. The radiative lifetime and the quenching rate increase with vibrational excitation of the B state (KrCl *).

  11. Preparation and Structural Investigation of CuCl2 Graphite Intercalation Compounds

    Institute of Scientific and Technical Information of China (English)

    BIN Xiaopei; CHEN Jiazang; CAO Hong; MA Enbao; WANG Xuehua; YUAN Jizhu


    Superfine graphite powder was prepared by ball-milling exfoliated graphite containing anhydrous CuCl2 in planetary ball milling systems. Nano-scale CuCl2 graphite intercalation compounds were synthesized by heating a mixture of anhydrous CuCl2 and graphite nanosheets.Scanning electron microscopy, energy-dispersive X-ray spectroscopy and high-resolution transmission electron microscopy were performed to characterize the microstructures of stage-1 nano-scale CuCl2 graphite intercalation compounds. The structure and components of the domain wall and core in thenano-scale CuCl2 graphite intercalation compounds are described. The results show that the contentof CuCl2 in the mixture plays a crucial role in the size of the nano-scale CuCl2 graphite intercalation compound.

  12. Investigation on the mechanism and applications of the reaction Cl2+2HBr=2HCl+Br2

    Institute of Scientific and Technical Information of China (English)


    The mechanism of reaction Cl2+2HBr=2HCl+Br2 has been carefully investigated with density functional theory (DFT) at B3LYP/6-311G** level. A series of three-centred and four-cen- tred transition states have been obtained. The activation energy (138.96 and 147.24 kJ/mol, re-spectively) of two bimolecular elementary reactions Cl2+HBr→HCl+BrCl and BrCl+HBr→HCl+Br2 is smaller than the dissociation energy of Cl2, HBr and BrCl, indicating that it is favorable for the title reaction occurring in the bimolecular form. The reaction has been applied to the chemical engi-neering process of recycling Br2 from HBr. Gaseous Cl2 directly reacts with HBr gas, which pro-duces gaseous mixtures containing Br2, and liquid Br2 and HCl are obtained by cooling the mixtures and further separated by absorption with CCl4. The recovery percentage of Br2 is more than 96%, and the Cl2 remaining in liquid Br2 is less than 3.0%. The paper provides a good example of solving the difficult problem in chemical engineering with basic theory.

  13. Optical and microstructural investigations of porous silicon

    Indian Academy of Sciences (India)

    R Prabakaran; R Kesavamoorthy; Alok Singh


    Raman scattering and photoluminescence (PL) measurements on (100) oriented -type crystalline silicon (-Si) and porous silicon (PS) samples were carried out. PS samples were prepared by anodic etching of -Si under the illumination of light for different etching times of 30, 60 and 90 min. Raman scattering from the optical phonon in PS showed the redshift of the phonon frequency, broadening and increased asymmetry of the Raman mode on increasing the etching time. Using the phonon confinement model, the average diameter of Si nanocrystallites has been estimated as 2.9, 2.6 and 2.3 nm for 30, 60 and 90 min samples, respectively. Similar size of Si crystallites has been confirmed from the high resolution transmission electron microscopy (HRTEM). Using 2TO phonon mode intensity, we conjectured that the disordered Si region around the pores present in 30 min PS dissolved on etching for 90 min. The photoluminescence (PL) from PS increased in intensity and blue shifted with etching time from 2.1–2.3 eV. Blue shifting of PL is consistent with quantum confinement of electron in Si nanocrystallites and their sizes are estimated as 2.4, 2.3 and 2.1 nm for 30, 60 and 90 min PS, respectively which are smaller than the Raman estimated sizes due to temperature effect. Unambiguous dominance of quantum confinement effect is reported in these PS samples.

  14. Investigation of Combustion Process Using Fiber Optics. (United States)


    LIF) as demonstrated by Chian and D~aily in a methane burner (Ref. 12) could also be investigated with the use of an additional uv laser illuminating...tutre in Flames Using Laser Induiced F I ores cenIc Spect roscopv of OH"’ App. Opt ics 19, 1963 (1980). 13. A. C. Eckb ret h, ’’ ApplIic at ion ot La ser

  15. Synthesis, structure, spectroscopic investigations, and computational studies of optically pure β-ketoamide (United States)

    Mtat, D.; Touati, R.; Guerfel, T.; Walha, K.; Ben Hassine, B.


    Chemical preparation, X-ray single crystal diffraction, IR and NMR spectroscopic investigations of a novel nonlinear optical organic compound (C17H22NO2Cl) are described. The compound crystallizes in the orthorhombic system with the non-centrosymmetric sp. gr. P212121. In the crystal structure, molecules are interconnected by N-H…O hydrogen bonds forming infinite chains along a axis. The Hirshfeld surface and associated fingerprint plots of the compound are presented to explore the nature of intermolecular interactions and their relative contributions in building the solid-state architecture. The molecular HOMO-LUMO compositions and their respective energy gaps are also drawn to explain the activity of the compound. The first hyperpolarizability βtot of the title compound is determined using DFT calculations. The optical properties are also investigated by UV-Vis absorption spectrum.

  16. CeCl3-CaCl2-MgCl2三元体系相图的研究%Investigation on Phase Diagram of CeCl3-CaCl2-MgCl2 Ternary System

    Institute of Scientific and Technical Information of China (English)

    郑朝贵; 叶于浦; 张晓励; 乔芝郁


    @@至今只见到某些稀土氯化物二元相图的报道,而含稀土的三元熔盐体系相图则研究甚少。据报道,CeCl3-CaCl2-MgCl2体系中相关的三个二元体系均属简单低共熔型。曾重新考察并测定其低共熔点的组成与温度为:CeCl3-MgCl2,54.0wt.%CeCl3(660℃)[1];CeCl3-CaCl2,57.0wt.%CeCl 3(622℃)[2];CaCl2-MgCl2,45.2wt.%MgCl2(609℃)[3]。作为系列研究含稀土氯化物三元相图与探讨其规律[4]的工作之一,本文测定了CeCl 3-CaCl2-MgCl2三元相图。 一、实验方法 MgCl2、CeCl 3和CaCl2分别由MgCl2·6H2O、CeCl3·6H2O和CaCl2·nH2O在干燥的HCl气氛中,逐级充分脱水制得[5]。除CeCl3纯度>99.5%外,其他试剂均为分析纯o CaCl2、MgCl2和CeCl3的熔点分别为:775、713和810℃。 准确配制约150mg样品,在充分干燥气氛中装入石英安瓿,抽空封口后,熔化样品并仔细摇匀,在400℃保温4h,留待差热分析。


    Directory of Open Access Journals (Sweden)

    M. E. Efimov


    Full Text Available Subject of Research. The paper provides comparison of theoretical and experimental research results of directivity pattern of dual fiber optic hydrophone at various acoustic frequencies. Application of multiple fiber optic transducers in fiber optic hydrophone design placed in sensitive arm of the interferometer gives the possibility for increasing the sensitivity of a fiber optic hydrophone without changing the fiber-optic transducers. In the simplest case, such fiber optic hydrophone can be built on the basis of two spatially separated acoustic transducers. However, this diversity inevitably leads to the directivity pattern unevenness of the fiber optic hydrophone at acoustic frequencies which wavelengths are commensurate with the size of the transducers system. Method. Mathematical model has been created and it became the base material for a theoretical study of two acoustic transducers system in Mathcad environment. Directivity pattern was described by a mathematical formula, depending on the frequency of the acoustic impact and the distance between sensors. To confirm the correctness of theoretical research of the directivity pattern, dual fiber optic hydrophone on Bragg gratings was produced and investigated experimentally. It consists of two consequently welded sensitive elements with a 9 cm distance between them. In trials carried out in open water conditions, fiber-optic hydrophone was placed on the rotator and rotated relative to the piezoceramic emitter for 360 degrees. During investigation, the signal from a fiber optic hydrophone has been recorded simultaneously with the rotation. Further, after the data processing in MATLAB, amplitude of the measured phase signal and the directivity pattern of the test sample were estimated. Amplitude estimation of the measured phase signal and directivity pattern creation of the sample was performed at frequencies equal to 1000, 3000 and 8000 Hz. Main Results. Sensitivity of the dual fiber optic

  18. Experimental Investigation of Integrated Optical Intensive Impulse Electric Field Sensors

    Institute of Scientific and Technical Information of China (English)

    SUN Bao; CHEN Fu-Shen


    We design and fabricate an integrated optical electric field sensor with segmented electrode for intensive im-pulse electric field measurement. The integrated optical sensor is based on a Mach-Zehnder interferometer with segmented electrodes. The output/input character of the sensing system is analysed and measured. The max-imal detectable electric field range (-75 kV/m to 245 kV/m) is obtained by analysing the results. As a result, the integrated optics electric field sensing system is suitable for transient intensive electric field measurement investigation.

  19. Preparation of AgCl Nano-Crystal Embedded Tellurite Nonlinear Optical Glasses under Electric Field Accompanied Heat Treatment

    Institute of Scientific and Technical Information of China (English)

    Jian LIN; Wenhai HUANG; Bofang LI; Chong JIN; Changcheng LIU; Shuhua LEI; Zhenrong SUN


    The quantum effect of nano-crystals is an important factor to improve nonlinear optical performance of nano-crystal embedded glasses,while controlling the size distribution and content of nano-crystals in the glass accurately is a key to obtain good quality.The auxiliary direct current electric field,accompanied with heat treatment,was applied on AgCl containing niobic tellurite glass sheet.The nucleation and crystallization of the glass were well controlled under auxiliary electric field.It was found that the average size of AgCl nano-crystal particles in the glass is smaller than that under single heat treatment,and the content of nano-crystals is higher.Therefore the third-order nonlinear optical performance of the glass was increased a lot.The local-area distributed AgCl nano-crystal particles can also be embedded into a glass sheet by using locally applied electric field.

  20. Structural and optical properties of chemically deposited Cd(S–Se) : CdCl2, Sm films

    Indian Academy of Sciences (India)

    R S Singh; S Bhushan


    Results of SEM and XRD studies, optical absorption and photoluminescence (PL) emission spectra and photoconductivity (PC), rise and decay studies are reported for Cd(S–Se) : CdCl2, Sm films prepared by chemical deposition method on glass substrates at 60°C in a water bath. SEM studies show ball-type structures along with voids which are related to layered growth. XRD studies show prominent diffraction lines of CdS and CdSe along with some peaks of CdCl2 and impurity Sm. The values of strain (), grain size () and dislocation density () are evaluated from XRD studies and the nature of crystallinity of the films are discussed. Optical absorption spectra also show the presence of Sm in the lattice. From the results of optical absorption spectra, the band gaps are determined. PL emission spectra of Cd(S–Se) consist of two peaks which are related to the edge emission of CdS and CdSe involving excitons. In Sm-doped emissions corresponding to transitions ${}^{4}G_{5/2}$ to ${}^{6}H_{5/2}$, ${}^{6}H_{7/2}$ and ${}^{6}H_{9/2}$ are observed. Sufficiently high photo current (pc) to dark current (dc) ratios with a maximum value of the order of 106 are also obtained in some special cases. This high photosensitization is related to increase in mobility and life time of carriers due to photo excitation.

  1. TiCl4 Pretreatment and Electrodeposition Time Investigations of ZnO Photoelectrodes Preparation for Dye Sensitized Solar Cells

    Directory of Open Access Journals (Sweden)

    Xiaoping Zou


    Full Text Available TiCl4 pretreatment is used in the fabrication of high performance photoanodes for dyes-sensitized solar cells (DSSCs. In this paper, TiCl4 pretreatment was used on fluorine doped tin oxide (FTO before fabricating ZnO films by electrochemical method. The effects of TiCl4 pretreatment on some important parameters of solar cells, such as short-circuit current (Jsc and filling factor, were investigated. The morphology of ZnO films was changed after TiCl4 pretreatment, which can offer large surface area to absorb much more dyes. When the time of electrodeposition was 3 min, the dyes-sensitized solar cells (DSSCs based on TiCl4 pretreatment ZnO films showed more superior photoelectrochemical performance. The parameters of DSSCs are greatly improved. The DSSC based on ZnO films after TiCl4 pretreatment has a very promising value for fabricating high performance solar cells.

  2. Detailed investigation of Cl-corrosion initiated by deposits formed in biomass-fired boilers. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Frandsen, Flemming J.; Lith, S. van


    The aim was to investigate deposit-induced Cl-corrosion under well-controlled laboratory conditions, simulating the conditions in biomass-fired boilers. This has been done by exposing pieces of superheater tubes, covered by synthetic salts, at temperatures and gas mixtures simulating biomass-fired conditions. The corroded specimens have been studied in detail using a Scanning Electron Microscope (SEM), in order to determine the corrosion rate, and to investigate the chemistry and morphology of the corrosive attack. The project has been divided into four activities: A1: Relationship between the Cl-concentration in the deposit, and the corrosion rate. A2: Influence of cation type (K+ and Na+) on the mobility of Cl in the deposit. A3: Influence of metal temperature on the corrosion rate. A4: Critical evaluation of the existing experience for minimizing corrosion in full-scale boilers firing totally or partly with biomass. (LN)

  3. Scanning probe and optical tweezer investigations of biomolecular interactions

    Energy Technology Data Exchange (ETDEWEB)

    Rigby-Singleton, Shellie


    A complex array of intermolecular forces controls the interactions between and within biological molecules. The desire to empirically explore the fundamental forces has led to the development of several biophysical techniques. Of these, the atomic force microscope (AFM) and the optical tweezers have been employed throughout this thesis to monitor the intermolecular forces involved in biomolecular interactions. The AFM is a well-established force sensing technique capable of measuring biomolecular interactions at a single molecule level. However, its versatility has not been extrapolated to the investigation of a drug-enzyme complex. The energy landscape for the force induced dissociation of the DHFR-methotrexate complex was studied. Revealing an energy barrier to dissociation located {approx}0.3 nm from the bound state. Unfortunately, the AFM has a limited range of accessible loading rates and in order to profile the complete energy landscape alternative force sensing instrumentation should be considered, for example the BFP and optical tweezers. Thus, this thesis outlines the development and construction an optical trap capable of measuring intermolecular forces between biomolecules at the single molecule level. To demonstrate the force sensing abilities of the optical set up, proof of principle measurements were performed which investigate the interactions between proteins and polymer surfaces subjected to varying degrees of argon plasma treatment. Complementary data was gained from measurements performed independently by the AFM. Changes in polymer resistance to proteins as a response to changes in polymer surface chemistry were detected utilising both AFM and optical tweezers measurements. Finally, the AFM and optical tweezers were employed as ultrasensitive biosensors. Single molecule investigations of the antibody-antigen interaction between the cardiac troponin I marker and its complementary antibody, reveals the impact therapeutic concentrations of heparin

  4. C-Cl activation by group IV metal oxides in solid argon matrixes: matrix isolation infrared spectroscopy and theoretical investigations of the reactions of MOx (M = Ti, Zr; x = 1, 2) with CH3Cl. (United States)

    Zhao, Yanying


    Reactions of the ground-state titanium and zirconium monoxide and dioxide molecules with monochloromethane in excess argon matrixes have been investigated in solid argon by infrared absorption spectroscopy and density functional theoretical calculations. The results show that the ground-state MOx (M = Ti, Zr; x = 1, 2) molecules react with CH3Cl to first form the weakly bound MO(CH3Cl) and MO2(CH3Cl) complexes. The MO(CH3Cl) complexes can rearrange to the CH3M(O)Cl isomers with the Cl atom of CH3Cl coordination to the metal center of MO upon UV light irradiation (λ MOx mechanism was interpreted by the calculated potential energy profiles.

  5. SQUID and magneto-optic investigations of flux turbulence

    DEFF Research Database (Denmark)

    Koblischka, M.R.; Johansen, T.H.; Baziljevich, M.


    Instabilities of the critical state ("turbulence") are observed in various high-T-c, single crystals by means of magneto-optic (MO) imaging. Using the same samples as in the MO investigations, we observe for the first time characteristic steps in the magnetic moment measured by means of a SQUID s...

  6. An investigation of aerosol optical properties: Atmospheric implications and influences (United States)

    Penaloza-Murillo, Marcos A.

    An experimental, observational, and theoretical investigation of aerosol optical properties has been made in this work to study their implications and influences on the atmosphere. In the laboratory the scientific and instrumental methodology consisted of three parts, namely, aerosol generation, optical and mass concentration measurements, and computational calculations. In particular the optical properties of ammonium sulfate and caffeine aerosol were derived from measurements made with a transmissometer cell-reciprocal- integrating nephelometer (TCRIN), equipped with a laser beam at 632.8 nm, and by applying a Mie theory computer code The aerosol generators, optical equipment and calibration procedures were reviewed. The aerosol shape and size distribution were studied by means of scanning electron microscopy and the Gumprecht- Sliepcevich/Lipofsky-Green extinction-sedimentation method. In particular the spherical and cylindrical shape were considered. During this investigation, an alternative method for obtaining the optical properties of monodisperse spherical non-absorbing aerosol using a cell-transmissometer, which is based on a linearisation of the Lambert-Beer law, was found. In addition, adapting the TCRIN to electrooptical aerosol studies, the optical properties of a circular-cylindrical aerosol of caffeine were undertaken under the condition of random orientation in relation with the laser beam, and perpendicular orientation to it. A theoretical study was conducted to assess the sensitivity of aerosol to a change of shape under different polarisation modes. The aerosol optical properties, obtained previously in the laboratory, were then used to simulate the direct radiative forcing. The calculations and results were obtained by applying a one- dimensional energy-balance box model. The influence of atmospheric aerosol on the sky brightness due to a total solar eclipse was studied using the photometric and meteorological observations made during the

  7. Theoretical investigation of potential energy surface and bound states for the van der Waals complex Ar–BrCl dimer

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Rui [School of Mathematics and Information Science, North China University of Water Resources and Electric Power, Zhengzhou (China); Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Centre for Magnetic Resonance, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan (China); Li, Song, E-mail: [School of Physics and Optoelectronic Engineering, Yangtze University, Jingzhou (China); Chen, Shan-Jun; Chen, Yan [School of Physics and Optoelectronic Engineering, Yangtze University, Jingzhou (China); Zheng, Li-Min [Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Centre for Magnetic Resonance, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan (China)


    Highlights: • A two-dimensional potential for Ar–BrCl is constructed at the CCSD(T) level. • The PES is characterized by three minima and two saddle points between them. • Bound state calculations were carried out for the complex. - Abstract: The intermolecular potential energy surface (PES) of the ground electronic state for the Ar–BrCl dimer is constructed at the CCSD(T) level with the aug-cc-pVQZ basis set and mid-bond functions. The PES is characterized by three minima and two saddle points. The global minimum corresponding to a collinear Ar–BrCl configuration, which has been observed experimentally, is located at R = 4.10 Å and θ = 2.5° with a well depth of −285.207 cm{sup −1}. A nearly T-shaped structure and an anti-linear Ar–ClBr geometry is also predicted. The bound state calculations are preformed to study intermolecular vibrational modes, rotational levels and average structures for the complex. Our transition frequencies, spectroscopic constants and average structures for all isotopomers of the collinear isomer agree well with experimental data. We have also provided pure rotational transitional frequencies for both nearly T-shaped and anti-linear isomers. These results are significant for further experimental investigations of the Ar–BrCl dimer.

  8. Investigations on birefringence effects in polymer optical fiber Bragg gratings

    DEFF Research Database (Denmark)

    Hu, Xiaolian; Saez-Rodriguez, D.; Bang, Ole;


    because of the larger thermo-optic coefficient and smaller Young's modulus of polymer materials. (M)POFBGs are most often photowritten in poly(methylmethacrylate) (PMMA) materials using a continuous-wave 325 nm HeCd laser. For the first time to the best of our knowledge, we study photoinduced...... dependent loss (PDL) and differential group delay (DGD) were computed from the Jones matrix eigenanalysis using an optical vector analyser. Maximum values exceeding several dB and a few picoseconds were obtained for the PDL and DGD, respectively. The response to lateral force was finally investigated...

  9. Optical investigation of intra- and extra-cellular dynamics

    DEFF Research Database (Denmark)

    Leijnse, Natascha

    In this thesis we investigated intra- and extra-cellular dynamics with the help of optical tweezers and confocal imaging. Firstly, we measured in vivo diffusion inside endothelial cells by tracking lipid granules and compared the results to in vitro diffusion of polystyrene beads in wormlike...... micelles. Furthermore, we studied F-actin dynamics in, and curvature sensing of, a receptor and its ligand on artificially pulled membrane tethers. Force measurements between a cell and an approaching optically trapped bead were conducted in order to probe the endothelial cell's glycocalyx. Finally...

  10. An investigation into the electrochemical recovery of rare earth ions in a CsCl-based molten salt

    Energy Technology Data Exchange (ETDEWEB)

    Jiao, Shuqiang, E-mail: [School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing, 100083 (China); Zhu, Hongmin, E-mail: [School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing, 100083 (China)


    A CsCl-based melt, was used as a supporting electrolyte for a fuel cycle in pyrochemical separation, as it has a high solubility for lanthanide oxide. Cyclic voltammetry and square wave voltammetry were carried out to investigate the cathodic reduction of those rare earth ions. The results prove that the cathodic process of La(III) ions dissolved in a CsCl-based melt, with a one-step reduction La{sup 3+} + 3e{sup -} = La, and is similar to those of other reports which have utilised LiCl-KCl or CaCl{sub 2}-KCl molten salt systems. However, for the Ce(III) ions that dissolved in a CsCl-based melt, there is a significant difference when compared with published literature as there are two reduction steps instead of the reported single step Ce{sup 3+} + e{sup -} = Ce{sup 2+} and Ce{sup 2+} + 2e{sup -} = Ce. In order to explain the novel result, a detailed investigation was focused on the cathodic process of Ce(III) in a CsCl-based melt. The identification of the M-O (M = La, Ce) compounds that are stable in the electrolyte, as well as the determination of their solubility products, were carried out by potentiometric titration using an oxide ion sensor. Furthermore, the E-pO{sup 2-} (potential-oxide ion) diagram for the M-O stable compound was constructed by combining both theoretical and experimental data.

  11. Experimental and theoretical investigation of semiconductor optical amplifier (SOA) based all-optical switches

    DEFF Research Database (Denmark)

    Nielsen, Mads Lønstrup


    This thesis analyzes semiconductor optical amplifier (SOA) based all-optical switches experimentally and through numerical simulations. These devices are candidates for optical signal processing functionalities such as wavelength conversion, regeneration, and logic processing in future transparent...... optical networks. The factors governing the modulation bandwidth of SOAs are determined, and schemes for reducing detrimental patterning effects are discussed. Three types of SOA-based switches are investigated numerically: so-called standardmode and differential-mode switches, and the filtering assisted...... switch. Differential -mode switches are shown to eliminate one contribution to the patterning effects, referred to as the linear patterning. This enables operation at bitrates far beyond the limit set by the carrier lifetime, but ultimately a saturation-induced patterning effect, nonlinear patterning...

  12. Near-infrared spectroscopic investigation of water in supercritical CO2 and the effect of CaCl2

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zheming; Felmy, Andrew R.; Thompson, Christopher J.; Loring, John S.; Joly, Alan G.; Rosso, Kevin M.; Schaef, Herbert T.; Dixon, David A.


    Near-infrared (NIR) spectroscopy was applied to investigate the dissolution and chemical interaction of water dissolved into supercritical carbon dioxide (scCO2) and the influence of CaCl2 in the co-existing aqueous phase at fo empe e : 40 50 75 nd 100 C at 90 atm. Consistent with the trend of the vapor pressure of water, the solubility of pure water in scCO2 inc e ed f om 40 °C (0.32 mole%) o 100 °C (1.61 mole%). The presence of CaCl2 negatively affects the solubility of water in scCO2: at a given temperature and pressure the solubility of water decreased as the concentration of CaCl2 in the aqueous phase increased, following the trend of the activity of water. A 40 °C, the water concentration in scCO2 in contact with saturated CaCl2 aqueous solution was only 0.16 mole%, a drop of more than 50% as compared to pure water while that a 100 °C was 1.12 mole%, a drop of over 30% as compared to pure water, under otherwise the same conditions. Analysis of the spectral profiles suggested that water dissolved into scCO2 exists in the monomeric form under the evaluated temperature and pressure conditions, for both neat water and CaCl2 solutions. However, its rotational degrees of freedom decrease at lower temperatures due to higher fluid densities, leading to formation of weak H2O:CO2 Lewis acid-base complexes. Similarly, the nearly invariant spectral profiles of dissolved water in the presence and absence of saturated CaCl2 under the same experimental conditions was taken as evidence that CaCl2 dissolution in scCO2 was limited as the dissolved Ca2+/CaCl2 would likely be highly hydrated and would alter the overall spectra of waters in the scCO2 phase.

  13. Phosphane-stabilized gold clusters: investigation of the stability of [Au(13)(PMe (2)Ph) (10)Cl (2)] (3+). (United States)

    Li, Jia; Wang, Shu-Guang


    The phosphane-stabilized gold cluster [Au(13)(PMe(2)Ph)(10)Cl(2)](3+) was studied using density functional theory. The extraordinary stability of the cluster has been attributed to the stability of the gold core and the protection conferred by ligands. Here, five stability factors of the gold core were explained and verified by investigating the Au (13) (5+) core in detail. Interactions between the gold core and several PR(3) ligands (R = Me, H, I, Br, Cl, F) were investigated according to the different electron donor abilities of each ligand; bonding energy between the ligand and the gold core was found to increase with the electronegativity of the R substituent. Furthermore, two other aspects of the ligands were clarified: how the ligand stabilizes the Au (13) (5+) core, and which kind of ligand provides the best stabilization for the cluster.

  14. Electrochemical investigation on the redox chemistry of niobium in LiCl-KCl-KF-Na2O melts

    DEFF Research Database (Denmark)

    Gillesberg, Bo; Bjerrum, Niels; Barner, Jens H. Von


    The system LiCl-KCl-KF-1 mole percent K2NbF7 (molar ration F-/Nb = 8) has been investigated in-the temperature range 370 to 725 degrees C by cyclic and square wave voltammetry. In the temperature range from 370 to 520 degrees C Nb(V) was reduced to Nb(III) in two reversible steps: Nb(V) --> Nb(IV...


    Directory of Open Access Journals (Sweden)

    A. Kumar


    Full Text Available The single crystal growth  of tetrachloromercurate (II [HM-1] and tetrachlorozincate (II [HM-2] with 2-amino-5-chloropyridine has been performed by slow cooling (SC crystal growth technique of solution growth methodin which needle shaped transparent single crystals (0.5 x 0.2 x 0.2mm were obtained. The crystal structures of these hybrid materials have been studied by X-ray diffraction, experimental and computational methods. [HgCl4]2- anions have a distorted tetrahedral geometry and the tetrahedra hybrid structure exhibit interwoven inorganic-organic layers mingled through N-Hδ+...Clδ- hydrogen bonding interactions. The mercurophilic interactions [Hg...Hg = 3.984(5Å] and halogen interactions [Cl...Cl = 3.406(2Å] form 2D parallelogram pattern of secondary interactions in [HM-1] whereas for [HM-2] crystal structure is stabilized by Cl...Cl = 3.357(2Å interactions. UV-vis absorption spectra depict the change in optical band gap from 3.01 eV to 3.42 eV on replacing the metal halide group, could be due to increase in optical absorption as a function of wavelength. The Raman and Hyper-Raman tensors calculations were performed based on single crystal X-ray data and the Lagrangian strain tensor calculations show the degree of lattice distortion = 1.794 between [HM-1] and [HM-2] which are useful tools for the optical response properties of inorganic-organic hybrid derivatives. The photoluminescence emission spectra peaks were observed in the wavelength range of 371 to 598 nm for material [HM-1] and  in the wavelength range of 384 to 600 nm for material [HM-2] and lie in the visible range for both materials.

  16. ASE suppression of XeCl excimer laser MOPA system using UV electro-optical switch (United States)

    Hu, Yun; Zhao, Xue-qing; Xue, Quan-xi; Wang, Da-hui; Zheng, Guo-xin; Hua, Heng-qi; Zhang, Yongsheng; Zhu, Yong-xiang; Xiao, Wei-wei; Wang, Li


    In high power eximer laser system, amplified spontaneous emission (ASE) decreases the signal contrast ratio severely, leads to waveform broadening and distortion, and impacts on accurate physical experiments. In this article, based on principle of short pulse generation by electro-optical (E-O) switch, a method for ASE suppression of laser amplifiers chain was established. A series of studies on UV electro-optical switches were carried out, and electro-optical (E-O) switches with high extinction ratio were developed. In the waveform clipping experiments of the first pre-amplifier, the extinction ratio of the single and cascaded dual E-O switch reaches 103 and 104 order of magnitude, the laser pulse signal contrast ratio was promoted to 105 and 106 level, respectively. In the experiments of single channel MOPA (Master Oscillator Power Amplifier system), the cascaded dual E-O switch was adopted to suppress ASE of the whole system, and a fine narrow pulse was obtained on the target surface, which gives out one effective solution to the problem of waveform amplification of the high power eximer laser system.

  17. Optical and electrical conduction mechanisms of [N(CH3)3H]CdCl3 (United States)

    Kchaou, H.; Karoui, K.; Rhaiem, A. Ben


    The X-ray powder diffraction patterns shows that at room temperature [N(CH3)3H]CdCl3 crystallizes in the orthorhombic system with the Pbnm space group. The analysis of the data revealed the existence of optical allowed direct transition mechanisms with the band gap energy equal to 5.3 eV. The temperature dependences of the real part of dielectric permittivity show a relaxation process at high temperature that can be explained by the reorientational motion of alkyl chains. The alternative current (AC) electrical conduction in compound is governed by three processes, which can be attributed to several models: the correlated barrier hopping (CBH) model in phases I and II, the non-overlapping small polaron tunneling (NSPT) model in phases III and IV.

  18. Nuclear quadrupole interaction of 243Am3+ in LaCl3 measured via optical spectral-hole burning (United States)

    Liu, G. K.; Cao, Ruoxin; Beitz, James V.


    An optical spectral-hole burning technique has been used to study the nuclear quadrupole splitting in the ground state of 243Am3+ in LaCl3. The observed splitting is consistent with Am3+ ions on an axially symmetric site. The nuclear quadrupole coupling constant P=-75+/-1 MHz for the 7F0 ground state is obtained based on an effective operator Hamiltonian. The crystal-field antishielding effect dominates whereas contributions from the 5f electrons and from the pseudoquadrupole interaction are negligible (P5f/Platt=0.03). The Sternheimer antishielding factor, γ∞=-154, is determined and comparison is made between the actinide ion Am3+ and its rare-earth analogy Eu3+.

  19. Investigation of photoelectron action in cubic AgCl emulsion doped with formate ions

    Institute of Scientific and Technical Information of China (English)

    Yang Shao-Peng; Zhou Xian; Fu Guang-Sheng; Li Xiao-Wei; Tian Xiao-Dong; Han Li


    In recent years, the formate ion (HCO-2) as a kind of hole-to-electron converter has attracted much attention of photographic researchers. The formate ions can trap photo-generated holes, eliminate or reduce the electron loss caused by electron-hole recombination in latent image formation process. Through the hole-to-electron conversion, it can also release an extra electron or electron carrier, improving photosensitivity. In this paper the microwave absorption and dielectric spectrum detection technique is used to detect the time evolution behaviour of free photoelectrons generated by 35ps laser pulses in cubic AgCl emulsions doped with formate ions. The influence of different doping conditions of formate ions on the photoelectron decay kinetics of AgCl is analysed. It is found that when the HCO-2 content is 10-3mol/mol Ag and the doping position is 90% the electron decay time and lifetime reach their maxima due to the efficient trap of holes by formate ions.

  20. Structural, Electronic, and Optical Properties of BiOX1-xYx (X, Y = F, Cl, Br, and I) Solid Solutions from DFT Calculations. (United States)

    Zhao, Zong-Yan; Liu, Qing-Lu; Dai, Wen-Wu


    Six BiOX1-xYx (X, Y = F, Cl, Br, and I) solid solutions have been systematically investigated by density functional theory calculations. BiOCl1-xBrx, BiOBr1-xIx, and BiOCl1-xIx solid solutions have very small bowing parameters; as such, some of their properties increase almost linearly with increasing x. For BiOF1-xYx solid solutions, the bowing parameters are very large and it is extremely difficult to fit the related calculated data by a single equation. Consequently, BiOX1-xYx (X, Y = Cl, Br, and I) solid solutions are highly miscible, while BiOF1-xYx (Y = Cl, Br, and I) solid solutions are partially miscible. In other words, BiOF1-xYx solid solutions have miscibility gaps or high miscibility temperature, resulting in phase separation and F/Y inhomogeneity. Comparison and analysis of the calculated results and the related physical-chemical properties with different halogen compositions indicates that the parameters of BiOX1-xYx solid solutions are determined by the differences of the physical-chemical properties of the two halogen compositions. In this way, the large deviation of some BiOX1-xYx solid solutions from Vegard's law observed in experiments can be explained. Moreover, the composition ratio of BiOX1-xYx solid solutions can be measured or monitored using optical measurements.

  1. Investigations concerning the determination of NADH concentrations using optical biopsy (United States)

    Beuthan, Juergen; Bocher, Thomas; Minet, Olaf; Roggan, Andre; Schmitt, Isabella; Weber, A.; Mueller, Gerhard J.


    The intrinsic NADH autofluorescence intensity of biological tissue depends on the local, cellular concentration of this coenzyme. It plays a dominant role in the Krebs-Cycle and therefore serves as indicator for the vitality of the observed cells. Due to individually and locally varying boundary conditions and optical tissue properties, which are scattering coefficients, absorption coefficients and g-factors the fluorescence signal needs to be rescaled. One possible rescaling method is the theoretical derived Photon Migration Theory. Our new rescaling method is partly based on measurements and partly theoretical derived. By using the 4 information channels: LIF time-resolved signal, biochemical concentration measurements, Monte Carlo simulations with optical parameters and microscopic investigations we demonstrate that simultaneous detection of the fluorescence and the backscattering signal can easily and accurately provide rescaled, quantitative values for the NADH concentrations.

  2. Experimental and theoretical investigation of electro-optic and all-optical implementations of wavelength converting 2R-regenerators

    DEFF Research Database (Denmark)

    Wolfson, David; Mikkelsen, Benny; Danielsen, Søren Lykke


    We investigate and compare the regenerative capability of electro-optic wavelength converters based on electrically controlled external Mach-Zehnder (MZ) modulators and all-optical wavelength converters based on all-optically controlled external MZ modulators. The latter incorporates semiconductor...... optical amplifiers (SOAs) as optically controlled phase shifters. Experiments demonstrate a 5-6 dB noise suppression capability for both the electro-optic and the all-optical implementation of the wavelength-converting regenerators. The performance can be further improved by cascading two converters...

  3. Investigation of OpenCL support in the VecGeom geometry package

    CERN Document Server

    Biro, Gabor


    High energy physics always needed a significant amount of computational resources, and with the upgrades of the experiments this need is still growing. Though the computational capacity of the hardwares are increasing as well, since the increasing of the clock frequency of the CPUs stopped a few years ago it needs more effort from the sofware side to exploit all the capabilities. The goal of the VecGeom package is to offer a geometry package that can take advantage most of the modern computing technologies. This report describes the benefits and handicaps of the implementation of the OpenCL support in {VecGeom}, bearing in mind that it has to be as generic as possible and it has to fit in the already existing generic templated structure.

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

    Directory of Open Access Journals (Sweden)

    Little Douglas J.


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

  5. Investigating the transverse optical structure of spider silk micro-fibers using quantitative optical microscopy (United States)

    Little, Douglas J.; Kane, Deb M.


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

  6. Optical and THz reflectance investigations of organic solar cells (United States)

    Sporea, Dan; Mihai, Laura; Sporea, Adelina; Galagan, Yulia


    Two Organic Photovoltaic devices having a photoactive layer containing Poly[N-9'-heptadecanyl-2,7-carbazole-alt-5,5- (4',7'-di-2-thienyl-2',1',3'-benzothiadiazole)] (PCDTBT) and [6,6]-phenyl C61-butyric acid methyl ester (PCBM, 99%), and the layer sequences - glass/ITO/ZnO/PAL/PEDOT:PSS/Ag/encapsulation were non-destructively investigated by diffuse optical spectral reflectance, THz spectroscopy and THz imaging. The proposed methods proved to be powerful tools to support quality assurance in organic solar cells development, facilitating both the localization of manufacturing defects and the device degradation, as they are combined with "classical" evaluation means.

  7. Investigation of the Solidification Behavior of NH4Cl Aqueous Solution Based on a Volume-Averaged Method (United States)

    Li, Ri; Zhou, Liming; Wang, Jian; Li, Yan


    Based on solidification theory and a volume-averaged multiphase solidification model, the solidification process of NH4Cl-70 pct H2O was numerically simulated and experimentally verified. Although researchers have investigated the solidification process of NH4Cl-70 pct H2O, most existing studies have been focused on analysis of a single phenomenon, such as the formation of channel segregation, convection types, and the formation of grains. Based on prior studies, by combining numerical simulation and experimental investigation, all phenomena of the entire computational domain of the solidification process of an NH4Cl aqueous solution were comprehensively investigated for the first time in this study. In particular, the sedimentation of equiaxed grains in the ingot and the induced convection were reproduced. In addition, the formation mechanism of segregation was studied in depth. The calculation demonstrated that the equiaxed grains settled from the wall of the mold and gradually aggregated at the bottom of the mold; when the volume fraction reached a critical value, the columnar grains stopped growing, thus completing the columnar-to-equiaxed transition (CET). Because of solute partitioning, negative segregation occurred at the bottom region of the ingot concentrated with grains, whereas a wide range of positive segregation occurred in the unsolidified, upper part of the ingot. Experimental investigation indicated that the predicted results of the sedimentation of the equiaxed grains in the ingot and the convection types agreed well with the experimental results, thus revealing that the sedimentation of solid phase and convection in the solidification process are the key factors responsible for macrosegregation.

  8. Investigation on stability of directionally solidified CBr4-C2Cl6 lamellar eutectic by using multiphase field simulation

    Institute of Scientific and Technical Information of China (English)

    Zhu Yao-chan; Wang Jin-Cheng; Yang Gen-Cang; Zhao Da-Wen


    With the multiphase field method,the stability of lamellar basic state is investigated during the directional solidification of eutectic alloy CBr4-C2Cl6.A great number of lamellar patterns observed in experiments are simulated,and a stability diagram for lamellar pattern selections is presented.The simulated growth behaviours of these patterns are found to be qualitatively consistent with Karma et al'S numerical calculations and experimental results.The formation of the primary instability is attributed to the destabilization of solute boundary layer.

  9. Optical investigations on the wide bandgap semiconductors diamond and aluminum nitride

    Energy Technology Data Exchange (ETDEWEB)

    Teofilov, Nikolai


    In the context of this thesis, new results about optical defects and intrinsic properties of diamond, AlN and AlGaN alloys have been obtained. The main experimental techniques used were low temperature cathodoluminescence and photoluminescence spectroscopy. First, different aspects of intentional and background doping of diamond were discussed. Thus, the most commonly observed green luminescence emission from boron doped HPHT diamonds has been studied by means of temperature dependent CL in a wide temperature range from 10 K to 450 K. One further subject, addressing deep defect nitrogen related luminescence was a study of nitrogen addition in combustion flame grown CVD diamond layers. Two further topics concern intrinsic excitations in diamond, free excitons and electron-hole drops. Several important parameters like the critical density, the critical temperature, and the low-temperature density inside the drops were evaluated. The ground state density of the electron-hole condensate in diamond is about {approx} 42 times larger than that in Si, and the critical temperature takes very high values in the range of 165K.. 173K. Cathodoluminescence investigations on epitaxial wurtzite AlN layers grown on sapphire, SiC, and Si substrates, have shown that although the material is generally of good optical quality, deep level luminescence are still dominating the spectra. Relatively sharp near-band-edge transitions have been observed in all three samples that exhibit significantly reduced line widths for the AlN/sapphire and the AlN/SiC samples. Much broader emission lines in the near band-gap region have been observed for the first time from the AlN sample grown on Si (111) substrate. Temperature dependent CL measurements and numerical line decompositions reveal complicated substructures in the excitonic lines. The temperature dependence of the energy positions and broadening parameters of the transition have been studied and compared with the other materials. Epitaxial Al

  10. Multi-Wavelength Optical Pyrometry Investigation for Turbine Engine Applications. (United States)

    Estevadeordal, Jordi; Nirmalan, Nirm; Wang, Guanghua; Thermal Systems Team


    An investigation of optical Pyrometry using multiple wavelengths and its application to turbine engine is presented. Current turbine engine Pyrometers are typically broadband Si-detector line-of-sight (LOS) systems. They identify hot spots and spall areas in blades and bucket passages by detection of bursts of higher voltage signals. However, the single color signal can be misleading for estimating temperature and emissivity variations in these bursts. Results of the radiant temperature, multi-color temperature and apparent emissivity are presented for turbine engine applications. For example, the results indicate that spall regions can be characterized using multi-wavelength techniques by showing that the temperature typically drops and the emissivity increases and that differentiates from the emissivity of the normal regions. Burst signals are analyzed with multicolor algorithms and changes in the LOS hot-gas-path properties and in the suction side, trailing edge, pressure side, fillet and platform surfaces characterized.

  11. LDA+DMFT investigation of the organic charge transfer salt κ-(BEDT-TTF)2Cu[N(CN)2]Cl (United States)

    Feldner, Helene; Jacko, Anthony; Rose, Eva; Dressel, Martin; Valenti, Roser; Jeschke, Harald O.


    We combine density functional theory with dynamical mean field theory for the study of organic molecular crystals using a new scheme to construct molecular Wannier functions. We calculate spectral and optical properties for the strongly correlated material κ-(BEDT-TTF)2Cu[N(CN)2]Cl. The new method allows us to analyze the contributions of intradimer and interdimer contributions to the optical conductivity on the same footing. We find in agreement with experiment that strong correlations lead to a Hubbard peak in the optical conductivity.

  12. Pressure dependence of the metal-insulator transition in κ-(BEDT-TTF)2Hg(SCN)2Cl: optical and transport studies (United States)

    Löhle, A.; Rose, E.; Singh, S.; Beyer, R.; Tafra, E.; Ivek, T.; Zhilyaeva, E. I.; Lyubovskaya, R. N.; Dressel, M.


    The two-dimensional organic conductor κ-(BEDT-TTF)2-Hg(SCN)2Cl exhibits a pronounced metal-insulator transition at {{T}\\text{CO}}=30 K. From the splitting of the molecular vibrations, the phase transition can be unambiguously assigned to charge-ordering with 2{δρ}=0.2e . We have investigated the pressure evolution of this behavior by temperature-dependent electrical transport measurements and optical investigations applying hydrostatic pressure up to 12 kbar. The data reveal a mean-field like down-shift of {{T}\\text{CO}}≤ft( p\\right) with a critical pressure of {{p}c}=0.7+/- 0.1 kbar and a metallic state above the suppression of the charge-ordered state; no traces of superconductivity could be identified down to T  =  1.5 K. As the charge order {δρ} sets in abruptly with decreasing temperature, its size remains unaffected by pressure. However, the fraction of charge imbalanced molecules decreases until it is completely absent above 1.6 kbar.

  13. Electronic structure and optical properties of Cs2HgCl4: DFT calculations and X-ray photoelectron spectroscopy measurements (United States)

    Lavrentyev, A. A.; Gabrelian, B. V.; Vu, V. T.; Parasyuk, O. V.; Fedorchuk, A. O.; Khyzhun, O. Y.


    A high-quality single crystal of cesium mercury tetrabromide, Cs2HgCl4, was synthesized by using the vertical Bridgman-Stockbarger method and its electronic structure was studied from both experimental and theoretical viewpoints. In particular, X-ray photoelectron spectra were measured for both pristine and Ar+ ion-bombarded Cs2HgCl4 single crystal surfaces. The present XPS measurements indicate that the Cs2HgCl4 single crystal surface is sensitive with respect to Ar+ ion-bombardment: such a treatment changes substantially its elemental stoichiometry. With the aim of exploring total and partial densities of states within the valence band and conduction band regions of the Cs2HgCl4 compound, band-structure calculations based on density functional theory (DFT) using the augmented plane wave + local orbitals (APW + lo) method as incorporated within the WIEN2k package are performed. The calculations indicate that the Cl 3p states are the principal contributors in the upper portion of the valence band, while the Hg 5d and Cs 5p states dominate in its lower portion. In addition, the calculations allow for concluding that the unoccupied Cl p and Hg s states are the main contributors to the bottom of the conduction band. Furthermore, main optical characteristics of Cs2HgCl4, namely dispersion of the absorption coefficient, real and imaginary parts of dielectric function, electron energy-loss spectrum, refractive index, extinction coefficient and optical reflectivity, are elucidated based on the DFT calculations.

  14. Optical limiting of niobic tellurite glass induced by self-trapped exciton absorption of the AgCl nanocrystal dopant

    Institute of Scientific and Technical Information of China (English)

    ZHAO ZhenYu; LIN Jian; JIA TianQin; SUN ZhenRong; WANG ZuGeng


    Nioblc tellurite glass doped by silver chloride nanocrystal was prepared with the melting-quenching and heat treatment method, and the self-trapped exciton absorption band of the silver chloride nanocrystal was observed at 532 nm in the UV-visible absorption spectrum. The glass structure chara-cteristics were investigated by Raman spectroscopy, and the mechanism of self-trapped exciton was analyzed by Jahn-Teller model. Its optical limiting was measured with 532 nm picosecond laser pulses, and the corresponding nonlinear absorption coefficient was measured with open-aperture Z-scan. The experimental results showed that optical limiting at 532 nm was attributed to free carrier absorption between the self-trapped state and the continuum band.

  15. Investigation of a $^{85}$Rb Dark Magneto-Optical Trap using an Optical Nanofibre

    CERN Document Server

    Russell, L; Tiwari, V B; Chormaic, S Nic


    We report here measurements on a dark magneto-optical trap (DMOT) of 85Rb atoms using an optical nanofibre (ONF) with a waist of ∼~1 μm. The DMOT is created using a doughnut-shaped repump beam along with a depump beam for efficient transfer of cold atoms from the bright hyperfine ground state (F=3) into the dark hyperfine ground state (F=2). The fluorescence from the cold 85Rb atoms of the DMOT is detected by coupling it into the fibre-guided modes of the ONF. The measured fractional population of cold atoms in the bright hyperfine ground state (p) is as low as ∼0.04. The dependence of loading rate of DMOT on cooling laser intensity is investigated and also compared with the loading rate of a bright-MOT (BMOT). This work lays the foundation for the use of an ONF for probing of a small number of atoms in an optically-dense cold atomic cloud.

  16. Preliminary Investigation of an Integrated Optic Sampler for HF Signals (United States)


    fibre optic links). The response is reasonably flat out to -3 GHz, dropping to -3 dBc at -4.8 GHz. The S1 1 reflection coefficient rapidly approaches 0...sampling rate can probably be extended to -8 GHz by using a 1 GHz SRD to gain-switch the laser, followed by a fibre optic multiplexing system to split...and the possibility of causing optical instability. This problem is easily avoided by inserting an optical isolator into the fibre optic line. 5

  17. Investigation of Stable C and Cl Isotope Effects of Trichloroethene and Tetrachloroethylene during Evaporation at Different Temperatures

    Institute of Scientific and Technical Information of China (English)

    Tingting Yu; Yiqun Gan; Aiguo Zhou; Kai Yu; Yunde Liu


    There are variations of reported isotope enrichment factors of chlorinated organic contaminants in evaporation processes. Trichloroethene (TCE) and tetrachloroethylene (PCE) were chosen to study carbon and chlorine isotope effects during evaporation at different temperatures. Equilibrium vapor-liquid carbon and chlorine isotope effects experiments were also conducted. In the equilibrium liquid-vapor system, the 13C was enriched but 37Cl was depleted in the vapor phase, being consistent with previous results. For evaporation average carbon isotope enrichment factor εC were +0.28‰± 0.01‰ for TCE and +0.56‰±0.09‰ for PCE at temperature from 20 to 26 ºC. Meanwhile, average chlorine isotope enrichment factor εCl were -1.33‰±0.21‰ for TCE and -1.00‰±0.00‰ for PCE. The results indicate that during evaporation the equilibrium isotope effect attenuates the magnitude of carbon isotope fractionation whereas enhances the chlorine isotope effect. Isotope fractionation during evaporation is determined by both equilibrium and kinetic factors. Chlorine isotope fractionation is influenced by the evaporation rate which is linked to temperature. When using stable isotope to investigate the behavior of chlorinated organic contaminants in groundwater with slow biodegradation rate, the isotope fractionation resulted from evaporation should be taken into consideration. Furthermore, the environment conditions such as temperature are also factors to be considered.

  18. Investigation of sodalites for conditioning halide salts (NaCl and NaI): Comparison of two synthesis routes

    Energy Technology Data Exchange (ETDEWEB)

    Bardez, Isabelle; Campayo, Lionel; Rigaud, Danielle; Chartier, Myriam; Calvet, Aurelie [CEA, Laboratoire d' Etudes des Materiaux Ceramiques pour le Conditionnement, Site de Marcoule, Batiment 208, B.P. 17171, 30207 Bagnols sur Ceze cedex (France)


    Sodalites with the general formula Na{sub 8}Al{sub 6}Si{sub 6}O{sub 24}X{sub 2} (where X = Cl or I) were investigated for ceramic conditioning of halide salts (NaCl and NaI). Because of the tendency of halides to volatilize at high temperature, two synthesis routes were tested to optimize the halide content in the sodalite phase. The first is based on heating at high temperature of a [nepheline NaAlSiO{sub 4} + salt] mixture prepared by a dry process. The second, performed at low temperature, consists of the reaction in aqueous media between kaolinite (Al{sub 2}Si{sub 2}O{sub 5}(OH){sub 4}), sodium hydroxide (NaOH) and the salt. The present study compares these two syntheses and examines differences between chloro-sodalite and iodo-sodalite based on X-ray diffraction and infrared spectroscopy. The next step will consist in sintering the resulting powder samples to obtain dense ceramics. (authors)

  19. Synthesis, crystal and electronic structure, and optical property of the pentanary chalcohalide Ba{sub 3}KSb{sub 4}S{sub 9}Cl

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Hua-Jun, E-mail: [Laboratory of Applied Research on the Characteristic Resources in the North of Guizhou Province, School of Chemistry and Chemical Engineering, Zunyi Normal College, Zunyi, Guizhou 563002 (China); State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China); Liu, Peng-Fei [State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China); University of Chinese Academy of Sciences, Beijing 100039 (China)


    The pentanary chalcohalide Ba{sub 3}KSb{sub 4}S{sub 9}Cl has been prepared from stoichiometric mixtures of KCl, Ba, Sb, and S in an evacuated silica tube, which is the first example of chalcohalides in the pentanary A/Ae/Sb/Q/X (A=alkali metal; Ae=alkaline-earth metal; Q=S, Se, Te; X=F, Cl, Br, I) system. This material crystallize in the Pnnm space group and its new structure type comprises one-dimensional (1D) [Sb{sub 3}S{sub 7}]{sup 5−} chains running down the [001] direction separated by isolated dimeric Sb{sub 2}S{sub 4} polyhedra, Ba{sup 2+}, K{sup +}, and Cl{sup −}, respectively. The optical gap of 1.99 eV for Ba{sub 3}KSb{sub 4}S{sub 9}Cl was deduced from the UV/vis reflectance spectroscopy and DFT study indicates a indirect band gap with an electronic transfer excitation of S 3p to Sb 5p orbital electrons. - Graphical abstract: The pentanary chalcohalide Ba{sub 3}KSb{sub 4}S{sub 9}Cl has been prepared, which contains one-dimensional (1D) [Sb{sub 3}S{sub 7}]{sup 5−} chains running down the [001] direction separated by isolated dimeric Sb{sub 2}S{sub 4} polyhedra, Ba{sup 2+}, K{sup +}, and Cl{sup −}, respectively. - Highlights: • Ba{sub 3}KSb{sub 4}S{sub 9}Cl is the first example of chalcohalides in the pentanary A/Ae/Sb/Q/X (A=alkali metal; Ae= alkaline-earth metal; Q=S, Se, Te; X=F, Cl, Br, I) system. • This material crystallizes in a new structure type with one-dimensional (1D) [Sb{sub 3}S{sub 7}]{sup 5−} chains running down the [001] direction separated by isolated dimeric Sb{sub 2}S{sub 4} polyhedra, Ba{sup 2+}, K{sup +}, and Cl{sup −}, respectively. • The optical gap of 1.99 eV for Ba{sub 3}KSb{sub 4}S{sub 9}Cl was deduced from UV/Vis reflectance spectroscopy.

  20. Investigation of electrochemical etch differences in AlGaAs heterostructures using Cl{sub 2} ion beam assisted etching

    Energy Technology Data Exchange (ETDEWEB)

    Anglin, Kevin, E-mail:; Goodhue, William D. [Massachusetts Institute of Technology Lincoln Laboratory, 244 Wood St., Lexington, Massachusetts 02420 and Department of Physics and Applied Physics, University of Massachusetts Lowell, 1 University Ave., Lowell, Massachusetts 01854 (United States); Swint, Reuel B.; Porter, Jeanne [Massachusetts Institute of Technology Lincoln Laboratory, 244 Wood St., Lexington, Massachusetts 02420 (United States)


    A deeply etched, anisotropic 45° and 90° mirror technology is developed for Al{sub x}Ga{sub 1−x}As heterostructures using a Cl{sub 2} ion beam assisted etching system. When etching vertically, using a conductive low-erosion Ni mask, electrochemical etch differences between layers with various Al mole fractions caused nonuniform sidewall profiles not seen in semi-insulating GaAs test samples. These variations, based on alloy composition, were found to be negligible when etching at a 45°. A Si{sub 3}N{sub 4}-Ni etch mask is designed in order to electrically isolate charge buildup caused by the incoming Ar{sup +} ion beam to the Ni layer, preventing conduction to the underlying epitaxial layers. This modification produced smoothly etched facets, up to 8 μm in depth, enabling fabrication of substrate–surface-emitting slab-coupled optical waveguide lasers and other optoelectronic devices.

  1. Spatial Fourier-decomposition optical fluorescen tomography-theoretical investigation

    Institute of Scientific and Technical Information of China (English)

    Cheng Liu; Dug Young Kim; Jianqiang Zhu


    A new three-dimensional (3D) optical fluorescent tomographic imaging scheme is proposed with structured illumination and spatial Fourierdomain decomposition methods for the first time. In this spatial Fourier-decomposition optical fluorescence tomography (SF-OFT), the intensity of focused excitation light from an objective lens is modulated to be a cosine function along the optical axis of the system. For a given position in a two-dimensional (2D) raster scanning process, the spatial frequency of the cosine function along the optical axis sweeps in a proper range while a series of fluorescence intensity are detected accordingly. By making an inverse discrete cosine transformation of these recorded intensity profiles, the distribution of fluorescent markers along the optical axis of a focused laser beam is obtained. A 3D optical fluorescent tomography can be achieved with this proposed SF-OFT technique with a simple 2D raster scanning process.

  2. Magnetic, resonance, and optical properties of Cu3Sm (SeO3)2O2Cl : A rare-earth francisite compound (United States)

    Zakharov, K. V.; Zvereva, E. A.; Markina, M. M.; Stratan, M. I.; Kuznetsova, E. S.; Dunaev, S. F.; Berdonosov, P. S.; Dolgikh, V. A.; Olenev, A. V.; Klimin, S. A.; Mazaev, L. S.; Kashchenko, M. A.; Ahmed, Md. A.; Banerjee, A.; Bandyopadhyay, S.; Iqbal, A.; Rahaman, B.; Saha-Dasgupta, T.; Vasiliev, A. N.


    In this combined experimental and theoretical paper, we study the properties of Cu3Sm (SeO3)2O2Cl belonging to the francisite family of compounds, which are novel frustrated layered compounds. Cu3Sm (SeO3)2O2Cl is synthesized through a solid state reaction. Characterizations through measurements of magnetization, specific heat, X-band electron spin resonance, and rare-earth optical spectroscopy, establish that the compound orders antiferromagnetically at TN=35 K and undergoes a spin-reorientation phase transition at TC=8.5 K due to the interplay of anisotropies in transition metal and rare-earth subsystems. The ground state Kramers doublet of Sm is found to split only at T kagome-type magnetic subsystem of Cu3Sm (SeO3)2O2Cl .

  3. Effect on the morphology and optical properties of CH3NH3PbI3 with additive of NH4Cl (United States)

    Yan, Xiaoliang; Yang, Xiao; Wang, Ruizhi; Li, Heng; Sheng, Chuanxiang


    Rapid emergence of solar cells based on mixed organic-inorganic halide perovskite have led to high power conversion efficiencies of over 20% in recent years. Looking for a simple and convenient way to fine-control of the perovskite film morphology is becoming one of the main issues. In this work, we explore the effect of adding NH4Cl on crystallization process and optical properties of perovskite. With adding NH4Cl, the perovskite films prepared by one-step method present better morphology than films without adding NH4Cl, namely, smoother surface and better coverage which result in uniform and much more stable photoluminescence intensities as well as longer lifetime of photoexcitations. More importantly, the photovoltaic cells fabricated with the addition of the NH4Cl have far better performance than the cells without additives. Therefore, one-step fabrication method can also control the morphology of perovskite films finely for both optical application and solar cells with adding proper additive.

  4. Investigation of optical limiting in C60 solution (United States)

    Joshi, M. P.; Mishra, S. R.; Rawat, H. S.; Mehendale, S. C.; Rustagi, K. C.


    Experimental and theoretical studies of optical limiting for 30 ns pulses at 527 nm in C60 are reported. The results indicate that the optical limiting action may involve contribution from other nonlinear loss mechanisms in addition to increased absorption from the photoexcited triplet state.

  5. Nonlinear optical switching and optical limiting in colloidal CdSe quantum dots investigated by nanosecond Z-scan measurement (United States)

    Valligatla, Sreeramulu; Haldar, Krishna Kanta; Patra, Amitava; Desai, Narayana Rao


    The semiconductor nanocrystals are found to be promising class of third order nonlinear optical materials because of quantum confinement effects. Here, we highlight the nonlinear optical switching and optical limiting of cadmium selenide (CdSe) quantum dots (QDs) using nanosecond Z-scan measurement. The intensity dependent nonlinear absorption and nonlinear refraction of CdSe QDs were investigated by applying the Z-scan technique with 532 nm, nanosecond laser pulses. At lower intensities, the nonlinear process is dominated by saturable absorption (SA) and it is changed to reverse saturable absorption (RSA) at higher intensities. The SA behaviour is attributed to the ground state bleaching and the RSA is ascribed to free carrier absorption (FCA) of CdSe QDs. The nonlinear optical switching behaviour and reverse saturable absorption makes CdSe QDs are good candidate for all-optical device and optical limiting applications.

  6. Late Quaternary Glacial Chronology in the Cordillera de Talamanca, Costa Rica, Investigated Using Cosmogenic Cl-36 Surface Exposure Dating (United States)

    Li, Y.; Potter, R.; Horn, S.; Orvis, K. H.


    The role of the tropics in past and future climate change has garnered significant attention in recent decades, but debate still exists over climate linkages between the tropics and the middle and high latitudes. Glaciers in tropical mountains are highly sensitive indicators of climate, and glacial landforms left behind by past glacier fluctuations provide key evidence of paleoclimate trends and their forcing mechanisms. We investigated late Quaternary glacial chronology from two glaciated valleys on the Chirripó massif in the Cordillera de Talamanca, Costa Rica. Previous studies in this highland have constrained the most recent deglaciation to 12.4-9.7 ka cal BP based on radiocarbon dates on basal sediments of glacial lakes within the cirque at the head of the Morrenas Valley. However, no studies have been conducted to constrain the ages of the moraines located down valley. We dated the formation ages of these moraines in the Morrenas and Talari valleys using cosmogenic Cl-36 surface exposure dating. Our results indicate a major glacial event ~21-18 ka, broadly synchronous with the global Last Glacial Maximum (LGM). Glaciers during this period advanced 3.2-3.4 km down valley on both sides of the Chirripó massif. Our ages also suggest periods of glacial retreat or standstills ~18-10 ka before complete deglaciation of this highland ~10 ka. These results provide insight into the timing and extent of glacial events in this tropical highland that is of critical importance for reconstructing regional and global climate patterns.

  7. Fiber-Optic Network Architectures for Onboard Avionics Applications Investigated (United States)

    Nguyen, Hung D.; Ngo, Duc H.


    This project is part of a study within the Advanced Air Transportation Technologies program undertaken at the NASA Glenn Research Center. The main focus of the program is the improvement of air transportation, with particular emphasis on air transportation safety. Current and future advances in digital data communications between an aircraft and the outside world will require high-bandwidth onboard communication networks. Radiofrequency (RF) systems, with their interconnection network based on coaxial cables and waveguides, increase the complexity of communication systems onboard modern civil and military aircraft with respect to weight, power consumption, and safety. In addition, safety and reliability concerns from electromagnetic interference between the RF components embedded in these communication systems exist. A simple, reliable, and lightweight network that is free from the effects of electromagnetic interference and capable of supporting the broadband communications needs of future onboard digital avionics systems cannot be easily implemented using existing coaxial cable-based systems. Fiber-optical communication systems can meet all these challenges of modern avionics applications in an efficient, cost-effective manner. The objective of this project is to present a number of optical network architectures for onboard RF signal distribution. Because of the emergence of a number of digital avionics devices requiring high-bandwidth connectivity, fiber-optic RF networks onboard modern aircraft will play a vital role in ensuring a low-noise, highly reliable RF communication system. Two approaches are being used for network architectures for aircraft onboard fiber-optic distribution systems: a hybrid RF-optical network and an all-optical wavelength division multiplexing (WDM) network.

  8. Investigations of Abrupt Movements of Optically Trapped Water Droplets (United States)

    Murphy, Shawntel; McCann, Lowell I.


    We have used a single beam optical trap (optical tweezers) to capture individual water droplets in air. A 3-dimensional viewing system consisting of a two axis microscope allows the trapped droplet to be viewed from the top and the side simultaneously. The position of the droplet is determined with a digital camera at a rate up to 700Hz. We have observed abrupt movements along the beam in two situations: As a pure water droplet evaporates, the movements occur at specific size intervals as the diameter decreases. For non-evaporating saltwater droplets the movements rapidly occur for certain ranges of beam power, and not at all for other ranges of power.

  9. Crystallographic Investigations into Properties of Acentric Hybrid Perovskite Single Crystals NH(CH3)3SnX3(X = Cl, Br)

    KAUST Repository

    Dang, Yangyang


    The hybrid perovskites with special optoelectronic properties have attracted more attention to the scientific and industrial applications. However, because of the toxicity and instability of lead complexes, there is interest in finding a nontoxic substitute for the lead in the halides perovskites and solving the ambiguous crystal structures and phase transition of NH(CH3)3SnX3 (X = Cl, Br). Here, we report the bulk crystal growths and different crystal morphologies of orthorhombic hybrid perovskites NH(CH3)3SnX3 (X = Cl, Br) in an ambient atmosphere by bottom-seeded solution growth (BSSG) method. More importantly, detailed structural determination and refinements, phase transition, band gap, band structure calculations, nonlinear optical (NLO) properties, XPS, thermal properties, and stability of NH(CH3)3SnX3 (X = Cl, Br) single crystals are demonstrated. NH(CH3)3SnCl3 single crystal undergoes reversible structural transformation from orthorhombic space group Cmc21 (no. 36) to monoclinic space group Cc (no. 9) and NH(CH3)3SnBr3 belongs to the orthorhombic space group Pna21 (no. 33) by DSC, single-crystal X-ray diffraction and temperature-dependent SHG measurements, which clarify the former results. These results should pave the way for further studies of these materials in optoelectronics.

  10. Theoretical and experimental investigation of optically spin-injected VECSEL (United States)

    Joly, Alexandre; Frougier, Julien; Baili, Ghaya; Alouini, Mehdi; George, Jean-Marie; Sagnes, Isabelle; Dolfi, Daniel


    We report theoretical and experimental analysis of spin-injected VECSELs. First, we fabricate and characterize an optically pumped (100)-oriented InGaAs/GaAsP multiple quantum well VECSEL. The structure is designed to allow the integration of a Metal-Tunnel-Junction ferromagnetic spin-injector for future electrical injection. We report here the control at room temperature of the VECSEL polarization using optical spin injection in the active medium. The switching between two highly circular polarization states had been demonstrated using an M-shaped extended cavity in multi-modes lasing. This first result witnesses an efficient spin-injection in the active medium of the laser. Then, we report birefringence measurements of the VECSEL in oscillating conditions. The proposed technique relies on the measurement in the microwave domain of the beatnote between the oscillating mode and the amplified spontaneous emission of the cross-polarized non-lasing field lying in the following longitudinal mode. This technique is shown to offer extremely high sensitivity and accuracy enabling to track the amount of residual birefringence according to the laser operation conditions. Finally, we discuss the compensation of the residual linear phase anisotropy by controlling the birefringence of an intracavity electro-optical crystal. A 44-fold birefringence reduction is obtained. Besides, we study the modification of the laser polarization eigen states with birefringence compensation: a rotation of the linear polarization state is observed when the total phase anisotropy is reduced. An elliptical polarization eigen state is obtained at the minimum of the birefringence into the laser cavity, more favorable for spin injection.

  11. Investigation of Optically Induced Avalanching in GaAs (United States)


    by Bovino , et al 4 to increase the hold off voltage. The button switch design of Fig. 4c has been used by several researchers5 ’ 7 to obtain the...ul Long flashover palh Figure 3b. 434 Optical Jlatlern a. Mourou Switch b. Bovino Switch c. Button Switch Figure 4. Photoconductive Switches...Technology and Devices Laboratory, ERADCOM (by L. Bovino , et. all) 4 • The deposition recipe for the contacts is 1) 50 ANi (provides contact to GaAs

  12. The optical method for investigation of the peritonitis progressing process (United States)

    Guminetskiy, S. H.; Ushenko, O. G.; Polyanskiy, I. P.; Motrych, A. V.; Grynchuk, F. V.


    There have been given the results of the spectrophotometric examination of the dogs' and rats' venous and whole blood plasma taken in the process of the peritonitis progressing within the spectral interval λ = 220 - 320 nm (for plasma) and λ = 350 - 610 nm (for the whole blood). It has been defined that D-optical density values in the field of the long-waved maximum of plasma absorption intensity of the venous blood at λ = 280 nm depend upon the intensity of the inflammatory process and also upon the circumstances against the background of which it started to progress. It was found out that the dynamics of D= values changes for λ = 540 (or 570) nm in the process of the peritonitis progressing in case of the whole blood taken from a portal vein is a mirror symmetrical if to compare to the same dynamics for the blood from cava inferior. The defined conformities with regularities may have a diagnostic meaning. It was also found out that the biggest influence upon the dynamics of D-values at λ = 280nm of the venous blood plasma has the content of the circulating immune complexes, necrosis factor of α-tumors and interleukin - 2, the changes of which explain for almost on 100% the distribution of the optical density parameters and what proves a possible immunologic explanation of its changes.

  13. Investigating phthalate and 1,3-diether coverage and dynamics on the (104) and (110) surfaces of MgCl2-supported Ziegler-Natta catalysts

    KAUST Repository

    Credendino, Raffaele


    In this work we present a systematic DFT analysis of the effect of surface coverage on the coordination properties of two industrial Lewis bases, dimethyl phthalate and 9,9-bis(methoxymethyl)fluorene, to the (104) and (110) surfaces of MgCl2. Further, we investigated several possible migration pathways for the migration of the Lewis bases on the same MgCl2 monolayer. Our study clearly shows that complete coverage of the Mg vacancies on the surface by coordinating dimethyl phthalate or 9,9-bis(methoxymethyl)fluorene is hampered by steric repulsion between vicinally coordinated donor molecules. Further, our study clearly indicates that both dimethyl phthalate and 9,9-bis(methoxymethyl) fluorene migration on the same MgCl2 monolayer on the (104) and (110) surfaces basically requires donor dissociation. © 2014 American Chemical Society.

  14. Investigating alkoxysilane coverage and dynamics on the (104) and (110) surfaces of MgCl 2-supported Ziegler-Natta catalysts

    KAUST Repository

    Credendino, Raffaele


    In this work, we present a systematic DFT analysis of the effect of surface coverage on the coordination properties of alkoxysilanes to the (104) and (110) surfaces of MgCl 2. Furthermore, we investigated several possible migration pathways for alkoxysilane migration on the same surfaces. Our study clearly shows that complete coverage of the Mg vacancies on the surface by coordinating alkoxysilanes is hampered by steric repulsion between vicinally coordinated donor molecules. Our study clearly indicates that alkoxysilane migration between different MgCl 2 monolayers on the (104) and (110) surfaces requires donor dissociation. The same holds for alkoxysilane migration on a single (110) MgCl 2 monolayer. However, in the case of the (104) surface we found a very low energy pathway for alkoxysilane migration along the same monolayer. © 2012 American Chemical Society.

  15. Theoretical investigation of the interaction between aromatic sulfur compounds and [BMIM](+)[FeCl4](-) ionic liquid in desulfurization: A novel charge transfer mechanism. (United States)

    Li, Hongping; Zhu, Wenshuai; Chang, Yonghui; Jiang, Wei; Zhang, Ming; Yin, Sheng; Xia, Jiexiang; Li, Huaming


    In this work, interaction nature between a group of aromatic sulfur compounds and [BMIM](+)[FeCl4](-) have been investigated by density functional theory (DFT). A coordination structure is found to be critical to the mechanism of extractive desulfurization. Interaction energy and extractive selectivity follow the order: thiophene (TH)ionic liquid, but steric hindrance effects of some alkylic derivatives (e.g. 2,7-dimethylbenzothiophene) lead to a weaker interaction with ionic liquid. The mechanism of extractive desulfurization is attributed to the charge transfer effect. During extractive desulfurization, electrons on aromatic sulfur compounds transfer into the Lewis part of ionic liquid, namely, [FeCl4](-). Furthermore, it is better to consider the Lewis acidity of Fe-containing ionic liquid by the whole unit (such as [FeCl4](-) and aromatic sulfur compounds (X)) rather than only Fe or S atom.


    Directory of Open Access Journals (Sweden)

    I. R. Gulakov


    Full Text Available A mathematical model of asynchronous optical communication channel with a photon counter applied as a receiving module has been built. The expression for calculating of data throughput of this channel has been obtained. As a result of implemented experimental investigations it has been established that the data throughput of asynchronous optical communication channel containing a photon counter on the basis of avalanche photodetector as a receiving module depends on optical radiation and photodetector supply voltage.

  17. Microwave Spectroscopic Investigations of the C-H\\cdotsπ Containing Complexes CH_2F_2\\cdotsPROPYNE and CH_2ClF\\cdotsPROPYNE (United States)

    Peebles, Rebecca A.; Peebles, Sean A.; Christenholz, Cori L.; Ernst, Anthony A.; Dhahir, Yasser J.


    The spectra of the CH_2F_2\\cdotspropyne and CH_2ClF\\cdotspropyne complexes have been studied by chirped-pulse and resonant cavity Fourier-transform microwave spectroscopy and by ab initio calculations at the MP2/6-311++G(2d,2p) level. Both complexes contain C-H\\cdotsπ contacts, with the halogen atoms angled towards the methyl group end of the propyne. While CH_2F_2\\cdotspropyne has C_s symmetry, CH_2ClF\\cdotspropyne has C_1 symmetry, with the fluorine and chlorine atoms straddling the propyne. Investigation of four single ^{13}C and the DC≡CCH_3 isotopologues in CH_2F_2\\cdotspropyne has allowed a detailed structural determination, while only the ^{35}Cl and ^{37}Cl isotopologues have so far been assigned for CH_2ClF\\cdotspropyne. Experimental data will be compared with ab initio results and with the analogous acetylene complexes, both of which have C_s symmetry structures, with double C-H\\cdotsπ interactions.

  18. Effect of the pos-deposition annealing with CdCl2 on the optical, structural and morphological properties of CdTe-films grown by CSS (United States)

    Ricárdez-Jiménez, C.; Pérez-Hernández, G.; Pantoja-Enríquez, J.; Escobar-Morales, B.; Angulo-Córdova, Q.; Díaz-Flores, L. L.; Hernández-Torres, M. E.; Gracia-Jiménez, J. M.; Silva-González, N. R.; Mathew, X.


    A set of CdTe films grown by the CSS method were annealed in aCdCl2 atmosphere of during 5 min at 345, 365, 385, 405, 425, 435, 445 and 455 °C. The films were characterized before and after annealing by the SEM, EDS, X-ray, optical absorption and photoluminescence (PL) techniques. As the annealing temperature is increased a tendency to improve the Cd/Te ratio is observed. After the thermal treatment at 430 °C the films reach the stoichiometry. A deviation from stoichiometry appears again for annealing temperatures higher than 430 °C. The PL spectra of the films at 6.5 K exhibit two emission bands, one corresponds to the defects energy levels band (1.4-1.5 eV) and the other is located in the interval from 1.564 to 1.584 eV (pA). For annealing temperatures higher than 430 °C an increment in the intensity and energy position of pA is observed, while for annealing temperatures less than 430 °C the behavior is irregular. In the emission mechanisms of pA the expected impurities and/or native defects in the material such as the VTe, VCdClTe, CdTe and ClTe are involved.

  19. Investigating collagen self-assembly with optical tweezers microrheology (United States)

    Forde, Nancy; Shayegan, Marjan; Altindal, Tuba

    Collagen is the fundamental structural protein in vertebrates. Assembled from individual triple-helical proteins to make strong fibres, collagen is a beautiful example of a hierarchical self-assembling system. Using optical tweezers to perform microrheology measurements, we explore the dynamics of interactions between collagens responsible for their self-assembly and examine the development of heterogeneous mechanics during assembly into fibrillar gels. Telopeptides, short non-helical regions that flank the triple helix, have long been known to facilitate fibril self-assembly. We find that their removal not only slows down fibril nucleation but also results in a significant frequency-dependent reduction in the elastic modulus of collagens in solution. We interpret these results in terms of a model in which telopeptides facilitate transient intermolecular interactions, which enhance network connectivity in solution and lead to more rapid assembly in fibril-forming conditions. Current address: Department of Physics, McGill University.

  20. Investigation of diffractive optical element femtosecond laser machining

    Energy Technology Data Exchange (ETDEWEB)

    Chabrol, Grégoire R., E-mail: [ECAM Strasbourg-Europe, Espace Européen de l’entreprise, 2, rue de Madrid – 67300 SCHILTIGHEIM, CS. 20013, 67012 Strasbourg CEDEX (France); Laboratoire des Sciences de l’Ingénieur, de l’Informatique et de l’Imagerie (ICube), UDS-CNRS, UMR 7357, 300 bld Sébastien Brant, CS 10413, 67412 Illkirch cedex (France); Ciceron, Adline [ECAM Strasbourg-Europe, Espace Européen de l’entreprise, 2, rue de Madrid – 67300 SCHILTIGHEIM, CS. 20013, 67012 Strasbourg CEDEX (France); Laboratoire des Sciences de l’Ingénieur, de l’Informatique et de l’Imagerie (ICube), UDS-CNRS, UMR 7357, 300 bld Sébastien Brant, CS 10413, 67412 Illkirch cedex (France); Twardowski, Patrice; Pfeiffer, Pierre [Laboratoire des Sciences de l’Ingénieur, de l’Informatique et de l’Imagerie (ICube), UDS-CNRS, UMR 7357, 300 bld Sébastien Brant, CS 10413, 67412 Illkirch cedex (France); Télécom Physique Strasbourg – Pôle API – 300 Bd Sébastien Brant – CS 10413, Illkirch Graffenstaden F 67400 (France); and others


    Highlights: • A method for rapid manufacturing of optical diffractive element in BK7 is proposed. • A binary grating in BK7 was successfully machined by femtosecond laser pulses. • Process relying on nonlinear absorption in the dielectric due to photoionization. • The binary grating was analysed by SEM and interferometric microscopy. • Simulations by Fourier modal method supported the measured diffractive efficiency. - Abstract: This paper presents an explorative study on the machining of diffractive optical elements (DOEs) in transparent materials using a femtosecond laser source. A simple form of DOE, a binary phase grating with a period of 20.85 μm (σ = 0.5 μm), a groove depth and width of 0.7 μm (σ = 0.2 μm) and 8.8 μm (σ = 0.5 μm) respectively, was successfully machined in BK7. The topographic characteristics were measured by white light interferometry and scanning electron microscopy (SEM). The processing was carried out on high precision stages with an ultrafast fibre laser (350 fs) emitting a 343 nm pulse focused onto the sample with a stationary microscope objective. A diffracted efficiency of 27%, obtained with a spectro goniometer, was corroborated by the theoretical results obtained by the Fourier modal method (FMM), taking into account the measured topographic values. These encouraging results demonstrate that high-speed femtosecond laser manufacturing of DOE in bulk glasses can be achieved, opening the way to rapid prototyping of multi-layered-DOEs.

  1. Synthesis, structural and optical characterization of APbX3 (A=methylammonium, dimethylammonium, trimethylammonium; X=I, Br, Cl) hybrid organic-inorganic materials (United States)

    Mancini, Alessandro; Quadrelli, Paolo; Amoroso, Giuseppe; Milanese, Chiara; Boiocchi, Massimo; Sironi, Angelo; Patrini, Maddalena; Guizzetti, Giorgio; Malavasi, Lorenzo


    In this paper we report the synthesis, the crystal structure and the optical response of APbX3 (A=MA, DMA, and TMA; X=I, Br) hybrid organic-inorganic materials including some new phases. We observe that as the cation group increases in size, the optical absorption edge shifts to higher energies with energy steps which are systematic and independent on the anion. A linear correlation between the optical bad gap and the tolerance factor has been shown for the series of samples investigated.

  2. Thermal and optical efficiency investigation of a parabolic trough collector

    Directory of Open Access Journals (Sweden)

    C. Tzivanidis


    Full Text Available Solar energy utilization is a promising Renewable Energy source for covering a variety of energy needs of our society. This study presents the most well-known solar concentrating system, the parabolic trough collector, which is operating efficiently in high temperatures. The simulation tool of this analysis is the commercial software Solidworks which simulates complicated problems with an easy way using the finite elements method. A small parabolic trough collector model is designed and simulated for different operating conditions. The goal of this study is to predict the efficiency of this model and to analyze the heat transfer phenomena that take place. The efficiency curve is compared to a one dimensional numerical model in order to make a simple validation. Moreover, the temperature distribution in the absorber and inside the tube is presented while the heat flux distribution in the outer surface of the absorber is given. The heat convection coefficient inside the tube is calculated and compared with the theoretical one according to the literature. Also the angle efficiency modifier is calculated in order to predict the thermal and optical efficiency for different operating conditions. The final results show that the PTC model performs efficiently and all the calculations are validated.

  3. Modelling, structural, thermal, optical and vibrational studies of a new organic–inorganic hybrid material (C$_5$H$_{16}$N$_2$)Cd$_{1.5}$Cl$_5$

    Indian Academy of Sciences (India)



    Chemical preparation, theoretical calculations, X-ray single-crystal diffraction, thermal analysis, electrochemical measurements, IR, Raman and UV spectroscopic investigations of a novel organic–inorganic hybridmaterial (C$_5$H$_{16}$N$_2$)Cd$_{1.5}$Cl$_5$ are described. The structure provides a new interesting example of infinite inorganic chains of [Cd$_{1.5}$Cl$_5$]$^{2n}_n$− following the a crystallographic direction. The [Cd$_{1.5}$Cl$_5$]$^{2−}$ anions are interconnected by N–H$\\cdots$Cl hydrogen bonds. The Hirshfeld surface and associated fingerprint plots of the compound are presented to explore the nature of intermolecular interactions and their relative contributions in building the solid-state architecture. IR and Raman spectra are reported and discussed on the basis of group theoretical analysis and quantum chemical density functional theory (DFT) calculation. The molecular HOMO–LUMO compositions and their respective energy gaps are also drawn to explain the activity of our compound. Thermal analysis reveals the anhydrouscharacter of the compound.

  4. The investigation of acute optic neuritis: a review and proposed protocol. (United States)

    Petzold, Axel; Wattjes, Mike P; Costello, Fiona; Flores-Rivera, Jose; Fraser, Clare L; Fujihara, Kazuo; Leavitt, Jacqueline; Marignier, Romain; Paul, Friedemann; Schippling, Sven; Sindic, Christian; Villoslada, Pablo; Weinshenker, Brian; Plant, Gordon T


    Optic neuritis is an inflammatory optic neuropathy that affects many patients with multiple sclerosis (MS) at some point during their disease course. Differentiation of acute episodes of MS-associated optic neuritis from other autoimmune and inflammatory optic neuropathies is vital for treatment choice and further patient management, but is not always straightforward. Over the past decade, a number of new imaging, laboratory and electrophysiological techniques have entered the clinical arena. To date, however, no consensus guidelines have been devised to specify how and when these techniques can be most rationally applied for the diagnostic work-up of patients with acute optic neuritis. In this article, we review the literature and attempt to formulate a consensus for the investigation of patients with acute optic neuritis, both in standard care and in research with relevance to clinical treatment trials.

  5. Investigation of 160 Gbit/s optical communication systems

    DEFF Research Database (Denmark)

    Xu, Zhenbo


    Gbit/s single channel experiment, two dispersion maps are investigated in transmission spans, namely symmetrical and post dispersion compensation maps taking advantage of the benefit from Raman amplification. The post compensation map offers best power tolerance. WDM systems based on distributed Raman...

  6. Surface topology investigation for ancient coinage assessment using optical interferometry (United States)

    Grynszpan, R. I.; Pastol, J. L.; Lesko, S.; Paris, E.; Raepsaet, C.

    In order to demonstrate the capabilities of white-light interferometry depth profiling (WLI-DP) for ancient coinage assessment, we investigated a series of notorious 1786 gold coins, bearing Louis XVI's `horned' effigy, and allegedly minted in Strasbourg. Scanning electron microscopy as well as WLI-DP observations unambiguously indicate that both previously differentiated `single'- and `double'-horned varieties originated from a unique minting tool. Moreover, from topological measurements, we infer that `single-horned' coins, rather than wearing out into `double-horned' coins, proceeded from the latter variety during minting by progressive failure of an already altered die. Whereas present observations do not exclude initial forgery, they suggest that protrusions resulted from progressive incidental in-service die deterioration.

  7. Investigation of outer valence orbital of CF2Cl2 by a new type of electron momentum spectrometer

    Institute of Scientific and Technical Information of China (English)

    Ning Chuan-Gang; Ren Xue-Guang; Deng Jing-Kang; Su Guo-Lin; Zhang Shu-Feng; Huang Feng; Li Gui-Qin


    Electronic states of CF2Cl2 (dichlorodifluoromethane, Freon 12) have been studied using a new type of electron momentum spectrometer with a very high efficiency at an impact energy of 1200 eV plus binding energy. The experimental electron momentum profiles are compared with the density functional theory (DFT) and Hartree-Fock (HF)calculations. The relationship between orbital assignments in different coordinate systems is discussed. A new method of difference analysis based on the new type of electron momentum spectrometer is used to clarify the ambiguities regarding the orbital ordering.

  8. Study of NaCl:Mn{sup 2+} nanostructures in the Suzuki phase by optical spectroscopy and atomic force microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Mejía-Uriarte, E.V., E-mail: [Laboratorio de Fotónica de Microondas, Centro de Ciencias Aplicadas y Desarrollo Tecnológico, Universidad Nacional Autónoma de México, AP 70-186, C.P. 04510, D.F. México (Mexico); Kolokoltsev, O. [Laboratorio de Fotónica de Microondas, Centro de Ciencias Aplicadas y Desarrollo Tecnológico, Universidad Nacional Autónoma de México, AP 70-186, C.P. 04510, D.F. México (Mexico); Navarrete Montesinos, M. [Instituto de Ingeniería, Universidad Nacional Autónoma de México, D.F. México (Mexico); Camarillo, E.; Hernández A, J.; Murrieta S, H. [Instituto de Física, Universidad Nacional Autónoma de México, AP 20-364, C.P. 01000, D.F. México (Mexico)


    NaCl:Mn{sup 2+} nanostructures in the Suzuki phase have been studied by fluorescence (emission and excitation) spectroscopy and atomic force microscopy (AFM) as a function of temperature. The “as-grown” samples give rise to two broad emission bands that peak at 508 (green emission) and 610 nm (red emission). The excitation spectrum shows peaks at 227 nm and 232 nm for emission wavelengths at 508 nm and 610 nm, respectively. When the samples are heated continuously from room temperature up to 220 °C, the green emission (associated to the excitation peak at 227 nm) disappears at a temperature close to 120 °C, whilst only the red emission remains, which is characteristic of manganese ions. AFM images on the (0 0 1) surface (freshly cleaved) show several conformations of nanostructures, such as disks of 20–50 nm in diameter. Particularly, the images also reveal nanostructures with rectangular shape of ~280×160 nm{sup 2} and ~6 nm height; these are present only in samples with green emission associated to the Suzuki phase. Then, the evidence suggests that this topographic configuration might be related to the interaction with the first neighbors and the next neighbors, according to the configuration that has been suggested for the Suzuki phase. - Highlights: • NaCl:Mn{sup 2+} single crystals in the Suzuki phase contain rectangular nanostructures. • Double emission of manganese ions: green (508 nm) and red (610 nm) bands. • The excitation peak at 227 nm is attributed to rectangular nanostructures. • The green emission band associated to Suzuki phase is extinguished at 120 °C.

  9. Effects of CdCl{sub 2} treatment on the recrystallization and electro-optical properties of CdTe thin films

    Energy Technology Data Exchange (ETDEWEB)

    Moutinho, H.R.; Al-Jassim, M.M.; Levi, D.H.; Dippo, P.C.; Kazmerski, L.L. [National Renewable Energy Laboratory, Golden, Colorado 80401 (United States)


    The effects of CdCl{sub 2} processing on the physical and electro-optical properties of CdTe were evaluated for thin films produced by physical vapor deposition and close-spaced sublimation (CSS). Two substrates (CdS and Indium{endash}tin{endash}oxide) were used with the physical vapor deposition (PVD) films specifically to isolate the effects of the Cd(S{sub x}Te{sub 1{minus}x}) alloy formed during the treatment of films deposited on CdS. The samples were analyzed by x-ray diffraction (XRD), atomic force microscopy (AFM), and photoluminescence. The observed changes in microstructure were caused by recrystallization, which consisted of the nucleation and development of a new CdTe structure and subsequent grain growth. Nevertheless, for these processes to take place, it was necessary that enough lattice-strain energy was available in the films. For this reason, PVD films did recrystallize, while CSS films did not. For the first time, recrystallization was observed directly in AFM images of CdTe films and confirmed by XRD analysis, which indicated the existence of two lattice parameters in PVD samples treated at 350{degree}C. For samples treated at 400{degree}C, the CdCl{sub 2} treatment improved the minority-carrier lifetime of the films by more than one order of magnitude. This improvement was attributed to the elimination of deep defect levels within the band gap of the CdTe films as a result of the treatment. The sulfur diffusion into CdTe films deposited on CdS, during the CdCl{sub 2} treatment at 400{degree}C, strongly affected the defect structure.

  10. Optical investigations of AlSi-SiC composites subjected to laser CO 2 annealing (United States)

    Jaglarz, Janusz; Grabowski, Andrzej


    The optical study of the AlSi/SiC composite materials before and after laser annealing has been performed. They concerned total and diffuse reflectance measurements obtained by the means of integrating sphere in the spectral range 250-2500 nm, measurements of intensity of scattered light as a function of scattering angle ( BRDF method) and ellipsometric measurements performed in the range 190-1700 nm. For determination of optical constants, the Kramers-Krönig dispersion relation has been applied. Obtained results had great differences of optical properties alloys before and after laser annealing. For investigated composites roughness and correlation lengths of studied surfaces have been determined. Moreover, optical measurements allowed concluding the light scattering being a result of interaction of light with surface topography and material scattering appeared due to variation of optical constants on surfaces of AlSi/SiC composites.

  11. Theoretical and numerical investigations of sub-wavelength diffractive optical structures

    DEFF Research Database (Denmark)

    Dridi, Kim


    The work in this thesis concerns theoretical and numerical investigations of sub-wavelength diffractive optical structures, relying on advanced two-dimensional vectorial numerical models that have applications in Optics and Electromagnetics. Integrated Optics is predicted to play a major role...... in future technologies. For this to come true, more advanced optical signal processing must be achieved in miniaturized multifunctional components which should enable optimal light control and light localization. These components have complex subwavelength geometries and material distributions......, such as in dielectric waveguides with gratings and periodic media or photonic crystal structures. The vectorial electromagnetic nature of light is therefore taken into account in the modeling of these diffractive structures. An electromagnetic vector-field model for optical components design based on the classical...

  12. Terahertz Generation in an Electrically Biased Optical Fiber: A Theoretical Investigation

    Directory of Open Access Journals (Sweden)

    Montasir Qasymeh


    Full Text Available We propose and theoretically investigate a novel approach for generating terahertz (THz radiation in a standard single-mode fiber. The optical fiber is mediated by an electrostatic field, which induces an effective second-order nonlinear susceptibility via the Kerr effect. The THz generation is based on difference frequency generation (DFG. A dispersive fiber Bragg grating (FBG is utilized to phase match the two interacting optical carriers. A ring resonator is utilized to boost the optical intensities in the biased optical fiber. A mathematical model is developed which is supported by a numerical analysis and simulations. It is shown that a wide spectrum of a tunable THz radiation can be generated, providing a proper design of the FBG and the optical carriers.

  13. Development and investigation of a CPV module with Cassegrain mirror optics (United States)

    Dreger, Max; Wiesenfarth, Maike; Kisser, Arne; Schmid, Tobias; Bett, Andreas W.


    One approach to concentrate the sunlight in concentrating photovoltaic (CPV) modules is using Cassegrain mirror optics. The advantage is that a passively cooled solar cell can be mounted to a large heat spreader that does not shade the primary optics. In addition, the height of the module, hence weight, can be low. The design was selected on the basis of the results of a design study comparing different CPV module approaches presented in [1]. In this work, we present the development of a new prototype micro dish module. First results of the characterization are shown. Besides of the electrical performance, a machined optics and an injection molded was investigated regarding sensitivity to misalignment errors between the optical elements as well as measurement of the acceptance angle in- and outdoors. The machined optics was used as reference.

  14. Investigations of GMAW plasma by optical emission spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Zielinska, S [Instytut Fizyki im. Mariana Smoluchowskiego, Uniwersytet Jagiellonski, ulica Reymonta 4, 30-059 Krakow (Poland); Musiol, K [Instytut Fizyki im. Mariana Smoluchowskiego, Uniwersytet Jagiellonski, ulica Reymonta 4, 30-059 Krakow (Poland); Dzierzega, K [Instytut Fizyki im. Mariana Smoluchowskiego, Uniwersytet Jagiellonski, ulica Reymonta 4, 30-059 Krakow (Poland); Pellerin, S [LASEP, Faculte des Sciences-Bourges, Universite d' Orleans, BP 4043, 18028 Bourges Cedex (France); Valensi, F [LASEP, Faculte des Sciences-Bourges, Universite d' Orleans, BP 4043, 18028 Bourges Cedex (France); Izarra, Ch de [LASEP, Faculte des Sciences-Bourges, Universite d' Orleans, BP 4043, 18028 Bourges Cedex (France); Briand, F [CTAS - Air Liquide Welding, Rue des Epluches, Saint Ouen l' Aumone (France)


    We report on investigations of gas metal arc welding plasma operated in pure argon and in a mixture of argon and CO{sub 2} at a dc current of 326 A. The spatially resolved electron densities and temperatures were directly obtained by measuring the Stark widths of the Ar I 695.5 nm and Fe I 538.3 nm spectral lines. Our experimental results show a reduction of the plasma conductivity and transfer from spray arc to globular arc operation with increasing CO{sub 2} concentration. Although the electron density n{sub e} increases while approaching the core of the plasma in the spray-arc mode, a drop in the electron temperature T{sub e} is observed. Moreover, the maximum T{sub e} that we measure is about 13 000 K. Our experimental results differ from the Haidar model where T{sub e} is always maximum on the arc axis and its values exceed 20 000 K. These discrepancies can be explained as a result of underestimation of the amount of metal vapours in the plasma core and of the assumption of local thermal equilibrium plasma in the model.

  15. DFT(B3LYP/LanL2DZ), non-linear optical and electrical studies of a new hybrid compound: [C6H10(NH3)2]CoCl4·H2O (United States)

    Tounsi, Amal; Hamdi, Besma; Zouari, Ridha; Ben Salah, Abdelhamid


    A new organic-inorganic material [C6H10(NH3)2]CoCl4·H2O was reported. The title compound was synthesized at room temperature by slow evaporation and then characterized by a single X-ray diffraction, spectroscopic measurements, thermal analysis and dielectric technique. It crystallizes in the non-centrosymmetric space group Pna21 with the following unit cell parameters: a=12.5328(1) Å, b=9.0908(1) Å, c=11.7440(1) and α=β=γ=90°. The structure can be described by the alternation of two different cationic-anionic layers. It consists of isolated H2O, isolated [CoCl4]2- tetrahedral anions and diammoniumcyclohexane [C6H10(NH3)2]2+ cations, which are connected via N-H…Cl, N-H…O and O-H…N hydrogen bonds. The Hirshfeld surface analysis was conducted to investigate intermolecular interactions and associated 2D fingerprint plots, revealing the relative contribution of these interactions in the crystal structure quantitatively. Theoretical calculations were performed using DFT/B3LYP/LanL2DZ method for studying the molecular structure and vibrational spectra and especially to examine the non-linear optical behavior of the compound. Solid state 13C NMR spectrum shows three signals correspond to three different carbon environments. Thermal analysis discloses a phase transition at the temperature 315 K and the evaporation of water molecule at 327 K. A detailed dielectric study was reported and shows a good agreement with thermal measurements.

  16. Structural, electronic and optical properties of Cu-doped ZnO: experimental and theoretical investigation (United States)

    Horzum, S.; Torun, E.; Serin, T.; Peeters, F. M.


    Experiments are supplemented with ab initio density functional theory (DFT) calculations in order to investigate how the structural, electronic and optical properties of zinc oxide (ZnO) thin films are modified upon Cu doping. Changes in characteristic properties of doped thin films, that are deposited on a glass substrate by sol-gel dip coating technique, are monitored using X-ray diffraction (XRD) and UV measurements. Our ab initio calculations show that the electronic structure of ZnO can be well described by DFT+U/? method and we find that Cu atom substitutional doping in ZnO is the most favourable case. Our XRD measurements reveal that the crystallite size of the films decrease with increasing Cu doping. Moreover, we determine the optical constants such as refractive index, extinction coefficient, optical dielectric function and optical energy band gap values of the films by means of UV-Vis transmittance spectra. The optical band gap of ZnO the thin film linearly decreases from 3.25 to 3.20 eV at 5% doping. In addition, our calculations reveal that the electronic defect states that stem from Cu atoms are not optically active and the optical band gap is determined by the ZnO band edges. Experimentally observed structural and optical results are in good agreement with our theoretical results.

  17. Feasibility investigation and design study of optical well logging methods for high temperature geothermal wells

    Energy Technology Data Exchange (ETDEWEB)

    Swanson, R.K.; Anderson, R.E.; Ash, J.I.; Beissner, R.E.; Smith, V.D.


    The objective of this project was exploration of a novel approach to high temperature well logging, based on a system of optical transducers and an optical transmission line both theoretically capable of operation to at least 600/sup 0/C. The scope of the work involved the accomplishment of ten specific tasks. These had as their objective the determination of feasibility, and identification of major problem areas, in the implementation of continuous temperature logging of geothermal wells using optical techniques. The following tasks are reported: literature review and data compilation, measurement of fiber properties production fiber procurement, investigation of methods of fiber termination, cable design and fabrication, and sensor and system studies. (MHR)

  18. Further investigations into pulsed optically stimulated luminescence from feldspars using blue and green light

    DEFF Research Database (Denmark)

    Ankjærgaard, Christina; Jain, Mayank; Kalchgruber, R.;


    The purpose of this paper is to investigate characteristics of luminescence signals resulting from pulsed optical stimulation of feldspars and thereby to understand the underlying processes giving rise to the signal. Fourteen different feldspar specimens were investigated using time-resolved opti...

  19. Experimental investigation of parallel optical data storage using pyrrylfulgide photochromic material

    Institute of Scientific and Technical Information of China (English)

    LEI Ming; CHEN Guofu; YAO Baoli; CHEN Yi; HAN Yong; WANG Yingli; MENKE Neimule; ZHENG Yuan; WANG Congmin; FAN Meigong


    The optical storage characteristics of a new kind of organic photochromic material--pyrrylfulgide were experimentally investigated in the established parallel optical data storage system. Using the pyrrylfulgide/PMMA film as a photon-mode recording medium, micro-images and encoded binary digital data were recorded, readout and erased in this parallel system. The storage density currently reaches 3×107 bit/cm2. The recorded information on the film can be kept for years in darkness at room temperature.

  20. Software and Hardware System for the Investigation of the Thin Film Optical Properties

    Directory of Open Access Journals (Sweden)

    O.V. Fedchenko


    Full Text Available Using Torhlabs optical elements and graphic software development system LabVIEW 2010 the software and hardware automation system for the investigation of the optical properties of multilayer film systems was built. The joint genetic algorithm was suggested to process experimental data of Null-ellipsometry and X-ray reflectometry. It was shown that the proposed technique lets one simulate phase transitions, diffusion processes and interface blurring in multilayer film systems very accurate for different computational theoretic models.

  1. Adsorption of H2, Cl2, and HCl molecules on α-Cr2O3(0001) surfaces: A density functional theory investigation (United States)

    Nigussa, K. N.; Nielsen, K. L.; Borck, Ø.; Støvneng, J. A.


    Density functional theory calculations show that H2, Cl2, and HCl molecules chemisorb dissociatively on the Cr2O3(0001) surface, which can be terminated by Cr atoms, Chromyl groups (Cr=O), or O atoms. It is investigated that these molecules energetically prefer to adsorb dissociatively than in molecular form. Several dissociative adsorption sites have been considered for all the molecules on all the differently terminated surfaces and the corresponding adsorption energies are calculated. Dissociation energy barriers are estimated with the nudged elastic band method. Notable results from the dissociative adsorptions of Cl2 and H2 are the formation of a CrCl2 complex on the Cr terminated surface, and H2O complex on the O and the Cr=O terminated surfaces, and a H2O layer on the Cr=O terminated surface. Dissociative adsorption of HCl is less favored on the Cr=O and O terminated surfaces than on the Cr terminated surface.

  2. Prism coupling technique investigation of elasto-optical properties of thin polymer films (United States)

    Ay, Feridun; Kocabas, Askin; Kocabas, Coskun; Aydinli, Atilla; Agan, Sedat


    The use of thin polymer films in optical planar integrated optical circuits is rapidly increasing. Much interest, therefore, has been devoted to characterizing the optical and mechanical properties of thin polymer films. This study focuses on measuring the elasto-optical properties of three different polymers; polystyrene, polymethyl-methacrylate, and benzocyclobutane. The out-of-plane elastic modulus, refractive index, film thickness, and birefringence of thin polymer films were determined by means of the prism coupling technique. The effect of the applied stress on the refractive index and birefringence of the films was investigated. Three-dimensional finite element method analysis was used so as to obtain the principal stresses for each polymer system, and combining them with the stress dependent refractive index measurements, the elasto-optic coefficients of the polymer films were determined. It was found that the applied stress in the out-of-plane direction of the thin films investigated leads to negative elasto-optic coefficients, as observed for all the three thin polymer films.

  3. Investigating the Fabrication Imperfections of Plasmonic Nanohole Arrays and Its Effect on the Optical Transmission Spectra

    Directory of Open Access Journals (Sweden)

    Amr M. Mahros


    Full Text Available We investigate the extraordinary optical transmission spectra of thin gold films perforated with imperfect nanohole arrays using the finite difference time domain (FDTD method. Exponential shapes for the nanohole sidewalls are used. To the best of our knowledge, such investigation of transmission spectra of imperfect nanohole arrays has not previously been demonstrated. It was found that the asymmetry between the two openings of the circular nanoholes or bending to their sidewalls strongly modifies both the intensity and resonance positions of the transmission spectra. Furthermore, the results of this study assist in explaining the technicality of extraordinary optical transmission phenomenon and why some experimental results on transmission differ from those expected.

  4. Investigation of variable spindle speed in slow tool servo-based turning of noncircular optical components (United States)

    Huang, Weihai; Yu, Deping; Chen, Dongsheng; Zhang, Min; Liu, Jinguang; Yao, Jin


    Ultra-precision noncircular optical components, e.g. hyperbolic quadrupole in mass spectrometer, can be machined by diamond turning assisted by slow tool servo (STS). However, the bandwidth of STS is usually small, which limits the STS's capability in following the required tool path, leading to a large form error. To reduce the form error, this paper proposes an approach to apply variable spindle speed (VSS) to STS-based turning. Design of the VSS trajectory based on the noncircular profile of the optical component was investigated in detail. To validate the proposed approach, simulation on the application of VSS in the STS-based turning process was established and applied to the machining of typical noncircular optical components. Simulation results show that the proposed approach is effective in reducing the requirement on the bandwidth of the STS, resulting in higher form accuracy of the machined noncircular optical components.

  5. Investigation of all-optical regeneration based on self-phase modulation in microstructured fibers

    Institute of Scientific and Technical Information of China (English)

    WEI Yan-fen; XU Yong-zhao; Zhang Xia; HUANG Yong-qing; REN Xiao-min


    All-optical regeneration based on self-phase modulation in microstructured fibers is studied. The effects of pulse peak power into the fiber,pulse width and filter parameters on the performance of the regenerator are investigated. The effects of normal dispersion and anomalous dispersion of the microstructured fiber on optical regeneration are compared. The numerical results show that optical regeneration can be achieved by using microstructured fibers with normal dispersion or anomalous dispersion,but the normal dispersion decreases the oscillatory structure in the broadened spectra and obtain a better regenerator transfer function. In order to achieve optical regeneration,the input peak power into the microstructured fiber and the filter parameters need to meet certain requirements. By optimizing those parameters,a better regeneration result can be obtained.

  6. Investigation of the CH3Cl + CN(-) reaction in water: Multilevel quantum mechanics/molecular mechanics study. (United States)

    Xu, Yulong; Zhang, Jingxue; Wang, Dunyou


    The CH3Cl + CN(-) reaction in water was studied using a multilevel quantum mechanics/molecular mechanics (MM) method with the multilevels, electrostatic potential, density functional theory (DFT) and coupled-cluster single double triple (CCSD(T)), for the solute region. The detailed, back-side attack SN2 reaction mechanism was mapped along the reaction pathway. The potentials of mean force were calculated under both the DFT and CCSD(T) levels for the reaction region. The CCSD(T)/MM level of theory presents a free energy activation barrier height at 20.3 kcal/mol, which agrees very well with the experiment value at 21.6 kcal/mol. The results show that the aqueous solution has a dominant role in shaping the potential of mean force. The solvation effect and the polarization effect together increase the activation barrier height by ∼11.4 kcal/mol: the solvation effect plays a major role by providing about 75% of the contribution, while polarization effect only contributes 25% to the activation barrier height. Our calculated potential of mean force under the CCSD(T)/MM also has a good agreement with the one estimated using data from previous gas-phase studies.

  7. Transient resonance Raman spectroscopy and density functional theory investigation of iso-CHBr 2Cl and iso-CCl 3Br photoproducts produced following ultraviolet excitation of CHBr 2Cl and CCl 3Br


    Zheng, X; Lee, CW; Li, YL; Fang, WH; Phillips, DL


    Two polyhalomethanes that contain bromine and chlorine atoms (CHBr 2Cl and CCl 2Br) were studied. Transient resonance Raman spectra were obtained for the photoproducts produced after ultraviolet excitation of CHBr 2Cl and CCl 3Br in room temperature solutions and density functional theory calculations for species proposed to be products of the photodissociation reactions in the solution phase. It was found that the iso-CHBrCl-Br and iso-CHClBr-Br species are formed following ultraviolet excit...

  8. Simulation of continuously logical ADC (CL ADC) of photocurrents as a basic cell of image processor and multichannel optical sensor systems (United States)

    Krasilenko, Vladimir G.; Nikolskyy, Aleksandr I.; Lazarev, Alexander A.; Krasilenko, Oksana V.; Krasilenko, Irina A.


    The paper considers results of design and modeling of continuously logical analog-to-digital converters (ADC) based on current mirrors for image processor and multichannel optical sensor systems with parallel inputs-outputs. For such multichannel serial-parallel analog-to-digital converters (SP ADC) it is needed base photoelectron cells, which are considered in paper. Its have a number of advantages: high speed and reliability, simplicity, small power consumption, high integration level for linear and matrix structures. We show design of the continuously logical ADC of photocurrents and its base digit cells (ABC) and its simulations. We consider CL ADC for Gray and binary codes. Each channel of the structure consists of several base digit cells (ABC) on 20-30 CMOS FETs and one photodiode. The supply voltage of the ABC is 1-3.3V, the range of an input photocurrent is 0.1 - 10μA, the transformation time is 30ns at 5-8 bit binary or Gray codes, power consumption is about 1mW. One channel of ADC with iteration is based on one ABC-3(G) and SHD, and it has only 40 CMOS transistors. The general power consumption of the ADC, in this case, is only 50-100μW, if the maximum input current is 1μA. The CL ADC opens new prospects for realization of linear and matrix image processor and photo-electronic structures with picture operands, which are necessary for neural networks, digital optoelectronic processors, neural-fuzzy controllers, and so forth.

  9. Study of electronic structure, charge density, Fermi energy and optical properties of Cs{sub 2}KTbCl{sub 6} and Cs{sub 2}KEuCl{sub 6}

    Energy Technology Data Exchange (ETDEWEB)

    Azam, Sikander, E-mail: [Institute of Complex Systems, FFPW, CENAKVA, South Bohemia University in CB, Nove Hrady 37333 (Czech Republic); Reshak, A.H. [Institute of Complex Systems, FFPW, CENAKVA, South Bohemia University in CB, Nove Hrady 37333 (Czech Republic); Center of Excellence Geopolymer and Green Technology, School of Material Engineering, University Malaysia Perlis, 01007 Kangar, Perlis (Malaysia)


    Through the assist of the full-potential linear augmented plane wave (FPLAPW) method, the calculations of the electronic band structure, density of states, charge density, Fermi energy and regularity dependent dielectric functions of Cs{sub 2}KTbCl{sub 6} and Cs{sub 2}KEuCl{sub 6} are reported. This study shows that the nature of both these compounds is metallic. The generalized gradient approximations (GGA) exchange correlation potential was applied. The densities of states around Fermi level are frequently subjugated by Eu/Tb-f and DOS below Fermi level are subjugated by Eu/Tb-s/d, Cs-s, Cl-s and K-s/p. The value of the DOS at Fermi level N(E{sub F}) is 17.02 and 4.86 (states per unit cell per eV) for Cs{sub 2}KEuCl{sub 6} and Cs{sub 2}KTbCl{sub 6}. The bare electronic specific heat coefficient, is found to be 2.95 and 0.84 mJ/mol K{sup 2} for Cs{sub 2}KEuCl{sub 6} and Cs{sub 2}KTbCl{sub 6}, respectively. Three bands crossing the Fermi level along the Γ−A direction of Brillion zone of Cs{sub 2}KTbCl{sub 6} compound and one band crossing along the Γ−A direction of Brillion zone of Cs{sub 2}KEuCl{sub 6} compounds, to form the Fermi surface. There exists a strong hybridization between Tb/Eu-K-p and Cl-s K-s and at −5.0 and −4.0 eV.

  10. Applications of LIBS for determination of ionic species (NaCl) in electrical cables for investigation of electrical breakdown (United States)

    Gondal, M. A.; Shwehdi, M. H.; Khalil, A. A. I.


    The formation of water trees in high-voltage cables can wreak havoc to power systems. The water tree is produced within the high voltage cable insulator when impurities like sodium and magnesium present in the insulating material react with moist soil to form chlorides. This water tree causes electrical breakdown by short circuiting the metallic conductor and the earth. In this paper we use laser-induced breakdown spectroscopy (LIBS) to detect the potentially dangerous elements that form the water tree in the insulating cable. The LIBS system used for this work consists of the fundamental (1064 nm) of a Nd:YAG laser, four spectrometer modules that cover the visible and near-UV spectral ranges and an ICCD camera with proper delay and gating sequence. With this arrangement we were able to measure the elemental concentrations of trace metals present in the insulating cable. The concentrations measured with our LIBS system were counter checked by a standard technique like inductively coupled plasma (ICP) emission spectrometry. The maximum concentrations for ionic species such as Ba (455.40 nm), Ca (393.36 nm), Cr (267.71 nm), Fe (259.94 nm), Cl (542.3 nm), Mg (516.7 nm), Mn (257.61 nm), Na (589.59 nm) and Ti (334.18 nm) are 20.6, 43.2, 1.6, 148.4, 24.2, 22.1, 4.2, 39.56 and 4.35 ppm, respectively. The relative accuracy of our LIBS system for various elements as compared with the ICP method is in the range of 0.03-0.6 at 2.5% error confidence.

  11. Frontiers of Optical Spectroscopy Investigating Extreme Physical Conditions with Advanced Optical Techniques

    CERN Document Server

    Bartolo, Baldassare


    Advanced spectroscopic techniques allow the probing of very small systems and very fast phenomena, conditions that can be considered "extreme" at the present status of our experimentation and knowledge. Quantum dots, nanocrystals and single molecules are examples of the former and events on the femtosecond scale examples of the latter. The purpose of this book is to examine the realm of phenomena of such extreme type and the techniques that permit their investigations. Each author has developed a coherent section of the program starting at a somewhat fundamental level and ultimately reaching the frontier of knowledge in the field in a systematic and didactic fashion. The formal lectures are complemented by additional seminars.

  12. Investigation of bending loss in a single-mode optical fibre

    Indian Academy of Sciences (India)

    A Zendehnam; M Mirzaei; A Farashiani; L Horabadi Farahani


    Loss of optical power in a single-mode optical fibre due to bending has been investigated for a wavelength of 1550 nm. In this experiment, the effects of bending radius (4–15 mm, with steps of 1 mm), and wrapping turns (up to 40 turns) on loss have been studied. Twisting the optical fibre and its influence on power loss also have been investigated. Variations of bending loss with these two parameters have been measured, loss with number of turns and radius of curvature have been measured, and with the help of computer curve fitting method, semi-empirical relationships between bending loss and these two parameters have been found, which show good agreement with the obtained experimental results.

  13. Investigation on a replica step gauge for optical 3D scanning of micro parts

    DEFF Research Database (Denmark)

    Cantatore, Angela; De Chiffre, Leonardo; Carmignato, S.


    This work deals with investigation of the stability over time and surface cooperativeness of a calibration artefact intended for optical scanner verification. A replica step gauge with 11 grooves, made of bisacryl material for dental applications (luxabite) and previously fabricated was studied...

  14. Investigation of single and split injection strategies in an optical diesel engine


    Herfatmanesh, Mohammad Reza


    This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University, 22/12/2010. This study investigates the effects of a split injection strategy on combustion performance and exhaust emissions in a high speed direct injection optical diesel engine. The investigation is focused on the effects of injection timing, quantity, and the dwell angle between the injections using commercially available diesel fuel. Three different split injection strategies including ...

  15. Investigation of the power characteristics of a Gunn-diode quasi-optical generator


    Borodkin, A. I.; Bulgakov, B. M.; Chernyshov, I. Yu.


    The results of investigations of the power characteristics of a quasi-optical millimeter-wave Gunn diode generator are given. The efficiency of power output from an open resonator is investigated. It is shown that the impedances of a Gunn diode and an open resonator can be matched using a radial resonator. The conditions under which the Gunn diode provides maximum power into the load are studied.

  16. Investigation of the screen optics of thick CsI(Tl) detectors (United States)

    Howansky, Adrian; Peng, Boyu; Suzuki, Katsuhiko; Yamashita, Masanori; Lubinsky, A. R.; Zhao, Wei


    Flat panel imagers (FPI) are becoming the dominant detector technology for digital x-ray imaging. In indirect FPI, the scintillator that provides the highest image quality is Thallium (Tl) doped Cesium Iodide (CsI) with columnar structure. The maximum CsI thickness used in existing FPI is ~600 microns, due to concerns of loss in spatial resolution and light output with further increase in thickness. The goal of the present work is to investigate the screen-optics for CsI with thicknesses much larger than that used in existing FPI, so that the knowledge can be used to improve imaging performance in dose sensitive and higher energy applications, such as cone-beam CT (CBCT). Columnar CsI(Tl) scintillators up to 1 mm in thickness with different screen-optical design were investigated experimentally. Pulse height spectra (PHS) were measured to determine the Swank factor at x-ray energies between 25 and 75 keV, and to derive depth-dependent light escape efficiency i.e. gain. Detector presampling MTF, NPS and DQE were measured using a high-resolution CMOS optical sensor. Optical Monte Carlo simulation was performed to estimate optical parameters for each screen design and derive depth-dependent gain and MTF, from which overall MTF and DQE were calculated and compared with measured results. The depth-dependent imaging performance parameters were then used in a cascaded linear system model (CLSM) to investigate detector performance under screen- and sensor-side irradiation conditions. The methodology developed for understanding the optics of thick CsI(Tl) will lead to detector optimization in CBCT.

  17. Quantitative optical coherence microscopy for the in situ investigation of the biofilm (United States)

    Meleppat, Ratheesh Kumar; Shearwood, Christopher; Keey, Seah Leong; Matham, Murukeshan Vadakke


    This paper explores the potential of optical coherence microscopy (OCM) for the in situ monitoring of biofilm growth. The quantitative imaging of the early developmental biology of a representative biofilm, Klebsiella pneumonia (KP-1), was performed using a swept source-based Fourier domain OCM system. The growth dynamics of the KP-1 biofilms and their transient response under perturbation was investigated using the enface visualization of microcolonies and their spatial localization. Furthermore, the optical density (OD) and planar density of the biofilms are calculated using an OCM technique and compared with OD and colony forming units measured using standard procedures via the sampling of the flow-cell effluent.

  18. Investigation of Power8 processors for astronomical adaptive optics real-time control

    CERN Document Server

    Basden, Alastair


    The forthcoming Extremely Large Telescopes all require adaptive optics systems for their successful operation. The real-time control for these systems becomes computationally challenging, in part limited by the memory bandwidths required for wavefront reconstruction. We investigate new POWER8 processor technologies applied to the problem of real-time control for adaptive optics. These processors have a large memory bandwidth, and we show that they are suitable for operation of first-light ELT instrumentation, and propose some potential real-time control system designs. A CPU-based real-time control system significantly reduces complexity, improves maintainability, and leads to increased longevity for the real-time control system.

  19. Investigation of the effects of long duration space exposure on active optical system components (United States)

    Blue, M. D.


    This experiment was exposed to the space environment for 6 years on the Long Duration Exposure Facility (LDEF). It investigated quantitatively the effects of the long-duration space exposure on the relevant performance parameters of a representative set of electron-optic system components, including lasers, radiation detectors, filters, modulators, windows, and other related components. It evaluated the results and implications of the measurements indicating real or suspected degradation mechanisms. This information will be used to establish guidelines for the selection and use of components for space-based, electro-optic systems.

  20. Investigation of the in-solution relaxation of polymer optical fibre Bragg gratings

    DEFF Research Database (Denmark)

    Fasano, Andrea; Woyessa, Getinet; Janting, Jakob


    We investigate the response of PMMA microstructured polymer optical fibre Bragg gratings whenimmersed in methanol/water solutions. Overall we observe a permanent blue-shift in Bragg gratingwavelength after solvent evaporation. The main contribution in the resonance wavelength shift probably...... arisesfrom a permanent change in the size of the fibre, as already reported for high-temperature annealing ofpolymer optical fibres. As a consequence of the solution concentration dependence of the glass transitiontemperature of polymers, different methanol/water solutions lead to various degrees of frozen...

  1. Investigation of Optical and Luminescence Properties of Soda Lime Borate Glasses Doped with Sm3+ Ion

    Institute of Scientific and Technical Information of China (English)

    FALAK; Zaman; GUL; Rooh; NATTAPON; Srisittipokakun; JACKRAPONG; Kaewkhao


    This paper was to investigate the optical and luminescence properties of Sm3+ doped SLB glasses by a melt quenching technique. The optical and luminescence properties of the prepared glass samples were investigated via absorption and photoluminescence spectra, respectively. The related physical and optical parameters were also calculated. From optical absorption measurements, the transition 6H5/2 → 6P3/2 at 403 nm has a higher spectral intensity and is a hypersensitive transition. From photoluminescence spectra, four prominent emission spectra appear. The most intense band is located at 4G5/2 →6H9/2(599 nm), which is the characteristic emission range of Sm3+ ions with the reddish orange color. The experimental decay time of the 4G5/2 level of Sm3+ SLB glasses was determined. The decay time decreases from 1.367 to 0.333 ms with increasing the content of Sm3+. The color coordinates(x, y) of the prepared glasses passes through the reddish-orange region in the CIE 1931 diagram and are suitable for orange LEDs, optoelectronics, and solidstate lighting. The further investigation on the optimization of the dopant content in the SLB glasses was suggested.

  2. Experimental investigation of the thin fiber-optic hydrophone array based on fiber Bragg gratings (United States)

    Lavrov, Vladimir S.; Plotnikov, Mikhail Y.; Aksarin, Stanislav M.; Efimov, Mikhail E.; Shulepov, Vladimir A.; Kulikov, Andrey V.; Kireenkov, Alexander U.


    The paper presents the results of experimental investigations of the fiber optic hydrophone array consisting of six sensors, placed in one thin sensitive cable. Sensors were formed by pairs of Bragg gratings spaced 1.5 m apart and recorded in a birefringent optical fiber with the elliptical stressed coating. To form an extended sensor array the optical fiber was additionally covered with a silicone material RTV655 and protective coatings. Experimental investigations of the array showed that fiber-optic sensors pressure sensitivity increases as the acoustic frequency decreases at average value from -169.4 dB re rad/uPa at 495 Hz to -143.7 dB re rad/uPa at 40 Hz. The minimum detectable pressure was at average value from 53 mPa/√Hz at 495 Hz to 8.3 mPa/√Hz at 40 Hz. The obtained results might be used for developing and producing long thin hydroacoustic arrays for geophysical investigations and other hydroacoustic applications.

  3. Experimental investigation of nonlinear optical properties of Ag nanoparticles: Effects of size quantization (United States)

    Sato, Rodrigo; Ohnuma, Masato; Oyoshi, Keiji; Takeda, Yoshihiko


    The effects of size quantization on the nonlinear optical response of Ag nanoparticles are experimentally studied by spectroscopic ellipsometry and femtosecond spectroscopic pump-and-probe techniques. In the vicinity of a localized surface-plasmon resonance (2.0-3.5 eV), we have investigated the optical nonlinearity of Ag particles embedded in silica glass for particle diameters ranging from 3.0 to 16 nm. The intrinsic third-order optical susceptibility χm(3) of Ag particles exhibited significant spectral and size dependences. These results are explained as quantum and dielectric confinements and are compared to the results of theoretical quantum finite-size effects calculation for metallic particles. In light of these results, we discuss the contribution of interband transitions to the size dependence of χm(3). Quantum size effects lead to an increase in nonlinearity in small Ag particles.

  4. Investigating the use of the acousto-optic effect for acoustic holography

    DEFF Research Database (Denmark)

    Torras Rosell, Antoni; Fernandez Grande, Efren; Jacobsen, Finn;


    Recent studies have demonstrated that the acousto-optic effect, that is, the interaction between sound and light, can be used as a means to visualize acoustic fields in the audible frequency range. The changes of density caused by sound waves propagating in air induce phase shifts to a laser beam...... that travels through the acoustic field. This phenomenon can in practice be captured with a laser Doppler vibrometer (LDV), and the pressure distribution of the acoustic field can be reconstructed using tomography. The present work investigates the potential of the acousto-optic effect in acoustic holography....... Two different holographic methods are examined for this purpose. One method first reconstructs the hologram plane using acousto-optic tomography and then propagates it using conventional near-field acoustic holography (NAH). The other method exploits the so-called Fourier Slice Theorem and bases all...

  5. Ground-based complex for detection and investigation of fast optical transients in wide field (United States)

    Molinari, Emilio; Beskin, Grigory; Bondar, Sergey; Karpov, Sergey; Plokhotnichenko, Vladimir; de-Bur, Vjacheslav; Greco, Guiseppe; Bartolini, Corrado; Guarnieri, Adriano; Piccioni, Adalberto


    To study short stochastic optical flares of different objects (GRBs, SNs, etc) of unknown localizations as well as NEOs it is necessary to monitor large regions of sky with high time resolution. We developed a system which consists of wide-field camera (FOW is 400-600 sq.deg.) using TV-CCD with time resolution of 0.13 s to record and classify optical transients, and a fast robotic telescope aimed to perform their spectroscopic and photometric investigation just after detection. Such two telescope complex TORTOREM combining wide-field camera TORTORA and robotic telescope REM operated from May 2006 at La Silla ESO observatory. Some results of its operation, including first fast time resolution study of optical transient accompanying GRB and discovery of its fine time structure, are presented. Prospects for improving the complex efficiency are given.

  6. Investigation on optical absorption properties of ion irradiated single walled carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Vishalli,, E-mail:; Dharamvir, Keya, E-mail: [Department of Physics, Panjab University, Chandigarh (India); Kaur, Ramneek; Raina, K. K. [Materials Research Laboratory, School of Physics and Materials Science, Thapar University, Patiala (India); Avasthi, D. K. [Materials Science Group, Inter University Accelerator Centre, ArunaAsaf Ali Marg, NewDelhi (India); Jeet, Kiran [Electron Microscopy and Nanoscience laboratory, Punjab Agriculture University, Ludhiana (India)


    In the present study change in the optical absorption properties of single walled carbon nanotubes (SWCNTs) under nickel ion (60 MeV) irradiation at various fluences has been investigated. Langmuir Blodgett technique is used to deposit SWCNT thin film of uniform thickness. AFM analysis shows a network of interconnected bundles of nanotubes. UV-Vis-NIR absorption spectra indicate that the sample mainly contain SWCNTs of semiconducting nature. It has been found in absorption spectra that there is decrease in the intensity of the characteristic SWCNT peaks with increase in fluence. At fluence value 1×10{sup 14} ions/cm{sup 2} there is almost complete suppression of the characteristic SWCNTs peaks.The decrease in the optical absorption with increase in fluence is due to the increase in the disorder in the system which leads to the decrease in optically active states.

  7. Investigation of patterning effects in ultrafast SOA-based optical switches

    DEFF Research Database (Denmark)

    Xu, Jing; Zhang, Xinliang; Mørk, Jesper


    Ultrafast optical switching employing semiconductor optical amplifier (SOA) based optical switches has been demonstrated at bitrates up to 640 Gbit/s. However, patterning effects caused by relatively slow recovery processes in semiconductor structures remain as an important deteriorating factor...... that limits the ultimate speed at which SOA-based switches can be operated. In this paper, we investigate the patterning effects of SOA-based switches using a systematic approach. A simple condition for the lower bound limit of the bit pattern length that should be adopted in the performance evaluations...... of the switches is derived. It is shown that the minimum bit pattern length scales linearly with the bitrate and the recovery time of the SOA. To overcome the excessive computation time needed for numerical analysis at long pseudorandom binary sequence (PRBS) lengths, an effective method, i.e., periodic method...

  8. Theoretical Investigation of Optical WDM Network Performance in the Presence of FWM and ASE Noise (United States)

    Iyer, Sridhar; Joy, Ambily


    In this article, for an optical star wavelength division multiplexing (WDM) network, with quality factor (Q-factor) as performance metric, we investigate the performance degradation due to the combined effects of four-wave mixing (FWM) and amplified spontaneous emission (ASE) noise. A mathematical model is developed, and the simulations are performed based on the optical frequency grid defined by the ITU-T Recommendation G.692. Further, the analysis is conducted for the optical fibers that are ITU-T compliant viz. G.652, G. 652D, G. 653, G. 654 and G.655. The simulation results show that, compared to the other fiber types, performance of the G. 652D and G.652 fibers is the "best", thus justifying the preferred use of fibers with high dispersion and effective area values. The simulation results also highlight that with the use of a fiber having low dispersion and effective area value, it may not be possible to obtain the desired performance.

  9. Investigation in morphology and optical properties of electron beam gun evaporated nanostructured Bromoindium phthalocyanine thin films (United States)

    Azim-Araghi, M. E.; Sahebi, R.


    Bromoindium phthalocyanine in thin film form was prepared by electron beam gun evaporation technique, using pre-cleaned polyborosilicate glass as substrate. 2D AFM image confirms that the surface of BrInPc thin film is granular with a grain size of 40-60 nm. 3D AFM image confirms that surface is homogeneous and its RMS roughness is 4.9 nm. The UV-VIS absorption spectrum showed two well-known absorption bands of the phthalocyanines, B and Q bands and characteristics Davydov splitting were observed. The optical transition determined to be direct allowed and the value of optical band gap was obtained. The value of Urbach energy was calculated. To investigation in the effect of thermal annealing on optical properties of BrInPc thin films, we annealed some thin films at 473 and 603 K for 1 h. As the result of thermal annealing we observed another absorption peak, named N-band, in absorption spectrum. A red shift observed in the position of B-band and Q-band peaks. There was not changing in optical transition mechanism. The value of optical band gap decreased and the Urbach energy increased as the result of thermal annealing.

  10. Synthesis, structural investigation and thermal properties of a novel manganese complex Mn2(DAT)2Cl4(H2O)4 (DAT=1,5-diaminotetrazole). (United States)

    Zhang, Jian-Guo; Li, Zhi-Min; Zang, Yan; Zhang, Tong-Lai; Shu, Yuan-Jie; Yang, Li; Power, Philip P


    A novel manganese complex Mn(2)(DAT)(2)Cl(4)(H(2)O)(4), where DAT is 1,5-diaminotetrazole, was synthesized by the reaction of manganese(II) chloride tetrahydrate and 1,5-diaminotetrazole (DAT) in ethanol, and characterized by elemental analysis, FT-IR spectroscopy. The crystal structure was determined through X-ray single crystal diffraction. The molecular unit of Mn(2)(DAT)(2)Cl(4)(H(2)O)(4) has a distorted octahedral structure, containing two central manganese cations, which coordinated by a mono-dentate terminal chloride, a bulky DAT ligand and two water molecules, and linked by two bidentate bridging chloride ligands. There are two main exothermic peaks and one endothermic peak in the thermal decomposition process, investigated by differential scanning calorimetry (DSC) and thermo-gravimetric analysis (TGA), the final residue of the title compound at 600 degrees C is MnO. The kinetic parameters of the endothermic process and two main exothermic processes were studied by applying the Kissinger's and Ozawa-Doyle's methods.

  11. Optical investigations of high pressure glow discharges based on MSE arrays

    Energy Technology Data Exchange (ETDEWEB)

    Penache, C.; Hohn, O.; Schmidt-Boecking, H. [Frankfurt Univ. (Germany); Spielberger, L. [Deutsche Gesellschaft fuer Technische Zusammenarbeit GmbH (GTZ), Eschborn (Germany); Braeuning-Demian, A.; Penache, D. [Gesellschaft fuer Schwerionenforschung mbH, Darmstadt (Germany)


    The micro-structure-electrode (MSE) arrays are providing a non-thermal high pressure plasma. These arrays consist of a matrix of holes perforated in a thin multilayer made out of two metallic foils separated by a dielectric. The holes diameter and the thickness of the insulator spacer need to be around 100 {mu}m to allow for the MSE operation at pressure ranging from 0.1 to 1 bar and above. In this work single direct current microdischarges and systems of parallel operated holes in argon at 0.2 bar have been optically investigated. The spatial distribution of the emitted light has been monitored by a digital camera connected to an optical microscope. The UV photon emission has been recorded by a position sensitive photon detector allowing for space and time resolved measurements. Its time resolution of about 1 nsec makes possible the investigation of fast processes, e.g. the constriction of the discharge. Due to its typical position resolution of 100 {mu}m, this detector needs to be used in combination with an optical system allowing for the magnification of the discharge area. The optical appearance show a stable, volume filling glow discharge, fact proved also by the typical current-voltage characteristic.

  12. Investigation of Optical and Luminescence Properties of Soda Lime Borate Glasses Doped with Sm3+ Ion

    Institute of Scientific and Technical Information of China (English)

    FALAK Zaman; GUL Rooh; NATTAPON Srisittipokakun; JACKRAPONG Kaewkhao


    This paper was to investigate the optical and luminescence properties of Sm3+ doped SLB glasses by a melt quenching technique. The optical and luminescence properties of the prepared glass samples were investigatedvia ab-sorption and photoluminescence spectra, respectively. The related physical and optical parameters were also calculated. From optical absorption measurements, the transition6H5/2→6P3/2at 403 nm has a higher spectral intensity and is a hypersensitive transition. From photoluminescence spectra, four prominent emission spectra appear. The most intense band is located at4G5/2→6H9/2(599 nm), which is the characteristic emission range of Sm3+ ions with the reddish orange color. The experimental decay time of the4G5/2 level of Sm3+ SLB glasses was determined. The decay time decreases from 1.367 to 0.333 ms with increasing the content of Sm3+. The color coordinates (x,y) of the prepared glasses passes through the reddish-orange region in the CIE 1931 diagram and are suitable for orange LEDs, optoelectronics, and solid- state lighting. The further investigation on the optimization of the dopant content in the SLB glasses was suggested.

  13. Nonlinear optical switching behavior in the solid state: A theoretical investigation on anils

    KAUST Repository

    Ségerie, Audrey


    The linear (π(1)) and second-order nonlinear (π(2)) optical properties of two anil crystals, [N-(4-hydroxy)-salicylidene-amino-4-(methylbenzoate) and N-(3,5-di-tert- butylsalicylidene)-4-aminopyridine, denoted 4A and 4P, respectively], as well as the optical contrasts upon switching between their enol (E) and keto (K) forms, have been investigated by combining the molecular responses calculated using quantum chemistry methods and an electrostatic interaction scheme to account for the local field effects. It is found that intermolecular interactions impact differently the K/E optical contrasts in the two systems, which illustrates the importance of the supramolecular organization on the macroscopic responses. In 4A, the surrounding effects on the (hyper)polarizabilities are similar in the enol and keto forms, leading to optical contrasts very close to those of the isolated molecule. In contrast, an enhancement of the second-order susceptibility is observed in the keto form of 4P, leading to a large π(2)(K)/π(2)(E) contrast. Moreover, the π(2)(4A)/π(2)(4P) ratio for the most stable enol forms is obtained to be in good agreement with previous experimental investigations, which supports the reliability of the computational procedure. © 2011 American Chemical Society.

  14. Investigation on the mechanism and applications of the reaction Cl2+2HBr=2HCl+Br2

    Institute of Scientific and Technical Information of China (English)

    肖鹤鸣; 王遵尧; 肖继军; 陈兆旭


    The mechanism of reaction CI2+2HBr=2HCI+Br2 has been carefully investigated with density functional theory (DFT) at B3LYP/6-311G** level. A series of three-centred and four-centred transition states have been obtained. The activation energy (138.96 and 147.24 kJ/mol, respectively) of two bimolecular elementary reactions CI2+HBr→HCI+BrCI and BrCI+HBr→HCI+Br2 is smaller than the dissociation energy of CI2, HBr and BrCI, indicating that it is favorable for the title reaction occurring in the bimolecular form. The reaction has been applied to the chemical engineering process of recycling Br2 from HBr. Gaseous CI2 directly reacts with HBr gas, which produces gaseous mixtures containing Br2, and liquid Br2 and HCI are obtained by cooling the mixtures and further separated by absorption with CCI4. The recovery percentage of Br2 is more than 96%, and the CI2 remaining in liquid Br2 is less than 3.0%. The paper provides a good example of solving the difficult problem in chemical engineering with basic theory.

  15. An investigation of the influence of residual amplitude modulation in phase electro-optic modulator on the signal of fiber-optic gyroscope (United States)

    Pogorelaya, D. A.; Smolovik, M. A.; Strigalev, V. E.; Aleynik, A. S.; Deyneka, I. G.


    The investigation is devoted to residual amplitude modulation (RAM) of phase electro-optic modulator, which guides are made in LiNbO3 crystal by Ti diffusion technology. An analysis is presented that shows influence of RAM on the signal of fiber-optic gyroscope. The RAM compensation method is offered.

  16. Investigation progress on key photonic integration for application in optical communication network

    Institute of Scientific and Technical Information of China (English)



    Proceeding from the consideration of the demands from the functional architecture of high speed, high capacity optical communication network, this paper points out that photonic integrated devices, including high speed response laser source, narrow band response photodetector high speed wavelength converter, dense wavelength multi/demultiplexer, low loss high speed response photo-switch and multi-beam coupler are the key components in the system. The investigation progress in the laboratory will be introduced.

  17. Experimental investigation of local properties and statistics of optical vortices in random wave fields

    DEFF Research Database (Denmark)

    Wang, W.; Hanson, Steen Grüner; Miyamoto, Y.;


    We present the first direct experimental evidence of the local properties of optical vortices in a random laser speckle field. We have observed the Berry anisotropy ellipse describing the anisotropic squeezing of phase lines close to vortex cores and quantitatively verified the Dennis angular...... momentum rule for its phase. Some statistics associated with vortices, such as density, anisotropy ellipse eccentricity, and its relation to zero crossings of real and imaginary parts of the random field, are also investigated by experiments....

  18. Investigation of Optical Nonlinearities in Bi-Doped Se-Te Chalcogenide Thin Films (United States)

    Yadav, Preeti; Sharma, Ambika


    The present paper reports the nonlinear optical properties of chalcogenide Se85- x Te15Bi x (0 ≤ x ≤ 5) thin films. The formulation proposed by Boling, Fournier, and Snitzer and Tichy and Ticha has been used to compute the nonlinear refractive index n 2. The two-photon absorption coefficient β 2, and first- and third-order susceptibilities [ χ (1) and χ (3)] are also reported. The nonlinear refractive index n 2 is well correlated with the linear refractive index n and Wemple-DiDomenico (WDD) parameters, in turn depending on the density ρ and molar volume V m of the system. The density of the system is calculated experimentally by using Archimedes' principle. The linear optical parameters, viz. n, WDD parameters, and optical bandgap E g, are measured experimentally using ellipsometric curves obtained by spectrophotometry. The composition-dependent behavior of n 2 is analyzed on the basis of various parameters, viz. density, bond distribution, cohesive energy (CE), and optical bandgap E g, of the system. The variation of n 2 and β 2 with changing bandgap E g is also reported. The values of n 2 and χ (3) of the investigated chalcogenides are compared with those of pure silica, oxide, and other Se-based glasses.

  19. Separation of CsCl and SrCl2 from a ternary CsCl-SrCl2-LiCl via a zone refining process for waste salt minimization of pyroprocessing (United States)

    Shim, Moonsoo; Choi, Ho Gil; Yi, Kyung Woo; Hwang, Il Soon; Lee, Jong Hyeon


    The purification of LiCl salt mixture has traditionally been carried out by a melt crystallization process. To improve the throughput of zone refining, three heaters were installed in the zone refiner. The zone refining method was used to grow pure LiCl salt ingots from LiCl-CsCl-SrCl2 salt mixture. The main investigated parameters were the heater speed and the number of passes. A change in the LiCl crystal grain size was observed according to the horizontal direction. From each zone refined salt ingot, samples were collected horizontally. To analyze the concentrations of Sr and Cs, an inductively coupled plasma optical emission spectrometer and inductively coupled plasma mass spectrometer were used, respectively. The experimental results show that Sr and Cs concentrations at the initial region of the ingot were low and reached their peak at the final freezing region of the salt ingot. Concentration results of zone refined salt were compared with theoretical results yielded by the proposed model to validate its predictions. The keff of Sr and Cs were 0.13 and 0.11, respectively. The decontamination factors of Sr and Cs were 450 and 1650, respectively.

  20. Differential cerebro spinal fluid proteome investigation of Leber hereditary optic neuropathy (LHON) and multiple sclerosis. (United States)

    D'Aguanno, Simona; Barassi, Alessandra; Lupisella, Santina; d'eril, Gianlodovico Melzi; Del Boccio, Piero; Pieragostino, Damiana; Pallotti, Francesco; Carelli, Valerio; Valentino, Maria Lucia; Liguori, Rocco; Avoni, Patrizia; Bernardini, Sergio; Gambi, Domenico; Urbani, Andrea; Federici, Giorgio


    Leber's hereditary optic neuropathy (LHON) is a genetic disease leading to the loss of central vision and optic nerve atrophy. The existence of occasional cases of LHON patients developing a Multiple Sclerosis (MS)-like illness and the hypothesis that mtDNA variants may be involved in MS suggest the possibility of some common molecular mechanisms linking the two diseases. We have pursued a comparative proteomics approach on cerebrospinal fluid (CSF) samples from LHON and MS patients, as well as healthy donors by employing 2-DE gel separations coupled to MALDI-TOF-MS and nLC-MS/MS investigations. 7 protein spots showed significant differential distribution among the three groups. Both CSF of LHON or MS patients are characterized by lower level of transthyretin dimer adduct while a specific up regulation of Apo A-IV was detected in LHON CSF.

  1. Investigations of electrical and optical properties of functional TCO thin films

    Directory of Open Access Journals (Sweden)

    Domaradzki Jarosław


    Full Text Available Transparent conducting oxide (TCO films of indium-tin-oxide were evaporated on the surface of silicon wafers after phosphorous diffusion and on the reference glass substrates. The influence of deposition process parameters (electron beam current, oxygen flow and the substrate temperature on optical and electrical properties of evaporated thin films were investigated by means of resistivity measurements and optical spectrophotometry. The performance of prepared thin films was judged by calculated figure of merit and the best result was obtained for the sample deposited on the substrate heated to the 100 °C and then removed from the deposition chamber and annealed in an air for 5 minutes at 400 °C. Refractive index and extinction coefficient were evaluated based on measured transmission spectra and used for designing of antireflection coating for solar cell. The obtained results showed that prepared TCO thin films are promising as a part of counter electrode in crystalline silicon solar cell construction.

  2. Um exercício rigoroso de investigação clínica A rigorous exercise on clinical investigation

    Directory of Open Access Journals (Sweden)

    Angélica Bastos


    Full Text Available O artigo visa extrair da produção psicanalítica de Juan Carlos Cosentino as coordenadas de sua investigação. Com base no procedimento segundo o qual Freud concebeu a elaboração do saber em psicanálise, busca-se delimitar suas questões clínicas. Nas fobias, na angústia e nos sonhos, o psicanalista distingue duas ordens de laço na experiência analítica: por um lado, a fantasia e a neurose de transferência, e, por outro, a estrutura. Procura-se demonstrar o quanto sua releitura de Freud é movida por problemáticas originais, configurando uma pesquisa rigorosa impulsionada pela direção do tratamento e ditada pela função do desejo do analista.The article aims at drawing out the coordinates of investigation from the psychoanalytical production of Juan Carlos Cosentino. Based on the proceedings which Freud conceived knowledge elaboration in psychoanalysis, the clinical questions are delimited in his investigation. The psychoanalyst distinguishes two bond types in the analytical experience in relation to phobias, angst and dreams: on one hand, fantasy and transfer neurosis and on the other hand, the structure. We try to demonstrate how much his reading on Freud is powered by original problems, thus outlining a rigorous research triggered by the treatment course and ruled by the function of the therapist's desire.

  3. Microscopic investigations of the terahertz and the extreme nonlinear optical response of semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Golde, Daniel


    In the major part of this Thesis, we discuss the linear THz response of semiconductor nanostructures based on a microscopic theory. Here, two different problems are investigated: intersubband transitions in optically excited quantum wells and the THz plasma response of two-dimensional systems. In the latter case, we analyze the response of correlated electron and electron-hole plasmas. Extracting the plasma frequency from the linear response, we find significant deviations from the commonly accepted two-dimensional plasma frequency. Besides analyzing the pure plasma response, we also consider an intermediate regime where the response of the electron-hole plasma consists of a mixture of plasma contributions and excitonic transitions. A quantitative experiment-theory comparison provides novel insights into the behavior of the system at the transition from one regime to the other. The discussion of the intersubband transitions mainly focuses on the coherent superposition of the responses from true THz transitions and the ponderomotively accelerated carriers. We present a simple method to directly identify ponderomotive effects in the linear THz response. Apart from that, the excitonic contributions to intersubband transitions are investigated. The last part of the present Thesis deals with a completely different regime. Here, the extreme nonlinear optical response of low-dimensional semiconductor structures is discussed. Formally, extreme nonlinear optics describes the regime of light-matter interaction where the exciting field is strong enough such that the Rabi frequency is comparable to or larger than the characteristic transition frequency of the investigated system. Here, the Rabi frequency is given by the product of the electrical field strength and the dipole-matrix element of the respective transition. Theoretical investigations have predicted a large number of novel nonlinear effects arising for such strong excitations. Some of them have been observed in

  4. Optical investigations of combustion process in SI and CI engines fuelled with butanol blends

    Energy Technology Data Exchange (ETDEWEB)

    Marchitto, L.; Mazzei, A.; Merola, S.S.; Tornatore, C. [CNR Napoli, Naples (Italy). Istituto Motori; Valentino, G.


    The use of alternative fuels, as biodiesel and ethanol, for light duty engines to approach the target of low exhaust emissions without fuel economy and performance penalty has been widely investigated. Recently it is growing the interest in the butanol and bio-butanol as viable alternatives either single or blended with conventional based fuels. In this paper, butanol effects on combustion processes were investigated through conventional methods and optical diagnostics applied in the combustion chamber of a compression ignition engine and of a spark ignition engine. Blends of diesel and n-butanol were used in a common rail DI diesel engine running at different operating conditions. Fuel injection timing and oxygen at the intake were changed in a single cylinder compression ignition engine equipped with common rail multi-jets injection system. Spray combustion and pollutant formation were investigated though UV-visible digital imaging and natural emission spectroscopy. Flame emissions and spectroscopy were applied in an optically accessible cylinder of a port fuel-injection, spark-ignition engine with an external boosting device. The engine worked with a stoichiometric mixture at medium speed and boosting in wide open throttle condition. Normal and knocking combustion was tested. Experiments in both the engines demonstrated that butanol allowed to reduce carbonaceous compounds formation and soot emission and to decrease unpleasant effects related to the combustion process such as the fuel deposition burning. Moreover some emission bands of OH radicals could be used as feature of different phenomena related to the combustion process. (orig.)

  5. Direct composite fillings: an optical coherence tomography and microCT investigation (United States)

    Negrutiu, Meda L.; Sinescu, Cosmin; Borlea, Mugurel V.; Manescu, Adrian; Duma, Virgil F.; Rominu, Mihai; Podoleanu, Adrian G.


    The treatment of carious lesions requires removal of affected dental tissue thus creating cavities that are to be filled with dedicated materials. There are several methods known which are used to assess the quality of direct dental restorations, but most of them are invasive. Optical tomographic techniques are of particular importance in the medical imaging field, because these techniques can provide non-invasive diagnostic images. Using an en-face version of OCT, we have recently demonstrated real time thorough evaluation of quality of dental fillings. The major aim of this study was to analyses the optical performance of adhesives modified with zirconia particles in different concentrations in order to improve the contrast of OCT imaging of the interface between the tooth structure, adhesive and composite resin. The OCT investigations were validated by micro CT using synchrotron radiation. The OCT Swept Source is a valuable investigation tool for the clinical evaluation of class II direct composite restorations. The unmodified adhesive layer shows poor contrast on regular OCT investigations. Adding zirconia particles to the adhesive layer provides a better scattering which allows a better characterization and quantification of direct restorations.

  6. Four new chalcohalides, NaBa{sub 2}SnS{sub 4}Cl, KBa{sub 2}SnS{sub 4}Cl, KBa{sub 2}SnS{sub 4}Br and CsBa{sub 2}SnS{sub 4}Cl: Syntheses, crystal structures and optical properties

    Energy Technology Data Exchange (ETDEWEB)

    Li, Chao; Feng, Kai; Tu, Heng [Center for Crystal Research and Development, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Key Laboratory of Functional Crystals and Laser Technology, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); University of the Chinese Academy of Sciences, Beijing 100049 (China); Yao, Jiyong, E-mail: [Center for Crystal Research and Development, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Key Laboratory of Functional Crystals and Laser Technology, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Wu, Yicheng [Center for Crystal Research and Development, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Key Laboratory of Functional Crystals and Laser Technology, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China)


    Four new chalcohalides, namely NaBa{sub 2}SnS{sub 4}Cl, KBa{sub 2}SnS{sub 4}Cl, KBa{sub 2}SnS{sub 4}Br, and CsBa{sub 2}SnS{sub 4}Cl, have been synthesized by the conventional high temperature solid-state reactions. They crystallize in three different space groups: space group I4/mcm for NaBa{sub 2}SnS{sub 4}Cl and KBa{sub 2}SnS{sub 4}Cl, Pnma for KBa{sub 2}SnS{sub 4}Br, and P2{sub 1}/c for CsBa{sub 2}SnS{sub 4}Cl. In all four compounds, the X{sup −} halide anions are only connected to six alkali metal or Ba cations, and the Sn atoms are only tetrahedrally enjoined to four S atoms. However, the M–X–Ba pseudo layers and the SnS{sub 4} tetrahedra are arranged in different ways in the three structural types, which demonstrates the interesting effect of ionic radii on the crystal structures. UV–vis–NIR spectroscopy measurements indicate that NaBa{sub 2}SnS{sub 4}Cl, KBa{sub 2}SnS{sub 4}Cl, KBa{sub 2}SnS{sub 4}Br, and CsBa{sub 2}SnS{sub 4}Cl have band gaps of 2.28, 2.30, 1.95, and 2.06 eV, respectively. - Graphical abstract: A new series of chalcohalides, NaBa{sub 2}SnS{sub 4}Cl, KBa{sub 2}SnS{sub 4}Cl, KBa{sub 2}SnS{sub 4}Br and CsBa{sub 2}SnS{sub 4}Cl have been obtained. They present three different space groups: NaBa{sub 2}SnS{sub 4}Cl and KBa{sub 2}SnS{sub 4}Cl in space group I4/mcm, KBa{sub 2}SnS{sub 4}Br in Pnma and CsBa{sub 2}SnS{sub 4}Cl in space group P2{sub 1}/c. UV–vis–NIR spectroscopy measurements indicate that NaBa{sub 2}SnS{sub 4}Cl, KBa{sub 2}SnS{sub 4}Cl, KBa{sub 2}SnS{sub 4}Br and CsBa{sub 2}SnS{sub 4}Cl have band gaps of 2.28, 2.30 1.95, and 2.06 eV, respectively. - Highlights: • Four new chalcohalides, NaBa{sub 2}SnS{sub 4}Cl, KBa{sub 2}SnS{sub 4}Cl, KBa{sub 2}SnS{sub 4}Br and CsBa{sub 2}SnS{sub 4}Cl were obtained. • They adopt three different structures owing to different ionic radii and elemental electronegativity. • NaBa{sub 2}SnS{sub 4}Cl, KBa{sub 2}SnS{sub 4}Cl, KBa{sub 2}SnS{sub 4}Br and CsBa{sub 2}SnS{sub 4}Cl have band gaps

  7. Molecular structure, optical and magnetic properties of metal-free phthalocyanine radical anions in crystalline salts (H2Pc˙-)(cryptand[2,2,2][Na(+)])·1.5C6H4Cl2 and (H2Pc˙-)(TOA+)·C6H4Cl2 (TOA+ is tetraoctylammonium cation). (United States)

    Konarev, Dmitri V; Zorina, Leokadiya V; Khasanov, Salavat S; Litvinov, Aleksey L; Otsuka, Akihiro; Yamochi, Hideki; Saito, Gunzi; Lyubovskaya, Rimma N


    Ionic compounds containing radical anions of metal-free phthalocyanine (H2Pc˙(-)): (H2Pc˙(-))(cryptand[2,2,2][Na(+)])·1.5C6H4Cl2 (1) and (H2Pc˙(-))(TOA(+))·C6H4Cl2 (2) have been obtained as single crystals for the first time. Their crystal structures have been determined, and optical and magnetic properties have been investigated. The H2Pc˙(-) radical anions have a slightly bowl-like shape with four pyrrole nitrogen atoms located below the molecular plane, while four phenylene substituents are located above this plane. Changes in the average length of N-C and C-C bonds in H2Pc˙(-) in comparison with those in neutral H2Pc indicate that negative charge is mainly delocalized over the 24-atom phthalocyanine ring rather than the phenylene substituents. The H2Pc˙(-) formation is accompanied by a shift of up to 10 cm(-1) and disappearance of some intense IR-active bands whereas the band of the N-H stretching mode is shifted by 21-27 cm(-1) to larger wavenumbers. New bands attributed to H2Pc˙(-) appear in the NIR spectra of the salts with maxima at 1033 and 1028 nm for 1 and 2, respectively. The formation of H2Pc˙(-) is accompanied by the splitting of the Soret and Q-bands of H2Pc into several bands and their blue-shift up to 32 nm. Narrow EPR signals with g = 2.0033 and linewidth of 0.16-0.24 mT at room temperature in the spectra of the salts were attributed to the H2Pc˙(-) radical anions. According to SQUID measurements they have S = 1/2 spin states with effective magnetic moments of 1.73 (1) and 1.78 (2) μB at 300 K. Magnetic behavior of 1 and 2 follows the Curie-Weiss law with negative Weiss temperatures of -0.9 and -0.5 K, respectively, indicating weak antiferromagnetic interactions of spins. The EPR signal splits into two lines below 120 and 80 K for 1 and 2, respectively and these lines are noticeably broadened below 25 K.

  8. Investigation of optical properties of multilayer dielectric structures using prism-coupling technique

    Energy Technology Data Exchange (ETDEWEB)

    Sokolov, V I; Glebov, V N; Malyutin, A M; Molchanova, S I; Khaydukov, E V; Panchenko, V Ya [Institute on Laser and Information Technologies, Russian Academy of Sciences, Shatura, Moscow Region (Russian Federation)


    A method based on resonant excitation of waveguide modes with a prism coupler is proposed for measuring the thickness and refractive index of thin-film layers in multilayer dielectric structures. The peculiarities of reflection of TE- and TM-polarised light beams from a structure comprising eleven alternating layers of zinc sulfide (ZnS) and magnesium barium fluoride (MgBaF{sub 4}), whose thicknesses are much less than the wavelength of light, are investigated. Using the mathematical model developed, we have calculated the coefficients of reflection of collimated TE and TM light beams from a multilayer structure and determined the optical constants and thicknesses of the structure layers. The refractive indices of the layers, obtained for TE and TM polarisation of incident light, are in good agreement. The thicknesses of ZnS and MgBaF{sub 4} layers, found for different polarisations, coincide with an accuracy of ±1%. Thus, we have demonstrated for the first time that the prism-coupling technique allows one to determine the optical properties of thin-film structures when the number of layers in the structure exceeds ten layers. (integrated optics)

  9. Theoretical investigation on nonlinear optical effects in laser trapping of dielectric nanoparticles with ultrafast pulsed excitation. (United States)

    Devi, Anita; De, Arijit K


    The use of low-power high-repetition-rate ultrafast pulsed excitation in stable optical trapping of dielectric nanoparticles has been demonstrated in the recent past; the high peak power of each pulse leads to instantaneous trapping of a nanoparticle with fast inertial response and the high repetition-rate ensures repetitive trapping by successive pulses However, with such high peak power pulsed excitation under a tight focusing condition, nonlinear optical effects on trapping efficiency also become significant and cannot be ignored. Thus, in addition to the above mentioned repetitive instantaneous trapping, trapping efficiency under pulsed excitation is also influenced by the optical Kerr effect, which we theoretically investigate here. Using dipole approximation we show that with an increase in laser power the radial component of the trapping potential becomes progressively more stable but the axial component is dramatically modulated due to increased Kerr nonlinearity. We justify that the relevant parameter to quantify the trapping efficiency is not the absolute depth of the highly asymmetric axial trapping potential but the height of the potential barrier along the beam propagation direction. We also discuss the optimal excitation parameters leading to the most stable dipole trap. Our results show excellent agreement with previous experiments.

  10. Experimental and theoretical investigation of relative optical band gaps in graphene generations (United States)

    Bhatnagar, Deepika; Singh, Sukhbir; Yadav, Sriniwas; Kumar, Ashok; Kaur, Inderpreet


    Size and chemical functionalization dependant optical band gaps in graphene family nanomaterials were investigated by experimental and theoretical study using Tauc plot and density functional theory (DFT). We have synthesized graphene oxide through a modified Hummer’s method using graphene nanoplatelets and sequentially graphene quantum dots through hydrothermal reduction. The experimental results indicate that the optical band gap in graphene generations was altered by reducing the size of graphene sheets and attachment of chemical functionalities like epoxy, hydroxyl and carboxyl groups plays a crucial role in varying optical band gaps. It is further confirmed by DFT calculations that the π orbitals were more dominatingly participating in transitions shown by projected density of states and the molecular energy spectrum represented the effect of attached functional groups along with discreteness in energy levels. Theoretical results were found to be in good agreement with experimental results. All of the above different variants of graphene can be used in native or modified form for sensor design and optoelectronic applications.

  11. An investigation of doubly-resonant optical parametric oscillators and nonlinear crystals for squeezing

    Energy Technology Data Exchange (ETDEWEB)

    Stefszky, Michael; Buchler, Ben C; Symul, Thomas; Lam, Ping Koy [Quantum Optics Group, Department of Quantum Science, The Australian National University, ACT 0200 (Australia); Mow-Lowry, Conor M; McKenzie, Kirk; Chua, Sheon; McClelland, David E, E-mail: [Centre for Gravitational Physics, Department of Quantum Science, The Australian National University, ACT 0200 (Australia)


    A squeezed light source requires properties such as high squeezing amplitude, high bandwidth and stability over time, ideally using as few resources, such as laser power, as possible. We compare three nonlinear materials, two of which have not been well characterized for squeezed state production, and also investigate the viability of doubly-resonant optical parametric oscillator cavities in achieving these requirements. A model is produced that provides a new way of looking at the construction of an optical parametric oscillator/optical parametric amplifier setup where second harmonic power is treated as a limited resource. The well-characterized periodically poled potassium titanyl phosphate (PPKTP) is compared in an essentially identical setup to two relatively new materials, periodically poled stoichiometric lithium tantalate (PPSLT) and 1.7% magnesium oxide doped periodically poled stoichiometric lithium niobate (PPSLN). Although from the literature PPSLT and PPSLN present advantages such as a higher damage threshold and a higher nonlinearity, respectively, PPKTP was still found to have the most desirable properties. With PPKTP, 5.8 dB of squeezing below the shot noise limit was achieved. With PPSLT, 5.0 dB of squeezing was observed but the power required to see this squeezing was much higher than expected. A technical problem with the PPSLN limited the observed squeezing to around 1.0 dB. This problem is discussed.

  12. Optical Emission Spectroscopy Investigation of a Surface Dielectric Barrier Discharge Plasma Aerodynamic Actuator

    Institute of Scientific and Technical Information of China (English)

    LI Ying-Hong; WU Yun; JIA Min; ZHOU Zhang-Wen; GUO Zhi-Gang; PU Yi-Kang


    The optical emission spectroscopy of a surface dielectric barrier discharge plasma aerodynamic actuator is investigated with different electrode configurations, applied voltages and driving frequencies. The rotational temperature of N2 (C3IIu) molecule is calculated according to its rotational emission band near 380.5 nm. The average electron energy of the discharge is evaluated by emission intensity ratio of first negative system to second positive system of N2. The rotational temperature is sensitive to the inner space of an electrode pair. The average electron energy shows insensitivity to the applied voltage, the driving frequency and the electrode configuration.

  13. Numerical Investigation of Surface Plasmons Associated Subwavelength Optical Single-Pass Effect

    Institute of Scientific and Technical Information of China (English)

    MIN Chang-Jun; WANG Pei; JIAO Xiao-Jin; MING Hai


    Surface plasmons (SPs) associated optical single-pass effect has been investigated in novel subwavelength metallic structures, including single slit and grating structures. With influence of SPs, these metallic structures can enhance transmission in incident direction and suppress it in the opposite direction, exhibiting a single-pass effect. The finite difference time domain method is employed to study the influences of structure parameters on far-field transmission, near-field electric field distribution and extinction ratio of the single-pass transmission effect. A maximal extinction ratio of 47.83 dB is achieved in the grating structure.

  14. Simulation Investigation on Optical and Electrical Properties of Carbon Nanotube in Terahertz Region

    Institute of Scientific and Technical Information of China (English)

    HE Xiao-Yong; FU Xiao-Nan


    Under the framework of Maxwell-Garnett (M-G) model, the optical and electrical properties of singlewalled carbon naotube (SWCNT), double-walled carbon nanotube (DWCNT) and hydrogen-doped carbon nanotube (H-doped CNT) in terahertz (THz) region have been investigated. It has been found that as frequency increases the loss tangent and conductivity show a peak. The loss tangent and conductivity of SWCNT is larger than that of DWCNT and H-doped CNT. The loss tangent and conductivity increase with the increases of falling factor and the decreases of geometrical factor.

  15. Investigation of an optical method for determining the average radius of curvature of micro-optical lenticular lens arrays

    DEFF Research Database (Denmark)

    Iversen, Theis Faber Quist; Hanson, Steen Grüner; Kirkegaard, Peter


    Micro-optical elements are of great importance in areas of optoelectronics and information processing. Establishing fast, reliable methods for characterization and quality control of these elements is important in order to maintain the optical performance in a high volume production process. We i...

  16. Thermoluminescence and F centers of manganese doped NaCl and NaCl-CKl crystals exposed to gamma radiation

    Energy Technology Data Exchange (ETDEWEB)

    Somera, L.; Cruz Z, E.; Roman L, J. [UNAM, Instituto de Ciencias Nucleares, Circuito Exterior, Ciudad Universitaria, 04510 Mexico D. F. (Mexico); Hernandez A, J. M.; Murrieta S, H., E-mail: [UNAM, Instituto de Fisica, Circuito Exterior, Ciudad Universitaria, 04510 Mexico D. F. (Mexico)


    Alkali halides crystals doped with rare earths or transition metals have been widely studied due to the luminescence properties. In particular, NaCl and KCl single crystals present thermally stimulated luminescence (Tl) after gamma irradiation. The NaCl and the NaCl KCl mixed crystal doped with manganese (MnCl{sub 2}) impurity were grown by using the Czochralski method. The emission characteristic of Mn{sup 2+} was observed at 543 nm. The crystals were exposed between 0.02 and 10 kGy gamma dose from {sup 60}Co irradiator. Optical absorption at room temperature shows the peaked band at 452 nm corresponding to the manganese impurity. The F bands, was ascribed to the electron trapped in the anion vacancy in the lattice, were obtained at 452 nm and 455 nm belonging to NaCl:Mn and NaCl KCl:Mn, respectively. The F band increases as the doses increase and it was bleaching by the UV light at 470 nm. The glow curves of the samples show the first glow peak between 92-103 degrees C, while the second main peak was observed at 183 degrees C for the undoped NaCl and at 148 and 165 degrees C for the NaCl:Mn and NaCl-KCl:Mn, respectively. The main peak was slowly bleaching when the irradiated sample was illuminated with F (470 nm) light. Optical bleaching confirms that the F center has an important participation in the thermoluminescent response. The glow curves structure from the thermal bleaching suggests the participation of different kind of traps. Also, the kinetics parameters such as activation energy (E), frequency factor (s) and the kinetic order (b) were investigated. (Author)

  17. Oscillating optical tweezer-based 3-D confocal microrheometer for investigating the intracellular micromechanics and structures (United States)

    Ou-Yang, H. D.; Rickter, E. A.; Pu, C.; Latinovic, O.; Kumar, A.; Mengistu, M.; Lowe-Krentz, L.; Chien, S.


    Mechanical properties of living biological cells are important for cells to maintain their shapes, support mechanical stresses and move through tissue matrix. The use of optical tweezers to measure micromechanical properties of cells has recently made significant progresses. This paper presents a new approach, the oscillating optical tweezer cytorheometer (OOTC), which takes advantage of the coherent detection of harmonically modulated particle motions by a lock-in amplifier to increase sensitivity, temporal resolution and simplicity. We demonstrate that OOTC can measure the dynamic mechanical modulus in the frequency range of 0.1-6,000 Hz at a rate as fast as 1 data point per second with submicron spatial resolution. More importantly, OOTC is capable of distinguishing the intrinsic non-random temporal variations from random fluctuations due to Brownian motion; this capability, not achievable by conventional approaches, is particular useful because living systems are highly dynamic and often exhibit non-thermal, rhythmic behavior in a broad time scale from a fraction of a second to hours or days. Although OOTC is effective in measuring the intracellular micromechanical properties, unless we can visualize the cytoskeleton in situ, the mechanical property data would only be as informative as that of "Blind men and the Elephant". To solve this problem, we take two steps, the first, to use of fluorescent imaging to identify the granular structures trapped by optical tweezers, and second, to integrate OOTC with 3-D confocal microscopy so we can take simultaneous, in situ measurements of the micromechanics and intracellular structure in living cells. In this paper, we discuss examples of applying the oscillating tweezer-based cytorheometer for investigating cultured bovine endothelial cells, the identification of caveolae as some of the granular structures in the cell as well as our approach to integrate optical tweezers with a spinning disk confocal microscope.

  18. Investigation of radiative effects of the optically thick dust layer over the Indian tropical region

    Energy Technology Data Exchange (ETDEWEB)

    Das, S.K.; Chen, J.P. [National Taiwan Univ. (China). Dept. of Atmospheric Sciences; Ratnam, M. Venkat; Jayaraman, A. [National Atmospheric Research Laboratory, Tirupati (India)


    Optical and physical properties of aerosols derived from multi-satellite observations (MODIS-Aqua, OMI-Aura, MISR-Terra, CALIOP-CALIPSO) have been used to estimate radiative effects of the dust layer over southern India. The vertical distribution of aerosol radiative forcing and heating rates are calculated with 100m resolution in the lower atmosphere, using temperature and relative humidity data from balloon-borne radiosonde observations. The present study investigates the optically thick dust layer of optical thickness 0.18 {+-} 0.06 at an altitude of 2.5 {+-} 0.7 km over Gadanki, transported from the Thar Desert, producing radiative forcing and heating rate of 11.5 {+-} 3.3 W m{sup -2} and 0.6 {+-} 0.26 K day{sup -1}, respectively, with a forcing efficiency of 43 W m{sup -2} and an effective heating rate of 4Kday-1 per unit dust optical depth. Presence of the dust layer increases radiative forcing by 60% and heating rate by 60 times at that altitude compared to nondusty cloud-free days. Calculation shows that the radiative effects of the dust layer strongly depend on the boundary layer aerosol type and mass loading. An increase of 25% of heating by the dust layer is found over relatively cleaner regions than urban regions in southern India and further 15% of heating increases over the marine region. Such heating differences in free troposphere may have significant consequences in the atmospheric circulation and hydrological cycle over the tropical Indian region. (orig.)

  19. Investigating the impact of NaCl salinity on growth, β-carotene, and chlorophyll a in the content life of halophytes of algae Chlorella sp.

    Directory of Open Access Journals (Sweden)

    Mojtaba Fathi


    Full Text Available Algae are used for many purposes as: food industry, animal feeding, soil enrichment andbiodiesel production. Chlorella is widely cultivated from microalgae species as it is rich in nutrients andhas its implementation as a healthy food use. In this study, the impact of NaCl salinity on growth, betacarotene,and chlorophyll a of Chlorella sp. has been investigated. This study results in three salinities(10, 30, 50 g L-1, respectively have shown that 30 g L-1 concentration has the highest value of cellnumber in day 15th and there was no significant difference between salinities on day 15th (p>0.05. Βetacaroteneresult has shown 50 g L-1 salinity and the highest value of beta-carotene did not indicate anystatistically significant differences between treatments (p>0.05. Chlorophyll a result has shown highestvalue in all treatments (it was in 50 g L-1. However, there was no significant difference betweensalinities on day 5th (p>0.05.

  20. A novel electro-optical pump-probe system for bioelectromagnetic investigations (United States)

    De Angelis, Annalisa; Couderc, Vincent; Leproux, Philippe; Labruyère, Alexis; Tonello, Alessandro; El Amari, Saad; Arnaud-Cormos, Delia; Leveque, Philippe


    In the area of bioelectromagnetic studies there is a growing interest to understand the mechanisms leading to nanosecond electric fields induced electroporation. Real-time imaging techniques at molecular level could probably bring further advances on how electric fields interact with living cells. However the investigations are limited by the present-day lack of these kinds of advanced instrumentations. In this context, we present an innovative electro-optical pump-probe system. The aim of our project is to provide a performing and compact device for electrical stimulation and multiplex Coherent anti-Stokes Raman Scattering (M-CARS) imaging of biological cells at once. The system consists of a 1064 nm sub-nanosecond laser source providing both a monochromatic pump and a polychromatic Stokes optical beam used in a CARS process, as well as the trigger beam for the optoelectronic switching-based electrical pulse generator. The polychromatic Stokes beam (from 600 to 1700 nm) results from a supercontinuum generation in a photonic crystal fiber (PCF). A detailed spectro-temporal characterization of such a broadband spectrum shows the impact of the nonlinear propagation in the fiber on the Stokes wave. Despite the temporal distortions observable on Stokes pulse profiles, their spectral synchronization with the pump pulse remains possible and efficient in the interesting region between 1100 nm and 1700 nm. The electrical stimulation device consists of a customized generator combining microstrip-line technology and laser-triggered photoconductive semiconductor switches. Our experimental characterization highlights the capability for such a generator to control the main pulse parameters (profile, amplitude and duration) and to be easily synchronized with the imaging system. We finally test and calibrate the system by means of a KDP crystal. The preliminary results suggest that this electro-optical system provides a suitable tool for real-time investigation of

  1. Exciton-thermal analysis of nonisothermal nucleation in solid solution of CuCl in glass (United States)

    Leiman, V. I.; Ashkalunin, A. L.; Derkacheva, O. Yu.; Maksimov, V. M.


    The work presents results of investigation of nucleation of CuCl nanocrystals in glass by method of exiton-thermal analysis (ETA) which is based on measuring the optical absorbance of CuCl phase in sample under heating up to the melting temperature of CuCl nanocrystals. The melting temperature of nanoparticle depends on its radius. Therefore analysis of curve of melting CuCl phase allows to determine distribution curve of nanoparticles on their radii. By the method of ETA the features of variation of CuCl nanoparticles distributions in glass when changing regime of sample annealing (nonisothermal nucleation) were studied. For example, by reducing the heating rate of the sample the concentration of particles of CuCl phase increases considerably while reducing average radius.

  2. Ge Nanoislands Grown by Radio Frequency Magnetron Sputtering: Comprehensive Investigation of Surface Morphology and Optical Properties

    Directory of Open Access Journals (Sweden)

    Alireza Samavati


    Full Text Available The comprehensive investigation of the effect of growth parameters on structural and optical properties of Si-based single layer Ge nanoislands grown via Stranski-Krastanov mechanism employing radio frequency magnetron sputtering due to its high deposition rate, easy procedure, economical cost, and safety is carried out. The estimated width and height of Ge nanoislands produced by this technique are in the range of ∼8 to ∼30 and ∼2 to 8 nm, respectively. Varieties parameters are manipulated to optimize the surface morphology and structural and optical behavior of Ge nanoislands. The resulted nanoislands are analyzed using various analytical techniques including atomic force microscope, X-ray diffraction, energy dispersive X-ray spectroscopy, room temperature photoluminescence, and Raman spectroscopy. The optimum parameters for growing high quality samples having high number density and homogenous and small size distribution are found to be 400°C for substrate temperature, 300 sec for deposition time, 10 sccm for Ar flow, and 100 W for radio frequency power. The excellent features of the results suggest that our systematic investigation on the organized growth factors and their effects on surface parameters and photoluminescence emission energy may constitute a basis for the tunable growth of Ge nanoislands (100 nanoislands suitable in nanophotonics.

  3. Combined Electrical, Optical and Nuclear Investigations of Impurities and Defects in II-VI Semiconductors

    CERN Multimedia


    % IS325 \\\\ \\\\ To achieve well controlled bipolar conductivity in II-VI semiconductors represents a fundamental problem in semiconductor physics. The doping problems are controversely discussed, either in terms of self compensation or of compensation and passivation by unintentionally introduced impurities. \\\\ \\\\It is the goal of our experiments at the new ISOLDE facility, to shed new light on these problems and to look for ways to circumvent it. For this aim the investigation of impurities and native defects and the interaction between each other shall be investigated. The use of radioactive ion beams opens the access to controlled site selective doping of only one sublattice via nuclear transmutation. The compensating and passivating mechanisms will be studied by combining nuclear, electrical and optical methods like Perturbed Angular Correlation~(PAC), Hall Effect~(HE), Deep Level Transient Spectroscopy~(DLTS), Photoluminescence Spectroscopy~(PL) and electron paramagnetic resonance (EPR). \\\\ \\\\We intend to ...

  4. Investigating the influence of chromatic aberration and optical illumination bandwidth on fundus imaging in rats (United States)

    Li, Hao; Liu, Wenzhong; Zhang, Hao F.


    Rodent models are indispensable in studying various retinal diseases. Noninvasive, high-resolution retinal imaging of rodent models is highly desired for longitudinally investigating the pathogenesis and therapeutic strategies. However, due to severe aberrations, the retinal image quality in rodents can be much worse than that in humans. We numerically and experimentally investigated the influence of chromatic aberration and optical illumination bandwidth on retinal imaging. We confirmed that the rat retinal image quality decreased with increasing illumination bandwidth. We achieved the retinal image resolution of 10 μm using a 19 nm illumination bandwidth centered at 580 nm in a home-built fundus camera. Furthermore, we observed higher chromatic aberration in albino rat eyes than in pigmented rat eyes. This study provides a design guide for high-resolution fundus camera for rodents. Our method is also beneficial to dispersion compensation in multiwavelength retinal imaging applications.

  5. Theoretical investigations on optical properties of magneto-optical thin film on ion-exchanged glass waveguide (United States)

    Hocini, Abdesselam; Bouras, Mounir; Amata, Hadi


    In this work, we report on the theoretical study of magneto-optical waveguides on an ion-exchanged glass waveguide, this latter is made by sol-gel process and doped with magnetic nanoparticles with two kinds of matrix (SiO2/TiO2 and SiO2/ZrO2). The mode propagation and the lateral light confinement for both polarizations TE and TM are simulated using software based on a film mode matching method. We propose from those results magneto-optical waveguides on ion-exchanged glass waveguide geometries for optical integrated applications.

  6. Prism coupling technique investigation of elasto-optical properties of thin polymer films

    NARCIS (Netherlands)

    Ay, Feridun; Kocabas, Askin; Kocabas, Coskun; Aydinli, Atilla; Agan, Sedat


    The use of thin polymer films in optical planar integrated optical circuits is rapidly increasing. Much interest, therefore, has been devoted to characterizing the optical and mechanical properties of thin polymer films. This study focuses on measuring the elasto-optical properties of three differen

  7. Theoretical investigation of the optical and magneto-optical properties of EuX (X=S, Se, and Te)

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Nirpendra [Department of Physics, Indian Institute of Technology Roorkee, Roorkee 247667, Uttranchal (India)]. E-mail:; Mohan Saini, Sapan [Department of Physics, Indian Institute of Technology Roorkee, Roorkee 247667, Uttranchal (India); Nautiyal, Tashi [Department of Physics, Indian Institute of Technology Roorkee, Roorkee 247667, Uttranchal (India); Auluck, Sushil [Department of Physics, Indian Institute of Technology Roorkee, Roorkee 247667, Uttranchal (India)


    The optical and magneto-optical (MO) properties of europium sulphide (EuS) have been studied by employing the full potential linearized augmented plane wave method as implemented in the WIEN2K code, with the Coulomb corrected local spin density approximation (LSDA+U) in the self-interaction correction (SIC). Our calculations give an energy gap of 1.58 eV for ferromagnetic semiconductor EuS in fair agreement with experiment. The calculated Faraday rotation spectrum of EuS is in better agreement with available experimental data, compared to a previous calculation. We have also performed calculations for EuSe and EuTe in the fictitious ferromagnetic phase with a view of exploring the effect of replacing S by Se and Te on the optical and magneto-optical properties.

  8. Investigations of the Rg-BrCl (Rg = He, Ne, Ar, Kr, Xe) binary van der Waals complexes: ab initio intermolecular potential energy surfaces, vibrational states and predicted pure rotational transition frequencies (United States)

    Li, Song; Zheng, Rui; Chen, Shan-Jun; Chen, Yan; Chen, Peng


    The intermolecular potential energy surfaces (PESs) of the ground electronic state for the Rg-BrCl (Rg = He, Ne, Ar, Kr, Xe) van der Waals complexes have been constructed by using the coupled-cluster method in combination with the augmented quadruple-zeta correlation-consistent basis sets supplemented with an additional set of bond functions. The features of the anisotropic PESs for these complexes are remarkably similar, which are characterized by three minima and two saddle points between them. The global minimum corresponds to a collinear Rg-Br-Cl configuration. Two local minima, correlate with an anti-linear Rg-Cl-Br geometry and a nearly T-shaped structure, can also be located on each PES. The quantum bound state calculations enable us to investigate intermolecular vibrational states and rotational energy levels of the complexes. The transition frequencies are predicted and are fitted to obtain their corresponding spectroscopic constants. In general, the periodic trends are observed for this complex family. Comparisons with available experimental data for the collinear isomer of Ar-BrCl demonstrate reliability of our theoretical predictions, and our results for the other two isomers of Ar-BrCl as well as for other members of the complex family are also anticipated to be trustable. Except for the collinear isomer of Ar-BrCl, the data presented in this paper would be beneficial to improve our knowledge for these experimentally unknown species.

  9. Investigations of the Rg-BrCl (Rg=He, Ne, Ar, Kr, Xe) binary van der Waals complexes: ab initio intermolecular potential energy surfaces, vibrational states and predicted pure rotational transition frequencies. (United States)

    Li, Song; Zheng, Rui; Chen, Shan-Jun; Chen, Yan; Chen, Peng


    The intermolecular potential energy surfaces (PESs) of the ground electronic state for the Rg-BrCl (Rg=He, Ne, Ar, Kr, Xe) van der Waals complexes have been constructed by using the coupled-cluster method in combination with the augmented quadruple-zeta correlation-consistent basis sets supplemented with an additional set of bond functions. The features of the anisotropic PESs for these complexes are remarkably similar, which are characterized by three minima and two saddle points between them. The global minimum corresponds to a collinear Rg-Br-Cl configuration. Two local minima, correlate with an anti-linear Rg-Cl-Br geometry and a nearly T-shaped structure, can also be located on each PES. The quantum bound state calculations enable us to investigate intermolecular vibrational states and rotational energy levels of the complexes. The transition frequencies are predicted and are fitted to obtain their corresponding spectroscopic constants. In general, the periodic trends are observed for this complex family. Comparisons with available experimental data for the collinear isomer of Ar-BrCl demonstrate reliability of our theoretical predictions, and our results for the other two isomers of Ar-BrCl as well as for other members of the complex family are also anticipated to be trustable. Except for the collinear isomer of Ar-BrCl, the data presented in this paper would be beneficial to improve our knowledge for these experimentally unknown species.

  10. Interaction of a pseudo-π C—C bond with cuprous and argentous chlorides: Cyclopropane⋯CuCl and cyclopropane⋯AgCl investigated by rotational spectroscopy and ab initio calculations

    Energy Technology Data Exchange (ETDEWEB)

    Zaleski, Daniel P.; Mullaney, John C.; Bittner, Dror M.; Walker, Nicholas R., E-mail:, E-mail: [School of Chemistry, Newcastle University, Bedson Building, Newcastle-Upon-Tyne NE1 7RU (United Kingdom); Tew, David P.; Legon, Anthony C., E-mail:, E-mail: [School of Chemistry, University of Bristol, Bristol BS8 1TS (United Kingdom)


    Strongly bound complexes (CH{sub 2}){sub 3}⋯MCl (M = Cu or Ag), formed by non-covalent interaction of cyclopropane and either cuprous chloride or argentous chloride, have been generated in the gas phase by means of the laser ablation of either copper or silver metal in the presence of supersonically expanded pulses of a gas mixture containing small amounts of cyclopropane and carbon tetrachloride in a large excess of argon. The rotational spectra of the complexes so formed were detected with a chirped-pulse, Fourier transform microwave spectrometer and analysed to give rotational constants and Cu and Cl nuclear quadrupole coupling constants for eight isotopologues of each of (CH{sub 2}){sub 3}⋯CuCl and (CH{sub 2}){sub 3}⋯AgCl. The geometry of each of these complexes was established unambiguously to have C{sub 2v} symmetry, with the three C atoms coplanar, and with the MCl molecule lying along a median of the cyclopropane C{sub 3} triangle. This median coincides with the principal inertia axis a in each of the two complexes (CH{sub 2}){sub 3}⋯MCl. The M atom interacts with the pseudo-π bond linking the pair of equivalent carbon atoms {sup F}C (F = front) nearest to it, so that M forms a non-covalent bond to one C—C edge of the cyclopropane molecule. The (CH{sub 2}){sub 3}⋯MCl complexes have similar angular geometries to those of the hydrogen- and halogen-bonded analogues (CH{sub 2}){sub 3}⋯HCl and (CH{sub 2}){sub 3}⋯ClF, respectively. Quantitative details of the geometries were determined by interpretation of the observed rotational constants and gave results in good agreement with those from ab initio calculations carried out at the CCSD(T)(F12*)/aug-cc-pVTZ-F12 level of theory. Interesting geometrical features are the lengthening of the {sup F}C—{sup F}C bond and the shrinkage of the two equivalent {sup B}C—{sup F}C (B = back) bonds relative to the C—C bond in cyclopropane itself. The expansions of the {sup F}C—{sup F}C bond are 0

  11. Investigations in silicate glasses. I. Radiation damage. II. Optical nonlinearity. [Gamma rays and electrons

    Energy Technology Data Exchange (ETDEWEB)

    Moran, M.J.


    The investigation of two poorly understood but technologically important physical properties of silicate glasses and related materials is described. The use of Electron Paramagnetic Resonance to investigate the nature of radiation-induced damage in glasses exposed to a variety of high-energy radiation sources is discussed first. Second, the measurement of the nonlinear index of refraction coefficient in a variety of optical materials related to the design of high-power laser systems is described. The radiation damage investigations rely heavily on the comparison of experimental results for different experimental situations. The comparison of EPR lineshapes, absolute spin densities and power saturation behavior is used to probe a variety of microscopic and macroscopic aspects of radiation damage in glasses. Comparison of radiation damage associated with exposure to gamma rays and fast neutrons (and combinations thereof) are interpreted in terms of the microscopic damage mechanisms which are expected to be associated with the specific radiations. Comparison of radiation damage behavior in different types of glasses is also interpreted in terms of the behavior expected for the specific materials. The body of data which is generated is found to be internally self-consistent and is also generally consistent with the radiation damage behavior expected for specific situations. A new and versatile technique for measuring the nonlinear index of refraction coefficient, n/sub 2/, in optical materials is described. The technique utilizes a 1 ns pulsed neodymium-glass laser system and time-resolved interferometry to determine the ratio of the coefficient n/sub 2/ of sample materials to the n/sub 2/ of CS/sub 2/. This method avoids some of the complications associated with performing absolute measurements of n/sub 2/ and allows the use of a relatively simple experimental technique. The measurements determine the nonlinear index ratios of the samples with an accuracy of about

  12. Time domain optical coherence tomography investigation of bone matrix interface in rat femurs (United States)

    Rusu, Laura-Cristina; Negruá¹±iu, Meda-Lavinia; Sinescu, Cosmin; Hoinoiu, Bogdan; Topala, Florin-Ionel; Duma, Virgil-Florin; Rominu, Mihai; Podoleanu, Adrian G.


    The materials used to fabricate scaffolds for tissue engineering are derived from synthetic polymers, mainly from the polyester family, or from natural materials (e.g., collagen and chitosan). The mechanical properties and the structural properties of these materials can be tailored by adjusting the molecular weight, the crystalline state, and the ratio of monomers in the copolymers. Quality control and adjustment of the scaffold manufacturing process are essential to achieve high standard scaffolds. Most scaffolds are made from highly crystalline polymers, which inevitably result in their opaque appearance. Their 3-D opaque structure prevents the observation of internal uneven surface structures of the scaffolds under normal optical instruments, such as the traditional light microscope. The inability to easily monitor the inner structure of scaffolds as well as the interface with the old bone poses a major challenge for tissue engineering: it impedes the precise control and adjustment of the parameters that affect the cell growth in response to various mimicked culture conditions. The aim of this paper is to investigate the interface between the femur rat bone and the new bone that is obtained using a method of tissue engineering that is based on different artificial matrixes inserted in previously artificially induced defects. For this study, 15 rats were used in conformity with ethical procedures. In all the femurs a round defect was induced by drilling with a 1 mm spherical Co-Cr surgical drill. The matrixes used were Bioss and 4bone. These materials were inserted into the induced defects. The femurs were investigated at 1 week, 1 month, 2 month and three month after the surgical procedures. The interfaces were examined using Time Domain (TD) Optical Coherence Tomography (OCT) combined with Confocal Microscopy (CM). The optical configuration uses two single mode directional couplers with a superluminiscent diode as the source centered at 1300 nm. The scanning

  13. Optics

    CERN Document Server

    Fincham, W H A


    Optics: Ninth Edition Optics: Ninth Edition covers the work necessary for the specialization in such subjects as ophthalmic optics, optical instruments and lens design. The text includes topics such as the propagation and behavior of light; reflection and refraction - their laws and how different media affect them; lenses - thick and thin, cylindrical and subcylindrical; photometry; dispersion and color; interference; and polarization. Also included are topics such as diffraction and holography; the limitation of beams in optical systems and its effects; and lens systems. The book is recommen

  14. Investigation of electronic structure and optical properties of MgAl2O4: DFT approach (United States)

    Reshak, A. H.; Khan, Saleem Ayaz; Alahmed, Z. A.


    The electronic band structure, electronic charge density distribution and optical properties of MgAl2O4 were calculated using the full potential linear augmented plane wave. The exchange correlation potential was solved by recently developed modified Becke Johnson potential in the framework of DFT. The band structure and partial density of states (PDOS) were calculated. The PDOS exhibit the role of orbital in bands formation and nature of the bonds. The calculated effective mass of electrons show high mobility of electrons in the conduction band minimum with respect to heavy and light holes. The calculated electron charge density confirm the existence of mixed ionic and covalent nature of the bonds. Mg-O show more ionicity because of greater electro-negativity difference than Al-O. Imaginary part of dielectric function ε2(ω) exhibit high transparency in the visible and infrared region. For further investigation of optical properties absorption coefficient I(ω), refractive index n(ω), reflectivity R(ω) and energy loss function L(ω) were calculated. We found reasonable agreement with the experimental data.

  15. Non-Intrusive Magneto-Optic Detecting System for Investigations of Air Switching Arcs (United States)

    Zhang, Pengfei; Zhang, Guogang; Dong, Jinlong; Liu, Wanying; Geng, Yingsan


    In current investigations of electric arc plasmas, experiments based on modern testing technology play an important role. To enrich the testing methods and contribute to the understanding and grasping of the inherent mechanism of air switching arcs, in this paper, a non-intrusive detecting system is described that combines the magneto-optic imaging (MOI) technique with the solution to inverse electromagnetic problems. The detecting system works in a sequence of main steps as follows: MOI of the variation of the arc flux density over a plane, magnetic field information extracted from the magneto-optic (MO) images, arc current density distribution and spatial pattern reconstruction by inverting the resulting field data. Correspondingly, in the system, an MOI set-up is designed based on the Faraday effect and the polarization properties of light, and an intelligent inversion algorithm is proposed that involves simulated annealing (SA). Experiments were carried out for high current (2 kA RMS) discharge cases in a typical low-voltage switchgear. The results show that the MO detection system possesses the advantages of visualization, high resolution and response, and electrical insulation, which provides a novel diagnostics tool for further studies of the arc.

  16. Design and investigation of a novel silicon/ferroelectric hybrid electro-optical microring modulator (United States)

    Qi, Zhipeng; Hu, Guohua; Liu, Chang; Li, Lei; Yun, Binfeng; Zhang, Ruohu; Cui, Yiping


    A silicon (Si) and lanthanum-doped lead zirconium titanate (PLZT) hybrid microring modulator based on silicon-on-insulator (SOI) platform is designed theoretically and investigated numerically in this paper. The heterogeneous integration of PLZT film with Si material enables the waveguide to acquire both excellent electro-optical property and strong mode confinement capacity. Such hybrid microring modulator (100 μm in radius) has a PLZT rib-loaded cladding and is integrated with optimized tuning electrodes. The simulation results demonstrated that the Si/PLZT hybrid microring modulator could operate at 14 GHz with a relative high modulation efficiency (<0.8 V cm), which is much better than the other proposed Si/ferroelectric modulators. Meanwhile, under a driving voltage of 20 V, our modulator exhibits an extinction ratio of 32 dB at 1550.22 nm wavelength and a resonant wavelength tunability of 25 pm/V for TE mode. With these outstanding performances, the Si/PLZT hybrid microring modulator holds a great potential as a reliable on-chip device for optical communications and links.

  17. Investigation of Structural Properties of Carbon-Epoxy Composites Using Embedded Fiber-Optic Bragg Gratings (United States)

    Osei, Albert J.


    coupled into the optical fiber sensor, a reflection peak will be obtained centered around a wavelength called Bragg-wavelength. The Bragg-wavelength depends on the refractive index and the period of the grating, which both change due to mechanical and thermal strain applied to the sensor. The shift in the Bragg-wavelength is directly proportional to the strain. Researchers at NASA MSFC are currently developing techniques for using FBGs for monitoring the integrity of advanced structural materials expected to become the mainstay of the current and future generation space structures. Since carbon-epoxy composites are the materials of choice for the current space structures, the initial study is concentrated on this type of composite. The goals of this activity are to use embedded FBG sensors for measuring strain and temperature of composite structures, and to investigate the effects of various parameters such as composite fiber orientation with respect to the optical sensor, unidirectional fiber composite, fabrication process etc., on the optical performance of the sensor. This paper describes an experiment to demonstrate the use of an embedded FBG for measuring strain in a composite material. The performance of the fiber optic sensor is determined by direct comparison with results from more conventional instrumentation.

  18. The electro-optical and charge transport study of imidazolidin derivative: Quantum chemical investigations

    Directory of Open Access Journals (Sweden)

    Ahmad Irfan


    Full Text Available Imidazolidin derivatives gained significant attention in our daily life from better biological activity to the semiconducting materials. The present investigation deals with the in depth study of (Z-2-sulfanylidene-5-(thiophen-2-ylmethylideneimidazolidin-4-one (STMI with respect to their structural, electronic, optical and charge transport properties as semiconducting material. The ground and first excited state geometries were optimized by applying density functional theory (DFT and time dependent DFT, respectively. The light has been shed on the frontier molecular orbitals (FMOs and observed comprehensible intramolecular charge transfer (ICT from the highest occupied molecular orbitals (HOMOs to the lowest unoccupied molecular orbitals (LUMOs. The absorption, emission, ionization potentials (IP, electron affinities (EA, total and partial densities of states and structure-property relationship have been discussed. Finally, hole as well as electron reorganization energies, transfer integrals and intrinsic mobilities have been calculated then charge transport behavior of STMI was discussed, intensively.

  19. Optical investigation of the hydrogenation and dehydrogenation mechanisms of evaporated MgNi films

    Energy Technology Data Exchange (ETDEWEB)

    Ell, Juergen [Freiburg Material Research Center, Stefan-Meier-Str. 21, D-79104 Freiburg (Germany); Georg, Andreas; Gombert, Andreas; Graf, Wolfgang; Wittwer, Volker [Fraunhofer Institute for Solar Energy Systems, Heidenhofstrasse 2, 79110 Freiburg (Germany); Arntzen, Markus [PSE GmbH - Forschung, Entwicklung, Marketing, Emmy-Noether-Strasse 2, 79072 Freiburg (Germany)


    We prepared thin films of magnesium nickel with a wide compositional range from pure magnesium to the intermetallic compound Mg{sub 2}Ni by e-beam evaporation. Capped with a thin Pd film such layers act as switchable mirrors upon exposure to gases containing hydrogen and oxygen. We investigated the reaction kinetics by measurement of the transmittance, and the reflectances both from the film side and the substrate side. We found that the hydrogenation kinetics and the optical performance are strongly dependent on the layer composition. The best results were obtained for Mg{sub 4}Ni to Mg{sub 8}Ni. It is shown that this is due to the different nucleation and growth behavior of the layers. (author)

  20. Theoretical and experimental investigations on the nonlinear optical properties of gold(III) dithiolene complexes (United States)

    Guezguez, I.; Karakas, A.; Iliopoulos, K.; Derkowska-Zielinska, B.; El-Ghayoury, A.; Ranganathan, A.; Batail, P.; Migalska-Zalas, A.; Sahraoui, B.; Karakaya, M.


    Degenerate four-wave mixing (DFWM) experiments have been performed to determine the third-order nonlinear optical (NLO) susceptibilities (χ(3)) of gold(III) maleimide dithiolate tetraphenylphosphonium, (PPh4)[Au(midt)2], (Au-P) and gold(III) maleimide dithiolate melamine melaminium hybrid solvate, (C3N6H6)(CNH7+)[Au(midt)2]-·2DMF·2H2O, (Au-Mel). Ab-initio quantum mechanical calculations (time-dependent Hartree-Fock (TDHF) method) of Au-P and Au-Mel have been carried out to compute the electric dipole moment (μ), the dispersion-free and frequency-dependent dipole polarizability (α) and the second hyperpolarizability (γ) values. These theoretical calculations are in good agreement with the experimentally obtained results by the DFWM technique. All the investigations show clearly the effect played by the counter ion on the resulting NLO properties of the two gold complexes.

  1. Feasibility investigation of integrated optics Fourier transform devices. [holographic subtraction for multichannel data preprocessing (United States)

    Verber, C. M.; Vahey, D. W.; Wood, V. E.; Kenan, R. P.; Hartman, N. F.


    The possibility of producing an integrated optics data processing device based upon Fourier transformations or other parallel processing techniques, and the ways in which such techniques may be used to upgrade the performance of present and projected NASA systems were investigated. Activities toward this goal include; (1) production of near-diffraction-limited geodesic lenses in glass waveguides; (2) development of grinding and polishing techniques for the production of geodesic lenses in LiNbO3 waveguides; (3) development of a characterization technique for waveguide lenses; and (4) development of a theory for corrected aspheric geodesic lenses. A holographic subtraction system was devised which should be capable of rapid on-board preprocessing of a large number of parallel data channels. The principle involved is validated in three demonstrations.

  2. Investigation of Coherent Multicarrier Code Division Multiple Access for Optical Access Networks

    Directory of Open Access Journals (Sweden)

    Ali Tamini


    Full Text Available Orthogonal frequency division multiplexing (OFDM has proved to be a promising technique to increase the reach and bit rate both in long‑haul communications and in passive optical networks. This paper, for the first time, investigates the use of OFDM combined with electrical CDMA in presence of coherent detection as a multiple access scheme. The proposed multicarrier‑CDMA system is simulated using Walsh‑Hadamard codes and its performance is compared to that of coherent WDM-OFDM system in terms of bit‑error‑rate and bandwidth efficiency. It is shown that MC‑CDMA benefits from better spectral efficiency while its performance slightly deteriorates in comparison to WDM-OFDM when the number of users is increased.

  3. Supersonic metal plasma impact on a surface: An optical investigation of the pre-surface region

    Energy Technology Data Exchange (ETDEWEB)

    Fusion Science Group, AFRD; Plasma Applications Group, AFRD; Ni, Pavel A.; Anders, Andre


    Aluminum plasma, produced in high vacuum by a pulsed, filtered cathodic arc plasma source, was directed onto a wall where if formed a coating. The accompanying ?optical flare? known from the literature was visually observed, photographed, and spectroscopically investigated with appropriately high temporal (1 ?s) and spatial (100 ?m) resolution. Consistent with other observations using different techniques, it was found that the impact of the fully ionized plasma produces metal neutrals as well as desorbed gases, both of which interact with the incoming plasma. Most effectively are charge exchange collisions between doubly charged aluminum and neutral aluminum, which lead to a reduction of the flow of doubly charged before they reach the wall, and a reduction of neutrals as the move away from the surface. Those plasma-wall interactions are relevant for coating processes as well as for interpreting the plasma properties such as ion charge state distributions.

  4. Optical and THz investigations of mid-IR materials exposed to alpha particle irradiation (United States)

    Sporea, Dan; Mihai, Laura; Sporea, Adelina; Vâţã, Ion


    The paper is the first comprehensive study on alpha particle irradiation effects on four mid-IR materials: CaF2, BaF2, Al2O3 (sapphire) and ZnSe. The measurements of the optical spectral transmittance, spectral diffuse reflectance, radioluminescent emission, terahertz (THz) spectral response, transmittance, absorbance, refractive index, real and imaginary parts of the dielectric constant and THz imaging are used as complementary investigations to evaluate these effects. The simulations were run to estimate: (i) the penetration depth, (ii) the scattering of alpha particle beam, (iii) the amount of material affected by this interaction, and (iv) the number of vacancies produced by the radiation exposure for each type of material. The simulation results are compared to the off-line measurement outcomes. The delay and spectral composition change of the reflected THz signal highlight the modification induced in the tested materials by the irradiation process.

  5. Optical and THz investigations of mid-IR materials exposed to alpha particle irradiation (United States)

    Sporea, Dan; Mihai, Laura; Sporea, Adelina; Vâţã, Ion


    The paper is the first comprehensive study on alpha particle irradiation effects on four mid-IR materials: CaF2, BaF2, Al2O3 (sapphire) and ZnSe. The measurements of the optical spectral transmittance, spectral diffuse reflectance, radioluminescent emission, terahertz (THz) spectral response, transmittance, absorbance, refractive index, real and imaginary parts of the dielectric constant and THz imaging are used as complementary investigations to evaluate these effects. The simulations were run to estimate: (i) the penetration depth, (ii) the scattering of alpha particle beam, (iii) the amount of material affected by this interaction, and (iv) the number of vacancies produced by the radiation exposure for each type of material. The simulation results are compared to the off-line measurement outcomes. The delay and spectral composition change of the reflected THz signal highlight the modification induced in the tested materials by the irradiation process. PMID:28067289

  6. Theoretical Investigation of Nonlinear Optical Properties of Organic and Transition Metal Hybrid Azobenzene Dendrimers

    Institute of Scientific and Technical Information of China (English)

    LIU Cai-Ping; LIU Ping; WU Ke-Chen


    In this work, we report a theoretical exploration of the responses of organic azo-benzene dendrimers. The polarizabilities, the first and second hyperpolarizabilities of the azobenzene monomers (GO), and the first, second and third generation (G1, G2 and G3, respectively) are investigated by semi-empirical methods. The calculated results show that the nonlinear optical (NLO)properties of these organic dendrimers are mainly determined by the azobenzene chromospheres.Additionally, the values of β and γ increase almost in proportion to the number of chromophores. On the other hand, two types of transition metal hybrid azobenzene dendrimers (core-hybrid and branch-end hybrid according to the sites combined with transition metals) are simulated and discussed in detail in the framework of time-dependent density functional theory (TDDFT). The calculated results reveal that the NLO responses of these metal dendrimers distinctly varied as a result of altering the charge transfer transition scale and the excitation energies.

  7. Investigating the growth mechanism and optical properties of carbon-coated titanium dioxide nanoparticles

    KAUST Repository

    Anjum, Dalaver H.


    TiO2 nanoparticles (NPs) were prepared using flame synthesis and then characterized using transmission electron microscopy. We found that the flame method yields both crystalline TiO2 and amorphous TiO 2 NPs. TEM analysis revealed that only the crystalline TiO 2 NPs were coated with carbon. Based on this observation, we proposed a growth model for the diffusion and precipitation of carbon atoms in TiO 2 NPs. The optical properties of TiO2 NPs were investigated by performing valence electron energy loss spectrometry analysis. We observed that carbon-coated TiO2 NPs have higher absorption in the visible range due to their lower band-gap energy. © 2013 Elsevier B.V.

  8. Investigation of PMD in direct-detection optical OFDM with zero padding. (United States)

    Li, Xiang; Alphones, Arokiaswami; Zhong, Wen-De; Yu, Changyuan


    We investigate the polarization-mode dispersion (PMD) effect of zero padding OFDM (ZP-OFDM) in direct-detection optical orthogonal frequency division multiplexing (DDO-OFDM) systems. We first study the conventional equalization method for ZP-OFDM. Then an equalization method based on sorted QR decomposition is proposed to further improve the performance. It is found that the performance improvement of ZP-OFDM is due to the frequency domain oversampling (FDO) induced inter-carrier interference (ICI). Numerical simulation results show that compared with cyclic prefix OFDM (CP-OFDM), ZP-OFDM has a significantly higher tolerance to PMD in DDO-OFDM systems when the channel spectral nulls occur at certain differential group delay (DGD) values.

  9. Synthesis, crystal structure and optical property of a novel metal chalcohalide: ZnHg{sub 3}Se{sub 2}Cl{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Guodong; Xiong, Wei-Wei; Nie, Lina [School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798 (Singapore); Zhang, Qichun, E-mail: [School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798 (Singapore); Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371 (Singapore)


    A novel chalcohalide ZnHg{sub 3}Se{sub 2}Cl{sub 4} has been synthesized through a solid state method and structurally characterized by single-crystal X-ray diffraction. It crystallizes in the acentric space group Cmc2{sub 1} (No. 36) with cell parameters a=7.3262(8) Å, b=12.518(2) Å, c=11.3324(14) Å. The compound consists of 12-membered Hg{sub 6}Se{sub 6} rings edge-sharing with six neighbored rings to construct a 2D layered network and the ZnCl{sub 4} tetrahedra are sandwiched between layers. TG-DTA measurement shows that the compound is thermally stable up to 300 °C. The band gap of the crystal is about 2.23 eV, and the crystal exhibits a broad transparent range from 0.56 to 13.8 µm. - Highlights: • A novel chalcohalide ZnHg{sub 3}Se{sub 2}Cl{sub 4} was synthesized by a solid state method. • The structure contains 12-membered Hg{sub 6}Se{sub 6} rings and ZnCl{sub 4} tetrahedra. • The band gap of the as-prepared compound is about 2.23 eV.

  10. Magneto-optical investigation of the shape anisotropy of individual micron-sized magnetic elements (United States)

    Sebastian, T.; Conca, A.; Wolf, G.; Schultheiss, H.; Leven, B.; Hillebrands, B.


    In this work, the anisotropy of individual microstructured magnetic elements has been investigated. The investigated elements are of elliptical shape with different sizes and aspect ratios (AR), structured from a 5-nm-thick permalloy (Ni80 Fe20) film. For the measurements, a new magneto-optical Kerr effect (MOKE) magnetometer was used. To allow for the investigation of individual microstructured elements, a micro-focused probing laser beam (spatial resolution ≈1μm) has been combined with a self-stabilizing positioning system of high accuracy, including a rotating unit. Hysteresis loops can be taken for varying orientation of the symmetry axes of the magnetic elements relative to the applied field. For the characterization of the anisotropy, the coercive field as a function of the magnetization direction is extracted from the corresponding hysteresis loops. These results make a quantitative and systematic study of the influence of the shape anisotropy on the magnetic behavior of microstructures possible. The experimental data has been compared to an extended Stoner-Wohlfarth model.

  11. Investigation of Ionic Conductivity of Nanocomposite Polymer Electrolytes Based On PVDF-HFP/PVC Blend, LiClO4 and TiO2 Nanofiller (United States)

    Basri, N. H.; Mohamed, N. S.


    The effects of nanosized TiO2 on the conductivity of PVDF-HFP/PVC-LiClO4 was studied by means of impedance spectroscopy and x-ray diffraction (XRD). The addition of TiO2 nanofiller increases the crystalline phase fraction but slightly increases the conductivity of the PVDF-HFP/PVC-LiClO4 complex. The increase in conductivity is attributed to the formation of highly conducting layer at the electrolyte/filler interface. The temperature dependence of conductivity obeys the VTF type behaviour while the transference number confirms that the electrolyte containing 6 wt.% TiO2 is an ionic conductor are ionic conductors.

  12. Optics

    CERN Document Server

    Fincham, W H A


    Optics: Eighth Edition covers the work necessary for the specialization in such subjects as ophthalmic optics, optical instruments and lens design. The text includes topics such as the propagation and behavior of light; reflection and refraction - their laws and how different media affect them; lenses - thick and thin, cylindrical and subcylindrical; photometry; dispersion and color; interference; and polarization. Also included are topics such as diffraction and holography; the limitation of beams in optical systems and its effects; and lens systems. The book is recommended for engineering st

  13. Investigation of Hg/sub 2/ as a discharge pumped optical storage medium

    Energy Technology Data Exchange (ETDEWEB)

    Ehrlich, D J; Osgood, Jr, R M


    The report describes work performed in the period 1 October 1977 to 30 September 1978 on the extraction of energy from metastable Hg/sub 2/ by optical techniques. The major accomplishments have included: (1) assessment of optical extraction techniques for laser fusion applications; (2) demonstration of 20X enhancements in the population of the UV-radiating level by optical pumping with mid-IR lasers; (3) analysis of the IR optical pumping process through the induced emission spectrum; (4) parametric studies of the excitation wavelength, temperature and pressure dependences of extraction by optical pumping; (5) studies of the saturation of mid-IR optical pumping; (6) modeling of large-scale extraction for laser fusion applications; (7) studies of optical pumping of Hg/sub 2/ by high power ArF laser (193 nm) radiation; and (8) studies of Hg/sub 2/ excimer structure and collisional destruction rates.

  14. Nano-spatial parameters from 3D to 2D lattice dimensionality by organic variant in [ZnCl4]- [R]+ hybrid materials: Structure, architecture-lattice dimensionality, microscopy, optical Eg and PL correlations (United States)

    Kumar, Ajit; Verma, Sanjay K.; Alvi, P. A.; Jasrotia, Dinesh


    The nanospatial morphological features of [ZnCl]- [C5H4NCH3]+ hybrid derivative depicts 28 nm granular size and 3D spreader shape packing pattern as analyzed by FESEM and single crystal XRD structural studies. The organic moiety connect the inorganic components through N-H+…Cl- hydrogen bond to form a hybrid composite, the replacement of organic derivatives from 2-methylpyridine to 2-Amino-5-choloropyridine results the increase in granular size from 28nm to 60nm and unit cell packing pattern from 3D-2D lattice dimensionality along ac plane. The change in optical energy direct band gap value from 3.01eV for [ZnCl]- [C5H4NCH3]+ (HM1) to 3.42eV for [ZnCl]- [C5H5ClN2]+ (HM2) indicates the role of organic moiety in optical properties of hybrid materials. The photoluminescence emission spectra is observed in the wavelength range of 370 to 600 nm with maximum peak intensity of 9.66a.u. at 438 nm for (HM1) and 370 to 600 nm with max peak intensity of 9.91 a.u. at 442 nm for (HM2), indicating that the emission spectra lies in visible range. PL excitation spectra depicts the maximum excitation intensity [9.8] at 245.5 nm for (HM1) and its value of 9.9 a.u. at 294 nm, specify the excitation spectra lies in UV range. Photoluminescence excitation spectra is observed in the wavelength range of 280 to 350 nm with maximum peak intensity of 9.4 a.u. at 285.5 nm and 9.9 a.u. at 294 and 297 nm, indicating excitation in the UV spectrum. Single crystal growth process and detailed physiochemical characterization such as XRD, FESEM image analysis photoluminescence property reveals the structure stability with non-covalent interactions, lattice dimensionality (3D-2D) correlations interweaving into the design of inorganic-organic hybrid materials.


    Directory of Open Access Journals (Sweden)

    S. Robinson


    Full Text Available Free Space Optical (FSO communication is being realized as an effective solution for future accessing networks, offering light passed through air. The performance of FSO can be primarily degraded by various atmospheric attenuation namely, rain, fog, haze and snow. At present, hybridization of Dense Wavelength Division Multiplexing (DWDM with Coarse Wavelength Division Multiplexing (CWDM becomes necessary to scale the speed and high bandwidth of the services. In this paper, hybrid WDM system is proposed, designed and the network parameters such as Bit Error Rate (BER, Quality Factor and receiver sensitivity are analyzed with respect to link distance for various weather conditions. For investigation, 4 CWDM and 8 DWDM channels are considered whose corresponding channel spacing is 20nm and 0.8nm, respectively. From the simulation, it is investigated that the average link distance of proposed hybrid WDM-FSO system for DWDM and CWDM system at very clear condition are around 810km and 780km. The proposed hybrid WDM based FSO system is designed to handle the quality of transmission for 12 users, each at a data rate of 2.5Gbps.

  16. Investigation of the effect of Mg doping for improvements of optical and electrical properties

    Energy Technology Data Exchange (ETDEWEB)

    Caglar, Mujdat, E-mail:; Caglar, Yasemin; Ilican, Saliha


    Sol–gel spin coating method was used for the deposition of nanostructured undoped and Mg doped ZnO films. The effects of magnesium incorporation on the crystalline structure were investigated by XRD measurements and the structural deterioration was observed in the crystalline quality of the films with respect to increasing in Mg doping. All the samples exhibited a wurtzite structure. From the scanning electron microscopy (SEM) images obtained to investigate the surface morphology it was detected that an increase in Mg doping caused an improvement on the surface roughness and a reduction in the number of voids on the surface. To evaluate the absorption edges of the produced samples depending on the Mg, different methods were used and according to the obtained results, a shifting towards to high energies for the optical band gap was observed in each method. By using the single oscillator model, developed by DiDomenico and Wemple, the refractive index dispersion of the films was analyzed. E{sub o} and E{sub d} values of the 5% Mg doped film were found to be 5.76 eV and 11.80 eV, respectively. Within the scope of electrical properties, from Hall effect measurements, it was determined that all the films exhibited n-type behavior and the carrier concentration increased from 1.49×10{sup 16} to 1.20×10{sup 17} cm{sup −3} with increasing Mg doping.

  17. New potentialities for noninvasive optical investigation of microcirculation in extended space missions (United States)

    Gurfinkel, Youri I.; Mikhailov, Valery M.


    Goals of the investigation were to analyze the spectrum of microcirculation parameters and collection of baseline data healthy subjects during extended isolation and relative hypokinesia as a model of mission to the International space station. There were investigated four healthy volunteers at the age of 37, 40, 41 and 48 during the baseline 240-d isolation period starting from July 3, 1999. With the regularity of 3 times a week each subject made records at the same time between 1 and 2 pm. Optical computerized capillaroscope for noninvasive measurement of the capillary diameters, blood flow velocity as well as the size of the perivascular zone and the number of the blood aggregates was used. About 1500 episodes were recorded on laser disks and analyzed. Parameters of microcirculation were compared with other physiological parameters monitored in the experiment. All subjects had wave-like variations in the microcirculation parameters within the minute, week, and month ranges. Mean blood flow velocity in the baseline period was lower than in the period of isolation. Results of the daily body mass measurement were found to correlate with the perivascular zone size, that could be explained as retention of body fluids in tissues. Computerized capillaroscopy is easy to perform, noninvasive, highly sensitive and informative. It enables analysis of the character of rhythmic processes, adaptability of organism to long-term experiments and, therefore, can be proposed for use in extended space missions.

  18. An Investigation of the 40Ar(n,p)40Cl Reaction Cross-Section below 50MeV at Crocker Nuclear Laboratory (United States)

    Walsh, Nicholas Ian

    Large underground liquid argon detectors are poised to detect neutrinos from the next galactic supernova. Liquid argon detectors are uniquely sensitive to the electron neutrino, thus giving them the capability to detect neutronization neutrinos for the first time. One background that may mimic the signal of this low-energy neutrino interaction in argon is the beta-decay of Cl-40 which is produced in argon by a fast neutron reaction. Previous measurements of this 40Ar+n->40Cl+p reaction cross section exist only below 15 MeV and the measurements differ by a factor of two. Using the U.C. Davis Crocker Nuclear Laboratory neutron beam this cross-section is determined by fitting to a parametrized model for neutron energies up to 50 MeV. Neutrons at this facility are generated from mono-energetic protons impinging on a thick beryllium target. Then, the neutrons that pass through the collimator are measured by time-of-flight and a fast-neutron activation technique. Using the neutron fluxes generated from five different proton energies, including 50 MeV protons, the 40Ar(n,p)40Cl reaction cross section is measured by irradiating liquid argon in each beam and counting the subsequent gammas from the Cl-40 decay in a high-purity germanium detector.

  19. Numerical investigation of optical Tamm states in two-dimensional hybrid plasmonic-photonic crystal nanobeams (United States)

    Meng, Zi-Ming; Hu, Yi-Hua; Ju, Gui-Fang; Zhong, Xiao-Lan; Ding, Wei; Li, Zhi-Yuan


    Optical Tamm states (OTSs) in analogy with its electronic counterpart confined at the surface of crystals are optical surface modes at the interfaces between uniform metallic films and distributed Bragg reflectors. In this paper, OTSs are numerically investigated in two-dimensional hybrid plasmonic-photonic crystal nanobeams (HPPCN), which are constructed by inserting a metallic nanoparticle into a photonic crystal nanobeam formed by periodically etching square air holes into dielectric waveguides. The evidences of OTSs can be verified by transmission spectra and the field distribution at resonant frequency. Similar to OTSs in one-dimensional multilayer structures OTSs in HPPCN can be excited by both TE and TM polarization. The physical origin of OTSs in HPPCN is due to the combined contribution of strong reflection imposed by the photonic band gap (PBG) of the photonic crystal (PC) nanobeam and strong backward scattering exerted by the nanoparticle. For TE, incidence OTSs can be obtained at the frequency near the center of the photonic band gap. The transmissivity and the resonant frequency can be finely tuned by the dimension of nanoparticles. While for TM incidence OTSs are observed for relatively larger metallic nanoparticles compared with TE polarization. The differences between TE and TM polarization can be explained by two reasons. For one reason stronger backward scattering of nanoparticles for TE polarization can be achieved by the excitation of localized surface plasmon polariton of nanoparticles. This assumption has been proved by examining the scattering, absorption, and extinction cross section of the metallic nanoparticle. The other can be attributed to the deep and wide PBG available for TE polarization with less number of air holes compared with TM polarization. Our results show great promise in extending the application scope of OTSs from one-dimensional structures to practical integrated photonic devices and circuits.

  20. An experimental and theoretical investigation on the optical and photocatalytic properties of ZnS nanoparticles (United States)

    La Porta, F. A.; Nogueira, A. E.; Gracia, Lourdes; Pereira, W. S.; Botelho, G.; Mulinari, T. A.; Andrés, Juan; Longo, E.


    From the viewpoints of materials chemistry and physical chemistry, crystal structure directly determines the electronic structure and furthermore their optical and photocatalytic properties. Zinc sulfide (ZnS) nanoparticles (NPs) with tunable photoluminescence (PL) emission and high photocatalytic activity have been obtained by means of a microwave-assisted solvothermal (MAS) method using different precursors (i.e., zinc nitrate (ZN), zinc chloride (ZC), or zinc acetate (ZA)). The morphologies, optical properties, and electronic structures of the as-synthesized ZnS NPs were characterized by X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), Brunauer-Emmett-Teller (BET) isotherms for N2 adsorption/desorption processes, diffuse reflectance spectroscopy (DRS), PL measurements and theoretical calculations. Density functional theory calculations were used to determine the geometries and electronic properties of bulk wurtzite (WZ) ZnS NPs and their (0001), (101 ̅0), (112 ̅0), (101 ̅1), and (101 ̅2) surfaces. The dependence of the PL emission behavior of ZnS NPs on the precursor was elucidated by examining the energy band structure and density of states. The method for degradation of Rhodamine B (RhB) was used as a probe reaction to investigate the photocatalytic activity of the as-Synthesised ZnS NPs under UV light irradiation. The PL behavior as well as photocatalytic activities of ZnS NPs were attributed to specific features of the structural and electronic structures. Increased photocatalytic degradation was observed for samples synthesized using different precursors in the following order: ZA

  1. INTERACTION OF LASER RADIATION WITH MATTER: Influence of Ca and Pb impurities on the bulk optical strength of ultrapure NaCl and KCl crystals (United States)

    Vinogradov, An V.; Voszka, R.; Kovalev, Valerii I.; Faĭzullov, F. S.; Janszky, J.


    A significant increase (by a factor of about 3) of the bulk damage threshold in the case of interaction of CO2 laser radiation pulses with ultrapure NaCl and KCl crystals grown in a reactive atmosphere was observed on introduction of divalent metal ions Ca and Pb in concentrations of 10-5-10-6 mol/mol. Impurities were introduced in concentrations of 10-8-10-3 and 2×10-7-10-4 mol/mol into the melts of KCl and NaCl, respectively. The concentration of other impurities (including OH) did not exceed ~10-6 mol/mol. A physical model was developed to account for the observed dependence on the basis of an analogy between a system of colloidal particles and F centers in a crystal and a liquid-vapor system.

  2. Development of a scanning nearfield optical microscope for low-temperature investigations of semiconductor nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Hodeck, Kai Friedrich


    In the present work the electronic structure of MOCVD-grown InGaAs/GaAs and InAs/GaAs quantum dots which are characterized by a particularly low ground state transition energy, was investigated using Scanning Nearfield Optical Microscopy (SNOM). The pivotal question of the presented investigations is, which influence the interaction of the confined carriers has on the energy states of the biexcitons and the multiexcitons in a quantum dot. Therefore, photoluminescence spectra of single quantum dots were investigated under varying excitation intensity at different temperatures between 5 K and 300 K. The construction of a novel scanning nearfield microscope especially for low temperatures allowed the investigation of single quantum dots. Due to significant improvements of the positioning technology and the shear-force distance control between the sample and the nearfield probe a stable scanning of the quantum dot samples at 5 K could be demonstrated, showing a lateral optical resolution of 200 nm. This way, in the photoluminescence spectroscopy of single quantum dots the thermal linewidth broadening of the detected light was reduced down to a value of less than 1 meV, which allowed the identification of the transitions of biexcitons and multiexcitons. On the basis of the performed measurements, for the InGaAs/GaAs quantum dots a biexciton state was identified, with variable binding energies of 2-7 meV. Furthermore, a positively charged trion state with a binding energy of 11 meV was observed, showing high emission intensity, which can be assigned to the sample doping. Accordingly, for the positively charged biexciton state a binding energy of 11 meV can be announced. For the investigated InAs/GaAs quantum dots a biexciton state with binding energies of 3-4 meV was found. Some of the investigated InAs/GaAs quantum dots showed the formation of positively charged states, in particular of a trion state with a binding energy of 3 meV, and of the positively charged

  3. Investigating quartz optically stimulated luminescence dose-response curves at high doses

    Energy Technology Data Exchange (ETDEWEB)

    Lowick, Sally E., E-mail: lowick@geo.unibe.c [Institut fuer Geologie, Universitaet Bern, Baltzerstrasse 1-3, 3012 Bern (Switzerland); Preusser, Frank [Institut fuer Geologie, Universitaet Bern, Baltzerstrasse 1-3, 3012 Bern (Switzerland); Wintle, Ann G. [Institute of Geography and Earth Sciences, Aberystwyth University, AberystwythSY23 3DB (United Kingdom)


    Despite the general expectation that optically stimulated luminescence (OSL) growth should be described by a simple saturating exponential function, an additional high dose component is often reported in the dose response of quartz. Although often reported as linear, it appears that this response is the early expression of a second saturating exponential. While some studies using equivalent doses that fall in this high dose region have produced ages that correlate well with independent dating, others report that it results in unreliable age determinations. Two fine grain sedimentary quartz samples that display such a response were used to investigate the origin of this additional high dose component: three experiments were conducted to examine their dose-response up to >1000 Gy. The high dose rates provided by laboratory irradiation were found not to induce a sensitivity change in the response to a subsequent test dose, with the latter not being significantly different from those generated following naturally acquired doses. The relative percentage contributions of the fast and medium OSL components remained fixed throughout the dose-response curve, suggesting that the electron traps that give rise to the initial OSL do not change with dose. An attempt was made to investigate a change in luminescence centre recombination probability by monitoring the depletion of the '325 {sup o}C' thermoluminescence (TL) during the optical stimulation that would result in depletion of the OSL signal. The emissions measured through both the conventional ultraviolet (UV), and a longer wavelength violet/blue (VB) window, displayed similar relative growth with dose, although it was not possible to resolve the origin of the VB emissions. No evidence was found to indicate whether the additional component at high doses occurs naturally or is a product of laboratory treatment. However, it appears that these samples display an increased sensitivity of quartz OSL to high doses

  4. Optical contouring of an acrylic surface for non-intrusive diagnostics in pipe-flow investigations (United States)

    de Witt, Benjamin J.; Coronado-Diaz, Haydee; Hugo, Ronald J.


    In this work, an acrylic surface was optically contoured to correct for the optical distortion caused by a transparent pipe wall. This method can be applied to non-invasive viewing/imaging techniques for fluid flow experiments. Software tools were developed to aid in the design of an optically contoured acrylic test section for pipe-flow experiments. Numerical models were computed for a standard acrylic pipe, inner diameter 57.15 mm, with water enclosed. An optical contour prototype was machined on a 5-axis CNC machine, and polished with 1-15 μm diamond paste, alleviating any surface imperfections without significantly altering the contoured surface. Experiments were then performed to measure the emerging optical wavefront and was found to emerge planar when utilizing the optical contour. It was determined that the wavefront was corrected to within ten wavelengths of a Helium-Neon (He-Ne) laser beam.

  5. Investigation of local and nonlocal nonlinear optical refraction effect in IZO thin films (United States)

    Htwe, Zin Maung; Zhang, Yun-Dong; Yao, Cheng-Bao; Li, Hui; Yuan, Ping


    We report the local and nonlocal nonlinear optical refraction properties of indium doped zinc oxide (IZO) thin films using closed aperture Z-scan technique. The Z-scan results show the films have positive nonlinear optical refraction properties. The nonlocal parameter m of samples is increased with indium. In both of local and nonlocal studies, the nonlinear optical refractions of thin films were increased with In contents and laser energy. This relation reveals the role of In composition in IZO affects on the nonlinear optical responses of the films. These results make the IZO thin films as the promising application in optoelectronics devices.

  6. Investigation of the limits of a fibre optic sensor system for measurement of temperature distribution

    DEFF Research Database (Denmark)

    Brehm, Robert; Johnson, Frank


    The aim of this project is to develop an innovative temperature sensor system which is able to measure the temperature distribution along a fibre optical cable. This technique for temperature measurement is based on Optical Time Domain Reflectometry (OTDR). ©2006 IEEE.......The aim of this project is to develop an innovative temperature sensor system which is able to measure the temperature distribution along a fibre optical cable. This technique for temperature measurement is based on Optical Time Domain Reflectometry (OTDR). ©2006 IEEE....

  7. An ab initio investigation of vibrational, thermodynamic, and optical properties of Sc 2 AlC MAX compound (United States)

    Ali, M. A.; Nasir, M. T.; Khatun, M. R.; Islam, A. K. M. A.; Naqib, S. H.


    The structural vibrational, thermodynamical, and optical properties of potentially technologically important, weakly coupled MAX compound, Sc2AlC are calculated using density functional theory (DFT). The structural properties of Sc2AlC are compared with the results reported earlier. The vibrational, thermodynamical, and optical properties are theoretically estimated for the first time. The phonon dispersion curve is calculated and the dynamical stability of this compound is investigated. The optical and acoustic modes are observed clearly. We calculate the Helmholtz free energy (F), internal energy (E), entropy (S), and specific heat capacity (Cv ) from the phonon density of states. Various optical parameters are also calculated. The reflectance spectrum shows that this compound has the potential to be used as an efficient solar reflector.

  8. Investigation on luminescence properties of Eu2+-doped Ba3Al2O5Cl2 phosphor for near-UV-excited white LEDs. (United States)

    Pawade, V B; Dhoble, S J


    Ba3Al2O5Cl2:Eu(2+) phosphor was prepared by combustion synthesis (CS). The prepared phosphor was excited at 329 nm; the phosphors shows an efficient bluish-green wide-band emission centred at 490 nm, which originates from the 4f(6)d(1)  →  4f(7) transition of Eu(2+) ions. The excitation spectra of the phosphors have a band centred at 329 nm. It was also characterized by XRD, FT-IR for confirmation of phase purity, and FT-IR analysis indicated the vibrations of metal-oxygen (M-O) groups. SEM shows the morphology of the phosphor at the submicron scale. The results indicate that Ba3Al2O5Cl2:Eu(2+) phosphor may be applicable for solid-state lighting purposes.

  9. Investigation of concentration-dependence of thermodynamic properties of lanthanum, yttrium, scandium and terbium in eutectic LiCl-KCl molten salt (United States)

    Wang, Yafei; Zhou, Wentao; Zhang, Jinsuo


    Thermodynamic properties of rare earth metals in LiCl-KCl molten salt electrolyte are crucial to the development of electrochemical separation for the treatment of used nuclear fuels. In the present study, activity coefficient, apparent potential, and diffusion coefficient of lanthanum, yttrium, scandium, and terbium in the molten salt (58 at% LiCl and 42 at% KCl) were calculated by the method of molecular dynamics simulation up to a concentration around 3 at% at temperatures of 723 K and 773 K. It was found that the activity coefficient and the apparent potential increase with the species concentration while diffusion coefficient shows a trend of increase followed by decrease. The calculated results were validated by available measurement data of dilution cases. This research extends the range of data to a wide component and would provide further insight to the pyroprocessing design and safeguards.

  10. Investigation of Structural, Magnetic, and Optical Properties of ZnO Codoped with Co and Cd

    Directory of Open Access Journals (Sweden)

    Lubna Mustafa


    Full Text Available Co and Cd have been codoped in ZnO using a simple solid state reaction technique to synthesize dilute magnetic oxide semiconductors of composition Zn0.9Co0.1−xCdxO (x = 0.0-0.1 with an increment of 0.02. Hexagonal wurtzite structure has been obtained for samples up to x = 0.06, using X-ray diffractometry. However, at x = 0.08 and 0.1, secondary peak of CdO is observed. Raman spectra of the samples have been obtained in 200–800 cm−1 range. UV-VIS spectrophotometer is used to study the optical properties, which shows that band gap energy decreases with the increase in Cd concentration. A weak ferromagnetic behavior was evident which decreased further by adding Cd in the series. Room temperature resistivity measurements performed using four-point probe technique showed that their values lie in the semiconductor range. Structural morphology of the samples has been investigated by a scanning electron microscope and grain size has been determined. Raman spectra and Fourier transform infrared spectroscopy revealed the successful incorporation of Co and Cd ions into the host ZnO lattice.

  11. Experimental investigation on the high chip rate of 2D incoherent optical CDMA system (United States)

    Su, Guorui; Wang, Rong; Pu, Tao; Fang, Tao; Zheng, Jilin; Zhu, Huatao; Wu, Weijiang


    An innovative approach to realise high chip rate in OCDMA transmission system is proposed and experimentally investigation, the high chip rate is achieved through a 2-D wavelength-hopping time-spreading en/decoder based on the supercontinuum light source. The source used in the experiment is generated by high nonlinear optical fiber (HNLF), Erbium-doped fiber amplifier (EDFA) which output power is 26 dBm, and distributed feed-back laser diode which works in the gain switch state. The span and the flatness of the light source are 20 nm and 3 dB, respectively, after equalization of wavelength selective switch (WSS). The wavelength-hopping time-spreading coder can be changed 20 nm in the wavelength and 400 ps in the time, is consist of WSS and delay lines. Therefore, the experimental results show that the chip rate can achieve 500 Gchip/s, in the case of 2.5 Gbit/s, while keeping a bit error rate below forward error correction limit after 40 km transmission.

  12. Acute skin lesions following psoralen plus ultraviolet A radiation investigated by optical coherence tomography (United States)

    Liu, Z. M.; Zhong, H. Q.; Zhai, J.; Wang, C. X.; Xiong, H. L.; Guo, Z. Y.


    Psoralen plus ultraviolet A radiation (PUVA) therapy is a very important clinical treatment of skin diseases such as vitiligo and psoriasis, but associated with an increased risk of skin photodamage, especially photoaging. In this work, optical coherence tomography (OCT), a novel non-invasive imaging technology, was introduced to investigate in vivo the photodamage induced by PUVA qualitatively and quantitatively. Balb/c mouse dorsal skin was treated with 8-methoxypsoralen (8-MOP), and then exposed to UVA radiation. OCT images of the tissues were obtained by an OCT system with a 1310 nm central wavelength. Skin thickness and the attenuation coefficient were extracted from the OCT images to analyze the degree of injury to mouse skin. The results demonstrated that PUVA-treated skin showed an increase in skin thickness, and a reduction of attenuation coefficient in the OCT signal compared with the control groups. The data also showed good correlation with the results observed in histological sections using hematoxylin and eosin staining. In conclusion, OCT is a promising tool for photobiological studies aimed at assessing the effect of PUVA therapy in vivo.

  13. Investigations on optical properties of Sm{sup 3+} ion doped boro-phosphate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Vijayakumar, R.; Suthanthirakumar, P.; Karthikeyan, P.; Marimuthu, K., E-mail: [Department of Physics, Gandhigram Rural Institute – Deemed University, Gandhigram – 624302 (India)


    The Sm{sup 3+} doped Boro-phosphate glasses with the chemical composition 60H{sub 3}BO{sub 3}+20Li{sub 2}CO{sub 3}+10ZnO+(10−x) H{sub 6}NO{sub 4}P+xSm{sub 2}O{sub 3} (where x= 0.1, 0.5, 1 and 2 in wt%) have been prepared by melt quenching technique. The prepared glasses were characterized through optical absorption and luminescence spectral measurements. The band gap energies corresponding to the direct and indirect allowed transitions and the Urbach’s energy values were estimated from the absorption spectra. Judd-Ofelt intensity parameters have been derived to predict the radiative properties of the various emission transitions. In order to identify the emission color of the prepared glasses, the emission intensities were analyzed using CIE 1931 color chromaticity diagram. The energy transfer process takes place between Sm{sup 3+}−Sm{sup 3+} ions through cross-relaxation mechanism have also been investigated and the results were discussed and reported.

  14. Structural and optical investigations of oxygen defects in zinc oxide nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Sahai, Anshuman; Goswami, Navendu, E-mail: [Department of Physics and Materials Science and Engineering, Jaypee Institute of Information Technology, A-10, Sec. 62, Noida. (U.P.)-201307 (India)


    ZnO nanoparticles (NPs) were prepared implementing chemical precipitation method. Structural and optical characterizations of synthesized ZnO NPs were thoroughly probed applying X-ray diffraction (XRD), transmission electron microscope (TEM), energy dispersive X-ray (EDX) analysis, X-ray photoelectron spectroscopy (XPS), UV- Visible absorption and fluorescence (FL) spectroscopy. The XRD and TEM analyses revealed hexagonal wurtzite phase with 25-30 nm size. EDX analysis indicated oxygen (O) rich composition of nanoparticles. In accordance with EDX, XPS analysis verifies O{sub i} rich stoichiometry of prepared NPs. Furthermore, concurrence of lattice oxygen (O{sub L}), interstitial oxygen (O{sub i}) and oxygen vacancy (V{sub O}) in ZnO NPs was demonstrated through XPS analysis. Size quantization of nanoparticles is evident by blue shift of UV-Visible absorption energy. The FL spectroscopic investigations ascertain the existence of several discrete and defect states and radiative transitions occurring therein. Display of visible emission from oxygen defect states and most importantly, excess of O{sub i} defects in prepared ZnO nanoparticles, was well established through FL study.

  15. Structural and optical investigations of oxygen defects in zinc oxide nanoparticles (United States)

    Sahai, Anshuman; Goswami, Navendu


    ZnO nanoparticles (NPs) were prepared implementing chemical precipitation method. Structural and optical characterizations of synthesized ZnO NPs were thoroughly probed applying X-ray diffraction (XRD), transmission electron microscope (TEM), energy dispersive X-ray (EDX) analysis, X-ray photoelectron spectroscopy (XPS), UV- Visible absorption and fluorescence (FL) spectroscopy. The XRD and TEM analyses revealed hexagonal wurtzite phase with 25-30 nm size. EDX analysis indicated oxygen (O) rich composition of nanoparticles. In accordance with EDX, XPS analysis verifies Oi rich stoichiometry of prepared NPs. Furthermore, concurrence of lattice oxygen (OL), interstitial oxygen (Oi) and oxygen vacancy (VO) in ZnO NPs was demonstrated through XPS analysis. Size quantization of nanoparticles is evident by blue shift of UV-Visible absorption energy. The FL spectroscopic investigations ascertain the existence of several discrete and defect states and radiative transitions occurring therein. Display of visible emission from oxygen defect states and most importantly, excess of Oi defects in prepared ZnO nanoparticles, was well established through FL study.

  16. Investigation of optical properties of anthocyanin doped into sol-gel based matrix (United States)

    Hashim, Hasrina; Abdul Aziz, Nik Mohd Azmi Nik; Isnin, Aishah


    Anthocyanin dye was extracted from petal of Hibiscus rosasinensis (Bunga Raya) and doped into sol-gel based matrix to investigate an effect of pH change on its optical properties. Sol-gel matrix based on Vinyl triethoxysilene (VTES) as a precursor was prepared through Sol-gel process at pH 7. The sol was doped with 0.1% of Anthocyanin and the same amount of dye was also dissolved in ethanol as a comparative sample. Hydrochloric Acid, HCl and Tetramethylammonium Hydroxide, TMAH were used to change the pH value by adding them at various concentrations into each sample. The emission spectra and chemical structures of the samples were measured by Spectrofluorometer and Fourier Transform Infrared (FTIR) respectively. When excited at 410 nm, two emission peaks at about 492 and 574 nm were observed for Anthocyanin in acidic environment both in ethanol and VTES sol. In base environment however, only Anthocyanin dissolved in ethanol produced emission peak with a single peak at about 539 nm. The sensitivity of Anthocyanin dye toward pH changes in VTES open a possibility to use it as sensing element in which sol-gel based matrix are known to have higher mechanical strength and thermal stability.

  17. Elaboration, structural and optical investigations of ZnO/epoxy nanocomposites (United States)

    Moussa, S.; Namouchi, F.; Guermazi, H.


    Hybrid nanocomposites were elaborated by incorporating ZnO nanoparticles into a transparent epoxy polymer matrix, using the direct dispersion method. The effect of the nanoparticles on the structural and optical properties of the polymer matrix was investigated using Fourier transform infrared (FTIR), Raman and UV-Visible spectroscopies. Nanocomposites FTIR spectra showed a variation of band intensities attributed to nanoparticles agglomeration within the polymer. The UV-Visible measurements showed a redshift on the band gap energy of the nanocomposites differently from neat epoxy resin, caused by interactions between ZnO NPs and polymer chains. Raman spectra confirm these interactions and the formation of hydrogen bonds in the nanocomposites. The UV-Visible transmittance spectra revealed that addition of a very low concentration (0.2wt%) of ZnO nanoparticles to a transparent epoxy matrix would maintain high visible-light transparency. The decrease of transmittance with increasing ZnO percentage is due to light scattering which originates from the agglomeration of nanoparticles in the matrix, the mismatch between the refractive index of ZnO and that of the epoxy matrix, and the increase of the surface roughness of the nanocomposite with increasing ZnO addition. Moreover, the UV-vis absorption spectra revealed that adding more than 1wt% ZnO leads to the improvement of the UV shielding properties of the nanocomposites. These results prove that the elaborated ZnO/epoxy nanocomposites can be used as UV shielding materials.

  18. Negative hemodynamic response without neuronal inhibition investigated by combining optical imaging and electrophysiological recording. (United States)

    Ma, Zengguang; Cao, Pengjia; Sun, Pengcheng; Lu, Zhuofan; Li, Liming; Chen, Yao; Chai, Xinyu


    Understanding the mechanisms underlying negative hemodynamic responses is critical for the interpretation of functional brain imaging signals. Negative imaging signals have been found in the visual, somatosensory and motor cortices in functional magnetic resonance imaging (fMRI) and intrinsic signal optical imaging (ISOI) studies. However, the origin of negative imaging signals is still controversial. The present study investigated the visual cortical responses to peripheral grating stimuli using multi-wavelength ISOI and electrophysiological recording. We found an increased cerebral blood volume (CBV) in the stimulus-induced regions and a decreased CBV in the adjacent regions in the visual cortex. Nevertheless, there was no significant change in blood oxygenation in the negative CBV regions. Furthermore, by combining the planar and laminar electrophysiological recordings, we did not observe significantly decreased neuronal activity in the negative CBV regions. Our results suggest that the negative hemodynamic response does not necessarily originate in decreased neuronal activity. Therefore, caution should be taken when interpreting a negative hemodynamic response as neuronal inhibition.

  19. Investigation of nonlinear optical (NLO) properties by charge transfer contributions of amine functionalized tetraphenylethylene (United States)

    Rana, Meenakshi; Singla, Nidhi; Chatterjee, Amrita; Shukla, Abhishek; Chowdhury, Papia


    Nonlinear Optical (NLO) properties of amine functionalized tetraphenylethylene (TPE-NH2) have been recorded and analyzed. The structural geometry, bonding features, harmonic vibrational frequencies (FTIR and Raman) of TPE-NH2 have been investigated by B3LYP density functional theory (DFT). Charge (Mulliken and natural) analysis, natural bond orbital (NBO) analysis, frontier molecular orbitals (FMOs), 13C and 1H nuclear magnetic resonance (NMR) and molecular electrostatic potential (MEP) indicate the delocalization of charges over the donor-acceptor region by the increase of C-N bond length. The vibrational analysis on the basis of potential energy distribution (PED) confirms the charge transfer interaction between donor and acceptor groups, and that in turn validates the presence of the larger dipole moment (μ), polarizability and hyperpolarizabilities (α, β and γ) in TPE-NH2. Higher value of ionization potential (IP), electronegativity (χ), hardness (η), chemical potential (CP) and smaller HOMO-LUMO energy gap (Δε) validate TPE-NH2's strong candidature to be used as an NLO active material.

  20. Investigation of retinal vessel autoregulation using real-time spectral domain Doppler optical coherence tomography (United States)

    Bower, Bradley A.; Zhao, Mingtao; Izatt, Joseph A.


    Investigation of the autoregulatory mechanism of human retinal perfusion was conducted with a novel real-time spectral domain Doppler optical coherence tomography (SDOCT) system. Volumetric, time-sequential, and Doppler flow imaging was performed in the superior arcade region on normal healthy subjects breathing normal room air and 100% oxygen. The real-time Doppler SDOCT system displays fully processed, high-resolution [512 (axial) x 1000 (lateral) pixels] B-scans at 17 frames/sec in volumetric and time-sequential imaging modes, and also displays fully processed overlaid color Doppler flow images comprising 512 (axial) x 500 (lateral) pixels at 6 frames/sec. OCT fundus images generated from volumetric datasets updated in real time (up to 2 fundus images/sec for 100 x 100 pixel volumes) were used to image and localize retinal vessels for time-sequential and Doppler flow analysis. In preliminary measurements, data acquired following 5 minutes of 100% oxygen inhalation was compared with that acquired 5 minutes post-inhalation. The same arterial segments examined at both time points exhibit constriction in vessel diameter under pure oxygen inhalation of up to 7% and reduction in peak flow velocity as great as 38%, both of which are in good agreement with previous laser Doppler velocimetry studies.

  1. Investigating the vortex melting phenomenon in BSCCO crystals using magneto-optical imaging technique

    Indian Academy of Sciences (India)

    A Soibel; S S Banerjee; Y Myasoedov; M L Rappaport; E Zeldov; S Ooi; T Tamegai


    Using a novel differential magneto-optical imaging technique we investigate the phenomenon of vortex lattice melting in crystals of Bi2Sr2CaCu2O8 (BSCCO). The images of melting reveal complex patterns in the formation and evolution of the vortex solid–liquid interface with varying field ()/temperature (). We believe that the complex melting patterns are due to a random distribution of material disorder/inhomogeneities across the sample, which create fluctuations in the local melting temperature or field value. To study the fluctuations in the local melting temperature/field, we have constructed maps of the melting landscape m(, ), viz., the melting temperature (m) at a given location () in the sample at a given field (). A study of these melting landscapes reveals an unexpected feature: the melting landscape is not fixed, but changes rather dramatically with varying field and temperature along the melting line. It is concluded that the changes in both the scale and shape of the landscape result from the competing contributions of different types of quenched disorder which have opposite effects on the local melting transition.

  2. Optical investigation of gold shell enhanced 25 nm diameter upconverted fluorescence emission (United States)

    Green, Kory; Wirth, Janina; Lim, Shuang Fang


    We enhance the efficiency of upconverting nanoparticles by investigating the plasmonic coupling of 25 nm diameter NaYF4:Yb, Er nanoparticles with a gold-shell coating, and study the physical mechanism of enhancement by single-particle, time-resolved spectroscopy. A three-fold overall increase in emission intensity, and five-fold increase of green emission for these plasmonically enhanced particles have been achieved. Using a combination of structural and fluorescent imaging, we demonstrate that fluorescence enhancement is based on the photonic properties of single, isolated particles. Time-resolved spectroscopy shows that the increase in fluorescence is coincident with decreased rise time, which we attribute to an enhanced absorption of infrared light and energy transfer from Yb3+ to Er3+ atoms. Time-resolved spectroscopy also shows that fluorescence life-times are decreased to different extents for red and green emission. This indicates that the rate of photon emission is not suppressed, as would be expected for a metallic cavity, but rather enhanced because the metal shell acts as an optical antenna, with differing efficiency at different wavelengths.

  3. Investigations on the electrical, thermal and optical properties of the nonlinear optical allylthiourea mercury chloride single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Sreekanth, G. [Department of Physics, St. Thomas College Pala, Kottayam 686574, Kerala (India); Chandralingam, S. [Department of Physics, Jawaharlal Nehru Technological University, Hyderabad 500085 (India); Philip, Jacob; Jayalakshmy, M.S. [Department of instrumentation, Cochin University of Science and Technology, Cochin, Kerala (India); Philip, Reji; Sridharan, Kishore [Raman research institute, Bangalore, Karnataka 560080 (India); Santhosh Kumar, R. [Department of Physics, St. George' s College Aruvithura, Kottayam 686122, Kerala (India); Joseph, Ginson P., E-mail: [Department of Physics, St. Thomas College Pala, Kottayam 686574, Kerala (India)


    Graphical abstract: Display Omitted Highlights: ► The single crystals of dimension 10 × 5 × 5 mm{sup 3} of allylthiourea mercury chloride are synthesized using slow evaporation technique. ► The bandgap of allylthiourea mercury chloride crystal is found to be about 3.18 eV. ► The optical nonlinearity of the crystal sample are studied using the open aperture Z-scan technique employing a nanosecond laser at 532 nm, and three photon absorption effect has been found. ► An improved photo pyroelectric is used to find the thermal parameters of the crystal. ► The piezoelectric charge coefficient is determined. -- Abstract: Single crystals of dimension 10 × 5 × 5 mm{sup 3} of allylthiourea mercury chloride were synthesized from aqueous solution using slow evaporation technique at ambient temperature. The grown crystals are confirmed by elemental analysis. The band gap of Allylthiourea mercury chloride crystal was found to be about 3.18 eV. The optical nonlinearity of the crystal sample was studied using the open aperture Z-scan technique employing a nanosecond laser at 532 nm, and a three-photon absorption effect has been found. The electrical properties such as dielectric constant, dielectric loss and ac conductivity of the sample were carried out by Agillent E 4980 A LCR meter at different temperatures. An improved photopyroelectric technique was used to find the thermal parameters of the crystal. The piezo electric charge coefficient is also determined.

  4. Thermodynamic investigations of the quasi-2d triangular Heisenberg antiferromagnet Cs{sub 2}CuCl{sub 2}Br{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Tutsch, Ulrich; Postulka, Lars; Wolf, Bernd; Lang, Michael; Well, Natalija van; Ritter, Franz; Krellner, Cornelius; Assmus, Wolf [Physikalisches Institut, Goethe-University Frankfurt (Germany)


    The system Cs{sub 2}CuCl{sub 4-x}Br{sub x} (0 ≤ x ≤ 4) is a quasi-two-dimensional Heisenberg antiferromagnet with a triangular in-plane arrangement of the spin-spin couplings. The ratio J{sup '}/J of the corresponding coupling constants determines the degree of frustration in the system and has been found to be 0.34 (x = 0) and 0.74 (x = 4) for the border compounds. One may ask whether for some intermediate Br concentration an even higher degree of frustration can be reached. Indeed, some indications have been reported by Ono et al. Here, we present specific heat C and susceptibility χ measurements below 1 K in magnetic fields B up to 13.5 T for the intermediate compound Cs{sub 2}CuCl{sub 2}Br{sub 2}, which, due to site-selective substitution, shows a well-ordered halide sublattice. Indications for an antiferromagnetic transition are observed around 90 mK for B = 0. A small field of B = 0.14 T is sufficient to fully suppress this anomaly. Taking into account the high saturation field of about 20 T, extrapolated from χ(T = const, B) scans at low temperatures, this small ordered region in the B-T plane clearly indicates a high degree of frustration in Cs{sub 2}CuCl{sub 2}Br{sub 2}.

  5. Investigation of optical nanostructures for photovoltaics with near-field scanning microscopy; Untersuchung optischer Nanostrukturen fuer die Photovoltaik mit Nahfeldmikroskopie

    Energy Technology Data Exchange (ETDEWEB)

    Beckers, Thomas


    Textured and rough surfaces are known to increase light trapping in solar cells significantly. The development and optimization of these nano-structures is essential to improve the energy conversion efficiency of thin-film solar cells. In the past, first research approaches covered classical and macroscopic investigations, e.g. determining the haze or angularly resolved scattering. These methods do not provide precise explanation for the optical improvement of the devices, because layer thicknesses and structure sizes in thin-film solar cells are smaller than the wavelength of visible light. The impact of local nano-structures and their contribution to the local absorption enhancement is not resolved by macroscopic measurements. In this thesis, near-field scanning optical microscopy is introduced as first near-field investigations of nano-structures for photovoltaics. This provides an insight into local optical effects for relevant surfaces of photovoltaic devices. Investigating the distribution of the electric fields in layer stacks is crucial to understand the absorption in solar cells. Evanescent fields, which occur due to total internal reflection at the interfaces, are measurable by near-field scanning optical microscopy and yield important information about local light trapping. Within the framework of this thesis, correlations between local surface structures and optical near-field effects are shown. In this case structure features of randomly textured surfaces, which optimize local light trapping, are identified. It paves the way to connect microscopic optical effects on the surface with the macroscopic performance of thin-film solar cells. Moreover, the measurement yields a 3D illustration of the electric field distribution over the sample surface. It is an important criterion to prove the results of rigorous diffraction theory. An excellent agreement between experiment and simulation is found. The simulations provide an insight into the material, which is

  6. Investigation of Surface Breakdown on Semiconductor Devices Using Optical Probing Techniques. (United States)


    18] L. Bovino , T. Burke, R. Youmans, M. Weiner, and J. Car, r, "Recent Advances in Optically C’ntrolled Bulk Semiconductor Switches," Digest of...Comp. Simul. 5 (3), 175 (1988). [321 M. Weiner, L. Bovino , R. Youmans, and T. Burke, "Modeling of the Optically Conrolled Semiconductor Switch," J

  7. Investigation of the effects of long-duration exposure on active optical system components (S0050) (United States)

    Blue, M. D.; Gallagher, J. J.; Shackelford, R. G.


    The effects of long duration space exposure on the relevant performance parameters of lasers, radiation detectors, and selected optical components, was determined. The results and implications of the measurements indicating real or suspected degradation mechanisms were evaluated and guidelines, based on these results, for selection and use of components for space electro-optical systems are established.

  8. Contributed Review: A review of the investigation of rare-earth dopant profiles in optical fibers (United States)

    Sidiroglou, F.; Roberts, A.; Baxter, G.


    Rare-earth doped optical fibers have captivated the interest of many researchers around the world across the past three decades. The growth of this research field has been stimulated primarily through their application in optical communications as fiber lasers and amplifiers, although rare-earth doped optical fiber based devices are now finding important uses in many other scientific and industrial areas (for example, medicine, sensing, the military, and material processing). Such wide commercial interest has provided a strong incentive for innovative fiber designs, alternative glass compositions, and novel fabrication processes. A prerequisite for the ongoing progress of this research field is developing the capacity to provide high resolution information about the rare-earth dopant distribution profiles within the optical fibers. This paper constitutes a comprehensive review of the imaging techniques that have been utilized in the analysis of the distribution of the rare-earth ion erbium within the core of optical fibers.

  9. Investigation of laser-surface interactions and optical damage mechanisms using excitation by pairs of picosecond laser pulses (United States)

    Chase, L. L.; Lee, H. W. H.; Hughes, Robert S.


    It is demonstrated that laser-surface interactions that cause optical surface damage of nominally transparent materials can be investigated by observing the effects of excitation by pairs of picosecond pulses separated by a variable time delay. Laser-induced emission of neutrals is used as the detection mechanism in the present experiments.

  10. Investigations of repetition rate stability of a mode-locked quantum dot semiconductor laser in an auxiliary optical fiber cavity

    DEFF Research Database (Denmark)

    Breuer, Stefan; Elsässer, Wolfgang; McInerney, J.G.


    We have investigated experimentally the pulse train (mode beating) stability of a monolithic mode-locked multi-section quantum-dot laser with an added passive auxiliary optical fiber cavity. Addition of the weakly coupled (¿ -24dB) cavity reduces the current-induced shift d¿/dI of the principal...

  11. Investigation on influence parameters in measurements of the optomechanical hole plate using an optical coordinate measuring machine

    DEFF Research Database (Denmark)

    Morace, Renate Erica; Hansen, Hans Nørgaard; De Chiffre, Leonardo;


    This paper describes the results of an experimental investigation on influence parameters in optical coordinate measurements of the optomechanical hole plate. Special attention was paid to the background of the object, which strongly influences the measurement result. Furthermore, it is seen...

  12. Linear and nonlinear optical investigations of nano-scale Si-doped ZnO thin films: spectroscopic approach (United States)

    Jilani, Asim; Abdel-wahab, M. Sh.; Zahran, H. Y.; Yahia, I. S.; Al-Ghamdi, Attieh A.


    Pure and Si-doped ZnO (SZO) thin films at different concentration of Si (1.9 and 2.4 wt%) were deposited on highly cleaned glass substrate by radio frequency (DC/RF) magnetron sputtering. The morphological and structural investigations have been performed by atomic force electron microscope (AFM) and X-ray diffraction (XRD). The X-ray photoelectron spectroscopy was employed to study the composition and the change in the chemical state of Si-doped ZnO thin films. The optical observations like transmittance, energy band gap, extinction coefficient, refractive index, dielectric loss of pure and Si-doped ZnO thin films have been calculated. The linear optical susceptibility, nonlinear refractive index, and nonlinear optical susceptibility were also studied by the spectroscopic approach rather than conventional Z-scan method. The energy gap of Si-doped ZnO thin films was found to increase as compared to pure ZnO thin films. The crystallinity of the ZnO thin films was effected by the Si doping. The O1s spectra in pure and Si-doped ZnO revealed the bound between O-2 and Zn+2 ions and reduction in the surface oxygen with the Si doping. The chemical state analysis of Si 2p showed the conversation of Si to SiOx and SiO2. The increase in the first-order linear optical susceptibility χ (1) and third-order nonlinear optical susceptibility χ (3) was observed with the Si doping. The nonlinear studies gave some details about the applications of metal oxides in nonlinear optical devices. In short, this study showed that Si doping through sputtering has effected on the structural, surface and optical properties of ZnO thin films which could be quite useful for advanced applications such as metal-oxide-based optical devices.

  13. A first-principles investigation of the optical spectra of oxidized graphene

    KAUST Repository

    Singh, Nirpendra


    The electronic and optical properties of mono, di, tri, and tetravacancies in graphene are studied in comparison to each other, using density functional theory. In addition, oxidized monovacancies are considered for different oxygen concentrations. Pristine graphene is found to be more absorptive than any defect configuration at low energy. We demonstrate characteristic differences in the optical spectra of the various defects for energies up to 3 eV. This makes it possible to quantify by optical spectroscopy the ratios of the defect species present in a sample.

  14. Investigation of the structural properties of an extended series of lanthanide bis-hydroxychlorides Ln(OH)(2)Cl (Ln = Nd-Lu, except Pm and Sm). (United States)

    Zehnder, Ralph A; Clark, David L; Scott, Brian L; Donohoe, Robert J; Palmer, Phillip D; Runde, Wolfgang H; Hobart, David E


    The trivalent lanthanide bis-hydroxychloride compounds, Ln(OH)(2)Cl, (Ln = Nd through Lu, with the exception of Pm and Sm) have been prepared by hydrothermal synthesis starting with LnCl(3).nH(2)O. These compounds were synthesized at temperatures not exceeding the melting point of the Teflon liners in the Parr autoclaves ( approximately 220 degrees C). The compounds obtained were characterized by single crystal X-ray diffraction analysis, diffuse reflectance, FT-IR, and FT-Raman spectroscopies. Most of the lanthanide(III) bis-hydroxychlorides are isostructural and generally crystallize in the monoclinic space group P2(1)/m. The bis-hydroxychlorides of the heavier lanthanide(III) atoms with smaller ionic radii also crystallize in the orthorhombic crystal system. Apparently hydrogen bonds between the OH groups and the Cl atoms connect the layers in the "c" direction. These H-bonds seem to be the driving force for the angle beta of the monoclinic complexes to decrease with decreasing ionic radius of the Ln(III) ion and also for tying the layers together more strongly. As a result of this behavior, the structure of the heavier 4f analogues significantly resembles that of their orthorhombic counterparts. The heavier lanthanide bis-hydroxychlorides preferentially crystallize in the orthorhombic modification. The IR absorbance and Raman frequencies of the hydroxide ligands correlate as a function of the central lanthanide(III) ionic radius. This observation is corroborated by X-ray diffraction (XRD) structural data. These compounds are quite insoluble in near-neutral and basic aqueous solutions, but soluble in acidic solutions. It is expected that the analogue actinide bis-hydroxychlorides exhibit similar behavior and that this may have important implications in the immobilization and safe disposal of nuclear waste.

  15. Structural, Wettability and Optical Investigation of Titanium Oxynitride Coatings: Effect of Various Sputtering Parameters

    Institute of Scientific and Technical Information of China (English)

    Sushant K Rawal; Amit Kumar Chawla; R: Jayaganthan; Ramesh Chandra


    The objective of the present work is to investigate the effect of various sputtering parameters such as nitrogen flow rate, deposition time and sputtering pressure on structural, wettability and optical properties of titanium oxynitride films deposited on glass substrate by reactive magnetron sputtering. The X-ray diffraction graphs of titanium oxynitride films show evolution of various textures of TiO=N and TiN phases with increasing nitrogen flow rate and deposition time, but an increase in sputtering pressure from 4.0 to 8.0 Pa results in decline of various textures observed for TiO=Ny and TiN phases. The stress and strain calculated by sin2~ method are compressive, which decrease with increasing nitrogen flow rate from 55 to I00 sccm (standard cubic centimeter per minute) and increase with increasing deposition time from 80 to I40 min due to atomic penning effect and increasing thickness of the deposited films. The titanium oxynitride films have contact angle values above 90 deg., indicating that films are hydrophobic. The maximum contact angle of I09.1 deg. is observed at deposition time of 140 min. This water repellent property can add value to potential protective, wear and corrosion resistant application of titanium oxynitride films. The band gap decreases from 1.98 to 1.83 eV as nitrogen flow rate is increased from 55 to 100 sccm; it decreases from 1.93 to 1.79 eV as deposition time is increased from 80 to 140 min as more nitrogen incorporation results in higher negative potential of valence band N2p orbital. But it increases from 2.26 to 2.34 eV for titanium oxynitride films as sputtering pressure increases from 4.0 to 8.0 Pa.

  16. Investigation into local cell mechanics by atomic force microscopy mapping and optical tweezer vertical indentation (United States)

    Coceano, G.; Yousafzai, M. S.; Ma, W.; Ndoye, F.; Venturelli, L.; Hussain, I.; Bonin, S.; Niemela, J.; Scoles, G.; Cojoc, D.; Ferrari, E.


    Investigating the mechanical properties of cells could reveal a potential source of label-free markers of cancer progression, based on measurable viscoelastic parameters. The Young’s modulus has proved to be the most thoroughly studied so far, however, even for the same cell type, the elastic modulus reported in different studies spans a wide range of values, mainly due to the application of different experimental conditions. This complicates the reliable use of elasticity for the mechanical phenotyping of cells. Here we combine two complementary techniques, atomic force microscopy (AFM) and optical tweezer microscopy (OTM), providing a comprehensive mechanical comparison of three human breast cell lines: normal myoepithelial (HBL-100), luminal breast cancer (MCF-7) and basal breast cancer (MDA-MB-231) cells. The elastic modulus was measured locally by AFM and OTM on single cells, using similar indentation approaches but different measurement parameters. Peak force tapping AFM was employed at nanonewton forces and high loading rates to draw a viscoelastic map of each cell and the results indicated that the region on top of the nucleus provided the most meaningful results. OTM was employed at those locations at piconewton forces and low loading rates, to measure the elastic modulus in a real elastic regime and rule out the contribution of viscous forces typical of AFM. When measured by either AFM or OTM, the cell lines’ elasticity trend was similar for the aggressive MDA-MB-231 cells, which were found to be significantly softer than the other two cell types in both measurements. However, when comparing HBL-100 and MCF-7 cells, we found significant differences only when using OTM.

  17. Investigation of anisoplanatic effect in adaptive optics for atmospheric turbulence correction (United States)

    Li, Xinyang; Shao, Li; Hu, Shijie; Huang, Kui


    Laser Guide Star (LGS) is an artificial atmospheric turbulence probing source of adaptive optics (AO) for compensating for the wave-front error of interested object in real time, and for providing approximate diffraction-limited resolution recovery. Actually the unavoidable anisoplanatic error resulting from different light experience between the LGS and the object of interest through turbulent atmosphere will lead to an incomplete wave-front distortion compensation of the object. In this paper the statistics of anisoplanatic errors and their associated Zernike-modal variances have been systematically investigated for different LGS sources by means of numerical simulation, including Rayleigh LGS and Sodium LGS. The numerical results show that the probed wave-front expanded Zernike-modal decorrelation versus angular deviation between the LGS and the object of interest becomes much more sensitive for the higher altitude LGS. For minor angular deviations with LGS focal spots being still within the ray path from the object to the telescope, the reduction of the error from turbulence above the LGS altitude is still a leading cause to decrease the residual error variance after AO correction. However, for the greater angular deviations with LGS focal spots moving on the outside of the ray path from the object to the telescope, higher-altitude LGS could lead to an increasing residual error variance after AO complete correction with its wave-front as reference. At this point the adopted LGS operation mode and the AO system modal correction optimization should be taken into account for achieving a desired residual wave-front error.

  18. Construction of force measuring optical tweezers instrumentation and investigations of biophysical properties of bacterial adhesion organelles

    CERN Document Server

    Andersson, Magnus


    Optical tweezers are a technique in which microscopic-sized particles, including living cells and bacteria, can be non-intrusively trapped with high accuracy solely using focused light. The technique has therefore become a powerful tool in the field of biophysics. Optical tweezers thereby provide outstanding manipulation possibilities of cells as well as semi-transparent materials, both non-invasively and non-destructively, in biological systems. In addition, optical tweezers can measure minute forces (< 10-12 N), probe molecular interactions and their energy landscapes, and apply both static and dynamic forces in biological systems in a controlled manner. The assessment of intermolecular forces with force measuring optical tweezers, and thereby the biomechanical structure of biological objects, has therefore considerably facilitated our understanding of interactions and structures of biological systems. Adhesive bacterial organelles, so called pili, mediate adhesion to host cells and are therefore crucial...

  19. Stress-induced birefringence in elastomers doped with ferrofluid magnetic particles: Mechanical and optical investigation

    Energy Technology Data Exchange (ETDEWEB)

    Sena, C. [Instituto de Fisica, Universidade de Sao Paulo, Caixa postal 66318, Sao Paulo, SP 05315-970 (Brazil); Bailey, C. [Liquid Crystal Institute, Kent State University, P.O. Box 5190, Kent, OH 44242-0001 (United States); Godinho, M.H. [Faculdade de Ciencias e Tecnologia e CENIMAT, Universidade Nova de Lisboa, Quinta da Torre, P-2829-516 Caparica (Portugal); Figueirinhas, J.L. [CFMC, Universidade de Lisboa, Avenida Prof. Gama Pinto 2, 1649 003 Lisbon (Portugal); Palffy-Muhoray, P. [Liquid Crystal Institute, Kent State University, P.O. Box 5190, Kent, OH 44242-0001 (United States); Figueiredo Neto, A.M. [Instituto de Fisica, Universidade de Sao Paulo, Caixa postal 66318, Sao Paulo, SP 05315-970 (Brazil)]. E-mail:


    Magnetic nanoparticles from magnetic colloidal suspensions were incorporated in the urethane/urea elastomer (PU/PBDO) by adding to the prepolymers solution in toluene diverse amounts of magnetite grains. It is shown that ferrofluid grains can be efficiently incorporated into the elastomer according to this procedure. Mechanical and optical experiments performed show that the elastomer preparation procedure (casting) introduces a structural anisotropy on the optically isotropic sample. This fact is put in evidence by the measurements of the Young's moduli and orientation of the sample's optical axis under stress. The dependence of the phase shift of both the pure and ferrofluid-doped elastomer samples under strain is linear, and the strain-optic coefficient is show to be linear with the ferrofluid concentration.

  20. Investigation on Characteristics and the Improving Method of Double Loop Optical Buffer

    Institute of Scientific and Technical Information of China (English)

    WANG Yong-Jun; WU Chong-Qing; WANG Zhi; YANG Shuang-Shou; ZHAO Shuang; WANG Ya-Ping; SHU Da; ZHAO Xi


    @@ We establish an equivalent cascaded semiconductor optical amplifier system model to analyze the characteristics of the double loop optical buffer (DLOB). The theoretical analysis finds that the performance of the DLOB can be improved by inserted amplifying process in an interval of some cycles. The experiment demonstrates that the buffered cycles can be improved from 20 to 50 and the bit error rate is less than 10-9 by inserting amplifying process in an interval of about 10 cycles.

  1. Investigating electro-optical properties of a nematic liquid crystal cell with planar anchoring boundary condition for various thicknesses: A Monte Carlo study (United States)

    Emül, Yakup; Polat, Ömer; San, Sait Eren; Kayacan, Özhan; Özbek, Haluk


    Monte Carlo (MC) simulations and the Mueller matrix formalism were applied to investigate electro optical properties of a LC cell with planar boundary conditions for various thicknesses. Field dependent global order parameter and the optical transmissions were analyzed in common. Three characteristic regions of the periodicity of optical transmissions as a function of polarizer angle and the external field were identified.

  2. Computational and in vivo investigation of optical reflectance from human brain to assist neurosurgery. (United States)

    Johns, M; Giller, C; Liu, H


    Parkinson's disease (PD) is a chronic, progressive disease involving the globus pallidus (GP), which is a gray matter mass, surrounded by white matter deep within the brain. During a neurosurgery procedure, a thin probe is inserted into the GP to create a lesion that often relieves the cardinal symptoms of PD. The goal of this study is to develop an optical method to accurately locate the GP border. In theory, Monte Carlo simulations were performed to predict the optical reflectance from brain tissue. In experiment, a portable, real-time display spectrometer with a fiber optic reflectance probe was developed and used during human surgery. Optical reflectance values were recorded at 1 mm intervals to obtain a spatial profile of the tissue as the probe passed through regions of gray and white matter. The simulation and in vivo studies of the reflectance from the brain are in good agreement with one another. The clinical data show that the reflectance from gray matter is approximately 50% or less than that from white matter between 650 and 800 nm. A slope algorithm is developed to distinguish gray and white matter in vivo. This study provides previously unknown optical reflectance of the human brain. © 1998 Society of Photo-Optical Instrumentation Engineers.

  3. Phosphorescence and zero-field optically detected magnetic resonance studies of (nd){sup 10} transition-metal complexes. 1. ZnX{sub 2}(phen) (X = Cl, Br, I)

    Energy Technology Data Exchange (ETDEWEB)

    Ikeda, Shigeru; Yamamoto, Seiichi; Azumi, Tohru [Tohoku Univ., Sendai (Japan)] [and others


    In order to elucidate the effect of (nd){sup 10} central metal ions on the properties of the low-lying excited states of metal complexes, spectroscopic and optically detected magnetic resonance studies on the phenanthroline (phen) localized {sup 3}{pi}{pi}* states of ZnX{sub 2}(phen) (X = Cl, Br, I) were carried out. Comparison of the properties of the spin sublevels of ZnX{sub 2}(phen) with those of the uncoordinated 1, 10-phenanthroline yielded several noteworthy features: (a) the phosphorescence spectra of ZnX{sub 2}(phen) complexes very closely resemble that of the uncoordinated phen molecule, (b) the magnitudes of the zero-field splittings follow the ordering phen > ZnCl{sub 2}(phen) replacing the z sublevel (in-plane component) as the dominant decay channel in uncoordinated phen. These experimental results have been interpreted systematically and satisfactorily by a model invoking Heitler-London type mixing of LLCT (halogen p-orbitals to phen charge transfer) electronic configurations with the phen locally excited electronic configuration. 31 refs., 4 figs., 7 tabs.

  4. Investigation of trace level binding of PtCl{sub 6} and PtCl{sub 4} to alfalfa biomass (Medicago sativa) using Zeeman graphite furnace atomic absorption spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Parsons, J.G.; Gardea-Torresdey, J.L.; Tiemann, K.J.; Gamez, G


    Batch laboratory experiments were performed to investigate the effects of pH, chemical modification, time dependency, and interference studies on the binding of trace concentrations of hexachloroplatinate(IV) and tetrachloroplatinate(II) to alfalfa biomass. The pH profiles were measured between pH 2.0 and 6.0. It was found that the binding of trace concentrations of platinum(IV and II) to alfalfa biomass was dependent on pH with a maximum binding occurring at pH 3.0 and a minimum at pH 6.0. When the alfalfa biomass was chemically modified (esterified), maximum binding occurred at pH 6.0 for both oxidation states of platinum. From the batch time dependency experiments, it was found that binding took at least 20 min to level off for both platinum oxidation states. Batch experiments were performed with various concentrations of calcium, magnesium, and sodium (0.1, 1.0, 10, 100 and 1000 ppm) and it was found that calcium affected the binding of platinum(II and IV) to the alfalfa biomass. It was determined that magnesium and sodium did not interfere appreciably with the binding of platinum in either of the oxidation states studied. Finally, batch experiments were performed with Mg{sup 2+}, Ca{sup 2+} and Na{sup +} in solutions at various concentrations, and it was observed that the binding was affected similarly to that by calcium alone.

  5. Investigation and Demonstration of High Speed Full-Optical Hybrid FSO/Fiber Communication System under Light Sand Storm Condition

    KAUST Repository

    Esmail, Maged Abdullah


    In contrast to traditional free space optical (FSO) systems, the new generation is aimed to be transparent to optical fiber where protocols, high signal bandwidths, and high data rates over fiber are all maintained. In this paper, we experimentally demonstrate a high speed outdoor full-optical FSO communication system over 100 m link. We first describe the design of our transmitter, which consists of a comb generator and a flexible multiformat transmitter. Our measurements are performed in arid desert area under a light dust storm. In this environment, we use a 12 subcarrier comb generator, each of which is modulated by a quadrature-amplitude modulation (QAM) signal. We achieved a 1.08 Tbps error free data rate with 3.6 b/s/Hz spectral efficiency. We place long optical fiber rolls in the transmitter side and the receiver side to mimic real FSO deployments. Furthermore, we investigated the effect of receiver misalignment in outdoor conditions and the effect of background noise. We find that full-optical FSO system is sensitive to the misalignment effect. However, the background noise has negligible effect. Finally, we find that solar heating of the transceiver causes collimator deviation, which requires using a cooling unit or auto tracking system.

  6. Optical lenses design and experimental investigations of a dynamic focusing unit for a CO2 laser scanning system (United States)

    Chen, Wei; Xu, Yue; Zhang, Huaxin; Liu, Peng; Jiao, Guohua


    Laser scanners are critical components in material processing systems, such as welding, cutting, and drilling. To achieve high-accuracy processing, the laser spot size should be small and uniform in the entire objective flat field. However, traditional static focusing method using F-theta objective lens is limited by the narrow flat field. To overcome these limitations, a dynamic focusing unit consisting of two lenses is presented in this paper. The dual-lens system has a movable plano-concave lens and a fixed convex lens. As the location of the movable optical elements is changed, the focal length is shifted to keep a small focus spot in a broad flat processing filed. The optical parameters of the two elements are theoretical analyzed. The spot size is calculated to obtain the relationship between the moving length of first lens and the shift focus length of the system. Also, the Zemax model of the optical system is built up to verify the theoretical design and optimize the optical parameter. The proposed lenses are manufactured and a test system is built up to investigate their performances. The experimental results show the spot size is smaller than 450um in all the 500*500mm 2 filed with CO2 laser. Compared with the other dynamic focusing units, this design has fewer lenses and no focusing spot in the optical path. In addition, the focal length minimal changes with the shit of incident laser beam.

  7. Investigating the impact of optical selection effects on observed rest frame prompt GRB properties

    CERN Document Server

    Turpin, Damien; Dezalay, Jean-Pascal; Atteia, Jean-Luc; Klotz, Alain; Dornic, Damien


    Measuring gamma-ray burst (GRB) properties in their rest-frame is crucial to understand the physics at work in gamma-ray bursts. This can only be done for GRBs with known redshift. Since redshifts are usually measured from the optical spectrum of the afterglow, correlations between prompt and afterglow emissions may introduce biases in the distribution of rest-frame properties of the prompt emission. Our analysis is based on a sample of 90 GRBs with good optical follow-up and well measured prompt emission. 76 of them have a measure of redshift and 14 have no redshift. We estimate their optical brightness with their R magnitude measured two hours after the trigger and compare the rest frame prompt properties of different classes of GRB afterglow brightness. We find that the optical brightness of GRBs in our sample is mainly driven by their intrinsic afterglow luminosity. We show that GRBs with low and high afterglow optical fluxes have similar Epi , Eiso , Liso , indicating that the rest-frame distributions co...

  8. Investigations of Optical Coherence Properties in an Erbium-doped Silicate Fiber for Quantum State Storage

    CERN Document Server

    Staudt, M U; Afzelius, M; Jaccard, D; Tittel, W; Gisin, Nicolas; Staudt, Matthias U.; Hastings-Simon, Sara R.; Afzelius, Mikael; Jaccard, Didier; Tittel, Wolfgang; Gisin, Nicolas


    We studied optical coherence properties of the 1.53 $\\mu$m telecommunication transition in an Er$^{3+}$-doped silicate optical fiber through spectral holeburning and photon echoes. We find decoherence times of up to 3.8 $\\mu$s at a magnetic field of 2.2 Tesla and a temperature of 150 mK. A strong magnetic-field dependent optical dephasing was observed and is believed to arise from an interaction between the electronic Er$^{3+}$ spin and the magnetic moment of tunneling modes in the glass. Furthermore, we observed fine-structure in the Erbium holeburning spectrum originating from superhyperfine interaction with $^{27}$Al host nuclei. Our results show that Er$^{3+}$-doped silicate fibers are promising material candidates for quantum state storage.

  9. Investigation of residual core ellipticity induced nonreciprocity in air-core photonic bandgap fiber optical gyroscope. (United States)

    Xu, Xiaobin; Zhang, Zuchen; Zhang, Zhihao; Jin, Jing; Song, Ningfang


    Air-core photonic bandgap fiber (PBF) is an excellent choice for fiber optic gyroscope owing to its incomparable adaptability of environment. Strong and continuous polarization mode coupling is found in PBFs with an average intensity of ~-30 dB, but the coupling arrives at the limit when the maximum optical path difference between the primary waves and the polarization-mode-coupling-induced secondary waves reaches ~10mm, which is corresponding to the PBF length of ~110 m according to the birefringence in the PBF. Incident light with the low extinction ratio (ER) can suppress the birth of the polarization-mode-coupling-induced secondary waves, but the low-ER light obtained by the conventional Lyot depolarizers does not work here. Consequently, a large nonreciprocity and a bias error of ~13°/h are caused in the air-core photonic bandgap fiber optical gyroscope (PBFOG) with a PBF coil of ~268 m.

  10. Investigation study on the nonlinear optical properties of natural dyes: Chlorophyll a and b (United States)

    Kouissa, B.; Bouchouit, K.; Abed, S.; Essaidi, Z.; Derkowska, B.; Sahraoui, B.


    We report the results on third and second order nonlinear optical susceptibilities of two natural pigments extracted from spinach. The last were identified by UV-vis spectral analysis. Thin films were prepared by spin coating technique and deposited on glass substrate. The measurements of third order nonlinear optical susceptibilities were performed in solutions using degenerate four wave mixing technique (DFWM) at the measurement wavelength of 532 nm. The third and second order nonlinear optical susceptibilities of the studied pigments were also evaluated on thin films using the third and second harmonics generation (THG and SHG) Maker fringes technique respectively at 1064 nm. All these results were in good agreement with the literature data.

  11. Electronic structure and optical properties of boron suboxide B6O system: First-principles investigations (United States)

    Wang, Jinjin; Wang, Zhanyu; Jing, Yueyue; Wang, Songyou; Chou, Che-Fu; Hu, Han; Chiou, Shan-Haw; Tsoo, Chia-Chin; Su, Wan-Sheng


    The structural, mechanical, electronic, and optical properties of B6O were explored by means of first-principles calculations. Such a system is mechanically stable and also a relatively hard material which are derived from obtained elastic constants and bulk moduli. Bulk B6O is a direct-gap semiconductor with a bandgap of about 2.93 eV within G0W0 approximation. Furthermore, the optical properties, such as real and imaginary parts of dielectric functions, refractive index and extinction coefficient, and the comparison of optical properties between the density-functional theory (DFT) and G0W0 Bethe-Salpeter equation (G0W0-BSE) results, were computed and discussed. The results obtained from our calculations open a possibility for expanding its use in device applications.

  12. Theoretical and experimental investigation of direct detection optical OFDM transmission using beat interference cancellation receiver. (United States)

    Nezamalhosseini, S Alireza; Chen, Lawrence R; Zhuge, Qunbi; Malekiha, Mahdi; Marvasti, Farokh; Plant, David V


    We theoretically and experimentally evaluate a beat interference cancellation receiver (BICR) for direct detection optical orthogonal frequency-division multiplexing (DD-OFDM) systems that improves the spectral efficiency (SE) by reducing the guard band between the optical carrier and the optical OFDM signal while mitigating the impact of signal-signal mixing interference (SSMI). Experimental results show that the bit-error-rate (BER) is improved by about three orders of magnitude compared to the conventional receiver after 320 km single-mode fiber (SMF) transmission for 10 Gb/s data with a 4-QAM modulation using reduced guard band single-sideband OFDM (RSSB-OFDM) signal with 1.67 bits/s/Hz SE.

  13. Diffuse optical intracluster light as a measure of stellar tidal stripping: the cluster CL0024+17 at $z\\sim $0.4 observed at LBT

    CERN Document Server

    Giallongo, E; Grazian, A; Gallozzi, S; Castellano, M; Fiore, F; Fontana, A; Pentericci, L; Boutsia, K; Paris, D; Speziali, R; Testa, V


    We have evaluated the diffuse intracluster light (ICL) in the central core of the galaxy cluster CL0024+17 at $z\\sim 0.4$ observed with the prime focus camera (LBC) at LBT. The measure required an accurate removal of the galaxies light within $\\sim 200$ kpc from the center. The residual background intensity has then been integrated in circular apertures to derive the average ICL intensity profile. The latter shows an approximate exponential decline as expected from theoretical cold dark matter models. The radial profile of the ICL over the galaxies intensity ratio (ICL fraction) is increasing with decreasing radius but near the cluster center it starts to bend and then decreases where the overlap of the halos of the brightest cluster galaxies becomes dominant. Theoretical expectations in a simplified CDM scenario show that the ICL fraction profile can be estimated from the stripped over galaxy stellar mass ratio in the cluster. It is possible to show that the latter quantity is almost independent of the prope...

  14. Investigating Tissue Optical Properties and Texture Descriptors of the Retina in Patients with Multiple Sclerosis.

    Directory of Open Access Journals (Sweden)

    Boglárka Enikő Varga

    Full Text Available To assess the differences in texture descriptors and optical properties of retinal tissue layers in patients with multiple sclerosis (MS and to evaluate their usefulness in the detection of neurodegenerative changes using optical coherence tomography (OCT image segmentation.38 patients with MS were examined using Stratus OCT. The raw macular OCT data were exported and processed using OCTRIMA software. The enrolled eyes were divided into two groups, based on the presence of optic neuritis (ON in the history (MSON+ group, n = 36 and MSON- group, n = 31. Data of 29 eyes of 24 healthy subjects (H were used as controls. A total of seven intraretinal layers were segmented and thickness as well as optical parameters such as contrast, fractal dimension, layer index and total reflectance were measured. Mixed-model ANOVA analysis was used for statistical comparisons.Significant thinning of the retinal nerve fiber layer (RNFL, ganglion cell/inner plexiform layer complex (GCL+IPL and ganglion cell complex (GCC, RNFL+GCL+IPL was observed between study groups in all comparisons. Significant difference was found in contrast in the RNFL, GCL+IPL, GCC, inner nuclear layer (INL and outer plexiform layer when comparing MSON+ to the other groups. Higher fractal dimension values were observed in GCL+IPL and INL layers when comparing H vs. MSON+ groups. A significant difference was found in layer index in the RNFL, GCL+IPL and GCC layers in all comparisons. A significant difference was observed in total reflectance in the RNFL, GCL+IPL and GCC layers between the three examination groups.Texture and optical properties of the retinal tissue undergo pronounced changes in MS even without optic neuritis. Our results may help to further improve the diagnostic efficacy of OCT in MS and neurodegeneration.

  15. Optical Orientation and Inverse Spin Hall Effect as Effective Tools to Investigate Spin-Dependent Diffusion

    Directory of Open Access Journals (Sweden)

    Marco Finazzi


    Full Text Available In this work we address optical orientation, a process consisting in the excitation of spin polarized electrons across the gap of a semiconductor. We show that the combination of optical orientation with spin-dependent scattering leading to the inverse spin-Hall effect, i.e., to the conversion of a spin current into an electrical signal, represents a powerful tool to generate and detect spin currents in solids. We consider a few examples where these two phenomena together allow addressing the spin-dependent transport properties across homogeneous samples or metal/semiconductor Schottky junctions.

  16. Experimental and theoretical investigations of absolute optical oscillator strengths for valence excitations of nitric oxide

    Institute of Scientific and Technical Information of China (English)

    朱林繁; 钟志萍; 苑震生; 张卫华; 刘小井; 江锡满; 徐克尊; 李家明


    The absolute optical oscillator strength density spectra of nitric oxide in the energy region of 5.0-22.0 eV havebeen measured by a high-resolution fast-electron energy loss spectrometer. With the calculated results obtained by themultiscattering self-consistent-field method and channel characteristics, the strongly overlapped spectra in the energyregion of 7.5-9.3 eV have been analysed and the corresponding partially vibrationally resolved optical oscillator strengthshave been estimated from the experimental spectra.

  17. Investigating the effects of capping layer on optical gain of nitride based semiconductor nanostructure lasers (United States)

    Annabi Milani, E.; Mohadesi, V.; Asgari, A.


    In this study, the effects of GaN capping layer on the behaviour of AlGaN/GaN nanostructure based laser is considered. We have employed the self-consistent solution of Poisson and Schrodinger equations for calculation of the energy levels, wave functions and conduction and valance bands profile. The impact of different thicknesses of the capping layer has been studied for sheet carrier density, then on optical gain. The results indicate that, by increasing the thickness of the cap layer, the optical gain decreases.

  18. Investigation on the Effect of the CdCl2 Treatment on CdTe Thin-film Solar Cells of Variable Thickness Fabricated Using Combinatorial Pulsed Laser Deposition (United States)

    Kadhim, Ali Saber

    Cadmium Chloride (CdCl2) post annealing process has significant impacts on the performance of the CdS/CdTe solar cells since it affects the microstructure, crystallinity and charge carrier doping in CdTe films and also the CdS/CdTe p-n junction formed through S and Te interdiffusion at the junction interface. Therefore, this process has been investigated extensively during the past two decades, and has been optimized for polycrystalline CdS/CdTe thick film solar cells, in which the CdTe thickness is typically in the range of 3-8 microm. Nevertheless, the recent effort to develop cost-performance balanced thin film CdS/CdTe solar cells (with CdTe thickness on the order of 1 microm or less) has encountered difficulties through direct applications of the thick-film CdCl2 post annealing process. These difficulties stem from the large CdTe grain sizes typically in the range of microns in the thick film case. Grain boundaries between such large grains result in through-thickness shorts when the CdTe film thickness is comparable to or smaller than the grain size. Overcoming these difficulties to achieve precise controls of grain morphology, crystallinity and CdS/CdTe interface is important to high-performance CdS/CdTe thin film solar cells and will be the main objective of this thesis. In order to accelerate the study, a combinatorial Pulsed Laser Deposition technique (cPLD) was developed for deposition of CdTe films with different thicknesses on each sample to elucidate important physical properties of Cl diffusion through the selected thickness range at a given CdCl 2 annealing condition. Two sets of samples A and B of CdTe solar cells of multiple thicknesses of 1.5, 1.25, 1.0, and 0.75 microm have been fabricated by using cPLD. Sample A was completed without CdCl2 treatment as a reference, and sample B was treated with CdCl2 in different durations (10, 12, 15, and 17 min) at 360°C in mixed vapor of O2 and Argon (25 sccm:100 sccm). The sample that was treated at 15

  19. Experimental Investigations of Transport and Optical Properties of 3-5 Quantum Well Structures Grown Via Molecular Beam Epitaxy under Optimal Growth Conditions (United States)


    Mariott Hotel , CA), SPIE Vol. 946, p.1 5 0 (1988). 13. W.C. Tang, Pudong Lao, and A. Madhukar, "Optical Investigation of Resonant Mixing Between...Superconductors; Physics and Device Applications", (13-18 March, 1988, Newport Beach Mariott Hotel , CA), SPIE Vol. 943, p.170 (1988). 14. F.J. Grunthaner...Newport Beach Mariott Hotel , CA). 4. W.C. Tang, Pudong Lao, and A. Madhukar, "Optical Investigation of Resonant Mixing Between Electronic and Optical

  20. An optical and theoretical investigation of the ultrafast dynamics of a bisthienylethene-based photochromic switch

    NARCIS (Netherlands)

    Hania, P.R.; Telesca, R.; Lucas, L.N.; Pugzlys, A; van Esch, J. H; Feringa, B.L.; Snijders, J.G.; Duppen, K.


    The switching behavior of 1,2-bis(5-phenyl-2-methylthien-3-yl)cyclopentene is studied by means of polarization selective nonlinear optical spectroscopy and time-dependent density functional theory. The combined information from the observed population and orientational dynamics together with the res

  1. Wide-Band Optical Fibre System for Investigation of MEMS and NEMS Deflection

    Directory of Open Access Journals (Sweden)

    Orłowska Karolina


    Full Text Available In this work the construction of experimental setup for MEMS/NEMS deflection measurements is presented. The system is based on intensity fibre optic detector for linear displacement sensing. Furthermore the electronic devices: current source for driving the light source and photodetector with wide-band preamplifier are presented.

  2. Computational and Theoretical Investigations of Strongly Correlated Fermions in Optical Lattices (United States)


    speaker, \\Physics of Superconductor - Insulator Transition and related topics", Argonne National Laboratory, November 16-19, 2010; talk titled \\Single...and two-particle spectral functions across the disorder- driven superconductor - insulator transition ". 22. Invited speaker, \\Fermions in gaps across the disorder- driven superconductor - insulator transition ", October 7, 2010, Harvard. 27. Seminar on \\Probing Quantum Phases of

  3. Investigation of optical currents in coherent and partially coherent vector fields

    DEFF Research Database (Denmark)

    Angelsky, O. V.; Gorsky, M. P.; Maksimyak, P. P.;


    in the arrangements of two-wave and four-wave superposition on the characteris-tics of the microparticle’s motion has been analyzed. The prospects of stud-ying temporal coherence using the proposed approach are made. For the first time, the possibility of diagnostics of optical currents in liquids caused...

  4. Investigation of a diode-pumped intracavity optical parametric oscillator in pulsed and continuous wave operation

    DEFF Research Database (Denmark)

    Jensen, Ole Bjarlin; Skettrup, Torben; Balle-Petersen, O.;


    Summary form only given. CW and pulsed compact tunable laser sources in the infrared have widespread scientific, medical and industrial applications. Such a laser source can be obtained by use of a diode-pumped intracavity optical parametric oscillator (IOPO). We report on a IOPO based on a Yb...

  5. Temperature-dependent interactions and disorder in the spin-transition compound [Fe(II)(L)2][ClO4]2.C7H8 through structural, calorimetric, magnetic, photomagnetic, and diffuse reflectance investigations. (United States)

    Mishra, Vibha; Mukherjee, Rabindranath; Linares, Jorge; Balde, Chérif; Desplanches, Cédric; Létard, Jean-François; Collet, Eric; Toupet, Loic; Castro, Miguel; Varret, François


    The title compound [Fe (II)(L) 2][ClO 4] 2.C 7H 8 (L = 2-[3-(2'-pyridyl)pyrazol-1-ylmethyl]pyridine) has been isolated while attempting to grow single crystals of the spin-transition (continuous-type) compound [Fe (II)(L) 2][ClO 4] 2, published earlier ( Dalton Trans. 2003, 3392-3397). Magnetic susceptibility measurements, as well as Mossbauer and calorimetric investigations on polycrystalline samples of [Fe(L) 2][ClO 4] 2.C 7H 8 revealed the occurrence of an abrupt HS ( (5) T 2) LS ( (1) A 1) transition with steep and narrow (2 K) hysteresis at approximately 232 K. The photomagnetic properties exhibit features typical for a broad distribution of activation energies, with relaxation curves in the shape of stretched exponentials. We performed a crystal structure determination of the compound at 120, 240, and 270 K. A noteworthy temperature-dependent behavior of the structural parameters was observed, in terms of disorder of both the anions and solvent molecules, leading to a strong thermal dependence of the strength and dimensionality of the interaction network. Additional data were obtained by diffuse reflectance measurements. We model and discuss the antagonistic effects of interactions and disorder by using a two-level cooperative mean-field approach which includes a distribution of barrier energies at the microscopic scale.

  6. Electronic State of Bismuth in BaBiO3 up to 9 Gpa Investigated by Optical Spectroscopy

    Institute of Scientific and Technical Information of China (English)

    刘晓峻; 守友浩


    Effects of hydrostatic pressure on the mixed-valence(MV)bismuth complex BaBiOa have been investigated up to ~9 GPa by means of high-pressure Raman scattering and absorption spectra at 300K.The pressure-induced hardening behaviour of the Bi-O stretching mode suggests that the predicted pressure-induced MV to the singlevalence(SV)phase change cannot occur.Investigation of absorption spectra with pressure shows the enhanced optical gap Egap,which further indicates the remained MV state of Bi ions.

  7. Investigation on the Optical and Surface Morphology of Conjugated Polymer MEH-PPV:ZnO Nanocomposite Thin Films


    Nurul Zayana Yahya; Mohamad Rusop


    Thin films of red color poly(2-methoxy-5(2′-ethylhexyloxy)-phenylene vinylene) (MEH-PPV) containing different weight percent of ZnO nanoparticles were obtained by spin-coating techniques. The MEH-PPV:ZnO solutions were spin coated onto silicon and glass substrates. The spun MEH-PPV:ZnO thin films were then used to investigate optical properties by using ultraviolet-visible spectrometer (UV-Vis) and photoluminescence spectrophotometer (PL). The morphologies were investigated by using field emi...

  8. Investigation on ultrafast third-order nonlinear optical properties of benzothiadiazole copolymer with triphenylamine derivative side chain (United States)

    Gong, Weixiang; Yang, Junyi; Qin, Yuan-cheng; Wu, Xing-zhi; Jin, Xiao; Song, Yinglin


    The third-order nonlinear optical properties of benzothiadiazole copolymer with triphenylamine derivative side chain (BCT) dissolved in chloroform are investigated by top-hat Z-scan and time-resolved pump-probe techniques with a picoseconds pulses laser at wavelength of 532nm. Organic polymers of triphenylamine have been widely applied to optoelectronic devices owing to its outstanding physics and chemistry characteristic. So its nonlinear optical characteristic is worth studying. The sample's excited-state dynamics can be detected by the pump-probe with phase object device with/without an aperture in the far field. We can determine the sample's nonlinear absorptive and refractive coefficient by the top-hot Z-scan device with/without an aperture in the far field. The experimental results show that the BCT has a good reverse saturation absorption and negative refraction. At the same time, the BCT showed up long excited-state lifetimes. By means of a five-level model and analyzing the experimental curves, all nonlinear optical parameters are obtained. With the proper lifetime and intersystem crossing time, this sample can be a candidate for optical limiting.

  9. Synthesis of MgO Nanoparticles by Solvent Mixed Spray Pyrolysis Technique for Optical Investigation

    Directory of Open Access Journals (Sweden)

    K. R. Nemade


    Full Text Available Solvent mixed spray pyrolysis technique has attracted a global interest in the synthesis of nanomaterials since reactions can be run in liquid state without further heating. Magnesium oxide (MgO is a category of the practical semiconductor metal oxides, which is extensively used as catalyst and optical material. In the present study, MgO nanoparticles were successfully synthesized using a solvent mixed spray pyrolysis. The X-ray diffraction pattern confirmed the formation of MgO phase with an excellent crystalline structure. Debye-Scherrer equation is used for the determination of particle size, which was found to be 9.2 nm. Tunneling electron microscope analysis indicated that the as-synthesized particles are nanoparticles with an average particle size of 9 nm. Meanwhile, the ultraviolet-visible spectroscopy of the resulting product was evaluated to study its optical property via measurement of the band gap energy value.

  10. Experimental Investigation on a Fibre-Optic Hydrophone with a Cylindrical Helmholtz Resonator

    Institute of Scientific and Technical Information of China (English)

    WANG Ze-Feng; HUNG Yong-Ming; MENG Zhou; NI Ming


    A novel mechanical anti-aliasing filtering fibre-optic hydrophone with a cylindrical Helmholtz resonator is constructed and tested.The experimental results show that the hydrophone has a function of low-pass filtering.The low frequency acoustic sensitivity is about -160 dB (1 rad/μPa),and the response curve has a resonance determined by the Helmholtz resonator.Theoretical and experimental results both show that the resonant frequency moves towards high frequency with the increasing orifice diameters.The sensitivity attenuation of high frequency is larger than 10 dB.This new fibre-optic hydrophone is a prototype device for a c/ass of sensors used to eliminate the aliasing in future sonar systems.

  11. The local structure and optical absorption characteristic investigation on Fe doped TiO2 nanoparticles

    CERN Document Server

    Zhao, Tianxing; Huang, Junheng; He, Jinfu; Liu, Qinghua; Pan, Zhiyun; Wu, Ziyu


    The local structures and optical absorption characteristic of Fe doped TiO2 nanoparticles synthesized by the sol-gel method were characterized by X-ray Diffraction (XRD), X-ray absorption fine structure spectroscopy (XAFS) and UV-Vis absorption spectroscopy (UV-Vis). XRD patterns show that all Fe-doped TiO2 samples have the characteristic anatase structure. Accurate Fe and Ti K-edge EXAFS analysis further reveal that all Fe atoms replace Ti atoms in the anatase lattice. The analysis of UV-Vis data shows a red shift to the visible range. According to the above results, we claim that substitutional Fe atoms lead to the formation of structural defects and new intermediate energy levels appear, narrowing the band gap and extending the optical absorption edge towards the visible region.

  12. Optical PIV and LDV Comparisons of Internal Flow Investigations in SHF Impeller

    Directory of Open Access Journals (Sweden)

    G. Wuibaut


    Full Text Available The paper presents a comparison between two sets of experimental results in a centrifugal flow pump. The tested impeller is the so-called SHF impeller for which many experimental data have been continuously produced to built databases for CFD code validations with various levels of approximation. Measurements have been performed using optical techniques: 2D particle image velocimetry (PIV technique on an air test model and 2D laser doppler velocimetry (LDV technique on a water model, both for different flow rates. For the present study, results obtained by these optical techniques are compared together in terms of phase averaged velocity and velocity fluctuations inside the impeller flow passage for design flow rate.

  13. Investigation on TCP/IP Congestion Control in Optical Burst Switched (OBS Network

    Directory of Open Access Journals (Sweden)

    Ms. Payal Daryani


    Full Text Available Transport Control Protocol (TCP is the dominant protocol in modern communication networks, in which the issues of reliability, flow, and congestion control must be handled efficiently. In this review paper an analytical switching is used to exploit the huge bandwidth of optical fibers for future high speed internet backbone. It carries multiple packets, in their turn. Different aggregation schemes have been considered and evaluated.TCP performance greatly depends on the TCP congestion window behavior that is related to loss events occurring in the optical burst switched network, there is a special term called traffic shaping by which we control over the network according to the network load .that means we increase or decrease the send rate according to the network demand.

  14. Femtosecond investigations of optical switching and χ(3) in GaAs waveguides (United States)

    LaGasse, Michael J.; Anderson, Kristin K.; Wang, Christine A.; Haus, Hermann A.; Fujimoto, James G.


    We describe a new technique for performing femtosecond transient measurements of nonlinear index and absorption in waveguide devices. Using a time division interferometry technique in conjunction with a tunable femtosecond laser source we have performed the first measurement of the wavelength dependent nonresonant nonlinear index in A1GaAs. Contributions to nonlinear index arise from both virtual as well as real population mediated processes depending on the wavelength detuning from resonance. Complementary pump-probe measurements of transient absorption provide information on excited state population as well as two-photon induced absorption processes. These measurements provide imformation on the mechanism and dynamics of fundamental nonlinear optical processes below the band edge in semiconductors and are relevant to possible all optical switching applications in waveguide devices.

  15. Optical investigations and absorption coefficient determination of InGaN/GaN quantum wells

    Energy Technology Data Exchange (ETDEWEB)

    Kvietkova, J.; Siozade, L.; Disseix, P.; Vasson, A.; Leymarie, J. [Clermont-Ferrand-2 Univ., 63 - Aubiere (France). CNRS, LASMEA, UMR 6602; Damilano, B.; Grandjean, N.; Massies, J. [CNRS, CRHEAS, Sophia Antipolis, Valbonne (France)


    Thermally detected optical absorption (TDOA) and photoluminescence experiments were carried out on InGaN/GaN multi-quantum well (MQW) structures grown by molecular beam epitaxy on (0001) sapphire substrates. The absorption coefficient of the QW was extracted by modelling the TDOA lineshape. These experimental findings are confronted with the theoretical optical density evaluated within envelope function calculations of transition energies and oscillator strengths, including the electric field effects. The results show a relative agreement obtained by using a smaller value of the electric field than it has been predicted theoretically. However, other effects must be included in our model in order to achieve a realistic description of the absorption process in this sophisticated system. (orig.)

  16. Pulsed Laser Deposited Nickel Doped Zinc Oxide Thin Films: Structural and Optical Investigations

    Directory of Open Access Journals (Sweden)

    Tanveer A. Dar


    Full Text Available Structural and optical studies has been done on Nickel doped Zinc Oxide (NixZn1 – xO, x  0.03, 0.05 and 0.07 by weight thin films prepared by pulsed laser deposition technique. The films are characterized by X-ray diffraction, Uv-vis spectroscopy, X-ray photoelectron spectroscopy. We observed a slight red shift in the optical band gap in the NiZnO subsequent to Ni doping. This shift can be assigned due to the sp-d exchange interaction of Ni- d states with s and p-states of ZnO. Also X-ray photoelectron spectroscopy studies show that Ni has well substituted in + 2 oxidation state by replacing Zn2+.

  17. DFT Investigation of Osmium Terpyridinyl Complexes as Potential Optical Limiting Materials

    CERN Document Server

    Alok, Shashwat


    The development of optical power limiting materials is important to protect individuals or materials from intense laser irradiation. The photophysical behavior of Os(II) polypyridinyl complexes having aromatic hydrocarbon terpyridyl ligands has received considerable attention as systems exhibiting intramolecular energy transfer to yield a long excited states lifetime. Here we present a focused discussion to illustrate the photophysical behavior of transition metal complexes with modified terpyridyl ligands, utilizing density functional theory. Our DFT studies of the excited state behavior of Os(II) complexes containing pyrene-vinylene derived terpyridine (pyr-v-tpy) ligands can be applied to the development of optical limiting materials controlling the laser power at longer wavelength range.

  18. Investigation of third-order nonlinear and optical power limiting properties of terphenyl derivatives (United States)

    Kamath, Laxminarayana; Manjunatha, K. B.; Shettigar, Seetharam; Umesh, G.; Narayana, B.; Samshuddin, S.; Sarojini, B. K.


    A series of new chalcones containing terphenyl as a core and with different functional groups has been successfully synthesized by Claisen-Schmidt condensation method in search of new nonlinear optical (NLO) materials. Molecular structural characterization for the compounds was achieved by FTIR and single crystal X-ray diffraction. The third-order NLO absorption and refraction coefficients were simultaneously determined by Z-scan technique. The measurements were performed at 532 nm with 7 ns laser pulses using a Nd:YAG laser in solution form. The Z-scan experiments reveal that the compounds exhibit strong nonlinear refraction coefficient of the order 10-11 esu and the molecular two photon absorption cross section is 10-46 cm4 s/photon. The results also show that the structures of the compounds have great impact on NLO properties. The compounds show optical power limiting behavior due to two-photon absorption (TPA).

  19. Fundamental Investigation of Jet Fuel Spray and Ignition Process in an Optically Accessible Piston Engine (United States)


    design of Almy engines . Tests were perf01med using #2 diesel fuel, jet fuel (JP8), and a hydroprocessed renewable jet fuel (HRJ). Ambient the1modynamic...1+~ .,:-•. ~-~ ~~~~·~~· · -~ ~- --~~ 1S. SUBJECT TERMS Transient, diesel , injection, optical engine 16. SECURITY...injection process in small bore diesel engines . (a) Papers published in peer-reviewed journals (N/A for none) Enter List of papers submitted or

  20. Development and use of compact instruments for tropospheric investigations based on optical spectroscopy from mobile platforms


    Merlaud, Alexis


    This thesis presents the development of four different remote-sensing instruments dedicated to atmospheric research and their use in field campaigns between 2008 and 2012. The instruments are based on uv-visible spectrometers and installed respectively on a scientific aircraft (Safire ATR-42), ultralight aircraft, and cars. One of the instruments is targeted to operate from an Unmanned Aerial Vehicle (UAV). The Differential Optical Absorption Spectroscopy (DOAS) technique is used to quantify ...

  1. Investigation of Metastatic Breast Tumor Heterogeneity and Progression Using Dual Optical/SPECT Imaging. Addendum (United States)


    an 18 gauge hypodermic needle was inserted. There are five different radial positions for the needle rang- ing from the center to just below the...surface, with step size of 2.54 mm. The light is emitted from the tapered end of the optical fiber 1 mm in size which was threaded through the needle ;41...light propagation in highly scattering tissues. I. Model predictions and comparison with diffusion theory ,” IEEE Trans. Biol. Eng. 36, 1162–1168 1989

  2. Spectroscopic ellipsometry investigations of the optical properties of manganese doped bismuth vanadate thin films

    Energy Technology Data Exchange (ETDEWEB)

    Kumari, Neelam; Krupanidhi, S.B. [Materials Research Center, Indian Institute of Science, Bangalore 560012 (India); Varma, K.B.R., E-mail: [Materials Research Center, Indian Institute of Science, Bangalore 560012 (India)


    The optical properties of Bi{sub 2}V{sub 1-x}Mn{sub x}O{sub 5.5-x} {l_brace}x = 0.05, 0.1, 0.15 and 0.2 at.%{r_brace} thin films fabricated by pulsed laser deposition on platinized silicon substrates were studied in UV-visible spectral region (1.51-4.17 eV) using spectroscopic ellipsometry. The optical constants and thicknesses of these films have been obtained by fitting the ellipsometric data ({Psi} and {Delta}) using a multilayer four-phase model system and a relaxed Lorentz oscillator dispersion relation. The surface roughness and film thickness obtained by spectroscopic ellipsometry were found to be consistent with the results obtained by atomic force and scanning electron microscopy. The refractive index measured at 650 nm does not show any marginal increase with Mn content. Further, the extinction coefficient does not show much decrease with increasing Mn content. An increase in optical band gap energy from 2.52 to 2.77 eV with increasing Mn content from x = 0.05 to 0.15 was attributed to the increase in oxygen ion vacancy disorder.

  3. An investigation for the development of an integrated optical data preprocessor. [preprocessing remote sensor outputs (United States)

    Verber, C. M.; Kenan, R. P.; Hartman, N. F.; Chapman, C. M.


    A laboratory model of a 16 channel integrated optical data preprocessor was fabricated and tested in response to a need for a device to evaluate the outputs of a set of remote sensors. It does this by accepting the outputs of these sensors, in parallel, as the components of a multidimensional vector descriptive of the data and comparing this vector to one or more reference vectors which are used to classify the data set. The comparison is performed by taking the difference between the signal and reference vectors. The preprocessor is wholly integrated upon the surface of a LiNbO3 single crystal with the exceptions of the source and the detector. He-Ne laser light is coupled in and out of the waveguide by prism couplers. The integrated optical circuit consists of a titanium infused waveguide pattern, electrode structures and grating beam splitters. The waveguide and electrode patterns, by virtue of their complexity, make the vector subtraction device the most complex integrated optical structure fabricated to date.

  4. Investigation of Electrical and Optical Properties of Highly Transparent TCO/Ag/TCO Multilayer. (United States)

    Kim, Sunbo; Lee, Jaehyeong; Dao, Vinh Ai; Ahn, Shihyun; Hussain, Shahzada Qamar; Park, Jinjoo; Jung, Junhee; Lee, Chan; Song, Bong-Shik; Choi, Byoungdeog; Lee, Youn-Jung; Iftiquar, S M; Yi, Junsin


    Transparent conductive oxides (TCOs) have been widely used as transparent electrodes for opto-electronic devices, such as solar cells, flat-panel displays, and light-emitting diodes, because of their unique characteristics of high optical transmittance and low electrical resistivity. Among various TCO materials, zinc oxide based films have recently received much attention because they have advantages over commonly used indium and tin-based oxide films. Most TCO films, however, exhibit valleys of transmittance in the wavelength range of 550-700 nm, lowering the average transmittance in the visible region and decreasing short-circuit current (Isc) of solar cells. A TCO/Ag/TCO multi-layer structure has emerged as an attractive alternative because it provides optical characteristics without the valley of transmittance compared with a 100-nm-thick single-layer TCO. In this article, we report the electrical, optical and surface properties of TCO/Ag/TCO. These multi-layers were deposited at room temperature with various Ag film thicknesses from 5 to 15 nm while the thickness of TCO thin film was fixed at 40 nm. The TCO/Ag/TCO multi-layer with a 10-nm-thick Ag film showed optimum transmittance in the visible (400-800 nm) wavelength region. These multi-layer structures have advantages over TCO layers of the same thickness.

  5. Morphological and optical investigation of Sol-Gel ZnO films (United States)

    Ivanova, T.; Harizanova, A.; Petrova, A.


    This paper presents morphological and optical studies of the properties of spin-coated ZnO films depending on the annealing temperatures. The films microstructure was explored using a scanning nano-hardness measuring device of the NanoScan family, based on the principles of atomic force microscopy, in a constant frequency mode. The surface study revealed that the root-mean-square (RMS) surface roughness of 985.64×985.64 nm ZnO films becomes greater with the increase of the annealing temperature, but the film surface remains uniform and smooth. The results were confirmed by XRD analysis, which demonstrated that the crystallite size grew from 25 to 36 nm with the thermal treatments. The ZnO films possessed high transmittance in the visible spectral range and the optical band gaps in ZnO films varied from 3.25 eV to 3.52 eV. The optical and morphological properties of the ZnO films formed on Si and quartz substrates are very good. The sol-gel approach proposed for deposition of nanostructured ZnO films is promising for applications in optoelectronic devices or solar cells.

  6. Investigating microstructural evolution during the electroreduction of UO2 to U in LiCl-KCl eutectic using focused ion beam tomography (United States)

    Brown, L. D.; Abdulaziz, R.; Tjaden, B.; Inman, D.; Brett, D. J. L.; Shearing, P. R.


    Reprocessing of spent nuclear fuels using molten salt media is an attractive alternative to liquid-liquid extraction techniques. Pyroelectrochemical processing utilizes direct, selective, electrochemical reduction of uranium dioxide, followed by selective electroplating of a uranium metal. Thermodynamic prediction of the electrochemical reduction of UO2 to U in LiCl-KCl eutectic has shown to be a function of the oxide ion activity. The pO2- of the salt may be affected by the microstructure of the UO2 electrode. A uranium dioxide filled "micro-bucket" electrode has been partially electroreduced to uranium metal in molten lithium chloride-potassium chloride eutectic. This partial electroreduction resulted in two distinct microstructures: a dense UO2 and a porous U metal structure were characterised by energy dispersive X-ray spectroscopy. Focused ion beam tomography was performed on five regions of this electrode which revealed an overall porosity ranging from 17.36% at the outer edge to 3.91% towards the centre, commensurate with the expected extent of reaction in each location. The pore connectivity was also seen to reduce from 88.32% to 17.86% in the same regions and the tortuosity through the sample was modelled along the axis of propagation of the electroreduction, which was seen to increase from a value of 4.42 to a value of infinity (disconnected pores). These microstructural characteristics could impede the transport of O2- ions resulting in a change in the local pO2- which could result in the inability to perform the electroreduction.

  7. Quantum chemical study of chlorine-dissociation of oxalyl chloride (ClCO)2→2Cl + 2CO

    Institute of Scientific and Technical Information of China (English)

    DAI; Nianzhen; (戴年珍); LI; Zonghe; (李宗和)


    The multi-bond dissociation dynamics of oxalyl chloride ((ClCO)2) is investigated by ab initio calculation. Dissociation of C-Cl bond of oxalyl chloride in the ground state is of barrierless. After the absorption of a photon, (ClCO)2 is excited to the first excited state and one of its C-Cl bonds is broken toyield Cl and ClCOCO* free radicals. In addition, ClCOCO* with high energy is prone to release energy (Q), and to turn into ClCOCO in the ground state. The energy (Q) is adequate for ClCOCO to break down into ClCO and CO, and even for ClCO into Cl and CO. The result is consistent with the experimental data that Kong reported.

  8. Investigation of electrical and optical properties of MEH-PPV: ZnO nanocomposite films for OLED applications (United States)

    Azhar, N. E. A.; Shafura, A. K.; Affendi, I. H. H.; Shariffudin, S. S.; Saurdi, I.; Alrokayan, Salman A. H.; Khan, Haseeb A.; Rusop, M.


    Recent investigations of the promising materials for optoelectronic have been demonstrated by introducing n-type inorganic material into conjugated polymer. The optical and electrical of nanocomposite films based on poly[2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV) and zinc oxide (ZnO) nanostructured of various deposition layers (1 to 3 layers) have been investigated. The MEH-PPV: ZnO nanocomposite films were deposited using spin-coating technique. The surface morphology nanocomposite films were characterized using field emission scanning electron microscope. From surface profiler measurement, we found that the thickness of nanocomposite films increased as deposition time increased. The optical properties were measured using photoluminescence spectroscope. The photoluminescence (PL) spectra showed that two deposition layers is the highest intensity at visible region (green emission) due to high energy transfer from particles to the polymer. The current density for two layers sample is due to aggregation of conjugated polymer chain hence form excited interchain exciton for optical excitation. This study will provide better performance and suitable for optoelectronic device especially OLEDs application.

  9. Investigating the nature of the Fried Egg nebula: CO mm-line and optical spectroscopy of IRAS 17163-3907

    CERN Document Server

    Wallström, Sofia H J; Lagadec, E; Black, J H; Oudmaijer, R D; Justtanont, K; van Winckel, H; Zijlstra, A A


    Through CO mm-line and optical spectroscopy, we investigate the properties of the Fried Egg nebula IRAS 17163-3907, which has recently been proposed to be one of the rare members of the yellow hypergiant class. The CO J=2-1 and J=3-2 emission arises from a region within 20" of the star and is clearly associated with the circumstellar material. The CO lines show a multi-component asymmetrical profile, and an unexpected velocity gradient is resolved in the east-west direction, suggesting a bipolar outflow. This is in contrast with the apparent symmetry of the dust envelope as observed in the infrared. The optical spectrum of IRAS 17163-3907 between 5100 and 9000 {\\AA} was compared with that of the archetypal yellow hypergiant IRC+10420 and was found to be very similar. These results build on previous evidence that IRAS 17163-3907 is a yellow hypergiant.

  10. Tip-enhanced Raman spectroscopy with silver-coated optical fiber probe in reflection mode for investigating multiwall carbon nanotubes. (United States)

    Wang, Rui; Wang, Jia; Hao, Fenghuan; Zhang, Mingqian; Tian, Qian


    We developed a tip-enhanced Raman spectrometer (TERS) with reflection mode. The instrument, with a scanning shear-force microscope (ShFM) and a side-illumination Raman spectroscope, can overcome the diffraction limit and has high sensitivity. A chemical method to fabricate optical fiber probes with Ag coating is proposed. The local electromagnetic responses of the silver-coated optical fiber probe are numerically analyzed by the finite-difference time-domain method, and the excitation wavelength is optimized to resonate with the localized surface plasmons (LSP) of the probe tip. The instrument is applied to investigate a single multiwall carbon nanotube. The experiment results indicate that our TERS instrument has a spatial resolution better than 70 nm, and the enhancement factor is about 5 x 10(3).

  11. Investigations on electronic, Fermi surface, Curie temperature and optical properties of Zr2CoAl (United States)

    Wei, Xiao-Ping; Sun, Weiwei; Zhang, Ya-Ling; Sun, Xiao-Wei; Song, Ting; Wang, Ting; Zhang, Jia-Liang; Su, Hao; Deng, Jian-Bo; Zhu, Xing-Feng


    Using full-potential local-orbital minimum-basis along with spin-polarized relativistic Korringa-Kohn-Rostoker methods, we study the electronic, Fermi surface, Curie temperature and optical properties of Zr2CoAl alloy. The alloy with Li2AgSb and Cu2MnAl structures are compared in terms of magnetic properties, and the electronic structures in two structures are also discussed. According to the calculated electronic states, it finds that the Zr2CoAl with Li2AgSb structure is half-metallic ferromagnet with an integral magnetic moment of 2.00μB , meanwhile we also notice the d-d and p-d hybridizations are responsible for the formation of minority-spin gap, furthermore, the fat-bands are applied to discuss the mixture between d and p electrons in the vicinity of the Fermi level. The Fermi surfaces related to the valence bands are constructed, and it is found that the spin-up valence bands 26, 27 and 28 across the Fermi energy dominate the nature of electrons. By mapping the system onto a Heisenberg Hamiltonian, we obtain the exchange coupling parameters, and observe that the Zr(A)-Co(C) and Zr(A)-Zr(B) interactions provide a major contribution for exchange interactions. Based on the calculated exchange coupling parameters, the Curie temperature is estimated to be 287.86 K at equilibrium, and also the dependence of Curie temperature on lattice constant related to the tunable Curie temperature in Zr2CoAl alloy is studied. Finally, we report the optical properties of Zr2CoAl alloy, and present the photon energy dependence of the absorption, the optical conductivity and the loss function.

  12. Investigation on a fiber optic accelerometer based on FBG-FP interferometer (United States)

    Lin, Chongyu; Luo, Hong; Xiong, Shuidong; Li, Haitao


    A fiber optic accelerometer based on fiber Bragg grating Fabry-Perot (FBG-FP) interferometer is presented. The sensor is a FBG-FP cavity which is formed with two weak fiber Bragg gratings (FBGs) in a single-mode fiber. The reflectivity of the two FBGs is 9.42% and 7.74% respectively, and the fiber between them is 10 meters long. An optical demodulation system was set up to analyze the reflected light of FBG-FP cavity. Acceleration signals of different frequencies and intensities were demodulated correctly and stably by the system. Based on analyzing the optical spectrum of weak FBG based FBG-FP cavity, we got the equivalent length of FBG-FP cavity. We used a path-matching Michelson interferometer (MI) to demodulate the acceleration signal. The visibility of the interference fringe we got was 41%~42% while the theory limit was 50%. This indicated that the difference of interferometer's two arms and the equivalent length of FBG-FP cavity were matched well. Phase generated carrier (PGC) technology was used to eliminate phase fading caused by random phase shift and Faraday rotation mirrors (FRMs) were used to eliminate polarization-induced phase fading. The accelerometer used a compliant cylinder design and its' sensitivity and frequency response were analyzed and simulated based on elastic mechanics. Experiment result showed that the accelerometer had a flat frequency response over the frequency range of 31-630Hz. The sensitivity was about 31dB (0dB=1rad/g) with fluctuation less than 1.5dB.

  13. Ag clustering investigation in laser irradiated ion-exchanged glasses by optical and vibrational spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Trave, E., E-mail: [Department of Molecular Sciences and Nanosystems, Ca' Foscari University of Venezia, Dorsoduro 2137, I-30123 Venezia (Italy); Cattaruzza, E.; Gonella, F.; Calvelli, P. [Department of Molecular Sciences and Nanosystems, Ca' Foscari University of Venezia, Dorsoduro 2137, I-30123 Venezia (Italy); Quaranta, A. [Department of Materials Engineering and Industrial Technologies, University of Trento, via Mesiano 77, I-38050 Povo (Italy); Rahman, A.; Mariotto, G. [Department of Computer Science, University of Verona, Strada le Grazie 15, 37134 Verona (Italy)


    Highlights: Black-Right-Pointing-Pointer We modify the properties of Ag{sup +} exchanged glasses by thermal and laser treatment. Black-Right-Pointing-Pointer The induced microstructural changes are analyzed by optical and Raman spectroscopy. Black-Right-Pointing-Pointer Ag-based species in the glass show a peculiar PL activity in the UV-Vis range. Black-Right-Pointing-Pointer Raman and OA analysis allow for determining the Ag cluster size evolution. Black-Right-Pointing-Pointer Laser processing leads to different cluster formation and fragmentation mechanisms. - Abstract: Ion exchange process is widely used to dope silicate glass layers with silver for several applications, ranging from light waveguide to nanostructured composite glass fabrication. The silver-doped structure and its physical properties depend on the preparation parameters as well as on subsequent treatments. In particular, laser irradiation of the ion exchanged glasses has been demonstrated to be an effective tool to control cluster size and size distribution. Nevertheless, a complete comprehension of the basic phenomena and a systematic characterization of these systems are still lacking. In this paper, an extended optical characterization is presented for soda-lime glass slides, doped with silver by Ag{sup +}-Na{sup +} ion exchange, thermally treated and irradiated with a Nd:YAG laser beam at different wavelengths, and for different energy density. The samples were characterized by various spectroscopic techniques, namely, optical absorption, photoluminescence and micro-Raman analysis. The availability of all these characterization techniques allowed pointing out a suitable scenario for the Ag clustering evolution as a function of the ion exchange, annealing and laser irradiation parameters.

  14. Investigation of ultracold atoms and molecules in a dark magneto-optical trap

    Institute of Scientific and Technical Information of China (English)

    Wang Li-Rong; Ji Zhong-Hua; Yuan Jin-Peng; Yang Yan; Zhao Yan-Ting; Ma Jie; Xiao Lian-Tuan; Jia Suo-Tang


    In this paper,ultracold atoms and molecules in a dark magneto-optical trap (MOT) are studied via depumping the cesium cold atoms into the dark hyperfine ground state.The collision rate is reduced to 0.45 s-1 and the density of the atoms is increased to 5.6 × 1011 cm-3 when the fractional population of the atoms in the bright hyperfine ground state is as low as 0.15.The vibrational spectra of the ultracold cesium molecules are also studied in a standard MOT and in a dark MOT separately.The experimental results are analyzed by using the perturbative quantum approach.

  15. Investigation on bismuth-oxide photonic crystal fiber for optical parametric amplification

    Institute of Scientific and Technical Information of China (English)

    JIN Cang; RAO Lan; YUAN Jin-hui; SHEN Xiang-wei; YU Chong-xiu


    A hexagonal solid-core bismuth-oxide micro-structure fiber is developed to balance its dispersion and nonlinearity. This simulation and calculation results show that the bismuth-oxide photonic crystal fiber (Bi-PCF) has near zero dispersion around 1550 nm. Its dispersion slop in the communication wavelength range is also relatively flat. Moreover, both nonlinear coefficient and model field distribution are obtained. Compared with the experimental results by SiO-PCF, it can be seen that the Bi-PCF shows excellent characteristics for the optical parametric amplification (OPA).

  16. Investigations of intensity dependant nonlinear optical properties of betanin/ZnO composites embedded in PVA (United States)

    Thankappan, Aparna; Nampoori, V. P. N.; Thomas, Sabu


    In this report, we report the intensity dependant nonlinear absorption properties of bio-inspired hybrid materials (betanin-ZnO) embedded in polymeric matrices through the Z-scan technique using an Nd: YAG laser (532 nm, 7 ns, 10 Hz). We observed a change over in the sign of nonlinearity due to the interplay of exciton bleaching and optical limiting mechanisms. Light confinement effect and ship-in-a bottle effect play crucial roles. Theoretical analysis has been performed using a model based on nonlinear absorption coefficient and saturation intensity. The result of present study gives an additional mechanism for the gain enhancement in dye doped ZnO matrix.

  17. An Optical and Computational Investigation on the Effects of Transient Fuel Injections in Internal Combustion Engines (United States)

    Neal, Nicholas

    The effects of transient rate-of-injection profiles on high-pressure fuel jets have been studied in an optically accessible internal combustion engine. High-speed optical imaging measurements were applied over a range of ambient conditions, fuel types, and injection parameters. The optical data demonstrate that during the early part of the injection, while the liquid core of the jet is disintegrating, penetration is functionally linked to the orifice exit velocity up until a downstream distance hypothesized to be the jet breakup length. The jets then transition to a mixing dominated penetration behavior further downstream. Therefore, for cases that exhibit transient rate-of-injection (ROI) profiles, quasi-steady correlations for penetration have poor agreement with the empirical data. The lack of agreement between models using quasi-steady approximations and the high-speed experimental data, and the experimental evidence of liquid core physics impacting the transient jet penetration, motivated the development of a new 1-D model that integrates liquid core penetration physics and eliminates quasi-steady approximations. The new 1-D modeling methodology couples the transport equations for the evolution of the liquid core of the jet and the surrounding sheath of droplets resulting from breakup. The results of the model are validated against the aforementioned optical transient jet measurements. Finally, experimental results for two jet fuels and a diesel fuel are studied with the aid of the model. Differences in fuel properties cause the diesel fuel jet to transition from an incomplete spray to a complete spray later than the jet fuels during the transient injection process. Increasing ambient density causes the transition to happen earlier during the injection transient for all three fuels. The ignition delay and liftoff length appeared to be relatively unaffected by the late transition from incomplete to complete spray at low ambient density and low injection

  18. First-Principles Investigations of the Phase Transition and Optical Properties of Solid Oxygen

    Institute of Scientific and Technical Information of China (English)

    LIU Yan-Hui; DUAN De-Fang; WANG Lian-Cheng; ZHU Chun-Ye; CUI Tian


    @@ Using density-functional-theory calculations,a monoclinic metallic post-ζ phase(space group C2/c)is predicted at 215 GPa.The calculated phonon dispersion curves suggest that this structure is stable at least up to 310 GPa.Oxygen rema/ns a molecular crystal and there is no dissociation in the related pressure range.Moreover,it is found that the phase transition from ζ to post-ζ phase is attributed to phonon softening.The significant change in the optical properties can be used to identify the phase transition.

  19. The optical band gap investigation of PVP-capped ZnO nanoparticles synthesized by sol-gel method (United States)

    Yuliah, Yayah; Bahtiar, Ayi; Fitrilawati, Siregar, Rustam E.


    ZnO Nanoparticles (NPs) has unique natures on their crystal structure, direct band gap and high exciton binding energy, consequently applied in optoelectronic devices such as solar cells, optical wave guide and light emitting diodes (LED). However the drawback was ZnO NPs tend to agglomerate and turn to nano-structured materials with poor properties. Effort to avoid agglomerations generally resolved by surface modification of ZnO NPs to obtain well-dispersed suspension. However changes in the surface of ZnO NPs may change the electronic structure and density of states of ZnO NPs, in turn may change the optical band gap. Thus, the objective of current research is investigation of optical band gap of ZnO NPs due to surface modification by capping agent of poly-4-vinylpyrrolidone (PVP) molecules. Uncapped and PVP-capped ZnO nanoparticles were prepared by sol-gel method. The characteristics of surface modifications were investigated by UV-Vis and Photo Luminescence spectroscopy and Transmission Electron Microscope (TEM). The results shows the surface modification has change the band gap of ZnO NPs obtained at second precipitated stage. In contrast, the change of the optical band gap did not observe due to the surface modification of ZnO NPs obtained at the first stage. It was concluded that PVP capping on ZnO NPs did not affect on the band gap when the capping was performed on first stage. It is emphasized that this statement also supported by TEM images observations.

  20. Investigation into spiral phase plate contrast in optical and electron microscopy

    CERN Document Server

    Juchtmans, Roeland; Lubk, Axel; Verbeeck, Jo


    The use of phase plates in the back focal plane of a microscope is a well established technique in optical microscopy to increase the contrast of weakly interacting samples and is gaining interest in electron microscopy as well. In this paper we study the spiral phase plate (SPP), also called helical, vortex, or two-dimensional Hilbert phase plate, that adds an angularly dependent phase of the form $e^{i\\ell\\phi}$ to the exit wave in Fourier space. In the limit of large collection angles, we analytically calculate that the average of a pair of $\\ell=\\pm1$ SPP images is directly proportional to the gradient squared of the exit wave, explaining the edge contrast previously seen in optical SPP work. The difference between a clockwise-anticlockwise pair of SPP images and conditions where this difference vanishes and the gradient of the exit wave can be seen from one single SPP image, are discussed. Finally, we demonstrate how with three images, one without and one with each of an $\\ell=\\pm1$ SPP, may give enough ...

  1. Tensile stress generation by optical breakdown in tissue: Experimental investigations and numerical simulations

    Energy Technology Data Exchange (ETDEWEB)

    Vogel, A. [Medizinisches Laserzentrum Luebeck (Germany); Scammon, R.J.; Godwin, R.P. [Los Alamos National Lab., NM (United States)


    Biological tissue is more susceptible to damage from tensile stress than to compressive stress. Tensile stress may arise through the thermoelastic response of laser-irradiated media. Optical breakdown, however, has to date been exclusively associated with compressive stress. The authors show that this is appropriate for water, but not for tissues for which the elastic-plastic material response needs to be considered. The acoustic transients following optical breakdown in water and cornea were measured with a fast hydrophone and the cavitation bubble dynamics, which is closely linked to the stress wave generation, was documented by flash photography. Breakdown in water produced a monopolar acoustic signal and a bubble oscillation in which the expansion and collapse phases were symmetric. Breakdown in cornea produced a bipolar acoustic signal coupled with a pronounced shortening of the bubble expansion phase and a considerable prolongation of its collapse phase. The tensile stress wave is related to the abrupt end of the bubble expansion. Numerical simulations using the MESA-2D code were performed assuming elastic-plastic material behavior in a wide range of values for the shear modulus and yield strength. The calculations revealed that consideration of the elastic-plastic material response is essential to reproduce the experimentally observed bipolar stress waves. The tensile stress evolves during the outward propagation of the acoustic transient and reaches an amplitude of 30--40% of the compressive pulse.

  2. Investigation on Thermal and Optical Properties of Hydrogen-Bonded Binary Liquid Crystals (United States)

    Ranjeeth kumar, T.; Sundaram, S.; Vasanthi, T.; Subhasri, P.; Chitravel, T.; Senthil, T. S.; Jayaprakasam, R.; Vijayakumar, V. N.


    A homologous series of hydrogen-bonded liquid crystals (HBLCs) are synthesized and characterized. Intermolecular hydrogen bonding occurs between 4-methoxycinnamic acid (4MCA) and p-n-alkyloxy benzoic acids (nOBA, where n = 3, 7 to 12). These binary complexes have been obtained by following well-designed synthesis route. The subsequent binary complexes have been characterized by polarizing optical thermal microscopy (POM), differential scanning calorimetry (DSC), and Fourier transform infrared spectroscopy (FTIR). The present work explains the details of the association between the mesogenic phase behavior and H-bonding in the homologous series of 4MCA + nOBA. Nematic phase is interrelated with the closed dimers between acid molecules through the formation of strong hydrogen bonds. But, high concentrations are linked to the manifestation of smectic phases that disturb the local order of the nematic phase. As a result, the higher-order mesophases are observed in the present binary complex series. The inclusion of nematic LC (4MCA) in the nOBA alters the melting temperature and the clearing temperature as lower than those of the individual. Also, the wide mesophase regions of the present series are identified compared to those of the constituent mesogens. The optical tilt angle of binary mixtures for smectic C phase and thermal stability factors of the mesogenic phases have been discussed.

  3. Investigation of Two-Dimensional Transition Metal Dichalcogenides by Optical and Scanning Tunneling Spectroscopy (United States)

    Rigosi, Albert F.

    The goal of this dissertation is not only to present works completed and projects initiated and accomplished, but to also attempt to teach some of the material to readers who have limited exposure to condensed matter. I will offer an introduction to two-dimensional transition metal dichalcogenide materials (2D TMDCs) and the mathematics required to understand the research conducted. Some effort will be given on explaining the experimental setups and preparations. Projects that required elaborate sample fabrication and the yielded results will be summarized. These results have heavy implications for the science behind bound electron-hole pairs, the effects of magnetic fields on such pairs, and extracting the useful optical properties from the material systems in which these pairs reside. Specialized fabrication techniques of samples for longer term projects that I led will also be presented, namely those of constructing heterostructures by stacking various 2D TMDCs for exploring the modulated properties of these novel arrangements. The latter portion of this dissertation will cover the nanoscopic dynamics of TMDC heterostructures. The Kramers-Kronig relations will be derived and discussed in detail. Data and results regarding the electronic structure of these materials, their heterostructures, and their custom alloys measured via scanning tunneling microscopy will be presented. Coupled with the measured optical properties, significant numerical quantities that characterize these materials are extracted. There will be several appendices that offer some supplementary information and basic summaries about all the projects that were initiated.

  4. Ag clustering investigation in laser irradiated ion-exchanged glasses by optical and vibrational spectroscopy (United States)

    Trave, E.; Cattaruzza, E.; Gonella, F.; Calvelli, P.; Quaranta, A.; Rahman, A.; Mariotto, G.


    Ion exchange process is widely used to dope silicate glass layers with silver for several applications, ranging from light waveguide to nanostructured composite glass fabrication. The silver-doped structure and its physical properties depend on the preparation parameters as well as on subsequent treatments. In particular, laser irradiation of the ion exchanged glasses has been demonstrated to be an effective tool to control cluster size and size distribution. Nevertheless, a complete comprehension of the basic phenomena and a systematic characterization of these systems are still lacking. In this paper, an extended optical characterization is presented for soda-lime glass slides, doped with silver by Ag+-Na+ ion exchange, thermally treated and irradiated with a Nd:YAG laser beam at different wavelengths, and for different energy density. The samples were characterized by various spectroscopic techniques, namely, optical absorption, photoluminescence and micro-Raman analysis. The availability of all these characterization techniques allowed pointing out a suitable scenario for the Ag clustering evolution as a function of the ion exchange, annealing and laser irradiation parameters.

  5. Investigations of high-speed optical transmission systems employing Absolute Added Correlative Coding (AACC) (United States)

    Dong-Nhat, Nguyen; Elsherif, Mohamed A.; Malekmohammadi, Amin


    A novel multilevel modulation format based on partial-response signaling called Absolute Added Correlative Coding (AACC) is proposed and numerically demonstrated for high-speed fiber-optic communication systems. A bit error rate (BER) estimation model for the proposed multilevel format has also been developed. The performance of AACC is examined and compared against other prevailing On-Off-Keying and multilevel modulation formats e.g. non-return-to-zero (NRZ), 50% return-to-zero (RZ), 67% carrier-suppressed return-to-zero (CS-RZ), duobinary and four-level pulse-amplitude modulation (4-PAM) in terms of receiver sensitivity, spectral efficiency and dispersion tolerance. Calculated receiver sensitivity at a BER of 10-9 and chromatic dispersion tolerance of the proposed system are ˜-28.3 dBm and ˜336 ps/nm, respectively. The performance of AACC is delineated to be improved by 7.8 dB in terms of receiver sensitivity compared to 4-PAM in back-to-back scenario. The comparison results also show a clear advantage of AACC in achieving longer fiber transmission distance due to the higher dispersion tolerance in optical access networks.

  6. A combined use of acoustic and optical devices to investigate suspended sediment in rivers (United States)

    Guerrero, Massimo; Rüther, Nils; Haun, Stefan; Baranya, Sandor


    The use of acoustic and optic devices has become more and more common for estimating suspended sediment loads in rivers. The echo intensity levels (EIL) recorded by means of an Acoustic Doppler Current Profiler (ADCP) have been applied in different methods, which provided relationships between scattering particles features derived from samples (i.e., concentration and grain size) and corresponding backscattering strength and sound attenuation. At the same time, the laser diffraction was applied by an in-stream sampler (LISST-SL) to measure suspended sediment concentration and the corresponding particle size distribution (PSD). These two techniques exhibited different limitations in terms of the measured range of concentration, sensitivity to a certain spectrum of particle sizes, and instruments deploy feasibility especially in large rivers, in a way that the use of sampled PSD by LISST-SL to validate ADCP methods may not be trivial. The aim of this study was to combine the vertical profiling of EIL by an ADCP with results from LISST-SL, eventually demonstrating the possibility of using moving ADCP measurements to detect different suspended matters along a Danube River section characterized by a small tributary junction. At the same time, this work elucidates optical to acoustic method deviations that hinders an actual validation of ADCP methods based on LISST-SL rather than with physical samplings.

  7. Investigation of a Cross-Correlation Based Optical Strain Measurement Technique for Detecting radial Growth on a Rotating Disk (United States)

    Clem, Michelle M.; Woike, Mark R.


    The Aeronautical Sciences Project under NASA`s Fundamental Aeronautics Program is extremely interested in the development of novel measurement technologies, such as optical surface measurements in the internal parts of a flow path, for in situ health monitoring of gas turbine engines. In situ health monitoring has the potential to detect flaws, i.e. cracks in key components, such as engine turbine disks, before the flaws lead to catastrophic failure. In the present study, a cross-correlation imaging technique is investigated in a proof-of-concept study as a possible optical technique to measure the radial growth and strain field on an already cracked sub-scale turbine engine disk under loaded conditions in the NASA Glenn Research Center`s High Precision Rotordynamics Laboratory. The optical strain measurement technique under investigation offers potential fault detection using an applied high-contrast random speckle pattern and imaging the pattern under unloaded and loaded conditions with a CCD camera. Spinning the cracked disk at high speeds induces an external load, resulting in a radial growth of the disk of approximately 50.0-im in the flawed region and hence, a localized strain field. When imaging the cracked disk under static conditions, the disk will be undistorted; however, during rotation the cracked region will grow radially, thus causing the applied particle pattern to be .shifted`. The resulting particle displacements between the two images will then be measured using the two-dimensional cross-correlation algorithms implemented in standard Particle Image Velocimetry (PIV) software to track the disk growth, which facilitates calculation of the localized strain field. In order to develop and validate this optical strain measurement technique an initial proof-of-concept experiment is carried out in a controlled environment. Using PIV optimization principles and guidelines, three potential speckle patterns, for future use on the rotating disk, are developed

  8. Preliminary investigations toward nighttime aerosol optical depth retrievals from the VIIRS day/night band

    Directory of Open Access Journals (Sweden)

    R. S. Johnson


    Full Text Available A great need exists for reliable nighttime aerosol products at high spatial and temporal resolution. In this concept demonstration study, using Visible/Infrared Imager/Radiometer Suite (VIIRS Day/Night Band (DNB observations on the Suomi National Polar-orbiting Partnership (NPP satellite, a new method is proposed for retrieving nighttime aerosol optical depth (τ using the contrast between regions with and without artificial surface lights. Evaluation of the retrieved τ values against daytime AERONET data from before and after the overpass of the VIIRS satellite over the Cape Verde, Grand Forks, and Alta Floresta AERONET stations yields a coefficient of determination (r2 of 0.71. This study suggests that the VIIRS DNB has the potential to provide useful nighttime aerosol detection and property retrievals.

  9. Investigations on Shaped Mirror Systems in Quasi-Optical Mode Converters Based on Irradiance Moments Method

    Directory of Open Access Journals (Sweden)

    Hai Wang


    Full Text Available A method of transforming high-order Gaussian beams (GBs mode into circular symmetry fundamental Gaussian beam (FGB mode with arbitrary waist size is presented using irradiance moments method in quasi-optical (QO mode converters. The double shaped mirrors correcting amplitude and phase simultaneously are generated by a single incidence irradiance sampling data and known ideal output FGB taking advantage of linear moment matching technique and Fresnel diffraction theory, which can be applied to a wide frequency range especially significant for terahertz band. The numerical coding procedure of creating double correcting mirrors and its fast convergence speed are discussed at 325 GHz. Numerical and experimental comparisons reveal the conclusion that enhancing surface precision and increasing moments order can improve main lobe levels.

  10. Experimental investigation of a four-qubit linear-optical quantum logic circuit (United States)

    Stárek, R.; Mičuda, M.; Miková, M.; Straka, I.; Dušek, M.; Ježek, M.; Fiurášek, J.


    We experimentally demonstrate and characterize a four-qubit linear-optical quantum logic circuit. Our robust and versatile scheme exploits encoding of two qubits into polarization and path degrees of single photons and involves two crossed inherently stable interferometers. This approach allows us to design a complex quantum logic circuit that combines a genuine four-qubit C3Z gate and several two-qubit and single-qubit gates. The C3Z gate introduces a sign flip if and only if all four qubits are in the computational state |1>. We verify high-fidelity performance of this central four-qubit gate using Hofmann bounds on quantum gate fidelity and Monte Carlo fidelity sampling. We also experimentally demonstrate that the quantum logic circuit can generate genuine multipartite entanglement and we certify the entanglement with the use of suitably tailored entanglement witnesses.

  11. Investigation of nonlinear optical properties of various organic materials by the Z-scan method (United States)

    Ganeev, R. A.; Boltaev, G. S.; Tugushev, R. I.; Usmanov, T.


    We have studied the nonlinear optical properties of various organic materials (vegetable oil, juice, wine, cognac, Coca-Cola and Fanta drinks, Nescafé coffee, tea, gasoline, clock oil, glycerol, and polyphenyl ether) that are used in everyday life. Their nonlinearities have been studied by the Z-scan method in the near-IR and visible spectral ranges. We have shown that the majority of samples possess a nonlinear absorption; however, some of the studied materials show a strong saturated absorption and nonlinear refraction. Red wine and glycerol proved to be the most interesting materials. For these samples, we have observed a change in the sign of the nonlinear absorption with increasing laser intensity, which was attributed to the competition between two-photon absorption and saturated absorption.

  12. Investigation of Third Order Optical Nonlinearity and Reverse Saturable Absorption of Octa-alkoxy Metallophthalocyanines (United States)

    Sanghadasa, Mohan; Shin, In-Seek; Barr, Thomas A.; Clark, Ronald D.; Guo, Huai-Song; Martinez, Angela; Penn, Benjamin G.


    In recent years, there has been a growing interest in the development of passive optical power limiters for the protection of the human eye and solid-state sensors from damage caused by energetic light pulses and also for other switching applications. One of the key issues involved is the search for appropriate materials that show effective reverse saturable absorption. Phthalocyanines seem to be good candidates for such applications because of their higher third order nonlinearity and the unique electronic absorption characteristics. A series of 1,4,8,11,15, 18,22,25-octa-alkoxy metallophthalocyanines containing various central metal atoms such as zinc, copper, palladium, cobalt and nickel were characterized for their third order nonlinearity and for their nonlinear absorptive properties to evaluate their suitability to function as reverse saturable absorbers.

  13. Synthesis and investigation of optical properties of ZnS nanostructures

    Indian Academy of Sciences (India)

    Neslihan Üzar; M Çetin Arikan


    Structural characterizations of wurtzite zinc sulfide (ZnS) nanostructures synthesized by vapour–liquid–solid technique (VLS) were carried out by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) analyses. Spectral dependence of photoluminescence (PL) was also carried out for optical characterization. PL results indicate that the bandgap energy of bulk ZnS which is 3.68 eV at room temperature changes from 3.7 eV to 3.72 eV depending on the size of the structures. We also supported these results by calculating the bandgap energies theoretically with using the infinite potential well approximation for 1D structures.

  14. Optical Characteristics Investigation of the Cold Argon Plasma Jet for the Medical Applications (United States)

    Nguyen-Kuok, Shi; Malakhov, Yury; Bach, Sy Minh; Korotkikh, Ivan


    The medical setup was designed for the treatment of wounds, disinfection of inflammation, for the destruction of damaged cells. The results of experimental determination of the optical characteristics of Argon cold plasma at atmospheric pressure are presented in the paper. The main components of the experimental setup are plasma torch, spectrometer, photo-electron multiplier, oscilloscope, gas consumption QAr = 1 - 20 l/min. Spectrum of the plasma jet is obtained using the grating spectrometer Spectra with radiometric calibration, operating in the visible range λ = 380 - 760 nm. The sun-blind photodetector was used for determination of the intensity of radiation in the UV range λ = 190 - 380 nm. The emission spectrum consists of a continuous radiation and the emissions of atoms and ions ArI and ArII. The analysis of spectral lines was carried out.

  15. An investigation on a novel PDLC film’s fabrication and its electro-optical properties

    Institute of Scientific and Technical Information of China (English)


    A polymer dispersed liquid crystal (PDLC) film that has good electro-optical properties is produced by the method of polymerized-induced phase separation. Based on the application foreground, its capability parameters, such as contrast ratio, work voltage, and visual angle, are characterized for the first time by a white light but not a fixed wavelength light. The results show the PDLC film has a low work-voltage of 20 V, more than 150° visual angle, high stability, and long lifetime. The differences between plastic and glass ITO-coated substrates of PDLC films are also studied in this paper. The plastic substrate has better property and will have a wider perspective especially in the portable, tender and folded display devices. Due to adjustable properties of film by electric field, PDLC has the potential application for display device, sensor, switch, grating, and new generation analytical apparatus.

  16. Photoemission Electron Microscopy as a tool for the investigation of optical near fields

    CERN Document Server

    Cinchetti, M; Nepjiko, S A; Sch"onhense, G; Rochholz, H; Kreiter, M


    Photoemission electron microscopy was used to image the electrons photoemitted from specially tailored Ag nanoparticles deposited on a Si substrate (with its native oxide SiO$_{x}$). Photoemission was induced by illumination with a Hg UV-lamp (photon energy cutoff $\\hbar\\omega_{UV}=5.0$ eV, wavelength $\\lambda_{UV}=250$ nm) and with a Ti:Sapphire femtosecond laser ($\\hbar\\omega_{l}=3.1$ eV, $\\lambda_{l}=400$ nm, pulse width below 200 fs), respectively. While homogeneous photoelectron emission from the metal is observed upon illumination at energies above the silver plasmon frequency, at lower photon energies the emission is localized at tips of the structure. This is interpreted as a signature of the local electrical field therefore providing a tool to map the optical near field with the resolution of emission electron microscopy.

  17. An investigation of the influence of reconceptualization of demonstrative experimental activities of optics in high school

    Directory of Open Access Journals (Sweden)

    Jair Lúcio Prados Ribeiro


    Full Text Available In this work, we analyze the influence that the use of demonstrative experiments can bring to the learning of optics. It is assumed that the development of experimental activities, when reconceptualized according to Hodson proposal, tends to contribute to the generation of cognitive conflicts when compared to traditional didactic experience. Justifications are given for an analysis of changes under a Piagetian bias, reconciled with Hodson proposal. The methodology used to structure the topics presentations was quasi-experimental, contrasting an experimental group with a control group. The measuring of the effectiveness of the suggested working method was made from a quantitative analysis, which identified some of the topics discussed had better results in learning, being more tied to the experiments carried out.

  18. Dip coated nickel zinc oxide thin films: Structural, optical and magnetic investigations (United States)

    Kayani, Zohra Nazir; Kiran, Faiza; Riaz, Saira; Zia, Rehana; Naseem, Shahzad


    Dip-coating technique was used to deposit NiZnO thin films on glass substrates at varying withdrawal speed in the range of 150-350 mm/s and annealed at 500 °C for 4 h. X-ray diffraction (XRD) results showed that the deposited NiZnO thin films have a pure wurtzite structure without any significant change in the structure caused by substituting Zn ion with Ni ion. Crystallite size increased from 248 to 497 nm with increase in withdrawal speed. Vibrating Sample magnetometer (VSM) results indicated that NiZnO thin films exhibit ferromagnetic properties. Increase in saturation magnetization with increase in withdrawal speed is observed. Evaluated optical band gap of the films reduced from 3.18 eV to 2.50 eV with the increase in withdrawal speed of the substrate.

  19. Investigating macroscopic quantum superpositions and the quantum-to-classical transition by optical parametric amplification

    CERN Document Server

    De Martini, Francesco


    The present work reports on an extended research endeavor focused on the theoretical and experimental realization of a macroscopic quantum superposition (MQS) made up with photons. As it is well known, this intriguing, fundamental quantum condition is at the core of a famous argument conceived by Erwin Schroedinger, back in 1935. The main experimental challenge to the actual realization of this object resides generally on the unavoidable and uncontrolled interactions with the environment, i.e. the decoherence leading to the cancellation of any evidence of the quantum features associated with the macroscopic system. The present scheme is based on a nonlinear process, the "quantum injected optical parametric amplification", that maps by a linearized cloning process the quantum coherence of a single - particle state, i.e. a Micro - qubit, into a Macro - qubit, consisting in a large number M of photons in quantum superposition. Since the adopted scheme was found resilient to decoherence, the MQS\\ demonstration wa...

  20. The Optical Absorption Coefficient of Maize Grains Investigated by Photoacoustic Spectroscopy (United States)

    Rodríguez-Páez, C. L.; Carballo-Carballo, A.; Rico-Molina, R.; Hernández-Aguilar, C.; Domínguez-Pacheco, A.; Cruz-Orea, A.; Moreno-Martínez, E.


    In the maize and tortilla industry, it is important to characterize the color of maize ( Zea mays L.) grain, as it is one of the attributes that directly affect the quality of the tortillas consumed by the population. For this reason, the availability of alternative techniques for assessing and improving the quality of grain is valued. Photoacoustic spectroscopy has proven to be a useful tool for characterizing maize grain. So, the objective of the present study was to determine the optical absorption coefficient β of the maize grain used to make tortillas from two regions of Mexico: (a) Valles Altos, 2012-2013 production cycle and (b) Guasave, Sinaloa, 2013-2014 production cycle. Traditional reflectance measurements, physical characteristics of the grain and nutrient content were also calculated. The experimental results show different characteristics for maize grains.

  1. Experimental and theoretical investigation of optical nonlinearities in (nitrovinyl)-1H-pyrazole derivative (United States)

    Dwivedi, Y.; de Boni, L.; Gonçalves, P. J.; Mairink, L. M.; Menegatti, R.; Fonseca, T. L.; Zilio, S. C.


    This work reports on the optical nonlinearities of a newly synthesized pyrazole derivative, namely (E)-1-(4-chlorophenyl)-4-(2-nitrovinyl)-1H-pyrazole. The Z-scan technique with femtosecond laser pulses was used to determine the two-photon absorption (2PA) cross-section spectrum, which presents a maximum of 67 GM at 690 nm. We have combined hyper-Rayleigh scattering (HRS) experiments and second-order Møller-Plesset perturbation theory (MP2) calculations to study the first hyperpolarizability (βHRS). It was found that the MP2/6-311+G(d) model, taking into account solvent and dispersion effects, provides the βHRS value of 40 × 10-30 cm5/esu for the compound, in good agreement with the experimental result of 45 ± 2 × 10-30 cm5/esu.

  2. Investigation of basal cell carcinoma using dynamic focus optical coherence tomography. (United States)

    Avanaki, Mohammad R N; Hojjatoleslami, Ali; Sira, Mano; Schofield, John B; Jones, Carole; Podoleanu, Adrian Gh


    Optical coherence tomography (OCT) is becoming a popular modality for skin tumor diagnosis and assessment of tumor size and margin status. We conducted a number of imaging experiments on periocular basal cell carcinoma (BCC) specimens using an OCT configuration. This configuration employs a dynamic focus (DF) procedure where the coherence gate moves synchronously with the peak of the confocal gate, which ensures better signal strength and preservation of transversal resolution from all depths. A DF-OCT configuration is used to illustrate morphological differences between the BCC and its surrounding healthy skin in OCT images. The OCT images are correlated with the corresponding histology images. To the best of our knowledge, this is the first paper to look at DF-OCT imaging in examining periocular BCC.

  3. Investigation of optical and spectroscopic properties of Sm3+ ions in CaBAl glasses (United States)

    Brito, D. R. N.; Queiroz, M. N.; Barboza, M. J.; Steimacher, A.; Pedrochi, F.


    Samples of CaBAl glass with composition of (25-x)CaO-50B2O3-15Al2O3-10CaF2-xSm2O3, with Sm2O3 concentration varying from 0.5 to 7 wt%, were prepared by using melt-quenching method in air atmosphere. The samples were prepared with different concentrations of Sm2O3, aiming to understand how the dopant changes the optical and spectroscopic properties of the glass. The doped CaBAl glasses were studied by means of volumetric density measurements, refractive index, optical absorption, luminescence at room temperature, luminescence as function of the temperature and radiative lifetime. All results were discussed in function of Sm2O3 concentration. The measured volumetric density and polarizability showed an increase with Sm2O3 doping. The refractive index showed a small increase due to RE doping, although within the errors. The absorption bands were attributed to Sm3+ transitions from the ground state 6H5/2 to the various excited states. The luminescence spectra present emission bands assigned to the appropriate electronic f-f transitions of Sm3+ ions; there are four emission bands at 565, 602, 649 and 710 nm. The luminescence quenching was observed up to 2 wt% of Sm2O3. The O/R ratio as function of the Sm2O3 concentration showed changes in the symmetry site with addition of Sm2O3. The CIE 1931 diagram presented a reddish-orange shift color with Sm2O3 doping. The luminescence intensity presents a decrease with temperature increase for all studied samples. The experimental lifetime decreases with the increase of Sm2O3, mainly due to ion-ion interaction.

  4. Investigation of optical, structural and morphological properties of nanostructured boron doped TiO2 thin films

    Indian Academy of Sciences (India)

    Savaş Sönmezoǧlu; Banu Erdoǧan; İskender Askeroǧlu


    Pure and different ratios (1, 3, 5, 7 and 10%) of boron doped TiO2 thin films were grown on the glass substrate by using sol–gel dip coating method having some benefits such as basic and easy applicability compared to other thin film production methods. To investigate the effect of boron doped on the physical properties of TiO2, structural, morphological and optical properties of growth thin films were examined. 1% boron-doping has no effect on optical properties of TiO2 thin film; however, optical properties vary with > 1%. From X-ray diffraction spectra, it is seen that TiO2 thin films together with doping of boron were formed along with TiB2 hexagonal structure having (111) orientation, B2O3 cubic structure having (310) orientation, TiB0.024O2 tetragonal structure having rutile phase (110) orientation and polycrystalline structures. From SEM images, it is seen that particles together with doping of boron have homogeneously distributed and held onto surface.

  5. First-Principles Investigation of Phase Stability, Electronic Structure and Optical Properties of MgZnO Monolayer

    Directory of Open Access Journals (Sweden)

    Changlong Tan


    Full Text Available MgZnO bulk has attracted much attention as candidates for application in optoelectronic devices in the blue and ultraviolet region. However, there has been no reported study regarding two-dimensional MgZnO monolayer in spite of its unique properties due to quantum confinement effect. Here, using density functional theory calculations, we investigated the phase stability, electronic structure and optical properties of MgxZn1−xO monolayer with Mg concentration x range from 0 to 1. Our calculations show that MgZnO monolayer remains the graphene-like structure with various Mg concentrations. The phase segregation occurring in bulk systems has not been observed in the monolayer due to size effect, which is advantageous for application. Moreover, MgZnO monolayer exhibits interesting tuning of electronic structure and optical properties with Mg concentration. The band gap increases with increasing Mg concentration. More interestingly, a direct to indirect band gap transition is observed for MgZnO monolayer when Mg concentration is higher than 75 at %. We also predict that Mg doping leads to a blue shift of the optical absorption peaks. Our results may provide guidance for designing the growth process and potential application of MgZnO monolayer.

  6. Investigation of optical limiting properties of Aluminium nanoparticles prepared by pulsed laser ablation in different carrier media (United States)

    Kuladeep, Rajamudili; Jyothi, L.; Prakash, P.; Mayank Shekhar, S.; Durga Prasad, M.; Narayana Rao, D.


    In this communication, we carried out the systematic investigation of nonlinear absorption and scattering properties of Aluminium nanoparticles (Al NPs) in various polar and non-polar solvents. Al NPs were synthesized with pulsed Nd:YAG laser operated at 1064 nm by ablating Al target in polar and non-polar liquid environment like chloroform, chlorobenzene, toluene, benzene, and carbon tetrachloride. Synthesized Al NPs colloids of various solvents differ in appearance and UV-Vis extinction spectra exhibit absorption in the UV region. The characterization of Al NPs performed by Transmission electron microscopy (TEM) studies reveal that NPs are made up of a well crystallized Al inner part (bright zone) embedded with an amorphous metal Al shell (dark region). Growth, aggregation, and precipitation mechanisms which influence the optical properties and stability of NPs are found to be related to the dipole moment of the surrounding liquid environment. The nonlinear absorption and scattering studies are performed by open aperture Z-scan technique with 532 nm under nanosecond pulse excitation. The Z-scan measurements are fitted theoretically to estimate both two-photon absorption (TPA) and nonlinear scattering (NLS) coefficients. In polar solvents like chlorobenzene, chloroform synthesized Al NPs exhibited higher TPA, NLS coefficient values, and lower optical limiting threshold values in comparison with partially polar solvent like toluene and non-polar solvents like benzene and carbontetrachloride. These results indicate the potential use of Al NPs as a versatile optical limiting material.

  7. An optical and structural investigation into CdTe nanocrystals embedded into the tellurium lithium borophosphate glass matrix

    Institute of Scientific and Technical Information of China (English)

    WAGEH; S


    Cadmium telluride nanocrystals that form in the TeO2-Li2O-B2O3-P2O5 glass matrix have been synthesized and studied.They are investigated by X-ray diffraction(XRD),optical transmission and infrared spectroscopy.It has been shown that the long annealing time effect on present samples leads to the growth of CdTe nanoparticles and an increase of tellurium oxide on the surface of nanocrystallites.On the other hand,the infrared spectroscopy shows that the phosphate and borate networks of the glass matrices are modified with doping by CdTe nanoparticles.

  8. Investigation of noise in Lightwave Synthesized Frequency Sweeper seeded LIDAR anemometers from leakage through the Acousto Optic Modulators

    DEFF Research Database (Denmark)

    Pedersen, Anders Tegtmeier; Lindelöw, Per Jonas Petter


    Lightwave Synthesized Frequency Sweepers (LSFS) have potential use as lightsources in lidar anemometers. In this paper noise due to leakage in the acousto optic modulators in an LSFS is investigated. Theoretical expressions describing the build-up of noise in the LSFS due to leakage are derived...... Train (FSPT) modulated lidars the leakage will give rise to rapidly growing noise in the bins which corresponds to the signal from low radial wind velocities. It is likely that noise canceling techniques similar to those used for RIN removal has to be deployed for measurements of low wind velocities....

  9. Dynamics, OH distributions and UV emission of a gliding arc at various flow-rates investigated by optical measurements

    DEFF Research Database (Denmark)

    Zhu, Jiajian; Sun, Zhiwei; Li, Zhongshan;


    emission of the gliding arc were investigated by optical methods. High-speed photography was utilized to reveal flow-rate dependent dynamics such as ignitions, propagation, short-cutting events, extinctions and conversions of the discharge from glowtype to spark-type. Short-cutting events and ignitions...... hundreds of microseconds after being electronically short-cut by a newly ignited arc. The extinction time decreases with the increase of the flow rate. The frequency of the conversion of a discharge from glow-type to spark-type increases with the flow rate. Additionally, spatial distributions of ground...

  10. Investigation of optical and interfacial properties of Ag/Ta{sub 2}O{sub 5} metal dielectric multilayer structure

    Energy Technology Data Exchange (ETDEWEB)

    Sarkar, P., E-mail:; Jena, S.; Tokas, R. B.; Thakur, S.; Sahoo, N. K. [Atomic & Molecular Physics Division, Bhabha Atomic Research Centre, Mumbai-400085 (India); Rao, K. D.; Misal, J. S.; Prathap, C. [Optics and Thin Film Laboratory, BARC-Vizag, Autonagar, Visakhapatnam-530012 (India)


    One-dimensional periodic metal-dielectric multilayer thin film structures consisting of Ag and Ta{sub 2}O{sub 5} alternating layers are deposited on glass substrate using RF magnetron sputtering technique. The spectral property of the multilayers has been investigated using spectrophotometry technique. The optical parameters such as refractive index, extinction coefficient, band gap etc., along with film thickness as well as the interfacial layer properties which influence these properties have been probed with spectroscopic ellipsometry technique. Atomic force microscopy has been employed to characterize morphological properties of this metal-dielectric multilayer.

  11. Investigation on the effect of beam divergence angle upon output waveform based on stimulated Brillouin scattering optical limiting

    Institute of Scientific and Technical Information of China (English)

    Hasi Wu-Li-Ji; Lu Huan-Huan; Gong Sheng; Fu Mei-Ling; Lin Zhi-Wei; Lin Dian-Yang; He Wei-Ming


    This paper investigates the effect of beam divergence angle on output waveform based on stimulated Brillouin scattering optical limiting. Output waveforms in the case of different pump divergence angles are numerically simulated,and validated in a Nd:YAG seed-injected laser system. The results indicate that a small pump divergence angle can lead to good interaction between pump and Stokes, and a platform can be easily realized in the transmitted waveform.In contrast, a peak followed by the platform appears when the divergence angle becomes large.

  12. Investigation and comparison of analytical, numerical, and experimentally measured coupling losses for multi-step index optical fibers. (United States)

    Aldabaldetreku, Gotzon; Durana, Gaizka; Zubia, Joseba; Arrue, Jon; Poisel, Hans; Losada, María


    The aim of the present paper is to provide a comprehensive analysis of the coupling losses in multi-step index (MSI) fibres. Their light power acceptance properties are investigated to obtain the corresponding analytical expressions taking into account longitudinal, transverse, and angular misalignments. For this purpose, a uniform power distribution is assumed. In addition, we perform several experimental measurements and computer simulations in order to calculate the coupling losses for two different MSI polymer optical fibres (MSI-POFs). These results serve us to validate the theoretical expressions we have obtained.

  13. Optical and Structural Investigation of CdSe Quantum Dots Dispersed in PVA Matrix and Photovoltaic Applications


    Pallabi Phukan; Dulen Saikia


    CdSe quantum dots (QDs) dispersed in polyvinyl alcohol (PVA) matrix with their sizes within the quantum dot regime have been synthesized via a simple heat induced thermolysis technique. The effect of the concentrations of the cadmium source on the optical properties of CdSe/PVA thin films was investigated through UV-Vis absorption spectroscopy. The structural analysis and particle size determination as well as morphological studies of the CdSe/PVA nanocomposite thin films were done with the h...

  14. Room temperature photoinduced magnetism in [py.H]{sub 3}[FeCl{sub 4}]{sub 2}Cl

    Energy Technology Data Exchange (ETDEWEB)

    Baniasadi, F. [Physics Department, Shahid Beheshti University, Tehran (Iran, Islamic Republic of); Tehranchi, M.M., E-mail: [Physics Department, Shahid Beheshti University, Tehran (Iran, Islamic Republic of); Fathi, M.B. [Physics Department, Kharazmi University, Tehran (Iran, Islamic Republic of); Hamidi, S.M. [Laser and Plasma Research Institute, Shahid Beheshti University, Tehran (Iran, Islamic Republic of); Safari, N.; Amani, V. [Faculty of Chemistry, Shahid Beheshti University, Tehran (Iran, Islamic Republic of)


    Photoinduced magnetism in a homogeneous solution of [py.H]{sub 3}[FeCl{sub 4}]{sub 2}Cl is measured by Faraday rotation in visible light (λ∼450–750 nm) at room temperature. The physics of this phenomenon may be attributed to electronic transitions caused by absorption of light. X-ray diffraction and Debye function analysis are therefore applied to find the abundant unit of molecules dissolved in the solution which are being further utilized to investigate the electronic structure and molecular orbitals by means of hybrid density function theory (B3LYP). Faraday rotation is observed at certain wavelengths consistent with energy differences of HOMO-LUMO energy levels. Thus this work puts forward a new material with certain photomagnetic properties which may be used in fabrication of room temperature magneto-optical switches. - Highlights: • Photoinduced magnetism in (FeCl{sub 4}){sub 2}(py.H){sub 3}Cl is illustrated via Faraday rotation. • The abundant unit of molecule is characterized by Debye function analysis of XRD. • PIM in the molecule is attributed to the charge transfer between HOMO-LUMO.

  15. EPR spectroscopy as a tool for investigation of differences in radical status in wheat plants of various tolerances to osmotic stress induced by NaCl and PEG-treatment. (United States)

    Labanowska, Maria; Filek, Maria; Kurdziel, Magdalena; Bidzińska, Ewa; Miszalski, Zbigniew; Hartikainen, Hélina


    Two kinds of wheat genotypes with different tolerance to osmotic stress (NaCl and PEG-treatment) were investigated with biochemical analyses, including the measurements of total antioxidant capacity, 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging activity, reducing power and starch content. The results were compared with electron paramagnetic resonance (EPR) data concerning the nature and amounts of stable long lived radicals present in the control and stressed plants. In addition, the changes in manganese content upon stress conditions were monitored. Different mechanisms of protection against PEG stress in sensitive and tolerant wheat genotypes were postulated. In sensitive genotypes, electrons were created in excess in stress conditions, and were stabilized by polysaccharide molecules, whereas in tolerant genotypes, protection by antioxidants dominated. Moreover, the quinone-semiquinone balance shifted towards semiquinone, which became the place of electron trapping. NaCl-treatment yielded significant effects mainly in sensitive genotypes and was connected with the changes of water structure, leading to inactivation of reactive oxygen species by water molecules.

  16. SCC investigation of low alloy ultra-high strength steel 30CrMnSiNi2A in 3.5wt% NaCl solution by slow strain rate technique

    Directory of Open Access Journals (Sweden)

    Liu Jianhua


    Full Text Available To evaluate stress corrosion cracking (SCC mechanism of low alloy ultra-high strength steel 30CrMnSiNi2A in environment containing NaCl, SCC behavior of the steel in 3.5wt% NaCl solution is investigated by slow strain rate technique (SSRT with various strain rates and applied potentials, surface analysis technique, and electrochemical measurements. SCC susceptibility of the steel increases rapidly with strain rate decreasing from 1 × 10−5 s−1 to 5 × 10−7 s−1, and becomes stable when strain rate is lower than 5 × 10−7 s−1. SCC propagation of the steel in the solution at open circuit potential (OCP needs sufficient hydrogen which is supplied at a certain strain rate. Fracture surface at OCP has similar characteristics with that at cathodic polarization −1000 mVSCE, which presents characteristic fractography of hydrogen induced cracking (HIC. All of these indicate that SCC behavior of the steel in the solution at OCP is mainly controlled by HIC rather than anodic dissolution (AD.

  17. SCC investigation of low alloy ultra-high strength steel 30CrMnSiNi2A in 3.5wt%NaCl solution by slow strain rate technique

    Institute of Scientific and Technical Information of China (English)

    Liu Jianhua; Guo Qiang; Yu Mei; Li Songmei


    To evaluate stress corrosion cracking (SCC) mechanism of low alloy ultra-high strength steel 30CrMnSiNi2A in environment containing NaCl, SCC behavior of the steel in 3.5wt%NaCl solution is investigated by slow strain rate technique (SSRT) with various strain rates and applied potentials, surface analysis technique, and electrochemical measurements. SCC susceptibility of the steel increases rapidly with strain rate decreasing from 1 · 10?5 s?1 to 5 · 10?7 s?1, and becomes stable when strain rate is lower than 5 · 10?7 s?1. SCC propagation of the steel in the solution at open circuit potential (OCP) needs sufficient hydrogen which is supplied at a certain strain rate. Fracture surface at OCP has similar characteristics with that at cathodic polarization ?1000 mVSCE, which presents characteristic fractography of hydrogen induced cracking (HIC). All of these indicate that SCC behavior of the steel in the solution at OCP is mainly controlled by HIC rather than anodic dissolution (AD).

  18. Determination of 36Cl in nuclear waste from reactor decommissioning

    DEFF Research Database (Denmark)

    Hou, Xiaolin; Frøsig, Lars; Nielsen, Sven Poul


    An analytical method for the determination of Cl-36 in nuclear waste such as graphite, heavy concrete, steel, aluminum, and lead was developed. Several methods were investigated for decomposing the samples. AgCl precipitation was used to separate Cl-36 from the matrix elements, followed by ion...... of this analytical method for Cl-36 is 14 mBq. The method has been used to determine Cl-36 in heavy concrete, aluminum, and graphite from the Danish DR-2 research reactor....

  19. Investigation of alterations in multifractality in optical coherence tomographic images of in vivo human retina (United States)

    Das, Nandan Kumar; Mukhopadhyay, Sabyasachi; Ghosh, Nirmalya; Chhablani, Jay; Richhariya, Ashutosh; Divakar Rao, Kompalli; Sahoo, Naba Kishore


    Optical coherence tomography (OCT) enables us to monitor alterations in the thickness of the retinal layer as disease progresses in the human retina. However, subtle morphological changes in the retinal layers due to early disease progression often may not lead to detectable alterations in the thickness. OCT images encode depth-dependent backscattered intensity distribution arising due to the depth distributions of the refractive index from tissue microstructures. Here, such depth-resolved refractive index variations of different retinal layers were analyzed using multifractal detrended fluctuation analysis, a special class of multiresolution analysis tools. The analysis extracted and quantified microstructural multifractal information encoded in normal as well as diseased human retinal OCT images acquired in vivo. Interestingly, different layers of the retina exhibited different degrees of multifractality in a particular retina, and the individual layers displayed consistent multifractal trends in healthy retinas of different human subjects. In the retinal layers of diabetic macular edema (DME) subjects, the change in multifractality manifested prominently near the boundary of the DME as compared to the normal retinal layers. The demonstrated ability to quantify depth-resolved information on multifractality encoded in OCT images appears promising for the early diagnosis of diseases of the human eye, which may also prove useful for detecting other types of tissue abnormalities from OCT images.

  20. Investigating the merger origin of Early-Type Galaxies using ultra-deep optical images

    CERN Document Server

    Duc, P -A; Alatalo, K; Blitz, L; Bois, M; Bournaud, F; Bureau, M; Cappellari, M; Cote, P; Davies, R L; Davis, T A; de Zeeuw, P T; Emsellem, E; Ferrarese, L; Ferriere, E; Gwyn, S; Khochfar, S; Krajnovic, D; Kuntschner, H; Lablanche, P -Y; MacArthur, L; McDermid, R M; Michel-Dansac, L; Morganti, R; Naab, T; Oosterloo, T; Sarzi, M; Scott, N; Serra, P; Weijmans, A; Young, L M


    The mass assembly of galaxies leaves various imprints on their surroundings, such as shells, streams and tidal tails. The frequency and properties of these fine structures depend on the mechanism driving the mass assembly: e.g. a monolithic collapse, rapid cold-gas accretion followed by violent disk instabilities, minor mergers or major dry / wet mergers. Therefore, by studying the outskirts of galaxies, one can learn about their main formation mechanism. I present here our on-going work to characterize the outskirts of Early-Type Galaxies (ETGs), which are powerful probes at low redshift of the hierarchical mass assembly of galaxies. This work relies on ultra-deep optical images obtained at CFHT with the wide-field of view MegaCam camera of field and cluster ETGs obtained as part of the Atlas-3D and NGVS projects. State of the art numerical simulations are used to interpret the data. The images reveal a wealth of unknown faint structures at levels as faint as 29 mag arcsec-2 in the g-band. Initial results fo...

  1. Validation of a Hybrid Microwave-Optical Monitor to Investigate Thermal Provocation in the Microvasculature. (United States)

    Al-Armaghany, Allann; Tong, Kenneth; Highton, David; Leung, Terence S


    We have previously developed a hybrid microwave-optical system to monitor microvascular changes in response to thermal provocation in muscle. The hybrid probe is capable of inducing deep heat from the skin surface using mild microwaves (1-3 W) and raises the tissue temperature by a few degrees Celsius. This causes vasodilation and the subsequent increase in blood volume is detected by the hybrid probe using near infrared spectroscopy. The hybrid probe is also equipped with a skin cooling system which lowers the skin temperature while allowing microwaves to warm up deeper tissues. The hybrid system can be used to assess the condition of the vasculature in response to thermal stimulation. In this validation study, thermal imaging has been used to assess the temperature distribution on the surface of phantoms and human calf, following microwave warming. The results show that the hybrid system is capable of changing the skin temperature with a combination of microwave warming and skin cooling. It can also detect thermal responses in terms of changes of oxy/deoxy-hemoglobin concentrations.

  2. Investigation of optical, structural properties of Eu3+ by Mn2+ in barium alumino borosilicate glasses (United States)

    Lakshmi, P. Vijaya; Rao, T. G. V. M.; Neeraja, K.; Krishna Reddy, D. V.; Rami Reddy, M.


    The Mn2+ ions doped Eu2O3sbnd BaOsbnd Al2O3sbnd B2O3sbnd SiO2 glasses are synthesized by conventional melt quenching method. The effect of Mn2+ ions on spectroscopic, structural properties of Eu3+ ions in glass networks is analysed. An analysis of XRD traces evidently suggests the glassy nature of the prepared samples. The UV-Vis absorption and the luminescence spectra have been used to study the variations in the optical character of Eu3+ ions. In luminescence spectra five bands can be observed at about 578, 590, 612, 653 and 702 nm as a result of transitions of Eu3+ ions from 5D0→7F0, 1, 2, 3, 4 respectively. By gradual increment of MnO mol% in the glass matrix, the strong variation in the intensity of emission band are observed at about 612 nm (5D0→7F2). The non-radiative energy transfer (Mn2+ ↔ Eu3+) and concentration quenching are observed in the prepared glasses. The ESR spectra exhibit a sixtet hyperfine structure centered at g = ∼2.0047 which suggests that manganese ions predominantly occupy octahedral positions.

  3. Investigations on structural, optical and magnetic properties of solution-combustion-synthesized nanocrystalline iron molybdate

    Indian Academy of Sciences (India)



    Iron molybdate $\\beta$-Fe$_2$(MoO$_4$)$_3$ nanoparticles were synthesized by exploiting the self-propagating hightemperaturecombustion strategy using hexamine as a fuel. The obtained $\\beta$-Fe$_2$(MoO$_4$)$_3$ nanoparticles exhibited the orthorhombic crystalline structure, which is evidenced from the XRD pattern. FT-IR spectrum revealed the existence of stretching and bending vibrations of Mo–O–Mo and O–Mo–O bonding in the nanocrystals. The binding energy peaks in the X-ray photoelectron spectroscopy (XPS) spectrum positioned at 710 and 725, 231 and 235 and 530 eV, respectively, correspond to the Fe(2p), Mo(3d) and O(1s) orbitals. Absorption spectrum of nanoparticles showed adequate absorbance of visible region photons of the nanoparticles and also optical bandgap valueof $\\beta$-Fe$_2$(MoO$_4$)$_3$ nanoparticles as 2.26 eV, which is calculated using the Kubelka–Munk function. The existence of Fe$^{3+}$ and Mo$^{6+}$ in $\\beta$-Fe$_2$(MoO$_4$)$_3$ is authenticated with the aid of electron paramagnetic resonance spectrum measurements. The obtained nanoparticles have showed methylene blue dye degradation of 98.4% under sunlightirradiation.

  4. Full investigation of the resonant frequency servo loop for resonator fiber-optic gyro. (United States)

    Ma, Huilian; Lu, Xiao; Yao, Linzhi; Yu, Xuhui; Jin, Zhonghe


    Resonator fiber-optic gyro (RFOG) is a high-accuracy inertial rotation sensor based on the Sagnac effect. A high-accuracy resonant frequency servo loop is indispensable for a high-performance RFOG. It is composed of a frequency discriminator, a loop filter, and a laser actuator. Influences of the loop parameters are fully developed. Optimized loop parameters are obtained by considering the noise reduction and wide dynamic performance of the RFOG. As a result, with the integration time of 10 s, the accuracy of the resonant frequency loop is increased to 0.02 Hz (1σ). It is equivalent to a rotation rate of 0.067°/h, which is close to the shot noise limit for the RFOG, while a minimum rotation of ±0.05°/s has been carried out simultaneously. These are the best results reported to date, to the best of our knowledge, for an RFOG using the miniature semiconductor laser that benefits from the optimization of the resonant frequency servo-loop parameters.

  5. Thermal, structural and optical investigation of Cu-doped ZnO nanoparticles (United States)

    Chithra, Maruthanayagam Jay; Pushpanathan, Kuppusamy


    Well-dispersed undoped and copper-doped zinc oxide nanoparticles (Zn1-xCuxO, x = 0, 1, 5 and 10 wt.%) have been synthesized by precipitation method at room temperature. X-ray diffraction data revealed that the undoped and copper-doped zinc oxide nanoparticles are in phase pure wurtzite structure and the crystallite size increases from 24 nm to 36 nm with increase in dopant concentration. The optical band gap was found to decrease with increasing dopant concentration, which clearly indicates the blue shift. High-resolution scanning electron microscope image shows that the synthesized samples consist of an assembly of nanopetals. Transmission electron microscope image also confirmed the average particle size of 20-50 nm. Energy-dispersive X-ray spectrum shows that the prepared samples are free from impurities. Photoluminescence spectra exposed that copper ions are doped into the lattice positions of ZnO. A simultaneous differential scanning calorimeter/thermogravimetric analysis combination was used to study the phase variations.

  6. Investigation on the Optical and Surface Morphology of Conjugated Polymer MEH-PPV:ZnO Nanocomposite Thin Films

    Directory of Open Access Journals (Sweden)

    Nurul Zayana Yahya


    Full Text Available Thin films of red color poly(2-methoxy-5(2′-ethylhexyloxy-phenylene vinylene (MEH-PPV containing different weight percent of ZnO nanoparticles were obtained by spin-coating techniques. The MEH-PPV:ZnO solutions were spin coated onto silicon and glass substrates. The spun MEH-PPV:ZnO thin films were then used to investigate optical properties by using ultraviolet-visible spectrometer (UV-Vis and photoluminescence spectrophotometer (PL. The morphologies were investigated by using field emission scanning electron microscopy (FESEM, while the identification of ZnO in the final product was determined by using energy-dispersive X-ray spectroscopy (EDS. The UV-Vis absorption band increases, while the optical bandgap decreases when the amount of ZnO nanoparticles increases. ZnO nanoparticles apparently have no effect on the conjugation segments of MEH-PPV. PL spectra show that the emission peak increases and slightly red shift as ZnO concentration increases. Based on SEM images of MEH-PPV:ZnO nanocomposite thin films, ZnO nanoparticles form agglomerated regions.

  7. Quantum dynamics of the Walden inversion reaction Cl - +CH3Cl --> ClCH3+Cl - (United States)

    Clary, David C.; Palma, Juliana


    Quantum scattering calculations on the SN2 reaction Cl-+CH3Cl→ClCH3+Cl- are reported. The rotating bond approximation (RBA) has been adapted so that three degrees of freedom including the C-Cl stretching vibration and the CH3 umbrella mode are treated explicitly. The calculations have been done with minor modifications of a potential due to Vande Linde and Hase. It is found that initial excitation of the C-Cl vibration has a large effect on the reaction probabilities, while excitation of the CH3 umbrella vibration is less significant. The reaction is dominated by scattering resonances with lifetimes ranging from 0.1 to 10 ps. It is found that the length of the C-Cl bond at the transition state of the reaction has a particularly pronounced effect on the reaction probabilities. The magnitude of the quantum reaction probabilities compares quite well with those calculated using the quasiclassical trajectory method.

  8. Investigation of optical and microstructural properties of RF magnetron sputtered PTFE films for hydrophobic applications

    Energy Technology Data Exchange (ETDEWEB)

    Tripathi, S., E-mail: [Optics and Thin Film Laboratory, Bhabha Atomic Research Centre, Visakhapatnam (India); Haque, S. Maidul; Rao, K. Divakar; De, Rajnarayan [Optics and Thin Film Laboratory, Bhabha Atomic Research Centre, Visakhapatnam (India); Shripathi, T.; Deshpande, U.; Ganesan, V. [UGC-DAE Consortium for Scientific Research, Indore (India); Sahoo, N.K. [Atomic and Molecular Physics Division, Bhabha Atomic Research Centre, Mumbai (India)


    Highlights: • Polytetrafluoroethylene films were made by RF sputtering by varying deposition time. • With increasing deposition time, thickness shows unusual trend due to backsputtering. • Major contribution of CF{sub 2} and CF{sub 3} bonds in the samples is seen by ATR-FTIR. • Deposition time influences film thickness but all samples remain hydrophobic. • XPS spectra show strong CF{sub x} bonds at the surface. - Abstract: The deposition time dependence of optical, structural and morphological properties of thin as well as ultrathin Polytetrafluoroethylene (PTFE) sputtered films have been explored in the present communication. The films were prepared by RF magnetron sputtering under high vacuum condition, as a function of deposition time. The ellipsometry as well as X-ray reflectivity data show a drastic reduction in film thickness as the deposition time increases from 5 s to 10 s, possibly as a consequence of back sputtering. With subsequent deposition, back sputtering component decreases and hence, thickness increases with increase in deposition time. Atomic force microscopy (AFM) images show a slight change in growth morphology although roughness is independent of deposition time. Attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) measurements showed the presence of C−C and CF{sub x} (x = 1–3) bonds in all the PTFE films. Supporting this, corresponding X-ray photoelectron spectroscopy (XPS) curves fitted for C-1s and F-1s peaks revealed a major contribution from CF{sub 2} bonds along with significant contribution from CF{sub 3} bonds leading to an F/C ratio of ∼1.5 giving hydrophobic nature of all the films.

  9. The mesospheric sodium layer as a remotely, optically pumped magnetometer for investigation of Birkeland currents (United States)

    Johnsen, Magnar G.; Matzka, Jürgen; Hoppe, Ulf-Peter


    By means of optical pumping, it is possible to use the naturally occurring sodium layer in the mesosphere to measure Earth's scalar magnetic field at ~90 km above ground. This is an altitude not accessible by other means than rockets, which only will provide point measurements of very short time scales. We are planning to modify the sodium lidar at ALOMAR in Northern Norway to be able, for the first time, to measure and monitor the magnetic field in situ in the high latitude mesosphere over longer time scales. The planned modifications to the lidar instrument will allow alternating between the new magnetometer mode and its present mode for atmospheric temperatures and winds. The technique, which has been proposed earlier for measurements at low or mid-latitudes for studies of Earth's internal magnetic field, will in our project be applied to high latitudes in the auroral zone. This opens for a completely new domain of measurements of externally generated geomagnetic variations related to currents in the magnetosphere-ionosphere system. In particular, we aim to measure the magnetic field variations in close vicinity to Birkeland currents associated with particle precipitation events penetrating to altitudes below 90 km and small-scale, discrete auroral arcs. It is, furthermore, anticipated that it will be possible to detect horizontal current structures in the E-layer on much smaller length scales than it is presently possible from ground observations alone. During the project we plan take advantage of the rich space science infrastructure located in northern Norway, including ALOMAR, EISCAT and the Tromsø Geophysical Observatory magnetometer network. If possible, we also aim to make measurements in conjunction with overpasses of the SWARM satellites.

  10. Investigations of Polarization Dependent Loss in Polarization Modulated Analog Optical Links (United States)


    to minimize the 2nd harmonic at -16 dBm input RF power after adding PDL (Black). 10      Fig. 4.2: Curves for 4.1 V bias applied after PDL...Directorate for Information Operations and Reports (0704-0188), 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302. Respondents should be...nonlinearity. Finally, the polarization modulator nonlinearities are investigated, with the results showing the tradeoffs for using either the DC bias of a

  11. Investigation of optical band gap and device parameters of rubrene thin film prepared using spin coating technique

    Energy Technology Data Exchange (ETDEWEB)

    Tuğluoğlu, Nihat, E-mail: [Department of Technology, Sarayköy Nuclear Research and Training Center, 06983 Saray, Ankara (Turkey); Barış, Behzad; Gürel, Hatice [Department of Physics, Faculty of Arts and Sciences, Giresun University, Gazipaşa Campus, Giresun 28100 (Turkey); Karadeniz, Serdar [Department of Technology, Sarayköy Nuclear Research and Training Center, 06983 Saray, Ankara (Turkey); Yüksel, Ömer Faruk [Department of Physics, Faculty of Science, Selçuk University, Campus Konya 42075 (Turkey)


    Highlights: • Thin film of rubrene has been deposited by spin coating technique. • The band gap properties of the film were investigated in the range 200–700 nm. • The analysis of the absorption coefficient revealed indirect allowed transition. • The parameters such as barrier height and ideality factor were determined. -- Abstract: Rubrene thin film has been deposited by spin coating technique. The optical band gap properties of rubrene thin film have been investigated in the spectral range 200–700 nm. The results of the absorption coefficient (α) were analyzed in order to determine the optical band gap and Urbach energy of the film. The absorption spectra recorded in the UV–vis region shows two peaks at 250 nm and 300 nm. The analysis of the spectral behavior of the absorption coefficient (α) in the absorption region revealed indirect allowed transition with corresponding energy 2.31 eV. The value of Urbach energy (E{sub U}) was determined to be 1.169 eV. The current–voltage (I–V) characteristics and electrical conduction properties of rubrene/n-Si device fabricated by spin coating method have also been investigated. The I–V characteristic in dark was showed the rectification effect due to the formation of Schottky barrier at rubrene/silicon interface. From analyzing the I-V measurement for the device, the basic device parameters such as barrier height, ideality factor and series resistance were determined. At the low-voltage region, the current conduction in Au/rubrene/n-Si device is ohmic type. The charge transport phenomenon appears to be space charge limited current (SCLC) at higher-voltage regions.

  12. Highly spatially resolved structural and optical investigation of Bi nanoparticles in Y-Er disilicate thin films (United States)

    Scarangella, A.; Amiard, G.; Reitano, R.; Priolo, F.; Boninelli, S.; Miritello, M.


    Er-containing silicon compatible materials have been widely used as infrared emitters for microphotonics application. In this field, the additional introduction of a proper sensitizer permits to increase the Er excitation cross sections, thus increasing its optical efficiency. This work aims to investigate the influence of a post-transition metal, bismuth, on the optical properties of erbium-yttrium disilicate thin films synthesized by magnetron co-sputtering. After thermal treatments at 1000 °C in O2 or N2 environment, the presence of small precipitates, about 6 nm in diameter, was evidenced by transmission electron microscopy analyses. The spatially resolved chemical nature of the nanoparticles was discerned in the Si and O rich environments by means of scanning transmission electron microscopy-energy dispersive X-ray and scanning transmission electron microscopy-electron energy loss spectroscopy analyses performed with nanometric resolution. In particular, metallic Bi nanoparticles were stabilized in the N2 environment, being strongly detrimental for the Er emission. A different scenario was instead observed in O2, where the formation of Bi silicate nanoparticles was demonstrated with the support of photoluminescence excitation spectroscopy. In particular, a broad band peaked at 255 nm, correlated to the excitation band of Bi silicate nanoparticles, was identified in Er excitation spectrum. Thus Bi silicate clusters act as sensitizer for Er ions, permitting to improve Er emission up to 250 times with respect to the resonant condition. Moreover, the Er decay time increases in the presence of the Bi silicate nanoparticles that act as cages for Er ions. These last results permit to further increase Er optical efficiency in the infrared range, suggesting (Bi + Er)-Y disilicate as a good candidate for applications in microphotonics.

  13. Comparative investigation of optical techniques for topography measurement of rough plastic surfaces

    DEFF Research Database (Denmark)

    Bariani, Paolo; Hansen, Hans Nørgaard; Arlø, Uffe Rolf


    polypropylene parts manufactured by injection moulding. The mould was equipped with inserts with EDM machined surfaces (Sa  3.5 µm) in order to represent a typical tool surface for injection moulding. A focus detection laser scanning profiler, a confocal scanning laser microscope, a white light interferometer...... and, in addition, a scanning electron microscope, have been used in the analysis of plastic surfaces. This investigation has shown that topography assessment of rough plastic surfaces is critical to both white light interference microscope and confocal microscope while the focus detection laser...

  14. Investigation of the optical properties of novel organic macromolecules for solar cell applications (United States)

    Adegoke, Oluwasegun Oluwasina

    The search for renewable energy sources to replace fossil fuel has been a major research focus in the energy sector. The sun, with its vast amount of energy, remains the most abundant and ubiquitous energy source that far exceeds the world energy demand. The ability to effectively capture and convert energy from the sun in the form of photons will be the key to its effective utilization. Organic macromolecules have tremendous potentials to replace and out-perform existing materials, due to their low-cost, ease of tunability, high absorption coefficient and "green" nature. In this dissertation, spectroscopic techniques of steady state absorption and time-resolved fluorescence spectroscopy were used to show the improved absorption of the oligothiophene-functionalized ZnPc through ultrafast energy transfer. ZnPc is known for its chemical and thermal stability. The power conversion efficiency (PCE) in ZnPc-based solar devices is however, very low because of the poor absorption of ZnPc in the 300 - 550 nm region of the solar spectrum. Oligothiophenes have good absorption in the spectral region where the absorption of ZnPc is poor. Other groups of organic compounds that have gained prominence in the study for the design of efficient active materials for photovoltaic cells are the polymers. In the dissertation, different factors which can affect the performance of organic polymers in photovoltaics systems were investigated and analyzed. The effects of the alteration of conjugation, donor-acceptor groups, heteroatoms and alkyl side chains on the photophysical properties and ultimately the performance of organic polymers in organic photovoltaics were investigated. The different effects were investigated using ultrafast spectroscopic techniques which are capable of providing insight of fluorescence decay dynamics at very short times in a time scale of femtosecond. The electronic structure calculations of the polymers were carried out to provide further evidence to the

  15. Investigations into the feasibility of optical-CT 3D dosimetry with minimal use of refractively matched fluids

    Energy Technology Data Exchange (ETDEWEB)

    Chisholm, Kelsey; Miles, Devin [Medical Physics Graduate Program, Duke University, Durham, North Carolina 27710 (United States); Rankine, Leith [Department of Radiation Oncology, Washington University School of Medicine, St. Louis, Missouri 63110 (United States); Oldham, Mark, E-mail: [Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina 27710 (United States)


    Purpose: In optical-CT, the use of a refractively matched polyurethane solid-tank in place of a fluid bath has the potential to greatly increase practical convenience, reduce cost, and possibly improve the efficacy of flood corrections. This work investigates the feasibility of solid-tank optical-CT imaging for 3D dosimetry through computer simulation. Methods: A MATLAB ray-tracing simulation platform, ScanSim, was used to model a parallel-source telecentric optical-CT imaging system through a polyurethane solid-tank containing a central cylindrical hollow into which PRESAGE radiochromic dosimeters can be placed. A small amount of fluid fills the 1–5 mm gap between the dosimeter and the walls of the tank. The use of the solid-tank reduces the required amount of fluid by approximately 97%. To characterize the efficacy of solid-tank, optical-CT scanning simulations investigated sensitivity to refractive index (RI) mismatches between dosimeter, solid-tank, and fluid, for a variety of dosimeter (RI = 1.5–1.47) and fluid (RI = 1.55–1.0) combinations. Efficacy was evaluated through the usable radius (r{sub u}) metric, defined as the fraction of the radius of the dosimeter where measured dose is predicted to be within 2% of the ground truth entered into the simulation. Additional simulations examined the effect of increasing gap size (1–5 mm) between the dosimeter and solid-tank well. The effects of changing the lens tolerance (0.5°–5.0°) were also investigated. Results: As the RI mismatch between the dosimeter and solid-tank increased from 0 to 0.02, the usable radius decreased from 97.6% to 50.2%. The optimal fluid RI decreased nonlinearly from 1.5 to 1.34 as the mismatch increased and was up to 9% lower than the tank. Media mismatches between the dosimeter and solid-tank also exacerbate the effects of changing the gap size, with no easily quantifiable relationship with usable radius. Generally, the optimal fluid RI value increases as gap size increases and

  16. Optical and analytical investigations on dengue virus rapid diagnostic test for IgM antibody detection. (United States)

    Jahanshahi, Peyman; Sekaran, Shamala Devi; Adikan, Faisal Rafiq Mahamd


    Evaluation of binding between analytes and its relevant ligands on surface plasmon resonance (SPR) biosensor is of considerable importance for accurate determination and screening of an interference in immunosensors. Dengue virus serotype 2 was used as a case study in this investigation. This research work compares and interprets the results obtained from analytical analysis with the experimental ones. Both the theoretical calculations and experimental results are verified with one sample from each category of dengue serotypes 2 (low, mid, and high positive), which have been examined in the database of established laboratorial diagnosis. In order to perform this investigation, the SPR angle variations are calculated, analyzed, and then validated via experimental SPR angle variations. Accordingly, the error ratios of 5.35, 6.54, and 3.72% were obtained for the low-, mid-, and high-positive-specific immune globulins of patient serums, respectively. In addition, the magnetic fields of the biosensor are numerically simulated to show the effect of different binding mediums.

  17. Synthesis Al complex and investigating effect of doped ZnO nanoparticles in the electrical and optical efficiency of OLEDS (United States)

    Shahedi, Zahra; Jafari, Mohammad Reza


    In this study, an organometallic complex based on aluminum ions is synthesized. And it is utilized as fluorescent material in the organic light-emitting diodes (OLEDs). The synthesized complex was characterized using XRD, UV-Vis, FT-IR as well as PL spectroscopy analyses. The energy levels of Al complex were determined by cyclic voltammetry measurements. Then, the effects of ZnO nanoparticles (NPs) of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate), PEDOT:PSS, on the electrical and optical performance of the organic light-emitting diodes have been investigated. For this purpose, two samples containing ITO/PEDOT:PSS/PVK/Alq3/PBD/Al with two different concentration and two samples containing ITO/PEDOT:PSS:ZnO/PVK/Alq3/PBD/Al with two different concentration were prepared. Then, hole transport, electron transport and emissive layers were deposited by the spin coating method and the cathode layer (Al) was deposited by the thermal evaporation method. The OLED simulation was also done by constructing the model and choosing appropriate parameters. Then, the experimental data were collected and the results interpreted both qualitatively and quantitatively. The results of the simulations were compared with experimental data of the J-V spectra. Comparing experimental data and simulation results showed that the electrical and optical efficiency of the samples with ZnO NPs is appreciably higher than the samples without ZnO NPs.

  18. Design and theoretical investigation of a silicon-on-insulator based electro-optical logic gate device (United States)

    Li, Lei; Qi, Zhipeng; Hu, Guohua; Yun, Binfeng; Zhong, Yuan; Cui, Yiping


    A compact electro-optical "NOR" logic gate device based on silicon-on-insulator (SOI) platform is proposed and investigated theoretically. By introducing a hook-type waveguide, the signal could be coupled between the bus and hook-type waveguide to form an optical circuit and realize NOR logic gate. We can easily realize the NOR logical function by the voltage applied on the coupling components. The numerical simulation shows that a high coupling efficiency of more than 99% is obtained at the wavelength of 1550 nm, and the footprint of our device is smaller than 90 μm2. In addition, the response time of the proposed NOR logic gate is 3 ns with a switching voltage of 1.8 V. Moreover, it is demonstrated that such NOR logic gate device could obtain an extinction ratio of 21.8 dB. Thus, it has great potential to achieve high speed response, low power consumption, and small footprint, which fulfill the demands of next-generation on-chip computer multiplex processors.

  19. Investigation on nonlinear optical and dielectric properties of L-arginine doped ZTC crystal to explore photonic device applications

    Directory of Open Access Journals (Sweden)

    Anis Mohd


    Full Text Available The present study is focused to explore the photonic device applications of L-arginine doped ZTC (LA-ZTC crystals using nonlinear optical (NLO and dielectric studies. The LA-ZTC crystals have been grown by slow evaporation solution technique. The chemical composition and surface of LA-ZTC crystal have been analyzed by means of energy dispersive spectroscopy (EDS and surface scanning electron microscopy (SEM techniques. The Vicker’s microhardness study has been carried out to determine the hardness, work hardening index, yield strength and elastic stiffness of LA-ZTC crystal. The enhanced SHG efficiency of LA-ZTC crystal has been ascertained using the Kurtz-Perry powder SHG test. The closed-and-open aperture Z-scan technique has been employed to confirm the third order nonlinear optical nature of LA-ZTC crystal. The Z-scan transmittance data has been utilized to calculate the superior cubic susceptibility, nonlinear refractive index, nonlinear absorption coefficient and figure of merit of LA-ZTC crystal. The behavior of dielectric constant and dielectric loss of LA-ZTC crystal at different temperatures has been investigated using the dielectric analysis.

  20. (enH2)(4.5)[In(As(V)S4)3][As2(III)(μ-S2)S3]Cl and (enH2)MnAs(III)As(V)S6: two thioarsenates(III, V) with mixed-valent optical properties. (United States)

    Du, Ke-Zhao; Feng, Mei-Ling; Qi, Xing-Hui; Ma, Zu-Ju; Li, Long-Hua; Li, Jian-Rong; Du, Cheng-Feng; Zou, Guo-Dong; Huang, Xiao-Ying


    Two mixed-valent thioarsenates, namely (enH2)(4.5)[In(As(V)S4)3][As2(III)(μ-S2)S3]Cl (1) and (enH2)MnAs(III)As(V)S6 (2) (en = ethylenediamine), have been solvothermally synthesized and characterized. Thermal stability, magnetic and mixed-valent optical properties, as well as theoretical band structures and DOSs, of 1 and 2 have also been studied.

  1. Numerous possible oriented partial differential equations and investigation of their performance for optical interferometry fringes denoising. (United States)

    Mi, Qinghua; Yan, Si; Tang, Chen


    Filtering methods based on oriented partial differential equations (OPDEs) have been demonstrated as a powerful tool for denoising while preserving all fringes. In this paper, we first briefly review the existing OPDEs and then derive numerous possible OPDE filtering models based on the variational methods. These models include a class of new single OPDE models, a class of new selective OPDE models, a class of new coupled OPDEs, and a class of new double OPDEs. We also investigate the performance of main OPDE models, including the choices of parameters and the influences of fringe orientation and diffusion control function on filtering results via our extensive experiments. Finally, we summarize the performance of these OPDEs.

  2. Investigation of Electron Transfer-Based Photonic and Electro-Optic Materials and Devices

    Energy Technology Data Exchange (ETDEWEB)

    Bromenshenk, Jerry J; Abbott, Edwin H; Dickensheets, David; Donovan, Richard P; Hobbs, J D; Spangler, Lee; McGuirl, Michele A; Spangler, Charles; Rebane, Aleksander; Rosenburg, Edward; Schmidt, V H; Singel, David J


    Montana's state program began its sixth year in 2006. The project's research cluster focused on physical, chemical, and biological materials that exhibit unique electron-transfer properties. Our investigators have filed several patents and have also have established five spin-off businesses (3 MSU, 2 UM) and a research center (MT Tech). In addition, this project involved faculty and students at three campuses (MSU, UM, MT Tech) and has a number of under-represented students, including 10 women and 5 Native Americans. In 2006, there was an added emphasis on exporting seminars and speakers via the Internet from UM to Chief Dull Knife Community College, as well as work with the MT Department of Commerce to better educate our faculty regarding establishing small businesses, licensing and patent issues, and SBIR program opportunities.

  3. Molecular Investigation of Leber’s Hereditary Optic Neuropathy Common Mutations in Suspected Patients

    Directory of Open Access Journals (Sweden)

    HR Soleimanpour


    Full Text Available LHON is a mitochondrial neurodegenerative disorder often manifesting itself in the second or third decade of life, and hence resulting in progressive central vision loss usually in a short period of 2-8 weeks within which different degrees of blindness may occur. Etiologically, more than twenty missense mutations have been reported for LHON, amongst which the three mutations of G11778A, G3460A and T14484C, affecting NADH dehydrogenase complex activity, are recognized as primary mutations. The three primary mutations account for 90% of LHON patients, emphasizing the importance of molecular investigation of these mutations for differential diagnosis of LHON. Using PCR-RFLP, this research resulted in the detection of two LHON families carrying the G11778A mutation in homoplasmy and described the clinical and molecular features of the disease in the patients.

  4. Experimental Investigation on Transmission Control Protocol Throughput Behavior in Optical Fiber Access Networks (United States)

    Tego, Edion; Matera, Francesco; del Buono, Donato


    This article describes an experimental investigation on the behavior of transmission control protocol in throughput measurements to be used in the verification of the service-level agreement between the Internet service provider and user in terms of line capacity for ultra-broadband access networks typical of fiber-to-the-x architectures. It is experimentally shown different conditions in high bandwidth-delay product links where the estimation of the line capacity based on a single transmission control protocol session results are unreliable. Simple equations reported in this work, and experimentally verified, point out the conditions in terms of packet loss, time delay, and line capacity, that allow consideration of the reliability of the measurement carried out with a single transmission control protocol session test by adopting a suitable measurement time duration.

  5. In situ optical microscopy investigations of lithium and sodium film formation in buffered room temperature molten salts

    Energy Technology Data Exchange (ETDEWEB)

    Fuller, J.; Carlin, R.T. [Covalent Associates, Incorporated, Woburn, MA (United States); Osteryoung, R.A. [North Carolina State Univ., Raleigh, NC (United States). Dept. of Chemistry


    Previous work performed in both sodium and lithium buffered chloroaluminate molten salts have shown that the addition of small amounts of SOCl{sub 2} promotes the reversible stripping behavior of lithium and sodium metal with cycling efficiencies between 80 and 90%. The authors have performed a series of optical studies in conjunction with electrochemical experiments at varying SOCl{sub 2} concentrations in both lithium and sodium chloride buffered melts. On investigation, the lithium deposit is dendritic in nature and does not form a uniform film on the tungsten electrode. After discharging at moderate current densities, disconnected lithium metal is observed at the electrode surface. In contrast, the sodium deposits as a uniform, flat film on the tungsten electrode with little or no dendritic growth. The sodium electrodeposits undergo complete stripping from the tungsten electrode without dendritic or disconnected sodium metal left on the electrode surface.

  6. Pump and probe damage testing for investigation of transient material modifications associated with laser damage in optical materials

    Energy Technology Data Exchange (ETDEWEB)

    Negres, R A; Feit, M D; DeMange, P; Bude, J D; Demos, S G


    Laser-induced breakdown in the bulk of transparent dielectric materials is associated with the generation of extreme localized conditions of temperatures and pressures. In this work, we perform pump and probe damage testing experiments to investigate the evolution of transient absorption by the host material arising from modifications following confined laser energy deposition in fused silica and DKDP materials. Specifically, we measure the size of the damage sites observed in the region of spatial overlap between the pump and probe pulses versus probe time delay and energy. Results of this proof-of-principle experimental work confirm that material modifications under extreme conditions created during a damage event include transient optical absorption. In addition, we found that the relaxation times of the induced absorption are very distinct for DKDP and SiO{sub 2} even under identical excitation conditions, on the order of 100 ns and 100 {micro}s, respectively.

  7. Theoretical investigations of the optical and EPR spectra for trivalent cerium and ytterbium ions in orthorhombic YF3 crystal (United States)

    Liu, Hong-Gang; Zheng, Wen-Chen


    The optical spectra and electron paramagnetic resonance (EPR) parameters (g factors and hyperfine structure constants A) for trivalent cerium and ytterbium ions in YF3 crystal with orthorhombic structure are investigated together by the complete diagonalization (of energy matrix) method (CDM). The obtained results are in reasonable agreement with the experimental ones. More importantly, two magnetically nonequivalent centers in YF3 crystal observed in EPR experiments are confirmed and ascribed to their specific positions in a unit cell by our calculations based on superposition model (SPM) analysis. Such identification of local sites with different magnetic properties would help us to understand not only the EPR spectra and magnetic susceptibility of other lanthanide ions doped in crystals with the same structure as YF3 but also the energy transfer scheme between two lanthanide ions occupying such two sites. All results are discussed carefully.

  8. Non-contact investigation of the corneal biomechanics with air-puff swept source optical coherence tomography (United States)

    Maczynska, Ewa; Karnowski, Karol; Kaluzny, Bartlomiej; Grulkowski, Ireneusz; Wojtkowski, Maciej


    In this paper, we use swept source optical coherence tomography combined with air-puff module (air-puff SS-OCT) to investigate the properties of the cornea. During OCT measurement the cornea was stimulated by short, air pulse, and corneal response was recorded. In this preliminary study, the air-puff SS-OCT instrument was applied to measure behavior of the porcine corneas under varied, well-controlled intraocular pressure conditions. Additionally, the biomechanical response of the corneal tissue before, during and after crosslinking procedure (CXL) was assessed. Air-puff swept source OCT is a promising tool to extract information about corneal behavior as well as to monitor and assess the effect of CXL.

  9. Temperature-Dependent Effects of FeS2 Thin Film Synthesized by Thermochemical Spraying: An Optical and Physicochemical Investigation (United States)

    Kao, Chia-Tze; Shi, Jen-Bin; Lee, Hsuan-Wei; Cheng, Fu-Chou; Liu, Hung-Hsin; Lee, Ming-Way; Chan, Chih-Chieh; Huang, Chien-Wei; Lin, Hsien-Sheng; Wu, Po-Feng; Chen, Chin-Yi; Kao, Ming-Cheng; Young, San-Lin; Lin, Cheng-Li


    FeS2 pyrite films are used in a variety of applications including solar cells and, the potential scope for their utilization is increasing as their synthetic methods become more economical while maintaining or enhancing their high light absorption coefficients. The glass substrate temperature dependence on the formation of FeS2 pyrite films was investigated with respect to their optical and physicochemical properties. During the thermochemical spraying process the temperature was varied in the range of 190-290 °C. FeS2 nanocrystalline (40-70 nm) films, formed as a result of atmospheric spraying with glass substrate temperatures above 260 °C, were observed by SEM. Opto-electronic studies revealed that the nanocrystalline films had a direct band gap (1.3-1.6 eV) with a high light absorption coefficient (α > 7 × 104 cm-1 for λ application as high light-absorbing solar energy absorbers.

  10. Optical and Structural Investigation of CdSe Quantum Dots Dispersed in PVA Matrix and Photovoltaic Applications

    Directory of Open Access Journals (Sweden)

    Pallabi Phukan


    Full Text Available CdSe quantum dots (QDs dispersed in polyvinyl alcohol (PVA matrix with their sizes within the quantum dot regime have been synthesized via a simple heat induced thermolysis technique. The effect of the concentrations of the cadmium source on the optical properties of CdSe/PVA thin films was investigated through UV-Vis absorption spectroscopy. The structural analysis and particle size determination as well as morphological studies of the CdSe/PVA nanocomposite thin films were done with the help of X-ray diffraction (XRD and transmission electron microscopy (TEM. The XRD analysis reveals that CdSe/PVA nanocomposite thin film has a hexagonal (wurtzite structure. A prototype thin film solar cell of CdSe/CdTe has been synthesized and its photovoltaic parameters were measured.

  11. Experimental investigation of PAM, CAP and DMT modulations efficiency over a double-step-index polymer optical fiber (United States)

    Stepniak, G.; Siuzdak, J.


    Investigated was the transmission over step index POF that is 50 m/100 m long with a red DVD laser as a source and a Si p-i-n commercial photo-detector. The maximum bit rates of three modulation formats: PAM, CAP and DMT were sought. Their constellation sizes and symbol rates were varied in order to maximize FEC limited throughputs for each modulation whereas the laser operating point and relevant optical powers were maintained constant for all the modulations. The maximum throughputs were similar for PAM and CAP, namely 3.3/2 Gbit/s for PAM, and 3.15/2.1 for CAP for 50/100 m fiber, respectively. The bit rates for DMT were 2.65/1.65 Gbit/s for the respective lengths of the fiber. We attribute the inferior performance of DMT to its high value of peak to average power ratio.

  12. Theoretical Investigation of the Optical Spectra of Organic Compounds in Natural Surrounding (United States)

    Pomogaev, V. A.; Artyukhov, V. Ya.


    The hybrid multiscale approximation based on molecular dynamics, quantum mechanics, and statistical theory is used to generate profiles of electronic vibrational absorption and fluorescence bands of some organic compounds and biological objects whose photophysical properties specifically depend on external conditions. A temperature dependence of the spectrum width and intensity of transition to the long-wavelength band of benzene surrounded by cyclohexane molecules is demonstrated. Statistical broadband absorption spectra for estradiol in ethanol, hexane, and dimethyl sulfoxide have been obtained and analyzed at room temperature together with a wide spectrum of transitions to numerous excited states of Trp-cage miniprotein. The absorption and emission spectra of 9-cyan anthracene have been generated under various thermodynamic conditions. This allows changes in the spectral profile with increasing temperatures and pressure to be detected. A dependence of the tryptophan spectra on the protein microsurrounding is investigated. The possibility of charge transfer from tryptophan residue to the eupatorin molecule trapped by human serum albumin is analyzed. Spectral properties and charge transfer from the excited donor to acceptor states are calculated using the polarizable embedding approach for modeling of surrounding protein structure.

  13. Comparative investigation of hydrogen bonding in silicon based PECVD grown dielectrics for optical waveguides (United States)

    Ay, F.; Aydinli, A.


    Silicon oxide, silicon nitride and silicon oxynitride layers were grown by a PECVD technique. The resulting refractive indices of the layers varied between 1.47 and 1.93. The compositional properties of the layers were analyzed by FTIR and ATR infrared spectroscopy techniques. Comparative investigation of bonding structures for the three different layers was performed. Special attention was given to analyze N-H bond stretching absorption at 3300-3400 cm -1. Quantitative results for hydrogen related bonding concentrations are presented based on IR analysis. An annealing study was performed in order to reduce or eliminate this bonding types. For the annealed samples the N-H bond concentration was strongly reduced as verified by FTIR transmittance and ATR spectroscopic methods. A correlation between the N-H concentration and absorption loss was verified for silicon oxynitride slab waveguides. Moreover, a single mode waveguide with silicon oxynitride core layer was fabricated. Its absorption and insertion loss values were determined by butt-coupling method, resulting in low loss waveguides.

  14. Synthesis of a new π-conjugated redox oligomer: Electrochemical and optical investigation (United States)

    Blili, Saber; Zaâboub, Zouhour; Maaref, Hassen; Haj Said, Ayoub


    A new π-conjugated redox oligomer was prepared according a two-Step Synthesis. Firstly, an oligophenylene (OMPA) was obtained from the anodic oxidation of the (4-methoxyphenyl)acetonitrile. Then, the resulting material was chemically modified by the Knoevenagel condensation with the ferrocenecarboxaldehyde. This reaction led to a redox-conjugated oligomer the Fc-OMPA. The synthesized material was characterized using different spectroscopic techniques: NMR, FTIR, UV-vis and photoluminescence (PL) spectroscopy. The Fc-OMPA was used to modify a platinum electrode surface and the electrochemical response of the ferrocene redox-center was investigated by cyclic voltammetry. Moreover, the room temperature PL spectra of Fc-OMPA revealed that the ferrocene moiety, which acts as an electron donor, can effectively quench the oligomer luminescence. However, when ferrocene was oxidized to ferrocenium ion, the intramolecular charge transfer process was prevented which consequently enhanced the light emission. Thus, the oligomer light-emission can be, chemically or electrochemically tuned. The obtained results showed that the prepared material is a good candidate for the elaboration of electrochemical sensors and for the development of luminescent Redox-switchable devices.

  15. Investigation of optical and electrical properties of amorphous Se95-xSxZn5(x=0.2, 2, 5 and 10) thin films (United States)

    Nasir, Mohd.; Ahmad, Shabir; Zulfequar, M.


    In this study, we reported that the optical and electrical analysis of amorphous Se90-xSxZn5 (x=0.2, 2, 5, 10) thin films. Bulk samples of the investigated material were prepared by melt quenching technique. Thin films of ~ 300nm thickness were deposited on cleaned glass substrates by thermal evaporation technique. The morphological study of the investigated material in powder form carried out by scanning electron microscopy (SEM) confirms the disorder of the material increases at lower sulfur doping (up to 5%) whereas at higher (S) doping (10%) the defects of the material decreases. The optical parameters were estimated from optical absorption spectra data measured from UV-Vis-spectrophotometer in the wavelength range 200-900 nm. It was found that the value of optical band gap (Eg) of the investigated thin films decreases up to lower S doping and increases at higher (S) doping. The other optical parameters such as absorption coefficient (α) and extinction coefficient (K) increases up to lower S doping and decreases at higher S doping. This remarkable change in the values of optical parameters was interpreted on the basis of model proposed by Davis and Mott. Electrical parameters of the investigated thin films were carried out in the temperature range 309-370 K. Analysis of data shows activation energy decreases with the increase of concentration of (S) increases up to 5% and at 10% it increases again.

  16. Investigation on Dynamic Calibration for an Optical-Fiber Solids Concentration Probe in Gas-Solid Two-Phase Flows


    Changsui Zhao; Liu Shen; Pan Xu; Xiaoping Chen; Daoyin Liu; Cai Liang; Guiling Xu


    This paper presents a review and analysis of the research that has been carried out on dynamic calibration for optical-fiber solids concentration probes. An introduction to the optical-fiber solids concentration probe was given. Different calibration methods of optical-fiber solids concentration probes reported in the literature were reviewed. In addition, a reflection-type optical-fiber solids concentration probe was uniquely calibrated at nearly full range of the solids concentration from 0...

  17. Structural and optical investigation of InAsxP1-x/InP strained superlattices (United States)

    Lamberti, C.; Bordiga, S.; Boscherini, F.; Mobilio, S.; Pascarelli, S.; Gastaldi, L.; Madella, M.; Papuzza, C.; Rigo, C.; Soldani, D.; Ferrari, C.; Lazzarini, L.; Salviati, G.


    We report a complete characterization of InAsxP1-x/InP (0.05investigation we characterize not only very high quality heterostructures but also samples showing serious interface problems such as nonplanarity and/or a consistent chemical spread along the growth axis. In the study presented here we thus propose a general method, based on

  18. 离子液体[ bmim] Cl/AlCl3催化5-氰基吲哚酰化反应%Acylation of 5-cyanoindole catalyzed by ionic liquid[ bmim] Cl/AlCl3

    Institute of Scientific and Technical Information of China (English)



    5-氰基吲哚与4-氯丁酰氯之间的傅-克酰化反应使用路易斯酸之类的催化剂(如AlCl3、FeCl3),反应产物复杂,无法分离出期望的产物5-氰基-3-(4-氯丁酰基)吲哚。在离子液体[bmim]Cl/AlCl3中,进行5-氰基吲哚与4-氯丁酰氯间的傅-克酰化反应,则反应的主产物是5-氰基-3-(4-氯丁酰基)吲哚,产物结构通过质谱与核磁共振氢谱表征。考察了[ bmim] Cl/AlCl3中AlCl3与[ bmim] Cl间的摩尔比以及[ bmim] Cl/AlCl3与5-氰基吲哚的摩尔比对该酰化反应的影响。结果表明,当n(AlCl3)∶n([bmim]Cl)=2.5∶1,n([bmim]Cl/AlCl3)∶n (5-氰基吲哚)=2∶1,室温下反应24 h,最大产率71.7%。%The product of Friedel-Crafts acylation reaction between 5-cyanoindole and 4-chlorobutyryl chloride used AlCl3 as catalyst was complicated,so that no 5-cyano-3-(4-chlorobutanoyl)indole could be isolated. The same reaction was conducted in 1-butyl-3-methylimidazolium chloroaluminate([bmim] Cl/AlCl3 ),the major product was 5-cyano-3-(4-chlorobutanoyl) indole. Its structure was characterized by Mass and 1 H NMR. The effects of the molar rations of AlCl3 to[ bmim] Cl in[ bmim] Cl/AlCl3 and the molar ra-tio of[ bmim] Cl/AlCl3 to 5-cyanoindole on the acylation reaction were investigated. The results showed that suitable molar ratios of AlCl3 to[bmim]Cl in[bmim]Cl/AlCl3 were between 2. 5∶1,the molar ratio of[bmim]Cl/AlCl3 to 5-cyanoindole was 2∶1,reacting at room temperature for 24h,a good yield was obtained 71. 7%.

  19. Impact of intraocular pressure on changes of blood flow in the retina, choroid, and optic nerve head in rats investigated by optical microangiography


    Zhi, Zhongwei; Cepurna, William O.; Johnson, Elaine C.; Morrison, John C.; Wang, Ruikang K.


    In this paper, we demonstrate the use of optical coherence tomography/optical microangiography (OCT/OMAG) to image and measure the effects of acute intraocular pressure (IOP) elevation on retinal, choroidal and optic nerve head (ONH) perfusion in the rat eye. In the experiments, IOP was elevated from 10 to 100 mmHg in 10 mmHg increments. At each IOP level, three-dimensional data volumes were captured using an ultrahigh sensitive (UHS) OMAG scanning protocol for 3D volumetric perfusion imaging...

  20. Ultrafast electron, lattice and spin dynamics on rare earth metal surfaces. Investigated with linear and nonlinear optical techniques

    Energy Technology Data Exchange (ETDEWEB)

    Radu, I.E.


    This thesis presents the femtosecond laser-induced electron, lattice and spin dynamics on two representative rare-earth systems: The ferromagnetic gadolinium Gd(0001) and the paramagnetic yttrium Y(0001) metals. The employed investigation tools are the time-resolved linear reflectivity and second-harmonic generation, which provide complementary information about the bulk and surface/interface dynamics, respectively. The femtosecond laser excitation of the exchange-split surface state of Gd(0001) triggers simultaneously the coherent vibrational dynamics of the lattice and spin subsystems in the surface region at a frequency of 3 THz. The coherent optical phonon corresponds to the vibration of the topmost atomic layer against the underlying bulk along the normal direction to the surface. The coupling mechanism between phonons and magnons is attributed to the modulation of the exchange interaction J between neighbour atoms due to the coherent lattice vibration. This leads to an oscillatory motion of the magnetic moments having the same frequency as the lattice vibration. Thus these results reveal a new type of phonon-magnon coupling mediated by the modulation of the exchange interaction and not by the conventional spin-orbit interaction. Moreover, we show that coherent spin dynamics in the THz frequency domain is achievable, which is at least one order of magnitude faster than previously reported. The laser-induced (de)magnetization dynamics of the ferromagnetic Gd(0001) thin films have been studied. Upon photo-excitation, the nonlinear magneto-optics measurements performed in this work show a sudden drop in the spin polarization of the surface state by more than 50% in a <100 fs time interval. Under comparable experimental conditions, the time-resolved photoemission studies reveal a constant exchange splitting of the surface state. The ultrafast decrease of spin polarization can be explained by the quasi-elastic spin-flip scattering of the hot electrons among spin

  1. In vivo investigation of temporal effects and drug delivery induced by transdermal microneedles with optical coherence tomography (United States)

    Tsai, Meng-Tsan; Lee, I-Chi; Lee, Zhung-Fu; Liu, Hao-Li; Wang, Chun-Chieh; Choia, Yo-Chun; Chou, Hsin-Yi; Lee, Jiann-Der


    Transdermal drug-delivery systems (TDDS) have been a growing field in drug delivery because of their advantages over parenteral and oral administration. Recent studies illustrate that microneedles (MNs) can effectively penetrate through the stratum corneum barrier to facilitate drug delivery. However, the temporal effects on skin and drug diffusion are difficult to investigate in vivo. In this study, we used optical coherence tomography (OCT) to observe the process by which MNs dissolve and to investigate the temporal effects on mouse skin induced by MNs, including the morphological and vascular changes. Moreover, the recovery process of the skin was observed with OCT. Additionally, we proposed a method to observe drug delivery by estimation of cross-correlation relationship between sequential 2D OCT images obtained at the same location, reflecting the variation in the backscattered intensity due to the diffusion of the rhodamine molecules encapsulated in MNs. Our observations supported the hypothesis that the temporal effects on skin due to MNs, the dissolution of MNs, and the drug diffusion process can be quantitatively evaluated with OCT. The results showed that OCT can be a potential tool for in vivo monitoring of effects and outcomes when MNs are used as a TDDS. PMID:27231627

  2. Investigation the optical and radiative properties of aerosol vertical profile of boundary layer by lidar and ground based measurements (United States)

    Chen, W.; Chou, C.; Lin, P.; Wang, S.


    The planetary boundary layer is the air layer near the ground directly affected by diurnal heat, moisture, aerosol, and cloud transfer to or from the surface. In the daytime solar radiation heats the surface, initiating thermal instability or convection. Whereas, the scattering and absorption of aerosols or clouds might decrease the surface radiation or heat atmosphere which induce feedbacks such as the enhanced stratification and change in relative humidity in the boundary layer. This study is aimed to understand the possible radiative effect of aerosols basing on ground based aerosol measurements and lidar installed in National Taiwan University in Taipei. The optical and radiative properties of aerosols are dominated by aerosol composition, particle size, hygroscopicity property, and shape. In this study, aerosol instruments including integrating nephelometer, open air nephelometer, aethalometer are applied to investigate the relationship between aerosol hygroscopicity properties and aerosol types. The aerosol hygroscopicity properties are further applied to investigate the effect of relative humidity on aerosol vertical profiles measured by a dual-wavelength and depolarization lidar. The possible radiative effect of aerosols are approached by vertical atmospheric extinction profiles measured by lidar. Calculated atmospheric and aerosol heating effects was compared with vertical meteorological parameters measured by radiosonde. The result shows light-absorbing aerosol has the potential to affect the stability of planetary boundary layer.

  3. Investigation of optical, photocatalytic and physical adsorption of a new nanocomposite synthesized via a simple co-precipitation method (United States)

    Sabet, Mohammad; Mohammadi, Marziyeh; Googhari, Fatemeh


    In this experimental work, different morphologies of the CdxZn1-xS/ZnO nanocomposite were synthesized via a simple co-precipitation method. The effect of Zn2+: Cd2+ mole ratio on the product size and morphology was investigated and it was found that the mole ratio has a significant effect on the morphology of the products. To study the crystallinity and purity of the product, X-ray diffraction (XRD) pattern was served. Scanning electron microscopy (SEM) was used to study the morphology of the products. The optical properties of the as-synthesized nanocomposites were studied by ultraviolet-visible (UV-Vis) spectra. Photocatalytic activity of the nanocomposite was carried out by decomposition of Acid Black 1 dye, and it was found after 60min, almost all the dye structure was decomposed under UV radiation. Finally, to study the nanocomposite performance in removing heavy metal ions from water, three different solutions containing Zn2+, Cd2+ and Pb2+ with 0.01 molar concentration were prepared in the aqueous medium and the absorption of them with the nanocomposite was investigated by atomic absorption spectroscopy (AAS). The results showed that the synthesized nanocomposite has a unique performance and it can remove almost 80% of heavy metal ions from the water.

  4. Ab-initio investigation of structural, electronic and optical properties BSb compound in bulk and surface (110 states

    Directory of Open Access Journals (Sweden)

    H A Badehian


    Full Text Available In recent work the structural, electronic and optical properties of BSb compound in bulk and surface (110 states have been studied. Calculations have been performed using Full-Potential Augmented Plane Wave (FP-LAPW method by WIEN2k code in Density Functional Theory (DFT framework. The structural properties of the bulk such as lattice constant, bulk module and elastic constants have been investigated using four different approximations. The band gap energy of the bulk and the (110 surface of BSb were obtained about 1.082 and 0.38 eV respectively. Moreover the surface energy, the work function, the surface relaxation, surface state and the band structure of BSb (110 were investigated using symmetric and stoichiometric 15 layers slabs with the vacuum of 20 Bohr. In addition, the real and imaginary parts of the dielectric function of the bulk and the BSb (110 slab were calculated and compared to each other. Our obtained results have a good agreement with the available results.

  5. Glancing angle deposition of SiO{sub 2} thin film microstructures: Investigations of optical and morphological properties

    Energy Technology Data Exchange (ETDEWEB)

    Tokas, R. B., E-mail:, E-mail:; Jena, S., E-mail:, E-mail:; Sarkar, P., E-mail:, E-mail:; Thakur, S., E-mail:, E-mail:; Sahoo, N. K., E-mail:, E-mail: [Atomic and Molecular Physics Division, Bhabha Atomic Research Centre, Mumbai-400085 (India)


    In present work, the optical and the morphological properties of micro-structured SiO{sub 2} thin films fabricated by using glancing angle deposition (GLAD) technique has been carried out. The results are compared with the normally deposited SiO{sub 2} films for the gained advantages. The influence of the glancing angle on the refractive index of porous SiO{sub 2} film was investigated by the spectral transmission measurement in 400–950 nm wavelength regimes. The refractive index has been found to be 1.14@532 nm for the porous SiO{sub 2} film deposited at a glancing angle of 85°. The density and surface qualities of these samples were primarily investigated by using grazing angle X-ray reflectivity (GIXR) and atomic force microscope (AFM) measurements. Results indicate a substantial decrease in film density and refractive index and increase in surface roughness and grain size for GLAD SiO{sub 2} compared to normally deposited SiO{sub 2} films.

  6. Performance Investigation of Multilayer MoS2 Thin-Film Transistors Fabricated via Mask-free Optically Induced Electrodeposition. (United States)

    Li, Meng; Liu, Na; Li, Pan; Shi, Jialin; Li, Guangyong; Xi, Ning; Wang, Yuechao; Liu, Lianqing


    Transition metal dichalcogenides, particularly MoS2, have recently received enormous interest in explorations of the physics and technology of nanodevice applications because of their excellent optical and electronic properties. Although monolayer MoS2 has been extensively investigated for various possible applications, its difficulty of fabrication renders it less appealing than multilayer MoS2. Moreover, multilayer MoS2, with its inherent high electronic/photonic state densities, has higher output driving capabilities and can better satisfy the ever-increasing demand for versatile devices. Here, we present multilayer MoS2 back-gate thin-film transistors (TFTs) that can achieve a relatively low subthreshold swing of 0.75 V/decade and a high mobility of 41 cm(2)·V(-1)·s(-1), which exceeds the typical mobility value of state-of-the-art amorphous silicon-based TFTs by a factor of 80. Ag and Au electrode-based MoS2 TFTs were fabricated by a convenient and rapid process. Then we performed a detailed analysis of the impacts of metal contacts and MoS2 film thickness on electronic performance. Our findings show that smoother metal contacts exhibit better electronic characteristics and that MoS2 film thickness should be controlled within a reasonable range of 30-40 nm to obtain the best mobility values, thereby providing valuable insights regarding performance enhancement for MoS2 TFTs. Additionally, to overcome the limitations of the conventional fabrication method, we employed a novel approach known as optically induced electrodeposition (OIE), which allows the flexible and precise patterning of metal films and enables rapid and mask-free device fabrication, for TFT fabrication.

  7. Electronic structure and optical properties of CdS{sub x}Se{sub 1−x} solid solution nanostructures from X-ray absorption near edge structure, X-ray excited optical luminescence, and density functional theory investigations

    Energy Technology Data Exchange (ETDEWEB)

    Murphy, M. W. [DESY (Deutsches Elektronen-Synchrotron), FS-PEX, Notkestrasse 85, 22607 Hamburg (Germany); Yiu, Y. M., E-mail:; Sham, T. K. [Department of Chemistry, University of Western Ontario, London, ON N6A5B7 (Canada); Ward, M. J. [Cornell High Energy Synchrotron Source (CHESS), Cornell University, Ithaca, NY 14853 (United States); Liu, L. [Institute of Functional Nano and Soft Materials (FUNSOM) and Soochow University-Western University Center for Synchrotron Radiation Research, Soochow University, Suzhou, Jiangsu, 215123 (China); Hu, Y. [Canadian Light Source, University of Saskatchewan, Saskatoon, SK S7N2V3 (Canada); Zapien, J. A. [Center Of Super-Diamond and Advanced Films (COSDAF) and Department of Physics and Materials Science, City University of Hong Kong, Hong Kong SAR (China); Liu, Yingkai [Institute of Physics and Electronic Information, Yunnan Normal University, Kunming, Yunnan, 650500 (China)


    The electronic structure and optical properties of a series of iso-electronic and iso-structural CdS{sub x}Se{sub 1−x} solid solution nanostructures have been investigated using X-ray absorption near edge structure, extended X-ray absorption fine structure, and X-ray excited optical luminescence at various absorption edges of Cd, S, and Se. It is found that the system exhibits compositions, with variable local structure in-between that of CdS and CdSe accompanied by tunable optical band gap between that of CdS and CdSe. Theoretical calculation using density functional theory has been carried out to elucidate the observations. It is also found that luminescence induced by X-ray excitation shows new optical channels not observed previously with laser excitation. The implications of these observations are discussed.

  8. Investigation of the potential of optical coherence tomography (OCT) as a non-invasive diagnostic tool in reproductive medicine (United States)

    Trottmann, Matthias; Homann, Christian; Leeb, R.; Doering, D.; Kuznetsova, J.; Reese, S.; Stief, C. G.; Koelle, S.; Sroka, R.


    Introduction and objective: In Europe, nearly every sixth couple in the reproductive age is involuntarily childless. In about 30%, both male and female reveal fertility problems. In about 10% of infertile men, azoospermia is the underlying cause. As conventional therapeutic options are limited, surgical testicular sperm extraction (TESE) is necessary to obtain sperms for assisted reproductive techniques. Regarding the females, up to 30% of all idiopathic infertilities are due to alterations of the uterine tube So far, no imaging technique, which does not require any labelling, is available to evaluate the male and female genital tract at a microscopic level under in vivo conditions. Thus, the aim of this study was to investigate the potential of optical coherence tomography (OCT) as a non-invasive diagnostic tool in gynaecology and andrology. Material and Methods: Tissues samples from the bovine testis, epididymis, vas deferens, ovary, oviduct (ampulla and isthmus) and uterus were obtained immediately after slaughter (14 cows aged 3 to 8 years and 14 bulls aged 3 to 6 years; breeds: Holstein- Friesian, and Deutsches Fleckvieh). Imaging was done by using the US Food and Drug Administration (FDA) approved probe-based Niris Imaging System (Imalux, Cleveland, Ohio, USA) and the Telesto 1325 nm OCT System and Ganymede 930 nm OCT System (Thorlabs Inc., Dachau, Germany). All images obtained were compared to histological images after paraffin embedding and HE staining. Results: OCT imaging visualized the microarchitecture of the testis, epididymis, spermatic duct and the ovary, oviduct and uterus. Using the Thorlabs systems a axial resolution of approx. 5μm and lateral resolution of 8- 15μm could be achieved. Different optical tissue volumes could be visualized, which depends on the optical penetration depth of the wavelength of the system used. While the tissue volume observed by probe based Imalux-OCT is similar to the used Thorlabs systems, the optical resolution is

  9. Preliminary investigations on the determination of three-dimensional dose distributions using scintillator blocks and optical tomography

    Energy Technology Data Exchange (ETDEWEB)

    Kroll, Florian; Karsch, Leonhard [OncoRay - National Center for Radiation Research in Oncology, Medical Faculty Carl Gustav Carus, TU Dresden, 01307 Dresden (Germany); Pawelke, Jörg [OncoRay - National Center for Radiation Research in Oncology, Medical Faculty Carl Gustav Carus, TU Dresden, 01307 Dresden, Germany and Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiation Physics, P.O. Box 510119, 01314 Dresden (Germany)


    dose profiles are in agreement with reference measurements. An inherent drawback of the scintillator is the nonlinear light output for high stopping-power radiation due to the quenching effect. It impacts the depth dose curves measured with the dosimeter. For single Bragg peak distributions this leads to a peak to plateau ratio of 2.8 instead of 4.5 for the reference ionization chamber measurement. Furthermore, the transmission of the clinical bremsstrahlung beams through the scintillator leads to the saturation of one camera, making dose reconstructions in that case presently not feasible.Conclusions: It is shown that distributions of scintillation light generated by proton or electron beams can be reconstructed by the dosimetry system within minutes. The quenching apparent for proton irradiation, and the yet not precisely determined position dependency of the imaging scale, require further investigation and corrections. Upgrading the prototype with larger or inorganic scintillators would increase the detectable proton and electron energy range. The presented results show that the determination of 3D dose distributions using scintillator blocks and optical tomography is a promising dosimetry method.

  10. Investigation of fluorine-doped tin oxide based optically transparent E-shaped patch antenna for terahertz communications

    Energy Technology Data Exchange (ETDEWEB)

    Anand, S., E-mail:, E-mail:, E-mail:; Darak, Mayur Sudesh, E-mail:, E-mail:, E-mail:; Kumar, D. Sriram, E-mail:, E-mail:, E-mail: [Department of Electronics and Communication Engineering, National Institute of Technology, Tiruchirappalli 620015 (India)


    In this paper, a fluorine-doped tin oxide based optically transparent E-shaped patch antenna is designed and its radiation performance is analyzed in the 705 – 804 GHz band. As optically transparent antennas can be mounted on optical display, they facilitate the reduction of overall system size. The proposed antenna design is simulated using electromagnetic solver - Ansys HFSS and its characteristics such as impedance bandwidth, directivity, radiation efficiency and gain are observed. Results show that the fluorine-doped tin oxide based optically transparent patch antenna overcomes the conventional patch antenna limitations and thus the same can be used for solar cell antenna used in satellite systems.

  11. Linear and quadratic magneto-optical Kerr effect investigation of Co2Mn1.30Si0.84 epitaxially grown on MgO (United States)

    Liu, Jihong; Qiao, Shuang; Wang, Shufang; Fu, Guangsheng


    We investigated the magneto-optical properties of a L21 ordered nonstoichiometric Co2Mn1.30Si0.84 film epitaxially grown on a MgO-buffered MgO (001) single-crystal substrate. Longitudinal magneto-optical Kerr effects (LMOKE) and rotating magneto-optical Kerr effect (ROT-MOKE) measurements suggest that the film exhibits a cubic magnetic anisotropy with the extracted cubic anisotropy constant of KC = 6.7 ×104 erg / cm3 . Orientation-dependent ROT-MOKE suggest that the quadratic magneto-optical Kerr effects (QMOKE) components also show fourfold symmetry with a modest amplitude of 3 mdeg, which is in accordance with complex Kerr angle expression for cubic symmetry systems. Our results suggest that ROT-MOKE is not only an efficient method to determine magnetic anisotropy parameters but also a good method to extract QMOKE components.

  12. Optical investigations and control of spindynamics in Mn doped II-VI quantum dots; Optische Untersuchung und Kontrolle der Spindynamik in Mn dotierten II-VI Quantenpunkten

    Energy Technology Data Exchange (ETDEWEB)

    Schmidt, Thomas


    The present thesis deals with the spin of charge carriers confined in CdSe/ZnSe quantum dots (QDs) closely linked to the polarization of emitted photons. II-VI material systems can be adequately mixed with the B-group element manganese. Such semimagnetic nanostructures offer a number of characteristic optical and electronic features. This is caused by an exchange interaction between the spin of optically excited carriers and the 3d electrons of the Mn ions. Within the framework of this thesis addressing of well defined spin states was realized by optical excitation of charge carriers. The occupation of different spin states was detected by the degree of polarization of the emitted photoluminescence (PL) light. For that purpose different optical methods of time-resolved and time-integrated spectroscopy as well as investigations in magnetic fields were applied. (orig.)

  13. Optical investigation of InAs quantum dots inserted in AlGaAs/GaAs modulation doped heterostructure (United States)

    Khmissi, H.; Baira, M.; Sfaxi, L.; Bouzaïene, L.; Saidi, F.; Bru-Chevallier, C.; Maaref, H.


    Optical properties of InAs quantum dots (QDs) inserted in AlGaAs/GaAs modulation doped heterostructure are investigated. To study the effect of carrier transfer behavior on the luminescence of self-assembled quantum dots, a series of sample has been prepared using molecular beam epitaxy (Riber 32 system) in which we have varied the thickness separating the delta dopage and the InAs quantum dots layer. Photoluminescence spectra show the existence of two peaks that can be attributed to transition energies from the ground state (E1-HH1) and the first excited state (E2-HH2). Two antagonist effects have been observed, a blue shift of the emission energies result from electron transferred from the AlGaAs/GaAs heterojunction to the InAs quantum dots and a red shift caused by the quantum confined Stark effect due to the internal electric field existing In the AlGaAs/GaAs heterojunction.

  14. Metallic behavior of NiS thin film under the structural, optical, electrical and ab initio investigation frameworks

    Energy Technology Data Exchange (ETDEWEB)

    Boughalmi, R. [Unité de physique des dispositifs à semi-conducteurs, Faculté des sciences de Tunis, Tunis El Manar University, 2092 Tunis (Tunisia); Rahmani, R. [Laboratoire de Physique des Couches Minces et Matériaux pour l' Electronique (LPC2ME). Département de physique, Faculté des Sciences, Université d' Oran Es-Sénia, Oran (Algeria); Département de physique, Université des Sciences et de la Technologie d' Oran- Mohamed-Boudiaf, Oran (Algeria); Boukhachem, A., E-mail: [Unité de physique des dispositifs à semi-conducteurs, Faculté des sciences de Tunis, Tunis El Manar University, 2092 Tunis (Tunisia); Amrani, B.; Driss-Khodja, K. [Laboratoire de Physique des Couches Minces et Matériaux pour l' Electronique (LPC2ME). Département de physique, Faculté des Sciences, Université d' Oran Es-Sénia, Oran (Algeria); Amlouk, M. [Unité de physique des dispositifs à semi-conducteurs, Faculté des sciences de Tunis, Tunis El Manar University, 2092 Tunis (Tunisia)


    Nickel sulfide (NiS) thin films were deposited on the glass substrates by spray pyrolysis at 250 °C using an aqueous solution which contains nickel chloride hexahydrate and thiourea as precursors. X-ray diffraction analysis confirms that the hexagonal structure is being part of P6{sub 3}/mmc space group of the deposited films with (100) preferred orientation and lattice parameters a = 3.441 Å and c = 5.320 Å. The optical properties, investigated through transmittance and reflectance measurements reveal that the direct band gap energy (Eg) is around 0.55 eV. The electrical study shows a metallic behavior of the current II-VI binary compound. This behavior regarding NiS II-VI binary sulfide was confirmed by numerical studies based on the density functional theory (DFT) were adopted. The ground state quantities, such as lattice parameter, bulk modulus and its pressure derivative as well as the elastic constants were obtained. The values are consistent with the stability of hexagonal structure. The band structure and the states densities of such material were studied. The results show that there is an agreement between experimental and simulation. - Highlights: • NiS thin films are synthesized by Spray pyrolysis. • NiS is a low band gap compound. • These films have interesting electrical properties showing a metallic behavior. • Computational study confirms the electrical measurements.

  15. Investigation of optical inhomogeneity of MgO:PPLN crystals for frequency doubling of 1560 nm laser (United States)

    Guo, Shanlong; Ge, Yulong; Han, Yashuai; He, Jun; Wang, Junmin


    The asymmetrical phase-matching temperature tuning curves of periodically-poled 5%-mol MgO-doped lithium niobate (MgO:PPLN) bulk crystals for frequency doubling of 1560 nm telecom laser have been observed experimentally and analyzed theoretically. We find that the asymmetrical phenomena are resulted from the variation in the extraordinary refractive index by the doping concentration inhomogeneity of the crystals. The critical parameters of phase-matching temperature mismatching γ(γ=δTpm/ΔT, in which δTpm is the change of the phase-matching temperature due to the doping concentration inhomogeneity, and ΔT is the temperature acceptance bandwidth) and the thermal refractive index ∂(Δn)/∂T are investigated. Our analysis method is not only a reasonable explanation to the experiment, but also can be a simple evaluation way of optical quality of the given MgO:PPLN bulk crystals. Moreover, the MgO:PPLN bulk crystal is used in single-pass configuration for frequency doubling a 4.4 W Erbium-doped fiber amplifier boosted 1560 nm telecom laser, and 300 mW of tunable 780 nm laser is obtained, corresponding to a conversion efficiency of 6.9%. This source provides a simple and compact laser system for rubidium atom cooling and manipulation experiments.

  16. Towards nano-optical tweezers with graphene plasmons: Numerical investigation of trapping 10-nm particles with mid-infrared light (United States)

    Zhang, Jianfa; Liu, Wenbin; Zhu, Zhihong; Yuan, Xiaodong; Qin, Shiqiao


    Graphene plasmons are rapidly emerging as a versatile platform for manipulating light at the deep subwavelength scale. Here we show numerically that strong optical near-field forces can be generated under the illumination of mid-IR light when dielectric nanoparticles are located in the vicinity of a nanostructured graphene film. These near-field forces are attributed to the excitation of the graphene’s plasmonic mode. The optical forces can generate an efficient optical trapping potential for a 10-nm-diameter dielectric particle when the light intensity is only about about 4.4 mW/μm2 and provide possibilities for a new type of plasmonic nano-tweezers. Graphene plasmonic tweezers can be potentially exploited for optical manipulation of nanometric biomolecules and particles. Moreover, the optical trapping/tweezing can be combined with biosensing and provide a versatile platform for studing biology and chemistry with mid-IR light.

  17. Electrical and optical investigations in Te–Ge–Ag and Te–Ge–AgI chalcogenide glasses

    Energy Technology Data Exchange (ETDEWEB)

    Cui, S. [Glass and Ceramic Laboratory, Institute of Chemical Sciences of Rennes, UMR-CNRS 6226, University of Rennes 1, 35042 Rennes cedex (France); Department of Materials Science and Engineering, Zhejiang University, 38 Zheda Road, Hangzhou 310027 (China); Le Coq, D., E-mail: [Glass and Ceramic Laboratory, Institute of Chemical Sciences of Rennes, UMR-CNRS 6226, University of Rennes 1, 35042 Rennes cedex (France); Boussard-Plédel, C.; Bureau, B. [Glass and Ceramic Laboratory, Institute of Chemical Sciences of Rennes, UMR-CNRS 6226, University of Rennes 1, 35042 Rennes cedex (France)


    Highlights: • Evolution of the electrical conductivities in Ag and AgI-GeTe{sub 4} glasses. • We demonstrate a change of a conductivity type (electronic vs ionic) in AgI–GeTe{sub 4} glasses. • A structural model for Ag and AgI–GeTe{sub 4} glasses is proposed. • The role of Ag in the structure of the Ag and AgI–GeTe{sub 4} glasses is described. - Abstract: (GeTe{sub 4}){sub 100−x}Ag{sub x} and (GeTe{sub 4}){sub 100−x}(AgI){sub x} glasses were prepared by a melting-quenching method. The glass electrical conductivity was investigated by both electrochemical impedance spectroscopy at different temperatures from 283 K to 333 K and four-probe method at room temperature (293 K). Meanwhile, as a major factor determining the electrical conductivity of a solid, optical band gap was also studied. By comparing the electrical conductivity values and glass optical band gap evolution, it was found that (GeTe{sub 4}){sub 100−x}Ag{sub x} glasses are mainly electronic conductive. On the other hand, the electrical conductivities of (GeTe{sub 4}){sub 100−x}(AgI){sub x} glasses firstly show a monotonic decrease by increasing AgI up to 15 mol.%, and then an increase when the AgI content is higher than 15 mol.%. The activation energy E{sub a} and the pre-exponential factor σ{sub 0} show apparent turning point when AgI content is 15 mol.%, signifying a conductivity mechanism change. In this paper, correlations between the conductivity and hypothetical structures in (GeTe{sub 4}){sub 100−x}Ag{sub x} and (GeTe{sub 4}){sub 100−x}(AgI){sub x} glasses are done and the importance of the Ag role is underlined.

  18. Five-membered rings as diazo components in optical data storage devices: An ab initio investigation of the lowest singlet excitation energies

    DEFF Research Database (Denmark)

    Åstrand, P.-O.; Sommer-Larsen, P.; Hvilsted, Søren;


    been investigated as diazo components for a potential use in optical das storage materials. It is found that the diazo compounds with two heterocyclic five-membered rings have pi --> pi* excitation energies corresponding to laser wavelengths in the region 450-500 nm whereas one five-membered ring...

  19. Decrease of the Link PMD by Fiber Exchange and Investigation of the PMD Distribution along Buried Optical Fibers with a POTDR

    Directory of Open Access Journals (Sweden)

    Armin Ehrhardt


    Full Text Available The accumulated PMD along several fibers in an optical network was measured in order to identify those short fiber portions exhibiting high PMD. By replacing high-PMD-portion(s in each fiber, the overall-PMD could be reduced significantly. Additionally the PMDaccumulation of different fibers in the same buried cable was investigated and compared to each other.

  20. Atomic force and optical near-field microscopic investigations of polarization holographic gratings in a liquid crystalline azobenzene side-chain polyester

    DEFF Research Database (Denmark)

    Ramanujam, P.S.; Holme, N.C.R.; Hvilsted, S.


    Atomic force and scanning near-field optical microscopic investigations have been carried out on a polarization holographic grating recorded in an azobenzene side-chain Liquid crystalline polyester. It has been found that immediately following laser irradiation, a topographic surface grating...

  1. Investigation of chromophore-chromophore interaction by electro-optic measurements, linear dichroism, x-ray scattering, and density-functional calculations

    DEFF Research Database (Denmark)

    Apitz, Dirk; Bertram, R.P.; Benter, N.;


    Free-beam interferometry and angle-resolved absorption spectra are used to investigate the linear electro-optic coefficients and the linear dichroism in photoaddressable bis-azo copolymer thin films. From the first- and second order parameters deduced, the chromophore orientation distribution is ...

  2. Investigation on the bit error rate performance of 40Gb/s space optical communication system based on BPSK scheme (United States)

    Li, Mi; Li, Bowen; Zhang, Xuping; Song, Yuejiang; Liu, Jia; Tu, Guojie


    Space optical communication technique is attracting increasingly more attention because it owns advantages such as high security and great communication quality compared with microwave communication. As the space optical communication develops, people have already achieved the communication at data rate of Gb/s currently. The next generation for space optical system have goal of the higher data rate of 40Gb/s. However, the traditional optical communication system cannot satisfy it when the data rate of system is at such high extent. This paper will introduce ground optical communication system of 40Gb/s data rate as to achieve the space optical communication at high data rate. Speaking of the data rate of 40Gb/s, we must apply waveguide modulator to modulate the optical signal and magnify this signal by laser amplifier. Moreover, the more sensitive avalanche photodiode (APD) will be as the detector to increase the communication quality. Based on communication system above, we analyze character of communication quality in downlink of space optical communication system when data rate is at the level of 40Gb/s. The bit error rate (BER) performance, an important factor to justify communication quality, versus some parameter ratios is discussed. From results, there exists optimum ratio of gain factor and divergence angle, which shows the best BER performance. We can also increase ratio of receiving diameter and divergence angle for better communication quality. These results can be helpful to comprehend the character of optical communication system at high data rate and contribute to the system design.

  3. Regulation of paracellular Na+ and Cl(-) conductances by hydrostatic pressure. (United States)

    Tokuda, Shinsaku; Niisato, Naomi; Nagai, Toshiki; Taruno, Akiyuki; Nakajima, Ken-Ichi; Miyazaki, Hiroaki; Yamada, Toshiki; Hosogi, Shigekuni; Ohta, Mariko; Nishio, Kyosuke; Iwasaki, Yoshinobu; Marunaka, Yoshinori


    The effect of hydrostatic pressure on the paracellular ion conductance (Gp) composed of the Na(+) conductance (G(Na)) and the Cl(-) conductance (G(Cl)) has been Investigated. Gp, G(Na) and G(Cl) were time-dependently increased after applying an osmotic gradient generated by NaCl with basolateral hypotonicity. Hydrostatic pressure (1-4cm H2O) applied from the basolateral side enhanced the osmotic gradient-induced increase in Gp, G(Na) and G(Cl) in a magnitude-dependent manner, while the hydrostatic pressure applied from the apical side diminished the osmotic gradient-induced increase in Gp, G(Na) and G(Cl). How the hydrostatic pressure influences Gp, G(Na) and G(Cl) under an isosmotic condition was also investigated. Gp, G(Na) and G(Cl) were stably constant under a condition with basolateral application of sucrose canceling the NaCl-generated osmotic gradient (an isotonic condition). Even under this stable condition, the basolaterally applied hydrostatic pressure drastically elevated Gp, G(Na) and G(Cl), while apically applied hydrostatic pressure had little effect on Gp, G(Na) or G(Cl). Taken together, these observations suggest that certain factors controlled by the basolateral osmolality and the basolaterally applied hydrostatic pressure mainly regulate the Gp, G(Na) and G(Cl).

  4. Investigation of optical and electrical properties of L-Cystein doped zinc thiourea chloride (ZTC) crystal for nonlinear optical (NLO) applications (United States)

    Anis, Mohd; Shaikh, R. N.; Shirsat, M. D.; Hussaini, S. S.


    The single crystal of L-Cystein doped zinc thiourea chloride (ZTC) has been grown by slow evaporation technique. The optical study revealed that the doped ZTC crystal has high transmission with lowest cut off wavelength of 306 nm. The optical band gap was found to be 4.2 eV. The transition band gaps were studied using the photoluminescence spectrum. The incorporation of L-Cystein in ZTC was estimated qualitatively by FT-IR analysis. The presence of dopant was confirmed by energy diffraction X-ray analysis (EDAX) analysis. The lower dielectric characteristics of doped ZTC crystal were scrutinized by dielectric measurements. The high thermal stability of grown crystal was ascertained by TG/DTA analysis. The Second harmonic generation (SHG) efficiency measured using Nd-YAG laser is 1.96 times that of pure ZTC.

  5. MPACVD processing technologies for planar integrated optics (United States)

    Li, Cheng-Chung; Boudreau, Robert A.; Bowen, Terry P.


    Optical circuits based on low-loss glass waveguide are the practical and promising approaches to integrate different functional components for optical communication system. Microwave plasma assisted chemical vapor deposition produces superior quality, low birefringence, low-loss, planar waveguides for integrated optical devices. A microwave plasma initiates the chemical vapor of SiCl4, GeCl4 and oxygen. A Ge-doped silica layer thus deposited on the substrates with reasonable high growth rate. Film properties are based on various parameters, such as chemical flow rates, chamber pressure and temperature, power level and injector design. The main emphasis has been on optimizing the deposition parameters and reproducibility. An uniform, low-loss film can be made by properly balancing the precursor flows. The refractive index of deposited film can also be controlled by adjusting the flow ratio of SiCl4 and GeCl4 bubblers. Deposited films was characterized by prism coupler, loss measurement, residual stress, and composition analysis. The resulted refractive index step can be varied between 1.46 to 1.60. Waveguide can be fabricated with any desired refractive index profile. Standard photolithography defines the waveguide pattern on mask layer. Core layer was remove by the plasma dry etch which has been investigated by both reactive ion etch (RIE) and inductively coupled plasma etch. Etch rate of 3000-4000 angstrom/min has been achieved by using ICP compared to typical etch rate of 200-300 angstrom/min by using conventional RIE.

  6. Influence of multiple reflection and optical interference on the magneto-optical properties of Co-Pt alloy films investigated by using the characteristic matrix method

    CERN Document Server

    Zou, Z Q; Kim, K W


    The magneto-optical Kerr effect (MOKE) of a multilayered system was described by using the characteristic matrix method based on the electromagnetic wave theory. In addition to the multiple reflection and the optical interference, a contribution from the plasma resonance absorption of a metallic layer can be included in the formulation. As an example, we carried out a simulation of the MOKE for Co sub 0 sub . sub 2 sub 5 Pt sub 0 sub . sub 7 sub 5 alloy films with and without a Pt buffer layer. It was found that the Kerr rotation and the read-out figure of merit of a film directly deposited on a glass substrate were enhanced at a thickness below 40 nm owing to the multiple reflection and the optical interference. This enhancement was more remakable at long wavelengths when light was incident on the substrate side. However, the introduction of a Pt buffer layer was not beneficial in improving the Kerr rotation and the figure of merit, although it promoted the perpendicular magnetic anisotropy of the film, as r...

  7. Investigation of the collision line broadening problem as applicable to the NASA Optical Plume Anomaly Detection (OPAD) system, phase 1 (United States)

    Dean, Timothy C.; Ventrice, Carl A.


    As a final report for phase 1 of the project, the researchers are submitting to the Tennessee Tech Office of Research the following two papers (reprinted in this report): 'Collision Line Broadening Effects on Spectrometric Data from the Optical Plume Anomaly System (OPAD),' presented at the 30th AIAA/ASME/SAE/ASEE Joint Propulsion Conference, 27-29 June 1994, and 'Calculation of Collision Cross Sections for Atomic Line Broadening in the Plume of the Space Shuttle Main Engine (SSME),' presented at the IEEE Southeastcon '95, 26-29 March 1995. These papers fully state the problem and the progress made up to the end of NASA Fiscal Year 1994. The NASA OPAD system was devised to predict concentrations of anomalous species in the plume of the Space Shuttle Main Engine (SSME) through analysis of spectrometric data. The self absorption of the radiation of these plume anomalies is highly dependent on the line shape of the atomic transition of interest. The Collision Line Broadening paper discusses the methods used to predict line shapes of atomic transitions in the environment of a rocket plume. The Voigt profile is used as the line shape factor since both Doppler and collisional line broadening are significant. Methods used to determine the collisional cross sections are discussed and the results are given and compared with experimental data. These collisional cross sections are then incorporated into the current self absorbing radiative model and the predicted spectrum is compared to actual spectral data collected from the Stennis Space Center Diagnostic Test Facility rocket engine. The second paper included in this report investigates an analytical method for determining the cross sections for collision line broadening by molecular perturbers, using effective central force interaction potentials. These cross sections are determined for several atomic species with H2, one of the principal constituents of the SSME plume environment, and compared with experimental data.

  8. Experimental Investigation of Transmission Properties and All-Optical Label Swapping of Orthogonal IM/FSK Labeled Signals

    Institute of Scientific and Technical Information of China (English)

    Pablo; V.; Holm-Nielsen; Christophe; Peucheret; Idelfonso; Tafur; Monroy; Palle; Jeppesen


    OpticallylabeledIM/FSKsignalsaretransmittedover50kmofSMFunderdifferentcompensationschemes.All-optical label swapping based on MZ-SOA and EAM is presented. Transmission followed by label swapping shows a 2dB overall power penalty.


    Institute of Scientific and Technical Information of China (English)

    CHEN Min; JIANG Deli; ZHANG Chunyan; YU Long; YAN Yongsheng


    Acylation reaction of anthracene with oxalyl chloride in the presence of [Emim]Cl-AlCl3 ionic liquid has been investigated. Pure 1,2-aceanthryenedione, which is used as intermediate of functional aromatic polymer material, was obtained by recrystalling the reaction mixture with aether and was determined by GC/MS, 1HNMR and FTIR analysis. The influences of various parameters,such as the contents of AlCl3 in [Emim]Cl-AlCl3, the amount of acylation agent, amount of [Emim]Cl-AlCl3, reaction temperature and reaction time were investigated. The optimum conditions were as follows: the molar fraction of AlCl3 in ionic liquid [x(AlCl3)] being 0.67, molar ratio of ionic liquid to anthracene being 2:1, molar ratio of oxalyl chloride to anthracene being 2:1,reaction temperature being 40 ℃ and reaction time being 6h. Under above conditions, the yield and selectivity of 1,2-aceanthrylenedione can reach 91.5% and 98.3% respectively. Further more,[Emim]Cl-AlCl3 ionic liquid, compared with metal halides such as AlCl3, was found to catalyze the reaction as a novel environmental friendly catalyst and solvent and can be reused.

  10. Preparing different phases of Mg-Li-Sm alloys by molten salt electrolysis in LiCl-KCl-MgCl_2-SmCl_3 melts

    Institute of Scientific and Technical Information of China (English)

    韩伟; 田阳; 张密林; 叶克; 赵全友; 魏树权


    Different phases of Mg-Li-Sm alloys were prepared by galvanostatic electrolysis in LiCl-KCl-MgCl2-SmCl3 melts at 670 °C.The electrolysis process and phase control of Mg-Li-Sm alloys were studied.The microstructures of α,α+β,β phases of Mg-Li-Sm alloys were characterized by X-ray diffraction(XRD) and optical microscope(OM).Analysis of scanning electron microscopy(SEM) and EDS mapping analysis showed that Mg distributed homogeneously in Mg-Li-Sm alloys.EDS result showed that the distribution of Sm was more at...

  11. Inductively coupled plasma etching of GaN using SiCl{sub 4}/Cl{sub 2}/Ar for submicron-sized features fabrication

    Energy Technology Data Exchange (ETDEWEB)

    Dylewicz, R.; Patela, S. [Photonics Group, Faculty of Microsystem Electronics and Photonics, Wroclaw University of Technology, ul. Janiszewskiego 11/17, 50-372 Wroclaw (Poland); Hogg, R.A.; Fry, P.W.; Parbrook, P.J.; Airey, R.; Tahraoui, A. [Department of Electronic and Electrical Engineering, EPSRC National Center for III-V Technologies, University of Sheffield, Sir Frederick Mappin Building, Mappin Street, Sheffield S1 3JD (United Kingdom)


    In this paper we report the optimization of the fabrication process of a grating coupler, which is fully integrated with a GaN planar waveguide. To our knowledge, this is the first report of a grating-assisted optical coupler in gallium nitride. ICP dry etching of n-doped GaN layers was investigated, where SiCl{sub 4}/Cl{sub 2}/Ar gas mixture was used under different etching conditions. We report n-GaN ICP etching ratio of 520-2680 Aa min{sup -1} as well as etching selectivity of GaN over SiO{sub 2} from 3 to 8, in the most cases. Grating ridge and grating groove width as well as the sidewalls slope were evaluated by SEM microscope. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  12. Investigations on nucleation, HRXRD, optical, piezoelectric, polarizability and Z-scan analysis of L-arginine maleate dihydrate single crystals (United States)

    Sakthy Priya, S.; Alexandar, A.; Surendran, P.; Lakshmanan, A.; Rameshkumar, P.; Sagayaraj, P.


    An efficient organic nonlinear optical single crystal of L-arginine maleate dihydrate (LAMD) has been grown by slow evaporation solution technique (SEST) and slow cooling technique (SCT). The crystalline perfection of the crystal was examined using high-resolution X-ray diffractometry (HRXRD) analysis. Photoluminescence study confirmed the optical properties and defects level in the crystal lattice. Electromechanical behaviour was observed using piezoelectric co-efficient (d33) analysis. The photoconductivity analysis confirmed the negative photoconducting nature of the material. The dielectric constant and loss were measured as a function of frequency with varying temperature and vice-versa. The laser damage threshold (LDT) measurement was carried out using Nd:YAG Laser with a wavelength of 1064 nm (Focal length is 35 cm) and the obtained results showed that LDT value of the crystal is high compared to KDP crystal. The high laser damage threshold of the grown crystal makes it a potential candidate for second and higher order nonlinear optical device application. The third order nonlinear optical parameters of LAMD crystal is determined by open-aperture and closed-aperture studies using Z-scan technique. The third order linear and nonlinear optical parameters such as the nonlinear refractive index (n2), two photon absorption coefficient (β), Real part (Reχ3) and imaginary part (Imχ3) of third-order nonlinear optical susceptibility are calculated.

  13. Investigation of annealing-treatment on structural and optical properties of sol–gel-derived zinc oxide thin films

    Indian Academy of Sciences (India)

    Shenghong Yang; Ying Liu; Yueli Zhang; Dang Mo


    The transparent ZnO thin films were prepared on Si(100) substrates by the sol–gel method. The structural and optical properties of ZnO thin films, submitted to an annealing treatment in the 400–700°C ranges are studied by X-ray diffraction (XRD) and UV-visible spectroscopic ellipsometry (SE). XRD measurements show that all the films are crystallized in the hexagonal wurtzite phase and present a random orientation. Three prominent peaks, corresponding to the (100) phase (2 ≈ 31.8°), (002) phase (2 ≈ 34.5°), and (110) phase (2 ≈ 36.3°) appear on the diffractograms. The crystallite size increases with increasing annealing temperature. These modifications influence the optical properties. The optical constants and thickness of the films have been determined by analysing the SE spectra. The optical bandgap has been determined from the extinction coefficient. We found that the refractive index and the extinction coefficient increase with increasing annealing temperature. The optical bandgap energy decreases with increasing annealing temperature. These mean that the optical quality of ZnO films is improved by annealing.

  14. Electrochemical Codeposition of Al-Li-Mg Alloys at Solid Aluminum Electrode from LiCl-KCl-MgCl2 Molten Salt System (United States)

    Ye, Ke; Zhang, Mi Lin; Chen, Ye; Han, Wei; de Yan, Yong; Cao, Peng


    The electrochemical codeposition of Mg and Li at an aluminium electrode in LiCl-KCl (50:50 wt pct) melts containing different concentrations of MgCl2 at 893 K (620 °C) to form Al-Li-Mg alloys was investigated. Cyclic voltammograms showed that the potential of Li metal deposition at an Al electrode, before the addition of MgCl2, is more positive than that of Li metal deposition at an Mo electrode, which indicated the formation of an Al-Li alloy. The underpotential deposition of magnesium at an aluminium electrode leads to the formation of Al-Mg alloys, and the succeeding underpotential deposition of lithium on predeposited Al-Mg alloys leads to the formation of Al-Li-Mg alloys. Chronopotentiometric measurements indicated that the codeposition of Mg and Li occurs at current densities lower than -0.668 A cm-2 in LiCl-KCl-MgCl2 (8 wt pct) melts at an aluminium electrode. The chronoamperometric studies indicated that the onset potential for the codeposition of Mg and Li is -2.000 V, and the codeposition of Mg and Li at an aluminium electrode is formed into Al-Li-Mg alloys when the applied potentials are more negative than -2.000 V. X-ray diffraction and inductively coupled plasma analysis indicated that Al-Li-Mg alloys with different lithium and magnesium contents were prepared via potentiostatic and galvanostatic electrolysis. The microstructure of typical dual phases of the Al-Li-Mg alloy was characterized by an optical microscope and by scanning electron microscopy. The analysis of energy dispersive spectrometry showed that the elements of Al and Mg distribute homogeneously in the Al-Li-Mg alloy. The lithium and magnesium contents of Al-Li-Mg alloys can be controlled by MgCl2 concentrations and by electrolytic parameters.

  15. A Numerical Investigation of the Strain Effect on Saturation Optical Intensity in Electroabsorption Modulators Based on Asymmetric Intra-step-barrier Coupled Double Strained Quantum Wells (United States)

    Abedi, Kambiz


    In this paper, the strain effect on saturation optical intensity in electroabsorption modulators (EAMs) based on asymmetric intra-step-barrier coupled double strained quantum well (AICD-SQWs) active region is theoretically investigated and compared with intra-step quantum well (IQW) structure. For this purpose, the thermionic emission and tunneling escape processes are taken into account and the escape times of photogenerated carriers are calculated. Then, the electroabsorption coefficient is calculated for different well strains for TE input light polarization. Finally, the saturation optical intensity of electroabsorption modulators with AICD-SQW structures in comparison with IQW structure is evaluated. Numerical results show that the tensile strain of well has the most significant effect on the saturation optical intensity of electroabsorption modulators with AICD-SQW structures due to reduction in escape times.

  16. Theoretical investigation of the electronic structure, optical, elastic and thermodynamics properties of a newly binary boron nitride (T-B3N3) (United States)

    Zhao, Shibo; Long, Jianping


    The ultrasoft pseudopotential planewave (UPPW) within density functional theory (DFT) has been used to investigate the electronic structure, optical, elastic and thermodynamics properties of newly binary boron nitride (T-B3N3). The calculated lattice parameters are in good agreement with previous theoretical results and deviated are less than 0.4%. The electronic structure showed that the T-B3N3 is metallic, and the optical spectra exhibit a noticeable anisotropy. The static dielectric constants, optical permittivity constants and the elastic properties are calculated. From our results, we observe that T-B3N3 is mechanically unstable and ductile. The entropy, enthalpy, free energy, heat capacity and Debye temperature of T-B3N3 was obtained. Up to now, there are no available experimental data about those properties. The results obtained in the present paper could provide important reference data for future studies.

  17. Experimental investigation on nonlinear dynamics of 1550 nm VCSEL simultaneously subject to orthogonal optical injection and negative optoelectronic feedback (United States)

    Deng, Tao; Xia, Guang-Qiong; Chen, Jian-Jun; Tang, Xi; Lin, Xiao-Dong; Yang, Xin; Huang, Shou-Wen; Wu, Zheng-Mao


    Nonlinear dynamic characteristics of a 1550 nm vertical-cavity surface-emitting laser (1550 nm VCSEL) simultaneously subject to orthogonal optical injection and negative optoelectronic feedback are experimentally investigated. The results show that, under suitable orthogonal optical injection the VCSEL can exhibit rich nonlinear dynamic behaviors such as stable state (S), period-one (P1), period-two (P2), chaos (CO), stable injection locking (SIL) and polarization switching (PS). After further introducing negative optoelectronic feedback with a certain feedback delay time, the dynamic distribution of the orthogonal optical injection 1550 nm VCSEL is significantly affected, and some new phenomena including three-frequency quasiperiodic (Q3) state can be observed. With the increase of optoelectronic feedback strength, the S and SIL regions typically are shrank, while the quasiperiodic (QP) and CO regions are enlarged.

  18. The electronic structure and optical properties of XSi(X = Fe,Ru,Os): A first principles investigation within the modified Becke-Johnson exchange potential plus LDA

    Energy Technology Data Exchange (ETDEWEB)

    Li Jia, E-mail:; Zhang Zhidong; Ji Qing; Zhang Hui; Luo Hongzhi


    Highlights: Black-Right-Pointing-Pointer Reproduce of band gap for XSi(X = Fe,Ru,Os) with gap of {approx}10{sup -1} eV. Black-Right-Pointing-Pointer Using the mBJ + LDA first principles in comparison with GGA and LDA. Black-Right-Pointing-Pointer Theoretical optical conductivity is in agreement with the measurement. - Abstract: The electronic structure, optical reflectivity spectra and optical conductivity of semiconducting transition-metal silicides FeSi, RuSi and OsSi have been investigated by using first principles calculation within the recent developed modified Becke-Johnson exchange potential plus local-density approximation (mBJ + LDA). The electronic structures produced by mBJ + LDA, generalized gradient approximation (GGA) and LDA are rather similar although the band gap has been enlarged more or less by the mBJ + LDA compared to the GGA and LDA for the three compounds. The mBJ + LDA, GGA and LDA all have overestimated the band gap for FeSi and OsSi compared to the experiment. For RuSi, the theoretical gap values are basically close to the experimental values and the improvement of gap by mBJ + LDA is only 0.04 eV in comparison with the GGA. The mBJ + LDA and GGA also produce similar results with respect to their optical properties including the reflectivity spectra and optical conductivity except that for the reflectivity spectra of FeSi, the GGA result is little better consistent with the experimental measurement than the mBJ + LDA result. The optical conductivity calculated by mBJ + LDA and GGA both exhibits the absorption edge, in well correspondence to the optical measurement.

  19. Experimental Investigation of the Thermal Upset and Recovery of the National Ignition Facility's Optics Module

    Energy Technology Data Exchange (ETDEWEB)

    J. D. Bernardin


    The National Ignition Facility (NIF) at Lawrence Livermore National Laboratory is being constructed as the latest in a series of high-power laser facilities to study inertial confinement fusion. In particular, the NIF will generate and amplify 192 laser beams and focus them onto a fusion fuel capsule the size of a BB. The energy deposited by the laser beams will raise the core temperature of the target to 100,OOO,OOO C, which will ignite the fusion fuel and produce a fusion energy output that is several times greater than the energy input. The ability to generate, condition, and focus 192 laser beams onto a target the size of a BB, requires precision optical hardware and instrumentation. One of the most critical pieces of optical hardware within the NIF is the Optics Module (OM), a mechanical apparatus which is responsible for optical focusing and frequency conversion of the laser beam to optimize the energy deposition at the fusion target. The OM contains two potassium dihydrogen phosphate (KDP), frequency conversion crystals and a focusing lens. The functionality of the KDP crystals is extremely temperature sensitive. Small temperature changes on the order of 0.1 C can significantly alter the performance of these components. Consequently, to maximize NIF system availability and minimize beam conditioning problems, accurate temperature control of the OM optical components was deemed a necessity. In this study, an experimental OM prototype, containing mock frequency conversion crystals and a focusing lens, was used determine the thermal stability provided by a prototype water temperature control system. More importantly, the OM prototype was used to identify and characterize potential thermal upsets and corresponding recovery times of the KDP crystals. The results of this study indicate that the water temperature control system is adequate in maintaining uniform steady-state temperatures within the OM. Vacuum pump-down and venting of the OM generated significant

  20. Intermediate-range chemical ordering of cations in molten RbCl-AgCl

    Energy Technology Data Exchange (ETDEWEB)

    Tahara, S. [Department of Physics and Earth Sciences, Faculty of Science, University of the Ryukyus, Okinawa 903-0213 (Japan); Research and Utilization Division, Japan Synchrotron Radiation Research Institute (JASRI, SPring-8), Hyogo 679-5198 (Japan); Kawakita, Y. [J-PARC Center, Japan Atomic Energy Agency (JAEA), Ibaraki 319-1195 (Japan); Shimakura, H. [Faculty of Pharmacy, Niigata University of Pharmacy and Applied Life Sciences, Niigata 956-8603 (Japan); Ohara, K. [Research and Utilization Division, Japan Synchrotron Radiation Research Institute (JASRI, SPring-8), Hyogo 679-5198 (Japan); Fukami, T. [Department of Physics and Earth Sciences, Faculty of Science, University of the Ryukyus, Okinawa 903-0213 (Japan); Takeda, S. [Department of Physics, Faculty of Sciences, Kyushu University, Fukuoka 812-8581 (Japan)


    A first sharp diffraction peak (FSDP) is observed in the X-ray total structure factor of a molten mixture of RbCl-AgCl, while both pure melts of RbCl and AgCl do not exhibit FSDP individually. Molecular dynamics simulations were performed to investigate the origin of the FSDP with the polarizable ion model (PIM). Coexistence of covalent Ag–Cl and ionic Rb–Cl bonds leads the system to evolve intermediate range ordering, which is simulated by introducing the induced polarization in different ways between Ag–Cl with fully polarizable treatment based on Vashishta-Raman potential and Rb–Cl with suppression over-polarization in the nearest neighbor contribution based on Born-Meyer potential. The partial structure factors for both the Ag–Ag and Rb–Rb correlations, S{sub AgAg}(Q) and S{sub RbRb}(Q), show a positive contribution to the FSDP, while S{sub AgRb}(Q) for the Ag–Rb correlation exhibits a negative contribution, indicating that Ag and Rb ions are distributed in an alternating manner within the intermediate-range length scale. The origin of the intermediate-range chemical ordering of cations can be ascribed to the preferred direction of the dipole moments of anions in the PIM.

  1. Optical and morphological investigation of aluminium and nickel oxide composite films deposited by spray pyrolysis method as a basis of solar thermal absorber

    Indian Academy of Sciences (India)

    A Bagheri Khatibani; S M Rozati


    Applications of alumina and nickel oxide in various fields specially in solar energy conversion technology encouraged us to study physical properties of such materials. Hence after the deposition of the thin films on glass substrate by spray pyrolysis, using X-ray diffraction (XRD), scanning electron microscopy (SEM), and UV–visible spectrophotometry, various physical properties were investigated. Different optical quantities such as optical band gap, refractive index, extinction coefficient, dielectric constants, volume and surface energy loss functions and optical conductivity were determined. Within this paper for different nickel to aluminium ratio (from 20/80 to 80/20 ratio) at specific substrate temperatures (300°C), decrease of optical transmittance with nickel content was notable. Using the transmittance data, other optical quantities were achieved by a numerical approximation method. We also observed an increase in the volume energy loss (VELF) more than the surface energy loss (SELF) and simultaneously a decrease trend prevailed according to nickel amount. On the basic of the XRD results, the amorphous phase changed by the presence of more nickel and according to SEM, more obvious nanosized spherical grains at higher nickel ratios can be observed.

  2. Femtosecond laser written optical waveguides in z-cut MgO:LiNbO3 crystal: Fabrication and optical damage investigation (United States)

    Lv, Jinman; Cheng, Yazhou; Lu, Qingming; Vázquez de Aldana, Javier R.; Hao, Xiaotao; Chen, Feng


    We report on the fabrication of the dual-line waveguides and cladding waveguide in z-cut MgO:LiNbO3 crystal by femtosecond laser inscription. Due to the diverse modification of refractive index along TE/TM polarization induced by femtosecond laser pulses, the two geometries exhibit different guiding performances: the dual-line waveguides only support extraordinary index polarization, whilst the depressed cladding waveguide supports guidance along both extraordinary and ordinary index polarizations. The measured optical damage of these waveguides at the wavelength of 532 nm is higher than that of the previously reported ion-implanted waveguides in Zr-doped LiNbO3. The propagation loss of depressed cladding waveguide is measured as low as 0.94 dB/cm at 632.8 nm wavelength. It is found that the optical damage threshold (∼105 W/cm2) of the dual-line waveguide is one order of magnitude higher than that of the cladding waveguide (∼104 W/cm2).

  3. The impact of thermal treatment and cooling methods on municipal solid waste incineration bottom ash with an emphasis on Cl. (United States)

    Yang, Shuo; Saffarzadeh, Amirhomayoun; Shimaoka, Takayuki; Kawano, Takashi; Kakuta, Yoshitada


    Municipal solid waste incineration (MSWI) bottom-ash products possess qualifications to be utilized in cement production. However, the instant use of bottom ash is inhibited by a number of factors, among which the chlorine (Cl) content is always strictly restricted. In this paper, the unquenched MSWI bottom ash was used as the experimental substance, and the influences of thermal treatment and cooling methods on the content and existence of Cl in the ash residues were investigated. The characterization of the MSWI bottom-ash samples examined by utilizing X-ray diffraction, optical microscopy, scanning electron microscopy/energy dispersive X-ray spectroscopy. The experimental results show that as a function of thermal treatment, the reduction rate of Cl is slight below 15.0%, which is relatively low compared with water washing process. Different cooling methods had impacts on the existing forms of Cl. It was understood that most of Cl existed in the glass phase if the bottom ash was air cooled. Contrarily in case of water-quenched bottom ash, Cl could also be accumulated in the newly-formed quench products as chloride salts or hydrate substances such as Friedel's salt.

  4. 高压下NH4ClO4结构、电子及弹性性质的第一性原理研究%First principles investigations of structural, electronic and elastic prop erties of ammonium p erchlorate under high pressures

    Institute of Scientific and Technical Information of China (English)

    刘博; 王煊军; 卜晓宇


    Ammonium perchlorate (NH4ClO4) is a highly energetic oxidizer widely used in solid propellants and explosives. Under extreme pressure conditions, significant changes are observed in the structures and properties of NH4ClO4. How-ever, many studies of structural transformations of NH4 ClO4 under high pressures have not formed a more consistent conclusion. In this study, the structural, electronic, and elastic properties of NH4ClO4 are investigated by first-principles calculations based on the density functional theory with dispersion correction (DFT-D) method in a range of 0–15 GPa. The unit cell volume and lattice parameters are optimized by GGA/PBE-TS, which leads to good agreement with the experimental structure parameters at 0 GPa, suggesting the reliability of the present calculation method. The calculated P-V data are fitted to the third-order Birch-Murnaghan equation of state, and the result provides better agreement with experimental result than other calculations for the unit cell with a volume V0 and bulk moduli B0 and B′. The comprehensive analyses of the lattice parameters, bond lengths, and hydrogen bonds under high pressure indicate that three structural transformations occur in NH4ClO4 at 1 GPa, 4 GPa, and 9 GPa. With increasing pressure, hydrogen bonding interaction gradually increases, and intra- and intermolecular hydrogen bonds are present in crystals. Results obtained from the band structures and state densities under high pressure indicate that NH4ClO4 exhibits good insu-lating properties. Valence band shifts towards low energy, conduction band shifts towards high energy, and electronic localization is enhanced. The charge density differences and Mulliken charge populations at different pressures reveal that the covalent interaction between the N—H and Cl—O bonds increases, and the ionicity of crystal decreases. The band gaps in different structural transition regions exhibit different linear increase trends with increasing pressure. The

  5. Optical and electrostatic potential investigations of electrical breakdown phenomena in a low-pressure gas discharge lamp (United States)

    Gendre, M. F.; Haverlag, M.; Kroesen, G. M. W.


    The ignition phase is a critical stage in the operation of gas discharge lamps where the neutral gas enclosed between the electrodes undergoes a transformation from the dielectric state to a conducting phase, eventually enabling the production of light. The phenomena occurring during this phase transition are not fully understood and the related experimental studies are often limited to local optical measurements in environments prone to influencing these transient phenomena. In this work unipolar ignition phenomena at sub-kilovolt levels are investigated in a 3 Torr argon discharge tube. The lamp is placed in a highly controlled environment so as to prevent any bias on the measurements. A fast intensified CCD camera and a specially designed novel electrostatic probe are used simultaneously so as to provide a broad array of measured and computed parameters which are displayed in space-time diagrams for cross comparisons. Experiments show that three distinct phases exist during successful ignitions: upon the application of voltage a first ionization wave starts from the active electrode and propagates in the neutral gas towards the opposite electrode. A local front of high axial E field strength is associated with this process and causes a local ionization to occur, leading to the electrostatic charging of the lamp. Next, a second wave propagates from the ground electrode back towards the active electrode with a higher velocity, and in this process leads to a partial discharging of the lamp. This return stroke draws a homogeneous plasma column which eventually bridges both electrodes at the end of the wave propagation. At this point both electrode sheaths are formed and the common features of a glow discharge are observed. The third phase is an increase in the light intensity of the plasma column until the lamp reaches a steady-state operation. Failed ignitions present only the first phase where the first wave starts its propagation but extinguishes in the lamp

  6. Role of CO2 in the initial stage of atmospheric corrosion of AZ91 magnesium alloy in the presence of NaCl

    Institute of Scientific and Technical Information of China (English)


    The effect of CO2 and NaCl on the initial stage of atmospheric corrosion of AZ91 magnesium alloy was studied.The observation of surface morphology by optical microscopy (OM), scanning electron microscopy (SEM) and the analysis of corrosion products by X-ray diffraction (XRD) were integrated to investigate corrosion evolution. The results showed that NaCl stimulated the corrosion by promoting the formation of thin electrolyte film, increasing the conductivity and breaking the protective film in the absence of CO2. The morphology of the corroded samples with deposited NaCl was more homogenous in the presence of CO2. It was suggested that NaCl-induced corrosion was inhibited in the presence of CO2 by the formation of slightly soluble corrosion products containing hydroxy carbonates and hydroxy chlorides that provided a partly protective layer on the surface of the magnesium alloy.

  7. Investigation on an evanescent wave fiber-optic absorption sensor based on fiber loop cavity ring-down spectroscopy (United States)

    Jiang, Meng; Zhang, Weigang; Zhang, Qi; Liu, Yaping; Liu, Bo


    An improved ring-down measurement principle for optical waveguides is presented. Fiber loop ring-down spectroscopy allows for measurement of minute optical losses in high-finesse fiber-optic cavities and immunity to the fluctuation of laser source. The evanescent wave absorption losses dependent on the absorption and the refractive index of ambient solution have been theoretically analyzed. The complex refractive index is introduced into our model and extinction coefficient can be calculated accurately through finite element analysis by setting the boundaries of the fiber and the ambient conditions. Using this method, the refractive index of environment can be taken into consideration. Our principle is validated by the highly-sensitive measurement of evanescent wave absorption loss. By chemically processing the surface of sensing segment along an extending ring-down cavity, the concentration of small volume Diethyl Sulphoxide solution where the etched fiber immersed into has been successfully measured and discussed.

  8. Investigations on growth morphology, bulk growth and crystalline perfection of L-threonine, an organic nonlinear optical material

    Energy Technology Data Exchange (ETDEWEB)

    Linet, J. Mary [Department of Physics, Loyola College, Nungambakkam, Chennai 600 034 (India); Das, S. Jerome, E-mail: [Department of Physics, Loyola College, Nungambakkam, Chennai 600 034 (India)


    L-threonine single crystal was successfully grown from aqueous solution. The morphology of the grown crystal was compared with the predicted morphology using Bravais-Friedel-Donnay-Harker law and was found to be in good agreement with the predicted morphology. Good optical quality bulk single crystal of enhanced size has been grown using unidirectional crystal growth method. High-resolution X-ray analysis study resulted in a rocking curve with a full width half maximum of 20 arc sec exhibiting the good crystalline quality of the grown crystal. The optical transmission study shows 90% of transmission in the entire visible region that exhibits the good optical quality of the grown crystal. The mechanical properties were analyzed by Vicker's microhardness method.

  9. Investigation of Precursor Superconducting State in YBa2Cu3O7-δ through In-Plane Optical Spectroscopy (United States)

    Lee, Kegan; Kamiya, Keisuke; Nakajima, Masamichi; Miyasaka, Shigeki; Tajima, Setsuko


    A precursor of superconductivity has been searched in the in-plane optical spectra of underdoped YBa2Cu3Oy, in which the previous c-axis optical spectra showed the presence of superconducting carriers at a temperature far above Tc [Uykur et al.," xlink:type="simple">Phys. Rev. Lett. 112, 127003 (2014)][Dubroka et al.," xlink:type="simple">Phys. Rev. Lett. 106, 047006 (2011)]. By carefully subtracting the normal component from the imaginary part of conductivity σ2(ω), we found a clear in-plane response of superconducting condensate at the temperature consistent with the c-axis optical data. This confirms that the precursory superconductivity developing with decreasing doping level is an intrinsic phenomenon in the cuprates.

  10. Damage investigation on tungsten and diamond diffractive optics at a hard x-ray free-electron laser. (United States)

    Uhlén, Fredrik; Nilsson, Daniel; Holmberg, Anders; Hertz, Hans M; Schroer, Christian G; Seiboth, Frank; Patommel, Jens; Meier, Vivienne; Hoppe, Robert; Schropp, Andreas; Lee, Hae Ja; Nagler, Bob; Galtier, Eric; Krzywinski, Jacek; Sinn, Harald; Vogt, Ulrich


    Focusing hard x-ray free-electron laser radiation with extremely high fluence sets stringent demands on the x-ray optics. Any material placed in an intense x-ray beam is at risk of being damaged. Therefore, it is crucial to find the damage thresholds for focusing optics. In this paper we report experimental results of exposing tungsten and diamond diffractive optics to a prefocused 8.2 keV free-electron laser beam in order to find damage threshold fluence levels. Tungsten nanostructures were damaged at fluence levels above 500 mJ/cm(2). The damage was of mechanical character, caused by thermal stress variations. Diamond nanostructures were affected at a fluence of 59 000 mJ/cm(2). For fluence levels above this, a significant graphitization process was initiated. Scanning Electron Microscopy (SEM) and µ-Raman analysis were used to analyze exposed nanostructures.

  11. Analytical Investigations on Carrier Phase Recovery in Dispersion-Unmanaged n-PSK Coherent Optical Communication Systems


    Tianhua Xu; Gunnar Jacobsen; Sergei Popov; Jie Li; Tiegen Liu; Yimo Zhang; Polina Bayvel


    Using coherent optical detection and digital signal processing, laser phase noise and equalization enhanced phase noise can be effectively mitigated using the feed-forward and feed-back carrier phase recovery approaches. In this paper, theoretical analyses of feed-back and feed-forward carrier phase recovery methods have been carried out in the long-haul high-speed n-level phase shift keying (n-PSK) optical fiber communication systems, involving a one-tap normalized least-mean-square (LMS) al...

  12. Growth and optical investigations of high quality individual CdTe/(Cd,Mg)Te core/shell nanowires (United States)

    Wojnar, P.; Płachta, J.; Kret, S.; Kaleta, A.; Zaleszczyk, W.; Szymura, M.; Wiater, M.; Baczewski, L. T.; Pietruczik, A.; Karczewski, G.; Wojtowicz, T.; Kossut, J.


    CdTe nanowires with the average diameter of only 40 nm coated with (Cd,Mg)Te shells are grown using Au-catalyzed vapor-liquid-solid growth mechanism in a system for molecular beam epitaxy. High optical quality of individual nanowires is revealed by means of low temperature cathodoluminescence and micro-luminescence. It is found that, the optical emission spectrum consists mostly of the near band edge emission without any significant contribution of defect related luminescence. Moreover, the importance of surface passivation with (Cd,Mg)Te coating shells is demonstrated.

  13. Structural, spectroscopic, and multiconfigurational quantum chemical investigations of the electron-rich metal-metal triple-bonded Tc(2)X(4)(PMe(3))(4) (X = Cl, Br) complexes. (United States)

    Poineau, Frederic; Forster, Paul M; Todorova, Tanya K; Gagliardi, Laura; Sattelberger, Alfred P; Czerwinski, Kenneth R


    The compounds Tc(2)Cl(4)(PMe(3))(4) and Tc(2)Br(4)(PMe(3))(4) were formed from the reaction between (n-Bu(4)N)(2)Tc(2)X(8) (X = Cl, Br) and trimethylphosphine. The Tc(II) dinuclear species were characterized by single-crystal XRD, UV-visible spectroscopy, and cyclic voltammetry techniques, and the results are compared to those obtained from density functional theory and multiconfigurational (CASSCF/CASPT2) quantum chemical studies. The compound Tc(2)Cl(4)(PMe(3))(4) crystallizes in the monoclinic space group C2/c [a = 17.9995(9) A, b = 9.1821(5) A, c = 17.0090(9) A, beta = 115.4530(10) degrees ] and is isostructural to M(2)Cl(4)(PMe(3))(4) (M = Re, Mo, W) and to Tc(2)Br(4)(PMe(3))(4). The metal-metal distance (2.1318(2) A) is similar to the one found in Tc(2)Br(4)(PMe(3))(4) (2.1316(5) A). The calculated molecular structures of the ground states are in excellent agreement with the structures determined experimentally. Calculations of effective bond orders for Tc(2)X(8)(2-) and Tc(2)X(4)(PMe(3))(4) (X = Cl, Br) indicate stronger pi bonds in the Tc(2)(4+) core than in Tc(2)(6+) core. The electronic spectra were recorded in benzene and show a series of low intensity bands in the range 10 000-26 000 cm(-1). Assignment of the bands as well as computing their excitation energies and intensities were performed at both TD-DFT and CASSCF/CASPT2 levels of theory. Calculations predict that the lowest energy band corresponds to the delta* --> sigma* transition, the difference between calculated and experimental values being 228 cm(-1) for X = Cl and 866 cm(-1) for X = Br. The next bands are attributed to delta* --> pi*, delta --> sigma*, and delta --> pi* transitions. The cyclic voltammograms exhibit two reversible waves and indicate that Tc(2)Br(4)(PMe(3))(4) exhibits more positive oxidation potentials than Tc(2)Cl(4)(PMe(3))(4.) This phenomenon is discussed and ascribed to stronger metal (d) to halide (d) back bonding in the bromo complex. Further analysis indicates that Tc

  14. Impact of intraocular pressure on changes of blood flow in the retina, choroid, and optic nerve head in rats investigated by optical microangiography. (United States)

    Zhi, Zhongwei; Cepurna, William O; Johnson, Elaine C; Morrison, John C; Wang, Ruikang K


    In this paper, we demonstrate the use of optical coherence tomography/optical microangiography (OCT/OMAG) to image and measure the effects of acute intraocular pressure (IOP) elevation on retinal, choroidal and optic nerve head (ONH) perfusion in the rat eye. In the experiments, IOP was elevated from 10 to 100 mmHg in 10 mmHg increments. At each IOP level, three-dimensional data volumes were captured using an ultrahigh sensitive (UHS) OMAG scanning protocol for 3D volumetric perfusion imaging, followed by repeated B-scans for Doppler OMAG analysis to determine blood flow velocity. Velocity and vessel diameter measurements were used to calculate blood flow in selected retinal blood vessels. Choroidal perfusion was calculated by determining the peripapillary choroidal filling at each pressure level and calculating this as a percentage of area filling at baseline (10 mmHg). ONH blood perfusion was calculated as the percentage of blood flow area over a segmented ONH area to a depth 150 microns posterior to the choroidal opening. We show that volumetric blood flow reconstructions revealed detailed 3D maps, to the capillary level, of the retinal, choroidal and ONH microvasculature, revealing retinal arterioles, capillaries and veins, the choroidal opening and a consistent presence of the central retinal artery inferior to the ONH. While OCT structural images revealed a reversible compression of the ONH and vasculature with elevated IOP, OMAG successfully documented changes in retinal, choroidal and ONH blood perfusion and allowed quantitative measurements of these changes. Starting from 30 mm Hg, retinal blood flow (RBF) diminished linearly with increasing IOP and was nearly extinguished at 100 mm Hg, with full recovery after return of IOP to baseline. Choroidal filling was unaffected until IOP reached 60 mmHg, then decreased to 20% of baseline at IOP 100 mmHg, and normalized when IOP returned to baseline. A reduction in ONH blood perfusion at higher IOP's was also

  15. Dynamic Reaction Mechanisms of ClO(-) with CH3Cl: Comparison Between Direct Dynamics Trajectory Simulations and Experiment. (United States)

    Yu, Feng


    We have investigated the dynamic reaction mechanisms of *ClO¯ with CH3Cl (the asterisk is utilized to label a different Cl atom). Ab initio molecular dynamics simulations at the MP2/6-31+G(d,p) level of theory have been employed to compute the dynamic trajectories. On the basis of our simulations, the dynamic reaction pathways for the bimolecular nucleophilic substitution (SN2) reaction channel and SN2-induced elimination reaction channel are clearly illustrated. For the SN2 reaction channel, some trajectories directly dissociate to the final products of CH3O*Cl and Cl¯, whereas the others involve the dynamic Cl¯···CH3O*Cl intermediate complex. As to the SN2-induced elimination reaction channel, the trajectories lead to the final products of CH2O, HCl, and *Cl¯ through the dynamic Cl¯···CH3O*Cl intermediate complex. More significantly, the product branching ratios of Cl¯ and *Cl¯ predicted by our simulations are basically consistent with previous experimental results (Villano et al. J. Am. Chem. Soc. 2009, 131, 8227-8233).

  16. Desfechos clínicos após investigação para Embolia Pulmonar utilizando TC de tórax/membros inferiores Clinical outcomes after investigation for pulmonary embolism using CT angiography and venography

    Directory of Open Access Journals (Sweden)

    Eduardo S. Darze


    Full Text Available FUNDAMENTO: O diagnóstico de Embolia Pulmonar (EP ainda requer longos períodos de trabalho e inúmeros testes. OBJETIVO: Nosso objetivo é avaliar os desfechos clínicos após uma investigação negativa usando um protocolo combinado de angio TC de tórax e venografia por TC (CTA/CTV como único teste de diagnóstico em pacientes não selecionados com suspeita de EP. MÉTODOS: Estudo de coorte retrospectivo que incluiu pacientes consecutivos com suspeita de EP que foram investigados com um protocolo combinado de CTA/CTV. Os pacientes que apresentaram inicialmente uma investigação negativa e não receberam anticoagulantes foram acompanhados por seis meses para ocorrência de eventos tromboembólicos venosos recorrentes. RESULTADOS: De 425 pacientes com suspeita de EP, 62 (14,6% tiveram diagnóstico de tromboembolismo venoso no CTA/CTV inicial. A média de idades foi de 56 ± 19 anos, e 61% da população se enquadravam na categoria de baixa probabilidade clínica. A trombose venosa profunda isolada representou 21% de todos os eventos tromboembólicos venosos, e quando se considerou toda a população, a CTV foi associada a um incremento no rendimento diagnóstico de 3,1%. Nosso grupo era composto de 320 pacientes com CTA/CTV inicialmente negativo e que não receberam anticoagulantes. Após seis meses de acompanhamento, apenas três pacientes apresentaram recorrência de eventos tromboembólicos (0,9%, IC 95% -0,1% - 2,0% e nenhum foi fatal. Não houve mortes relacionadas com a EP. CONCLUSÕES: Nosso estudo sugere que uma estratégia de diagnóstico que utiliza CTA/CTV como único teste de diagnóstico pode descartar EP com segurança, em população com risco baixo a moderado, e está associada a resultados favoráveis, com um valor preditivo negativo de 99,1%. (Arq Bras Cardiol. 2012; [online].ahead print, PP.0-0BACKGROUND: The diagnosis of pulmonary embolism (PE still requires long work-up periods and multiple tests. OBJECTIVE: We aim to

  17. Emergence of Bulk CsCl Structure in $(CsCl)_{n}Cs^{+}$ Cluster Ions

    CERN Document Server

    Aguado, A


    The emergence of CsCl bulk structure in (CsCl)nCs+ cluster ions is investigated using a mixed quantum-mechanical/semiempirical theoretical approach. We find that rhombic dodecahedral fragments (with bulk CsCl symmetry) are more stable than rock-salt fragments after the completion of the fifth rhombic dodecahedral atomic shell. From this size (n=184) on, a new set of magic numbers should appear in the experimental mass spectra. We also propose another experimental test for this transition, which explicitely involves the electronic structure of the cluster. Finally, we perform more detailed calculations in the size range n=31--33, where recent experimental investigations have found indications of the presence of rhombic dodecahedral (CsCl)32Cs+ isomers in the cluster beams.

  18. Investigation of optical spacer layers from solution based precursors for polymer solar cells using X-ray reflectometry

    DEFF Research Database (Denmark)

    Andersen, Philip Hvidthøft Delff; Skårhøj, Jakob; Andreasen, Jens Wenzel


    Optical spacer layers based on titaniumalkoxide precursor solutions were prepared by spin-coating on top of bulk heterojunction layers based on poly-3-hexylthiophene (P3HT) and phenyl-C61-butyric acid methylester (PCBM). Models and experiment have shown that the performance of polymer solar cells...

  19. Experimental Investigation of transmission properties of all-optical label swapping of orthogonal IM/FSK labeled signals

    DEFF Research Database (Denmark)

    Holm-Nielsen, Pablo Villanueva; Chi, Nan; Zhang, Jianfeng;


    Optically labeled IM/FSK signal saretran smitte dover 50km of SMF under different compensation schemes.All-opticallabel swapping based on MZ-SOA and EAM is presented. Transmission followed by label swapping shows a 2dB overall power penalty....

  20. Experimental Investigation of Transmission Properties and All-Optical Label Swapping of Orthogonal IM/FSK Labeled Signals

    Institute of Scientific and Technical Information of China (English)

    Pablo V. Holm-Nielsen; Nan Chi; Jianfeng Zhang; Christophe Peucheret; Idelfonso Tafur Monroy; Palle Jeppesen


    Optically labeled IM/FSK signal saretran smitte dover 50km of SMF under different compensation schemes.All-opticallabel swapping based on MZ-SOA and EAM is presented. Transmission followed by label swapping shows a 2dB overall power penalty.

  1. Experimental Investigation of Pump-to-Signal Noise Transfer in One-Pump Phase Insensitive Fibre Optic Parametric Amplifiers

    DEFF Research Database (Denmark)

    Cristofori, Valentina; Lund-Hansen, Toke; Peucheret, Christophe


    This paper presents a detailed experimental characterization of the relative intensity noise (RIN) transferred from the pump to the signal in one-pump phase insensitive fibre optic parametric amplifiers. We extend an existing experimental and theoretical work towards higher frequencies, showing...

  2. Extending the area of investigation of fine versus coarse quartz optical ages from the Lower Danube to the Carpathian Basin

    DEFF Research Database (Denmark)

    Timar-Gabor, Alida; Constantin, Daniela; Marković, S.B.;


    Despite the general satisfactory performance of quartz in the single aliquot regeneration protocol (SAR), previous optically stimulated luminescence (OSL) dating studies of key loess sections in Romania, Lower Danube region, revealed a disturbing disagreement among the ages obtained on fine (4e11...

  3. Optical investigation of the propagation of the amorphous-crystalline boundary in ion-beam irradiated LiNbO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Olivares, J. [Instituto de Optica ' Daza de Valdes' , CSIC, Serrano 121, 28006 Madrid (Spain); Garcia, G. [Centro de Microanalisis de Materiales, CMAM-UAM, Parque Cientifico de Madrid, Cantoblanco, E-28049 Madrid (Spain); Agullo-Lopez, F. [Centro de Microanalisis de Materiales, CMAM-UAM, Parque Cientifico de Madrid, Cantoblanco, E-28049 Madrid (Spain); Departamento de Fisica de Materiales, C-IV, Universidad Autonoma de Madrid, Cantoblanco, 28049 Madrid (Spain); Agullo-Rueda, F. [Instituto de Ciencia de Materiales de Madrid, CSIC, Cantoblanco, E-28049 Madrid (Spain); Soares, J.C. [Centro de Fisica Nuclear da Universidade de Lisboa, P-1649-003 Lisbon (Portugal); Kling, A. [Instituto Tecnologico e Nuclear (ITN), P-2685 Sacavem (Portugal)


    The effects of high-energy silicon (5 MeV, 7.5 MeV and 30 MeV) irradiations have been optically investigated by the dark-mode m-lines technique. In all cases, an optically isotropic homogeneous layer is created after a certain critical fluence that depends on ion and energy. The structure of the layer has been investigated by micro-Raman spectroscopy and RBS/channeling. The inner boundary of the layer separating the amorphous and crystalline regions moves into the crystal on increasing fluence. The results are discussed based on the occurrence of a sharp threshold in the electronic stopping power leading to the formation of overlapped latent (amorphous) tracks.

  4. 3D micro-particle image modeling and its application in measurement resolution investigation for visual sensing based axial localization in an optical microscope (United States)

    Wang, Yuliang; Li, Xiaolai; Bi, Shusheng; Zhu, Xiaofeng; Liu, Jinhua


    Visual sensing based three dimensional (3D) particle localization in an optical microscope is important for both fundamental studies and practical applications. Compared with the lateral (X and Y) localization, it is more challenging to achieve a high resolution measurement of axial particle location. In this study, we aim to investigate the effect of different factors on axial measurement resolution through an analytical approach. Analytical models were developed to simulate 3D particle imaging in an optical microscope. A radius vector projection method was applied to convert the simulated particle images into radius vectors. With the obtained radius vectors, a term of axial changing rate was proposed to evaluate the measurement resolution of axial particle localization. Experiments were also conducted for comparison with that obtained through simulation. Moreover, with the proposed method, the effects of particle size on measurement resolution were discussed. The results show that the method provides an efficient approach to investigate the resolution of axial particle localization.

  5. Intelligent Optics Laboratory (United States)

    Federal Laboratory Consortium — The Intelligent Optics Laboratory supports sophisticated investigations on adaptive and nonlinear optics; advancedimaging and image processing; ground-to-ground and...

  6. Optical transmittance investigation of 1-keV ion-irradiated sapphire crystals as potential VUV to NIR window materials of fusion reactors

    Directory of Open Access Journals (Sweden)

    Keisuke Iwano


    Full Text Available We investigate the optical transmittances of ion-irradiated sapphire crystals as potential vacuum ultraviolet (VUV to near-infrared (NIR window materials of fusion reactors. Under potential conditions in fusion reactors, sapphire crystals are irradiated with hydrogen (H, deuterium (D, and helium (He ions with 1-keV energy and ∼ 1020-m-2 s-1 flux. Ion irradiation decreases the transmittances from 140 to 260 nm but hardly affects the transmittances from 300 to 1500 nm. H-ion and D-ion irradiation causes optical absorptions near 210 and 260 nm associated with an F-center and an F+-center, respectively. These F-type centers are classified as Schottky defects that can be removed through annealing above 1000 K. In contrast, He-ion irradiation does not cause optical absorptions above 200 nm because He-ions cannot be incorporated in the crystal lattice due to the large ionic radius of He-ions. Moreover, the significant decrease in transmittance of the ion-irradiated sapphire crystals from 140 to 180 nm is related to the light scattering on the crystal surface. Similar to diamond polishing, ion irradiation modifies the crystal surface thereby affecting the optical properties especially at shorter wavelengths. Although the transmittances in the VUV wavelengths decrease after ion irradiation, the transmittances can be improved through annealing above 1000 K. With an optical transmittance in the VUV region that can recover through simple annealing and with a high transparency from the ultraviolet (UV to the NIR region, sapphire crystals can therefore be used as good optical windows inside modern fusion power reactors in terms of light particle loadings of hydrogen isotopes and helium.

  7. Laser deposition and optical investigation of thin Ga(x)In(1-x)As(y)Sb(1-y) films of different compositions

    Energy Technology Data Exchange (ETDEWEB)

    Avdzhian, K.E.; Aleksanian, A.G.; Kazarian, R.K.; Matevosian, L.A.; Mirzabekian, G.E.


    Films of GaInAsSb solid solutions, obtained by the laser mixing method, are investigated. The lattice parameters and film compositions are determined, and the corresponding forbidden zone widths are found to be in good agreement with the values obtained in an optical study. The spectral dependence of the quantum well effect observed for a 29-nm-thick film is consistent with the analytical expression proposed here. 5 references.

  8. Isopiestic Investigation of the Osmotic and Activity Coefficients of {yMgCl2 + (1 - y)MgSO4}(aq) and the Osmotic Coefficients of Na2SO4.MgSO4(aq) at 298.15 K

    Energy Technology Data Exchange (ETDEWEB)

    Miladinovic, J; Ninkovic, R; Todorovic, M; Rard, J A


    Isopiestic vapor pressure measurements were made for {l_brace}yMgCl{sub 2} + (1-y)MgSO{sub 4}{r_brace}(aq) solutions with MgCl{sub 2} ionic strength fractions of y = 0, 0.1997, 0.3989, 0.5992, 0.8008, and (1) at the temperature 298.15 K, using KCl(aq) as the reference standard. These measurements for the mixtures cover the ionic strength range I = 0.9794 to 9.4318 mol {center_dot} kg{sup -1}. In addition, isopiestic measurements were made with NaCl(aq) as reference standard for mixtures of {l_brace}xNa{sub 2}SO{sub 4} + (1-x)MgSO{sub 4}{r_brace}(aq) with the molality fraction x = 0.50000 that correspond to solutions of the evaporite mineral bloedite (astrakanite), Na{sub 2}Mg(SO{sub 4}){sub 2} {center_dot} 4H{sub 2}O(cr). The total molalities, m{sub T} = m(Na{sub 2}SO{sub 4}) + m(MgSO{sub 4}), range from m{sub T} = 1.4479 to 4.4312 mol {center_dot} kg{sup -1} (I = 5.0677 to 15.509 mol {center_dot} kg{sup -1}), where the uppermost concentration is the highest oversaturation molality that could be achieved by isothermal evaporation of the solvent at 298.15 K. The parameters of an extended ion-interaction (Pitzer) model for MgCl2(aq) at 298.15 K, which were required for an analysis of the {l_brace}yMgCl{sub 2} + (1-y)MgSO{sub 4}{r_brace}(aq) mixture results, were evaluated up to I = 12.025 mol {center_dot} kg{sup -1} from published isopiestic data together with the six new osmotic coefficients obtained in this study. Osmotic coefficients of {l_brace}yMgCl{sub 2} + (1-y)MgSO{sub 4}{r_brace}(aq) solutions from the present study, along with critically-assessed values from previous studies, were used to evaluate the mixing parameters of the extended ion-interaction model.

  9. First-Principles Study on Electronic Structures and Optical Properties of Doped Ag Crystal

    Institute of Scientific and Technical Information of China (English)

    CAO Can; CHEN Ling-Na; JIA Shu-Ting; ZHANG Dan; XU Hui


    By using the first-principles calculation based on density functional theory,we investigate the electronic structures and optical properties of Cl-doped Ag crystal. The results show that the electronic structure of Cl-doped Ag crystal depends on the doped concentration and the site of impurity defect.Interestingly,the calculated adsorption spectra of Cl-doped Ag crystal show isotropy or anisotropy coincide with the symmetry of Ag crystal. These features are discussed to provide guidance to experimental efforts for Ag-based nanoeletronic devices.

  10. Instrumental intercomparison investigating vertical profiles of optical turbulence and wind speed in the lower atmospheric boundary layer during frontal passages in northwestern Germany (United States)

    Sprung, Detlev; Stein, Karin; Sucher, Erik; Englander, Abraham; Fastig, Salomon; Porat, Omar


    The German-Israeli intercomparison experiment on the investigation of vertical profiles of horizontal wind speed and optical turbulence in the lower atmospheric boundary layer from 4th to 7th May 2015 was characterized by frontal activity in the atmosphere. The newly developed remote LIDAR-device of the Soreq institute for the investigation of the vertical wind and turbulence field was compared to the routinely performed measurements at the VerTurM (Vertical Turbulence Measurements) field site in Meppen, Germany. The long-term experiment VerTurM is focused on measurements of the optical turbulence and comprises scintillometer measurements close to the ground (1.15 m height), sonic anemometer measurements on a tall tower at 4 m, 8 m, 32 m, and 64 m and a SODAR-RASS-system. The temporal development of the vertical profiles of horizontal wind speed and optical turbulence Cn 2 during the frontal passage is investigated. Additional radiosonde measurements were performed to characterize the boundary layer height during the day.

  11. Excitons and biexcitons in CuCl nanocrystallites

    Energy Technology Data Exchange (ETDEWEB)

    Hoenerlage, B. [Institut de Physique et Chimie des Materiaux, Strasbourg (France). Groupe d`Optique Nonlineaire et d`Optoelectronique; Levy, R. [Institut de Physique et Chimie des Materiaux, Strasbourg (France). Groupe d`Optique Nonlineaire et d`Optoelectronique; Grun, J.B. [Institut de Physique et Chimie des Materiaux, Strasbourg (France). Groupe d`Optique Nonlineaire et d`Optoelectronique


    Because of the important binding energies of excitons and biexcitons in CuCl, these elementary excitations can be treated in the weak confinement regime if excited in semiconductor nanocrystallites. Their optical properties and dynamics are similar to those of CuCl bulk material. Besides the well-known blue shift of resonances due to the confinement and their inhomogeneous broadening due to the size distribution of the nanocrystallites, the main difference between both systems results from surface effects and the lack of translational invariance in nanocrystallites. The latter affects the selection rules of optical transitions and the exchange interaction of the quasiparticules. (orig.).

  12. Initial investigation of the wavelength dependence of optical properties measured with a new multi-pass aerosol extinction differential optical absorption spectrometer (AE-DOAS

    Directory of Open Access Journals (Sweden)

    R. T. Chartier


    Full Text Available Atmospheric aerosols directly affect climate by scattering and absorbing radiation. The magnitude of the impact is dependent upon the wavelength of light, but is often estimated near 550 nm. When light scattering and absorption by aerosols is approximated, the wavelength dependence of the refractive index for specific components is lost. As a result, climate models would have inherent uncertainties for aerosol contributions to radiative forcing when considering the entire solar spectrum. An aerosol extinction differential optical absorption spectrometer has been developed to directly measure aerosol extinction at mid-ultraviolet to near infrared wavelengths. The instrument consists of a spectrometer coupled to a closed White-type multi-pass gas cell with an adjustable path length of up to approximately 20 m. Laboratory measurements of various gases are compared with known absorption cross sections. Additionally, the extinction of monodisperse samples of polystyrene latex spheres are measured and compared to Mie theory generated with refractive index values from the literature to validate the new instrument. The polystyrene experiments also emphasize the ability of the new instrument to retrieve the wavelength dependent refractive index, especially in the ultraviolet wavelength regions where variability is expected. The spectrometer will be a significant advancement for determining wavelength dependent complex refractive indices in future laboratory studies as well as provide the ability to monitor ambient aerosol light extinction.

  13. Initial investigation of the wavelength dependence of optical properties measured with a new multi-pass Aerosol Extinction Differential Optical Absorption Spectrometer (AE-DOAS

    Directory of Open Access Journals (Sweden)

    R. T. Chartier


    Full Text Available Atmospheric aerosols directly affect climate by scattering and absorbing radiation. The magnitude of the impact is dependent upon the wavelength of light, but is often estimated near 550 nm. When light scattering and absorption by aerosols is approximated, the wavelength dependence of the refractive index for specific components is lost. As a result, climate models would have inherent uncertainties for aerosol contributions to radiative forcing when considering the entire solar spectrum. An aerosol extinction differential optical absorption spectrometer has been developed to directly measure aerosol extinction at mid-ultraviolet to near infrared wavelengths. The instrument consists of a spectrometer coupled to a closed White-type multi-pass gas cell with an adjustable path length of up to approximately 20 m. Laboratory measurements of various gases are compared with known absorption cross sections. Additionally, the extinction of monodisperse samples of polystyrene latex spheres are measured and compared to Mie theory generated with refractive index values from the literature to validate the new instrument. The polystyrene experiments also emphasize the ability of the new instrument to retrieve the wavelength dependent refractive index, especially in the ultraviolet wavelength regions where variability is expected. The spectrometer will be a significant advancement for determining wavelength dependent complex refractive indices in future laboratory studies as well as provide the ability to monitor ambient aerosol light extinction.

  14. Importance of the Electrolyte in Obtaining Porous Silicon and How It Modifies the Optical and Structural Proprieties: Optical and Microstructural Investigation

    Directory of Open Access Journals (Sweden)

    F. Severiano


    Full Text Available The effect of using different electrolytes in the physical and optical properties of porous silicon was studied. To do this porous silicon (PS samples photoluminescent in the visible range from (100 oriented n-type crystalline silicon prepared by anodic etching were obtained. The first electrolyte was composed of a mixture of hydrofluoric acid (HF and ethanol (CH3-CH2-OH in a ratio of 1 : 2, respectively. The second was composed of hydrofluoric acid (HF, ethanol (CH3-CH2-OH, and hydrogen peroxide (H2O2 in a ratio of 1 : 1 : 2, respectively. Raman scattering, photoluminescence (PL, gravimetry, scanning electron microscopy (SEM, and energy dispersive spectrometer (EDS measurements on the PSL were carried out. Raman scattering showed that the disorder in the samples obtained with H2O2 is greater than in the samples obtained without this. The PL from PS increased in intensity with the incremental change in the anodization time and showed a blueshift. The blueshift of PL is consistent with the reduction in size of the silicon nanocrystallites. The sizes of nanocrystals were estimated to be 3.08, 2.6, and 2.28 nm. The gravimetric analysis showed that the porosity increased with the incorporation of H2O2. SEM images (morphological analysis showed an incremental change in the quantity and in the porous size.

  15. Joint Reconstruction of Absorbed Optical Energy Density and Sound Speed Distribution in Photoacoustic Computed Tomography: A numerical Investigation

    CERN Document Server

    Huang, Chao; Schoonover, Robert W; Wang, Lihong V; Anastasio, Mark A


    Photoacoustic computed tomography (PACT) is a rapidly emerging bioimaging modality that seeks to reconstruct an estimate of the absorbed optical energy density within an object. Conventional PACT image reconstruction methods assume a constant speed-of-sound (SOS), which can result in image artifacts when acoustic aberrations are significant. It has been demonstrated that incorporating knowledge of an object's SOS distribution into a PACT image reconstruction method can improve image quality. However, in many cases, the SOS distribution cannot be accurately and/or conveniently estimated prior to the PACT experiment. Because variations in the SOS distribution induce aberrations in the measured photoacoustic wavefields, certain information regarding an object's SOS distribution is encoded in the PACT measurement data. Based on this observation, a joint reconstruction (JR) problem has been proposed in which the SOS distribution is concurrently estimated along with the sought-after absorbed optical energy density ...

  16. Theoretical Investigation on the Second-order Nonlinear Optical Properties of Chiral Amino Acid Zinc(Ⅱ) Porphyrins

    Institute of Scientific and Technical Information of China (English)

    LIU Hai-Yang; TIAN Jun-Chun; YING Xiao; XU Zhi-Guang; LIAO Shi-Jun; CHANG Chi-Kwong


    Static second-order nonlinear optical effects of amino acid zinc(II) porphyrins 1, 2, 3 and 4 were calculated by the TDHF/PM3 method based on the molecular structures optimized at the semiempirical PM3 quantum chemistry level, showing due to the cancellation of symmetric center, these amino acid zinc(II) porphyrins exhibit second order nonlinear optical response. The analysis of β components indicated that these amino acid zinc(II) porphyrins are of multipolarizabilities, and they may be ascribed as the "mixture" of octupolar and dipoar molecules with ||βJ=3||/||βJ=1|| ≈ 5. It is found that there are no significant differences between the static β values of non-chiral and chiral amino acid zinc(II) porphyrins. However, the βxyz component, which is quite important to quadratic macroscopic х (2) susceptibility of chiral material, is increased significantly with the increase of side chain group of amino acids.

  17. Parametric Investigation of Radome Analysis Methods. Volume II. Computer-Aided Radome Analysis Using Geometrical Optics and Lorentz Reciprocity. (United States)


    Read :ind \\’r it e TI’LE aceordi nq to, 18A.1 foiina t Li tier e 5-67: R-. nif iiitt dat a uO i ug free-field format. Line o : CORnII)’t " si no of the of...comjiut e C1 , L.’’ 17-1_1e,: c’all RXMIT and complUte tab, (it t iecsl.o-.ffi - coint ; versus sine of incidenice iiq. fl i rst c:il I to RXMIT bulx ds...0ZZ X x .j L c1 - X. -4 N p Z Z 4, -a a .0) a 4 wL- Z V~-X x 0* 1- /) 4 ty IC * Z 6. n .~ -4A14. 6 .- l-- IA I- w -4 >( ffa) CL L U-> Z~ z z z0D3- V

  18. Optical Distinctions Between Weyl Semimetal TaAs and Dirac Semimetal Na3Bi: An Ab Initio Investigation (United States)

    Dadsetani, Mehrdad; Ebrahimian, Ali


    We present ab initio a study on linear and nonlinear optical properties of topological semimetal Tantalum arsenide and Sodium bismuthate. The real and imaginary part of the dielectric function in addition to the energy loss spectra of TaAs and Na3Bi have been calculated within random phase approximation (RPA); then, the electron-hole interaction is included by solving the Bethe-Salpeter equation for the electron-hole Green's function. In spite of being in the single category of topological materials, we have found obvious distinction between linear optical responses of TaAs and Na3Bi at a high energy region where, in contrast to Na3Bi, Tantalum arsenide has excitonic peaks at 9 eV and 9.5 eV. It is remarkable that the excitonic effects in the high energy range of the spectrum are stronger than in the lower one. The dielectric function is overall red shifted compared with that of RPA approximation. The resulting static dielectric constants for Na3Bi are smaller than corresponding ones in TaAs. At a low energy region, the absorption intensity of TaAs is more than Na3Bi. The calculated second-order nonlinear optical susceptibilities χ ijk (2) ( ω) show that Tantalum arsenide acts as a Weyl semimetal, and has high values of nonlinear responses in the low energy region which makes it promising candidate for the second harmonic generation in the terahertz frequency region. In the low energy regime, optical spectra are dominated by the 2 ω intra-band contributions.

  19. Investigation on the linear and nonlinear optical properties of a metal organic complex—Bis thiourea zinc acetate single crystal (United States)

    Pabitha, G.; Dhanasekaran, R.


    The third order nonlinear optical properties of bis thiourea zinc acetate single crystal were measured using He-Ne laser (λ=632.8nm) by employing the Z-scan technique. The magnitude of nonlinear refractive index and nonlinear absorption coefficient were found to be -2.11×10-8cm2/W and -1.201×10-3cm/W respectively. The linear refractive index of the complex was measured by the Brewster angle method and was found to be 1.483. The third order non-linear optical susceptibility χ(3) was found to be in the order of 10-6esu. The negative non-linear absorption coefficient shows the defocusing nature of the complex which is an essential property required for the application in optical limiting application. The second harmonic generation efficiency of the complex was studied using the Powder Kurtz method and was found to be 1.5 times greater than that of KDP.

  20. Investigations on crystalline structure and optical band gap of nearly stoichiometric LiNbO3 nanoparticles (United States)

    Debnath, C.; Kar, S.; Verma, S.; Bartwal, K. S.


    The structural and optical characteristics of nearly stoichiometric lithium niobate, LiNbO3 nanoparticles have been studied. The results are very different compared to the bulk LiNbO3 single crystals. The nanoparticles were synthesized by citrate gel method and the phase was confirmed by powder X-ray diffraction. The size and size distribution of the nanoparticles were obtained by XRD, SEM, TEM and DLS experiments. The particles were in the range of 50-200 nm and most of the particles are about 100 nm of size. The lattice parameters obtained from selected area electron diffraction are aH = 5.213 Å and cH = 14.026 Å for hexagonal system which are slightly larger than the other reported values (JCPDS). The optical properties were obtained from optical absorption spectroscopy in UV-vis.-NIR and IR (FTIR) range, the electronic band gap structure were determined from the fundamental absorption edge in the UV region. The indirect band gap was of 4.78 eV where as the direct gap was of 6.0 eV which are much larger than the other experimental values. The absorption features in the UV range indicate the discrete nature of conduction band and the allowed energy levels in the forbidden gap appeared due to surface defects.

  1. Investigation of aerosol optical properties for remote sensing through DRAGON (distributed regional aerosol gridded observation networks) campaign in Korea (United States)

    Lim, Jae-Hyun; Ahn, Joon Young; Park, Jin-Soo; Hong, You-Deok; Han, Jin-Seok; Kim, Jhoon; Kim, Sang-Woo


    Aerosols in the atmosphere, including dust and pollutants, scatters/absorbs solar radiation and change the microphysics of clouds, thus influencing the Earth's energy budget, climate, air quality, visibility, agriculture and water circulation. Pollutants have also been reported to threaten the human health. The present research collaborated with the U.S. NASA and the U.S. Aerosol Robotic Network (AERONET) is to study the aerosol characteristics in East Asia and improve the long-distance transportation monitoring technology by analyzing the observations of aerosol characteristics in East Asia during Distributed Regional Aerosol Gridded Observation Networks (DRAGON) Campaign (March 2012-May 2012). The sun photometers that measure the aerosol optical characteristics were placed evenly throughout the Korean Peninsula and concentrated in Seoul and the metropolitan area. Observation data are obtained from the DRAGON campaign and the first year (2012) observation data (aerosol optical depth and aerosol spatial distribution) are analyzed. Sun photometer observations, including aerosol optical depth (AOD), are utilized to validate satellite observations from Geostationary Ocean Color Imager (GOCI) and Moderate Resolution Imaging Spectroradiometer (MODIS). Additional analysis is performed associated with the Northeast Asia, the Korean Peninsula in particular, to determine the spatial distribution of the aerosol.

  2. Analytical Investigations on Carrier Phase Recovery in Dispersion-Unmanaged n-PSK Coherent Optical Communication Systems

    Directory of Open Access Journals (Sweden)

    Tianhua Xu


    Full Text Available Using coherent optical detection and digital signal processing, laser phase noise and equalization enhanced phase noise can be effectively mitigated using the feed-forward and feed-back carrier phase recovery approaches. In this paper, theoretical analyses of feed-back and feed-forward carrier phase recovery methods have been carried out in the long-haul high-speed n-level phase shift keying (n-PSK optical fiber communication systems, involving a one-tap normalized least-mean-square (LMS algorithm, a block-wise average algorithm, and a Viterbi-Viterbi algorithm. The analytical expressions for evaluating the estimated carrier phase and for predicting the bit-error-rate (BER performance (such as the BER floors have been presented and discussed in the n-PSK coherent optical transmission systems by considering both the laser phase noise and the equalization enhanced phase noise. The results indicate that the Viterbi-Viterbi carrier phase recovery algorithm outperforms the one-tap normalized LMS and the block-wise average algorithms for small phase noise variance (or effective phase noise variance, while the one-tap normalized LMS algorithm shows a better performance than the other two algorithms for large phase noise variance (or effective phase noise variance. In addition, the one-tap normalized LMS algorithm is more sensitive to the level of modulation formats.

  3. Reactive magnetron sputtering of Ni doped ZnO thin film: Investigation of optical, structural, mechanical and magnetic properties

    Energy Technology Data Exchange (ETDEWEB)

    Siddheswaran, R., E-mail: [New Technologies Research Centre, University of West Bohemia, Plzeň 30614 (Czech Republic); Netrvalová, Marie; Savková, Jarmila; Novák, Petr; Očenášek, Jan; Šutta, Pavol [New Technologies Research Centre, University of West Bohemia, Plzeň 30614 (Czech Republic); Kováč, Jaroslav [Slovak University of Technology, Faculty of Electrical Engineering and Information Technology, Il’kovičova 3, 81219 Bratislava (Slovakia); Jayavel, R. [Centre for Nanoscience and Technology, Anna University, Chennai 600025 (India)


    Highlights: • Highly preferred oriented [0 0 1] thin film columnar structure in ZnO:Ni from RF sputtering. • XRD confirmed the preferred orientation of ZnO structure from the only observed (0 0 2) plane. • Variation of refractive indices and optical band gap by doping of Ni in ZnO were studied. • Surface morphology and mechanical properties of the thin films were studied by SEM and AFM. • Critical concentration of Ni for the rise and enhancement of ferromagnetism was studied by VSM. - Abstract: Nickel doped ZnO (ZnO:Ni) thin films are considered to be promising materials for optoelectronic applications. The doping of transition metal ion modifies the optical and physical properties of the materials. Therefore, studies on optical and physical properties are important for such applications. In the present work, the ZnO:Ni thin films with different Ni concentrations were deposited on Si (1 0 0) and corning glass substrates at 400 °C by reactive magnetron sputtering using Ar and O{sub 2} gas mixture. The (0 0 2) growth plane of the ZnO was identified from the X-ray diffraction experiment. It was also confirmed that the films exhibit strong preferred orientation (texture) of crystalline columns in the direction [0 0 1] perpendicular to the substrate surface. The optical transmittance, band gap, and refractive indices of the thin films were studied by UV–Vis spectroscopy, photoluminescence and spectroscopic ellipsometry. The optical band gap and refractive index of the thin films decreased with increase of Ni content. The Raman and FT-IR spectroscopic studies were used to explain the modes of vibrations of the functional groups in the material. The surface topography, grain size, distribution, and fine structure of the thin films were analyzed by using scanning electron microscopy (SEM) and atomic force microscopy (AFM). The hardness of the films was measured using a nanoindenter coupled with AFM. The growth of ferromagnetism by the effect of Ni content was

  4. Numerical study of capacitive coupled HBr/Cl2 plasma discharge for dry etch applications (United States)

    Gul, Banat; Ahmad, Iftikhar; Zia, Gulfam; Aman-ur-Rehman


    HBr/Cl2 plasma discharge is investigated to study the etchant chemistry of this discharge by using the self-consistent fluid model. A comprehensive set of gas phase reactions (83 reactions) including primary processes such as excitation, dissociation, and ionization are considered in the model along with 24 species. Our findings illustrate that the densities of neutral species (i.e., Br, HCl, Cl, H, and H2) produced in the reactor are higher than charged species (i.e., Cl2+, Cl-, HBr+, and Cl+). Density profile of neutral and charged species followed bell shaped and double humped distributions, respectively. Increasing Cl2 fraction in the feedback gases (HBr/Cl2 from 90/10 to 10/90) promoted the production of Cl, Cl+, and Cl2+ in the plasma, indicating that chemical etching pathway may be preferred at high Cl-environment. These findings pave the way towards controlling/optimizing the Si-etching process.

  5. Investigational study of optical function materials for two-dimensional data processing; Nijigen joho shoriyo hikari kino zairyo ni kansuru chosa kenkyu

    Energy Technology Data Exchange (ETDEWEB)



    The paper investigated/studied `space light modulation materials,` `dynamic hologram/memory materials,` `optical waveguide path materials,` etc. which become key materials in the high speed two dimensional processing. As to electrooptical materials proposed in this investigational study, the external electric field and the electric charges generated make quality of molecules themselves directly change to memory strong/weak signals of light. Therefore, the response velocity becomes less than a millionth of that of the liquid crystal display, and high speed which is needed for realtime moving image processing is anticipated. Hologram includes the phase information in addition to information on light strength. Therefore, it is a large capacity record medium and at the same time a record medium which can read/write two dimensional information as it is. With optical fiber, images cannot be transmitted as they are. Light waveguide path materials are those that accumulate roles of mirror and lens in a sheet of the material and construct a system which is strong in vibration, as optical parts connecting among materials for two dimensional data processing. 273 refs., 107 figs., 17 tabs.

  6. Investigation on structural, optical, thermal, mechanical and dielectric properties of L-proline cadmium chloride monohydrate single crystals: An efficient NLO material

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Preeti; Hasmuddin, Mohd [Crystal Growth and XRD Lab, Department of Physics, Jamia Millia Islamia, New Delhi 110 025 (India); Shakir, Mohd [Crystal Growth and XRD Lab, Department of Physics, Jamia Millia Islamia, New Delhi 110 025 (India); CSIR-National Physical Laboratory, New Delhi 110 012 (India); Department of Physics, ARSD College, University of Delhi, New Delhi 110021 (India); Vijayan, N. [Department of Physics, Kakatiya University, Warangal 506 009 (India); Abdullah, M.M. [Crystal Growth and XRD Lab, Department of Physics, Jamia Millia Islamia, New Delhi 110 025 (India); Advanced Materials and Nano-research Centre (AMNC), Faculty of Science and Arts, Najran University, P.O. Box-1988, Najran 11001 (Saudi Arabia); Ganesh, V. [Department of Physics, Kakatiya University, Warangal 506 009 (India); Wahab, M.A., E-mail: [Crystal Growth and XRD Lab, Department of Physics, Jamia Millia Islamia, New Delhi 110 025 (India)


    In the present work, we have grown single crystals of L-proline cadmium chloride monohydrate (LPCCM) by slow evaporation solution technique (SEST) at room temperature and recorded their live growth kinetics with the help of inverted microscope. Crystal size at various stages of growth and its corresponding morphology was also recorded. Powder X-ray diffraction (PXRD) analysis of LPCCM single crystals confirmed the orthorhombic structure. Respective values of crystallite size, strain and dislocation density have been calculated using PXRD data. Metal complex coordination of the single crystal is studied by FTIR spectroscopic. The optical properties of the grown crystals were investigated through UV–VIS spectroscopic studies and shows that the crystals have very low absorption in entire characterized wavelength range 200–800 nm. The optical band gap was calculated and found to be ∼5.6 eV. Optical constants of the material is determined by theoretical calculations. The chemical etching study was also carried out to study the density of defects in the grown crystals. The photoluminous excitation and emission spectra and thermal property by TGA/DTA curve were recorded. Further, the mechanical properties have been studied using Vicker's microhardness tester as well as many parameters such as fracture toughness (K{sub c}), Brittleness index (B{sub i}) and yield strength (σ{sub ν}) are presented. Dielectric studies have been carried out with varying frequency and temperatures. - Highlights: • The morphology of LPCCM crystal was observed during growth under inverted microscope. • Observation also shows defects also grows with the growth of crystal. • Positive temperature coefficient is observed. • The optical study shows its suitability for photonics and optical applications.

  7. An experimental investigation on the slow strain rate corrosion of 316L stainless steel containing H2S and Cl-%316L钢在含H2S、Cl-水溶液中的慢应变速率腐蚀试验研究

    Institute of Scientific and Technical Information of China (English)

    董绍平; 袁军国; 方德明; 高增梁; 张庆; 刘富胜


    通过慢应变速率法(SSRT)应力腐蚀试验,得到了316L钢的应力腐蚀敏感性指数,回归出计算应力腐蚀敏感性指数的方程,表明水溶液中Cl-对316L钢的应力腐蚀影响较大,而H2S的影响小。%Through the stress corrosion test of slow strain rate test, the sensitive indexes of the stress corrosion of 316L stainless steel was derived, the regression equation was given for calculating the sensitive indexes of stress corrosion of 316L stainless steel. It shows that the influence of Cl- in solution on the stress corrosion of 316L stsinless steel was some strong and the influence of H2S in solution on the stress corrosion of 316L stainless steel was small.

  8. Donor–Acceptor Copolymers of Relevance for Organic Photovoltaics: A Theoretical Investigation of the Impact of Chemical Structure Modifications on the Electronic and Optical Properties

    KAUST Repository

    Pandey, Laxman


    We systematically investigate at the density functional theory level how changes to the chemical structure of donor-acceptor copolymers used in a number of organic electronics applications influences the intrinsic geometric, electronic, and optical properties. We consider the combination of two distinct donors, where a central five-membered ring is fused on both sides by either a thiophene or a benzene ring, with 12 different acceptors linked to the donor either directly or through thienyl linkages. The interplay between the electron richness/deficiency of the subunits as well as the evolution of the frontier electronic levels of the isolated donors/acceptors plays a significant role in determining the electronic and optical properties of the copolymers. © 2012 American Chemical Society.

  9. Structural, optical and non-linear investigation of Eu3+: Al(NO$_3)_3$–SiO2 sol–gel glass

    Indian Academy of Sciences (India)

    S Hazarika; S Rai


    Optical absorption and fluorescence spectra of Eu3+ ions in Al(NO$_3)_3$–SiO2 sol–gel glass have been investigated using the Judd–Ofelt theory. JO intensity parameters () and subsequent radiative properties for ${}^{5}D_{0} \\rightarrow {}^{7}F_{1,2,4,6}$ transitions are determined. The lifetime (r) of ${}^{5}D_{0}$ state is computed and along with JO parameters are compared with their corresponding values in other glasses prepared by conventional technique. A structural analysis, using IR and XRD spectra and non-linear parametrization of the silica gel glass is carried out. The study reveals the glass to be a very good third order non-linear amorphous optical material.

  10. Electronic structure and magnetic and optical properties of double perovskite Bi2FeCrO6 from first-principles investigation

    Institute of Scientific and Technical Information of China (English)

    Song Zhe-Wen; Liu Bang-Gui


    Double perovskite Bi2FeCrO6,related with multiferroic BiFeO3,is very interesting because of its strong ferroelectricity and high magnetic Curie temperature beyond room temperature.We investigate its electronic structure and magnetic and optical properties by using a full-potential density-functional method.Our optimization shows that it is a robust ferrimagnetic semiconductor.This nonmetallic phase is formed due to crystal field splitting and spin exchange splitting,in contrast to previous studies.Spin exchange constants and optical properties are calculated.Our Monte Carlo magnetic Curie temperature is 450 K,much higher than any previously calculated value and consistent with experimental results.Our study and analysis reveal that the main magnetic mechanism is an antiferromagnetic superexchange between Fe and Cr over the intermediate O atom.These results are useful in understanding such perovskite materials and exploring their potential applications.

  11. Cl- channels in apoptosis

    DEFF Research Database (Denmark)

    Wanitchakool, Podchanart; Ousingsawat, Jiraporn; Sirianant, Lalida


    , and cystic fibrosis transmembrane conductance regulator (CFTR) in cellular apoptosis. LRRC8A-E has been identified as a volume-regulated anion channel expressed in many cell types. It was shown to be required for regulatory and apoptotic volume decrease (RVD, AVD) in cultured cell lines. Its presence also......(-) channels or as regulators of other apoptotic Cl(-) channels, such as LRRC8. CFTR has been known for its proapoptotic effects for some time, and this effect may be based on glutathione release from the cell and increase in cytosolic reactive oxygen species (ROS). Although we find that CFTR is activated...... by cell swelling, it is possible that CFTR serves RVD/AVD through accumulation of ROS and activation of independent membrane channels such as ANO6. Thus activation of ANO6 will support cell shrinkage and induce additional apoptotic events, such as membrane phospholipid scrambling....

  12. ZnO:Mo:In nanofilms on SiO2 substrate under investigation framework of the second optical transition (United States)

    Souissi, A.; Amlouk, M.; Guermazi, S.


    ZnO and ZnO:Mo:In nanofilms were deposited on SiO2 substrate at 460 °C by the spray pyrolysis method with the molar ratio (Mo/Zn) set at 1% and (In/Zn) dosed at 1%, 2%, 3% and 10%. The optical, dielectric and photonic characteristics of these samples were analyzed from the optical spectra of transmission and reflection, which revealed the presence of two absorption edges. The first one was related to the ZnO:Mo:In typical transition and the second edge originated from the ZnO:Mo:In/SiO2 interface transition by the probable formation of an ultrafine layer identified as SiOx and/or ZnO(1-x)SiO2(x). The optical gap and Urbach energies of ZnO:Mo:In nanofilms varied almost uniformly and in a complementary manner depending on the co-doping of ∼3.28-3.24 eV and ∼82-136 meV. These energies associated with the interface varied randomly from 3.93 to 4.18 eV and ∼263 to 408 meV, and showed strong dependencies with the structural, crystalline and vibrational properties previously studied. They also displayed possible correlations with electron scattering time and the dc photoconductivity which reaches high value for film prepared using In = 2%. AFM study showed variable morphologies of the surfaces that are responsive to codoping elements, therefore at the interface, wherein the film growth began. All these factors influenced the results described above. The study also showed good agreement between rms roughness and TC texture coefficient of the studied films, of high transparency ∼89-92%. The films prepared with In = 2% revealed a high photoconductivity and could be used in photocatalytic and photonic applications.

  13. Investigation of structural, electronic, elastic and optical properties of Cd1-x-yZnxHgyTe alloys

    Directory of Open Access Journals (Sweden)

    M. Tamer


    Full Text Available Structural, optical and electronic properties and elastic constants of Cd1-x-yZnx HgyTe alloys have been studied by employing the commercial code Castep based on density functional theory. The generalized gradient approximation and local density approximation were utilized as exchange correlation. Using elastic constants for compounds, bulk modulus, band gap, Fermi energy and Kramers–Kronig relations, dielectric constants and the refractive index have been found through calculations. Apart from these, X-ray measurements revealed elastic constants and Vegard’s law. It is seen that results obtained from theory and experiments are all in agreement.

  14. Investigation of structural, electronic, elastic and optical properties of Cd1-x-yZnxHgyTe alloys (United States)

    Tamer, M.


    Structural, optical and electronic properties and elastic constants of Cd1-x-yZnx HgyTe alloys have been studied by employing the commercial code Castep based on density functional theory. The generalized gradient approximation and local density approximation were utilized as exchange correlation. Using elastic constants for compounds, bulk modulus, band gap, Fermi energy and Kramers-Kronig relations, dielectric constants and the refractive index have been found through calculations. Apart from these, X-ray measurements revealed elastic constants and Vegard's law. It is seen that results obtained from theory and experiments are all in agreement.

  15. Optical investigation of the one-dimensional confinement effects in narrow GaAs/GaAlAs quantum wires (United States)

    Birotheau, L.; Izrael, A.; Marzin, J. Y.; Azoulay, R.; Thierry-Mieg, V.; Ladan, F. R.


    We show optical data obtained at 8 K on narrow GaAs/GaAlAs quantum wires, with width down to 15 nm, fabricated by reactive ion etching and metal organic chemical vapor deposition overgrowth. Lateral confinement energies (up to 23 meV) and polarization effects are evidenced in the photoluminescence excitation spectra. These experimental results are in good agreement with calculated absorption spectra, which include the effects of wire width fluctuations, yielding, for our fabrication technique, a value of ±5 nm for these size fluctuations.

  16. CL2QCD - Lattice QCD based on OpenCL

    CERN Document Server

    Philipsen, Owe; Sciarra, Alessandro; Bach, Matthias


    We present the Lattice QCD application CL2QCD, which is based on OpenCL and can be utilized to run on Graphic Processing Units as well as on common CPUs. We focus on implementation details as well as performance results of selected features. CL2QCD has been successfully applied in LQCD studies at finite temperature and density and is available at

  17. Investigation on cytoskeleton dynamics for no-adherent cells subjected to point-like stimuli by digital holographic microscopy and holographic optical trapping (United States)

    Miccio, Lisa; Merola, Francesco; Memmolo, Pasquale; Mugnano, Martina; Fusco, Sabato; Netti, Paolo A.; Ferraro, Pietro


    Guiding, controlling and studying cellular functions are challenging themes in the biomedical field, as they are fundamental prerequisites for new therapeutic strategies from tissue regeneration to controlled drug delivery. In recent years, multidisciplinary studies in nanotechnology offer new tools to investigate important biophysical phenomena in response to the local physical characteristics of the extracellular environment, some examples are the mechanisms of cell adhesion, migration, communication and differentiation. Indeed for reproducing the features of the extracellular matrix in vitro, it is essential to develop active devices that evoke as much as possible the natural cellular environment. Our investigation is in the framework of studying and clarifying the biophysical mechanisms of the interaction between cells and the microenvironment in which they exist. We implement an optical tweezers setup to investigate cell material interaction and we use Digital Holography as non-invasive imaging technique in microscopy. We exploit Holographic Optical Tweezers arrangement in order to trap and manage functionalized micrometric latex beads to induce mechanical deformation in suspended cells. A lot of papers in literature examine the dynamics of the cytoskeleton when cells adhere on substrates and nowadays well established cell models are based on such research activities. Actually, the natural cell environment is made of a complex extracellular matrix and the single cell behavior is due to intricate interactions with the environment and are strongly correlated to the cell-cell interactions. Our investigation is devoted to understand the inner cell mechanism when it is mechanically stressed by point-like stimulus without the substrate influence.

  18. Preparation and investigation of optical, structural, and morphological properties of nanostructured ZnO:Mn thin films

    Indian Academy of Sciences (India)

    E Amoupour; F E Ghodsi; H Andarva; A Abdolahzadeh Ziabari


    Nanostructured ZnO:Mn thin films have been prepared by sol–gel dip coating method. The content of Mn in the sol was varied from 0 to 12 wt%. The effect of Mn concentration on the optical, structural, and morphological properties of ZnO thin films were studied by using Fourier transform infrared (FTIR), UV–visible and photoluminescence (PL) spectroscopy, X-ray diffraction (XRD) and scanning electron microscopy (SEM). XRD results showed that the films have hexagonal wurtzite structure at lower content of Mn. The diffraction peaks corresponding to ZnO disappeared and two diffraction peaks of MnO2 and Mn3O4 appeared at the highest value of doping concentration (viz., 12 wt\\%). SEM results revealed that the surface smoothness of the films improved at higher content of Mn. The optical band gap of the films decreased from 3.89 to 3.15 eV when the Mn concentration increased from 0 to 12 wt\\%. The PL spectra of the films showed the characteristic peaks linked to band-to-band, green and yellow emissions. Besides, the PL intensity of the samples decreased with increase in Mn concentration.

  19. Novel electronic ferroelectricity in an organic charge-order insulator investigated with terahertz-pump optical-probe spectroscopy (United States)

    Yamakawa, H.; Miyamoto, T.; Morimoto, T.; Yada, H.; Kinoshita, Y.; Sotome, M.; Kida, N.; Yamamoto, K.; Iwano, K.; Matsumoto, Y.; Watanabe, S.; Shimoi, Y.; Suda, M.; Yamamoto, H. M.; Mori, H.; Okamoto, H.


    In electronic-type ferroelectrics, where dipole moments produced by the variations of electron configurations are aligned, the polarization is expected to be rapidly controlled by electric fields. Such a feature can be used for high-speed electric-switching and memory devices. Electronic-type ferroelectrics include charge degrees of freedom, so that they are sometimes conductive, complicating dielectric measurements. This makes difficult the exploration of electronic-type ferroelectrics and the understanding of their ferroelectric nature. Here, we show unambiguous evidence for electronic ferroelectricity in the charge-order (CO) phase of a prototypical ET-based molecular compound, α-(ET)2I3 (ET:bis(ethylenedithio)tetrathiafulvalene), using a terahertz pulse as an external electric field. Terahertz-pump second-harmonic-generation(SHG)-probe and optical-reflectivity-probe spectroscopy reveal that the ferroelectric polarization originates from intermolecular charge transfers and is inclined 27° from the horizontal CO stripe. These features are qualitatively reproduced by the density-functional-theory calculation. After sub-picosecond polarization modulation by terahertz fields, prominent oscillations appear in the reflectivity but not in the SHG-probe results, suggesting that the CO is coupled with molecular displacements, while the ferroelectricity is electronic in nature. The results presented here demonstrate that terahertz-pump optical-probe spectroscopy is a powerful tool not only for rapidly controlling polarizations, but also for clarifying the mechanisms of ferroelectricity.

  20. Optical discovery and multiwavelength investigation of supernova remnant MCSNR J0512-6707 in the Large Magellanic Cloud

    CERN Document Server

    Reid, Warren A; Bozzetto, Luke M; Parker, Quentin A; Filipovic, Miroslav D


    We present optical, radio and X-ray data that confirm a new supernova remnant (SNR) in the Large Magellanic Cloud (LMC) discovered using our deep H-alpha imagery. Optically, the new SNR has a somewhat filamentary morphology and a diameter of 56 x 64 arcsec (13.5 x 15.5 pc at the 49.9 kpc distance of the LMC). Spectroscopic follow-up of multiple regions show high [SII]/H-alpha emission-line ratios ranging from 0.66+/-0.02 to 0.93+/-0.01, all of which are typical of an SNR. We found radio counterparts for this object using our new Australia Telescope Compact Array (ATCA) 6cm pointed observations as well as a number of available radio surveys at 8 640 MHz, 4 850 MHz, 1 377 MHz and 843 MHz. With these combined data we provide a spectral index (alpha) = -0.5 between 843 and 8640 MHz. Both spectral line analysis and the magnetic field strength, ranging from 124 - 184 mG, suggest a dynamical age between 2,200 and 4,700 yrs. The SNR has a previously catalogued X-ray counterpart listed as HP 483 in the ROSAT Position ...