WorldWideScience

Sample records for halide photographic film

  1. Personnel photographic film dosimetry

    International Nuclear Information System (INIS)

    Keirim-Markus, I.B.

    1981-01-01

    Technology of personnel photographic film dosimetry (PPD) based on the photographic effect of ionizing radiation is described briefly. Kinds of roentgen films used in PPD method are enumerated, compositions of a developer and fixing agents for these films are given [ru

  2. Effect of avalanche-type barrier discharge on a silver halide photographic material in the case of blocked ionic conductivity

    International Nuclear Information System (INIS)

    Boychenko, A. P.

    2012-01-01

    Imaging of avalanche-type barrier gas discharge excited by single videopulses ∼7 μs long is studied via chemical activation of an ion subsystem of microcrystals of silver halide photographic emulsions by 1-phenyl-5-mercaptotetrazole. Using “Retina” commercial X-ray film and specially fabricated photoemulsion microcrystals with effective surface and deep electron traps as an example, the selective gas-discharge sensitivity of photographic layers to applied-voltage polarity is detected. It is shown that their sensitivity to barrier discharge ignited by negative-polarity pulses (on the electrode with a photographic material) is higher than in the case of positive pulses, irrespective of the photographic material’s position in the capacitor system.

  3. Silver halide photographic material providing an image and an unsharp mask

    International Nuclear Information System (INIS)

    Broadhead, P.; Farnell, G.C.

    1981-01-01

    Desirable edge effects are produced by normal imagewise exposure and processing of a sensitive radiographic film comprising a transparent film support bearing a layer of a direct-positive silver halide emulsion and a layer of a negative silver halide emulsion and wherein the film comprises means to reduce crossover between the two emulsion layers, one of said emulsion layers being adapted to record a primary image and the other being adapted to record an unsharp mask image. (author)

  4. New ISO standard - personnel photographic film dosemeters

    International Nuclear Information System (INIS)

    Brabec, D.

    1980-01-01

    The ISO Standard 1757 ''Personnel Photographic Film Dosemeters'', issued in June 1980, is briefly described. UVVVR's own dosemeter developed for use in the national film dosimetry service in Czechoslovakia is evaluated in relation to this ISO Standard. (author)

  5. Solar cells, structures including organometallic halide perovskite monocrystalline films, and methods of preparation thereof

    KAUST Repository

    Bakr, Osman; Peng, Wei; Wang, Lingfei

    2017-01-01

    Embodiments of the present disclosure provide for solar cells including an organometallic halide perovskite monocrystalline film (see fig. 1.1B), other devices including the organometallic halide perovskite monocrystalline film, methods of making

  6. Solar cells, structures including organometallic halide perovskite monocrystalline films, and methods of preparation thereof

    KAUST Repository

    Bakr, Osman M.

    2017-03-02

    Embodiments of the present disclosure provide for solar cells including an organometallic halide perovskite monocrystalline film (see fig. 1.1B), other devices including the organometallic halide perovskite monocrystalline film, methods of making organometallic halide perovskite monocrystalline film, and the like.

  7. An objective protocol for comparing the noise performance of silver halide film and digital sensor

    Science.gov (United States)

    Cao, Frédéric; Guichard, Frédéric; Hornung, Hervé; Tessière, Régis

    2012-01-01

    Digital sensors have obviously invaded the photography mass market. However, some photographers with very high expectancy still use silver halide film. Are they only nostalgic reluctant to technology or is there more than meets the eye? The answer is not so easy if we remark that, at the end of the golden age, films were actually scanned before development. Nowadays film users have adopted digital technology and scan their film to take advantage from digital processing afterwards. Therefore, it is legitimate to evaluate silver halide film "with a digital eye", with the assumption that processing can be applied as for a digital camera. The article will describe in details the operations we need to consider the film as a RAW digital sensor. In particular, we have to account for the film characteristic curve, the autocorrelation of the noise (related to film grain) and the sampling of the digital sensor (related to Bayer filter array). We also describe the protocol that was set, from shooting to scanning. We then present and interpret the results of sensor response, signal to noise ratio and dynamic range.

  8. Phase recording for formation of holographic optical elements on silver-halide photographic emulsions

    Science.gov (United States)

    Ganzherli, Nina M.; Gulyaev, Sergey N.; Maurer, Irina A.; Chernykh, Dmitrii F.

    2009-05-01

    Holographic fabrication methods of regular and nonregular relief-phase structures on silver-halide photographic emulsions are considered. Methods of gelatin photodestruction under short-wave ultra-violet radiation and chemical hardening with the help of dichromated solutions were used as a technique for surface relief formation. The developed techniques permitted us to study specimens of holographic diffusers and microlens rasters with small absorption and high light efficiency.

  9. Miscellaneous Lasing Actions in Organo-Lead Halide Perovskite Films.

    Science.gov (United States)

    Duan, Zonghui; Wang, Shuai; Yi, Ningbo; Gu, Zhiyuan; Gao, Yisheng; Song, Qinghai; Xiao, Shumin

    2017-06-21

    Lasing actions in organo-lead halide perovskite films have been heavily studied in the past few years. However, due to the disordered nature of synthesized perovskite films, the lasing actions are usually understood as random lasers that are formed by multiple scattering. Herein, we demonstrate the miscellaneous lasing actions in organo-lead halide perovskite films. In addition to the random lasers, we show that a single or a few perovskite microparticles can generate laser emissions with their internal resonances instead of multiple scattering among them. We experimentally observed and numerically confirmed whispering gallery (WG)-like microlasers in polygon shaped and other deformed microparticles. Meanwhile, owing to the nature of total internal reflection and the novel shape of the nanoparticle, the size of the perovskite WG laser can be significantly decreased to a few hundred nanometers. Thus, wavelength-scale lead halide perovskite lasers were realized for the first time. All of these laser behaviors are complementary to typical random lasers in perovskite film and will help the understanding of lasing actions in complex lead halide perovskite systems.

  10. Non-hydrolytic metal oxide films for perovskite halide overcoating and stabilization

    Science.gov (United States)

    Martinson, Alex B.; Kim, In Soo

    2017-09-26

    A method of protecting a perovskite halide film from moisture and temperature includes positioning the perovskite halide film in a chamber. The chamber is maintained at a temperature of less than 200 degrees Celsius. An organo-metal compound is inserted into the chamber. A non-hydrolytic oxygen source is subsequently inserted into the chamber. The inserting of the organo-metal compound and subsequent inserting of the non-hydrolytic oxygen source into the chamber is repeated for a predetermined number of cycles. The non-hydrolytic oxygen source and the organo-metal compound interact in the chamber to deposit a non-hydrolytic metal oxide film on perovskite halide film. The non-hydrolytic metal oxide film protects the perovskite halide film from relative humidity of greater than 35% and a temperature of greater than 150 degrees Celsius, respectively.

  11. Emission Enhancement and Intermittency in Polycrystalline Organolead Halide Perovskite Films

    Directory of Open Access Journals (Sweden)

    Cheng Li

    2016-08-01

    Full Text Available Inorganic-organic halide organometal perovskites have demonstrated very promising performance for opto-electronic applications, such as solar cells, light-emitting diodes, lasers, single-photon sources, etc. However, the little knowledge on the underlying photophysics, especially on a microscopic scale, hampers the further improvement of devices based on this material. In this communication, correlated conventional photoluminescence (PL characterization and wide-field PL imaging as a function of time are employed to investigate the spatially- and temporally-resolved PL in CH3NH3PbI3−xClx perovskite films. Along with a continuous increase of the PL intensity during light soaking, we also observe PL blinking or PL intermittency behavior in individual grains of these films. Combined with significant suppression of PL blinking in perovskite films coated with a phenyl-C61-butyric acid methyl ester (PCBM layer, it suggests that this PL intermittency is attributed to Auger recombination induced by photoionized defects/traps or mobile ions within grains. These defects/traps are detrimental for light conversion and can be effectively passivated by the PCBM layer. This finding paves the way to provide a guideline on the further improvement of perovskite opto-electronic devices.

  12. Photographic materials

    International Nuclear Information System (INIS)

    1980-01-01

    Radiographic films based on silver halides are normally handled under red or orange safelights to prevent fogging due to their sensitivity to white light. The present invention relates to ultraviolet radiation sensitive material which can be handled under virtually white light without significant fogging. A photographic, chemically sensitised silver halide emulsion is described, containing 50-100 mole % of silver chloride, the higher the silver chloride content, the lower the visible light sensitivity. The remaining silver halide, if any, is silver bromide and/or silver iodide. The silver halide grains are grown in the presence of ammonia, an excess of chloride ions and tetraazaindene growth controller. Examples illustrating the invention are given. (U.K.)

  13. The importance of moisture in hybrid lead halide perovskite thin film fabrication

    NARCIS (Netherlands)

    Eperon, G.E.; Habisreutinger, S.N.; Leijtens, T.; Bruijnaers, B.J.; van Franeker, J.J.; deQuilettes, D.W.; Pathak, S.; Sutton, R.J.; Grancini, G.; Ginger, D.S.; Janssen, R.A.J.; Petrozza, A.; Snaith, H.J.

    2015-01-01

    Moisture, in the form of ambient humidity, has a significant impact on methylammonium lead halide perovskite films. In particular, due to the hygroscopic nature of the methylammonium component, moisture plays a significant role during film formation. This issue has so far not been well understood

  14. Ultrafast time-resolved spectroscopy of lead halide perovskite films

    Science.gov (United States)

    Idowu, Mopelola A.; Yau, Sung H.; Varnavski, Oleg; Goodson, Theodore

    2015-09-01

    Recently, lead halide perovskites which are organic-inorganic hybrid structures, have been discovered to be highly efficient as light absorbers. Herein, we show the investigation of the excited state dynamics and emission properties of non-stoichiometric precursor formed lead halide perovskites grown by interdiffusion method using steady-state and time-resolved spectroscopic measurements. The influence of the different ratios of the non-stoichiometric precursor solution was examined. The observed photoluminescence properties were correlated with the femtosecond transient absorption measurements.

  15. Metal Halide Perovskite Polycrystalline Films Exhibiting Properties of Single Crystals

    NARCIS (Netherlands)

    Brenes, Roberto; Guo, D.; Osherov, Anna; Noel, Nakita K.; Eames, Christopher; Hutter, E.M.; Pathak, Sandeep K.; Niroui, Farnaz; Friend, Richard H.; Islam, M. Saiful; Snaith, Henry J.; Bulović, Vladimir; Savenije, T.J.; Stranks, Samuel D.

    2017-01-01

    Metal halide perovskites are generating enormous excitement for use in solar cells and light-emission applications, but devices still show substantial non-radiative losses. Here, we show that by combining light and atmospheric treatments, we can increase the internal luminescence quantum

  16. Effects of radiation on photographic film. A study

    International Nuclear Information System (INIS)

    Dutton, D.M.

    1971-01-01

    This study of the effects of radiation on photographic film is related to the Nevada Test Site's underground nuclear testing program, which has been active since implementation of the Limited Test Ban Treaty of 1963. Residual radioactivity, which has accidentally been released on several tests, adversely affects the photographic film used in test data acquisition. The report defines this problem in terms of radiation-caused image degradation, radiation/matter interactions, types of radiation released by accidental venting, and the photographic effects of gamma and x radiation. Techniques and experimental findings are documented that may be useful in recovering information from radiation-fogged film. Techniques discussed include processing methods, shielding, image enhancement techniques, and operational handling of potentially irradiated film. (U.S.)

  17. Plasmonic characterization of photo-induced silver nanoparticles extracted from silver halide based TEM film

    Energy Technology Data Exchange (ETDEWEB)

    Sudheer,, E-mail: sudheer@rrcat.gov.in; Tiwari, P.; Rai, V. N.; Srivastava, A. K. [Indus Synchrotrons Utilization Division, Raja Ramanna Centre for Advanced Technology Indore, Madhya Pradesh 452013 (India); Varshney, G. K. [Laser Bio-medical Applications & Instrumentation Division, Raja Ramanna Centre for Advanced Technology Indore, Madhya Pradesh 452013 (India)

    2016-05-23

    The plasmonic responses of silver nanoparticles extracted from silver halide based electron microscope film are investigated. Photo-reduction process is carried out to convert the silver halide grains into the metallic silver. The centrifuge technique is used for separating the silver nanoparticles from the residual solution. Morphological study performed by field emission scanning electron microscope (FESEM) shows that all the nanoparticles have an average diameter of ~120 nm with a high degree of mono dispersion in size. The localized surface plasmon resonance (LSPR) absorption peak at ~537 nm confirms the presence of large size silver nanoparticles.

  18. Photographic materials

    International Nuclear Information System (INIS)

    Jamieson, P.B.

    1980-01-01

    Radiographic films based on silver halides are normally handled under red or orange safelights to prevent fogging due to their sensitivity to white light. The present invention relates to ultraviolet radiation sensitive material which can be handled under virtually white light without significant fogging. The film material is comprised of a base having at least one layer of a photographic silver halide emulsion and a yellow filter dye screening the emulsion from visible radiation. The silver halide emulsion contains 50-100 mole % of silver chloride, the higher the silver chloride content, the lower the visible light sensitivity. The nature and properties of the yellow filter dye are described. When recording an X-ray image, the film is loaded into the camera under white safelight conditions from which light of wavelength shorter than 400 nm is excluded. The film is in contact with one or more phosphor screens capable when struck by X-rays of emitting ultraviolet radiation, the screens having a peak ultraviolet emission within the wavelength range of 250-380 nm. After X-ray exposure, the film is removed and developed. Two examples illustrating the invention are given. (U.K.)

  19. With Raised Hands: Film as fantasy within a photograph

    DEFF Research Database (Denmark)

    Kau, Edvin

    2011-01-01

    About the manner in which this short film provides a poetic, audiovisuel interpretation and an adaptation of the famous WWII photograph from the Warshaw Ghetto. How are the dynamic elements of cinematic style used to create the viewer's experience of fantasy and provide a paradoxical sense of hope?...

  20. In Situ Preparation of Metal Halide Perovskite Nanocrystal Thin Films for Improved Light-Emitting Devices.

    Science.gov (United States)

    Zhao, Lianfeng; Yeh, Yao-Wen; Tran, Nhu L; Wu, Fan; Xiao, Zhengguo; Kerner, Ross A; Lin, YunHui L; Scholes, Gregory D; Yao, Nan; Rand, Barry P

    2017-04-25

    Hybrid organic-inorganic halide perovskite semiconductors are attractive candidates for optoelectronic applications, such as photovoltaics, light-emitting diodes, and lasers. Perovskite nanocrystals are of particular interest, where electrons and holes can be confined spatially, promoting radiative recombination. However, nanocrystalline films based on traditional colloidal nanocrystal synthesis strategies suffer from the use of long insulating ligands, low colloidal nanocrystal concentration, and significant aggregation during film formation. Here, we demonstrate a facile method for preparing perovskite nanocrystal films in situ and that the electroluminescence of light-emitting devices can be enhanced up to 40-fold through this nanocrystal film formation strategy. Briefly, the method involves the use of bulky organoammonium halides as additives to confine crystal growth of perovskites during film formation, achieving CH 3 NH 3 PbI 3 and CH 3 NH 3 PbBr 3 perovskite nanocrystals with an average crystal size of 5.4 ± 0.8 nm and 6.4 ± 1.3 nm, respectively, as confirmed through transmission electron microscopy measurements. Additive-confined perovskite nanocrystals show significantly improved photoluminescence quantum yield and decay lifetime. Finally, we demonstrate highly efficient CH 3 NH 3 PbI 3 red/near-infrared LEDs and CH 3 NH 3 PbBr 3 green LEDs based on this strategy, achieving an external quantum efficiency of 7.9% and 7.0%, respectively, which represent a 40-fold and 23-fold improvement over control devices fabricated without the additives.

  1. The Importance of Moisture in Hybrid Lead Halide Perovskite Thin Film Fabrication.

    Science.gov (United States)

    Eperon, Giles E; Habisreutinger, Severin N; Leijtens, Tomas; Bruijnaers, Bardo J; van Franeker, Jacobus J; deQuilettes, Dane W; Pathak, Sandeep; Sutton, Rebecca J; Grancini, Giulia; Ginger, David S; Janssen, Rene A J; Petrozza, Annamaria; Snaith, Henry J

    2015-09-22

    Moisture, in the form of ambient humidity, has a significant impact on methylammonium lead halide perovskite films. In particular, due to the hygroscopic nature of the methylammonium component, moisture plays a significant role during film formation. This issue has so far not been well understood and neither has the impact of moisture on the physical properties of resultant films. Herein, we carry out a comprehensive and well-controlled study of the effect of moisture exposure on methylammonium lead halide perovskite film formation and properties. We find that films formed in higher humidity atmospheres have a less continuous morphology but significantly improved photoluminescence, and that film formation is faster. In photovoltaic devices, we find that exposure to moisture, either in the precursor solution or in the atmosphere during formation, results in significantly improved open-circuit voltages and hence overall device performance. We then find that by post-treating dry films with moisture exposure, we can enhance photovoltaic performance and photoluminescence in a similar way. The enhanced photoluminescence and open-circuit voltage imply that the material quality is improved in films that have been exposed to moisture. We determine that this improvement stems from a reduction in trap density in the films, which we postulate to be due to the partial solvation of the methylammonium component and "self-healing" of the perovskite lattice. This work highlights the importance of controlled moisture exposure when fabricating high-performance perovskite devices and provides guidelines for the optimum environment for fabrication. Moreover, we note that often an unintentional water exposure is likely responsible for the high performance of solar cells produced in some laboratories, whereas careful synthesis and fabrication in a dry environment will lead to lower-performing devices.

  2. Combinatorial screening of halide perovskite thin films and solar cells by mask-defined IR laser molecular beam epitaxy

    OpenAIRE

    Kawashima, Kazuhiro; Okamoto, Yuji; Annayev, Orazmuhammet; Toyokura, Nobuo; Takahashi, Ryota; Lippmaa, Mikk; Itaka, Kenji; Suzuki, Yoshikazu; Matsuki, Nobuyuki; Koinuma, Hideomi

    2017-01-01

    Abstract As an extension of combinatorial molecular layer epitaxy via ablation of perovskite oxides by a pulsed excimer laser, we have developed a laser molecular beam epitaxy (MBE) system for parallel integration of nano-scaled thin films of organic?inorganic hybrid materials. A pulsed infrared (IR) semiconductor laser was adopted for thermal evaporation of organic halide (A-site: CH3NH3I) and inorganic halide (B-site: PbI2) powder targets to deposit repeated A/B bilayer films where the thic...

  3. Reversal film development for streamer chamber track photographs

    International Nuclear Information System (INIS)

    Bahr, J.

    1982-01-01

    It is the aim of this work to create a method of photographic development specially adapted to streamer image recording, i.e., with high sensitivity, only two signal levels, low dependence of the track signal on image intensity having a great jitter and noise suppression. The method has to be suitable for machine development of high speed films. A reversal photographic development was used to realize these demands, whereby strong fogging in the first step negative development and a solving process for silver bromide after blackening are specially introduced process stages. This results in a step-function shaped characteristic curve with small transition region having only two signal levels, i. e., independence of streamer image density, good resolution, fine grain, suppression of flares and low noise in the signal of the clear streamer images

  4. Photographic film dosimetry for high-energy accelerator radiation

    International Nuclear Information System (INIS)

    Komochkov, M.M.; Salatskaya, M.I.

    1981-01-01

    A technique for personnel photographic film dosimetry (PPFDN) of wide energy spectrum neutrons intended for measuring the effect of accelerating device radiation on personnel is described. Procedures of data measurement and processing as well as corrections to hadron contribution are presented. It is noted that the PPFDN method permits to measure a neutron dose equivalent for personnel in the range from 0.01 to 0.02 up to 100 rem, if the relativistic neutron contribution to a total dose does not exceed 5%. The upper limit of the measured dose reduced several times for a greater contribution of relativistic neutrons to the total dose [ru

  5. Electrochemistry and Spectroelectrochemistry of Lead Halide Perovskite Films: Materials Science Aspects and Boundary Conditions.

    Science.gov (United States)

    Samu, Gergely F; Scheidt, Rebecca A; Kamat, Prashant V; Janáky, Csaba

    2018-02-13

    The unique optoelectronic properties of lead halide perovskites have triggered a new wave of excitement in materials chemistry during the past five years. Electrochemistry, spectroelectrochemistry, and photoelectrochemistry could be viable tools both for analyzing the optoelectronic features of these materials and for assembling them into hybrid architectures (e.g., solar cells). At the same time, the instability of these materials limits the pool of solvents and electrolytes that can be employed in such experiments. The focus of our study is to establish a stability window for electrochemical tests for all-inorganic CsPbBr 3 and hybrid organic-inorganic MAPbI 3 perovskites. In addition, we aimed to understand the reduction and oxidation events that occur and to assess the damage done during these processes at extreme electrochemical conditions. In this vein, we demonstrated the chemical, structural, and morphological changes of the films in both reductive and oxidative environments. Taking all these results together as a whole, we propose a set of boundary conditions and protocols for how electrochemical experiments with lead halide perovskites should be carried out and interpreted. The presented results will contribute to the understanding of the electrochemical response of these materials and lead to a standardization of results in the literature so that comparisons can more easily be made.

  6. Electrochemistry and Spectroelectrochemistry of Lead Halide Perovskite Films: Materials Science Aspects and Boundary Conditions

    KAUST Repository

    Samu, Gergely F.; Scheidt, Rebecca A; Kamat, Prashant V.; Janá ky, Csaba

    2017-01-01

    The unique optoelectronic properties of lead halide perovskites have triggered a new wave of excitement in materials chemistry during the past five years. Electrochemistry, spectroelectrochemistry, and photoelectrochemistry could be viable tools both for analyzing the optoelectronic features of these materials and to assemble their hybrid architectures (e.g., solar cells). At the same time, the instability of these materials limits the pool of solvents and electrolytes that can be employed in such experiments. The focus of our study is to establish a stability window for electrochemical tests for all-inorganic CsPbBr3 and hybrid organic-inorganic MaPbI3 perovskites. In addition, we aimed to understand the reduction and oxidation events that occur and to assess the damage done during these processes at extreme electrochemical conditions. In this vein, we demonstrated the chemical, structural, and morphological changes of the films in both reductive and oxidative environments. Taking all these results together as a whole, we propose a set of boundary conditions and protocols for how electrochemical experiments with lead halide perovskites should be carried out and interpreted. We believe that the presented results will contribute to the understanding of the electrochemical response of these materials and lead to a standardization of results in the literature so that easier comparisons can be made.

  7. Electrochemistry and Spectroelectrochemistry of Lead Halide Perovskite Films: Materials Science Aspects and Boundary Conditions

    KAUST Repository

    Samu, Gergely F.

    2017-12-06

    The unique optoelectronic properties of lead halide perovskites have triggered a new wave of excitement in materials chemistry during the past five years. Electrochemistry, spectroelectrochemistry, and photoelectrochemistry could be viable tools both for analyzing the optoelectronic features of these materials and to assemble their hybrid architectures (e.g., solar cells). At the same time, the instability of these materials limits the pool of solvents and electrolytes that can be employed in such experiments. The focus of our study is to establish a stability window for electrochemical tests for all-inorganic CsPbBr3 and hybrid organic-inorganic MaPbI3 perovskites. In addition, we aimed to understand the reduction and oxidation events that occur and to assess the damage done during these processes at extreme electrochemical conditions. In this vein, we demonstrated the chemical, structural, and morphological changes of the films in both reductive and oxidative environments. Taking all these results together as a whole, we propose a set of boundary conditions and protocols for how electrochemical experiments with lead halide perovskites should be carried out and interpreted. We believe that the presented results will contribute to the understanding of the electrochemical response of these materials and lead to a standardization of results in the literature so that easier comparisons can be made.

  8. Electrochemistry and Spectroelectrochemistry of Lead Halide Perovskite Films: Materials Science Aspects and Boundary Conditions

    Science.gov (United States)

    2017-01-01

    The unique optoelectronic properties of lead halide perovskites have triggered a new wave of excitement in materials chemistry during the past five years. Electrochemistry, spectroelectrochemistry, and photoelectrochemistry could be viable tools both for analyzing the optoelectronic features of these materials and for assembling them into hybrid architectures (e.g., solar cells). At the same time, the instability of these materials limits the pool of solvents and electrolytes that can be employed in such experiments. The focus of our study is to establish a stability window for electrochemical tests for all-inorganic CsPbBr3 and hybrid organic–inorganic MAPbI3 perovskites. In addition, we aimed to understand the reduction and oxidation events that occur and to assess the damage done during these processes at extreme electrochemical conditions. In this vein, we demonstrated the chemical, structural, and morphological changes of the films in both reductive and oxidative environments. Taking all these results together as a whole, we propose a set of boundary conditions and protocols for how electrochemical experiments with lead halide perovskites should be carried out and interpreted. The presented results will contribute to the understanding of the electrochemical response of these materials and lead to a standardization of results in the literature so that comparisons can more easily be made. PMID:29503507

  9. Junction Propagation in Organometal Halide Perovskite-Polymer Composite Thin Films.

    Science.gov (United States)

    Shan, Xin; Li, Junqiang; Chen, Mingming; Geske, Thomas; Bade, Sri Ganesh R; Yu, Zhibin

    2017-06-01

    With the emergence of organometal halide perovskite semiconductors, it has been discovered that a p-i-n junction can be formed in situ due to the migration of ionic species in the perovskite when a bias is applied. In this work, we investigated the junction formation dynamics in methylammonium lead tribromide (MAPbBr 3 )/polymer composite thin films. It was concluded that the p- and n- doped regions propagated into the intrinsic region with an increasing bias, leading to a reduced intrinsic perovskite layer thickness and the formation of an effective light-emitting junction regardless of perovskite layer thicknesses (300 nm to 30 μm). The junction propagation also played a major role in deteriorating the LED operation lifetime. Stable perovskite LEDs can be achieved by restricting the junction propagation after its formation.

  10. Formation of random and regular relief-phase structures on silver halide photographic emulsions by holographic methods

    Science.gov (United States)

    Ganzherli, N. M.; Gulyaev, S. N.; Gurin, A. S.; Kramushchenko, D. D.; Maurer, I. A.; Chernykh, D. F.

    2009-07-01

    The formation of diffusers and microlens rasters on silver halide emulsions by holographic methods is considered. Two techniques for converting amplitude holographic recording to relief-phase recording, selective curing and irradiation of the emulsion gelatin by short-wavelength UV radiation, are compared.

  11. Femtosecond time-resolved photodissociation dynamics of methyl halide molecules on ultrathin gold films

    Directory of Open Access Journals (Sweden)

    Mihai E. Vaida

    2011-09-01

    Full Text Available The photodissociation of small organic molecules, namely methyl iodide, methyl bromide, and methyl chloride, adsorbed on a metal surface was investigated in real time by means of femtosecond-laser pump–probe mass spectrometry. A weakly interacting gold surface was employed as substrate because the intact adsorption of the methyl halide molecules was desired prior to photoexcitation. The gold surface was prepared as an ultrathin film on Mo(100. The molecular adsorption behavior was characterized by coverage dependent temperature programmed desorption spectroscopy. Submonolayer preparations were irradiated with UV light of 266 nm wavelength and the subsequently emerging methyl fragments were probed by photoionization and mass spectrometric detection. A strong dependence of the excitation mechanism and the light-induced dynamics on the type of molecule was observed. Possible photoexcitation mechanisms included direct photoexcitation to the dissociative A-band of the methyl halide molecules as well as the attachment of surface-emitted electrons with transient negative ion formation and subsequent molecular fragmentation. Both reaction pathways were energetically possible in the case of methyl iodide, yet, no methyl fragments were observed. As a likely explanation, the rapid quenching of the excited states prior to fragmentation is proposed. This quenching mechanism could be prevented by modification of the gold surface through pre-adsorption of iodine atoms. In contrast, the A-band of methyl bromide was not energetically directly accessible through 266 nm excitation. Nevertheless, the one-photon-induced dissociation was observed in the case of methyl bromide. This was interpreted as being due to a considerable energetic down-shift of the electronic A-band states of methyl bromide by about 1.5 eV through interaction with the gold substrate. Finally, for methyl chloride no photofragmentation could be detected at all.

  12. The Latest Development of the Preparation of Silver Halide Photographic Emulsions%银盐照相乳剂制备最新动向

    Institute of Scientific and Technical Information of China (English)

    边国俊

    2001-01-01

    This article analyses the emulsion preparation patents of silverhalide photographic materials in American Chemical Abstracts,especially the patents applied by Eastman Kodak and Fuji companies in recent years,and comcludes that the patents mainly cover the preparation of AgCl-rich silver halide tabular grain emulsions,introduction of line dislocation to tabular grains and adding method of silver iodide.%通过分析《美国化学文摘》中关于银盐照相材料的乳剂制备专利,了解到近几年柯达、富士等公司申请的专利主要涉及富氯卤化银T-颗粒乳剂的制备、在T-颗粒上引入线性位错和碘化银补加方法。

  13. Comparison of film and digital fundus photographs in eyes of individuals with diabetes mellitus

    DEFF Research Database (Denmark)

    Gangaputra, Sapna; Almukhtar, Talat; Glassman, Adam R

    2011-01-01

    To compare grading of diabetic retinopathy (DR) and diabetic macular edema (DME) from stereoscopic film versus stereoscopic digital photographs obtained from a subset of Diabetic Retinopathy Clinical Research Network (DRCR.net) participants.......To compare grading of diabetic retinopathy (DR) and diabetic macular edema (DME) from stereoscopic film versus stereoscopic digital photographs obtained from a subset of Diabetic Retinopathy Clinical Research Network (DRCR.net) participants....

  14. Diffraction efficiency of plasmonic gratings fabricated by electron beam lithography using a silver halide film

    Energy Technology Data Exchange (ETDEWEB)

    Sudheer,, E-mail: sudheer@rrcat.gov.in, E-mail: sudheer.rrcat@gmail.com; Tiwari, P.; Srivastava, Himanshu; Rai, V. N.; Srivastava, A. K.; Naik, P. A. [Homi Bhabha National Institute, Mumbai, Maharashtra 400094 (India); Indus Synchrotrons Utilization Division, Raja Ramanna Centre for Advanced Technology, Indore, Madhya Pradesh 452013 (India); Porwal, S. [Solid State Lasers Division, Raja Ramanna Centre for Advanced Technology, Indore, Madhya Pradesh 452013 (India); Bhartiya, S. [Homi Bhabha National Institute, Mumbai, Maharashtra 400094 (India); Laser Materials Development and Device Division, Raja Ramanna Centre for Advanced Technology, Indore, Madhya Pradesh 452013 (India); Rao, B. T. [Homi Bhabha National Institute, Mumbai, Maharashtra 400094 (India); Laser Materials Processing Division, Raja Ramanna Centre for Advanced Technology, Indore, Madhya Pradesh 452013 (India); Sharma, T. K. [Homi Bhabha National Institute, Mumbai, Maharashtra 400094 (India); Solid State Lasers Division, Raja Ramanna Centre for Advanced Technology, Indore, Madhya Pradesh 452013 (India)

    2016-07-28

    The silver nanoparticle surface relief gratings of ∼10 μm period are fabricated using electron beam lithography on the silver halide film substrate. Morphological characterization of the gratings shows that the period, the shape, and the relief depth in the gratings are mainly dependent on the number of lines per frame, the spot size, and the accelerating voltage of electron beam raster in the SEM. Optical absorption of the silver nanoparticle gratings provides a broad localized surface plasmon resonance peak in the visible region, whereas the intensity of the peaks depends on the number density of silver nanoparticles in the gratings. The maximum efficiency of ∼7.2% for first order diffraction is observed for the grating fabricated at 15 keV. The efficiency is peaking at 560 nm with ∼380 nm bandwidth. The measured profiles of the diffraction efficiency for the gratings are found in close agreement with the Raman-Nath diffraction theory. This technique provides a simple and efficient method for the fabrication of plasmonic nanoparticle grating structures with high diffraction efficiency having broad wavelength tuning.

  15. Bromine substitution improves excited-state dynamics in mesoporous mixed halide perovskite films.

    Science.gov (United States)

    Talbert, Eric M; Zarick, Holly F; Boulesbaa, Abdelaziz; Soetan, Naiya; Puretzky, Alexander A; Geohegan, David B; Bardhan, Rizia

    2017-08-24

    In this study, ultrafast transient absorption spectroscopy (TAS) is utilized to examine the excited-state dynamics in methylammonium lead iodide/bromide (MAPb(I 1-x Br x ) 3 ) perovskites as a function of bromide content. TAS spectral behavior reveals characteristic lifetimes for thermalization, recombination, and charge carrier injection of MAPb(I 1-x Br x ) 3 from x = 0 to 0.3 infiltrated in mesoporous titania films. Carrier recombination and charge injection lifetimes demonstrated a discernable increase with Br content likely because high carrier populations are supported by the higher density of vacant electronic states in mixed-halide perovskites due to the increased capacity of the conduction band. However, we observe for the first time that carrier thermalization lifetimes significantly decrease with increasing Br. This suggests that the shift in crystal structure from tetragonal towards pseudocubic accelerates carrier cooling, resulting in the relief of the hot phonon bottleneck. Furthermore, the stabilized MAPb(I 1-x Br x ) 3 samples exhibit a lower Burstein-Moss shift of 0.07-0.08 eV compared to pure MAPbI 3 (0.12 eV). Our results provide evidence that Br inclusion contributes to a broadening of the parabolic conduction band and to improvement in electron-phonon coupling and phonon propagation in the lattice.

  16. High-Performance Red-Light Photodetector Based on Lead-Free Bismuth Halide Perovskite Film.

    Science.gov (United States)

    Tong, Xiao-Wei; Kong, Wei-Yu; Wang, You-Yi; Zhu, Jin-Miao; Luo, Lin-Bao; Wang, Zheng-Hua

    2017-06-07

    In this study, we developed a sensitive red-light photodetector (RLPD) based on CsBi 3 I 10 perovskite thin film. This inorganic, lead-free perovskite was fabricated by a simple spin-coating method. Device analysis reveals that the as-assembled RLPD was very sensitive to 650 nm light, with an on/off ratio as high as 10 5 . The responsivity and specific detectivity of the device were estimated to be 21.8 A/W and 1.93 × 10 13 Jones, respectively, which are much better than those of other lead halide perovskite devices. In addition, the device shows a fast response (rise time: 0.33 ms; fall time: 0.38 ms) and a high external quantum efficiency (4.13 × 10 3 %). It is also revealed that the RLPD has a very good device stability even after storage for 3 months under ambient conditions. In summary, we suggest that the CsBi 3 I 10 perovskite photodetector developed in this study may have potential applications in future optoelectronic systems.

  17. Luminescent unit computerization to research spectral characteristics of fine film alkali halide crystal

    International Nuclear Information System (INIS)

    Zhalimbetov, T.; Zhabetov, A.; Moldagaliev, A.; Sarmukhanov, E.; Shunkeev, K.; Shunkeev, S.; Abdullin, K.; Tokmoldin, C.

    2002-01-01

    The fundamental optical absorption of ion crystals characterizes the creation of different free low energetic electronic excitation (the excitons and electron-hole pairs), but their straight registration is not possible because of incommensurable big absorption factor of alkali halide monocrystals. So to registration the spectrums of alkali halide monocrystal very fine layers are necessary. We have received fine films of Nal and KCl in system of KCl-Nal-KCl, KCl-KI-KCl on the base of universal vacuum post VUP-4, VUP-5 by thermal evaporation. A unique spectral unit has been created For this on the basic the SDL-2 complex. Complex consists of radiator, systems of condensers, monochromators MDR-12 and MDR-23, receivers of radiation, controller by unit. Connect and control of monochromators by means of IBM-compatible computer has been created. Kinematics schemes of monochromators provide consequent removing on output slot of monochromatic radiation in operating range of each diffraction lattice and indication its wavelength. The tumbling diffraction lattices is done the crossbar engines SHDR-711. For this special plate of control and block of reinforcement for crossbar engines in monochromators MDR-12 and MDR-23 are designed and constructed. Created controller of monochromators consists of double cascade preamplifier on transistors n-p-n type (815G) and logical scheme, constructed on summers and K555 series triggers. The preamplifier is used for reinforcement of signal to available amplifier on transistors KT837D. The logical scheme reduces the number of used categories of bidirectional port and enables unhooking the feeding to the windings of crossbar engine at conservation of previous combination of signals. The connection controller of monochromators is done through controller of port of computer with use the parallel interface. For installing computerized system of collection and data processing is provided marketed by means of modern object-oriented programming

  18. Interface Engineering and Morphology Study of Thin Film Organic-Inorganic Halide Perovskite Optoelectronic Devices

    Science.gov (United States)

    Meng, Lei

    Solar energy harvesting through photovoltaic conversion has gained great attention as a sustainable and environmentally friendly solution to meet the rapidly increasing global energy demand. Currently, the high cost of solar-cell technology limits its widespread use. This situation has generated considerable interest in developing alternative solar-cell technologies that reduce cost through the use of less expensive materials and processes. Perovskite solar cells provide a promising low-cost technology for harnessing this energy source. In Chapter two, a moisture-assist method is introduced and studied to facilitate grain growth of solution processed perovskite films. As an approach to achieve high-quality perovskite films, I anneal the precursor film in a humid environment (ambient air) to dramatically increase grain size, carrier mobility, and charge carrier lifetime, thus improving electrical and optical properties and enhancing photovoltaic performance. It is revealed that mild moisture has a positive effect on perovskite film formation, demonstrating perovskite solar cells with 17.1% power conversion efficiency. Later on, in Chapter four, an ultrathin flexible device delivering a PCE of 14.0% is introduced. The device is based on silver-mesh substrates exhibiting superior durability against mechanical bending. Due to their low energy of formation, organic lead iodide perovskites are also susceptible to degradation in moisture and air. The charge transport layer therefore plays a key role in protecting the perovskite photoactive layer from exposure to such environments, thus achieving highly stable perovskite-based photovoltaic cells. Although incorporating organic charge transport layers can provide high efficiencies and reduced hysteresis, concerns remain regarding device stability and the cost of fabrication. In this work, perovskite solar cells that have all solution-processed metal oxide charge transport layers were demonstrated. Stability has been

  19. Multi-directional radiation detector using photographic film

    International Nuclear Information System (INIS)

    Junet, L K; Majid, Z A Abdul; Sapuan, A H; Sayed, I S; Pauzi, N F

    2014-01-01

    Ionising radiation has always been part of our surrounding and people are continuously exposed to it. Ionising radiation is harmful to human health, thus it is vital to monitor the radiation. To monitor radiation, there are three main points that should be observed cautiously, which are energy, quantity, and direction of the radiation sources. A three dimensional (3D) dosimeter is an example of a radiation detector that provide these three main points. This dosimeter is able to record the radiation dose distribution in 3D. Applying the concept of dose detection distribution, study has been done to design a multi-directional radiation detector of different filter thicknesses. This is obtained by designing a cylinder shaped aluminum filter with several layers of different thickness. Black and white photographic material is used as a radiation-sensitive material and a PVC material has been used as the enclosure. The device is then exposed to a radiation source with different exposure factors. For exposure factor 70 kVp, 16 mAs; the results have shown that optical density (OD) value at 135° is 1.86 higher compared with an OD value at 315° which is 0.71 as the 135° area received more radiation compare to 315° region. Furthermore, with an evidence of different angle of film give different value of OD shows that this device has a multidirectional ability. Materials used to develop this device are widely available in the market, thus reducing the cost of development and making it suitable for commercialisation

  20. A Study on Organic-Metal Halide Perovskite Film Morphology, Interfacial Layers, Tandem Applications, and Encapsulation

    Science.gov (United States)

    Fisher, Dallas A.

    Organic-metal halide perovskites have brought about a new wave of research in the photovoltaic community due to their ideally suited optical and electronic parameters. In less than a decade, perovskite solar cell performance has skyrocketed to unprecedented efficiencies with numerous reported methodologies. Perovskites face many challenges with high-quality film morphology, interfacial layers, and long-term stability. In this work, these active areas are explored through a combination of studies. First, the importance of perovskite film precursor ratios is explored with an in-depth study of carrier lifetime and solvent-grain effects. It was found that excess lead iodide precursor greatly improves the film morphology by reducing pinholes in the solar absorber. Dimethyl sulfoxide (DMSO) solvent was found to mend grains, as well as improve carrier lifetime and device performance, possibly by passivation of grain boundary traps. Second, applications of perovskite with tandem cells is investigated, with an emphasis for silicon devices. Perovskites can easily be integrated with silicon, which already has strong market presence. Additionally, both materials' bandgaps are ideally suited for maximum tandem efficiency. The silicon/perovskite tandem device structure necessitated the optimization of inverted (p-i-n) structure devices. PEDOT:PSS, copper oxide, and nickel oxide p-type layers were explored through a combination of photoluminescent, chemical reactivity, and solar simulation results. Results were hindered due to resistive ITO and rough silicon substrates, but tandem devices displayed Voc indicative of proper monolithic performance. Third, replacement of titanium dioxide n-type layer with iron oxide (Fe 2O3, common rust) was studied. Iron oxide experiences less ultraviolet instability than that of titanium dioxide under solar illumination. It was found that current density slightly decreased due to parasitic absorption from the rust, but that open circuit voltage

  1. Systematic processing of the external individual monitoring data obtained by photographic film and capacitor dosemeters

    International Nuclear Information System (INIS)

    Krueger, F.; Shtuk, D.

    1983-01-01

    Individual radiation load measurements have been carried out both with photographic film and capacitor type dosemeters (CD). Systematic statistics methods were applied for the obtained data processing. The CD data were shown to exceed those measured with the film dosemeters. Specific features of the CD application are revealed that should be taken into account in practice [ru

  2. Detection of coloured tracks of heavy ion particles using photographic colour film

    International Nuclear Information System (INIS)

    Kuge, K.; Yasuda, N.; Kumagai, H.; Nakazawa, K.; Kobayashi, T.; Aoki, N.; Hasegawa, A.

    2001-01-01

    A photographic colour film, which was exposed to heavy ions, reveals a coloured dye image of the ion tracks. Since the colour film consists of several layers and different colours appear on each layer, three-dimensional information on the tracks in the layers can be obtained by the colour image. Previously, we have reported the method for which the tracks in different colours represented differences of track depth and we also discussed the disadvantages of using commercial colour films. Here we present the procedure for a self-made photographic coating and the development formula which can overcome the disadvantages

  3. Automation of photographic film processing in industrial radiography

    International Nuclear Information System (INIS)

    Arzhenukhin, V.K.; Grachev, A.V.; Kuleshov, A.V.; Majorov, A.N.

    1973-01-01

    The automation of industrial radiographs photoprocessing is discussed. It pulses into the foreground the requirement to physicomechanical characteristics of films. The most widely used radiographic film sorts and photoprocessing conditions are presented. The values of permissible mechanical effect at film photoprocessing in dependence on temperature are established. The main technical parameters of the automatic unit for radiographic film photoprocessing have been presented

  4. Low-energy x-ray response of photographic films. Part I. Mathematical models

    International Nuclear Information System (INIS)

    Henke, B.L.; Kwok, S.L.; Uejio, J.Y.; Yamada, H.T.; Young, G.C.

    1984-01-01

    Relatively simple mathematical models are developed for optical density as a function of the x-ray intensity, its angle of incidence and photon energy in the 100 to 10,000 eV region for monolayer and emulsion types of photographic films. Semi-empirical relations have been applied to characterize a monolayer film, Kodak 101-07, and an emulsion type film, Kodak RAR 2497, which fit calibration data at nine photon energies well within typical experimental error

  5. Low-energy x-ray response of photographic films. I. Mathematical models

    International Nuclear Information System (INIS)

    Henke, B.L.; Kwok, S.L.; Uejio, J.Y.; Yamada, H.T.; Young, G.C.

    1984-01-01

    Relatively simple mathematical models are developed to determine the optical density as a function of the x-ray intensity, its angle of incidence, and its photon energy in the 100--10,000-eV region for monolayer and emulsion types of photographic films. Semiempirical relations are applied to characterize a monolayer film (Kodak 101-07) and an emilsion-type film (Kodak RAR 2497); these relations fit calibration data at nine photon energies well within typical experimental error

  6. Making and Breaking of Lead Halide Perovskites

    KAUST Repository

    Manser, Joseph S.; Saidaminov, Makhsud I.; Christians, Jeffrey A.; Bakr, Osman; Kamat, Prashant V.

    2016-01-01

    To date, improvements in perovskite solar cell efficiency have resulted primarily from better control over thin film morphology, manipulation of the stoichiometry and chemistry of lead halide and alkylammonium halide precursors, and the choice

  7. Trap-Free Hot Carrier Relaxation in Lead–Halide Perovskite Films

    KAUST Repository

    Bretschneider, Simon A.; Laquai, Fré dé ric; Bonn, Mischa

    2017-01-01

    Photovoltaic devices that employ lead-halide perovskites as photoactive materials exhibit power conversion efficiencies of 22%. One of the potential routes to go beyond the current efficiencies is to extract charge carriers that carry excess energy, that is, nonrelaxed or

  8. Trap-Free Hot Carrier Relaxation in Lead–Halide Perovskite Films

    KAUST Repository

    Bretschneider, Simon A.

    2017-05-08

    Photovoltaic devices that employ lead-halide perovskites as photoactive materials exhibit power conversion efficiencies of 22%. One of the potential routes to go beyond the current efficiencies is to extract charge carriers that carry excess energy, that is, nonrelaxed or

  9. Formation of radiation images using photographic color film

    International Nuclear Information System (INIS)

    Kuge, Ken'ichi; Kobayashi, Takaharu; Hasegawa, Akira; Yasuda, Nakahiro; Kumagai, Hiroshi

    2001-01-01

    A new method to reveal the three-dimensional information of nuclear tracks in a nuclear emulsion layer was developed by the use of color photography. The tracks were represented with a color image in which different depths were indicated by different colors, and the three-dimensional information was obtained from color changes. We present the procedure for a self-made photographic coating and the development formula that can represent the color tracks clearly. (author)

  10. Energy - 1986/87 photographic film and video tape directory

    International Nuclear Information System (INIS)

    1988-01-01

    The directory is addressed to power supply companies wishing to convey audiovisual information to the power consumer. With emphasis on electric power supplies the films and videos complied are also touching upon other topical subjects. The directory aims at informing about the films and videos available on different subjects as well as about the best sources of supply. The audiovisual media selected are classified by: General aspects, energy sources, energy conversion, electric power distribution, electric power uses, engineering, miscellaneous. (orig./HP) [de

  11. Use of photographic film to estimate exposure near the Three Mile Island Nuclear Power Station

    International Nuclear Information System (INIS)

    Shuping, R.E.

    1981-02-01

    This report documents the methodology and results of a Bureau of Radiological Health study of the use of photographic film samples for estimating exposure levels near the Three Mile Island nuclear power station. The study was conducted to provide an independent assessment of the radiation levels near TMI following the accident on March 28, 1979

  12. Uniform sources of ionizing radiation of extended area from radiotoned photographic film

    International Nuclear Information System (INIS)

    Thackray, M.

    1978-01-01

    The technique of toning photographic films, that have been uniformly exposed and developed, with radionuclides to provide uniform sources of ionizing radiation of extended area and their uses in radiography are discussed. The suitability of various radionuclides for uniform-plane sources is considered. (U.K.)

  13. Prior Exposure to Creatures from a Horror Film: Live versus Photographic Representations.

    Science.gov (United States)

    Weiss, Audrey J.; And Others

    1993-01-01

    Finds that exposure to graphic photographs of worms taken from a horror film increased children's enjoyment of the horror movie segment and reduced fear reactions to the scene. Shows that exposure to a live earthworm was effective in reducing fear reactions to the movie only among boys but did alter children's affective reactions to and judgments…

  14. Behaviour of zirconium oxidation and is oxide films in alkali halide solutions as studied by electrochemical techniques

    International Nuclear Information System (INIS)

    Saleh, H.E.M.

    1996-01-01

    Study of the properties of Zr electrode and the oxide films that cover the metal surface is of extreme importance due to their wide applications in chemical and nuclear industry. In this thesis the electrochemical behaviour of Zr electrode in alkali halide solutions and with various surface conditions was studied, Also the galvanostatic oxidation of the metal in addition to the open circuit and impedance measurements were employed. Chapter I is a literature survey of the electrochemistry of Zr metal with particular emphasis on the stability and growth process of Zr in different media. Chapter II contains the experimental part, including details of the electrochemical techniques used in the measurements. The electrode impedance was always balanced as a series capacitance Cs and resistance Rs.Chapter III includes the experimental results and discussion. It is divide into sections, A and B. Section A includes the results of some experimental parameters which affect the reactivity of the oxide growth process on the zirconium surface, such as surface pre - treatment, electrolyte composition, the effect of different alkali halide anions, as well as the triiodide ion. 9 tabs.,26 figs.,67 refs

  15. Development of the method of sensitivity improvement of photographic film applicable in high-energy physics experiments

    International Nuclear Information System (INIS)

    Gokieli, V.D.

    1986-01-01

    Sensitivity improvement of photographic films applicable in high-energy physics experiments is discussed. To get optimal operating conditions for photographic film PT-6 to check its physical properties on electron beam and in cosmic rays a set for film samples exposure in visible spectrum and in X-rays is constructed. The set includes a start up device, high-voltage pulse oscillator, shapers, a chamber for the sample exposure, voltage divider and electron oscillograph

  16. Recovery of silver from waste photographic x-ray films

    International Nuclear Information System (INIS)

    Nartey, V.K.; Donkor, A.; Fianko, J.R.

    2005-01-01

    In this work, metallic silver has been recovered from disused X-ray films by leaching the silver (Ag) with 50% and 70% nitric acid(HNO 3 ) aqueous solutions. The films were collected from four hospitals in Accra. This method of retrieving Ag is more environmentally friendly compared with the current traditional technique employing dilute sulfuric acid (33%) by the indigenous population to win Ag. More so, the traditional method is characterized by the emission of toxic fuming gases (e.g. sulfur dioxide) and particulates (e.g. lead and arsenic compounds) during the refining of the Ag while reporting.Average yield of recovered Ag was 50.6% following the traditional method whereas 77.0% and 82.9% were obtained using 50% and 70% HNO 3 respectively. (au)

  17. Electron-stimulated desorption of lithium ions from lithium halide thin films

    International Nuclear Information System (INIS)

    Markowski, Leszek

    2007-01-01

    Electron-stimulated desorption of positive lithium ions from thin layers of lithium halides deposited onto Si(1 1 1) are investigated by the time-of-flight technique. The determined values of isotope effect of the lithium ( 6 Li + / 7 Li + ) are 1.60 ± 0.04, 1.466 ± 0.007, 1.282 ± 0.004, 1.36 ± 0.01 and 1.33 ± 0.01 for LiH, LiF, LiCl, LiBr and LiI, respectively. The observed most probable kinetic energies of 7 Li + are 1.0, 1.9, 1.1, 0.9 and 0.9 eV for LiH, LiF, LiCl, LiBr and LiI, respectively, and seem to be independent of the halide component mass. The values of lithium ion emission yield, lithium kinetic energy and lithium isotope effect suggest that the lattice relaxation is only important in the lithium ion desorption process from the LiH system. In view of possible mechanisms and processes involved into lithium ion desorption the obtained results indicate that for LiH, LiCl, LiBr and LiI the ions desorb in a rather classical way. However, for LiF, ion desorption has a more quantum character and the modified wave packet squeezing model has to be taken into account

  18. Charge carrier recombination channels in the low-temperature phase of organic-inorganic lead halide perovskite thin films

    Science.gov (United States)

    Wehrenfennig, Christian; Liu, Mingzhen; Snaith, Henry J.; Johnston, Michael B.; Herz, Laura M.

    2014-08-01

    The optoelectronic properties of the mixed hybrid lead halide perovskite CH3NH3PbI3-xClx have been subject to numerous recent studies related to its extraordinary capabilities as an absorber material in thin film solar cells. While the greatest part of the current research concentrates on the behavior of the perovskite at room temperature, the observed influence of phonon-coupling and excitonic effects on charge carrier dynamics suggests that low-temperature phenomena can give valuable additional insights into the underlying physics. Here, we present a temperature-dependent study of optical absorption and photoluminescence (PL) emission of vapor-deposited CH3NH3PbI3-xClx exploring the nature of recombination channels in the room- and the low-temperature phase of the material. On cooling, we identify an up-shift of the absorption onset by about 0.1 eV at about 100 K, which is likely to correspond to the known tetragonal-to-orthorhombic transition of the pure halide CH3NH3PbI3. With further decreasing temperature, a second PL emission peak emerges in addition to the peak from the room-temperature phase. The transition on heating is found to occur at about 140 K, i.e., revealing significant hysteresis in the system. While PL decay lifetimes are found to be independent of temperature above the transition, significantly accelerated recombination is observed in the low-temperature phase. Our data suggest that small inclusions of domains adopting the room-temperature phase are responsible for this behavior rather than a spontaneous increase in the intrinsic rate constants. These observations show that even sparse lower-energy sites can have a strong impact on material performance, acting as charge recombination centres that may detrimentally affect photovoltaic performance but that may also prove useful for optoelectronic applications such as lasing by enhancing population inversion.

  19. Charge carrier recombination channels in the low-temperature phase of organic-inorganic lead halide perovskite thin films

    Directory of Open Access Journals (Sweden)

    Christian Wehrenfennig

    2014-08-01

    Full Text Available The optoelectronic properties of the mixed hybrid lead halide perovskite CH3NH3PbI3−xClx have been subject to numerous recent studies related to its extraordinary capabilities as an absorber material in thin film solar cells. While the greatest part of the current research concentrates on the behavior of the perovskite at room temperature, the observed influence of phonon-coupling and excitonic effects on charge carrier dynamics suggests that low-temperature phenomena can give valuable additional insights into the underlying physics. Here, we present a temperature-dependent study of optical absorption and photoluminescence (PL emission of vapor-deposited CH3NH3PbI3−xClx exploring the nature of recombination channels in the room- and the low-temperature phase of the material. On cooling, we identify an up-shift of the absorption onset by about 0.1 eV at about 100 K, which is likely to correspond to the known tetragonal-to-orthorhombic transition of the pure halide CH3NH3PbI3. With further decreasing temperature, a second PL emission peak emerges in addition to the peak from the room-temperature phase. The transition on heating is found to occur at about 140 K, i.e., revealing significant hysteresis in the system. While PL decay lifetimes are found to be independent of temperature above the transition, significantly accelerated recombination is observed in the low-temperature phase. Our data suggest that small inclusions of domains adopting the room-temperature phase are responsible for this behavior rather than a spontaneous increase in the intrinsic rate constants. These observations show that even sparse lower-energy sites can have a strong impact on material performance, acting as charge recombination centres that may detrimentally affect photovoltaic performance but that may also prove useful for optoelectronic applications such as lasing by enhancing population inversion.

  20. Kinetic models for the development of density in photographic and radiographic film

    International Nuclear Information System (INIS)

    Darvell, B.W.; Prince Philip Dental Hospital, Hong Kong)

    1985-01-01

    The behaviour of radiographic and photographic films is usually described in terms of a plot of optical density against log (exposure). This form, based on a desired 'ideal' rather than any theory of the actual process, leads to difficulties of interpretation and arbitrary 'speed' determinations. Data collected have been shown to fit chemical kinetic models of differing order, depending on film and radiation type, with the rate constant providing a rational speed parameter. The order of the model seems to be associated with the number of quantum hits required for grain developability. A rational contrast index is proposed. (author)

  1. Preparation of textured high Tc superconducting films by CVD using halides on technical substrates with appropriate buffer layers. Final report

    International Nuclear Information System (INIS)

    Selbmann, D.; Balarin, M.; Klosowski, J.

    1993-01-01

    On the basis of a thermodynamical calculation of the system Y-Ba-Cu-O-Hal-C-H, Hal = I, Br, Cl the deposition conditions of the 123-phase and the other phases in this system was investigated. For the practical applications a reaction temperature higher 850 C and an oxidizer excesse higher 5 . 10 3 is necessary in order to deposit halid- and carbon free layers. A new Aerosol-CVD-process has been developed, which allows the reproducible preparation of superconducting YBa 2 Cu 3 O 7 thin films. The process uses a solution source of Y-, Ba-, Cu-bromide dissolved in suitable organic solvents. With the process the films consisting of the 123-phase, however the content of other phases is too high. With this composition it is not possible to deposit textured layers. This behaviour is due to flow technical problems. In order to avoid the formation of oxides in the evaporator it is necessary to mix the oxidizer directly near the substrate. Therefore the development of a new reactor and a process optimization is necessary. (orig.) [de

  2. Temperature-dependent excitonic photoluminescence of hybrid organometal halide perovskite films

    KAUST Repository

    Wu, Kewei; Bera, Ashok; Ma, Chun; Du, Yuanmin; Yang, Yang; LI, LIANG; Wu, Tao

    2014-01-01

    Organometal halide perovskites have recently attracted tremendous attention due to their potential for photovoltaic applications, and they are also considered as promising materials in light emitting and lasing devices. In this work, we investigated in detail the cryogenic steady state photoluminescence properties of a prototypical hybrid perovskite CH3NH3PbI3-xClx. The evolution of the characteristics of two excitonic peaks coincides with the structural phase transition around 160 K. Our results further revealed an exciton binding energy of 62.3 ± 8.9 meV and an optical phonon energy of 25.3 ± 5.2 meV, along with an abnormal blue-shift of the band gap in the high-temperature tetragonal phase. This journal is

  3. Process for forming epitaxial perovskite thin film layers using halide precursors

    Science.gov (United States)

    Clem, Paul G.; Rodriguez, Mark A.; Voigt, James A.; Ashley, Carol S.

    2001-01-01

    A process for forming an epitaxial perovskite-phase thin film on a substrate. This thin film can act as a buffer layer between a Ni substrate and a YBa.sub.2 Cu.sub.3 O.sub.7-x superconductor layer. The process utilizes alkali or alkaline metal acetates dissolved in halogenated organic acid along with titanium isopropoxide to dip or spin-coat the substrate which is then heated to about 700.degree. C. in an inert gas atmosphere to form the epitaxial film on the substrate. The YBCO superconductor can then be deposited on the layer formed by this invention.

  4. Preservation of photographic and cinematographic films by gamma radiation: Preliminary analyses

    Energy Technology Data Exchange (ETDEWEB)

    Nagai, Maria Luiza E.; Santos, Paulo S.; Otubo, Larissa; Oliveira, Maria José A.; Vasquez, Pablo A.S., E-mail: malunagai@usp.br, E-mail: pavsalva@ipen.br [Instituto de Pesquisas Energéticas e Nucleares (IPEN/CNEN-SP), São Paulo, SP (Brazil)

    2017-07-01

    Brazilian weather conditions affect directly tangible materials causing deterioration notably getting worse by insects and fungi attack. In this sense, gamma radiation provided from the cobalt-60 is an excellent alternative tool to the traditional preservation process mainly because it has biocidal action. Radiation processing using gamma radiation for cultural heritage materials for disinfection has been widely used around the world in the last decades. Many cultural heritage objects especially made on paper and wood were studied in scientific publications aiming mechanical, physical and chemical properties changes. Over the last fifteen years, the Multipurpose Gamma Irradiation Facility of the Nuclear and Energy Research Institute located inside the Sao Paulo University campus has been irradiated many collections of archived materials, books, paintings and furniture. Adequate storage of photographic and cinematographic materials is a challenge for conservators from preservation institutions. Contamination by fungi is one of leading causes of problem in photographic and cinematographic collections. Several Sao Paulo University libraries have been affected by fungi in their photographic and cinematographic collections making it impossible to research on these materials either manipulate them for health and safety reasons. In this work are presented preliminary results of effects of the ionizing radiation in photographic and cinematographic films. Selected film samples made on cellulose acetate were prepared and characterized by FTIR-ATR spectroscopy. Samples were irradiated by gamma rays with absorbed dose between 2 kGy and 50 kGy. Irradiated samples were analyzed by UV-VIS spectroscopy and electron microscopy techniques. Results shown that disinfection by gamma radiation can be achieved safely applying the disinfection dose between 6 kGy to 15 kGy with no significant change or modification of main properties of the constitutive materials. (author)

  5. Preservation of photographic and cinematographic films by gamma radiation: Preliminary analyses

    International Nuclear Information System (INIS)

    Nagai, Maria Luiza E.; Santos, Paulo S.; Otubo, Larissa; Oliveira, Maria José A.; Vasquez, Pablo A.S.

    2017-01-01

    Brazilian weather conditions affect directly tangible materials causing deterioration notably getting worse by insects and fungi attack. In this sense, gamma radiation provided from the cobalt-60 is an excellent alternative tool to the traditional preservation process mainly because it has biocidal action. Radiation processing using gamma radiation for cultural heritage materials for disinfection has been widely used around the world in the last decades. Many cultural heritage objects especially made on paper and wood were studied in scientific publications aiming mechanical, physical and chemical properties changes. Over the last fifteen years, the Multipurpose Gamma Irradiation Facility of the Nuclear and Energy Research Institute located inside the Sao Paulo University campus has been irradiated many collections of archived materials, books, paintings and furniture. Adequate storage of photographic and cinematographic materials is a challenge for conservators from preservation institutions. Contamination by fungi is one of leading causes of problem in photographic and cinematographic collections. Several Sao Paulo University libraries have been affected by fungi in their photographic and cinematographic collections making it impossible to research on these materials either manipulate them for health and safety reasons. In this work are presented preliminary results of effects of the ionizing radiation in photographic and cinematographic films. Selected film samples made on cellulose acetate were prepared and characterized by FTIR-ATR spectroscopy. Samples were irradiated by gamma rays with absorbed dose between 2 kGy and 50 kGy. Irradiated samples were analyzed by UV-VIS spectroscopy and electron microscopy techniques. Results shown that disinfection by gamma radiation can be achieved safely applying the disinfection dose between 6 kGy to 15 kGy with no significant change or modification of main properties of the constitutive materials. (author)

  6. Heteroepitaxial strain in alkali halide thin films: KCl on NaCl

    DEFF Research Database (Denmark)

    Baker, J.; Lindgård, Per-Anker

    1999-01-01

    We have pet-formed Monte Carlo simulations of the properties of a NaCl (001) surface covered by full or partial layers of KCl, for coverages up to 5 monolayers (ML). A wide variety of structures of the film is found. For integer ML coverages we find the continuous, so-called floating mode rumple ...

  7. Depletion-mode vertical Ga2O3 trench MOSFETs fabricated using Ga2O3 homoepitaxial films grown by halide vapor phase epitaxy

    Science.gov (United States)

    Sasaki, Kohei; Thieu, Quang Tu; Wakimoto, Daiki; Koishikawa, Yuki; Kuramata, Akito; Yamakoshi, Shigenobu

    2017-12-01

    We developed depletion-mode vertical Ga2O3 trench metal-oxide-semiconductor field-effect transistors by using n+ contact and n- drift layers. These epilayers were grown on an n+ (001) Ga2O3 single-crystal substrate by halide vapor phase epitaxy. Cu and HfO2 were used for the gate metal and dielectric film, respectively. The mesa width and gate length were approximately 2 and 1 µm, respectively. The devices showed good DC characteristics, with a specific on-resistance of 3.7 mΩ cm2 and clear current modulation. An on-off ratio of approximately 103 was obtained.

  8. Influence of growth temperature on bulk and surface defects in hybrid lead halide perovskite films

    Science.gov (United States)

    Peng, Weina; Anand, Benoy; Liu, Lihong; Sampat, Siddharth; Bearden, Brandon E.; Malko, Anton V.; Chabal, Yves J.

    2016-01-01

    The rapid development of perovskite solar cells has focused its attention on defects in perovskites, which are gradually realized to strongly control the device performance. A fundamental understanding is therefore needed for further improvement in this field. Recent efforts have mainly focused on minimizing the surface defects and grain boundaries in thin films. Using time-resolved photoluminescence spectroscopy, we show that bulk defects in perovskite samples prepared using vapor assisted solution process (VASP) play a key role in addition to surface and grain boundary defects. The defect state density of samples prepared at 150 °C (~1017 cm-3) increases by 5 fold at 175 °C even though the average grains size increases slightly, ruling out grain boundary defects as the main mechanism for the observed differences in PL properties upon annealing. Upon surface passivation using water molecules, the PL intensity and lifetime of samples prepared at 200 °C are only partially improved, remaining significantly lower than those prepared at 150 °C. Thus, the present study indicates that the majority of these defect states observed at elevated growth temperatures originates from bulk defects and underscores the importance to control the formation of bulk defects together with grain boundary and surface defects to further improve the optoelectronic properties of perovskites.The rapid development of perovskite solar cells has focused its attention on defects in perovskites, which are gradually realized to strongly control the device performance. A fundamental understanding is therefore needed for further improvement in this field. Recent efforts have mainly focused on minimizing the surface defects and grain boundaries in thin films. Using time-resolved photoluminescence spectroscopy, we show that bulk defects in perovskite samples prepared using vapor assisted solution process (VASP) play a key role in addition to surface and grain boundary defects. The defect state

  9. Atomic Layer Deposition of Electron Selective SnOx and ZnO Films on Mixed Halide Perovskite: Compatibility and Performance.

    Science.gov (United States)

    Hultqvist, Adam; Aitola, Kerttu; Sveinbjörnsson, Kári; Saki, Zahra; Larsson, Fredrik; Törndahl, Tobias; Johansson, Erik; Boschloo, Gerrit; Edoff, Marika

    2017-09-06

    The compatibility of atomic layer deposition directly onto the mixed halide perovskite formamidinium lead iodide:methylammonium lead bromide (CH(NH 2 ) 2 , CH 3 NH 3 )Pb(I,Br) 3 (FAPbI 3 :MAPbBr 3 ) perovskite films is investigated by exposing the perovskite films to the full or partial atomic layer deposition processes for the electron selective layer candidates ZnO and SnO x . Exposing the samples to the heat, the vacuum, and even the counter reactant of H 2 O of the atomic layer deposition processes does not appear to alter the perovskite films in terms of crystallinity, but the choice of metal precursor is found to be critical. The Zn precursor Zn(C 2 H 5 ) 2 either by itself or in combination with H 2 O during the ZnO atomic layer deposition (ALD) process is found to enhance the decomposition of the bulk of the perovskite film into PbI 2 without even forming ZnO. In contrast, the Sn precursor Sn(N(CH 3 ) 2 ) 4 does not seem to degrade the bulk of the perovskite film, and conformal SnO x films can successfully be grown on top of it using atomic layer deposition. Using this SnO x film as the electron selective layer in inverted perovskite solar cells results in a lower power conversion efficiency of 3.4% than the 8.4% for the reference devices using phenyl-C 70 -butyric acid methyl ester. However, the devices with SnO x show strong hysteresis and can be pushed to an efficiency of 7.8% after biasing treatments. Still, these cells lacks both open circuit voltage and fill factor compared to the references, especially when thicker SnO x films are used. Upon further investigation, a possible cause of these losses could be that the perovskite/SnO x interface is not ideal and more specifically found to be rich in Sn, O, and halides, which is probably a result of the nucleation during the SnO x growth and which might introduce barriers or alter the band alignment for the transport of charge carriers.

  10. The Role of Photographs and Films in Kettlewell's Popularizations of the Phenomenon of Industrial Melanism

    Science.gov (United States)

    Wÿss Rudge, David

    H.B.D. Kettlewell's investigations on the phenomenon of industrial melanism are generally referred to in textbooks and other popularizations of science as the classic demonstration of natural selection (Majerus 1989). A central question for historians of this episode is accounting for why public perceptions of the importance of Kettlewell's work have diverged from those of researchers who actually work on the phenomenon. In a recent paper published in Biology and Philosophy, Joel Hagen draws attention to the role Kettlewell and his colleagues played in idealizing his investigations as an example of controlled experimentation in their several retrospective popular accounts. The present essay discusses the important role photographic and film depictions of differential bird predation played in Kettlewell's popularizations. This analysis supports Hagen's contentions that Kettlewell deftly and strategically used these visual representations to command assent to his interpretation of the phenomenon and shore up claims about the scientific legitimacy and importance of his work. It nevertheless disputes that these images were intended to portray Kettlewell's experiments as an example of controlled experimentation. In a concluding section, the essay draws several morals from this analysis regarding the use of popularized articles and visual images to teach science.

  11. Influence of PbCl2 content in PbI2 solution of DMF on the absorption, crystal phase, morphology of lead halide thin films and photovoltaic performance in planar perovskite solar cells

    International Nuclear Information System (INIS)

    Wang, Mao; Shi, Chengwu; Zhang, Jincheng; Wu, Ni; Ying, Chao

    2015-01-01

    In this paper, the influence of PbCl 2 content in PbI 2 solution of DMF on the absorption, crystal phase and morphology of lead halide thin films was systematically investigated and the photovoltaic performance of the corresponding planar perovskite solar cells was evaluated. The result revealed that the various thickness lead halide thin film with the small sheet-like, porous morphology and low crystallinity can be produced by adding PbCl 2 powder into PbI 2 solution of DMF as a precursor solution. The planar perovskite solar cell based on the 300-nm-thick CH 3 NH 3 PbI 3−x Cl x thin film by the precursor solution with the mixture of 0.80 M PbI 2 and 0.20 M PbCl 2 exhibited the optimum photoelectric conversion efficiency of 10.12% along with an open-circuit voltage of 0.93 V, a short-circuit photocurrent density of 15.70 mA cm −2 and a fill factor of 0.69. - Graphical abstract: The figure showed the surface and cross-sectional SEM images of lead halide thin films using the precursor solutions: (a) 0.80 M PbI 2 , (b) 0.80 M PbI 2 +0.20 M PbCl 2 , (c) 0.80 M PbI 2 +0.40 M PbCl 2 , and (d) 0.80 M PbI 2 +0.60 M PbCl 2 . With the increase of the PbCl 2 content in precursor solution, the size of the lead halide nanosheet decreased and the corresponding thin films gradually turned to be porous with low crystallinity. - Highlights: • Influence of PbCl 2 content on absorption, crystal phase and morphology of thin film. • Influence of perovskite film thickness on photovoltaic performance of solar cell. • Lead halide thin film with small sheet-like, porous morphology and low crystallinity. • Planar solar cell with 300 nm-thick perovskite thin film achieved PCE of 10.12%.

  12. The Role of Trap-assisted Recombination in Luminescent Properties of Organometal Halide CH3NH3PbBr3 Perovskite Films and Quantum Dots

    Science.gov (United States)

    Zhang, Zhen-Yu; Wang, Hai-Yu; Zhang, Yan-Xia; Hao, Ya-Wei; Sun, Chun; Zhang, Yu; Gao, Bing-Rong; Chen, Qi-Dai; Sun, Hong-Bo

    2016-06-01

    Hybrid metal halide perovskites have been paid enormous attentions in photophysics research, whose excellent performances were attributed to their intriguing charge carriers proprieties. However, it still remains far from satisfaction in the comprehensive understanding of perovskite charge-transport properities, especially about trap-assisted recombination process. In this Letter, through time-resolved transient absorption (TA) and photoluminescence (PL) measurements, we provided a relative comprehensive investigation on the charge carriers recombination dynamics of CH3NH3PbBr3 (MAPbBr3) perovskite films and quantum dots (QDs), especially about trap-assisted recombination. It was found that the integral recombination mode of MAPbBr3 films was highly sensitive to the density distribution of generated charge carriers and trap states. Additional, Trap effects would be gradually weakened with elevated carrier densities. Furthermore, the trap-assisted recombination can be removed from MAPbBr3 QDs through its own surface passivation mechanism and this specialty may render the QDs as a new material in illuminating research. This work provides deeper physical insights into the dynamics processes of MAPbBr3 materials and paves a way toward more light-harvesting applications in future.

  13. Fabrication of large area plasmonic nanoparticle grating structure on silver halide based transmission electron microscope film and its application as a surface enhanced Raman spectroscopy substrate

    International Nuclear Information System (INIS)

    Sudheer,; Tiwari, P.; Singh, M. N.; Sinha, A. K.; Rai, V. N.; Srivastava, A. K.; Bhartiya, S.; Mukherjee, C.

    2015-01-01

    The plasmonic responses of silver nanoparticle grating structures of different periods made on silver halide based electron microscope film are investigated. Raster scan of the conventional scanning electron microscope (SEM) is used to carry out electron beam lithography for fabricating the plasmonic nanoparticle grating (PNG) structures. Morphological characterization of the PNG structures, carried out by the SEM and the atomic force microscope, indicates that the depth of the groove decreases with a decrease in the grating period. Elemental characterization performed by the energy dispersive spectroscopy and the x-ray diffraction shows the presence of nanoparticles of silver in the PNG grating. The optical characterization of the gratings shows that the localized surface plasmon resonance peak shifts from 366 to 378 nm and broadens with a decrease in grating period from 10 to 2.5 μm. The surface enhanced Raman spectroscopy of the Rhodamine-6G dye coated PNG structure shows the maximum enhancement by two orders of magnitude in comparison to the randomly distributed silver nanoparticles having similar size and shape as the PNG structure

  14. The calibration of photographic and spectroscopic films. A densitometric analysis of IIaO film flown aboard the space shuttle transportation system STS3, STS8, and STS7

    Science.gov (United States)

    Hammond, Ernest C., Jr.

    1987-01-01

    The results of these studies have implications for the utilization of the IIaO spectroscopic film on the future shuttle and space lab missions. These responses to standard photonic energy sources will have immediate application for the uneven responses of the film photographing a star field in a terrestrial or extraterrestrial environment with associated digital imaging equipment.

  15. Effects of Solution-Based Fabrication Conditions on Morphology of Lead Halide Perovskite Thin Film Solar Cells

    Directory of Open Access Journals (Sweden)

    Jeremy L. Barnett

    2016-01-01

    Full Text Available We present a critical review of the effects of processing conditions on the morphology of methylammonium lead iodide (CH3NH3PbI3 perovskite solar cells. Though difficult to decouple from synthetic and film formation effects, a single morphological feature, specifically grain size, has been evidently linked to the photovoltaic performance of this class of solar cells. Herein, we discuss experimental aspects of optimizing the (a temperature and time of annealing, (b spin-coating parameters, and (c solution temperature of methylammonium iodide (MAI solution.

  16. Aerial photographs with infra-red film to survey injury to vegetation in Styria

    Energy Technology Data Exchange (ETDEWEB)

    Pollanschuetz, J

    1973-01-01

    This paper describes a successful operation in which injuries to Norway Spruce, chiefly caused by SO/sub 2/ pollution from smelters, was mapped from the air. Four zones varying in the severity of injury could be distinguished. They were characterized chiefly by differences in the number and age of needles present on the trees. The fourth zone contained only scattered, severely injured, but apparently highly resistant individual trees of Spruce. The photographs, however, did not reveal injuries that were not already visible to the naked eye. The relative resistance to air pollution of Blaufichte (Picea glauca) was noticed incidentally. 6 references.

  17. Colored tracks of heavy ion particles recorded on photographic color film

    International Nuclear Information System (INIS)

    Kuge, K.; Yasuda, N.; Kumagai, H.; Aoki, N.; Hasegawa, A.

    2002-01-01

    A new method to obtain the three-dimensional information on nuclear tracks was developed using color photography. Commercial color films were irradiated with ion beam and color-developed. The ion tracks were represented with color images in which different depths were indicated by different colors, and the three-dimensional information was obtained from color changes. Details of this method are reported, and advantages and limitations are discussed in comparison with a conventional method using a nuclear emulsion

  18. Forehardened photographic elements and their use in radiography

    International Nuclear Information System (INIS)

    Dickerson, R.E.

    1983-01-01

    This U.K. patent application relates to forehardened photographic elements, particularly radiographic elements having among hydrophilic colloid layers at least one emulsion layer wherein thin tabular silver halide grains having a thickness of less than 0.3 micrometer provide at least 50 percent of the total projected grain area. When developed in less than 1 minute to produce a viewable silver image, these photographic elements exhibit increased covering power. Methods of preparing the tabular grain silver halide emulsions are described. (author)

  19. Photofragmentation of metal halides

    International Nuclear Information System (INIS)

    Veen, N.J.A. van.

    1980-01-01

    The author deals with photodissociation of molecules of alkali halides. It is shown that the total absorption cross section consists of two contributions arising from transitions to excited states of total electronic angular momentum Ω=0 + and Ω=1. From the inversion of the absorption continua potential energy curves of the excited states can be constructed in the Franck-Condon region. It is found that for all alkali halides the 0 + state is higher in energy than the Ω=1 state. Extensive studies are reported on three thallium halides, TlI, TlBr and TlCl at various wavelengths covering the near ultraviolet region. (Auth.)

  20. Entropy in halide perovskites

    Science.gov (United States)

    Katan, Claudine; Mohite, Aditya D.; Even, Jacky

    2018-05-01

    Claudine Katan, Aditya D. Mohite and Jacky Even discuss the possible impact of various entropy contributions (stochastic structural fluctuations, anharmonicity and lattice softness) on the optoelectronic properties of halide perovskite materials and devices.

  1. Possibilities to improve sensitivity and rendering of detail of streamer chamber track photographs

    Energy Technology Data Exchange (ETDEWEB)

    Baehr, J

    1975-01-01

    Streamer chambers are increasingly used as effective particle detectors in the field of experimental elementary particle physics. The photographic recording of high energy events in streamer chambers is limited by performance of current photographic silver-halide layers. Similar limiting problems occur in other fields as well, e.g., in astronomy, x-ray medicine and photogrammetry; therefore methods have been developed to increase sensitivity and improve the information transfer of the emulsion. In this paper these methods have been classified and summarized under the aspect of their application to streamer image recording. Proposals for further investigations are given. Especially the applicability of these methods, their possibility of combination to large film lengths should be investigated The detective quantum efficiency (DQE) is proposed as criterion to estimate and compare the different methods.

  2. Role of the chemical substitution on the structural and luminescence properties of the mixed halide perovskite thin MAPbI{sub 3−x}Br{sub x} (0 ≤ x ≤ 1) films

    Energy Technology Data Exchange (ETDEWEB)

    Atourki, Lahoucine, E-mail: lahoucine.atourki@edu.uiz.ac.ma [Materials and Renewable Energy Laboratory, Faculty of Science, Ibn Zohr University, Agadir (Morocco); Vega, Erika; Marí, Bernabé; Mollar, Miguel [Instituto de Diseño y Fabricación (IDF), Universitat Politécnica de València, València (Spain); Ait Ahsaine, Hassan [Laboratoire Matériaux et environnement LME, Faculté des Sciences d' Agadir, Université Ibn Zohr, Agadir (Morocco); Bouabid, Khalid; Ihlal, Ahmed [Materials and Renewable Energy Laboratory, Faculty of Science, Ibn Zohr University, Agadir (Morocco)

    2016-05-15

    Highlights: • X-ray diffraction analyses indicate the formation of a tetragonal phase I4/mcm up to x = 0.4 and a cubic perovskite with space group Pm3 m across in the composition range of 0.6 ≤ x ≤ 1. • Perovskite films exhibit a very high absorbance in the visible and short infrared. • As the fraction of bromide change, the adsorption edge of thin film perovskite can be tuned along the visible spectrum from 543 nm to 785 nm. • The incorporating of bromide into MAPbI{sub 3−x}Br{sub x} shifts the PL emission to shorter wavelengths. - Abstract: Mixed bromide iodide lead perovskites were prepared from methylamine, lead nitrate and the corresponding hydroX acid (X = I, Br), they were then deposited as thin films on ITO substrate by the spin coating process. X-ray diffraction analyses indicated the formation of a tetragonal phase I4/mcm up to x = 0.4 and a cubic perovskite with space group Pm3 m in the composition range of 0.6 ≤ x ≤ 1. Mixed lead perovskites showed a high absorbance in the UV–vis range. The band gap energy of thin films were estimated from absorbance spectral measurements, it was found that the onset of the absorption edge for MAPbI{sub 3−x}Br{sub x} (x < 1) thin films is ranging between 1.58 to 1.72 eV. Photoluminescence emission energies for mixed halide perovskites presented intermediate values from 781 nm (MAPbI{sub 3}) to 545 nm (MAPbBr{sub 3}).

  3. Role of the chemical substitution on the structural and luminescence properties of the mixed halide perovskite thin MAPbI_3_−_xBr_x (0 ≤ x ≤ 1) films

    International Nuclear Information System (INIS)

    Atourki, Lahoucine; Vega, Erika; Marí, Bernabé; Mollar, Miguel; Ait Ahsaine, Hassan; Bouabid, Khalid; Ihlal, Ahmed

    2016-01-01

    Highlights: • X-ray diffraction analyses indicate the formation of a tetragonal phase I4/mcm up to x = 0.4 and a cubic perovskite with space group Pm3 m across in the composition range of 0.6 ≤ x ≤ 1. • Perovskite films exhibit a very high absorbance in the visible and short infrared. • As the fraction of bromide change, the adsorption edge of thin film perovskite can be tuned along the visible spectrum from 543 nm to 785 nm. • The incorporating of bromide into MAPbI_3_−_xBr_x shifts the PL emission to shorter wavelengths. - Abstract: Mixed bromide iodide lead perovskites were prepared from methylamine, lead nitrate and the corresponding hydroX acid (X = I, Br), they were then deposited as thin films on ITO substrate by the spin coating process. X-ray diffraction analyses indicated the formation of a tetragonal phase I4/mcm up to x = 0.4 and a cubic perovskite with space group Pm3 m in the composition range of 0.6 ≤ x ≤ 1. Mixed lead perovskites showed a high absorbance in the UV–vis range. The band gap energy of thin films were estimated from absorbance spectral measurements, it was found that the onset of the absorption edge for MAPbI_3_−_xBr_x (x < 1) thin films is ranging between 1.58 to 1.72 eV. Photoluminescence emission energies for mixed halide perovskites presented intermediate values from 781 nm (MAPbI_3) to 545 nm (MAPbBr_3).

  4. New applications of photographic materials in science and technique

    International Nuclear Information System (INIS)

    Buschmann, H.T.; Deml, R.; Duville, R.; Philippaerts, H.; Bollen, R.; Ranz, E.

    1976-01-01

    In spite of some disatvantages photographic materials based on silver halides possess the outstanding feature of high sensitivity. So again and again special photographic materials have been developed for new techniques including information storage. This contribution reports on some special photographic materials and it briefly discusses some applications. Materials are discussed in detail for holography, carrier-frequency photography, producing masks for integrated circuits, recording equidensities, bubble chamber photography, and for neutron-radiography. (orig.) [de

  5. Making and Breaking of Lead Halide Perovskites

    KAUST Repository

    Manser, Joseph S.

    2016-02-16

    A new front-runner has emerged in the field of next-generation photovoltaics. A unique class of materials, known as organic metal halide perovskites, bridges the gap between low-cost fabrication and exceptional device performance. These compounds can be processed at low temperature (typically in the range 80–150 °C) and readily self-assemble from the solution phase into high-quality semiconductor thin films. The low energetic barrier for crystal formation has mixed consequences. On one hand, it enables inexpensive processing and both optical and electronic tunability. The caveat, however, is that many as-formed lead halide perovskite thin films lack chemical and structural stability, undergoing rapid degradation in the presence of moisture or heat. To date, improvements in perovskite solar cell efficiency have resulted primarily from better control over thin film morphology, manipulation of the stoichiometry and chemistry of lead halide and alkylammonium halide precursors, and the choice of solvent treatment. Proper characterization and tuning of processing parameters can aid in rational optimization of perovskite devices. Likewise, gaining a comprehensive understanding of the degradation mechanism and identifying components of the perovskite structure that may be particularly susceptible to attack by moisture are vital to mitigate device degradation under operating conditions. This Account provides insight into the lifecycle of organic–inorganic lead halide perovskites, including (i) the nature of the precursor solution, (ii) formation of solid-state perovskite thin films and single crystals, and (iii) transformation of perovskites into hydrated phases upon exposure to moisture. In particular, spectroscopic and structural characterization techniques shed light on the thermally driven evolution of the perovskite structure. By tuning precursor stoichiometry and chemistry, and thus the lead halide charge-transfer complexes present in solution, crystallization

  6. Current state and perspectives for organo-halide perovskite solar cells. Part 1. Crystal structures and thin film formation, morphology, processing, degradation, stability improvement by carbon nanotubes. A review

    Directory of Open Access Journals (Sweden)

    Nigmat Ashurov

    2017-03-01

    Full Text Available The fundamental problems of the modern state of the studies of organic–inorganic organo-halide perovskites (OHP as basis for high efficiency thin film solar cells are discussed. Perovskite varieties and background properties are introduced. The chronology of development of the studies in this direction has been presented – structural aspects of these OHP perovskites, from early 2D to recent 3D MAPbI3 perovskites and important technological aspects of smooth thin film structure creation by various techniques, such as solvent engineering, spin- and dip - coating, vacuum deposition, cation exchange approach, nanoimprinting (particularly, a many-sided role of polymers. The most important theoretical problems such as electronic structure of lattice, impurity and defect states in pure and mixed perovskites, suppressed electron-hole recombination, extra-long lifetimes, and diffusion lengths are analyzed. Degradation effects associated with moisture and photo irradiation, as well as degradation of metallic electrodes to OHP solar cells have been considered. The application of carbon nanostructures: carbon nanotubes (CNT and graphene as stable semitransparent charge collectors to OHP perovskites is demonstrated on the example of original results of authors.

  7. Method of making stepped photographic density standards of radiographic photographs

    International Nuclear Information System (INIS)

    Borovin, I.V.; Kondina, M.A.

    1987-01-01

    In industrial radiography practice the need often arises for a prompt evaluation of the photographic density of an x-ray film. A method of making stepped photographic density standards for industrial radiography by contact printing from a negative is described. The method is intended for industrial radiation flaw detection laboratories not having specialized sensitometric equipment

  8. Radiography using photographic paper

    International Nuclear Information System (INIS)

    Gromov, Yu.V.; Kapustin, V.I.; Volkova, T.G.

    1982-01-01

    The possibility of radiographic control with application of ''Fototelegrafnaya BS'' photographic paper in conjunction with the ''Standart'' image intensifier as an X-ray image converter is studied. Investigations were made using steel samples 5 to 45 mm thick, X-ray radiation energy varied from 80 to 240 keV. Specifications of the image intensifier of the ''Standart type and photographic paper are given. It is shown, that the photographic paper improves the sensitivity of the method to the detection of small defects. The method provides standard and panoramic radioscopy, conservation of objective documentation, enables one to mechanize and automatize the process of photodevelopment. The application of the photographic paper is beneficial, its cost being six times as low as that of X-ray film

  9. Impact of the organic halide salt on final perovskite composition for photovoltaic applications

    KAUST Repository

    Moore, David T.

    2014-08-01

    The methylammonium lead halide perovskites have shown significant promise as a low-cost, second generation, photovoltaic material.Despite recent advances, however, there are still a number of fundamental aspects of their formation as well as their physical and electronic behavior that are not well understood. In this letter we explore the mechanism by which these materials crystallize by testing the outcome of each of the reagent halide salts. We find that components of both salts, lead halide and methylammonium halide, are relatively mobile and can be readily exchanged during the crystallization process when the reaction is carried out in solution or in the solid state. We exploit this fact by showing that the perovskite structure is formed even when the lead salt\\'s anion is a non-halide, leading to lower annealing temperature and time requirements for film formation. Studies into these behaviors may ultimately lead to improved processing conditions for photovoltaic films. © 2014 Author(s).

  10. Impact of the organic halide salt on final perovskite composition for photovoltaic applications

    Directory of Open Access Journals (Sweden)

    David T. Moore

    2014-08-01

    Full Text Available The methylammonium lead halide perovskites have shown significant promise as a low-cost, second generation, photovoltaic material. Despite recent advances, however, there are still a number of fundamental aspects of their formation as well as their physical and electronic behavior that are not well understood. In this letter we explore the mechanism by which these materials crystallize by testing the outcome of each of the reagent halide salts. We find that components of both salts, lead halide and methylammonium halide, are relatively mobile and can be readily exchanged during the crystallization process when the reaction is carried out in solution or in the solid state. We exploit this fact by showing that the perovskite structure is formed even when the lead salt's anion is a non-halide, leading to lower annealing temperature and time requirements for film formation. Studies into these behaviors may ultimately lead to improved processing conditions for photovoltaic films.

  11. Copper(I) Thiocyanate (CuSCN) Hole-Transport Layers Processed from Aqueous Precursor Solutions and Their Application in Thin-Film Transistors and Highly Efficient Organic and Organometal Halide Perovskite Solar Cells

    KAUST Repository

    Wijeyasinghe, Nilushi

    2017-07-28

    This study reports the development of copper(I) thiocyanate (CuSCN) hole-transport layers (HTLs) processed from aqueous ammonia as a novel alternative to conventional n-alkyl sulfide solvents. Wide bandgap (3.4–3.9 eV) and ultrathin (3–5 nm) layers of CuSCN are formed when the aqueous CuSCN–ammine complex solution is spin-cast in air and annealed at 100 °C. X-ray photoelectron spectroscopy confirms the high compositional purity of the formed CuSCN layers, while the high-resolution valence band spectra agree with first-principles calculations. Study of the hole-transport properties using field-effect transistor measurements reveals that the aqueous-processed CuSCN layers exhibit a fivefold higher hole mobility than films processed from diethyl sulfide solutions with the maximum values approaching 0.1 cm2 V−1 s−1. A further interesting characteristic is the low surface roughness of the resulting CuSCN layers, which in the case of solar cells helps to planarize the indium tin oxide anode. Organic bulk heterojunction and planar organometal halide perovskite solar cells based on aqueous-processed CuSCN HTLs yield power conversion efficiency of 10.7% and 17.5%, respectively. Importantly, aqueous-processed CuSCN-based cells consistently outperform devices based on poly(3,4-ethylenedioxythiophene) polystyrene sulfonate HTLs. This is the first report on CuSCN films and devices processed via an aqueous-based synthetic route that is compatible with high-throughput manufacturing and paves the way for further developments.

  12. Metal induced gap states at alkali halide/metal interface

    International Nuclear Information System (INIS)

    Kiguchi, Manabu; Yoshikawa, Genki; Ikeda, Susumu; Saiki, Koichiro

    2004-01-01

    The electronic state of a KCl/Cu(0 0 1) interface was investigated using the Cl K-edge near-edge X-ray absorption fine structure (NEXAFS). A pre-peak observed on the bulk edge onset of thin KCl films has a similar feature to the peak at a LiCl/Cu(0 0 1) interface, which originates from the metal induced gap state (MIGS). The present result indicates that the MIGS is formed universally at alkali halide/metal interfaces. The decay length of MIGS to an insulator differs from each other, mainly due to the difference in the band gap energy of alkali halide

  13. Heavenly bodies the photographer's guide to astrophotography

    CERN Document Server

    Krages, Esq, Bert P

    2003-01-01

    Detailing the photographic equipment and astronomical instruments needed to capture celestial images, this guide shows how astrophotography can be accessible to all photographers. Included is a detailed introduction to basic astronomy with information on mapping the sky, locating celestial bodies, and planning an expedition to photograph astronomical phenomena. Photographers learn how to determine the color sensitivity of various films and achieve the best possible exposure, how to ensure a captivating composition, and how commercially processed prints can support their artistic vision. Whethe

  14. Resonant halide perovskite nanoparticles

    Science.gov (United States)

    Tiguntseva, Ekaterina Y.; Ishteev, Arthur R.; Komissarenko, Filipp E.; Zuev, Dmitry A.; Ushakova, Elena V.; Milichko, Valentin A.; Nesterov-Mueller, Alexander; Makarov, Sergey V.; Zakhidov, Anvar A.

    2017-09-01

    The hybrid halide perovskites is a prospective material for fabrication of cost-effective optical devices. Unique perovskites properties are used for solar cells and different photonic applications. Recently, perovskite-based nanophotonics has emerged. Here, we consider perovskite like a high-refractive index dielectric material, which can be considered to be a basis for nanoparticles fabrication with Mie resonances. As a result, we fabricate and study resonant perovskite nanoparticles with different sizes. We reveal, that spherical nanoparticles show enhanced photoluminescence signal. The achieved results lay a cornerstone in the field of novel types of organic-inorganic nanophotonics devices with optical properties improved by Mie resonances.

  15. Anatomic localization of scintillation colour image by means of simultaneous colour polaroid film photographing of emission scintiphoto and transmission scintiphoto

    International Nuclear Information System (INIS)

    Kida, Toshiyuki; Suzuki, Akira; Kobayashi, Katsuko

    1977-01-01

    A study has been made of a simple and practical method to add information of anatomical localization upon the emission scintiphoto of the generally used polaroid film. First, a polaroid film of a transmission scintiphoto, according to the Anger method, was made, and then, that of an emission scintiphoto was made. Next, by double-exposing these two photos to the same polaroid film with the Mamiya-made duplicator, these photos were made into a composite photo. In that case, in order to distinguish the images of these scintiphotos on this composite photo, a colour polaroid film was used in the double exposure, and here, when each of the two scintiphotos was given its own colour-filter, it was found that the image could be sharply sorted by colour. This method does not require any highly expensive apparatus; and, according to this method, a disc source and a polaroid duplicator are enough for the exact anatomical localization of scintiphoto-images by the polaroid film. (auth.)

  16. Characterization of cinematographic films by Laser Induced Breakdown Spectroscopy

    International Nuclear Information System (INIS)

    Gaspard, S.; Oujja, M.; Rebollar, E.; Abrusci, C.; Catalina, F.; Castillejo, M.

    2007-01-01

    The emulsion-coated transparent plastic-base film has been the main carrier for production and preservation of motion picture contents since the 19th century. The knowledge of the composition of black and white silver gelatine cinematographic films is of great importance for the characterization of the photographic process and for identifying the optimum conditions for conservation. A cinematographic film is a multi-component system that consists of a layer of photographic emulsion overcoating a polymeric support (plasticized cellulose triacetate) and a protective transparent cross-linked gelatine layer coating the emulsion. In the present work, Laser Induced Breakdown Spectroscopy (LIBS) is used to characterize the composition of the materials of cinematographic films. LIB spectra of film samples and of different individual film components, polymeric support and reference gelatines, were acquired in vacuum by excitation at 266 nm (Q-switched Nd:YAG laser, 6 ns, 10 Hz). In the cinematographic film, silver lines from the light-sensitive silver halide salts of the photographic emulsion are accompanied by iron, lead, chrome and phosphorus lines. Iron and lead are constituents of film developers, chrome is included in the composition of the hardening agents and phosphorus has its origin in the plasticizer used in the polymeric support. By applying successive pulses on the same spot of the film sample, it was possible to observe through stratigraphic analysis the different layers composition. Additionally, the results obtained reveal the analytical capacity of LIBS for the study and classification of the different gelatine types and qualities used for the protecting layer and the photographic emulsion

  17. Salvaging and Conserving Water Damaged Photographic Materials

    Science.gov (United States)

    Suzuki, Ryuji

    Degradation of water damaged photographic materials is discussed; the most vulnerable elements are gelatin layers and silver image. A simple and inexpensive chemical treatment is proposed, consisting of a bath containing a gelatin-protecting biocide and a silver image protecting agent. These ingredients were selected among those used in manufacturing of silver halide photographic emulsions or processing chemicals. Experiments confirmed that this treatment significantly reduced oxidative attacks to silver image and bacterial degradation of gelatin layers. The treated material was also stable under intense light fading test. Method of hardening gelatin to suppress swelling is also discussed.

  18. Single Crystals of Organolead Halide Perovskites: Growth, Characterization, and Applications

    KAUST Repository

    Peng, Wei

    2017-04-01

    With the soaring advancement of organolead halide perovskite solar cells rising from a power conversion efficiency of merely 3% to more than 22% shortly in five years, researchers’ interests on this big material family have been greatly spurred. So far, both in-depth studies on the fundamental properties of organolead halide perovskites and their extended applications such as photodetectors, light emitting diodes, and lasing have been intensively reported. The great successes have been ascribed to various superior properties of organolead halide hybrid perovskites such as long carrier lifetimes, high carrier mobility, and solution-processable high quality thin films, as will be discussed in Chapter 1. Notably, most of these studies have been limited to their polycrystalline thin films. Single crystals, as a counter form of polycrystals, have no grain boundaries and higher crystallinity, and thus less defects. These characteristics gift single crystals with superior optical, electrical, and mechanical properties, which will be discussed in Chapter 2. For example, organolead halide perovskite single crystals have been reported with much longer carrier lifetimes and higher carrier mobilities, which are especially intriguing for optoelectronic applications. Besides their superior optoelectronic properties, organolead halide perovskites have shown large composition versatility, especially their organic components, which can be controlled to effectively adjust their crystal structures and further fundamental properties. Single crystals are an ideal platform for such composition-structure-property study since a uniform structure with homogeneous compositions and without distraction from grain boundaries as well as excess defects can provide unambiguously information of material properties. As a major part of work of this dissertation, explorative work on the composition-structure-property study of organic-cation-alloyed organolead halide perovskites using their single

  19. The first demonstration of room temperature stimulated emission from metal halides -its evidence in CsPbBr3 films

    OpenAIRE

    中西, 貴之; 高橋, 一彰; 斎藤, 忠昭; 近藤, 新一

    2005-01-01

    Photoluminescence from CsPbBr3 films prepared by crystallization from the amorphous phase is measured under N2 laser excitation. Stimulated emission due to free exaction-free exaction inelastic collision occurs not only at cryogenic temperature but also elevated temperatures. The intensity of the stimulated emission more rapidly increases with pumping intensity at room temperature than at 77K. The temperature dependence of the stimulated emission measured under 1100kW cm-2 pumping shows th...

  20. Oblique Photographs

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set includes photographs of marine mammals and sea turtles taken in the field. Most are lateral views of animals that are used to confirm species identity...

  1. Vertical Photographs

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set includes of photographs of marine mammals and sea turtles taken with high resolution cameras mounted in airplanes, unmanned platforms or the bow of...

  2. Computer aided photographic engineering

    Science.gov (United States)

    Hixson, Jeffrey A.; Rieckhoff, Tom

    1988-01-01

    High speed photography is an excellent source of engineering data but only provides a two-dimensional representation of a three-dimensional event. Multiple cameras can be used to provide data for the third dimension but camera locations are not always available. A solution to this problem is to overlay three-dimensional CAD/CAM models of the hardware being tested onto a film or photographic image, allowing the engineer to measure surface distances, relative motions between components, and surface variations.

  3. X-radiography using photographic papers

    International Nuclear Information System (INIS)

    Nitiyaporn, W.

    1986-01-01

    The objective of this research is to study the possibility of using photographic paper, available on the market, for x-ray radiography instead of x-ray film which is more expensive and more complicate to develop. This research concerned about (1) the method and the limitation of x-ray radiography by using 3 types of photographic paper, namely, F2, F3 and F4 distributed by the Kodak Company, as the screen with 3 different kinds of intensifying screens produced by the Phillips Company, Toshiba Company and Picker Company to increase photographic efficiency; (2) correction factor between these 3 types of photographic paper and intensifying screens; (3) the most suitable combination of photographic paper and intensifying screens used; (4) the result of using photographic paper and x-ray film in x-ray radiography regarding quality, cost and film developing. From the research, it was found that (1) the combination of intensifying screen from Picker Company and Kodak photographic paper No. F4 coating with silver bromide with a little mixture of silver iodide resulted in higher sensitivity and more contrast than other combination; (2) photographic papers had more limitation than x-ray film in the sense that it could be used with the iron test piece no thicker than 3 cm.with the x-ray energy of 220 k Vp; (3) photographic papers would give almost the same degree of contrast and sensitivity as x-ray film when used with thin test specimens. For instance the smallest wire No.12 of DIN 62 FE could be seen in the photographic paper at 220 k Vp while it could be seen in the x-ray film at 200 k Vp while it could be seen in the x-ray film at 200 k Vp. The exposure of photographic paper would be in vicinity of x-ray film when it was used with thin test specimens. Photographic paper would produce sharpness definition, density and contrast picture and also details of the picture closely to what given by x-ray film. It is concluded that if the test specimens are thin, photographic papers

  4. Photographic and drafting techniques simplify method of producing engineering drawings

    Science.gov (United States)

    Provisor, H.

    1968-01-01

    Combination of photographic and drafting techniques has been developed to simplify the preparation of three dimensional and dimetric engineering drawings. Conventional photographs can be converted to line drawings by making copy negatives on high contrast film.

  5. Maximizing and stabilizing luminescence from halide perovskites with potassium passivation

    Science.gov (United States)

    Abdi-Jalebi, Mojtaba; Andaji-Garmaroudi, Zahra; Cacovich, Stefania; Stavrakas, Camille; Philippe, Bertrand; Richter, Johannes M.; Alsari, Mejd; Booker, Edward P.; Hutter, Eline M.; Pearson, Andrew J.; Lilliu, Samuele; Savenije, Tom J.; Rensmo, Håkan; Divitini, Giorgio; Ducati, Caterina; Friend, Richard H.; Stranks, Samuel D.

    2018-03-01

    Metal halide perovskites are of great interest for various high-performance optoelectronic applications. The ability to tune the perovskite bandgap continuously by modifying the chemical composition opens up applications for perovskites as coloured emitters, in building-integrated photovoltaics, and as components of tandem photovoltaics to increase the power conversion efficiency. Nevertheless, performance is limited by non-radiative losses, with luminescence yields in state-of-the-art perovskite solar cells still far from 100 per cent under standard solar illumination conditions. Furthermore, in mixed halide perovskite systems designed for continuous bandgap tunability (bandgaps of approximately 1.7 to 1.9 electronvolts), photoinduced ion segregation leads to bandgap instabilities. Here we demonstrate substantial mitigation of both non-radiative losses and photoinduced ion migration in perovskite films and interfaces by decorating the surfaces and grain boundaries with passivating potassium halide layers. We demonstrate external photoluminescence quantum yields of 66 per cent, which translate to internal yields that exceed 95 per cent. The high luminescence yields are achieved while maintaining high mobilities of more than 40 square centimetres per volt per second, providing the elusive combination of both high luminescence and excellent charge transport. When interfaced with electrodes in a solar cell device stack, the external luminescence yield—a quantity that must be maximized to obtain high efficiency—remains as high as 15 per cent, indicating very clean interfaces. We also demonstrate the inhibition of transient photoinduced ion-migration processes across a wide range of mixed halide perovskite bandgaps in materials that exhibit bandgap instabilities when unpassivated. We validate these results in fully operating solar cells. Our work represents an important advance in the construction of tunable metal halide perovskite films and interfaces that can

  6. A Photographer From Ankara: Osman Darcan

    Directory of Open Access Journals (Sweden)

    Gülseren Mungan Yavuztürk

    2015-12-01

    Full Text Available This work introduces Osman Darcan, an important name in the history of Ankara photography studios. Darcan followed in the footsteps of famous Austrian photographer Othmar Pferschy, whom he met in Istanbul, to go on to create his own valuable work. On leaving the Public Press Authority Photo Film Center, where he worked as a newsreel photographer and film operator, in 1943 he began taking photographs at the Tatbikat Theater at the Ankara State Conservatoire, where he continued as the photographer for the State Theater until the end of his life. At the same time, this master photographer took the pictures of a select coterie of Ankara’s leading individuals and well-known performers at a studio he opened on Anafartalar Caddesi. In both these roles, his photographs evoke admiration thanks to Darcan’s professional abilities and level of artistry.

  7. Improvements in or relating to a method of exposing and developing a photographic element

    International Nuclear Information System (INIS)

    Loprest, F.J.

    1981-01-01

    This patent specification claims on behalf of Gaf Corporation, Delaware, U.S.A., a method of exposing and developing a composite photographic reproduction material for use in industrial and medical radiography. The material carries an X-ray-sensitive silver halide emulsion with a considerably reduced amount of silver halide, in combination with a second light sensitive layer containing a light-sensitive composition selected from diazotype compositions which form azo dyes, vesicular compositions and photosensitive polymers. (U.K.)

  8. Alkali Halide Microstructured Optical Fiber for X-Ray Detection

    Science.gov (United States)

    DeHaven, S. L.; Wincheski, R. A.; Albin, S.

    2014-01-01

    Microstructured optical fibers containing alkali halide scintillation materials of CsI(Na), CsI(Tl), and NaI(Tl) are presented. The scintillation materials are grown inside the microstructured fibers using a modified Bridgman-Stockbarger technique. The x-ray photon counts of these fibers, with and without an aluminum film coating are compared to the output of a collimated CdTe solid state detector over an energy range from 10 to 40 keV. The photon count results show significant variations in the fiber output based on the materials. The alkali halide fiber output can exceed that of the CdTe detector, dependent upon photon counter efficiency and fiber configuration. The results and associated materials difference are discussed.

  9. Development and melt growth of novel scintillating halide crystals

    Science.gov (United States)

    Yoshikawa, Akira; Yokota, Yuui; Shoji, Yasuhiro; Kral, Robert; Kamada, Kei; Kurosawa, Shunsuke; Ohashi, Yuji; Arakawa, Mototaka; Chani, Valery I.; Kochurikhin, Vladimir V.; Yamaji, Akihiro; Andrey, Medvedev; Nikl, Martin

    2017-12-01

    Melt growth of scintillating halide crystals is reviewed. The vertical Bridgman growth technique is still considered as very popular method that enables production of relatively large and commercially attractive crystals. On the other hand, the micro-pulling-down method is preferable when fabrication of small samples, sufficient for preliminary characterization of their optical and/or scintillation performance, is required. Moreover, bulk crystal growth is also available using the micro-pulling-down furnace. The examples of growths of various halide crystals by industrially friendly melt growth techniques including Czochralski and edge-defined film-fed growth methods are also discussed. Finally, traveling molten zone growth that in some degree corresponds to horizontal zone melting is briefly overviewed.

  10. Development of Halide and Oxy-Halides for Isotopic Separations

    Energy Technology Data Exchange (ETDEWEB)

    Martin, Leigh R. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Johnson, Aaron T. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Pfeiffer, Jana [Idaho National Lab. (INL), Idaho Falls, ID (United States); Finck, Martha R. [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2014-10-01

    The goal of this project was to synthesize a volatile form of Np for introduction into mass spectrometers at INL. Volatile solids of the 5f elements are typically those of the halides (e.g. UF6), however fluorine is highly corrosive to the sensitive internal components of the mass separator, and the other volatile halides exist as several different stable isotopes in nature. However, iodide is both mono-isotopic and volatile, and as such presents an avenue for creation of a form of Np suitable for introduction into the mass separator. To accomplish this goal, the technical work in the project sought to establish a novel synthetic route for the conversion NpO2+ (dissolved in nitric acid) to NpI3 and NpI4.

  11. Black-and-white photographic chemistry: A reference

    Science.gov (United States)

    Walker, E. D. (Compiler)

    1986-01-01

    This work is intended as a reference of black-and-white photographic chemistry. Included is a basic history of the photographic processes and a complete description of all chemicals used, formulas for the development and fixation process, and associated formulas such as cleaners, hardeners, and toners. The work contains a complete glossary of photographic terms, a trouble-shooting section listing causes and effects regarding photographic film and papers, and various conversion charts.

  12. TRANSURANIC METAL HALIDES AND A PROCESS FOR THE PRODUCTION THEREOF

    Science.gov (United States)

    Fried, S.

    1951-03-20

    Halides of transuranic elements are prepared by contacting with aluminum and a halogen, or with an aluminum halide, a transuranic metal oxide, oxyhalide, halide, or mixture thereof at an elevated temperature.

  13. Experiencing Photographs Qua Photographs: What's So Special about Them?

    Directory of Open Access Journals (Sweden)

    Jiri Benovsky

    2013-01-01

    Full Text Available Merely rhetorically and answering in the negative, Kendall Walton has asked: "Isn't photography just another method people have of making pictures, one that merely uses different tools and materials; cameras, photosensitive paper, and darkroom equipment, rather than canvas, paint, and brushes? And don't the results differ only contingently and in degree, not fundamentally, from pictures of other kinds?" Contrary to Walton and others, I answer with a resounding "Yes" to Walton’s questions in this article. It is a widely shared view that photographs are somehow special and that they fundamentally differ from hand-made pictures such as paintings, both from a phenomenological point of view (in the way we experience them and an epistemic point of view (since they are supposed to have a different that is, greater, epistemic value from paintings that gives us a privileged access to the world. I almost reject the totality of these claims and, as a consequence, there remains little difference between photographs and paintings. As we shall see, “photographs are always partly paintings,” a claim that is true not only of retouched digital photographs but of all photographs, including traditional ones made using photosensitive film and development techniques.

  14. Environmental Effects on the Photophysics of Organic-Inorganic Halide Perovskites.

    Science.gov (United States)

    Galisteo-López, Juan F; Anaya, M; Calvo, M E; Míguez, H

    2015-06-18

    The photophysical properties of films of organic-inorganic lead halide perovskites under different ambient conditions are herein reported. We demonstrate that their luminescent properties are determined by the interplay between photoinduced activation and darkening processes, which strongly depend on the atmosphere surrounding the samples. We have isolated oxygen and moisture as the key elements in each process, activation and darkening, both of which involve the interaction with photogenerated carriers. These findings show that environmental factors play a key role in the performance of lead halide perovskites as efficient luminescent materials.

  15. Research Update: Physical and electrical characteristics of lead halide perovskites for solar cell applications

    Directory of Open Access Journals (Sweden)

    Simon A. Bretschneider

    2014-04-01

    Full Text Available The field of thin-film photovoltaics has been recently enriched by the introduction of lead halide perovskites as absorber materials, which allow low-cost synthesis of solar cells with efficiencies exceeding 16%. The exact impact of the perovskite crystal structure and composition on the optoelectronic properties of the material are not fully understood. Our progress report highlights the knowledge gained about lead halide perovskites with a focus on physical and optoelectronic properties. We discuss the crystal and band structure of perovskite materials currently implemented in solar cells and the impact of the crystal properties on ferroelectricity, ambipolarity, and the properties of excitons.

  16. A study on the localized corrosion of cobalt in bicarbonate solutions containing halide ions

    Energy Technology Data Exchange (ETDEWEB)

    Gallant, Danick [Departement de Biologie, Chimie et Sciences de la Sante, Universite du Quebec a Rimouski, 300, Allee des Ursulines, Rimouski, Que., G5L 3A1 (Canada); Departement de Chimie, Universite Laval, Quebec, Que., G1K 7P4 (Canada); Simard, Stephan [Departement de Biologie, Chimie et Sciences de la Sante, Universite du Quebec a Rimouski, 300, Allee des Ursulines, Rimouski, Que., G5L 3A1 (Canada)]. E-mail: stephan_simard@uqar.qc.ca

    2005-07-01

    The localized attack of cobalt in bicarbonate aqueous solutions containing halide ions was investigated using electrochemical techniques, scanning electron microscopy, UV-visible and Raman spectroscopies. Rotating disc and rotating ring-disc electrodes were used to determine the effect of bicarbonate concentration, solution pH, nature and concentration of the halide ions, convection and potential sweep rate on the corrosion processes. These parameters were found to play a key role on the localized attack induced by halide ions by influencing the production of a Co(HCO{sub 3}){sub 2} precipitate on the pit surface. Potentiostatically generated cobalt oxide films (CoO and Co{sub 3}O{sub 4}) were found to be efficient to reduce pitting corrosion of cobalt.

  17. Electrochemically reduced titanocene dichloride as a catalyst of reductive dehalogenation of organic halides

    International Nuclear Information System (INIS)

    Magdesieva, Tatiana V.; Graczyk, Magdalena; Vallat, Alain; Nikitin, Oleg M.; Demyanov, Petr I.; Butin, Kim P.; Vorotyntsev, Mikhail A.

    2006-01-01

    We have studied a reaction between the reduced form of titanocene dichloride (Cp 2 TiCl 2 ) and a group of organic halides: benzyl derivatives (4-X-C 6 H 4 CH 2 Cl, X = H, NO 2 , CH 3 ; 4-X-C 6 H 4 CH 2 Br, X = H, NO 2 , PhC(O); 4-X-C 6 H 4 CH 2 SCN, X = H, NO 2 ) as well as three aryl halides (4-NO 2 C 6 H 4 Hal, Hal = Cl, Br; 4-CH 3 O-C 6 H 4 Cl). It has been shown that the electrochemical reduction of Cp 2 TiCl 2 in the presence of these benzyl halides leads to a catalytic cycle resulting in the reductive dehalogenation of these organic substrates to yield mostly corresponding toluene derivatives as the main product. No dehalogenation has been observed for aryl derivatives. Based on electrochemical data and digital simulation, possible schemes of the catalytic process have been outlined. For non-substituted benzyl halides halogen atom abstraction is a key step. For the reaction of nitrobenzyl halides the complexation of Ti(III) species with the nitro group takes place, with the electron transfer from Ti(III) to this group (owing to its highest coefficient in LUMO of the nitro benzyl halide) followed by an intramolecular dissociative electron redistribution in the course of the heterolytic C-Hal bond cleavage. The results for reduced titanocene dichloride centers immobilized inside a polymer film showed that the catalytic reductive dehalogenation of the p-nitrobenzyl chloride does occur but with a low efficiency because of the partial deactivation of the film due to the blocking of the electron charge transport between the electrode and catalytic centers

  18. Variations in anthropogenic silver in a large Patagonian lake correlate with global shifts in photographic processing technology.

    Science.gov (United States)

    Juncos, Romina; Campbell, Linda; Arcagni, Marina; Daga, Romina; Rizzo, Andrea; Arribére, María; Ribeiro Guevara, Sergio

    2017-04-01

    At the beginning of the 21st century, digital imaging technology replaced the traditional silver-halide film photography which had implications in Ag contamination. Lake Nahuel Huapi is a popular Patagonia tourist destination impacted by municipal silver (Ag) contamination from photographic processing facilities since 1990's. Silver concentrations in a dated sediment core from the lake bottom showed a 10-fold increase above background levels in the second half of the 20th century, then a decrease. This trend corresponds well with published annual global photography industry demand for Ag, which clearly shows the evolution and replacement of the traditional silver-halide film photography by digital imaging technology. There were significant decreases in Ag concentrations in sediments, mussels and fish across the lake between 1998 and 2011. Lower trophic organisms had variable whole-body Ag concentrations, from 0.2-2.6 μg g -1 dry weight (DW) in plankton to 0.02-3.1 μg g -1 DW in benthic macroinvertebrates. Hepatic Ag concentrations in crayfish, mussels and predatory fish were significantly elevated relative to muscle which often have Ag concentrations below the detection limit (0.01-0.05 μg g -1 DW). Trophodynamic analyses using δ 15 N and whole-body invertebrate and muscle Ag concentrations indicated food web biodilution trends. High sedimentation rates in conjunction with the reduction of silver waste products discharged to the lake, as a result of the change to digital image processing technologies, are resulting in unplanned but welcome remediation of the Ag contamination in Lake Nahuel Huapi. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. Structure of polyvalent metal halide melts

    International Nuclear Information System (INIS)

    Tosi, M.P.

    1990-12-01

    A short review is given of recent progress in determining and understanding the structure of molten halide salts involving polyvalent metal ions. It covers the following three main topics: (i) melting mechanisms and types of liquid structure for pure polyvalent-metal chlorides; (ii) geometry and stability of local coordination for polyvalent metal ions in molten mixtures of their halides with alkali halides; and (iii) structure breaking and electron localization on addition of metal to the melt. (author). 28 refs, 3 figs, 1 tab

  20. Water-Induced Dimensionality Reduction in Metal-Halide Perovskites

    KAUST Repository

    Turedi, Bekir

    2018-03-30

    Metal-halide perovskite materials are highly attractive materials for optoelectronic applications. However, the instability of perovskite materials caused by moisture and heat-induced degradation impairs future prospects of using these materials. Here we employ water to directly transform films of the three-dimensional (3D) perovskite CsPbBr3 to stable two-dimensional (2D) perovskite-related CsPb2Br5. A sequential dissolution-recrystallization process governs this water induced transformation under PbBr2 rich condition. We find that these post-synthesized 2D perovskite-related material films exhibit excellent stability against humidity and high photoluminescence quantum yield. We believe that our results provide a new synthetic method to generate stable 2D perovskite-related materials that could be applicable for light emitting device applications.

  1. Halide based MBE of crystalline metals and oxides

    Energy Technology Data Exchange (ETDEWEB)

    Greenlee, Jordan D.; Calley, W. Laws; Henderson, Walter; Doolittle, W. Alan [Georgia Institute of Technology, School of Electrical and Computer Engineering, Atlanta, Georgia (United States)

    2012-02-15

    A halide based growth chemistry has been demonstrated which can deliver a range of transition metals using low to moderate effusion cell temperatures (30-700 C) even for high melting point metals. Previously, growth with transition metal species required difficult to control electron beam or impurity inducing metal organic sources. Both crystalline oxide and metal films exhibiting excellent crystal quality are grown using this halide-based growth chemistry. Films are grown using a plasma assisted Molecular Beam Epitaxy (MBE) system with metal-chloride precursors. Crystalline niobium, cobalt, iron, and nickel were grown using this chemistry but the technology can be generalized to almost any metal for which a chloride precursor is available. Additionally, the oxides LiNbO{sub 3} and LiNbO{sub 2} were grown with films exhibiting X-ray diffraction (XRD) rocking curve full-widths at half maximum of 150 and 190 arcseconds respectively. LiNbO{sub 2} films demonstrate a memristive response due to the rapid movement of lithium in the layered crystal structure. The rapid movement of lithium ions in LiNbO{sub 2} memristors is characterized using impedance spectroscopy measurements. The impedance spectroscopy measurements suggest an ionic current of.1 mA for a small drive voltage of 5 mV AC or equivalently an ionic current density of {proportional_to}87 A/cm{sup 2}. This high ionic current density coupled with low charge transfer resistance of {proportional_to}16.5 {omega} and a high relaxation frequency (6.6 MHz) makes this single crystal material appealing for battery applications in addition to memristors. (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  2. Glacier Photograph Collection

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Glacier Photograph Collection is a database of photographs of glaciers from around the world, some dating back to the mid-1850's, that provide an historical...

  3. Fullerenes doped with metal halides

    International Nuclear Information System (INIS)

    Martin, T.P.; Heinebrodt, M.; Naeher, U.; Goehlich, H.; Lange, T.; Schaber, H.

    1993-01-01

    The cage-like structure of fullerenes is a challenge to every experimental to put something inside - to dope the fullerenes. In fact, the research team that first identified C 60 as a football-like molecule quickly succeeded in trapping metal atoms inside and in shrinking the cage around this atom by photofragmentation. In this paper we report the results of ''shrink-wrapping'' the fullerenes around metal halide molecules. Of special interest is the critical size (the minimum number of carbon atoms) that can still enclose the dopant. A rough model for the space available inside a carbon cage gives good agreement with the measured shrinking limits. (author). 8 refs, 6 figs

  4. Transformation of Sintered CsPbBr3 Nanocrystals to Cubic CsPbI3 and Gradient CsPbBrxI3-x through Halide Exchange.

    Science.gov (United States)

    Hoffman, Jacob B; Schleper, A Lennart; Kamat, Prashant V

    2016-07-13

    All-inorganic cesium lead halide (CsPbX3, X = Br(-), I(-)) perovskites could potentially provide comparable photovoltaic performance with enhanced stability compared to organic-inorganic lead halide species. However, small-bandgap cubic CsPbI3 has been difficult to study due to challenges forming CsPbI3 in the cubic phase. Here, a low-temperature procedure to form cubic CsPbI3 has been developed through a halide exchange reaction using films of sintered CsPbBr3 nanocrystals. The reaction was found to be strongly dependent upon temperature, featuring an Arrhenius relationship. Additionally, film thickness played a significant role in determining internal film structure at intermediate reaction times. Thin films (50 nm) showed only a small distribution of CsPbBrxI3-x species, while thicker films (350 nm) exhibited much broader distributions. Furthermore, internal film structure was ordered, featuring a compositional gradient within film. Transient absorption spectroscopy showed the influence of halide exchange on the excited state of the material. In thicker films, charge carriers were rapidly transferred to iodide-rich regions near the film surface within the first several picoseconds after excitation. This ultrafast vectorial charge-transfer process illustrates the potential of utilizing compositional gradients to direct charge flow in perovskite-based photovoltaics.

  5. Methods for producing single crystal mixed halide perovskites

    Science.gov (United States)

    Zhu, Kai; Zhao, Yixin

    2017-07-11

    An aspect of the present invention is a method that includes contacting a metal halide and a first alkylammonium halide in a solvent to form a solution and maintaining the solution at a first temperature, resulting in the formation of at least one alkylammonium halide perovskite crystal, where the metal halide includes a first halogen and a metal, the first alkylammonium halide includes the first halogen, the at least one alkylammonium halide perovskite crystal includes the metal and the first halogen, and the first temperature is above about 21.degree. C.

  6. Silver-Doping Effects and Photostructural Transformation in Evaporated AS2S3 Thin Films.

    Science.gov (United States)

    1982-02-16

    of evaporated silver halide films. The details of the preparation of evaporated films of silver halides are reported by Junod at. al. (41 ) The...1980). 40. M.S. Chang, N.D. Hwang, J.T. Chen, Extended Abstr. Electrochem. Soc., 80-1, 692, (1980). 41. P. Junod , N. MHediger, B. Kilchoy. R. Steiger

  7. Chain-length dependent para-phenyelene film- and needle-growth on dielectrics

    DEFF Research Database (Denmark)

    Balzer, Frank; Rubahn, Horst-Günter

    2004-01-01

    Surface unit cells of vacuum grown ultrathin films of blue-light emitting para-phenylene oligomers on alkali halides and on muscovite mica have been determined using low energy electron diffraction. Both, films from upright and from laying molecules are grown on alkali halide (1 0 0) and mica (0 ...

  8. Post-process intensification of photographic silver images, using radioactive compounds

    International Nuclear Information System (INIS)

    1979-01-01

    A method of post-process intensification of silver images on a developed and fixed photographic film or plate is described, comprising the steps of (a) converting silver of the developed film or plate to a radioactive compound by contracting the film or plate with an aqueous alkaline solution of an organo-S 35 compound which reacts selectively with silver in a photographic film or plate; (b) placing the film or plate treated in step (a) in direct contact with a receiver film which is sensitive to beta radiation whereby the receiver film is exposed by radiation from the radioactive compound; and (c) developing and fixing the resulting intensified receiver film. (author)

  9. Thermochromic halide perovskite solar cells

    Science.gov (United States)

    Lin, Jia; Lai, Minliang; Dou, Letian; Kley, Christopher S.; Chen, Hong; Peng, Fei; Sun, Junliang; Lu, Dylan; Hawks, Steven A.; Xie, Chenlu; Cui, Fan; Alivisatos, A. Paul; Limmer, David T.; Yang, Peidong

    2018-03-01

    Smart photovoltaic windows represent a promising green technology featuring tunable transparency and electrical power generation under external stimuli to control the light transmission and manage the solar energy. Here, we demonstrate a thermochromic solar cell for smart photovoltaic window applications utilizing the structural phase transitions in inorganic halide perovskite caesium lead iodide/bromide. The solar cells undergo thermally-driven, moisture-mediated reversible transitions between a transparent non-perovskite phase (81.7% visible transparency) with low power output and a deeply coloured perovskite phase (35.4% visible transparency) with high power output. The inorganic perovskites exhibit tunable colours and transparencies, a peak device efficiency above 7%, and a phase transition temperature as low as 105 °C. We demonstrate excellent device stability over repeated phase transition cycles without colour fade or performance degradation. The photovoltaic windows showing both photoactivity and thermochromic features represent key stepping-stones for integration with buildings, automobiles, information displays, and potentially many other technologies.

  10. Thermochromic halide perovskite solar cells.

    Science.gov (United States)

    Lin, Jia; Lai, Minliang; Dou, Letian; Kley, Christopher S; Chen, Hong; Peng, Fei; Sun, Junliang; Lu, Dylan; Hawks, Steven A; Xie, Chenlu; Cui, Fan; Alivisatos, A Paul; Limmer, David T; Yang, Peidong

    2018-03-01

    Smart photovoltaic windows represent a promising green technology featuring tunable transparency and electrical power generation under external stimuli to control the light transmission and manage the solar energy. Here, we demonstrate a thermochromic solar cell for smart photovoltaic window applications utilizing the structural phase transitions in inorganic halide perovskite caesium lead iodide/bromide. The solar cells undergo thermally-driven, moisture-mediated reversible transitions between a transparent non-perovskite phase (81.7% visible transparency) with low power output and a deeply coloured perovskite phase (35.4% visible transparency) with high power output. The inorganic perovskites exhibit tunable colours and transparencies, a peak device efficiency above 7%, and a phase transition temperature as low as 105 °C. We demonstrate excellent device stability over repeated phase transition cycles without colour fade or performance degradation. The photovoltaic windows showing both photoactivity and thermochromic features represent key stepping-stones for integration with buildings, automobiles, information displays, and potentially many other technologies.

  11. Copper(I) Thiocyanate (CuSCN) Hole-Transport Layers Processed from Aqueous Precursor Solutions and Their Application in Thin-Film Transistors and Highly Efficient Organic and Organometal Halide Perovskite Solar Cells

    KAUST Repository

    Wijeyasinghe, Nilushi; Regoutz, Anna; Eisner, Flurin; Du, Tian; Tsetseris, Leonidas; Lin, Yen-Hung; Faber, Hendrik; Pattanasattayavong, Pichaya; Li, Jinhua; Yan, Feng; McLachlan, Martyn A.; Payne, David J.; Heeney, Martin; Anthopoulos, Thomas D.

    2017-01-01

    spectra agree with first-principles calculations. Study of the hole-transport properties using field-effect transistor measurements reveals that the aqueous-processed CuSCN layers exhibit a fivefold higher hole mobility than films processed from diethyl

  12. Effect of halide-mixing on the switching behaviors of organic-inorganic hybrid perovskite memory

    Science.gov (United States)

    Hwang, Bohee; Gu, Chungwan; Lee, Donghwa; Lee, Jang-Sik

    2017-03-01

    Mixed halide perovskite materials are actively researched for solar cells with high efficiency. Their hysteresis which originates from the movement of defects make perovskite a candidate for resistive switching memory devices. We demonstrate the resistive switching device based on mixed-halide organic-inorganic hybrid perovskite CH3NH3PbI3-xBrx (x = 0, 1, 2, 3). Solvent engineering is used to deposit the homogeneous CH3NH3PbI3-xBrx layer on the indium-tin oxide-coated glass substrates. The memory device based on CH3NH3PbI3-xBrx exhibits write endurance and long retention, which indicate reproducible and reliable memory properties. According to the increase in Br contents in CH3NH3PbI3-xBrx the set electric field required to make the device from low resistance state to high resistance state decreases. This result is in accord with the theoretical calculation of migration barriers, that is the barrier to ionic migration in perovskites is found to be lower for Br- (0.23 eV) than for I- (0.29-0.30 eV). The resistive switching may be the result of halide vacancy defects and formation of conductive filaments under electric field in the mixed perovskite layer. It is observed that enhancement in operating voltage can be achieved by controlling the halide contents in the film.

  13. Evaluating stream trout habitat on large-scale aerial color photographs

    Science.gov (United States)

    Wallace J. Greentree; Robert C. Aldrich

    1976-01-01

    Large-scale aerial color photographs were used to evaluate trout habitat by studying stream and streambank conditions. Ninety-two percent of these conditions could be identified correctly on the color photographs. Color photographs taken 1 year apart showed that rehabilitation efforts resulted in stream vegetation changes. Water depth was correlated with film density:...

  14. Halide-Dependent Electronic Structure of Organolead Perovskite Materials

    KAUST Repository

    Buin, Andrei; Comin, Riccardo; Xu, Jixian; Ip, Alexander H.; Sargent, Edward H.

    2015-01-01

    -based perovskites, in line with recent experimental data. As a result, the optimal growth conditions are also different for the distinct halide perovskites: growth should be halide-rich for Br and Cl, and halide-poor for I-based perovskites. We discuss stability

  15. Computational screening of mixed metal halide ammines

    DEFF Research Database (Denmark)

    Jensen, Peter Bjerre; Lysgaard, Steen; Quaade, Ulrich

    2013-01-01

    Metal halide ammines, e.g. Mg(NH3)6Cl2 and Sr(NH3)8Cl2, can reversibly store ammonia, with high volumetric hydrogen storage capacities. The storage in the halide ammines is very safe, and the salts are therefore highly relevant as a carbon-free energy carrier in future transportation infrastructure...... selection. The GA is evolving from an initial (random) population and selecting those with highest fitness, a function based on e.g. stability, release temperature and storage capacity. The search space includes all alkaline, alkaline earth, 3d and 4d metals and the four lightest halides. In total...... the search spaces consists of millions combinations, which makes a GA ideal, to reduce the number of necessary calculations. We are screening for a one step release from either a hexa or octa ammine, and we have found promising candidates, which will be further investigated ? both computationally...

  16. Muonium centers in the alkali halides

    International Nuclear Information System (INIS)

    Baumeler, H.; Kiefl, R.F.; Keller, H.; Kuendig, W.; Odermatt, W.; Patterson, B.D.; Schneider, J.W.; Savic, I.M.

    1986-01-01

    Muonium centers (Mu) in single crystals and powdered alkali halides have been studied using the high-timing-resolution transverse field μSR technique. Mu has been observed and its hyperfine parameter (HF) determined in every alkali halide. For the rocksalt alkali halides, the HF parameter A μ shows a systematic dependence on the host lattice constant. A comparison of the Mu HF parameter with hydrogen ESR data suggests that the Mu center is the muonic analogue of the interstitial hydrogen H i 0 -center. The rate of Mu diffusion can be deduced from the motional narrowing of the nuclear hyperfine interaction. KBr shows two different Mu states, a low-temperature Mu I -state and a high-temperature Mu II -state. (orig.)

  17. The use of film badges for personnel monitoring

    International Nuclear Information System (INIS)

    Ehrlich, M.

    1962-01-01

    Photographic film is fairly inexpensive and durable and as a result of irradiation its radiosensitive components undergo relatively permanent changes. With proper calibration the optical density of the development and fixed photographic film can be related to radiation exposure. Personnel monitoring with photographic film is the method of choice in many laboratories, and this manual gives guidelines for the use of photographic film in personnel dosimetry.

  18. Dose-response of photographic emulsions under gamma irradiation

    International Nuclear Information System (INIS)

    Tran Dai Nghiep; Do Thi Nguyet Minh; Le Van Vinh

    2003-01-01

    Photographic emulsion is irradiated under gamma rays irradiation of 137 Cs in the IAEA/WHO secondary standard dosimetry laboratory. Dose-response of the film is established. The sensitivity of the film is determined. The dose-rate effect is studied. (author)

  19. The calibration of photographic and spectroscopic films: 1: A microscopic analysis of IIaO films. 2: The effects of agitation and soaking on IIaO films. 3: The effects of electric field on IIaO films. 4: The effects of X-ray radiation on IIaO films

    Science.gov (United States)

    Hammond, E. C., Jr.; Peters, K.; Boone, K.

    1978-01-01

    The grain structure of the emulsion using both reflected and transmission light was examined along with the effects of soaking. The effect of a static charge by a Tesla-coil, and the effects of airport equipment, and dental X-rays on the film were also analyzed.

  20. A Relational Ecology of Photographic Practices

    Directory of Open Access Journals (Sweden)

    Jacqui Knight

    2017-11-01

    Full Text Available This paper proposes a relational history of media artifacts, which decentralizes the dominance of the photographer or filmmaker as the absolute author of the work. It adds an alternative account to understanding the creative process and the subsequent study of media forms by discussing film and photographic practices as the reciprocal affective relationship between the maker, their intentions, materials, technologies, non-human agents and the environment. By reorganizing the anthropocentrism of art historical narratives, which typically exclude corporeality and materiality as drivers of human history, we are able to discuss the complex dynamic meshwork of determinants that bring photographic artifacts into existence: the lived, animate, vital materialism at once emergent and mixing of different causalities and temporalities.

  1. Effects of Annealing Conditions on Mixed Lead Halide Perovskite Solar Cells and Their Thermal Stability Investigation.

    Science.gov (United States)

    Yang, Haifeng; Zhang, Jincheng; Zhang, Chunfu; Chang, Jingjing; Lin, Zhenhua; Chen, Dazheng; Xi, He; Hao, Yue

    2017-07-21

    In this work, efficient mixed organic cation and mixed halide (MA 0.7 FA 0.3 Pb(I 0.9 Br 0.1 )₃) perovskite solar cells are demonstrated by optimizing annealing conditions. AFM, XRD and PL measurements show that there is a better perovskite film quality for the annealing condition at 100 °C for 30 min. The corresponding device exhibits an optimized PCE of 16.76% with V OC of 1.02 V, J SC of 21.55 mA/cm² and FF of 76.27%. More importantly, the mixed lead halide perovskite MA 0.7 FA 0.3 Pb(I 0.9 Br 0.1 )₃ can significantly increase the thermal stability of perovskite film. After being heated at 80 °C for 24 h, the PCE of the MA 0.7 FA 0.3 Pb(I 0.9 Br 0.1 )₃ device still remains at 70.00% of its initial value, which is much better than the control MAPbI₃ device, where only 46.50% of its initial value could be preserved. We also successfully fabricated high-performance flexible mixed lead halide perovskite solar cells based on PEN substrates.

  2. Reactivity of halide and pseudohalide ligands

    International Nuclear Information System (INIS)

    Kukushkin, Yu.N.

    1987-01-01

    Reactivity of halide and pseudohalide (cyanide, azide, thiocyanate, cyanate) ligands tending to form bridge bonds in transition metal (Re, Mo, W) complexes is considered. Complexes where transition metal salts are ligands of other, complex-forming ion, are described. Transformation of innerspheric pseudohalide ligands is an important way of directed synthesis of these metal coordination compounds

  3. Formation of structured nanophases in halide crystals

    Czech Academy of Sciences Publication Activity Database

    Kulveit, Jan; Demo, Pavel; Polák, Karel; Sveshnikov, Alexey; Kožíšek, Zdeněk

    2013-01-01

    Roč. 5, č. 6 (2013), s. 561-564 ISSN 2164-6627 R&D Projects: GA ČR GAP108/12/0891 Institutional support: RVO:68378271 Keywords : halide crystals * nucleation Subject RIV: BM - Solid Matter Physics ; Magnetism http://www.aspbs.com/asem.html#v5n6

  4. Complexes of alkylphenols with aluminium halides

    International Nuclear Information System (INIS)

    Golounin, A.V.

    1997-01-01

    Interaction of aluminium halides with alkylphenols is studied through the NMR method. The peculiarity of complex formation of pentamethylphenol with AlI 3 is revealed. By AlI 3 action on the pentamethylphenol the complexes are formed both of keto- and oxy form [ru

  5. luminescence in coloured alkali halide crystals

    Indian Academy of Sciences (India)

    have studied the effect of annealing in chlorine gas on the ML of X-rayed KCl crystals. ..... high temperature because of the thermal bleaching of the coloration in alkali halide ..... [31] J Hawkins, Ph.D. Thesis (University of Reading, 1976).

  6. Monocrystalline halide perovskite nanostructures for optoelectronic applications

    NARCIS (Netherlands)

    Khoram, P.

    2018-01-01

    Halide perovskites are a promising class of materials for incorporation in optoelectronics with higher efficiency and lower cost. The solution processability of these materials provides unique opportunities for simple nanostructure fabrication. In the first half of the thesis (chapter 2 and 3) we

  7. Photography: enhancing sensitivity by silver-halide crystal doping

    International Nuclear Information System (INIS)

    Belloni, Jacqueline

    2003-01-01

    The physical chemistry of the silver photography processes, exposure, development and fixing, is briefly summarized. The mechanism of the autocatalytic development by the developer of the clusters produced in silver bromide crystals during the exposure which is controlled by the critical nuclearity of these clusters was understood from pulse radiolysis studies. The effective quantum yield PHI eff of photoinduced silver cluster formation in silver halide microcrystals is usually much lower than the photoionization theoretical limit PHI theor =1 electron-hole pair per photon absorbed, owing to a subsequent very fast intra-crystal recombination of a part of the electron-hole pairs. In order to inhibit this recombination and favor the silver reduction by photo-electrons, the AgX crystals were doped with the formate HCO 2 - as a specific hole scavenger. First, the dopant scavenges the photoinduced hole, thus enhancing the electron escape from the pair recombination. Second, the CO 2 ·- radical so formed transfers an electron to another silver cation, so that the PHI eff limit may be of 2Ag 0 per photon. This Photoinduced Bielectronic Transfer mechanism is strictly proportional to the light quanta absorbed and induces an exceptional efficiency for enhancing the radio- or photographic sensitivity insofar as it totally suppresses the electron-hole recombination

  8. Laser-Induced Breakdown Spectroscopy of Cinematographic Film

    Science.gov (United States)

    Oujja, M.; Abrusci, C.; Gaspard, S.; Rebollar, E.; Amo, A. del; Catalina, F.; Castillejo, M.

    Laser-induced breakdown spectroscopy (LIBS) was used to characterize the composition of black-and-white, silver-gelatine photographic films. LIB spectra of samples and reference gelatine (of various gel strengths, Bloom values 225 and 75 and crosslinking degrees) were acquired in vacuum by excitation at 266 nm. The elemental composition of the gelatine used in the upper protective layer and in the underlying emulsion is revealed by the stratigraphic analysis carried out by delivering successive pulses on the same spot of the sample. Silver (Ag) lines from the light-sensitive silver halide salts are accompanied by iron, lead and chrome lines. Fe and Pb are constituents of film developers and Cr is included in the hardening agent. The results demonstrate the analytical capacity of LIBS for study and classification of different gelatine types and the sensitivity of the technique to minor changes in gelatine composition. In addition LIBS analysis allows extracting important information on the chemicals used as developers and hardeners of archival cinematographic films.

  9. Electrochemically reduced titanocene dichloride as a catalyst of reductive dehalogenation of organic halides

    Energy Technology Data Exchange (ETDEWEB)

    Magdesieva, Tatiana V. [Department Chemistry, M.V. Lomonosov Moscow State University, Moscow 119992 (Russian Federation)]. E-mail: tvm@org.chem.msu.ru; Graczyk, Magdalena [LSEO-UMR 5188 CNRS, Universite de Bourgogne, Dijon (France); Vallat, Alain [LSEO-UMR 5188 CNRS, Universite de Bourgogne, Dijon (France); Nikitin, Oleg M. [Department Chemistry, M.V. Lomonosov Moscow State University, Moscow 119992 (Russian Federation); Demyanov, Petr I. [Department Chemistry, M.V. Lomonosov Moscow State University, Moscow 119992 (Russian Federation); Butin, Kim P. [Department Chemistry, M.V. Lomonosov Moscow State University, Moscow 119992 (Russian Federation); Vorotyntsev, Mikhail A. [LSEO-UMR 5188 CNRS, Universite de Bourgogne, Dijon (France)]. E-mail: MV@u-bourgogne.fr

    2006-11-12

    We have studied a reaction between the reduced form of titanocene dichloride (Cp{sub 2}TiCl{sub 2}) and a group of organic halides: benzyl derivatives (4-X-C{sub 6}H{sub 4}CH{sub 2}Cl, X = H, NO{sub 2}, CH{sub 3}; 4-X-C{sub 6}H{sub 4}CH{sub 2}Br, X = H, NO{sub 2}, PhC(O); 4-X-C{sub 6}H{sub 4}CH{sub 2}SCN, X = H, NO{sub 2}) as well as three aryl halides (4-NO{sub 2}C{sub 6}H{sub 4}Hal, Hal = Cl, Br; 4-CH{sub 3}O-C{sub 6}H{sub 4}Cl). It has been shown that the electrochemical reduction of Cp{sub 2}TiCl{sub 2} in the presence of these benzyl halides leads to a catalytic cycle resulting in the reductive dehalogenation of these organic substrates to yield mostly corresponding toluene derivatives as the main product. No dehalogenation has been observed for aryl derivatives. Based on electrochemical data and digital simulation, possible schemes of the catalytic process have been outlined. For non-substituted benzyl halides halogen atom abstraction is a key step. For the reaction of nitrobenzyl halides the complexation of Ti(III) species with the nitro group takes place, with the electron transfer from Ti(III) to this group (owing to its highest coefficient in LUMO of the nitro benzyl halide) followed by an intramolecular dissociative electron redistribution in the course of the heterolytic C-Hal bond cleavage. The results for reduced titanocene dichloride centers immobilized inside a polymer film showed that the catalytic reductive dehalogenation of the p-nitrobenzyl chloride does occur but with a low efficiency because of the partial deactivation of the film due to the blocking of the electron charge transport between the electrode and catalytic centers.

  10. Perfection of the individual photographic emulsion dosimeter

    International Nuclear Information System (INIS)

    Soudain, G.

    1960-01-01

    A photographic dosimeter making possible the measurement of γ radiation doses of from 10 mr up to 800 r by means of 3 emulsion bands of varying sensitivity stuck to the same support is described. The dosimeter has also a zone for marking and a test film insensitive to radiation. This requires a photometric measurement by diffuse reflection an d makes it possible to measure doses with an accuracy of 20 per cent. (author) [fr

  11. Apollo Lunar Sample Photographs: Digitizing the Moon Rock Collection

    Science.gov (United States)

    Lofgren, Gary E.; Todd, Nancy S.; Runco, S. K.; Stefanov, W. L.

    2011-01-01

    The Acquisition and Curation Office at JSC has undertaken a 4-year data restoration project effort for the lunar science community funded by the LASER program (Lunar Advanced Science and Exploration Research) to digitize photographs of the Apollo lunar rock samples and create high resolution digital images. These sample photographs are not easily accessible outside of JSC, and currently exist only on degradable film in the Curation Data Storage Facility

  12. Morphology-Controlled Synthesis of Organometal Halide Perovskite Inverse Opals.

    Science.gov (United States)

    Chen, Kun; Tüysüz, Harun

    2015-11-09

    The booming development of organometal halide perovskites in recent years has prompted the exploration of morphology-control strategies to improve their performance in photovoltaic, photonic, and optoelectronic applications. However, the preparation of organometal halide perovskites with high hierarchical architecture is still highly challenging and a general morphology-control method for various organometal halide perovskites has not been achieved. A mild and scalable method to prepare organometal halide perovskites in inverse opal morphology is presented that uses a polystyrene-based artificial opal as hard template. Our method is flexible and compatible with different halides and organic ammonium compositions. Thus, the perovskite inverse opal maintains the advantage of straightforward structure and band gap engineering. Furthermore, optoelectronic investigations reveal that morphology exerted influence on the conducting nature of organometal halide perovskites. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Physicochemical properties of mixed phosphorus halides

    International Nuclear Information System (INIS)

    Sladkov, I.B.; Tugarinova, N.S.

    1996-01-01

    Certain physicochemical properties (thermodynamic characteristics at boiling point, critical constants, density of liquid on the saturation line) of mixed phosphorus halides (PI 3 , PI 2 F, PIF 2 , PI 2 Cl, PICl 2 , PI 1 Br, PIBr 2 , PIClF, PIBrCl, etc.) are determined by means of approximate methods. Reliability of the results obtained is confirmed by comparison of calculated and experimental data for phosphorus compounds of the same type. 7 refs., 3 figs., 4 tabs

  14. Unraveling halide hydration: A high dilution approach.

    Science.gov (United States)

    Migliorati, Valentina; Sessa, Francesco; Aquilanti, Giuliana; D'Angelo, Paola

    2014-07-28

    The hydration properties of halide aqua ions have been investigated combining classical Molecular Dynamics (MD) with Extended X-ray Absorption Fine Structure (EXAFS) spectroscopy. Three halide-water interaction potentials recently developed [M. M. Reif and P. H. Hünenberger, J. Chem. Phys. 134, 144104 (2011)], along with three plausible choices for the value of the absolute hydration free energy of the proton (ΔG [minus sign in circle symbol]hyd[H+]), have been checked for their capability to properly describe the structural properties of halide aqueous solutions, by comparing the MD structural results with EXAFS experimental data. A very good agreement between theory and experiment has been obtained with one parameter set, namely LE, thus strengthening preliminary evidences for a ΔG [minus sign in circle symbol]hyd[H] value of -1100 kJ mol(-1) [M. M. Reif and P. H. Hünenberger, J. Chem. Phys. 134, 144104 (2011)]. The Cl(-), Br(-), and I(-) ions have been found to form an unstructured and disordered first hydration shell in aqueous solution, with a broad distribution of instantaneous coordination numbers. Conversely, the F(-) ion shows more ordered and defined first solvation shell, with only two statistically relevant coordination geometries (six and sevenfold complexes). Our thorough investigation on the effect of halide ions on the microscopic structure of water highlights that the perturbation induced by the Cl(-), Br(-), and I(-) ions does not extend beyond the ion first hydration shell, and the structure of water in the F(-) second shell is also substantially unaffected by the ion.

  15. Thermomechanical measurements of lead halide single crystals

    Czech Academy of Sciences Publication Activity Database

    Nitsch, Karel; Rodová, Miroslava

    2002-01-01

    Roč. 234, č. 2 (2002), s. 701-709 ISSN 0370-1972 R&D Projects: GA AV ČR IAA2010926 Institutional research plan: CEZ:AV0Z1010914 Keywords : PbX 2 (X=Cl, Br, I) * coefficients of linear thermal expansion * polymorphism in lead halides Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.930, year: 2002

  16. Electrochemistry of plutonium in molten halides

    International Nuclear Information System (INIS)

    McCurry, L.E.; Moy, G.M.M.; Bowersox, D.F.

    1987-01-01

    The electrochemistry of plutonium in molten halides is of technological importance as a method of purification of plutonium. Previous authors have reported that plutonium can be purified by electrorefining impure plutonium in various molten haldies. Work to eluciate the mechanism of the plutonium reduction in molten halides has been limited to a chronopotentiometric study in LiCl-KCl. Potentiometric studies have been carried out to determine the standard reduction potential for the plutonium (III) couple in various molten alkali metal halides. Initial cyclic voltammetric experiments were performed in molten KCL at 1100 K. A silver/silver chloride (10 mole %) in equimolar NaCl-KCl was used as a reference electrode. Working and counter electrodes were tungsten. The cell components and melt were contained in a quartz crucible. Background cyclic voltammograms of the KCl melt at the tungsten electrode showed no evidence of electroactive impurities in the melt. Plutonium was added to the melt as PuCl/sub 3/, which was prepared by chlorination of the oxide. At low concentrations of PuCl/sub 3/ in the melt (0.01-0.03 molar), no reduction wave due to the reduction of Pu(III) was observed in the voltammograms up to the potassium reduction limit of the melt. However on scan reversal after scanning into the potassium reduction limit a new oxidation wave was observed

  17. Complexes in polyvalent metal - Alkali halide melts

    International Nuclear Information System (INIS)

    Akdeniz, Z.; Tosi, M.P.

    1991-03-01

    Experimental evidence is available in the literature on the local coordination of divalent and trivalent metal ions by halogens in some 140 liquid mixtures of their halides with alkali halides. After brief reference to classification criteria for main types of local coordination, we focus on statistical mechanical models that we are developing for Al-alkali halide mixtures. Specifically, we discuss theoretically the equilibrium between (AlF 6 ) 3- and (AlF 4 ) - complexes in mixtures of AlF 3 and NaF as a function of composition in the NaF-rich region, the effect of the alkali counterion on this equilibrium, the possible role of (AlF 5 ) 2- as an intermediate species in molten cryolite, and the origin of the different complexing behaviours of Al-alkali fluorides and chlorides. We also present a theoretical scenario for processes of structure breaking and electron localization in molten cryolite under addition of sodium metal. (author). 26 refs, 2 tabs

  18. Investigation of surface halide modification of nitrile butadiene rubber

    Science.gov (United States)

    Sukhareva, K. V.; Mikhailov, I. A.; Andriasyan, Yu O.; Mastalygina, E. E.; Popov, A. A.

    2017-12-01

    The investigation is devoted to the novel technology of surface halide modification of rubber samples based on nitrile butadiene rubber (NBR). 1,1,2-trifluoro-1,2,2-trichlorethane was used as halide modifier. The developed technology is characterized by production stages reduction to one by means of treating the rubber compound with a halide modifier. The surface halide modification of compounds based on nitrile butadiene rubber (NBR) was determined to result in increase of resistance to thermal oxidation and aggressive media. The conducted research revealed the influence of modification time on chemical resistance and physical-mechanical properties of rubbers under investigation.

  19. Lanthanide doped strontium-barium cesium halide scintillators

    Science.gov (United States)

    Bizarri, Gregory; Bourret-Courchesne, Edith; Derenzo, Stephen E.; Borade, Ramesh B.; Gundiah, Gautam; Yan, Zewu; Hanrahan, Stephen M.; Chaudhry, Anurag; Canning, Andrew

    2015-06-09

    The present invention provides for a composition comprising an inorganic scintillator comprising an optionally lanthanide-doped strontium-barium, optionally cesium, halide, useful for detecting nuclear material.

  20. Electro photographic materials

    International Nuclear Information System (INIS)

    Buzdugan, A.; Andries, A.; Iovu, M.

    2000-01-01

    The invention relates to the creation of electro photographic materials . The invention allows to extend the material photosensitivity into the infrared range of the spectrum. An electro photographic materials contains an electro conducting base, including a dielectric base 1, for example glass, an electro conducting layer 2, for example of Al, Ni, Cr, an injecting layer 3, consisting of amorphous indium phosphide, a vitreous layer 4 of the arsenic sulphide - antimony sulphide system and a transporting layer 5 of the arsenic sulphide or arsenic selenide

  1. Studies on radiation-sensitive nonsilver halide materials, (1)

    International Nuclear Information System (INIS)

    Komizu, Hideo; Honda, Koichi; Yabe, Akira; Kawasaki, Masami; Fujii, Etsuo

    1978-01-01

    In order to discover new radiation-sensitive nonsilver halide materials, the coloration based on the formation of Stenhouse salts was studied in the following three systems: (a) furfural-amine/HCl aq/methanol solution, (b) furfural-amine/polyhalogenide/PMMA matrix, (c) furfural-amine/PVC matrix. Firstly, forty-five aromatic amines were surveyed to find out the amines suitable for the color precursors (reactant from furfural and amine) in the system (a). As a result, the five amines, which gave the precursors in good yields by the reaction with furfural, were selected: m-nitroaniline, N-methylaniline, m-methyl-N-methylaniline, aniline, and o-methoxyaniline. Secondly, the coloration induced by electron beam bombardment was studied in the systems (b) and (c) containing the color precursors (the reactants from these amines and furfural). Although the PMMA films containing the color precursors and polyhalogenides were sensitive to electron beam, they were not stable when standing under daylight at room temperature. The PVC films containing the color precursors were very stable and colored to reddish yellow (lambda sub(max) 498 - 545 nm) by electron beam bombardment. The PVC film containing N-methylaniline-furfural was the most sensitive and the increase in absorbance at 498 nm was 0.78 by electron beam bombardment of 60 kV - 7.5 x 10 -7 C/cm 2 . A good linear relationship existed between the degree of coloration and the amounts of electron beam bombardment in the range from 0 to 10 -6 C/cm 2 . (author)

  2. Nucleation and Crystal Growth of Organic-Inorganic Lead Halide Perovskites under Different Relative Humidity.

    Science.gov (United States)

    Gao, Hao; Bao, Chunxiong; Li, Faming; Yu, Tao; Yang, Jie; Zhu, Weidong; Zhou, Xiaoxin; Fu, Gao; Zou, Zhigang

    2015-05-06

    Organic-inorganic lead halide perovskite compounds are very promising materials for high-efficiency perovskite solar cells. But how to fabricate high-quality perovksite films under controlled humidity conditions is still an important issue due to their sensitivity to moisture. In this study, we investigated the influence of ambient humidity on crystallization and surface morphology of one-step spin-coated perovskite films, as well as the performance of solar cells based on these perovskite films. On the basis of experimental analyses and thin film growth theory, we conclude that the influence of ambient humidity on nucleation at spin-coating stage is quite different from that on crystal growth at annealing stage. At the spin-coating stage, high nucleation density induced by high supersaturation prefers to appear under anhydrous circumstances, resulting in layer growth and high coverage of perovskite films. But at the annealing stage, the modest supersaturation benefits formation of perovskite films with good crystallinity. The films spin-coated under low relative humidity (RH) followed by annealing under high RH show an increase of crystallinity and improved performance of devices. Therefore, a mechanism of fast nucleation followed by modest crystal growth (high supersaturation at spin-coating stage and modest supersaturation at annealing stage) is suggested in the formation of high-quality perovskite films.

  3. The Role of Surface Tension in the Crystallization of Metal Halide Perovskites

    KAUST Repository

    Zhumekenov, Ayan A.

    2017-07-06

    The exciting intrinsic properties discovered in single crystals of metal halide perovskites still await their translation into optoelectronic devices. The poor understanding and control of the crystallization process of these materials are current bottlenecks retarding the shift towards single crystal-based optoelectronics. Here we theoretically and experimentally elucidate the role of surface tension in the rapid synthesis of perovskite single crystals by inverse temperature crystallization (ITC). Understanding the nucleation and growth mechanisms enabled us to exploit surface tension to direct the growth of monocrystalline films of perovskites (AMX3, where A = CH3NH3+ or MA; M = Pb2+, Sn2+; X = Br-, I-) on the solution surface. We achieve up to 1 cm2-sized monocrystalline films with thickness on the order of the charge carrier diffusion length (~5-10 µm). Our work paves the way to control the crystallization process of perovskites, including thin film deposition, which is essential to advance the performance benchmarks of perovskite optoelectronics.

  4. High Photoluminescence Quantum Yield in Band Gap Tunable Bromide Containing Mixed Halide Perovskites

    OpenAIRE

    Carolin M. Sutter-Fella Yanbo Li Matin Amani Joel W. Ager III Francesca M. Toma; Eli Yablonovitch Ian D. Sharp and Ali Javey

    2016-01-01

    Hybrid organic–inorganic halide perovskite based semiconductor materials are attractive for use in a wide range of optoelectronic devices because they combine the advantages of suitable optoelectronic attributes and simultaneously low cost solution processability. Here we present a two step low pressure vapor assisted solution process to grow high quality homogeneous CH3NH3PbI3–xBrx perovskite films over the full band gap range of 1.6–2.3 eV. Photoluminescence light in versus light out charac...

  5. All-Inorganic Colloidal Quantum Dot Photovoltaics Employing Solution-Phase Halide Passivation

    KAUST Repository

    Ning, Zhijun

    2012-09-12

    A new solution-phase halide passivation strategy to improve the electronic properties of colloidal quantum dot films is reported. We prove experimentally that the approach leads to an order-of-magnitude increase in mobility and a notable reduction in trap state density. We build solar cells having the highest efficiency (6.6%) reported using all-inorganic colloidal quantum dots. The improved photocurrent results from increased efficiency of collection of infrared-generated photocarriers. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. All-Inorganic Colloidal Quantum Dot Photovoltaics Employing Solution-Phase Halide Passivation

    KAUST Repository

    Ning, Zhijun; Ren, Yuan; Hoogland, Sjoerd; Voznyy, Oleksandr; Levina, Larissa; Stadler, Philipp; Lan, Xinzheng; Zhitomirsky, David; Sargent, Edward H.

    2012-01-01

    A new solution-phase halide passivation strategy to improve the electronic properties of colloidal quantum dot films is reported. We prove experimentally that the approach leads to an order-of-magnitude increase in mobility and a notable reduction in trap state density. We build solar cells having the highest efficiency (6.6%) reported using all-inorganic colloidal quantum dots. The improved photocurrent results from increased efficiency of collection of infrared-generated photocarriers. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Does Taking Photographs Help?

    Science.gov (United States)

    Hand, Sarah

    2010-01-01

    Since many people tend to use photographs as memory anchors, this author decided she wanted to know whether the process of capturing and manipulating an image taken during a learning activity would act as a memory anchor for children's visual, auditory and kinaesthetic memories linked to their cognitive learning at the time. In plain English,…

  8. The coacervation of aqueous solutions of tetraalkylammonium halides

    International Nuclear Information System (INIS)

    Mugnier de Trobriand, Anne.

    1979-09-01

    The coacervation of aqueous solutions of tatraalkylammonium halides in the presence of not of inorganic halides and acids has been studied, considering thermodynamic and spectroscopic aspects. The importance of dispersion forces as well as forces resulting from hydrophobic hydration has been assessed. The analogy between these systems and anionic ion exchange resins has been shown especially for Uranium VI extraction [fr

  9. Definition of a high intensity metal halide discharge reference lamp

    NARCIS (Netherlands)

    Stoffels, W.W.; Baede, A.H.F.M.; Mullen, van der J.J.A.M.; Haverlag, M.; Zissis, G.

    2006-01-01

    The design of a ref. metal halide discharge lamp is presented. This lamp is meant as a common study object for researchers working on metal halide discharge lamps, who by using the same design will be able to compare results between research groups, diagnostic techniques and numerical models. The

  10. Recovery of silver from used X-ray film using alkaline protease from ...

    African Journals Online (AJOL)

    Silver is an important industrial metal used in several areas such as photographic and x-ray films, jewelries, silver wares and electronic objects. Silver is used for photographic film/x-ray film because of its matchless quality as a light-sensitive material for making a photographic image. Silver is not destroyed in the ...

  11. Radiation damage in the alkali halide crystals

    International Nuclear Information System (INIS)

    Diller, K.M.

    1975-10-01

    A general review is given of the experimental data on radiation damage in the alkali halide crystals. A report is presented of an experimental investigation of irradiation produced interstitial dislocation loops in NaCl. These loops are found to exhibit the usual growth and coarsening behaviour during thermal annealing which operates by a glide and self-climb mechanism. It is shown that the recombination of defects in these crystals is a two stage process, and that the loss of interstitials stabilized at the loops is caused by extrinsic vacancies. The theoretical techniques used in simulating point defects in ionic crystals are described. Shell model potentials are derived for all the alkali halide crystals by fitting to bulk crystal data. The fitting is supplemented by calculations of the repulsive second neighbour interactions using methods based on the simple electron gas model. The properties of intrinsic and substitutional impurity defects are calculated. The HADES computer program is used in all the defect calculations. Finally the report returns to the problems of irradiation produced interstitial defects. The properties of H centres are discussed; their structure, formation energies, trapping at impurities and dimerization. The structure, formation energies and mobility of the intermediate and final molecular defects are then discussed. The thermodynamics of interstitial loop formation is considered for all the alklai halide crystals. The nucleation of interstitial loops in NaCl and NaBr is discussed, and the recombination of interstitial and vacancy defects. The models are found to account for all the main features of the experimental data. (author)

  12. Geotagging Photographs in Student Fieldwork

    Science.gov (United States)

    Welsh, Katharine E.; France, Derek; Whalley, W. Brian; Park, Julian R.

    2012-01-01

    This resource paper provides guidance for staff and students on the potential educational benefits, limitations and applications of geotagging photographs. It also offers practical advice for geotagging photographs in a range of fieldwork settings and reviews three free smartphone applications (apps) for geotagging photographs (Flickr, Evernote…

  13. Research Update: Luminescence in lead halide perovskites

    Directory of Open Access Journals (Sweden)

    Ajay Ram Srimath Kandada

    2016-09-01

    Full Text Available Efficiency and dynamics of radiative recombination of carriers are crucial figures of merit for optoelectronic materials. Following the recent success of lead halide perovskites in efficient photovoltaic and light emitting technologies, here we review some of the noted literature on the luminescence of this emerging class of materials. After outlining the theoretical formalism that is currently used to explain the carrier recombination dynamics, we review a few significant works which use photoluminescence as a tool to understand and optimize the operation of perovskite based optoelectronic devices.

  14. Exciton-relaxation dynamics in lead halides

    International Nuclear Information System (INIS)

    Iwanaga, Masanobu; Hayashi, Tetsusuke

    2003-01-01

    We survey recent comprehensive studies of exciton relaxation in the crystals of lead halides. The luminescence and electron-spin-resonance studies have revealed that excitons in lead bromide spontaneously dissociate and both electrons and holes get self-trapped individually. Similar relaxation has been also clarified in lead chloride. The electron-hole separation is ascribed to repulsive correlation via acoustic phonons. Besides, on the basis of the temperature profiles of self-trapped states, we discuss the origin of luminescence components which are mainly induced under one-photon excitation into the exciton band in lead fluoride, lead chloride, and lead bromide

  15. Large polarons in lead halide perovskites

    OpenAIRE

    Miyata, Kiyoshi; Meggiolaro, Daniele; Trinh, M. Tuan; Joshi, Prakriti P.; Mosconi, Edoardo; Jones, Skyler C.; De Angelis, Filippo; Zhu, X.-Y.

    2017-01-01

    Lead halide perovskites show marked defect tolerance responsible for their excellent optoelectronic properties. These properties might be explained by the formation of large polarons, but how they are formed and whether organic cations are essential remain open questions. We provide a direct time domain view of large polaron formation in single-crystal lead bromide perovskites CH3NH3PbBr3 and CsPbBr3. We found that large polaron forms predominantly from the deformation of the PbBr3 ? framewor...

  16. The alkali halide disk technique in infra-red spectrometry : Anomalous behaviour of some samples dispersed in alkali halide disks

    NARCIS (Netherlands)

    Tolk, A.

    1961-01-01

    Some difficulties encountered in the application of the alkali halide disk technique in infra-red spectrometry are discussed. Complications due to interaction of the sample with the alkali halide have been studied experimentally. It was found that the anomalous behaviour of benzoic acid, succinic

  17. High-Performance Single-Crystalline Perovskite Thin-Film Photodetector

    KAUST Repository

    Yang, Zhenqian; Deng, Yuhao; Zhang, Xiaowei; Wang, Suo; Chen, Huazhou; Yang, Sui; Khurgin, Jacob; Fang, Nicholas X.; Zhang, Xiang; Ma, Renmin

    2018-01-01

    The best performing modern optoelectronic devices rely on single-crystalline thin-film (SC-TF) semiconductors grown epitaxially. The emerging halide perovskites, which can be synthesized via low-cost solution-based methods, have achieved substantial

  18. Photograph of the Month

    Science.gov (United States)

    2015-04-01

    For dykes, magma flow direction can be deciphered from various fabrics in the chilled margin (Correa-Gomez et al., 2001, JSG 23, 1415). This photograph represents part of a chilled margin of a appr. N- S trending dyke at Kharghar Hills, Mumbai, Maharashtra, India. The section is sub-vertical. The elongated grooves indicate flow of magma through a fault and the tapered grooves (arrows) connote the flow direction: towards the pointed end of the groove. The magma flowed towards the north in this case. Such fabrics of wall-magma interaction in the Deccan volcanic province prove that dykes injected along fault planes. 19° 2‧ 22.3″ N, 73° 3‧ 28.7″ E. Photograph Ayan Achyuta Misra, Mumbai, India.

  19. Improvements in televisual and photographic inspections of AGRs

    International Nuclear Information System (INIS)

    Hayter, R.; Wadsworth, A.

    1988-01-01

    The visual inspection techniques and equipment used at AGR Power Stations have been improved and updated in the light of need and technological advance, new equipment being developed and introduced where necessary. Specifically this report covers the development and use of: a short TRIUMPH compatible photographic camera 600 mm long x 75 mm dia taking 50 shots on a 35 mm film; a 240 mm dia photographic pod taking high quality 70 mm format photographs of large in-reactor volumes; a photographic camera of cross section 37 x 17 mm for the inspection of helically wound AGR boilers and the subsequent development of this latter device into a state of the art TV inspection camera. (author)

  20. Finding New Perovskite Halides via Machine learning

    Directory of Open Access Journals (Sweden)

    Ghanshyam ePilania

    2016-04-01

    Full Text Available Advanced materials with improved properties have the potential to fuel future technological advancements. However, identification and discovery of these optimal materials for a specific application is a non-trivial task, because of the vastness of the chemical search space with enormous compositional and configurational degrees of freedom. Materials informatics provides an efficient approach towards rational design of new materials, via learning from known data to make decisions on new and previously unexplored compounds in an accelerated manner. Here, we demonstrate the power and utility of such statistical learning (or machine learning via building a support vector machine (SVM based classifier that uses elemental features (or descriptors to predict the formability of a given ABX3 halide composition (where A and B represent monovalent and divalent cations, respectively, and X is F, Cl, Br or I anion in the perovskite crystal structure. The classification model is built by learning from a dataset of 181 experimentally known ABX3 compounds. After exploring a wide range of features, we identify ionic radii, tolerance factor and octahedral factor to be the most important factors for the classification, suggesting that steric and geometric packing effects govern the stability of these halides. The trained and validated models then predict, with a high degree of confidence, several novel ABX3 compositions with perovskite crystal structure.

  1. Finding New Perovskite Halides via Machine learning

    Science.gov (United States)

    Pilania, Ghanshyam; Balachandran, Prasanna V.; Kim, Chiho; Lookman, Turab

    2016-04-01

    Advanced materials with improved properties have the potential to fuel future technological advancements. However, identification and discovery of these optimal materials for a specific application is a non-trivial task, because of the vastness of the chemical search space with enormous compositional and configurational degrees of freedom. Materials informatics provides an efficient approach towards rational design of new materials, via learning from known data to make decisions on new and previously unexplored compounds in an accelerated manner. Here, we demonstrate the power and utility of such statistical learning (or machine learning) via building a support vector machine (SVM) based classifier that uses elemental features (or descriptors) to predict the formability of a given ABX3 halide composition (where A and B represent monovalent and divalent cations, respectively, and X is F, Cl, Br or I anion) in the perovskite crystal structure. The classification model is built by learning from a dataset of 181 experimentally known ABX3 compounds. After exploring a wide range of features, we identify ionic radii, tolerance factor and octahedral factor to be the most important factors for the classification, suggesting that steric and geometric packing effects govern the stability of these halides. The trained and validated models then predict, with a high degree of confidence, several novel ABX3 compositions with perovskite crystal structure.

  2. Local polar fluctuations in lead halide perovskites

    Science.gov (United States)

    Tan, Liang; Yaffe, Omer; Guo, Yinsheng; Brus, Louis; Rappe, Andrew; Egger, David; Kronik, Leeor

    The lead halide perovskites have recently attracted much attention because of their large and growing photovoltaic power conversion efficiencies. However, questions remain regarding the temporal and spatial correlations of the structural fluctuations, their atomistic nature, and how they affect electronic and photovoltaic properties. To address these questions, we have performed a combined ab initio molecular dynamics (MD) and density functional theory (DFT) study on CsPbBr3. We have observed prevalent anharmonic motion in our MD trajectories, with local polar fluctuations involving head-to-head motion of A-site Cs cations coupled with Br window opening. We calculate Raman spectra from the polarizability auto-correlation functions obtained from these trajectories and show that anharmonic A-site cation motion manifests as a broad central peak in the Raman spectrum, which increases in intensity with temperature. A comparison of the experimental Raman spectrum of hybrid organometallic MAPbBr3 and fully inorganic CsPbBr3 suggests that structural fluctuations in lead-halide perovskites is more general than rotation of polar organic cations and is intimately coupled to the inorganic framework.

  3. Large polarons in lead halide perovskites

    Science.gov (United States)

    Miyata, Kiyoshi; Meggiolaro, Daniele; Trinh, M. Tuan; Joshi, Prakriti P.; Mosconi, Edoardo; Jones, Skyler C.; De Angelis, Filippo; Zhu, X.-Y.

    2017-01-01

    Lead halide perovskites show marked defect tolerance responsible for their excellent optoelectronic properties. These properties might be explained by the formation of large polarons, but how they are formed and whether organic cations are essential remain open questions. We provide a direct time domain view of large polaron formation in single-crystal lead bromide perovskites CH3NH3PbBr3 and CsPbBr3. We found that large polaron forms predominantly from the deformation of the PbBr3− frameworks, irrespective of the cation type. The difference lies in the polaron formation time, which, in CH3NH3PbBr3 (0.3 ps), is less than half of that in CsPbBr3 (0.7 ps). First-principles calculations confirm large polaron formation, identify the Pb-Br-Pb deformation modes as responsible, and explain quantitatively the rate difference between CH3NH3PbBr3 and CsPbBr3. The findings reveal the general advantage of the soft [PbX3]− sublattice in charge carrier protection and suggest that there is likely no mechanistic limitations in using all-inorganic or mixed-cation lead halide perovskites to overcome instability problems and to tune the balance between charge carrier protection and mobility. PMID:28819647

  4. American Film Genres: Approaches to a Critical Theory of Popular Film.

    Science.gov (United States)

    Kaminsky, Stuart M.

    This book is divided into twelve sections and contains photographs from many of the films discussed. The introduction defines film genre and describes the general theories behind this book; "The Individual Film" analyzes the film "Little Caesar" as it relates to the genre of gangster films; "Comparative Forms"…

  5. HST Solar Arrays photographed by Electronic Still Camera

    Science.gov (United States)

    1993-01-01

    This close-up view of one of two Solar Arrays (SA) on the Hubble Space Telescope (HST) was photographed with an Electronic Still Camera (ESC), and downlinked to ground controllers soon afterward. Electronic still photography is a technology which provides the means for a handheld camera to electronically capture and digitize an image with resolution approaching film quality.

  6. Astronaut Aldrin is photographed by Astronaut Armstrong on the Moon

    Science.gov (United States)

    1969-01-01

    Apollo 11 Onboard Film -- The deployment of scientific experiments by Astronaut Edwin Aldrin Jr. is photographed by Astronaut Neil Armstrong. Man's first landing on the Moon occurred today at 4:17 p.m. as Lunar Module 'Eagle' touched down gently on the Sea of Tranquility on the east side of the Moon.

  7. Solution growth of single crystal methylammonium lead halide perovskite nanostructures for optoelectronic and photovoltaic applications.

    Science.gov (United States)

    Fu, Yongping; Meng, Fei; Rowley, Matthew B; Thompson, Blaise J; Shearer, Melinda J; Ma, Dewei; Hamers, Robert J; Wright, John C; Jin, Song

    2015-05-06

    Understanding crystal growth and improving material quality is important for improving semiconductors for electronic, optoelectronic, and photovoltaic applications. Amidst the surging interest in solar cells based on hybrid organic-inorganic lead halide perovskites and the exciting progress in device performance, improved understanding and better control of the crystal growth of these perovskites could further boost their optoelectronic and photovoltaic performance. Here, we report new insights on the crystal growth of the perovskite materials, especially crystalline nanostructures. Specifically, single crystal nanowires, nanorods, and nanoplates of methylammonium lead halide perovskites (CH3NH3PbI3 and CH3NH3PbBr3) are successfully grown via a dissolution-recrystallization pathway in a solution synthesis from lead iodide (or lead acetate) films coated on substrates. These single crystal nanostructures display strong room-temperature photoluminescence and long carrier lifetime. We also report that a solid-liquid interfacial conversion reaction can create a highly crystalline, nanostructured MAPbI3 film with micrometer grain size and high surface coverage that enables photovoltaic devices with a power conversion efficiency of 10.6%. These results suggest that single-crystal perovskite nanostructures provide improved photophysical properties that are important for fundamental studies and future applications in nanoscale optoelectronic and photonic devices.

  8. Synthesis, Reactivity and Stability of Aryl Halide Protecting Groups towards Di-Substituted Pyridines

    Directory of Open Access Journals (Sweden)

    Ptoton Mnangat Brian

    2016-03-01

    Full Text Available This paper reports the synthesis and reactivity of different Benzyl derivative protecting groups. The synthesis and stability of Benzyl halides, 4-methoxybenzyl halides, 3,5-dimethoxybenzyl halides, 3,4-dimethoxybenzyl halides, 3,4,5-trimethoxybenzyl halide protecting groups and their reactivity towards nitrogen atom of a di-substituted pyridine ring in formation of pyridinium salts is also reported.

  9. Calibration of photographic and spectroscopic films. 1: Film batch variations of reciprocity failure in IIaO film. 2: Thermal and aging effects in relationship to reciprocity failure. 3: Shifting of reciprocity failure points as a function of thermal and aging effects. Semiannual report, December 1986

    International Nuclear Information System (INIS)

    Peters, K.A.; Atkinson, P.F.; Hammond, E.C. Jr.

    1986-01-01

    Reciprocity failure was examined for IIaO spectroscopic film. Three separate experiments were performed in order to study film batch variations, thermal and aging effects in relationship to reciprocity failure, and shifting of reciprocity failure points as a function of thermal and aging effects. The failure was examined over ranges of time between 5 and 60 seconds. The variation to illuminance was obtained by using thirty neutral density filters. A standard sensitometer device imprinted the wedge pattern on the film as exposure time was subjected to variation. The results indicate that film batch differences, temperature, and aging play an important role in reciprocity failure of IIaO spectroscopic film. A shifting of the failure points was also observed in various batches of film

  10. The creation of defects in ammonium halides by excitons

    International Nuclear Information System (INIS)

    Kim, L.M.

    2002-01-01

    The ammonium halides crystals and alkali halides crystals are analogous by kind chemical bonds and crystalline lattices. The anionic sublattice is identical in this crystals. It is known the main mechanism of defect creation by irradiation is radiationless decay of excitons in alkali halides crystals. The F-, H-centers are formation in this processes. However, F, H-centres are not detected in ammonium halides. The goal of this work is investigation the creation of defects in ammonium halides by excitons. We established that excitons in ammonium chlorides and bromides are similar to excitons in alkali halides. It is known excitons are self-trapped and have identical parameters of the exciton-phonon interaction in both kind crystals. It is supposed, that processes of radiationless disintegration of excitons are identical in ammonium and alkali halides. It is necessary to understand why F-, H-centers are absent in ammonium halides. V k -centres are created by the excitation of the ammonium halides crystals in the absorption band of excitons. It was established by thermoluminescence and spectrums of absorption. The V k -centers begin to migrate at 110-120 K in ammonium chlorides and bromides. The curve of thermoluminescence have peak with maximum at this temperatures. It is known V k -centers in ammonium chlorides have the absorption band at 380 nm. We discovered this absorption band after irradiation of crystals by ultra-violet. In alkali halides F-center is anionic vacancy with electron. The wave function of electron are spread ed at the cations around anionic vacancy. We established the cation NH 4 + in ammonium halides can to capture electron. The ion NH 4 2+ is unsteady. It is disintegrated to NH 3 + and H + . We suppose that excitons in ammonium and alkali halides are disintegrated identically. When cation NH 4 + capture electron, in the anionic sublattice the configuration are created in a direction (100) The indicated configuration is unsteady in relation to a

  11. Treatment of alcaline metals halides for developing crystals

    International Nuclear Information System (INIS)

    Spurney, R.W.

    1974-01-01

    A process is described whereby crystals of an alkaline metal halide may be dried and placed in a crucible for development by the Bridgeman-Stockbarger method. Purified alkaline halides from a suspension are dried and formed into dense cakes of transverse section slightly smaller than that of the crucible, where they are packed, melted and grown into crystals according to the Bridgeman-Stockbarger technique. This method applies to the preparation of alkaline halide crystals, particularly sodium iodide for optical elements or scintillation counters [fr

  12. Alkali metal and alkali earth metal gadolinium halide scintillators

    Science.gov (United States)

    Bourret-Courchesne, Edith; Derenzo, Stephen E.; Parms, Shameka; Porter-Chapman, Yetta D.; Wiggins, Latoria K.

    2016-08-02

    The present invention provides for a composition comprising an inorganic scintillator comprising a gadolinium halide, optionally cerium-doped, having the formula A.sub.nGdX.sub.m:Ce; wherein A is nothing, an alkali metal, such as Li or Na, or an alkali earth metal, such as Ba; X is F, Br, Cl, or I; n is an integer from 1 to 2; m is an integer from 4 to 7; and the molar percent of cerium is 0% to 100%. The gadolinium halides or alkali earth metal gadolinium halides are scintillators and produce a bright luminescence upon irradiation by a suitable radiation.

  13. Degradation of Highly Alloyed Metal Halide Perovskite Precursor Inks: Mechanism and Storage Solutions

    Energy Technology Data Exchange (ETDEWEB)

    Dou, Benjia [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Wheeler, Lance M [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Christians, Jeffrey A [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Moore, David [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Harvey, Steven P [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Berry, Joseph J [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Van Hest, Marinus F [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Barnes, Frank S. [University of Colorado; Shaheen, Sean E. [University of Colorado

    2018-03-02

    Whereas the promise of metal halide perovskite (MHP) photovoltaics (PV) is that they can combine high efficiency with solution-processability, the chemistry occurring in precursor inks is largely unexplored. Herein, we investigate the degradation of MHP solutions based on the most widely used solvents, dimethylformamide (DMF) and dimethyl sulfoxide (DMSO). For the MHP inks studied, which contain formamidinium (FA+), methylammonium (MA+), cesium (Cs+), lead (Pb2+), bromide (Br-), and iodide (I-), dramatic compositional changes are observed following storage of the inks in nitrogen in the dark. We show that hydrolysis of DMF in the precursor solution forms dimethylammonium formate, which subsequently incorporates into the MHP film to compromise the ability of Cs+ and MA+ to stabilize FA+-based MHP. The changes in solution chemistry lead to a modification of the perovskite film stoichiometry, band gap, and structure. The solid precursor salts are stable when ball-milled into a powder, allowing for the storage of large quantities of stoichiometric precursor materials.

  14. Laser post-processing of halide perovskites for enhanced photoluminescence and absorbance

    Science.gov (United States)

    Tiguntseva, E. Y.; Saraeva, I. N.; Kudryashov, S. I.; Ushakova, E. V.; Komissarenko, F. E.; Ishteev, A. R.; Tsypkin, A. N.; Haroldson, R.; Milichko, V. A.; Zuev, D. A.; Makarov, S. V.; Zakhidov, A. A.

    2017-11-01

    Hybrid halide perovskites have emerged as one of the most promising type of materials for thin-film photovoltaic and light-emitting devices. Further boosting their performance is critically important for commercialization. Here we use femtosecond laser for post-processing of organo-metalic perovskite (MAPbI3) films. The high throughput laser approaches include both ablative silicon nanoparticles integration and laser-induced annealing. By using these techniques, we achieve strong enhancement of photoluminescence as well as useful light absorption. As a result, we observed experimentally 10-fold enhancement of absorbance in a perovskite layer with the silicon nanoparticles. Direct laser annealing allows for increasing of photoluminescence over 130%, and increase absorbance over 300% in near-IR range. We believe that the developed approaches pave the way to novel scalable and highly effective designs of perovskite based devices.

  15. Highly Efficient Light-Emitting Diodes of Colloidal Metal-Halide Perovskite Nanocrystals beyond Quantum Size.

    Science.gov (United States)

    Kim, Young-Hoon; Wolf, Christoph; Kim, Young-Tae; Cho, Himchan; Kwon, Woosung; Do, Sungan; Sadhanala, Aditya; Park, Chan Gyung; Rhee, Shi-Woo; Im, Sang Hyuk; Friend, Richard H; Lee, Tae-Woo

    2017-07-25

    Colloidal metal-halide perovskite quantum dots (QDs) with a dimension less than the exciton Bohr diameter D B (quantum size regime) emerged as promising light emitters due to their spectrally narrow light, facile color tuning, and high photoluminescence quantum efficiency (PLQE). However, their size-sensitive emission wavelength and color purity and low electroluminescence efficiency are still challenging aspects. Here, we demonstrate highly efficient light-emitting diodes (LEDs) based on the colloidal perovskite nanocrystals (NCs) in a dimension > D B (regime beyond quantum size) by using a multifunctional buffer hole injection layer (Buf-HIL). The perovskite NCs with a dimension greater than D B show a size-irrespective high color purity and PLQE by managing the recombination of excitons occurring at surface traps and inside the NCs. The Buf-HIL composed of poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonate) (PEDOT:PSS) and perfluorinated ionomer induces uniform perovskite particle films with complete film coverage and prevents exciton quenching at the PEDOT:PSS/perovskite particle film interface. With these strategies, we achieved a very high PLQE (∼60.5%) in compact perovskite particle films without any complex post-treatments and multilayers and a high current efficiency of 15.5 cd/A in the LEDs of colloidal perovskite NCs, even in a simplified structure, which is the highest efficiency to date in green LEDs that use colloidal organic-inorganic metal-halide perovskite nanoparticles including perovskite QDs and NCs. These results can help to guide development of various light-emitting optoelectronic applications based on perovskite NCs.

  16. Radiation chemistry of the alkali halides

    International Nuclear Information System (INIS)

    Robinson, V.J.; Chandratillake, M.R.

    1987-01-01

    By far the most thoroughly investigated group of compounds in solid-state radiation chemistry are the alkali halides. Some of the reasons are undoubtedly practical: large single crystals of high purity are readily prepared. The crystals are transparent over a wide range of wavelengths. They are more sensitive to radiation damage than most other ionic solids. The crystals have simple well-defined structures, and the products of radiolysis have also in many cases been clearly identified by a variety of experimental techniques, the most important being optical methods and electron paramagnetic resonance (EPR). In recent years the application of pulse techniques-radiolysis and laser photolysis-has yielded a wealth of information concerning the mechanisms of the primary processes of radiation damage, on the one hand, and of thermal and photolytic reactions that the radiolysis products undergo, on the other

  17. Photographic Tourism Research: Literature Review

    OpenAIRE

    Virdee, Inderpal

    2017-01-01

    This study reviews the current photographic tourism literature to identify what fields within tourism have been studied by researchers, the contexts, the samples used, the sampling methods employed, the photographic methods and supporting methods used, the data analysis techniques applied and the countries studied. A set of 115 relevant academic articles were selected and assessed using content analysis. The findings showed that overall publications in the field of photographic tourism increa...

  18. The Life of Digital Photographs

    DEFF Research Database (Denmark)

    Larsen, Jonas

    )mobilities of things, practice approaches to photography and multi sited ethnography, this talk discusses and empirically track the life (the conception, birth, transformative years, ageing and death) travel, detours, makeovers and destinations of (analogue and digital) photographs in our present network societies. So...... we can understand the life of more-than representational photographs, and then I turn to my ethnographies to flesh out empirically the life of tourist photographs...

  19. The analysis of track chamber photographs using flying spot digitizers

    CERN Multimedia

    Powell, Brian W

    1966-01-01

    A vast quantity of data pours from the experiments on particle accelerators throughout the world. For example, over 300 000 photographs per week came from the three bubble chambers operating on the CERN PS at the end of 1965. The conventional method of processing these bubble chamber photographs is for each one of them to be examined ('scanned') to see whether it records an interesting particle interaction. The interesting photographs are then passed to hand operated measuring machines to obtain precise measurements of the particle trajectories recorded on the film. Similar measurements are carried out on photographs taken in film spark chamber experiments. This article on the Flying Spot Digitizers at CERN describes one of the most fruitful attempts to speed and make more accurate the process of analysis of bubble and spark chamber photographs. There are two types of Flying Spot Digitizer at CERN — the HPD or Hough Powell Device (named after Professor Hough and the author who, together, initiated the devel...

  20. Catalytic effect of halide additives ball milled with magnesium hydride

    Energy Technology Data Exchange (ETDEWEB)

    Malka, I.E.; Bystrzycki, J. [Department of Advanced Materials and Technologies, Military University of Technology, Kaliskiego 2, 00-908 Warsaw (Poland); Czujko, T. [Department of Advanced Materials and Technologies, Military University of Technology, Kaliskiego 2, 00-908 Warsaw (Poland); CanmetENERGY, Hydrogen Fuel Cells and Transportation Energy, Natural Resources (Canada)

    2010-02-15

    The influence of various halide additives milled with magnesium hydride (MgH{sub 2}) on its decomposition temperature was studied. The optimum amount of halide additive and milling conditions were evaluated. The MgH{sub 2} decomposition temperature and energy of activation reduction were measured by temperature programmed desorption (TPD) and differential scanning calorimetry (DSC). The difference in catalytic efficiency between chlorides and fluorides of the various metals studied is presented. The effects of oxidation state, valence and position in the periodic table for selected halides on MgH{sub 2} decomposition temperature were also studied. The best catalysts, from the halides studied, for magnesium hydride decomposition were ZrF{sub 4}, TaF{sub 5}, NbF{sub 5}, VCl{sub 3} and TiCl{sub 3}. (author)

  1. Single Crystals of Organolead Halide Perovskites: Growth, Characterization, and Applications

    KAUST Repository

    Peng, Wei

    2017-01-01

    Despite their outstanding charge transport characteristics, organolead halide perovskite single crystals grown by hitherto reported crystallization methods are not suitable for most optoelectronic devices due to their small aspect ratios

  2. Dipole-dipole van der Waals interaction in alkali halides

    International Nuclear Information System (INIS)

    Thakur, B.N.; Thakur, K.P.

    1978-01-01

    Values of van der Waals dipole-dipole constants and interaction energetics of alkali halides are reported using the recent data. The values obtained are somewhat larger than those of earlier workers. (orig.) [de

  3. High temperature reactions between molybdenum and metal halides

    International Nuclear Information System (INIS)

    Boeroeczki, A.; Dobos, G.; Josepovits, V.K.; Hars, Gy.

    2006-01-01

    Good colour rendering properties, high intensity and efficacy are of vital importance for high-end lighting applications. These requirements can be achieved by high intensity discharge lamps doped with different metal halide additives (metal halide lamps). To improve their reliability, it is very important to understand the different failure processes of the lamps. In this paper, the corrosion reactions between different metal halides and the molybdenum electrical feed-through electrode are discussed. The reactions were studied in the feed-through of real lamps and on model samples too. X-ray photoelectron spectroscopy (XPS) was used to establish the chemical states. In case of the model samples we have also used atomic absorption spectroscopy (AAS) to measure the reaction product amounts. Based on the measurement results we were able to determine the most corrosive metal halide components and to understand the mechanism of the reactions

  4. Dislocation unpinning model of acoustic emission from alkali halide ...

    Indian Academy of Sciences (India)

    The present paper reports the dislocation unpinning model of acoustic emis- sion (AE) from ... Acoustic emission; dislocation; alkali halide crystals; plastic deformation. ..... [5] T Nishimura, A Tahara and T Kolama, Jpn. Metal Inst. 64, 339 (2000).

  5. Photographic Portraits: Narrative and Memory

    Directory of Open Access Journals (Sweden)

    Brian Roberts

    2011-05-01

    Full Text Available This article is a more general "companion" to the subsequent, Brian ROBERTS (2011 "Interpreting Photographic Portraits: Autobiography, Time Perspectives and Two School Photographs". The article seeks to add to the growing awareness of the importance of visual materials and methods in qualitative social research and to give an introduction to the "photographic self image"—self-portraits and portraits. It focuses on time and memory, including the experiential associations (in consciousness and the senses that the self engenders, thus linking the "visual" (photographic and "auto/biographical". The article attempts to "map" a field—the use of portraiture within social science—drawing on narrative and biographical research, on one side, and photographic portraiture, on the other. In supporting the use of photography in qualitative research it points to the need for researchers to have a greater knowledge of photographic (and art criticism and cognisance of photographic practices. The article does not intend to give a definitive account of photographic portraiture or prescribe in detail how it may be used within social science. It is an initial overview of the development and issues within the area of photographic portraiture and an exploration of relevant methodological issues when images of individuals are employed within social science—so that "portraiture" is better understood and developed within biographical and narrative research. URN: http://nbn-resolving.de/urn:nbn:de:0114-fqs110263

  6. Systemic analysis of thermodynamic properties of lanthanide halides

    International Nuclear Information System (INIS)

    Mirsaidov, U.; Badalov, A.; Marufi, V.K.

    1992-01-01

    System analysis of thermodynamic characteristics of lanthanide halides was carried out. A method making allowances for the influence of spin and orbital moments of momentum of the main states of lanthanide trivalent ions in their natural series was employed. Unknown in literature thermodynamic values were calculated and corrected for certain compounds. The character of lanthanide halide thermodynamic parameter change depending on ordinal number of the metals was ascertained. Pronouncement of tetrad-effect in series of compounds considered was pointed out

  7. Relation between the electroforming voltage in alkali halide-polymer diodes and the bandgap of the alkali halide

    International Nuclear Information System (INIS)

    Bory, Benjamin F.; Wang, Jingxin; Janssen, René A. J.; Meskers, Stefan C. J.; Gomes, Henrique L.; De Leeuw, Dago M.

    2014-01-01

    Electroforming of indium-tin-oxide/alkali halide/poly(spirofluorene)/Ba/Al diodes has been investigated by bias dependent reflectivity measurements. The threshold voltages for electrocoloration and electroforming are independent of layer thickness and correlate with the bandgap of the alkali halide. We argue that the origin is voltage induced defect formation. Frenkel defect pairs are formed by electron–hole recombination in the alkali halide. This self-accelerating process mitigates injection barriers. The dynamic junction formation is compared to that of a light emitting electrochemical cell. A critical defect density for electroforming is 10 25 /m 3 . The electroformed alkali halide layer can be considered as a highly doped semiconductor with metallic transport characteristics

  8. Conversation between photographer Brian Duffy and Grant Scott

    OpenAIRE

    Scott, Grant

    2010-01-01

    Brian Duffy (15 June 1933 – 31 May 2010) was an English photographer and film producer, best remembered for his fashion and portrait photography of the 1960s and 1970s.\\ud \\ud In 1957 Duffy was hired by British Vogue working under art director John Parsons where he remained working until 1963. During this time he worked closely with top models Jean Shrimpton (who he introduced to David Bailey), Paulene Stone, Joy Weston, Jennifer Hocking and Judy Dent.\\ud \\ud With fellow photographers; David ...

  9. Method of producing a pseudo-color photograph with X-rays

    International Nuclear Information System (INIS)

    Tajima, Mataichi.

    1965-01-01

    Conventional black and white X-ray photography cannot simultaneously produce an image on photographic film of a subject having regions of high and low X-ray absorption due to the limitation of photographic density range, gradation and exposure tolerance. This invention records both regions as images of different colors on the same color photographic film. According to a method of this invention for making an X-ray pseudo-color photograph, the subject is directly irradiated by an X-ray beam emergent from an X-ray beam generator, and an X-ray permeation image of the subject is converted into and displayed as a visible light image by means of a fluorescent screen. In one aspect of this invention, there is used a color photographic film which has at least two kinds of sensitive and coloring layers exhibiting the same sensitivity. During the period in which the visible image is displayed, the film is exposed to the visible light in such a way that at least two color filters differing in color and density are successively interposed between the film and the fluorescent screen. In another aspect, a color photographic film is employed having at least two kinds of sensitive and coloring layers exhibiting different sensitivities. During the period in which the visible image is displayed, the film is exposed to visible light by sequentially interposing at least two color filters of different color but of equal density. In this manner, regions comparatively low in X-ray absorption, such as the lungs, and regions comparatively high in absorption, such as the heart, appear as, for example, a blue image and a red image on the color photographic film, respectively. (Takasuka, S.)

  10. Method of producing a pseudo-color photograph with X-rays

    Energy Technology Data Exchange (ETDEWEB)

    Tajima, M

    1965-05-08

    Conventional black and white X-ray photography cannot simultaneously produce an image on photographic film of a subject having regions of high and low X-ray absorption due to the limitation of photographic density range, gradation and exposure tolerance. This invention records both regions as images of different colors on the same color photographic film. According to a method of this invention for making an X-ray pseudo-color photograph, the subject is directly irradiated by an X-ray beam emergent from an X-ray beam generator, and an X-ray permeation image of the subject is converted into and displayed as a visible light image by means of a fluorescent screen. In one aspect of this invention, there is used a color photographic film which has at least two kinds of sensitive and coloring layers exhibiting the same sensitivity. During the period in which the visible image is displayed, the film is exposed to the visible light in such a way that at least two color filters differing in color and density are successively interposed between the film and the fluorescent screen. In another aspect, a color photographic film is employed having at least two kinds of sensitive and coloring layers exhibiting different sensitivities. During the period in which the visible image is displayed, the film is exposed to visible light by sequentially interposing at least two color filters of different color but of equal density. In this manner, regions comparatively low in X-ray absorption, such as the lungs, and regions comparatively high in absorption, such as the heart, appear as, for example, a blue image and a red image on the color photographic film, respectively.

  11. Hybrid lead halide perovskites for light energy conversion: Excited state properties and photovoltaic applications

    Science.gov (United States)

    Manser, Joseph S.

    The burgeoning class of metal halide perovskites constitutes a paradigm shift in the study and application of solution-processed semiconductors. Advancements in thin film processing and our understanding of the underlying structural, photophysical, and electronic properties of these materials over the past five years have led to development of perovskite solar cells with power conversion efficiencies that rival much more mature first and second-generation commercial technologies. It seems only a matter of time before the real-world impact of these compounds is put to the test. Like oxide perovskites, metal halide perovskites have ABX3 stoichiometry, where typically A is a monovalent cation, B a bivalent post-transition metal, and X a halide anion. Characterizing the behavior of photogenerated charges in metal halide perovskites is integral for understanding the operating principles and fundamental limitations of perovskite optoelectronics. The majority of studies outlined in this dissertation involve fundamental study of the prototypical organic-inorganic compound methylammonium lead iodide (CH3NH3PbI 3). Time-resolved pump-probe spectroscopy serves as a principle tool in these investigations. Excitation of a semiconductor can lead to formation of a number different excited state species and electronic complexes. Through analysis of excited state decay kinetics and optical nonlinearities in perovskite thin films, we identify spontaneous formation of a large fraction of free electrons and holes, whose presence is requisite for efficient photovoltaic operation. Following photogeneration of charge carriers in a semiconductor absorber, these species must travel large distances across the thickness of the material to realize large external quantum efficiencies and efficient carrier extraction. Using a powerful technique known as transient absorption microscopy, we directly image long-range carrier diffusion in a CH3NH3PbI 3 thin film. Charges are unambiguously shown to

  12. US/Russian Joint Film Test

    Science.gov (United States)

    Slater, Richard

    1996-01-01

    A joint U.S./Russian film test was conducted during MIR Mission 18 to evaluate the effects of radiation on photographic film during long-duration space flights. Two duplicate sets of film were flown on this MIR mission: one set was processed and evaluated by the NASA/JSC Photographic Laboratory, and the other by the RKK Energia's Photographic Laboratory in Moscow. This preliminary report includes only the results of the JSC evaluation (excluding the SN-10 film which was not available for evaluation at the time this report was written). The final report will include an evaluation by JSC of the SN-10 film and an evaluation of the test data by the RKK Energia. ISC's evaluation of the test data showed the positive film flown was damaged very little when exposed to approximately 8 rads of radiation. Two of the three negative films were significantly damaged and the third film was damaged only moderately.

  13. Autoradiographic enhancement of polaroid film. Final report, 18 April--17 October 1978

    International Nuclear Information System (INIS)

    Manning, R.G.; Pettijohn, R.R.

    1978-11-01

    SRI International has investigated the application of radiotracer photographic image enhancement (PIE) techniques to increase the photographic speed of three Polaroid Films. SRI has a state-of-the art capability in the field of nondestructive photographic image enhancement of original negatives. These procedures have successfully increased optical density, contrast, and resolution of photographic imagery, and thereby increased the information derivable from original negatives

  14. Structure and energetics of trivalent metal halides

    International Nuclear Information System (INIS)

    Hutchinson, F.

    1999-01-01

    Metal trihalide (MX 3 ) systems represent a stern challenge in terms of constructing transferable potential models. Starting from a previously published set of potentials, 'extended' ionic models are developed which, at the outset, include only anion polarization. Deficiencies in these models, particularly for smaller (highly polarizing) cations, axe shown to be significant. For example, crystal structures different to those observed experimentally axe adopted. The potentials axe improved upon by reference to ab initio information available for alkali halides with the 'constraint' that the parameters transfer systematically in a physically transparent manner, for example, in terms of ion radii. The possible influence of anion compression ('breathing') and the relative abundance of anion-anion interactions are considered. Simulation techniques axe developed to allow for the effective simulation of any system symmetry and for the study of transitions between different crystals (constant stress). The developed models are fully tested for a large range of metal trichloride (MCl 3 ) systems. Particular attention is paid to the comparison with recent neutron and X-ray diffraction data on the liquid state. Polarization effects axe shown to be vital in reproducing strong experimental features. The excellent agreement between simulation and experiment allows for differences in experimental procedures to be highlighted. The transferability is further tested by modelling mixtures of the lanthanides with alkali halides with potentials unchanged from the pure systems. The complex evolution of the melt structure is highlighted as the concentration of MCl 3 increases. The effectiveness of the models is tested by reference to dynamical properties. Particular attention is paid to the comparison with Raman scattering data available for a wide range of systems and mixture concentrations. The simulated spectra are generated both by a simple molecular picture of the underlying

  15. Excitonic Effects in Methylammonium Lead Halide Perovskites

    Energy Technology Data Exchange (ETDEWEB)

    Beard, Matthew C [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Chen, Xihan [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Lu, Haipeng [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Yang, Ye [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

    2018-05-01

    The exciton binding energy in methylammonium lead iodide (MAPbI3) is about 10 meV, around 1/3 of the available thermal energy (kBT ~ 26 meV) at room temperature. Thus, exciton populations are not stable at room temperature at moderate photoexcited carrier densities. However, excitonic resonances dominate the absorption onset. Furthermore, these resonances determine the transient absorbance and transient reflectance spectra. The exciton binding energy is a reflection of the Coulomb interaction energy between photoexcited electrons and holes. As such, it serves as a marker for the strength of electron/hole interactions and impacts a variety of phenomena, such as, absorption, radiative recombination, and Auger recombination. In this Perspective, we discuss the role of excitons and excitonic resonances in the optical properties of lead-halide perovskite semiconductors. Finally, we discuss how the strong light-matter interactions induce an optical stark effect splitting the doubly spin degenerate ground exciton states and are easily observed at room temperature.

  16. Structured alkali halides for medical applications

    International Nuclear Information System (INIS)

    Schmitt, B.; Fuchs, M.; Hell, E.; Knuepfer, W.; Hackenschmied, P.; Winnacker, A.

    2002-01-01

    Image plates based on storage phosphors are a major application of radiation defects in insulators. Storage phosphors absorb X-ray quanta creating trapped electron-hole pairs in the material. Optical stimulation of the electron causes recombination leading to light emission. Application of image plates requires an optimal compromise between resolution (represented by the modulation transfer function (MTF)) and sensitivity. In our paper we present a new solution of the problem of combining a high MTF with a high sensitivity by structuring the image plates in form of thin needles acting as light guides. This suppresses the lateral spread of light which is detrimental to resolution. As doped CsBr, e.g. CsBr:Ga [Physica Medica XV (1999) 301], can pose a good storage phosphor evaporated layers are of interest in computed radiography. Needle structured CsI:Tl is used as scintillator in direct radiography [IEEE Trans. Nucl. Sci. 45 (3) (1998)]. CsBr layers have been produced by evaporation in vacuum and in inert gas atmosphere varying pressure and temperature. The resulting structures are of fibrous or columnar nature being in good agreement with the zone model of Thornton [Ann. Rev. Mater. Sci. 7 (1977) 239]. A zone model for CsBr has been developed. Measurements on doped alkali halide image plates having needle structure show good MTF at high sensitivity making a significant progress in image plate technology

  17. High-Performance CH3NH3PbI3-Inverted Planar Perovskite Solar Cells with Fill Factor Over 83% via Excess Organic/Inorganic Halide.

    Science.gov (United States)

    Jahandar, Muhammad; Khan, Nasir; Lee, Hang Ken; Lee, Sang Kyu; Shin, Won Suk; Lee, Jong-Cheol; Song, Chang Eun; Moon, Sang-Jin

    2017-10-18

    The reduction of charge carrier recombination and intrinsic defect density in organic-inorganic halide perovskite absorber materials is a prerequisite to achieving high-performance perovskite solar cells with good efficiency and stability. Here, we fabricated inverted planar perovskite solar cells by incorporation of a small amount of excess organic/inorganic halide (methylammonium iodide (CH 3 NH 3 I; MAI), formamidinium iodide (CH(NH 2 ) 2 I; FAI), and cesium iodide (CsI)) in CH 3 NH 3 PbI 3 perovskite film. Larger crystalline grains and enhanced crystallinity in CH 3 NH 3 PbI 3 perovskite films with excess organic/inorganic halide reduce the charge carrier recombination and defect density, leading to enhanced device efficiency (MAI+: 14.49 ± 0.30%, FAI+: 16.22 ± 0.38% and CsI+: 17.52 ± 0.56%) compared to the efficiency of a control MAPbI 3 device (MAI: 12.63 ± 0.64%) and device stability. Especially, the incorporation of a small amount of excess CsI in MAPbI 3 perovskite film leads to a highly reproducible fill factor of over 83%, increased open-circuit voltage (from 0.946 to 1.042 V), and short-circuit current density (from 18.43 to 20.89 mA/cm 2 ).

  18. "Photographing money" task pricing

    Science.gov (United States)

    Jia, Zhongxiang

    2018-05-01

    "Photographing money" [1]is a self-service model under the mobile Internet. The task pricing is reasonable, related to the success of the commodity inspection. First of all, we analyzed the position of the mission and the membership, and introduced the factor of membership density, considering the influence of the number of members around the mission on the pricing. Multivariate regression of task location and membership density using MATLAB to establish the mathematical model of task pricing. At the same time, we can see from the life experience that membership reputation and the intensity of the task will also affect the pricing, and the data of the task success point is more reliable. Therefore, the successful point of the task is selected, and its reputation, task density, membership density and Multiple regression of task positions, according to which a nhew task pricing program. Finally, an objective evaluation is given of the advantages and disadvantages of the established model and solution method, and the improved method is pointed out.

  19. Parity-Forbidden Transitions and Their Impact on the Optical Absorption Properties of Lead-Free Metal Halide Perovskites and Double Perovskites.

    Science.gov (United States)

    Meng, Weiwei; Wang, Xiaoming; Xiao, Zewen; Wang, Jianbo; Mitzi, David B; Yan, Yanfa

    2017-07-06

    Using density functional theory calculations, we analyze the optical absorption properties of lead (Pb)-free metal halide perovskites (AB 2+ X 3 ) and double perovskites (A 2 B + B 3+ X 6 ) (A = Cs or monovalent organic ion, B 2+ = non-Pb divalent metal, B + = monovalent metal, B 3+ = trivalent metal, X = halogen). We show that if B 2+ is not Sn or Ge, Pb-free metal halide perovskites exhibit poor optical absorptions because of their indirect band gap nature. Among the nine possible types of Pb-free metal halide double perovskites, six have direct band gaps. Of these six types, four show inversion symmetry-induced parity-forbidden or weak transitions between band edges, making them not ideal for thin-film solar cell applications. Only one type of Pb-free double perovskite shows optical absorption and electronic properties suitable for solar cell applications, namely, those with B + = In, Tl and B 3+ = Sb, Bi. Our results provide important insights for designing new metal halide perovskites and double perovskites for optoelectronic applications.

  20. Organometal halide perovskite light-emitting diodes with laminated carbon nanotube electrodes

    Science.gov (United States)

    Shan, Xin; Bade, Sri Ganesh R.; Geske, Thomas; Davis, Melissa; Smith, Rachel; Yu, Zhibin

    2017-08-01

    Organometal halide perovskite light-emitting diodes (LEDs) with laminated carbon nanotube (CNT) electrodes are reported. The LEDs have an indium tin oxide (ITO) bottom electrode, a screen printed methylammonium lead tribromide (MAPbBr3)/polymer composite thin film as the emissive layer, and laminated CNT as the top electrode. The devices can be turned on at 2.2 V, reaching a brightness of 4,960 cd m-2 and a current efficiency of 1.54 cd A-1 at 6.9 V. The greatly simplified fabrication process in this work can potentially lead to the scalable manufacturing of large size and low cost LED panels in the future.

  1. High-Purity Hybrid Organolead Halide Perovskite Nanoparticles Obtained by Pulsed-Laser Irradiation in Liquid

    KAUST Repository

    Amendola, Vincenzo

    2016-11-17

    Nanoparticles of hybrid organic-inorganic perovskites have attracted a great deal of attention due to their variety of optoelectronic properties, their low cost, and their easier integration into devices with complex geometry, compared with microcrystalline, thin-film, or bulk metal halides. Here we present a novel one-step synthesis of organolead bromide perovskite nanocrystals based on pulsed-laser irradiation in a liquid environment (PLIL). Starting from a bulk CHNHPbBr crystal, our PLIL procedure does not involve the use of high-boiling-point polar solvents or templating agents, and runs at room temperature. The resulting nanoparticles are characterized by high crystallinity and are completely free of any microscopic product or organic coating layer. We also demonstrate the straightforward inclusion of laser-generated perovskite nanocrystals in a polymeric matrix to form a nanocomposite with single- and two-photon luminescence properties.

  2. Tailoring Mixed-Halide, Wide-Gap Perovskites via Multistep Conversion Process

    DEFF Research Database (Denmark)

    Bae, Dowon; Palmstrom, Axel; Roelofs, Katherine

    2016-01-01

    Wide-band-gap mixed-halide CH3NH3PbI3–XBrX-based solar cells have been prepared by means of a sequential spin-coating process. The spin-rate for PbI2 as well as its repetitive deposition are important in determining the cross-sectional shape and surface morphology of perovskite, and, consequently......, J–V performance. A perovskite solar cell converted from PbI2 with a dense bottom layer and porous top layer achieved higher device performance than those of analogue cells with a dense PbI2 top layer. This work demonstrates a facile way to control PbI2 film configuration and morphology simply...

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

    Directory of Open Access Journals (Sweden)

    Yajie Jiang

    2015-06-01

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

  4. 78 FR 51463 - Energy Conservation Program: Energy Conservation Standards for Metal Halide Lamp Fixtures

    Science.gov (United States)

    2013-08-20

    ... merging the metal halide lamp fixture and the high-intensity discharge (HID) lamp rulemakings. This NOPR... Conservation Program: Energy Conservation Standards for Metal Halide Lamp Fixtures; Proposed Rule #0;#0;Federal...: Energy Conservation Standards for Metal Halide Lamp Fixtures AGENCY: Office of Energy Efficiency and...

  5. Solvated Positron Chemistry. Competitive Positron Reactions with Halide Ions in Water

    DEFF Research Database (Denmark)

    Christensen, Palle; Pedersen, Niels Jørgen; Andersen, J. R.

    1979-01-01

    It is shown by means of the angular correlation technique that the binding of positrons to halides is strongly influenced by solvation effects. For aqueous solutions we find increasing values for the binding energies between the halide and the positron with increasing mass of the halide...

  6. Quaternary oxide halides of group 15 with zinc and cadmium

    International Nuclear Information System (INIS)

    Rueck, Nadia

    2014-01-01

    The present thesis ''Quaternary oxide halides of group 15 with zinc and cadmium'' deals with the chemical class of oxide halides, which contain d-block element cations and pnicogens. Over the past few years compounds containing pnicogene cations are intensively investigated. The reason for this is the free electron pair of the Pn"3"+ cation, which is responsible for some interesting properties. Free electron pairs do not only impact the spatial structure of molecules but also the properties of materials. The object of this work was the synthesis and characterization of compounds containing Pn"3"+ cations with free electron pairs. Due to the structure-determining effect of these free electron pairs and in combination with halides it is possible to synthesize compounds with low-dimensional structures like chains and layers. In these compounds the structure is separated into halophilic and chalcophilic sub-structures, which are held together only by weak Van der Waals forces.

  7. Two-Dimensional Halide Perovskites for Emerging New- Generation Photodetectors

    DEFF Research Database (Denmark)

    Tang, Yingying; Cao, Xianyi; Chi, Qijin

    2018-01-01

    Compared to their conventional three-dimensional (3D) counterparts, two-dimensional (2D) halide perovskites have attracted more interests recently in a variety of areas related to optoelectronics because of their unique structural characteristics and enhanced performances. In general, there are two...... distinct types of 2D halide perovskites. One represents those perovskites with an intrinsic layered crystal structure (i.e. MX6 layers, M = metal and X = Cl, Br, I), the other defines the perovskites with a 2D nanostructured morphology such as nanoplatelets and nanosheets. Recent studies have shown that 2D...... halide perovskites hold promising potential for the development of new-generation photodetectors, mainly arising from their highly efficient photoluminescence and absorbance, color tunability in the visible-light range and relatively high stability. In this chapter, we present the summary and highlights...

  8. Local Polar Fluctuations in Lead Halide Perovskite Crystals

    Science.gov (United States)

    Yaffe, Omer; Guo, Yinsheng; Tan, Liang Z.; Egger, David A.; Hull, Trevor; Stoumpos, Constantinos C.; Zheng, Fan; Heinz, Tony F.; Kronik, Leeor; Kanatzidis, Mercouri G.; Owen, Jonathan S.; Rappe, Andrew M.; Pimenta, Marcos A.; Brus, Louis E.

    2017-03-01

    Hybrid lead-halide perovskites have emerged as an excellent class of photovoltaic materials. Recent reports suggest that the organic molecular cation is responsible for local polar fluctuations that inhibit carrier recombination. We combine low-frequency Raman scattering with first-principles molecular dynamics (MD) to study the fundamental nature of these local polar fluctuations. Our observations of a strong central peak in the cubic phase of both hybrid (CH3 NH3 PbBr3 ) and all-inorganic (CsPbBr3 ) lead-halide perovskites show that anharmonic, local polar fluctuations are intrinsic to the general lead-halide perovskite structure, and not unique to the dipolar organic cation. MD simulations indicate that head-to-head Cs motion coupled to Br face expansion, occurring on a few hundred femtosecond time scale, drives the local polar fluctuations in CsPbBr3 .

  9. Polar-solvent-free colloidal synthesis of highly luminescent alkylammonium lead halide perovskite nanocrystals

    Science.gov (United States)

    Vybornyi, Oleh; Yakunin, Sergii; Kovalenko, Maksym V.

    2016-03-01

    A novel synthesis of hybrid organic-inorganic lead halide perovskite nanocrystals (CH3NH3PbX3, X = Br or I) that does not involve the use of dimethylformamide or other polar solvents is presented. The reaction between methylamine and PbX2 salts is conducted in a high-boiling nonpolar solvent (1-octadecene) in the presence of oleylamine and oleic acid as coordinating ligands. The resulting nanocrystals are characterized by high photoluminescence quantum efficiencies of 15-50%, outstanding phase purity and tunable shapes (nanocubes, nanowires, and nanoplatelets). Nanoplatelets spontaneously assemble into micrometer-length wires by face-to-face stacking. In addition, we demonstrate amplified spontaneous emission from thin films of green-emitting CH3NH3PbBr3 nanowires with low pumping thresholds of 3 μJ cm-2.A novel synthesis of hybrid organic-inorganic lead halide perovskite nanocrystals (CH3NH3PbX3, X = Br or I) that does not involve the use of dimethylformamide or other polar solvents is presented. The reaction between methylamine and PbX2 salts is conducted in a high-boiling nonpolar solvent (1-octadecene) in the presence of oleylamine and oleic acid as coordinating ligands. The resulting nanocrystals are characterized by high photoluminescence quantum efficiencies of 15-50%, outstanding phase purity and tunable shapes (nanocubes, nanowires, and nanoplatelets). Nanoplatelets spontaneously assemble into micrometer-length wires by face-to-face stacking. In addition, we demonstrate amplified spontaneous emission from thin films of green-emitting CH3NH3PbBr3 nanowires with low pumping thresholds of 3 μJ cm-2. Electronic supplementary information (ESI) available: Materials and methods, additional figures. See DOI: 10.1039/c5nr06890h

  10. Halide-Dependent Electronic Structure of Organolead Perovskite Materials

    KAUST Repository

    Buin, Andrei

    2015-06-23

    © 2015 American Chemical Society. Organometal halide perovskites have recently attracted tremendous attention both at the experimental and theoretical levels. These materials, in particular methylammonium triiodide, are still limited by poor chemical and structural stability under ambient conditions. Today this represents one of the major challenges for polycrystalline perovskite-based photovoltaic technology. In addition to this, the performance of perovskite-based devices is degraded by deep localized states, or traps. To achieve better-performing devices, it is necessary to understand the nature of these states and the mechanisms that lead to their formation. Here we show that the major sources of deep traps in the different halide systems have different origin and character. Halide vacancies are shallow donors in I-based perovskites, whereas they evolve into a major source of traps in Cl-based perovskites. Lead interstitials, which can form lead dimers, are the dominant source of defects in Br-based perovskites, in line with recent experimental data. As a result, the optimal growth conditions are also different for the distinct halide perovskites: growth should be halide-rich for Br and Cl, and halide-poor for I-based perovskites. We discuss stability in relation to the reaction enthalpies of mixtures of bulk precursors with respect to final perovskite product. Methylammonium lead triiodide is characterized by the lowest reaction enthalpy, explaining its low stability. At the opposite end, the highest stability was found for the methylammonium lead trichloride, also consistent with our experimental findings which show no observable structural variations over an extended period of time.

  11. Local coordination of polyvalent metal ions in molten halide mixtures

    International Nuclear Information System (INIS)

    Akdeniz, Z.; Tosi, M.P.

    1989-07-01

    Ample experimental evidence is available in the literature on the geometry and the stability of local coordination for polyvalent metal ions in molten mixtures of their halides with alkali halides. Recent schemes for classifying this evidence are discussed. Dissociation of tetrahedral halocomplexes in good ionic systems can be viewed as a classical Mott problem of bound-state stability in a conducting matrix. More generally, structural coordinates can be constructed from properties of the component elements, to separate out systems with long-lived fourfold or sixfold coordination and to distinguish between these. (author). 11 refs, 1 fig

  12. Thallous and cesium halide materials for use in cryogenic applications

    International Nuclear Information System (INIS)

    Lawless, W.N.

    1983-01-01

    Certain thallous and cesium halides, either used alone or in combination with other ceramic materials, are provided in cryogenic applications such as heat exchange material for the regenerator section of a closed-cycle cryogenic refrigeration section, as stabilizing coatings for superconducting wires, and as dielectric insulating materials. The thallous and cesium halides possess unusually large specific heats at low temperatures, have large thermal conductivities, are nonmagnetic, and are nonconductors of electricity. They can be formed into a variety of shapes such as spheres, bars, rods, or the like and can be coated or extruded onto substrates or wires. (author)

  13. X-ray film calibration

    International Nuclear Information System (INIS)

    Stone, G.F.; Dittmore, C.H.; Henke, B.L.

    1986-01-01

    This paper discusses the use of silver halide x-ray films for imaging and spectroscopy which is limited by the range of intensities that can be recorded and densitometered. Using the manufacturers processing techniques can result in 10 2-3 range in intensity recorded over 0-5 density range. By modifying the chemistry and processing times, ranges of 10 5-6 can be recorded in the same density range. The authors report on x-ray film calibration work and dynamic range improvements. Changes to the processing chemistry and the resulting changes in dynamic range and x-ray sensitivity are discussed

  14. Photovoltaic Rudorffites: Lead-Free Silver Bismuth Halides Alternative to Hybrid Lead Halide Perovskites.

    Science.gov (United States)

    Turkevych, Ivan; Kazaoui, Said; Ito, Eisuke; Urano, Toshiyuki; Yamada, Koji; Tomiyasu, Hiroshi; Yamagishi, Hideo; Kondo, Michio; Aramaki, Shinji

    2017-10-09

    Hybrid CPbX 3 (C: Cs, CH 3 NH 3 ; X: Br, I) perovskites possess excellent photovoltaic properties but are highly toxic, which hinders their practical application. Unfortunately, all Pb-free alternatives based on Sn and Ge are extremely unstable. Although stable and non-toxic C 2 ABX 6 double perovskites based on alternating corner-shared AX 6 and BX 6 octahedra (A=Ag, Cu; B=Bi, Sb) are possible, they have indirect and wide band gaps of over 2 eV. However, is it necessary to keep the corner-shared perovskite structure to retain good photovoltaic properties? Here, we demonstrate another family of photovoltaic halides based on edge-shared AX 6 and BX 6 octahedra with the general formula A a B b X x (x=a+3 b) such as Ag 3 BiI 6 , Ag 2 BiI 5 , AgBiI 4 , AgBi 2 I 7 . As perovskites were named after their prototype oxide CaTiO 3 discovered by Lev Perovski, we propose to name these new ABX halides as rudorffites after Walter Rüdorff, who discovered their prototype oxide NaVO 2 . We studied structural and optoelectronic properties of several highly stable and promising Ag-Bi-I photovoltaic rudorffites that feature direct band gaps in the range of 1.79-1.83 eV and demonstrated a proof-of-concept FTO/c-m-TiO 2 /Ag 3 BiI 6 /PTAA/Au (FTO: fluorine-doped tin oxide, PTAA: poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine], c: compact, m: mesoporous) solar cell with photoconversion efficiency of 4.3 %. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Construction of automatic photographic system for after-glow colour images (AGCI)

    International Nuclear Information System (INIS)

    Kawamura, Kousei; Hashimoto, Tetsuo.

    1995-01-01

    An automatic photographic system of the after-glow colour images (AGCI), which give very useful information related to crystal defects and impurities in white inorganic materials, has been developed. The present system consists of a combination of a photographic part installed in a dark bag with a control personal computer through an interface board. Thus, the photographic procedure of the successive and clear AGCIs could be accomplished from the direct contact of a colour film with an X-rays irradiated rock slices for desired exposure periods and interval times. By using this system, some AGCIs of ammonite fossil showed interesting changes of orange patterns due to structural fossil calcite. (author)

  16. Laboratory EXAFS using photographic method

    International Nuclear Information System (INIS)

    Joshi, S K; Gaur, A; Johari, A; Shrivastava, B D

    2009-01-01

    Laboratory EXAFS facilities have been used since long. However, EXAFS data analysis has not been reported as yet for the spectra recorded photographically. Though from our laboratory we have been reporting various studies employing X-ray spectrographs using the photographic method of registration of EXAFS spectra, but the data has never been analyzed using the Fourier transformation method and fitting with standards. This paper reports the study of copper metal EXAFS spectra at the K-edge recorded photographically employing a 400 mm curved mica crystal Cauchois type spectrograph with 0.5 kW tungsten target X-ray tube. The data obtained in digital form with the help of a microphotometer has been processed using EXAFS data analysis programs Athena and Artemis. The experimental data for copper metal foil have been fitted with the theoretical standards. The results have been compared with those obtained from another laboratory EXAFS set up employing 12 kW Rigaku rotating anode, Johansson-type spectrometer with Si(311) monochromator crystal and scintillation counter. The results have also been compared with those obtained from SSRL. The parameters obtained for the first two shells from the photographic method are comparable with those obtained from the other two methods. The present work shows that the photographic method of registering EXAFS spectra in laboratory set up using fixed target X-ray tubes can also be used for getting structural information at least for the first two coordination shells.

  17. Laboratory EXAFS using photographic method

    Energy Technology Data Exchange (ETDEWEB)

    Joshi, S K [Government College, Badnawar (Dhar)-454660 (India); Gaur, A; Johari, A; Shrivastava, B D, E-mail: joshisantoshk@yahoo.co [School of Studies in Physics, Vikram University, Ujjain-456010 (India)

    2009-11-15

    Laboratory EXAFS facilities have been used since long. However, EXAFS data analysis has not been reported as yet for the spectra recorded photographically. Though from our laboratory we have been reporting various studies employing X-ray spectrographs using the photographic method of registration of EXAFS spectra, but the data has never been analyzed using the Fourier transformation method and fitting with standards. This paper reports the study of copper metal EXAFS spectra at the K-edge recorded photographically employing a 400 mm curved mica crystal Cauchois type spectrograph with 0.5 kW tungsten target X-ray tube. The data obtained in digital form with the help of a microphotometer has been processed using EXAFS data analysis programs Athena and Artemis. The experimental data for copper metal foil have been fitted with the theoretical standards. The results have been compared with those obtained from another laboratory EXAFS set up employing 12 kW Rigaku rotating anode, Johansson-type spectrometer with Si(311) monochromator crystal and scintillation counter. The results have also been compared with those obtained from SSRL. The parameters obtained for the first two shells from the photographic method are comparable with those obtained from the other two methods. The present work shows that the photographic method of registering EXAFS spectra in laboratory set up using fixed target X-ray tubes can also be used for getting structural information at least for the first two coordination shells.

  18. Modulation of Charge Recombination in CsPbBr3 Perovskite Films with Electrochemical Bias

    KAUST Repository

    Scheidt, Rebecca A; Samu, Gergely F.; Janá ky, Csaba; Kamat, Prashant V.

    2017-01-01

    The charging of mesoscopic TiO2 layer in a metal halide perovskite solar cell can influence the overall power conversion efficiency. By employing CsPbBr3 films deposited on a mesoscopic TiO2 film, we have succeeded in probing the influence

  19. THERMODYNAMICS OF MICELLE FORMATION BY 1-METHYL-4-ALKYLPYRIDINIUM HALIDES

    NARCIS (Netherlands)

    BIJMA, K; ENGBERTS, JBFN; HAANDRIKMAN, G; VANOS, NM; BLANDAMER, MJ; BUTT, MD; CULLIS, PM

    This paper reports enthalpies of micellization for a series of 1-methyl-4-alkylpyridinium halide surfactants at 303.2 K with different lengths and degrees of branching of the 4-alkyl chain and different sizes of counterions using two microcalorimeters (LKB 2277 and Omega Microcal). The standard

  20. Empirical formula for the parameters of metallic monovalent halides ...

    African Journals Online (AJOL)

    By collating the data on melting properties and transport coefficients obtained from various experiments and theories for certain halides of monovalent metals, allinclusive linear relationship has been fashioned out. This expression holds between the change in entropy and volume on melting; it is approximately obeyed by ...

  1. Demixing in a metal halide lamp, results from modelling

    NARCIS (Netherlands)

    Beks, M.L.; Hartgers, A.; Mullen, van der J.J.A.M.

    2006-01-01

    Convection and diffusion in the discharge region of a metal halide lamp is studied using a computer model built with the plasma modeling package Plasimo. A model lamp contg. mercury and sodium iodide is studied. The effects of the total lamp pressure on the degree of segregation of the light

  2. Demixing in a metal halide lamp, results from modeling

    NARCIS (Netherlands)

    Beks, M.L.; Hartgers, A.; Mullen, van der J.J.A.M.; Veldhuizen, van E.M.

    2005-01-01

    Metal Halide (MH) lamps are high pressure discharge devices, containing a complex chemical mixture, to emit light on a broad spectrum while maintaining good efficacies. Lamps of this type were first exhibited by General Electric at the 1964 World Fair in New York [1]. They typically consist of an

  3. Monocrystallomimicry in the aerosols of ammonium and cesium halides

    International Nuclear Information System (INIS)

    Melikhov, I.V.; Kitova, E.N.; Kozlovskaya, EhD.; Kamenskaya, A.N.; Mikheev, N.B.; Kulyukhin, S.A.

    1997-01-01

    It is experimentally shown that initial CsI and NH 4 Hal nanocrystals combining into mixed aggregates of polyhedral form (pseudo monocrystals) are formed in the process of cocrystallization of ammonium halide and cesium iodide. The origination and growth of the pseudo monocrystals on the account of successive addition of initial crystals is described by the Fokker-Plank equation [ru

  4. Alternative route to metal halide free ionic liquids

    International Nuclear Information System (INIS)

    Takao, Koichiro; Ikeda, Yasuhisa

    2008-01-01

    An alternative synthetic route to metal halide free ionic liquids using trialkyloxonium salt is proposed. Utility of this synthetic route has been demonstrated by preparing 1-ethyl-3-methylimidazolium tetrafluoroborate ionic liquid through the reaction between 1-methylimidazole and triethyloxonium tetra-fluoroborate in anhydrous ether. (author)

  5. Spectroscopy on metal-halide lamps under varying gravity conditions

    NARCIS (Netherlands)

    Flikweert, A.J.

    2008-01-01

    Worldwide, 20% of all electricity is used for lighting. For this reason, efficient lamps are economically and ecologically important. High intensity discharge (HID) lamps are efficient lamps. The most common HID lamp these days is the metal-halide (MH) lamp. MH lamps have a good colour rendering

  6. Advances and Promises of Layered Halide Hybrid Perovskite Semiconductors

    NARCIS (Netherlands)

    Pedesseau, Laurent; Sapori, Daniel; Traore, Boubacar; Robles, Roberto; Fang, Hong-Hua; Loi, Maria Antonietta; Tsai, Hsinhan; Nie, Wanyi; Blancon, Jean-Christophe; Neukirch, Amanda; Tretiak, Sergei; Mohite, Aditya D.; Katan, Claudine; Even, Jacky; Kepenekian, Mikael

    2016-01-01

    Layered halide hybrid organic inorganic perovskites (HOP) have been the subject of intense investigation before the rise of three-dimensional (3D) HOP and their impressive performance in solar cells. Recently, layered HOP have also been proposed as attractive alternatives for photostable solar cells

  7. Methyl halide emission estimates from domestic biomass burning in Africa

    Science.gov (United States)

    Mead, M. I.; Khan, M. A. H.; White, I. R.; Nickless, G.; Shallcross, D. E.

    Inventories of methyl halide emissions from domestic burning of biomass in Africa, from 1950 to the present day and projected to 2030, have been constructed. By combining emission factors from Andreae and Merlet [2001. Emission of trace gases and aerosols from biomass burning. Global Biogeochemical Cycles 15, 955-966], the biomass burning estimates from Yevich and Logan [2003. An assessment of biofuel use and burning of agricultural waste in the developing world. Global Biogeochemical Cycles 17(4), 1095, doi:10.1029/2002GB001952] and the population data from the UN population division, the emission of methyl halides from domestic biomass usage in Africa has been estimated. Data from this study suggest that methyl halide emissions from domestic biomass burning have increased by a factor of 4-5 from 1950 to 2005 and based on the expected population growth could double over the next 25 years. This estimated change has a non-negligible impact on the atmospheric budgets of methyl halides.

  8. Crystal growth, structure and phase studies on gold halides

    NARCIS (Netherlands)

    Janssen, Eugenius Maria Wilhelmus Janssen

    1977-01-01

    Only very corrosive substances attack gold, the most noble metal. In this study the reactivity and the phase diagrams of gold with the halogens chlorine, bromine and iodine have been investigated. owing to the noble behaviour of gold, its halides are sensitive to heat; on heating they decompose into

  9. On the Boiling Points of the Alkyl Halides.

    Science.gov (United States)

    Correia, John

    1988-01-01

    Discusses the variety of explanations in organic chemistry textbooks of a physical property of organic compounds. Focuses on those concepts explaining attractive forces between molecules. Concludes that induction interactions play a major role in alkyl halides and other polar organic molecules and should be given wider exposure in chemistry texts.…

  10. Students' Understanding of Alkyl Halide Reactions in Undergraduate Organic Chemistry

    Science.gov (United States)

    Cruz-Ramirez de Arellano, Daniel

    2013-01-01

    Organic chemistry is an essential subject for many undergraduate students completing degrees in science, engineering, and pre-professional programs. However, students often struggle with the concepts and skills required to successfully solve organic chemistry exercises. Since alkyl halides are traditionally the first functional group that is…

  11. Dislocation unpinning model of acoustic emission from alkali halide ...

    Indian Academy of Sciences (India)

    AE) from alkali halide crystals. Equations are derived for the strain dependence of the transient AE pulse rate, peak value of the AE pulse rate and the total number of AE pulse emitted. It is found that the AE pulse rate should be maximum for a ...

  12. Analysis and modeling of alkali halide aqueous solutions

    DEFF Research Database (Denmark)

    Kim, Sun Hyung; Anantpinijwatna, Amata; Kang, Jeong Won

    2016-01-01

    on calculations for various electrolyte properties of alkali halide aqueous solutions such as mean ionic activity coefficients, osmotic coefficients, and salt solubilities. The model covers highly nonideal electrolyte systems such as lithium chloride, lithium bromide and lithium iodide, that is, systems...

  13. Strong Carrier-Phonon Coupling in Lead Halide Perovskite Nanocrystals

    NARCIS (Netherlands)

    Iaru, Claudiu M; Geuchies, Jaco J|info:eu-repo/dai/nl/370526090; Koenraad, Paul M; Vanmaekelbergh, Daniël|info:eu-repo/dai/nl/304829137; Silov, Andrei Yu

    2017-01-01

    We highlight the importance of carrier-phonon coupling in inorganic lead halide perovskite nanocrystals. The low-temperature photoluminescence (PL) spectrum of CsPbBr3 has been investigated under a nonresonant and a nonstandard, quasi-resonant excitation scheme, and phonon replicas of the main PL

  14. Adobe Photoshop CC for photographers

    CERN Document Server

    Evening, Martin

    2014-01-01

    Adobe Photoshop for Photographers 2014 Release by Photoshop hall-of-famer and acclaimed digital imaging professional Martin Evening has been fully updated to include detailed instruction for all of the updates to Photoshop CC 2014 on Adobe's Creative Cloud, including significant new features, such as Focus Area selections, enhanced Content-Aware filling, and new Spin and Path blur gallery effects. This guide covers all the tools and techniques photographers and professional image editors need to know when using Photoshop, from workflow guidance to core skills to advanced techniques for profess

  15. A note on photographing otoliths

    African Journals Online (AJOL)

    The sagiu..al otoliths of rlShes have in recent years become importanttuonomic aids. Forthis purpose high quality photographs have become essential to illustrate such fine: structures as the crislae and the colliculi which art often useful in distinguishing between closely related species. The method described bdow proved ...

  16. Globes, Maps, Photographs: Geographic Tools.

    Science.gov (United States)

    McDermott, Paul D.; And Others

    This compilation of reprinted articles that originally appeared in the Journal of Geography from September 1969 through the May 1970 issues, is intended to help teachers use globes, maps, and photographs with skill and understanding. The articles were designed with several objectives in mind: 1) to provide information regarding the design,…

  17. Cultural influences on Facebook photographs.

    Science.gov (United States)

    Huang, Chih-Mao; Park, Denise

    2013-01-01

    Prior research in social psychology indicates that East Asians from collectivistic and interdependent sociocultural systems are more sensitive to contextual information than Westerners, whereas Westerners with individualistic and independent representation have a tendency to process focal and discrete attributes of the environment. Here we have demonstrated that such systematic cultural variations can also be observed in cyberspace, focusing on self-presentation of photographs on Facebook, the most popular worldwide online social network site. We examined cultural differences in face/frame ratios for Facebook profile photographs in two studies. For Study 1, 200 digital profile face photographs of active Facebook users were randomly selected from native and immigrant Taiwanese and Americans. For Study 2, 312 Facebook profiles of undergraduate students of six public universities in East Asia (Hong Kong, Singapore, and Taiwan) and the United States (California and Texas) were randomly selected. Overall, the two studies clearly showed that East Asian Facebook users are more likely to deemphasize their faces compared to Americans. Specifically, East Asians living in Hong Kong, Singapore, and Taiwan exhibited a predilection for context inclusiveness in their profile photographs, whereas Americans tended to prioritize their focal face at the expense of the background. Moreover, East Asian Facebook users had lower intensity of facial expression than Americans on their photographs. These results demonstrate marked cultural differences in context-inclusive styles versus object-focused styles between East Asian and American Facebook users. Our findings extend previous findings from the real world to cyberspace, and provide a novel approach to investigate cognition and behaviors across cultures by using Facebook as a data collection platform.

  18. Cultural influences on Facebook photographs

    Science.gov (United States)

    Huang, Chih-Mao; Park, Denise

    2012-01-01

    Prior research in social psychology indicates that East Asians from collectivistic and interdependent sociocultural systems are more sensitive to contextual information than Westerners, whereas Westerners with individualistic and independent representation have a tendency to process focal and discrete attributes of the environment. Here we have demonstrated that such systematic cultural variations can also be observed in cyberspace, focusing on self-presentation of photographs on Facebook, the most popular worldwide online social network site. We examined cultural differences in face/frame ratios for Facebook profile photographs in two studies. For Study 1, 200 digital profile face photographs of active Facebook users were randomly selected from native and immigrant Taiwanese and Americans. For Study 2, 312 Facebook profiles of undergraduate students of six public universities in East Asia (Hong Kong, Singapore, and Taiwan) and the United States (California and Texas) were randomly selected. Overall, the two studies clearly showed that East Asian Facebook users are more likely to deemphasize their faces compared to Americans. Specifically, East Asians living in Hong Kong, Singapore, and Taiwan exhibited a predilection for context inclusiveness in their profile photographs, whereas Americans tended to prioritize their focal face at the expense of the background. Moreover, East Asian Facebook users had lower intensity of facial expression than Americans on their photographs. These results demonstrate marked cultural differences in context-inclusive styles versus object-focused styles between East Asian and American Facebook users. Our findings extend previous findings from the real world to cyberspace, and provide a novel approach to investigate cognition and behaviors across cultures by using Facebook as a data collection platform. PMID:22468606

  19. Electrochemical behavior of Ti and Ti6Al4V in aqueous solutions of citric acid containing halides

    Directory of Open Access Journals (Sweden)

    Anelise Marlene Schmidt

    2006-12-01

    Full Text Available This paper reports on an investigation of the electrochemical behavior of Ti grade 2 and Ti6Al4V alloy in aqueous citric acid solutions with pH 2.0 containing halide ions. Voltammetric studies of Ti and the alloy in citric acid, with and without chloride ions, indicate that the Ti and Ti alloy presented a passive behavior in the test solutions used. Pitting was observed at 3.0 and 2.5 V/SCE for Ti and Ti6Al4V, respectively, when bromide ions were added to the solution. In solutions containing fluoride ions, dissolution of the film occurred at potentials close to - 1.0 V/SCE in both electrodes. The iodide ions oxidized on the passive oxide film at potentials close to 1.0 V/SCE. EIS results of the materials in citric acid solutions containing chloride ions revealed that the film's resistance increased as the applied potential rose from 0 to 1.0 V. In bromide-containing solutions, breakdown of the film was confirmed at potentials above 2.0 V/SCE in both electrodes. These results suggest film reformation for Ti and the alloy in solutions containing fluoride at potentials within the passive region.

  20. Ionic behavior of organic-inorganic metal halide perovskite based metal-oxide-semiconductor capacitors.

    Science.gov (United States)

    Wang, Yucheng; Zhang, Yuming; Pang, Tiqiang; Xu, Jie; Hu, Ziyang; Zhu, Yuejin; Tang, Xiaoyan; Luan, Suzhen; Jia, Renxu

    2017-05-24

    Organic-inorganic metal halide perovskites are promising semiconductors for optoelectronic applications. Despite the achievements in device performance, the electrical properties of perovskites have stagnated. Ion migration is speculated to be the main contributing factor for the many unusual electrical phenomena in perovskite-based devices. Here, to understand the intrinsic electrical behavior of perovskites, we constructed metal-oxide-semiconductor (MOS) capacitors based on perovskite films and performed capacitance-voltage (C-V) and current-voltage (I-V) measurements of the capacitors. The results provide direct evidence for the mixed ionic-electronic transport behavior within perovskite films. In the dark, there is electrical hysteresis in both the C-V and I-V curves because the mobile negative ions take part in charge transport despite frequency modulation. However, under illumination, the large amount of photoexcited free carriers screens the influence of the mobile ions with a low concentration, which is responsible for the normal C-V properties. Validation of ion migration for the gate-control ability of MOS capacitors is also helpful for the investigation of perovskite MOS transistors and other gate-control photovoltaic devices.

  1. Lead Halide Perovskites as Charge Generation Layers for Electron Mobility Measurement in Organic Semiconductors.

    Science.gov (United States)

    Love, John A; Feuerstein, Markus; Wolff, Christian M; Facchetti, Antonio; Neher, Dieter

    2017-12-06

    Hybrid lead halide perovskites are introduced as charge generation layers (CGLs) for the accurate determination of electron mobilities in thin organic semiconductors. Such hybrid perovskites have become a widely studied photovoltaic material in their own right, for their high efficiencies, ease of processing from solution, strong absorption, and efficient photogeneration of charge. Time-of-flight (ToF) measurements on bilayer samples consisting of the perovskite CGL and an organic semiconductor layer of different thickness are shown to be determined by the carrier motion through the organic material, consistent with the much higher charge carrier mobility in the perovskite. Together with the efficient photon-to-electron conversion in the perovskite, this high mobility imbalance enables electron-only mobility measurement on relatively thin application-relevant organic films, which would not be possible with traditional ToF measurements. This architecture enables electron-selective mobility measurements in single components as well as bulk-heterojunction films as demonstrated in the prototypical polymer/fullerene blends. To further demonstrate the potential of this approach, electron mobilities were measured as a function of electric field and temperature in an only 127 nm thick layer of a prototypical electron-transporting perylene diimide-based polymer, and found to be consistent with an exponential trap distribution of ca. 60 meV. Our study furthermore highlights the importance of high mobility charge transporting layers when designing perovskite solar cells.

  2. D Photographs in Cultural Heritage

    Science.gov (United States)

    Schuhr, W.; Lee, J. D.; Kiel, St.

    2013-07-01

    This paper on providing "oo-information" (= objective object-information) on cultural monuments and sites, based on 3D photographs is also a contribution of CIPA task group 3 to the 2013 CIPA Symposium in Strasbourg. To stimulate the interest in 3D photography for scientists as well as for amateurs, 3D-Masterpieces are presented. Exemplary it is shown, due to their high documentary value ("near reality"), 3D photography support, e.g. the recording, the visualization, the interpretation, the preservation and the restoration of architectural and archaeological objects. This also includes samples for excavation documentation, 3D coordinate calculation, 3D photographs applied for virtual museum purposes and as educational tools. In addition 3D photography is used for virtual museum purposes, as well as an educational tool and for spatial structure enhancement, which in particular holds for inscriptions and in rock arts. This paper is also an invitation to participate in a systematic survey on existing international archives of 3D photographs. In this respect it is also reported on first results, to define an optimum digitization rate for analog stereo views. It is more than overdue, in addition to the access to international archives for 3D photography, the available 3D photography data should appear in a global GIS(cloud)-system, like on, e.g., google earth. This contribution also deals with exposing new 3D photographs to document monuments of importance for Cultural Heritage, including the use of 3D and single lense cameras from a 10m telescope staff, to be used for extremely low earth based airborne 3D photography, as well as for "underwater staff photography". In addition it is reported on the use of captive balloon and drone platforms for 3D photography in Cultural Heritage. It is liked to emphasize, the still underestimated 3D effect on real objects even allows, e.g., the spatial perception of extremely small scratches as well as of nuances in color differences

  3. 31 CFR 91.10 - Photographs.

    Science.gov (United States)

    2010-07-01

    ... 31 Money and Finance: Treasury 1 2010-07-01 2010-07-01 false Photographs. 91.10 Section 91.10 Money and Finance: Treasury Regulations Relating to Money and Finance REGULATIONS GOVERNING CONDUCT IN OR ON THE BUREAU OF THE MINT BUILDINGS AND GROUNDS § 91.10 Photographs. The taking of photographs on...

  4. 22 CFR 51.26 - Photographs.

    Science.gov (United States)

    2010-04-01

    ... 22 Foreign Relations 1 2010-04-01 2010-04-01 false Photographs. 51.26 Section 51.26 Foreign Relations DEPARTMENT OF STATE NATIONALITY AND PASSPORTS PASSPORTS Application § 51.26 Photographs. The applicant must submit with his or her application photographs as prescribed by the Department that are a...

  5. Double Charged Surface Layers in Lead Halide Perovskite Crystals

    KAUST Repository

    Sarmah, Smritakshi P.

    2017-02-01

    Understanding defect chemistry, particularly ion migration, and its significant effect on the surface’s optical and electronic properties is one of the major challenges impeding the development of hybrid perovskite-based devices. Here, using both experimental and theoretical approaches, we demonstrated that the surface layers of the perovskite crystals may acquire a high concentration of positively charged vacancies with the complementary negatively charged halide ions pushed to the surface. This charge separation near the surface generates an electric field that can induce an increase of optical band gap in the surface layers relative to the bulk. We found that the charge separation, electric field, and the amplitude of shift in the bandgap strongly depend on the halides and organic moieties of perovskite crystals. Our findings reveal the peculiarity of surface effects that are currently limiting the applications of perovskite crystals and more importantly explain their origins, thus enabling viable surface passivation strategies to remediate them.

  6. Heterofacial alkylation of alkylenediamines by higher alkyl halides

    International Nuclear Information System (INIS)

    Semenov, V.A.; Kryshko, G.M.; Sokal'skaya, L.I.; Zhukova, N.G.

    1985-01-01

    A study of the physiochemical properties of alkylenediamines substituted by lower alkyls, showed that they possess increased complex-forming ability with respect to salts of different metals as titanium, niobium, zirconium, molybdenum, and zinc. To create a simpler method of synthesis of higher tetraaklyalkylalklyenediamines, based on the use of the accessible domestic raw material, the authors investigated the reaction of alkylenediamines with various alkyl halides. It was established that the best reagents can be obtained using alkyl bromides. It is concluded that the procedure of alkylation of alkylenediamines by higher alkyl halides in the presence of water developed permits the production of terraalkylalkylenediamines in one step with good yield and with purity acceptable for use as extraction reagents

  7. Correlations between entropy and volume of melting in halide salts

    International Nuclear Information System (INIS)

    Akdeniz, Z.; Tosi, M.P.

    1991-09-01

    Melting parameters and transport coefficients in the melt are collated for halides of monovalent, divalent and trivalent metals. A number of systems show a deficit of entropy of melting relative to the linear relationships between entropy change and relative volume change on melting that are found to be approximately obeyed by a majority of halides. These behaviours are discussed on the basis of structural and transport data. The deviating systems are classified into three main classes, namely (i) fast-ion conductors in the high-temperature crystal phase such as AgI, (ii) strongly structured network-like systems such as ZnCl 2 , and (iii) molecular systems melting into associated molecular liquids such as SbCl 3 . (author). 35 refs, 1 fig., 3 tabs

  8. Solution-Phase Synthesis of Cesium Lead Halide Perovskite Nanowires.

    Science.gov (United States)

    Zhang, Dandan; Eaton, Samuel W; Yu, Yi; Dou, Letian; Yang, Peidong

    2015-07-29

    Halide perovskites have attracted much attention over the past 5 years as a promising class of materials for optoelectronic applications. However, compared to hybrid organic-inorganic perovskites, the study of their pure inorganic counterparts, like cesium lead halides (CsPbX3), lags far behind. Here, a catalyst-free, solution-phase synthesis of CsPbX3 nanowires (NWs) is reported. These NWs are single-crystalline, with uniform growth direction, and crystallize in the orthorhombic phase. Both CsPbBr3 and CsPbI3 are photoluminescence active, with composition-dependent temperature and self-trapping behavior. These NWs with a well-defined morphology could serve as an ideal platform for the investigation of fundamental properties and the development of future applications in nanoscale optoelectronic devices based on all-inorganic perovskites.

  9. Local Polar Fluctuations in Lead Halide Perovskite Crystals

    Energy Technology Data Exchange (ETDEWEB)

    Yaffe, Omer; Guo, Yinsheng; Tan, Liang Z.; Egger, David A.; Hull, Trevor; Stoumpos, Constantinos C.; Zheng, Fan; Heinz, Tony F.; Kronik, Leeor; Kanatzidis, Mercouri G.; Owen, Jonathan S.; Rappe, Andrew M.; Pimenta, Marcos A.; Brus, Louis E.

    2017-03-01

    Hybrid lead-halide perovskites have emerged as an excellent class of photovoltaic materials. Recent reports suggest that the organic molecular cation is responsible for local polar fluctuations that inhibit carrier recombination. We combine low-frequency Raman scattering with first-principles molecular dynamics (MD) to study the fundamental nature of these local polar fluctuations. Our observations of a strong central peak in the cubic phase of both hybrid (CH3NH3PbBr3) and all-inorganic (CsPbBr3) leadhalide perovskites show that anharmonic, local polar fluctuations are intrinsic to the general lead-halide perovskite structure, and not unique to the dipolar organic cation. MD simulations indicate that head-tohead Cs motion coupled to Br face expansion, occurring on a few hundred femtosecond time scale, drives the local polar fluctuations in CsPbBr3.

  10. Lamp-Ballast Compatibility Index for Efficient Ceramic Metal Halide Lamp Operation

    OpenAIRE

    Sourish Chatterjee

    2013-01-01

    Development of energy efficient products and exploration of energy saving potential are major challenges for present day’s technology. Ceramic Metal Halide lamp is the latest improved version of metal halide lamp that finds its wide applications in indoor commercial lighting especially in retail shop lighting. This lamp shows better performance in terms of higher lumen per watt and colour constancy in comparison to conventional metal halide lamp. The inherent negative incremental impedance of...

  11. Halides of BET-TTF: novel hydrated molecular metals

    Energy Technology Data Exchange (ETDEWEB)

    Laukhina, E.; Ribera, E.; Vidal-Gancedo, J.; Canadell, E.; Veciana, J.; Rovira, C. [Universidad Autonoma de Barcelona, Bellaterra (Spain). Inst. de Ciencia de Materials; Khasanov, S.; Zorina, L.; Shibaeva, R. [Rossijskaya Akademiya Nauk, Chernogolovka (Russian Federation). Inst. Fiziki Tverdogo Tela; Laukhin, V. [Inst. of Problems of Chemical Physics, RAS, Chernogolovka (Russian Federation); Honold, M.; Nam, M.-S.; Singleton, J. [Clarendon Lab., Univ. of Oxford (United Kingdom)

    2000-01-07

    A hint of superconducting transition has been observed for the first time in a cation radical salt derived from bisethylenethio-tetrathiafulvalene (BET-TTF), the salt (BET-TTF){sub 2}Br.3H{sub 2}O. Here the synthesis, X-ray structure, and physical properties of two hydrated halides of BET-TTF that are isostructural and present stable metallic properties are described. (orig.)

  12. Solvation structures of lithium halides in methanol–water mixtures

    International Nuclear Information System (INIS)

    Sarkar, Atanu; Dixit, Mayank Kumar; Tembe, B.L.

    2015-01-01

    Highlights: • Potentials of mean force for Li + -halides are calculated in methanol–water mixtures. • Stable CIP for x methanol = 1.0 becomes unstable at and below x methanol = 0.75. • The Li + ion is preferentially solvated by methanol molecules. • The halide ions are preferentially solvated by water molecules. - Abstract: The potentials of mean force (PMFs) for the ion pairs, Li + −Cl − , Li + −Br − and Li + −I − have been calculated in five methanol–water compositions. The results obtained are verified by trailing the trajectories and calculating the ion pair distance residence times. Local structures around the ions are studied using the radial distribution functions, density profiles, orientational correlation functions, running coordination numbers and excess coordination numbers. The major change in PMF is observed as the methanol mole fraction (x methanol ) is changed from 1.0 to 0.75. The stable contact ion pair occurring for x methanol = 1.0 becomes unstable at and below x methanol = 0.75. The preferential solvation data show that the halide ions are always preferentially solvated by water molecules. Although the lithium ion is preferentially solvated by methanol molecules, there is significant affinity towards water molecules as well

  13. Methyl halide emissions from greenhouse-grown mangroves

    Science.gov (United States)

    Manley, Steven L.; Wang, Nun-Yii; Walser, Maggie L.; Cicerone, Ralph J.

    2007-01-01

    Two mangrove species, Avicennia germinans and Rhizophora mangle, were greenhouse grown for nearly 1.5 years from saplings. A single individual of each species was monitored for the emission of methyl halides from aerial tissue. During the first 240 days, salinity was incrementally increased with the addition of seawater, and was maintained between 18 and 28‰ for the duration of the study. Exponential growth occurred after 180 days. Methyl halide emissions normalized to leaf area were measured throughout the study and varied dramatically. Emission rates normalized to land area (mg m-2 y-1), assuming a LAI = 5, yielded 82 and 29 for CH3Cl, 10 and 1.6 for CH3Br, and 26 and 11 for CH3I, for A. germinans and R. mangle, respectively. From these preliminary determinations, only CH3I emissions emerge as being of possible global atmospheric significance. This study emphasizes the need for field studies of methyl halide emissions from mangrove forests.

  14. Lasing in robust cesium lead halide perovskite nanowires

    Science.gov (United States)

    Eaton, Samuel W.; Lai, Minliang; Gibson, Natalie A.; Wong, Andrew B.; Dou, Letian; Ma, Jie; Wang, Lin-Wang; Leone, Stephen R.; Yang, Peidong

    2016-01-01

    The rapidly growing field of nanoscale lasers can be advanced through the discovery of new, tunable light sources. The emission wavelength tunability demonstrated in perovskite materials is an attractive property for nanoscale lasers. Whereas organic–inorganic lead halide perovskite materials are known for their instability, cesium lead halides offer a robust alternative without sacrificing emission tunability or ease of synthesis. Here, we report the low-temperature, solution-phase growth of cesium lead halide nanowires exhibiting low-threshold lasing and high stability. The as-grown nanowires are single crystalline with well-formed facets, and act as high-quality laser cavities. The nanowires display excellent stability while stored and handled under ambient conditions over the course of weeks. Upon optical excitation, Fabry–Pérot lasing occurs in CsPbBr3 nanowires with an onset of 5 μJ cm−2 with the nanowire cavity displaying a maximum quality factor of 1,009 ± 5. Lasing under constant, pulsed excitation can be maintained for over 1 h, the equivalent of 109 excitation cycles, and lasing persists upon exposure to ambient atmosphere. Wavelength tunability in the green and blue regions of the spectrum in conjunction with excellent stability makes these nanowire lasers attractive for device fabrication. PMID:26862172

  15. Photographs of the southern heavens

    CERN Document Server

    West, R M

    1975-01-01

    The 1 m Schmidt telescope of the European Southern Observatory (ESO) has been used for a number of sky surveys. In particular a main task has been an examination of the southern night sky between declinations of -20 degrees and -90 degrees . This exercise is known as the ESO(B) Survey (or Quick Blue Survey); some of the more interesting results are shown and are briefly discussed. The photographic plates used were Kodak II a-o. There are photographs of the two Magellanic Clouds and of the galaxy NGC 1313 and the globular cluster NGC 6752. A spectrogram of our Galaxy for wavelengths in the band 3900 A to 4900 A, taken with the telescope's large objective prism is also shown. (0 refs).

  16. Film sheet cassette

    International Nuclear Information System (INIS)

    1981-01-01

    A novel film sheet cassette is described for handling CAT photographic films under daylight conditions and facilitating their imaging. A detailed description of the design and operation of the cassette is given together with appropriate illustrations. The resulting cassette is a low-cost unit which is easily constructed and yet provides a sure light-tight seal for the interior contents of the cassette. The individual resilient fingers on the light-trap permit the ready removal of the slide plate for taking pictures. The stippled, non-electrostatic surface of the pressure plate ensures an air layer and free slidability of the film for removal and withdrawal of the film sheet. The advantage of the daylight system is that a darkroom need not be used for inserting and removing the film in and out of the cassette resulting in a considerable time saving. (U.K.)

  17. Characteristics of sets of diffusion photographic materials for rapid X-ray radiography

    International Nuclear Information System (INIS)

    Gusev, E.A.; Neduv, A.M.; Korolev, A.I.; Mirzoyan, I.N.; Chelnokov, V.B.

    1989-01-01

    Peculiarities of application in X-ray radiography of roentgenographic films, roentgenographic paper, xeroroentgenographic plates and sets of diffusion photographic materials are considered. It is shown that the use of diffusion photographic materials for X-ray radiography permits to reduce the process labour consumption and to considerably reduce the time for the obtaining of a dry positive image and also to reduce the consumption of silver, but the image will preserve high information content. Selts of diffusion photographic materials are developed, which contain bromoiodosilver negative material with silver spraying of 2-3 g/m 3 and transparent positive material on Dacron basis. Prospects of application of sets of diffusion photographic materials in the practice of rapid X-ray radiography to solve the problems of industrial X-ray defectoscopy are panted out

  18. Amine-Free Synthesis of Cesium Lead Halide Perovskite Quantum Dots for Efficient Light-Emitting Diodes

    KAUST Repository

    Yassitepe, Emre; Yang, Zhenyu; Voznyy, Oleksandr; Kim, Younghoon; Walters, Grant; Castañ eda, Juan Andres; Kanjanaboos, Pongsakorn; Yuan, Mingjian; Gong, Xiwen; Fan, Fengjia; Pan, Jun; Hoogland, Sjoerd; Comin, Riccardo; Bakr, Osman; Padilha, Lazaro A.; Nogueira, Ana F.; Sargent, Edward H.

    2016-01-01

    Cesium lead halide perovskite quantum dots (PQDs) have attracted significant interest for optoelectronic applications in view of their high brightness and narrow emission linewidth at visible wavelengths. A remaining challenge is the degradation of PQDs during purification from the synthesis solution. This is attributed to proton transfer between oleic acid and oleylamine surface capping agents that leads to facile ligand loss. Here, a new synthetic method is reported that enhances the colloidal stability of PQDs by capping them solely using oleic acid (OA). Quaternary alkylammonium halides are used as precursors, eliminating the need for oleylamine. This strategy enhances the colloidal stability of OA capped PQDs during purification, allowing us to remove excess organic content in thin films. Inverted red, green, and blue PQD light-emitting diodes (LED) are fabricated for the first time with solution-processed polymer-based hole transport layers due to higher robustness of OA capped PQDs to solution processing. The blue and green LEDs exhibit threefold and tenfold improved external quantum efficiency (EQE), respectively, compared to prior related reports for amine/ammonium capped cross-linked PQDs. The brightest blue LED based on all inorganic CsPb(Br1- xClx)3 PQDs is also reported. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Amine-Free Synthesis of Cesium Lead Halide Perovskite Quantum Dots for Efficient Light-Emitting Diodes

    KAUST Repository

    Yassitepe, Emre

    2016-10-31

    Cesium lead halide perovskite quantum dots (PQDs) have attracted significant interest for optoelectronic applications in view of their high brightness and narrow emission linewidth at visible wavelengths. A remaining challenge is the degradation of PQDs during purification from the synthesis solution. This is attributed to proton transfer between oleic acid and oleylamine surface capping agents that leads to facile ligand loss. Here, a new synthetic method is reported that enhances the colloidal stability of PQDs by capping them solely using oleic acid (OA). Quaternary alkylammonium halides are used as precursors, eliminating the need for oleylamine. This strategy enhances the colloidal stability of OA capped PQDs during purification, allowing us to remove excess organic content in thin films. Inverted red, green, and blue PQD light-emitting diodes (LED) are fabricated for the first time with solution-processed polymer-based hole transport layers due to higher robustness of OA capped PQDs to solution processing. The blue and green LEDs exhibit threefold and tenfold improved external quantum efficiency (EQE), respectively, compared to prior related reports for amine/ammonium capped cross-linked PQDs. The brightest blue LED based on all inorganic CsPb(Br1- xClx)3 PQDs is also reported. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Abiotic Formation of Methyl Halides in the Terrestrial Environment

    Science.gov (United States)

    Keppler, F.

    2011-12-01

    Methyl chloride and methyl bromide are the most abundant chlorine and bromine containing organic compounds in the atmosphere. Since both compounds have relatively long tropospheric lifetimes they can effectively transport halogen atoms from the Earth's surface, where they are released, to the stratosphere and following photolytic oxidation form reactive halogen gases that lead to the chemical destruction of ozone. Methyl chloride and methyl bromide account for more than 20% of the ozone-depleting halogens delivered to the stratosphere and are predicted to grow in importance as the chlorine contribution to the stratosphere from anthropogenic CFCs decline. Today methyl chloride and methyl bromide originate mainly from natural sources with only a minor fraction considered to be of anthropogenic origin. However, until as recently as 2000 most of the methyl chloride and methyl bromide input to the atmosphere was considered to originate from the oceans, but investigations in recent years have clearly demonstrated that terrestrial sources such as biomass burning, wood-rotting fungi, coastal salt marshes, tropical vegetation and organic matter degradation must dominate the atmospheric budgets of these trace gases. However, many uncertainties still exist regarding strengths of both sources and sinks, as well as the mechanisms of formation of these naturally occurring halogenated gases. A better understanding of the atmospheric budget of both methyl chloride and methyl bromide is therefore required for reliable prediction of future ozone depletion. Biotic and abiotic methylation processes of chloride and bromide ion are considered to be the dominant pathways of formation of these methyl halides in nature. In this presentation I will focus on abiotic formation processes in the terrestrial environment and the potential parameters that control their emissions. Recent advances in our understanding of the abiotic formation pathway of methyl halides will be discussed. This will

  1. Effects of Color Complexity in Still Photographs on Mental Effort and Memory.

    Science.gov (United States)

    Gilbert, Kathy; Schleuder, Joan

    For each work assignment, photojournalists must decide whether to use black-and-white or color film and how to frame the picture. These decisions are considered crucial, yet little is known about how the presence of color and design complexity affect how people process the information in photographs. A study tested whether color and design…

  2. Astronaut Ronald Evans photographed during transearth coast EVA

    Science.gov (United States)

    1972-01-01

    Astronaut Ronald E. Evans is photographed performing extravehicular activity (EVA) during the Apollo 17 spacecraft's transearth coast. During his EVA Command Module pilot Evans retrieved film cassettes from the Lunar Sounder, Mapping Camera, and Panoramic Camera. The total time for the transearth EVA was one hour seven minutes 19 seconds, starting at ground elapsed time of 257:25 (2:28 p.m.) amd ending at ground elapsed time of 258:42 (3:35 p.m.) on Sunday, December 17, 1972.

  3. Damage Atlas for Photographic materials

    Directory of Open Access Journals (Sweden)

    Kristel Van Camp

    2010-11-01

    Full Text Available La conservation des documents photographiques peut nécessiter des interventions préventives ou curatives. Ce choix est guidé par leur état de conservation. Une meilleure connaissance des détériorations est donc cruciale. Le répertoire présenté ici essaie de les classifier selon des caractéristiques spécifiques et leur niveau de gravité. Les différents types de dégradation sont illustrés et décrits avec une terminologie précise. L’auteur propose en regard de ceux-ci l’intervention qui semble la plus appropriée. Ce répertoire s’adresse à toutes les personnes concernées par la photographie, qu’ils soient dans le milieu de la conservation ou dans le domaine artistique, dans les musées ou dans les archives. In order to rescue a damaged photographic object, preventive or conservative actions are needed. Knowing the specific characteristics of different types of damage is crucial. A damage atlas can provide these characteristics. With this atlas the damage can be recognised and appropriate actions can be taken. This damage atlas offers a first attempt to such a characterisation in the field of photography. The damage atlas contains images and the necessary information about damage on photographic material. The atlas with special annotations about the terminology and the grade of the damage is meant for everybody who works with photographic material, as well in museums as in archives.

  4. X-ray photographic apparatus

    International Nuclear Information System (INIS)

    1977-01-01

    The X-ray photographic system is designed for medical applications. Two detectors are used for surveys in different planes, and produce electrical signals which are supplied to a comparator. The electron beams are examined according to a system of reference time steps. The apparatus includes a light source and a photo-detector and enables a reference signal to be produced against which the detected signals are compared. The beam source is formed from an electron gun, an extractor electrode and an anode; beam then passes through a collimator. (G.C.)

  5. Specification for personal photographic dosemeters

    International Nuclear Information System (INIS)

    1981-01-01

    The 1981 British/International Standard Specification, prepared under the direction of the Nuclear Engineering Standards Committee and TC85 of the International Organization for Standardization, is described for personal photographic dosemeters. The Standard specifies classification, characteristics and test procedures to determine absorbed doses due to X or gamma radiations (energy less than 3 MeV) and absorbed doses due to beta radiation (max. energy 0.6 to 3 MeV), whether or not accompanied by X, gamma or bremsstrahlung photon radiation. The Standard is particularly applicable to dosemeters intended to be carried on the chest or wrist. (U.K.)

  6. Origin of vertical orientation in two-dimensional metal halide perovskites and its effect on photovoltaic performance.

    Science.gov (United States)

    Chen, Alexander Z; Shiu, Michelle; Ma, Jennifer H; Alpert, Matthew R; Zhang, Depei; Foley, Benjamin J; Smilgies, Detlef-M; Lee, Seung-Hun; Choi, Joshua J

    2018-04-06

    Thin films based on two-dimensional metal halide perovskites have achieved exceptional performance and stability in numerous optoelectronic device applications. Simple solution processing of the 2D perovskite provides opportunities for manufacturing devices at drastically lower cost compared to current commercial technologies. A key to high device performance is to align the 2D perovskite layers, during the solution processing, vertical to the electrodes to achieve efficient charge transport. However, it is yet to be understood how the counter-intuitive vertical orientations of 2D perovskite layers on substrates can be obtained. Here we report a formation mechanism of such vertically orientated 2D perovskite in which the nucleation and growth arise from the liquid-air interface. As a consequence, choice of substrates can be liberal from polymers to metal oxides depending on targeted application. We also demonstrate control over the degree of preferential orientation of the 2D perovskite layers and its drastic impact on device performance.

  7. Critical analysis of stability and performance of organometal halide perovskite solar cells via various fabrication method (Review

    Directory of Open Access Journals (Sweden)

    Suhaimi Suriati

    2017-01-01

    Full Text Available Organometal halide perovskite solar cells (Omh-PSCs have attracted attention due to its unique electrical and optical properties. Ideally, the Omh-PSCs should remain free from degradation under normal operating conditions for several years, preferably tens of years. In order to produce high power conversion efficiency with low potential of degradation, different fabrication methods have been developed. The reported stability of perovskite films can vary significantly and reported to decay substantially up to 20% of its original performance. A thorough understanding of fabrication process upon the stability of the device is regarded as crucial to pave the way for future endeavors. This review summarized and highlighted the recent research of fabrication methods that gave an impact to the stability of perovskite devices.

  8. 10 CFR 431.322 - Definitions concerning metal halide lamp ballasts and fixtures.

    Science.gov (United States)

    2010-01-01

    ... high intensity discharge fixture, the efficiency of a lamp and ballast combination, expressed as a... lamps. Metal halide lamp means a high intensity discharge lamp in which the major portion of the light... 10 Energy 3 2010-01-01 2010-01-01 false Definitions concerning metal halide lamp ballasts and...

  9. Broadly tunable metal halide perovskites for solid-state light-emission applications

    NARCIS (Netherlands)

    Adjokatse, Sampson; Fang, Hong-Hua; Loi, Maria Antonietta

    2017-01-01

    The past two years have witnessed heightened interest in metal-halide perovskites as promising optoelectronic materials for solid-state light emitting applications beyond photovoltaics. Metal-halide perovskites are low-cost solution-processable materials with excellent intrinsic properties such as

  10. Thermal battery. [solid metal halide electrolytes with enhanced electrical conductance after a phase transition

    Science.gov (United States)

    Carlsten, R.W.; Nissen, D.A.

    1973-03-06

    The patent describes an improved thermal battery whose novel design eliminates various disadvantages of previous such devices. Its major features include a halide cathode, a solid metal halide electrolyte which has a substantially greater electrical conductance after a phase transition at some temperature, and a means for heating its electrochemical cells to activation temperature.

  11. Metal-halide lamp design: atomic and molecular data needed

    International Nuclear Information System (INIS)

    Lapatovich, Walter P

    2009-01-01

    Metal-halide lamps are a subset of high intensity discharge (HID) lamps so named because of their high radiance. These lamps are low temperature (∼0.5 eV), weakly ionized plasmas sustained in refractory but light transmissive envelopes by the passage of electric current through atomic and molecular vapors. For commercial applications, the conversion of electric power to light must occur with good efficiency and with sufficient spectral content throughout the visible (380-780 nm) to permit the light so generated to render colors comparable to natural sunlight. This is achieved by adding multiple metals to a basic mercury discharge. Because the vapor pressure of most metals is very much lower than mercury itself, metal-halide salts of the desired metals, having higher vapor pressures, are used to introduce the material into the basic discharge. The metal compounds are usually polyatomic iodides, which vaporize and subsequently dissociate as they diffuse into the bulk plasma. Metals with multiple visible transitions are necessary to achieve high photometric efficiency (efficacy) and good color. Compounds of Sc, Dy, Ho, Tm, Ce, Pr, Yb and Nd are commonly used. The electrons, atoms and radicals are in local thermodynamic equilibrium (LTE), but not with the radiation field. Strong thermal (10 6 K m -1 ) and density gradients are sustained in the discharge. Atomic radiation produced in the high-temperature core transits through colder gas regions where it interacts with cold atoms and un-dissociated molecules before exiting the lamp. Power balance and spectral output of the lamp are directly affected by the strength of atomic transitions. Attempts to simulate the radiative output of functional metal-halide lamps have been successful only in very simple cases. More data (e.g. the atomic transition probabilities of Ce i) are necessary to improve lamp performance, to select appropriate radiators and in scaling the lamp geometry to various wattages for specific applications.

  12. Calcium phosphate cements with strontium halides as radiopacifiers.

    Science.gov (United States)

    López, Alejandro; Montazerolghaem, Maryam; Engqvist, Håkan; Ott, Marjam Karlsson; Persson, Cecilia

    2014-02-01

    High radiopacity is required to monitor the delivery and positioning of injectable implants. Inorganic nonsoluble radiopacifiers are typically used in nondegradable bone cements; however, their usefulness in resorbable cements is limited due to their low solubility. Strontium halides, except strontium fluoride, are ionic water-soluble compounds that possess potential as radiopacifiers. In this study, we compare the radiopacity, mechanical properties, composition, and cytotoxicity of radiopaque brushite cements prepared with strontium fluoride (SrF2 ), strontium chloride (SrCl2 ·6H2 O), strontium bromide (SrBr2 ), or strontium iodide (SrI2 ). Brushite cements containing 10 wt % SrCl2 ·6H2 O, SrBr2 , or SrI2 exhibited equal to or higher radiopacity than commercial radiopaque cements. Furthermore, the brushite crystal lattice in cements that contained the ionic radiopacifiers was larger than in unmodified cements and in cements that contained SrF2 , indicating strontium substitution. Despite the fact that the strontium halides increased the solubility of the cements and affected their mechanical properties, calcium phosphate cements containing SrCl2 ·6H2 O, SrBr2 , and SrI2 showed no significant differences in Saos-2 cell viability and proliferation with respect to the control. Strontium halides: SrCl2 ·6H2 O, SrBr2 , and SrI2 may be potential candidates as radiopacifiers in resorbable biomaterials although their in vivo biocompatibility, when incorporated into injectable implants, is yet to be assessed. Copyright © 2013 Wiley Periodicals, Inc.

  13. Track photographing in 8-m streamer chamber

    International Nuclear Information System (INIS)

    Anisimova, N.Z.; Davidenko, V.A.; Kantserov, V.A.; Rybakov, V.G.; Somov, S.V.

    1981-01-01

    A system for obtaining data from a streamer chamber intended for measuring muon polarization is described. An optical scheme for photographing of tracks in the chamber is given. The photographing process is complicated at the expense of large dimensions and module structure of the chamber as well as due to insufficient for direct photographing brightness of streamers. The system described was tested during a long time in a physical experiment. More than 100 thousand photos have been taken by its means [ru

  14. Metal-Halide Perovskite Transistors for Printed Electronics: Challenges and Opportunities

    KAUST Repository

    Lin, Yen-Hung

    2017-10-12

    Following the unprecedented rise in photovoltaic power conversion efficiencies during the past five years, metal-halide perovskites (MHPs) have emerged as a new and highly promising class of solar-energy materials. Their extraordinary electrical and optical properties combined with the abundance of the raw materials, the simplicity of synthetic routes, and processing versatility make MHPs ideal for cost-efficient, large-volume manufacturing of a plethora of optoelectronic devices that span far beyond photovoltaics. Herein looks beyond current applications in the field of energy, to the area of large-area electronics using MHPs as the semiconductor material. A comprehensive overview of the relevant fundamental material properties of MHPs, including crystal structure, electronic states, and charge transport, is provided first. Thereafter, recent demonstrations of MHP-based thin-film transistors and their application in logic circuits, as well as bi-functional devices such as light-sensing and light-emitting transistors, are discussed. Finally, the challenges and opportunities in the area of MHPs-based electronics, with particular emphasis on manufacturing, stability, and health and environmental concerns, are highlighted.

  15. High Photoluminescence Quantum Yield in Band Gap Tunable Bromide Containing Mixed Halide Perovskites.

    Science.gov (United States)

    Sutter-Fella, Carolin M; Li, Yanbo; Amani, Matin; Ager, Joel W; Toma, Francesca M; Yablonovitch, Eli; Sharp, Ian D; Javey, Ali

    2016-01-13

    Hybrid organic-inorganic halide perovskite based semiconductor materials are attractive for use in a wide range of optoelectronic devices because they combine the advantages of suitable optoelectronic attributes and simultaneously low-cost solution processability. Here, we present a two-step low-pressure vapor-assisted solution process to grow high quality homogeneous CH3NH3PbI3-xBrx perovskite films over the full band gap range of 1.6-2.3 eV. Photoluminescence light-in versus light-out characterization techniques are used to provide new insights into the optoelectronic properties of Br-containing hybrid organic-inorganic perovskites as a function of optical carrier injection by employing pump-powers over a 6 orders of magnitude dynamic range. The internal luminescence quantum yield of wide band gap perovskites reaches impressive values up to 30%. This high quantum yield translates into substantial quasi-Fermi level splitting and high "luminescence or optically implied" open-circuit voltage. Most importantly, both attributes, high internal quantum yield and high optically implied open-circuit voltage, are demonstrated over the entire band gap range (1.6 eV ≤ Eg ≤ 2.3 eV). These results establish the versatility of Br-containing perovskite semiconductors for a variety of applications and especially for the use as high-quality top cell in tandem photovoltaic devices in combination with industry dominant Si bottom cells.

  16. Modulating the Electron-Hole Interaction in a Hybrid Lead Halide Perovskite with an Electric Field.

    Science.gov (United States)

    Leijtens, Tomas; Srimath Kandada, Ajay Ram; Eperon, Giles E; Grancini, Giulia; D'Innocenzo, Valerio; Ball, James M; Stranks, Samuel D; Snaith, Henry J; Petrozza, Annamaria

    2015-12-16

    Despite rapid developments in both photovoltaic and light-emitting device performance, the understanding of the optoelectronic properties of hybrid lead halide perovskites is still incomplete. In particular, the polarizability of the material, the presence of molecular dipoles, and their influence on the dynamics of the photoexcitations remain an open issue to be clarified. Here, we investigate the effect of an applied external electric field on the photoexcited species of CH3NH3PbI3 thin films, both at room temperature and at low temperature, by monitoring the photoluminescence (PL) yield and PL decays. At room temperature we find evidence for electric-field-induced reduction of radiative bimolecular carrier recombination together with motion of charged defects that affects the nonradiative decay rate of the photoexcited species. At low temperature (190 K), we observe a field-induced enhancement of radiative free carrier recombination rates that lasts even after the removal of the field. We assign this to field-induced alignment of the molecular dipoles, which reduces the vibrational freedom of the lattice and the associated local screening and hence results in a stronger electron-hole interaction.

  17. Bio-analytical applications of mid-infrared spectroscopy using silver halide fiber-optic probes

    International Nuclear Information System (INIS)

    Heise, H.M.; Kuepper, L.; Butvina, L.N.

    2002-01-01

    Infrared-spectroscopy has proved to be a powerful method for the study of various biomedical samples, in particular for in-vitro analysis in the clinical laboratory and for non-invasive diagnostics. In general, the analysis of biofluids such as whole blood, urine, microdialysates and bioreactor broth media takes advantage of the fact that a multitude of analytes can be quantified simultaneously and rapidly without the need for reagents. Progress in the quality of infrared silver halide fibers enabled us to construct several flexible fiber-optic probes of different geometries, which are particularly suitable for the measurement of small biosamples. Recent trends show that dry film measurements by mid-infrared spectroscopy could revolutionize analytical tools in the clinical chemistry laboratory, and an example is given. Infrared diagnostic tools show a promising potential for patients, and minimal-invasive blood glucose assays or skin tissue pathology in particular cannot be left out using mid-infrared fiber-based probes. Other applications include the measurement of skin samples including penetration studies of vitamins and constituents of cosmetic cream formulations. A further field is the micro-domain analysis of biopsy samples from bog mummified corpses, and recent results on the chemistry of dermis and hair samples are reported. Another field of application, for which results are reported, is food analysis and bio-reactor monitoring

  18. Epitaxial growth of a methoxy-functionalized quaterphenylene on alkali halide surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Balzer, F., E-mail: fbalzer@mci.sdu.dk [University of Southern Denmark, Mads Clausen Institute, Alsion 2, DK-6400 Sønderborg (Denmark); Sun, R. [University of Southern Denmark, Mads Clausen Institute, Alsion 2, DK-6400 Sønderborg (Denmark); Parisi, J. [University of Oldenburg, Energy and Semiconductor Research Laboratory, Institute of Physics, Carl-von-Ossietzky-Str. 9-11, D-26111 Oldenburg (Germany); Rubahn, H.-G. [University of Southern Denmark, Mads Clausen Institute, Alsion 2, DK-6400 Sønderborg (Denmark); Lützen, A. [University of Bonn, Kekulé Institute of Organic Chemistry and Biochemistry, Gerhard-Domagk-Str. 1, D-53121 Bonn (Germany); Schiek, M. [University of Oldenburg, Energy and Semiconductor Research Laboratory, Institute of Physics, Carl-von-Ossietzky-Str. 9-11, D-26111 Oldenburg (Germany)

    2015-12-31

    The epitaxial growth of the methoxy functionalized para-quaterphenylene (MOP4) on the (001) faces of the alkali halides NaCl and KCl and on glass is investigated by a combination of low energy electron diffraction (LEED), polarized light microscopy (PLM), atomic force microscopy (AFM), and X-ray diffraction (XRD). Both domains from upright molecules as well as fiber-like crystallites from lying molecules form. Neither a wetting layer from lying molecules nor widespread epitaxial fiber growth on the substrates is detected. Our results focus on the upright standing molecules, which condense into a thin film phase with an enlarged layer spacing compared to the bulk phase. - Highlights: • Growth of a methoxy-functionalized para-phenylene on dielectric surfaces is investigated. • Low-energy electron diffraction and X-ray diffraction techniques are employed for structural characterization. • Epitaxial growth of upright molecules only is documented. • Polarized optical microscopy together with atomic force microscopy complements the findings.

  19. Epitaxial growth of a methoxy-functionalized quaterphenylene on alkali halide surfaces

    International Nuclear Information System (INIS)

    Balzer, F.; Sun, R.; Parisi, J.; Rubahn, H.-G.; Lützen, A.; Schiek, M.

    2015-01-01

    The epitaxial growth of the methoxy functionalized para-quaterphenylene (MOP4) on the (001) faces of the alkali halides NaCl and KCl and on glass is investigated by a combination of low energy electron diffraction (LEED), polarized light microscopy (PLM), atomic force microscopy (AFM), and X-ray diffraction (XRD). Both domains from upright molecules as well as fiber-like crystallites from lying molecules form. Neither a wetting layer from lying molecules nor widespread epitaxial fiber growth on the substrates is detected. Our results focus on the upright standing molecules, which condense into a thin film phase with an enlarged layer spacing compared to the bulk phase. - Highlights: • Growth of a methoxy-functionalized para-phenylene on dielectric surfaces is investigated. • Low-energy electron diffraction and X-ray diffraction techniques are employed for structural characterization. • Epitaxial growth of upright molecules only is documented. • Polarized optical microscopy together with atomic force microscopy complements the findings.

  20. Metal-Halide Perovskite Transistors for Printed Electronics: Challenges and Opportunities.

    Science.gov (United States)

    Lin, Yen-Hung; Pattanasattayavong, Pichaya; Anthopoulos, Thomas D

    2017-12-01

    Following the unprecedented rise in photovoltaic power conversion efficiencies during the past five years, metal-halide perovskites (MHPs) have emerged as a new and highly promising class of solar-energy materials. Their extraordinary electrical and optical properties combined with the abundance of the raw materials, the simplicity of synthetic routes, and processing versatility make MHPs ideal for cost-efficient, large-volume manufacturing of a plethora of optoelectronic devices that span far beyond photovoltaics. Herein looks beyond current applications in the field of energy, to the area of large-area electronics using MHPs as the semiconductor material. A comprehensive overview of the relevant fundamental material properties of MHPs, including crystal structure, electronic states, and charge transport, is provided first. Thereafter, recent demonstrations of MHP-based thin-film transistors and their application in logic circuits, as well as bi-functional devices such as light-sensing and light-emitting transistors, are discussed. Finally, the challenges and opportunities in the area of MHPs-based electronics, with particular emphasis on manufacturing, stability, and health and environmental concerns, are highlighted. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Fabrication of Semiconducting Methylammonium Lead Halide Perovskite Particles by Spray Technology

    Science.gov (United States)

    Ahmadian-Yazdi, Mohammad-Reza; Eslamian, Morteza

    2018-01-01

    In this "nano idea" paper, three concepts for the preparation of methylammonium lead halide perovskite particles are proposed, discussed, and tested. The first idea is based on the wet chemistry preparation of the perovskite particles, through the addition of the perovskite precursor solution to an anti-solvent to facilitate the precipitation of the perovskite particles in the solution. The second idea is based on the milling of a blend of the perovskite precursors in the dry form, in order to allow for the conversion of the precursors to the perovskite particles. The third idea is based on the atomization of the perovskite solution by a spray nozzle, introducing the spray droplets into a hot wall reactor, so as to prepare perovskite particles, using the droplet-to-particle spray approach (spray pyrolysis). Preliminary results show that the spray technology is the most successful method for the preparation of impurity-free perovskite particles and perovskite paste to deposit perovskite thin films. As a proof of concept, a perovskite solar cell with the paste prepared by the sprayed perovskite powder was successfully fabricated.

  2. Highly Efficient Visible Colloidal Lead-Halide Perovskite Nanocrystal Light-Emitting Diodes

    Science.gov (United States)

    Yan, Fei; Xing, Jun; Xing, Guichuan; Quan, Lina; Tan, Swee Tiam; Zhao, Jiaxin; Su, Rui; Zhang, Lulu; Chen, Shi; Zhao, Yawen; Huan, Alfred; Sargent, Edward H.; Xiong, Qihua; Demir, Hilmi Volkan

    2018-05-01

    Lead-halide perovskites have been attracting attention for potential use in solid-state lighting. Following the footsteps of solar cells, the field of perovskite light-emitting diodes (PeLEDs) has been growing rapidly. Their application prospects in lighting, however, remain still uncertain due to a variety of shortcomings in device performance including their limited levels of luminous efficiency achievable thus far. Here we show high-efficiency PeLEDs based on colloidal perovskite nanocrystals (PeNCs) synthesized at room temperature possessing dominant first-order excitonic radiation (enabling a photoluminescence quantum yield of 71% in solid film), unlike in the case of bulk perovskites with slow electron-hole bimolecular radiative recombination (a second-order process). In these PeLEDs, by reaching charge balance in the recombination zone, we find that the Auger nonradiative recombination, with its significant role in emission quenching, is effectively suppressed in low driving current density range. In consequence, these devices reach a record high maximum external quantum efficiency of 12.9% reported to date and an unprecedentedly high power efficiency of 30.3 lm W-1 at luminance levels above 1000 cd m-2 as required for various applications. These findings suggest that, with feasible levels of device performance, the PeNCs hold great promise for their use in LED lighting and displays.

  3. Fabrication of Semiconducting Methylammonium Lead Halide Perovskite Particles by Spray Technology.

    Science.gov (United States)

    Ahmadian-Yazdi, Mohammad-Reza; Eslamian, Morteza

    2018-01-10

    In this "nano idea" paper, three concepts for the preparation of methylammonium lead halide perovskite particles are proposed, discussed, and tested. The first idea is based on the wet chemistry preparation of the perovskite particles, through the addition of the perovskite precursor solution to an anti-solvent to facilitate the precipitation of the perovskite particles in the solution. The second idea is based on the milling of a blend of the perovskite precursors in the dry form, in order to allow for the conversion of the precursors to the perovskite particles. The third idea is based on the atomization of the perovskite solution by a spray nozzle, introducing the spray droplets into a hot wall reactor, so as to prepare perovskite particles, using the droplet-to-particle spray approach (spray pyrolysis). Preliminary results show that the spray technology is the most successful method for the preparation of impurity-free perovskite particles and perovskite paste to deposit perovskite thin films. As a proof of concept, a perovskite solar cell with the paste prepared by the sprayed perovskite powder was successfully fabricated.

  4. Hot working alkali halides for laser window applications

    International Nuclear Information System (INIS)

    Koepke, B.G.; Anderson, R.H.; Stokes, R.J.

    1975-01-01

    The techniques used to hot work alkali halide crystals into laser window blanks are reviewed. From the point of view of high power laser window applications one of the materials with a high figure of merit is KCl. Thus the materials examined are KCl and alloys of KCl-KBr containing 5 mole percent KBr. The fabrication techniques include conventional and constrained press forging, isostatic press forging and hot rolling. Optical properties are paramount to the ultimate usefulness of these materials. Results on the optical properties of the hot worked material are included together with mechanical properties and microstructural data

  5. Effect of chromone-substituted benzothiazolium halides on photosynthetic processes

    International Nuclear Information System (INIS)

    Kralova, K.; Sersen, F.; Gasparova, R.; Lacova, M.

    1998-01-01

    The effects of 3-R 2 -2[2-(6-R 1 -chromone-3-yl)ethenyl]benzothiazolium halides (CBH) on photosynthetic electron transport in spinach chloroplasts and in the legal suspension of Chlorella vulgaris were investigated. Using EPR spectroscopy it was confirmed that these compounds containing in their molecules two heterocyclic skeletons, namely benzothiazole and chromone, interact with the intermediate D + , corresponding to the tyrosine radical Tyr D situated in D 2 protein on the donor side of photosystem 2. Consequently, higher concentrations of CBH inhibited oxygen evolution rate in Chlorella vulgaris and the inhibitory effectiveness depended on the lipophilicity of the of the compound. (authors)

  6. Genesis, challenges and opportunities for colloidal lead halide perovskite nanocrystals

    Science.gov (United States)

    Akkerman, Quinten A.; Rainò, Gabriele; Kovalenko, Maksym V.; Manna, Liberato

    2018-05-01

    Lead halide perovskites (LHPs) in the form of nanometre-sized colloidal crystals, or nanocrystals (NCs), have attracted the attention of diverse materials scientists due to their unique optical versatility, high photoluminescence quantum yields and facile synthesis. LHP NCs have a `soft' and predominantly ionic lattice, and their optical and electronic properties are highly tolerant to structural defects and surface states. Therefore, they cannot be approached with the same experimental mindset and theoretical framework as conventional semiconductor NCs. In this Review, we discuss LHP NCs historical and current research pursuits, challenges in applications, and the related present and future mitigation strategies explored.

  7. Status quo of ceramic material for metal halide discharge lamps

    International Nuclear Information System (INIS)

    Kappen, Theo G M M

    2005-01-01

    Polycrystalline alumina is an excellent ceramic material for use as the envelope for metal halide discharge lamps. Although this material was introduced in the mid-1960s, and is thus already known for several decades, recent years have seen considerable effort aimed at further development of these ceramic envelope materials. Developments are not only in the field of ceramic shaping technologies, but are also concentrated on the material properties of the ceramic material itself. Optical, mechanical as well as the chemical properties of the ceramic envelope are strongly controlled by the shape as well as the microstructure of the ceramics used

  8. Evaluation of field test equipment for halide and DOP testing

    International Nuclear Information System (INIS)

    Schreiber, K.L.; Kovach, J.L.

    1975-01-01

    The Nucon Testing Services Department, field testing at power reactor sites, has performed tests using R-11, R-12, and R-112 in conjunction with gas chromatographs and direct reading halide detectors. The field operational experience with these detector systems, thus sensitivity, precision, and manner of field calibration, are presented. Laboratory experiments regarding 3 H-tagged methyl iodide for in place leak testing of adsorber systems indicate a low hazard, high reliability process for leak testing in facilities where atmospheric cross contamination occurs. (U.S.)

  9. Synthesis of halide- and solvent free metal borohydrides

    DEFF Research Database (Denmark)

    Grinderslev, Jakob; Møller, Kasper Trans; Richter, Bo

    have challenges due to their high desorption kinetics and limited reversibility at moderate conditions.[2],[3],[4] In this work, we present a new approach to synthesize halide- and solvent free metal borohydrides starting from the respective metal hydride. The synthetic strategy ensures that no metal...... to the metal. Hence, the powdered M(BH4)3∙DMS is heated to 140 °C for 4 hours to obtain pure M(BH4)3. The rare-earth metal borohydrides have been investigated by infrared spectroscopy and thermal analysis (TGA-DSC-MS). Furthermore, the structural trends are investigated by synchrotron radiation powder X...

  10. Cation-Dependent Light-Induced Halide Demixing in Hybrid Organic-Inorganic Perovskites.

    Science.gov (United States)

    Sutter-Fella, Carolin M; Ngo, Quynh P; Cefarin, Nicola; Gardner, Kira L; Tamura, Nobumichi; Stan, Camelia V; Drisdell, Walter S; Javey, Ali; Toma, Francesca M; Sharp, Ian D

    2018-06-13

    Mixed cation metal halide perovskites with increased power conversion efficiency, negligible hysteresis, and improved long-term stability under illumination, moisture, and thermal stressing have emerged as promising compounds for photovoltaic and optoelectronic applications. Here, we shed light on photoinduced halide demixing using in situ photoluminescence spectroscopy and in situ synchrotron X-ray diffraction (XRD) to directly compare the evolution of composition and phase changes in CH(NH 2 ) 2 CsPb-halide (FACsPb-) and CH 3 NH 3 Pb-halide (MAPb-) perovskites upon illumination, thereby providing insights into why FACs-perovskites are less prone to halide demixing than MA-perovskites. We find that halide demixing occurs in both materials. However, the I-rich domains formed during demixing accumulate strain in FACsPb-perovskites but readily relax in MA-perovskites. The accumulated strain energy is expected to act as a stabilizing force against halide demixing and may explain the higher Br composition threshold for demixing to occur in FACsPb-halides. In addition, we find that while halide demixing leads to a quenching of the high-energy photoluminescence emission from MA-perovskites, the emission is enhanced from FACs-perovskites. This behavior points to a reduction of nonradiative recombination centers in FACs-perovskites arising from the demixing process and buildup of strain. FACsPb-halide perovskites exhibit excellent intrinsic material properties with photoluminescence quantum yields that are comparable to MA-perovskites. Because improved stability is achieved without sacrificing electronic properties, these compositions are better candidates for photovoltaic applications, especially as wide bandgap absorbers in tandem cells.

  11. Scanning negatives and slides digitizing your photographic archive

    CERN Document Server

    Steinhoff, Sascha

    2009-01-01

    Many photographers have either moved into digital photography exclusively or use both analog and digital media in their work. In either case, there is sure to be an archive of slides and negatives that cannot be directly integrated into the new digital workflow, nor can it be archived in a digital format. Increasingly, photographers are trying to bridge this gap with the use of high-performance film scanners. In this 2nd edition, you will learn how to achieve the best possible digital image from a negative or a slide, and how to build a workflow to make this process efficient, repeatable, and reliable. The author uses Nikon's film scanners, but all steps can easily be accomplished while using a different scanner. The most common software tools for scanning (SilverFast, VueScan, NikonScan) are not only covered extensively in the book, but trial versions are also provided on a DVD, which also contains other useful tools for image editing, as well as numerous sample scans.

  12. Photographic quality assurance in diagnostic radiology, nuclear medicine, and radiation therapy. Volume II. Photographic processing, quality assurance, and the evaluation of photographic materials. Final report

    International Nuclear Information System (INIS)

    Gray, J.E.; Vucich, J.J.

    1977-03-01

    Contents: Sensitometers, densitometers, and testing equipment; Pitfalls of the photographic (and radiographic) process; Evaluation and optimization of photographic processes; Quality assurance; Odds 'n' ends

  13. Photographing travel of classical windturbines in Europe; Oshu Koen fusha satsuei ryoko

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, H.

    1997-03-01

    Travel in Europe for taking photographs of classical windturbines is reported. The Netherlands which is a representative windturbine country, Spain which is a theme country of this travel, Greece which is a root country of the windmills, and the UK with the Windturbine Museum were visited. In the Netherlands, photographs of Kinder d`eiche Windturbine, Leiden de Valk Windturbine Museum, and a windturbine in the south end of Amstle Park were taken. Photographs of don Quijote Windturbine at Campo de Criptana in Spain, and Crete Windturbine and sail-type windturbine in the Rhodes Island, Greece were taken. In the UK, the Windturbine Museum was visited at Wimbledon. After coming back to Japan, films were exposed. The walls of windturbines were dark due to insufficient exposure against the light sky. In spite of consideration of the exposure, 70% of the photographs of windturbine walls were still dark. Only 10% of them can be available. This may be a limit of amateur photographer. Professional photographer may be complete. 12 figs.

  14. "Photographers Are the Devil": An Essay in the Historiography of Photographing Schools

    Science.gov (United States)

    Hardcastle, John

    2013-01-01

    Today, the use of photographs in publications and exhibitions is commonplace, but this was not always so. This article shows how photographs of certain schools that have had lasting impact on design stand in ambiguous relationships to the buildings themselves. Photographs function as part of the design process; they record details of construction…

  15. Effect of cuprous halide interlayers on the device performance of ZnPc/C{sub 60} organic solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jinho; Park, Dasom; Heo, Ilsu; Yim, Sanggyu, E-mail: sgyim@kookmin.ac.kr

    2014-10-15

    Highlights: • Effect of CuX interlayers on subsequently deposited films and devices was studied. • CuI is the most effective for the performance of ZnPc/C{sub 60}-based solar cells. • Results were related to the molecular geometry of ZnPc and HOMO level of interlayers. - Abstract: The effect of various cuprous halide (CuX) interlayers introduced between a poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) layer and zinc phthalocyanine (ZnPc) layer on the physical properties of the ZnPc thin films and device performances of ZnPc/C{sub 60}-based small-molecule organic solar cells was studied. Strong substrate–molecule interaction between the CuX and ZnPc partly converted surface-perpendicular stacking geometry of ZnPc molecules into surface-parallel one. This flat-lying geometry led to an enhancement in electronic absorption and charge transport within the ZnPc films. As a result, the overall power conversion efficiency of the cell with CuI interlayer increased by ∼37%. In the case of the cells with CuBr and CuCl interlayer, however, the enhancement in device performances was limited because of the reduced conversion of the molecular geometry and increased energy barrier for hole extraction due to the low highest occupied molecular orbital level of the interlayer.

  16. Effect of cuprous halide interlayers on the device performance of ZnPc/C60 organic solar cells

    International Nuclear Information System (INIS)

    Lee, Jinho; Park, Dasom; Heo, Ilsu; Yim, Sanggyu

    2014-01-01

    Highlights: • Effect of CuX interlayers on subsequently deposited films and devices was studied. • CuI is the most effective for the performance of ZnPc/C 60 -based solar cells. • Results were related to the molecular geometry of ZnPc and HOMO level of interlayers. - Abstract: The effect of various cuprous halide (CuX) interlayers introduced between a poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) layer and zinc phthalocyanine (ZnPc) layer on the physical properties of the ZnPc thin films and device performances of ZnPc/C 60 -based small-molecule organic solar cells was studied. Strong substrate–molecule interaction between the CuX and ZnPc partly converted surface-perpendicular stacking geometry of ZnPc molecules into surface-parallel one. This flat-lying geometry led to an enhancement in electronic absorption and charge transport within the ZnPc films. As a result, the overall power conversion efficiency of the cell with CuI interlayer increased by ∼37%. In the case of the cells with CuBr and CuCl interlayer, however, the enhancement in device performances was limited because of the reduced conversion of the molecular geometry and increased energy barrier for hole extraction due to the low highest occupied molecular orbital level of the interlayer

  17. Digital Restoration from Start to Finish How to repair old and damaged photographs

    CERN Document Server

    Ctein,

    2010-01-01

    Digital Restoration: Start to Finish 2nd edition guides you step-by-step through the entire process of restoring old photographs and repairing new ones using Adobe Photoshop, Picture Window, and now Elements. Nothing is left out, from choosing the right hardware and software and getting the photographs into the computer, to getting the finished photo out of the computer and preserving it for posterity.  LEARN HOW TO: Scan faded and damaged prints or films Improve snapshots with Shadow/Highlight adjustment Correct uneven exposure Fix color and skin tones quickly with Curves, plug-ins, a

  18. Halide Perovskites: New Science or ``only'' future Energy Converters?

    Science.gov (United States)

    Cahen, David

    Over the years many new ideas and systems for photovoltaic, PV, solar to electrical energy conversion have been explored, but only a few have really impacted PV's role as a more sustainable, environmentally less problematic and safer source of electrical power than fossil or nuclear fuel-based generation. Will Halide Perovskites, HaPs, be able to join the very select group of commercial PV options? To try to address this question, we put Halide Perovskite(HaP) cells in perspective with respect to other PV cells. Doing so also allows to identify fundamental scientific issues that can be important for PV and beyond. What remains to be seen is if those issues lead to new science or scientific insights or additional use of existing models. Being more specific is problematic, given the fact that this will be 4 months after writing this abstract. Israel National Nano-initiative, Weizmann Institute of Science's Alternative sustainable Energy Research Initiative; Israel Ministries of -Science and of -Infrastructure, Energy & Water.

  19. Melting and liquid structure of polyvalent metal halides

    International Nuclear Information System (INIS)

    Tosi, M.P.

    1992-08-01

    A short review is given of recent progress in determining and understanding liquid structure types and melting mechanisms for halides of polyvalent metals. The nature of the preferred local coordination for the polyvalent metal ion in the melt can usually be ascertained from data on liquid mixtures with halogen-donating alkali halides. The stability of these local coordination states and the connectivity that arises between them in the approach to the pure melt determines the character of its short-range and possible medium-range order. A broad classification of structural and melting behaviours can be given on the basis of measured melting parameters and transport coefficients for many compounds, in combination with the available diffraction data on the liquid structure of several compounds. Correlations have been shown to exist with a simple indicator of the nature of the chemical bond and also with appropriate parameters of ionic models, wherever the latter are usefully applicable for semiquantitative calculations of liquid structure. Consequences on the mechanisms for valence electron localization in solutions of metallic elements into strongly structured molten salts are also briefly discussed. (author). 46 refs, 4 figs, 2 tabs

  20. Sodium-metal halide and sodium-air batteries.

    Science.gov (United States)

    Ha, Seongmin; Kim, Jae-Kwang; Choi, Aram; Kim, Youngsik; Lee, Kyu Tae

    2014-07-21

    Impressive developments have been made in the past a few years toward the establishment of Na-ion batteries as next-generation energy-storage devices and replacements for Li-ion batteries. Na-based cells have attracted increasing attention owing to low production costs due to abundant sodium resources. However, applications of Na-ion batteries are limited to large-scale energy-storage systems because of their lower energy density compared to Li-ion batteries and their potential safety problems. Recently, Na-metal cells such as Na-metal halide and Na-air batteries have been considered to be promising for use in electric vehicles owing to good safety and high energy density, although less attention is focused on Na-metal cells than on Na-ion cells. This Minireview provides an overview of the fundamentals and recent progress in the fields of Na-metal halide and Na-air batteries, with the aim of providing a better understanding of new electrochemical systems. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Self-trapped holes in alkali silver halide crystals

    International Nuclear Information System (INIS)

    Awano, T.; Ikezawa, M.; Matsuyama, T.

    1995-01-01

    γ-Ray irradiation at 77 K induces defects in M 2 AgX 3 (M=Rb, K and NH 4 ; X=Br and I) crystals. The irradiation induces self-trapped holes of the form of I 0 in the case of alkali silver iodides, and (halogen) 2 - and (halogen) 0 in the case of ammonium silver halides. The (halogen) 0 is weakly coupled with the nearest alkali metal ion or ammonium ion. It is able to be denoted as RbI + , KI + , NH 4 I + or NH 4 Br + . The directions of hole distribution of (halogen) 2 - and (halogen) 0 were different in each case of the alkali silver iodides, ammonium silver halides and mixed crystal of them. The (halogen) 0 decayed at 160 K in annealing process. The (halogen) 2 - was converted into another form of (halogen) 2 - at 250 K and this decayed at 310 K. A formation of metallic layers was observed on the crystal surface parallel with the c-plane of (NH 4 ) 2 AgI 3 irradiated at room temperature. (author)

  2. Nature of the superionic transition in Ag+ and Cu+ halides

    International Nuclear Information System (INIS)

    Keen, D.A.; Hull, S.; Barnes, A.C.; Berastegui, P.; Crichton, W.A.; Madden, P.A.; Tucker, M.G.; Wilson, M.

    2003-01-01

    Silver and copper halides generally display an abrupt (first-order) transition to the superionic state. However, powder diffraction studies and molecular dynamics (MD) simulations of AgI under hydrostatic pressure both indicate that a continuous superionic transition occurs on heating. The gradual onset of the highly conducting state is accompanied by an increasing fraction of dynamic Frenkel defects, a peak in the specific heat and anomalous behavior of the lattice expansion. Similar methods have been employed to investigate the proposed continuous superionic transition between the two ambient pressure face centered cubic phases of CuI. This is difficult to examine experimentally, because the hexagonal β phase exists over a narrow temperature range between the γ (cation ordered) and α (cation disordered) phases. MD simulations performed with the simulation box constrained to remain cubic at all temperatures show that, although limited Cu + Frenkel disorder occurs within γ-CuI, CuI undergoes an abrupt superionic transition at 670 K to the superionic α phase. This is supported by powder neutron diffraction studies of CuI lightly doped with Cs + to prevent stabilization of the β phase. The implications of these results on the phase transitions of other copper and silver halide superionic conductors are discussed

  3. Protonation of octadecylamine Langmuir monolayer by adsorption of halide counterions

    Science.gov (United States)

    Sung, Woongmo; Avazbaeva, Zaure; Lee, Jonggwan; Kim, Doseok

    Langmuir monolayer consisting of octadecylamine (C18H37NH2, ODA) was investigated by heterodyne vibrational sum-frequency generation (HD-VSFG) spectroscopy in conjunction with surface pressure-area (π- A) isotherm, and the result was compared with that from cationic-lipid (DPTAP) Langmuir monolayer. In case of ODA monolayer on pure water, both SF intensity of water OH band and the surface pressure were significantly smaller than those of the DPTAP monolayer implying that only small portion of the amine groups (-NH3+ is protonated in the monolayer. In the presence of sodium halides (NaCl and NaI) in the subphase water, it was found that the sign of Imχ (2) of water OH band remained the same as that of the ODA monolayer on pure water, but there was a substantial increase in the SF amplitude. From this, we propose that surface excess of the halide counterions (Cl- and I-) makes the solution condition near the ODA monolayer/water interface more acidic so that ODA molecules in the monolayer are more positively charged, which works to align the water dipoles at the interface.

  4. Halide salts accelerate degradation of high explosives by zerovalent iron

    International Nuclear Information System (INIS)

    Kim, Jong Sung; Shea, Patrick J.; Yang, Jae E.; Kim, Jang-Eok

    2007-01-01

    Zerovalent iron (Fe 0 , ZVI) has drawn great interest as an inexpensive and effective material to promote the degradation of environmental contaminants. A focus of ZVI research is to increase degradation kinetics and overcome passivation for long-term remediation. Halide ions promote corrosion, which can increase and sustain ZVI reactivity. Adding chloride or bromide salts with Fe 0 (1% w/v) greatly enhanced TNT, RDX, and HMX degradation rates in aqueous solution. Adding Cl or Br salts after 24 h also restored ZVI reactivity, resulting in complete degradation within 8 h. These observations may be attributed to removal of the passivating oxide layer and pitting corrosion of the iron. While the relative increase in degradation rate by Cl - and Br - was similar, TNT degraded faster than RDX and HMX. HMX was most difficult to remove using ZVI alone but ZVI remained effective after five HMX reseeding cycles when Br - was present in solution. - The addition of halide ions promotes the degradation of high explosives by zerovalent iron

  5. 8 CFR 333.2 - Attachment of photographs to documents.

    Science.gov (United States)

    2010-01-01

    ... 8 Aliens and Nationality 1 2010-01-01 2010-01-01 false Attachment of photographs to documents. 333... PHOTOGRAPHS § 333.2 Attachment of photographs to documents. A signed photograph of the applicant must be... portion of the photograph in such a manner as not to obscure the features of the applicant. [56 FR 50495...

  6. Looking for an old aerial photograph

    Science.gov (United States)

    ,

    1997-01-01

    Attempts to photograph the surface of the Earth date from the 1800's, when photographers attached cameras to balloons, kites, and even pigeons. Today, aerial photographs and satellite images are commonplace. The rate of acquiring aerial photographs and satellite images has increased rapidly in recent years. Views of the Earth obtained from aircraft or satellites have become valuable tools to Government resource planners and managers, land-use experts, environmentalists, engineers, scientists, and a wide variety of other users. Many people want historical aerial photographs for business or personal reasons. They may want to locate the boundaries of an old farm or a piece of family property. Or they may want a photograph as a record of changes in their neighborhood, or as a gift. The U.S. Geological Survey (USGS) maintains the Earth Science Information Centers (ESIC?s) to sell aerial photographs, remotely sensed images from satellites, a wide array of digital geographic and cartographic data, as well as the Bureau?s wellknown maps. Declassified photographs from early spy satellites were recently added to the ESIC offerings of historical images. Using the Aerial Photography Summary Record System database, ESIC researchers can help customers find imagery in the collections of other Federal agencies and, in some cases, those of private companies that specialize in esoteric products.

  7. Stephen Marc: Photographer for Our Time

    Science.gov (United States)

    Smith, Toni M. Shorter

    2012-01-01

    It is said that "a picture is worth a thousand words" as visual images can express complex and multilayered ideas. Sometimes photographic imagery is so strong and resonant of certain success, struggles, or events that it becomes key to a community or generation. As historic records, photographs are uniquely able to present not only success and…

  8. 36 CFR 702.4 - Photographs.

    Science.gov (United States)

    2010-07-01

    ... 702.4 Parks, Forests, and Public Property LIBRARY OF CONGRESS CONDUCT ON LIBRARY PREMISES § 702.4 Photographs. (a) The policy set out herein applies to all individuals who are photographing Library of... conditions may include provision for a fee for services rendered consistent with the Library's policies and...

  9. Refined global methyl halide budgets with respect to rapeseed (Brassica napus) by life-cycle measurements

    Science.gov (United States)

    Jiao, Y.; Acdan, J.; Xu, R.; Deventer, M. J.; Rhew, R. C.

    2017-12-01

    A precise quantification of global methyl halide budgets is needed to evaluate the ozone depletion potential of these compounds and to predict future changes of stratospheric ozone. However, the global budgets of methyl halides are not balanced between currently identified and quantified sources and sinks. Our study re-evaluated the methyl bromide budget from global cultivated rapeseed (Brassica napus) through life-cycle flux measurements both in the greenhouse and in the field, yielding a methyl bromide emission rate that scales globally to 1.0 - 1.2 Gg yr-1. While this indicates a globally significant source, it is much smaller than the previously widely cited value of 5 - 6 Gg yr-1(Mead et al., 2008), even taking into account the near tripling of annual global yield of rapeseed since the previous evaluation was conducted. Our study also evaluated the methyl chloride and methyl iodide emission levels from rapeseed, yielding emission rates that scale to 5.4 Gg yr-1 for methyl chloride and 1.8 Gg yr-1 of methyl iodide. The concentrations of the methyl donor SAM (S-adenosyl methionine) and the resultant product SAH (S-Adenosyl-L-homocysteine) were also analyzed to explore their role in biogenic methyl halide formation. Halide gradient incubations showed that the magnitude of methyl halide emissions from rapeseed is highly correlated to soil halide levels, thus raising the concern that the heterogeneity of soil halide contents geographically should be considered when extrapolating to global budget.

  10. Formability of ABX3 (X=F,Cl,Br,I) halide perovskites

    International Nuclear Information System (INIS)

    Li Chonghea; Lu Xionggang; Ding Weizhong; Feng Liming; Gao Yonghui; Guo Ziming

    2008-01-01

    In this study a total of 186 complex halide systems were collected; the formabilities of ABX 3 (X = F, Cl, Br and I) halide perovskites were investigated using the empirical structure map, which was constructed by Goldschmidt's tolerance factor and the octahedral factor. A model for halide perovskite formability was built up. In this model obtained, for all 186 complex halides systems, only one system (CsF-MnF 2 ) without perovskite structure and six systems (RbF-PbF 2 , CsF- BeF 2 , KCl-FeCl 2 , TlI-MnI 2 , RbI-SnI 2 , TlI-PbI 2 ) with perovskite structure were wrongly classified, so its predicting accuracy reaches 96%. It is also indicated that both the tolerance factor and the octahedral factor are a necessary but not sufficient condition for ABX 3 halide perovskite formability, and a lowest limit of the octahedral factor exists for halide perovskite formation. This result is consistent with our previous report for ABO 3 oxide perovskite, and may be helpful to design novel halide materials with the perovskite structure. (orig.)

  11. Energetics of the ruthenium-halide bond in olefin metathesis (pre)catalysts

    KAUST Repository

    Falivene, Laura; Poater, Albert; Cazin, Catherine S J; Slugovc, Christian; Cavallo, Luigi

    2013-01-01

    A DFT analysis of the strength of the Ru-halide bond in a series of typical olefin metathesis (pre)catalysts is presented. The calculated Ru-halide bond energies span the rather broad window of 25-43 kcal mol-1. This indicates that in many systems dissociation of the Ru-halide bond is possible and is actually competitive with dissociation of the labile ligand generating the 14e active species. Consequently, formation of cationic Ru species in solution should be considered as a possible event. © 2013 The Royal Society of Chemistry.

  12. Development of halide copper vapor laser (the characteristics of using Cul)

    International Nuclear Information System (INIS)

    Oouti, Kazumi; Wada, Yukio; Sasao, Nobuyuki

    1990-01-01

    We are developing halide copper vapor laser that is high efficiency and high reputation rate visible laser. Halide copper vapor laser uses halide copper of copper vapor source. It melts low temperature in comporison with metal copper, because laser tube structure is very simple and it can operate easy. This time, we experiment to use Cul for copper vapor source. We resulted maximum output energy 17.8 (W) and maximum efficiency 0.78 (%) when operate condition was reputation rate 30 (kHz), gas pressure 90 (Torr), charging voltage 13 (kV). (author)

  13. An Investigation into Japine Platinum Photographs: William Willis´s Proprietary Paper

    DEFF Research Database (Denmark)

    Vila, Anna; Clark, Matthew L; McCabe, Constance

    2015-01-01

    and are essentially unknown to modern-day scholars who may mistake them as prints with thin binder layers, such as albumen or gelatin. Indeed, the approach to conservation of these photographs may differ from one designed for a traditional platinum print. The parchmentized Japine paper was criticized for its tendency......Analyses of two samples of the commercial platinum photographic paper “Japine” revealed that this trade-name product was sold with a range of surface properties from matte to glossy. An in-depth examination of an unprocessed glossy Japine sample showed a chemically modified surface resulting from...... parchmentization by treatment with sulfuric acid. This treatment results in a thin film of amorphous cellulose on the printing surface, altering its visual appearance and wet strength. Photographers selected this paper due to its aesthetic qualities. However, such papers have never been characterized...

  14. Agreement between radiographic and photographic trabecular patterns

    International Nuclear Information System (INIS)

    Korstjens, C.M.; Geraets, W.G.M.; Stelt, P.F. van der; Spruijt, R.J.; Mosekilde, L.

    1998-01-01

    Purpose: It has been hypothesized that photographs can facilitate the interpretation of the radiographic characteristics of trabecular bone. The reliability of these photographic and radiographic approaches has been determined, as have various agreements between the two approaches and their correlations with biomechanical characteristics. Material and Methods: Fourteen vertebral bodies were obtained at autopsy from 6 women and 8 men aged 22-76 years. Photographs (n=28) and radiographs (n=28) were taken of midsagittal slices from the third lumbar vertebra. The radiographs and photographs were digitized and the geometric properties of the trabecular architecture were then determined with a digital images analysis technique. Information on the compressive strength and ash density of the vertebral body was also available. Results: The geometric properties of both radiographs and photographs could be measured with a high degree of reliability (Cronbach's α>0.85). Agreement between the radiographic and photographic approaches was mediocre as only the radiographic measurements showed insignificant correlations (p<0.05) with the biomechanical characteristics. We suggest that optical phenomena may result in the significant correlations between the photographs and the biomechanical characteristics. Conclusion: For digital image processing, radiography offers a superior description of the architecture of trabecular bone to that offered by photography. (orig.)

  15. Agreement between radiographic and photographic trabecular patterns

    Energy Technology Data Exchange (ETDEWEB)

    Korstjens, C.M.; Geraets, W.G.M.; Stelt, P.F. van der [Dept. of Oral Radiology, Academic Centre for Dentistry, Amsterdam (Netherlands); Spruijt, R.J. [Div. of Psychosocial Research and Epidemiology, Netherlands Cancer Inst., Amsterdam (Netherlands); Mosekilde, L. [Dept. of Cell Biology, Univ. of Aarhus (Denmark)

    1998-11-01

    Purpose: It has been hypothesized that photographs can facilitate the interpretation of the radiographic characteristics of trabecular bone. The reliability of these photographic and radiographic approaches has been determined, as have various agreements between the two approaches and their correlations with biomechanical characteristics. Material and Methods: Fourteen vertebral bodies were obtained at autopsy from 6 women and 8 men aged 22-76 years. Photographs (n=28) and radiographs (n=28) were taken of midsagittal slices from the third lumbar vertebra. The radiographs and photographs were digitized and the geometric properties of the trabecular architecture were then determined with a digital images analysis technique. Information on the compressive strength and ash density of the vertebral body was also available. Results: The geometric properties of both radiographs and photographs could be measured with a high degree of reliability (Cronbach`s {alpha}>0.85). Agreement between the radiographic and photographic approaches was mediocre as only the radiographic measurements showed insignificant correlations (p<0.05) with the biomechanical characteristics. We suggest that optical phenomena may result in the significant correlations between the photographs and the biomechanical characteristics. Conclusion: For digital image processing, radiography offers a superior description of the architecture of trabecular bone to that offered by photography. (orig.)

  16. Metal halide arc discharge lamp having short arc length

    Science.gov (United States)

    Muzeroll, Martin E. (Inventor)

    1994-01-01

    A metal halide arc discharge lamp includes a sealed light-transmissive outer jacket, a light-transmissive shroud located within the outer jacket and an arc tube assembly located within the shroud. The arc tube assembly includes an arc tube, electrodes mounted within the arc tube and a fill material for supporting an arc discharge. The electrodes have a spacing such that an electric field in a range of about 60 to 95 volts per centimeter is established between the electrodes. The diameter of the arc tube and the spacing of the electrodes are selected to provide an arc having an arc diameter to arc length ratio in a range of about 1.6 to 1.8. The fill material includes mercury, sodium iodide, scandium tri-iodide and a rare gas, and may include lithium iodide. The lamp exhibits a high color rendering index, high lumen output and high color temperature.

  17. Structure of some complex halides of uranium(III)

    International Nuclear Information System (INIS)

    Volkov, V.A.; Suglobova, I.G.; Chirkst, D.E.

    1987-01-01

    Polycrystals of some halide complexes of uranium(III) were obtained and investigated by x-ray diffraction. The M 2 UCl 5 compounds (M = K, Rb) are isostructural with K 2 PrCl 5 ; RbU 2 Cl 7 is of the same type as RbDy 2 Cl 7 or KDy 2 Cl 7 . The coordination number of the uranium is 7. The M 2 UBr 5 compounds (M = K-Cs) are isostructural with Cs 2 DyCl 5 , and the coordination number of the uranium is 6. Rb 2 NaUCl 6 is a 12L-hexagonal polytype, the structural analog of Cs 2 NaCrF 6 . The most characteristic coordination number of uranium in the UHal 3 -MHal systems is 8 for Hal = F, 7 for Hal = Cl, and 6 for Hal = Br

  18. Phase-resolved response of a metal-halide lamp

    International Nuclear Information System (INIS)

    Flikweert, A J; Beks, M L; Nimalasuriya, T; Kroesen, G M W; Van der Mullen, J J A M; Stoffels, W W

    2009-01-01

    The metal-halide (MH) lamp sometimes shows unwanted colour segregation, caused by a combination of convection and diffusion. In the past we investigated the lamp, running on a switched dc ballast of 120 Hz, using a dc approximation for the distribution of the radiating species. Here we present phase-resolved intensity measurements to verify this approximation. The MH lamp contains Hg as buffer gas and DyI 3 as salt additive; we measure the light emitted by Dy and by Hg atoms. An intensity fluctuation of ∼25% close to the electrodes is found only. The observed fluctuations are explained by the cataphoresis effect and temperature fluctuations; the time scales are in the same order. Furthermore, measurements at higher gravity in a centrifuge (up to 10g) show that the effect becomes smaller at increasing gravity levels. From these results it is concluded that a dc approximation, which is generally assumed by lamp developers, is allowed for this MH lamp.

  19. Ultraviolet optical absorption of alkali cyanides and alkali halide cyanides

    International Nuclear Information System (INIS)

    Souza Camargo Junior, S.A. de.

    1982-09-01

    The ultraviolet absorption spectra of alkali cyanide and mixed alkali halide cyanide crystals were measured at temperatures ranging from 300K down to 4.2K. A set of small absorption peaks was observed at energies near 6 eV and assigned to parity forbidden X 1 Σ + →a' 3 Σ + transitions of the CN - molecular ions. It was observed that the peak position depends on the alkali atom while the absorption cross section strongly depends on the halogen and on the CN - concentration of the mixed crystals. These effects are explained in terms of an interaction between the triplet molecular excitons and charge transfer excitons. The experimental data were fit with a coupling energy of a few meV. The coupling mechanism is discussed and it is found to be due to the overlap between the wave functions of the two excitations. (Author) [pt

  20. Absorption lineshape of FA centers in alkali halides

    International Nuclear Information System (INIS)

    Baldacchini, G.; Giovenale, E.; De Matteis, F.; Scacco, A.; Somma, F.; Grassano, U.M.

    1988-01-01

    The line shape of the absorption bands of F A centers in alkali halides have been studied for the first time. The new method used for this investigation is based on the determination of the overlap between the F A1 and F A2 bands from luminescence measurements. The experimental results have been compared with calculated values deduced from the theoretical F A bands of different shapes. For both F A (I) centers in KCl:Na + and F A (II) centers in KCl:Li + and RbCl:Li + the absorption lineshape at low temperature is much closer to a sum of two Lorentzian curves than that of two Gaussian or Poissonian bands. This results shows an unexpected difference with the F centers, whose absorption lineshape is known to be Poissonian at the same temperatures

  1. White-Light Emission from Layered Halide Perovskites.

    Science.gov (United States)

    Smith, Matthew D; Karunadasa, Hemamala I

    2018-03-20

    With nearly 20% of global electricity consumed by lighting, more efficient illumination sources can enable massive energy savings. However, effectively creating the high-quality white light required for indoor illumination remains a challenge. To accurately represent color, the illumination source must provide photons with all the energies visible to our eye. Such a broad emission is difficult to achieve from a single material. In commercial white-light sources, one or more light-emitting diodes, coated by one or more phosphors, yield a combined emission that appears white. However, combining emitters leads to changes in the emission color over time due to the unequal degradation rates of the emitters and efficiency losses due to overlapping absorption and emission energies of the different components. A single material that emits broadband white light (a continuous emission spanning 400-700 nm) would obviate these problems. In 2014, we described broadband white-light emission upon near-UV excitation from three new layered perovskites. To date, nine white-light-emitting perovskites have been reported by us and others, making this a burgeoning field of study. This Account outlines our work on understanding how a bulk material, with no obvious emissive sites, can emit every color of the visible spectrum. Although the initial discoveries were fortuitous, our understanding of the emission mechanism and identification of structural parameters that correlate with the broad emission have now positioned us to design white-light emitters. Layered hybrid halide perovskites feature anionic layers of corner-sharing metal-halide octahedra partitioned by organic cations. The narrow, room-temperature photoluminescence of lead-halide perovskites has been studied for several decades, and attributed to the radiative recombination of free excitons (excited electron-hole pairs). We proposed that the broad white emission we observed primarily stems from exciton self-trapping. Here, the

  2. The Effect of Radiation "Memory" in Alkali-Halide Crystals

    Science.gov (United States)

    Korovkin, M. V.; Sal'nikov, V. N.

    2017-01-01

    The exposure of the alkali-halide crystals to ionizing radiation leads to the destruction of their structure, the emergence of radiation defects, and the formation of the electron and hole color centers. Destruction of the color centers upon heating is accompanied by the crystal bleaching, luminescence, and radio-frequency electromagnetic emission (REME). After complete thermal bleaching of the crystal, radiation defects are not completely annealed, as the electrons and holes released from the color centers by heating leave charged and locally uncompensated defects. Clusters of these "pre centers" lead to electric microheterogeneity of the crystal, the formation of a quasi-electret state, and the emergence of micro-discharges accompanied by radio emission. The generation of REME associated with residual defectiveness, is a manifestation of the effect of radiation "memory" in dielectrics.

  3. Coulometric thermometric titration of halides in molten calcium nitrate tetrahydrate.

    Science.gov (United States)

    Zsigrai, I J; Bartusz, D B

    1983-01-01

    A method for coulometric thermometric precipitation titrations of chloride, bromide and iodide in molten calcium nitrate tetrahydrate at 55 degrees with coulometrically generated silver ions has been developed. The change in temperature during the titration is followed with the aid of a thermistor bridge coupled to a recorder. To minimize the temperature effect of the passage of current through the melt, two thermistors are connected in opposition in the bridge, with one in the anodic and the other in the cathodic cell compartment. Amounts of 62-80 mumole of halide have been determined with relative error below 0.4% and relative standard deviation less than 2.7%. The relative error in determination of 40 mumole of iodide was + 2%.

  4. Metal Halide Perovskite Single Crystals: From Growth Process to Application

    Directory of Open Access Journals (Sweden)

    Shuigen Li

    2018-05-01

    Full Text Available As a strong competitor in the field of optoelectronic applications, organic-inorganic metal hybrid perovskites have been paid much attention because of their superior characteristics, which include broad absorption from visible to near-infrared region, tunable optical and electronic properties, high charge mobility, long exciton diffusion length and carrier recombination lifetime, etc. It is noted that perovskite single crystals show remarkably low trap-state densities and long carrier diffusion lengths, which are even comparable with the best photovoltaic-quality silicon, and thus are expected to provide better optoelectronic performance. This paper reviews the recent development of crystal growth in single-, mixed-organic-cation and fully inorganic halide perovskite single crystals, in particular the solution approach. Furthermore, the application of metal hybrid perovskite single crystals and future perspectives are also highlighted.

  5. Gas phase chromatography of halides of elements 104 and 105

    International Nuclear Information System (INIS)

    Tuerler, A.; Gregorich, K.E.; Czerwinski, K.R.; Hannink, N.J.; Henderson, R.A.; Hoffman, D.C.; Kacher, C.D.; Kadkhodayan, B.; Kreek, S.A.; Lee, D.M.; Leyba, J.D.; Nurmia, M.J.; Gaeggeler, H.W.; Jost, D.T.; Kovacs, J.; Scherer, U.W.; Vermeulen, D.; Weber, A.; Barth, H.; Gober, M.K.; Kratz, J.V.; Bruechle, W.; Schaedel, M.; Schimpf, E.; Gober, M.K.; Kratz, J.V.; Zimmermann, H.P.

    1991-04-01

    On-line isothermal gas phase chromatography was used to study halides of 261 104 (T 1/2 = 65 s) and 262,263 105 (T 1/2 = 34 s and 27 s) produced an atom-at-a time via the reactions 248 Cm( 18 O, 5n) and 249 Bk( 18 O, 5n, 4n), respectively. Using HBr and HCl gas as halogenating agents, we were able to produce volatile bromides and chlorides of the above mentioned elements and study their behavior compared to their lighter homologs in Groups 4 or 5 of the periodic table. Element 104 formed more volatile bromides than its homolog Hf. In contrast, element 105 bromides were found to be less volatile than the bromides of the group 5 elements Nb and Ta. Both 104 and Hf chlorides were observed to be more volatile than their respective bromides. 31 refs., 8 figs

  6. M-center growth in alkali halides: computer simulation

    International Nuclear Information System (INIS)

    Aguilar, M.; Jaque, F.; Agullo-Lopez, F.

    1983-01-01

    The heterogeneous interstitial nucleation model previously proposed to explain F-center growth curves in irradiated alkali halides has been extended to account for M-center kinetics. The interstitials produced during the primary irradiation event are assumed to be trapped at impurities and interstitial clusters or recombine with F and M centers. For M-center formation two cases have been considered: (a) diffusion and aggregation of F centers, and (b) statistical generation and pairing of F centers. Process (b) is the only one consistent with the quadratic relationship between M and F center concentrations. However, to account for the F/M ratios experimentally observed as well as for the role of dose-rate, a modified statistical model involving random creation and association of F + -F pairs has been shown to be adequate. (author)

  7. Irradiation damage of alkali halide crystals during positron bombardment

    International Nuclear Information System (INIS)

    Arefiev, K.P.; Arefiev, V.P.; Vorobiev, S.A.

    1978-01-01

    The bleaching effect of positron irradiation of KCl and KBr single crystals previously coloured with electrons or protons was investigated. Positrons injection in the coloured alkali halide samples reduced the F-centres concentration considerably. For KCl crystals thicker than the positrons range the appearance of additional bands in the absorption spectra is noticeable. The experimental data show that the bleaching phenomenon should be observed merely throughout the positron exposure both for irradiated and non-irradiated regions of the sample. Irradiation effects, due to positron source, on the peak counting rate of (γ-γ) angular correlation in KCl crystals under applied magnetic field were also investigated. The growth of peak counting rate shows the increase of positronium-like states formation near defects of cation sublattice. (author)

  8. [Natural head position's reproducibility on photographs].

    Science.gov (United States)

    Eddo, Marie-Line; El Hayeck, Émilie; Hoyeck, Maha; Khoury, Élie; Ghoubril, Joseph

    2017-12-01

    The purpose of this study is to evaluate the reproducibility of natural head position with time on profile photographs. Our sample is composed of 96 students (20-30 years old) at the department of dentistry of Saint Joseph University in Beirut. Two profile photographs were taken in natural head position about a week apart. No significant differences were found between T0 and T1 (E = 1.065°). Many studies confirmed this reproducibility with time. Natural head position can be adopted as an orientation for profile photographs in orthodontics. © EDP Sciences, SFODF, 2017.

  9. The Photoshop CS4 Companion for Photographers

    CERN Document Server

    Story, Derrick

    2009-01-01

    "Derrick shows that Photoshop can be friendly as well as powerful. In part, he does that by focusing photographers on the essential steps of an efficient workflow. With this guide in hand, you'll quickly learn how to leverage Photoshop CS4's features to organize and improve your pictures."-- John Nack, Principal Product Manager, Adobe Photoshop & BridgeMany photographers -- even the pros -- feel overwhelmed by all the editing options Photoshop provides. The Photoshop CS4 Companion for Photographers pares it down to only the tools you'll need most often, and shows you how to use those tools as

  10. Phase space investigation of the lithium amide halides

    Energy Technology Data Exchange (ETDEWEB)

    Davies, Rosalind A. [Hydrogen Storage Chemistry Group, School of Chemistry, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom); Hydrogen and Fuel Cell Group, School of Chemical Engineering, University of Birmingham, Edgbaston B15 2TT (United Kingdom); Hewett, David R.; Korkiakoski, Emma [Hydrogen Storage Chemistry Group, School of Chemistry, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom); Thompson, Stephen P. [Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0QX (United Kingdom); Anderson, Paul A., E-mail: p.a.anderson@bham.ac.uk [Hydrogen Storage Chemistry Group, School of Chemistry, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom)

    2015-10-05

    Highlights: • The lower limits of halide incorporation in lithium amide have been investigated. • The only amide iodide stoichiometry observed was Li{sub 3}(NH{sub 2}){sub 2}I. • Solid solutions were observed in both the amide chloride and amide bromide systems. • A 46% reduction in chloride content resulted in a new phase: Li{sub 7}(NH{sub 2}){sub 6}Cl. • New low-chloride phase maintained improved H{sub 2} desorption properties of Li{sub 4}(NH{sub 2}){sub 3}Cl. - Abstract: An investigation has been carried out into the lower limits of halide incorporation in lithium amide (LiNH{sub 2}). It was found that the lithium amide iodide Li{sub 3}(NH{sub 2}){sub 2}I was unable to accommodate any variation in stoichiometry. In contrast, some variation in stoichiometry was accommodated in Li{sub 7}(NH{sub 2}){sub 6}Br, as shown by a decrease in unit cell volume when the bromide content was reduced. The amide chloride Li{sub 4}(NH{sub 2}){sub 3}Cl was found to adopt either a rhombohedral or a cubic structure depending on the reaction conditions. Reduction in chloride content generally resulted in a mixture of phases, but a new rhombohedral phase with the stoichiometry Li{sub 7}(NH{sub 2}){sub 6}Cl was observed. In comparison to LiNH{sub 2}, this new low-chloride phase exhibited similar improved hydrogen desorption properties as Li{sub 4}(NH{sub 2}){sub 3}Cl but with a much reduced weight penalty through addition of chloride. Attempts to dope lithium amide with fluoride ions have so far proved unsuccessful.

  11. Dehalogenation of aromatic halides by polyaniline/zero-valent iron composite nanofiber: Kinetics and mechanisms

    CSIR Research Space (South Africa)

    Giri, S

    2016-03-01

    Full Text Available Dehalogenation of aryl halides was demonstrated using polyaniline/zero valent iron composite nanofiber (termed as PANI/Fe0) as a cheap, efficient and environmentally friendly heterogeneous catalyst. The catalyst was prepared via rapid mixing...

  12. Impact of the organic halide salt on final perovskite composition for photovoltaic applications

    KAUST Repository

    Moore, David T.; Sai, Hiroaki; Wee Tan, Kwan; Estroff, Lara A.; Wiesner, Ulrich

    2014-01-01

    The methylammonium lead halide perovskites have shown significant promise as a low-cost, second generation, photovoltaic material.Despite recent advances, however, there are still a number of fundamental aspects of their formation as well

  13. The Role of Surface Tension in the Crystallization of Metal Halide Perovskites

    KAUST Repository

    Zhumekenov, Ayan A.; Burlakov, Victor M.; Saidaminov, Makhsud I.; Alofi, Abdulilah; Haque, Mohammed; Turedi, Bekir; Davaasuren, Bambar; Dursun, Ibrahim; Cho, Nam Chul; El-Zohry, Ahmed M.; de Bastiani, Michele; Giugni, Andrea; Torre, Bruno; Di Fabrizio, Enzo M.; Mohammed, Omar F.; Rothenberger, Alexander; Wu, Tao; Goriely, Alain; Bakr, Osman

    2017-01-01

    The exciting intrinsic properties discovered in single crystals of metal halide perovskites still await their translation into optoelectronic devices. The poor understanding and control of the crystallization process of these materials are current

  14. NEW THIO S2- ADDUCTS WITH ANTIMONY (III AND V HALIDE: SYNTHESIS AND INFRARED STUDY

    Directory of Open Access Journals (Sweden)

    HASSAN ALLOUCH

    2013-12-01

    Full Text Available Five new S2- adducts with SbIII and SbV halides have been synthesized and studied by infrared. Discrete structures have been suggested, the environment around the antimony being tetrahedral, trigonal bipyramidal or octahedral.

  15. Growth and Characterization of PDMS-Stamped Halide Perovskite Single Microcrystals

    NARCIS (Netherlands)

    Khoram, P.; Brittman, S.; Dzik, W.I.; Reek, J.N.H.; Garneett, E.C.

    2016-01-01

    Recently, halide perovskites have attracted considerable attention for optoelectronic applications, but further progress in this field requires a thorough understanding of the fundamental properties of these materials. Studying perovskites in their single-crystalline form provides a model system for

  16. Solution enthalpies of alkali metal halides in water and heavy water mixtures with dimethyl sulfoxide

    International Nuclear Information System (INIS)

    Egorov, G.I.

    1994-01-01

    Solution enthalpies of CsF, LiCl, NaI, CsI and some other halides of alkali metals and tetrabutylammonium have been measured by the method of calorimetry. Standard solution enthalpies of all alkali metals (except rubidium) halides in water and heavy water mixtures with dimethylsulfoxide at 298.15 K have been calculated. Isotopic effects in solvation enthalpy of the electrolytes mentioned in aqueous solutions of dimethylsulfoxide have been discussed. 29 refs., 2 figs., 4 tabs

  17. Influence of electrode, buffer gas and control gear on metal halide lamp performance

    International Nuclear Information System (INIS)

    Lamouri, A; Naruka, A; Sulcs, J; Varanasi, C V; Brumleve, T R

    2005-01-01

    In this paper the influence of electrode composition, buffer gas fill pressure and control gear on the performance of metal halide lamps is investigated. It is shown that pure tungsten electrodes improve lumen maintenance and reduce voltage rise over lamp life. An optimum buffer gas fill pressure condition is discovered which allows for reduced electrode erosion during lamp starting as well as under normal operating conditions. Use of electronic control gear is shown to improve the performance of metal halide lamps

  18. Transfer Hydro-dehalogenation of Organic Halides Catalyzed by Ruthenium(II) Complex.

    Science.gov (United States)

    You, Tingjie; Wang, Zhenrong; Chen, Jiajia; Xia, Yuanzhi

    2017-02-03

    A simple and efficient Ru(II)-catalyzed transfer hydro-dehalogenation of organic halides using 2-propanol solvent as the hydride source was reported. This methodology is applicable for hydro-dehalogenation of a variety of aromatic halides and α-haloesters and amides without additional ligand, and quantitative yields were achieved in many cases. The potential synthetic application of this method was demonstrated by efficient gram-scale transformation with catalyst loading as low as 0.5 mol %.

  19. Organometallic halide perovskite single crystals having low deffect density and methods of preparation thereof

    KAUST Repository

    Bakr, Osman M.

    2016-02-18

    The present disclosure presents a method of making a single crystal organometallic halide perovskites, with the formula: AMX3, wherein A is an organic cation, M is selected from the group consisting of: Pb, Sn, Cu, Ni, Co, Fe, Mn, Pd, Cd, Ge, and Eu, and X is a halide. The method comprises the use of two reservoirs containing different precursors and allowing the vapor diffusion from one reservoir to the other one. A solar cell comprising said crystal is also disclosed.

  20. The thermo-elastic instability model of melting of alkali halides in the Debye approximation

    Science.gov (United States)

    Owens, Frank J.

    2018-05-01

    The Debye model of lattice vibrations of alkali halides is used to show that there is a temperature below the melting temperature where the vibrational pressure exceeds the electrostatic pressure. The onset temperature of this thermo-elastic instability scales as the melting temperature of NaCl, KCl, and KBr, suggesting its role in the melting of the alkali halides in agreement with a previous more rigorous model.

  1. Broadly tunable metal halide perovskites for solid-state light-emission applications

    OpenAIRE

    Adjokatse, Sampson; Fang, Hong-Hua; Loi, Maria Antonietta

    2017-01-01

    The past two years have witnessed heightened interest in metal-halide perovskites as promising optoelectronic materials for solid-state light emitting applications beyond photovoltaics. Metal-halide perovskites are low-cost solution-processable materials with excellent intrinsic properties such as broad tunability of bandgap, defect tolerance, high photoluminescence quantum efficiency and high emission color purity (narrow full-width at half maximum). In this review, the photophysical propert...

  2. Cation-Dependent Light-Induced Halide Demixing in Hybrid Organic-Inorganic Perovskites

    OpenAIRE

    Sutter-Fella, CM; Ngo, QP; Cefarin, N; Gardener, K; Tamura, N; Stan, CV; Drisdell, WS; Javey, A; Toma, FM; Sharp, ID

    2018-01-01

    © 2018 American Chemical Society. Mixed cation metal halide perovskites with increased power conversion efficiency, negligible hysteresis, and improved long term stability under illumination, moisture, and thermal stressing have emerged as promising compounds for photovoltaic and optoelectronic applications. Here, we shed light on photo-induced halide demixing using in-situ photoluminescence spectroscopy and in-situ synchrotron X-ray diffraction (XRD) to directly compare the evolution of comp...

  3. Metal halides vapor lasers with inner reactor and small active volume.

    Science.gov (United States)

    Shiyanov, D. V.; Sukhanov, V. B.; Evtushenko, G. S.

    2018-04-01

    Investigation of the energy characteristics of copper, manganese, lead halide vapor lasers with inner reactor and small active volume 90 cm3 was made. The optimal operating pulse repetition rates, temperatures, and buffer gas pressure for gas discharge tubes with internal and external electrodes are determined. Under identical pump conditions, such systems are not inferior in their characteristics to standard metal halide vapor lasers. It is shown that the use of a zeolite halogen generator provides lifetime laser operation.

  4. MAPbI2.9-xBrxCl0.1 hybrid halide perovskites: Shedding light on the effect of chloride and bromide ions on structural and photoluminescence properties

    Science.gov (United States)

    Atourki, Lahoucine; Vega, Erika; Marí, Bernabé; Mollar, Miguel; Ait Ahsaine, Hassan; Bouabid, Khalid; Ihlal, Ahmed

    2016-12-01

    The optical and structural properties of CH3NH3PbI3 can be adjusted by introducing other extrinsic ions such as chloride and bromide. In this work, mixed bromide iodide lead perovskites with a 10% fraction of chloride were prepared from methylamine, lead nitrate and the corresponding hydro acid (X = I, Br, Cl). The effect of bromide and chloride incorporation on different properties of perovskite thin film was investigated. The Pawley fit method indicates the formation of the iodide halide MAPbI3 Pm-3 m cubic phase for x = 0 and the tetragonal P4/mmm phase for x ≥ 0.3. All deposited films showed a strong absorbance in the UV-vis range. The band gap values were estimated from absorbance measurements. It was found that the onset of the absorption edge for MAPbI2.9-xBrxCl0.1 thin film perovskites ranges between 1.60 and 1.80 eV. Moreover, it was found that both Cl and Br affect the PL emission of the mixed halide lead perovskite, the MAPbI2.9-xBrxCl0.1 films displayed intermediate values from 730 nm (MAPbI2.2Br0.7Cl0.1) to 770 nm (MAPbI2.6Br0.3Cl0.1).

  5. Receptor saturation in roentgen films

    Energy Technology Data Exchange (ETDEWEB)

    Strid, K G; Reichmann, S [Sahlgrenska Sjukhuset, Goeteborg (Sweden)

    1980-01-01

    Roentgen-film recording of small object details of low attenuation differences (e.g. pulmonary vessels) is regularly seen to be impaired when the film is exposed to yield high values of optical density (D). This high-density failure is due to receptor saturation, which implies that at high exposure values most silver halide grains of the film are made developable, leaving few grains available to receive additional informative photons. The receptor saturation is analysed by means of a mathematical model of a non-screen film yielding Dsub(max) = 2.0. Optimum recording, defined by maximum signal-to-noise ratio in the image, is found at D approximately 0.64, corresponding to, on an average, 1.6 photons absorbed per grain. On the other hand, maximum contrast occurs at D approximately 1.4, where, on the average, 3.6 photons are absorbed per grain. The detective quantum efficiency of the film, i.e. the fraction of the photons actually contributing to the information content of the image, drops from 41 per cent at maximum signal-to-noise ratio to a mere 10 per cent at maximum contrast.

  6. Special photographic emulsions for high LET dosimetry

    International Nuclear Information System (INIS)

    Katz, R.

    1978-12-01

    The purpose of these investigations into photographic emulsion dosimetry is to attempt to use the photographic emulsion to mimic the response of human tissues to high LET radiations. The program therefore requires that a systematic understanding of the response of mammalian cells to ionizing radiations be achieved. We have been concerned with differences in RBE and in radiation response to both high and LET radiations, and in the interrelationship between observations with these different radiations

  7. Organometal Halide Perovskite Solar Absorbers and Ferroelectric Nanocomposites for Harvesting Solar Energy

    Science.gov (United States)

    Hettiarachchi, Chaminda Lakmal

    Organometal halide perovskite absorbers such as methylammonium lead iodide chloride (CH3NH3PbI3-xClx), have emerged as an exciting new material family for photovoltaics due to its appealing features that include suitable direct bandgap with intense light absorbance, band gap tunability, ultra-fast charge carrier generation, slow electron-hole recombination rates, long electron and hole diffusion lengths, microsecond-long balanced carrier mobilities, and ambipolarity. The standard method of preparing CH3NH3PbI3-xClx perovskite precursors is a tedious process involving multiple synthesis steps and, the chemicals being used (hydroiodic acid and methylamine) are quite expensive. This work describes a novel, single-step, simple, and cost-effective solution approach to prepare CH3NH3PbI3-xClx thin films by the direct reaction of the commercially available CH3NH 3Cl (or MACl) and PbI2. A detailed analysis of the structural and optical properties of CH3NH3PbI3-xCl x thin films deposited by aerosol assisted chemical vapor deposition is presented. Optimum growth conditions have been identified. It is shown that the deposited thin films are highly crystalline with intense optical absorbance. Charge carrier separation of these thin films can be enhanced by establishing a local internal electric field that can reduce electron-hole recombination resulting in increased photo current. The intrinsic ferroelectricity in nanoparticles of Barium Titanate (BaTiO3 -BTO) embedded in the solar absorber can generate such an internal field. A hybrid structure of CH3NH 3PbI3-xClx perovskite and ferroelectric BTO nanocomposite FTO/TiO2/CH3NH3PbI3-xClx : BTO/P3HT/Cu as a new type of photovoltaic device is investigated. Aerosol assisted chemical vapor deposition process that is scalable to large-scale manufacturing was used for the growth of the multilayer structure. TiO 2 and P3HT with additives were used as ETL and HTL respectively. The growth process of the solar absorber layer includes the

  8. Observation of vapor pressure enhancement of rare-earth metal-halide salts in the temperature range relevant to metal-halide lamps

    Energy Technology Data Exchange (ETDEWEB)

    Curry, J. J.; Henins, A.; Hardis, J. E. [National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States); Estupinan, E. G. [Osram Sylvania Inc., Beverly, Massachusetts 01915 (United States); Lapatovich, W. P. [Independent Consultant, 51 Pye Brook Lane, Boxford, Massachusetts 01921 (United States); Shastri, S. D. [Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439 (United States)

    2012-02-20

    Total vapor-phase densities of Dy in equilibrium with a DyI{sub 3}/InI condensate and Tm in equilibrium with a TmI{sub 3}/TlI condensate have been measured for temperatures between 900 K and 1400 K. The measurements show strong enhancements in rare-earth vapor densities compared to vapors in equilibrium with the pure rare-earth metal-halides. The measurements were made with x-ray induced fluorescence on the sector 1-ID beam line at the Advanced Photon Source. The temperature range and salt mixtures are relevant to the operation of metal-halide high-intensity discharge lamps.

  9. Development of new methodology for dose calculation in photographic dosimetry

    International Nuclear Information System (INIS)

    Daltro, T.F.L.; Campos, L.L.; Perez, H.E.B.

    1996-01-01

    The personal dosemeter system of IPEN is based on film dosimetry. Personal doses at IPEN are mainly due to X or gamma radiation. The use of personal photographic dosemeters involves two steps: firstly, data acquisition including their evaluation with respect to the calibration quantity and secondly, the interpretation of the data in terms of effective dose. The effective dose was calculated using artificial intelligence techniques by means of neural network. The learning of the neural network was performed by taking the readings of optical density as a function of incident energy and exposure from the calibration curve. The obtained output in the daily grind is the mean effective energy and the effective dose. (author)

  10. Development of new methodology for dose calculation in photographic dosimetry

    International Nuclear Information System (INIS)

    Daltro, T.F.L.

    1994-01-01

    A new methodology for equivalent dose calculations has been developed at IPEN-CNEN/SP to be applied at the Photographic Dosimetry Laboratory using artificial intelligence techniques by means of neutral network. The research was orientated towards the optimization of the whole set of parameters involves in the film processing going from the irradiation in order to obtain the calibration curve up to the optical density readings. The learning of the neutral network was performed by taking the readings of optical density from calibration curve as input and the effective energy and equivalent dose as output. The obtained results in the intercomparison show an excellent agreement with the actual values of dose and energy given by the National Metrology Laboratory of Ionizing Radiation. (author)

  11. Development of new methodology for dose calculation in photographic dosimetry

    International Nuclear Information System (INIS)

    Daltro, T.F.L.; Campos, L.L.

    1994-01-01

    A new methodology for equivalent dose calculation has been developed at IPEN-CNEN/SP to be applied at the Photographic Dosimetry Laboratory using artificial intelligence techniques by means of neural network. The research was oriented towards the optimization of the whole set of parameters involved in the film processing going from the irradiation in order to obtain the calibration curve up to the optical density readings. The learning of the neural network was performed by taking readings of optical density from calibration curve as input and the effective energy and equivalent dose as output. The obtained results in the intercomparison show an excellent agreement with the actual values of dose and energy given by the National Metrology Laboratory of Ionizing Radiation

  12. 44 CFR 15.12 - Photographs and other depictions.

    Science.gov (United States)

    2010-10-01

    ... 44 Emergency Management and Assistance 1 2010-10-01 2010-10-01 false Photographs and other... NATIONAL EMERGENCY TRAINING CENTER § 15.12 Photographs and other depictions. (a) Photographs and other depictions at Mt. Weather. We prohibit taking photographs and making notes, sketches, or diagrams of...

  13. 8 CFR 1236.5 - Fingerprints and photographs.

    Science.gov (United States)

    2010-01-01

    ... 8 Aliens and Nationality 1 2010-01-01 2010-01-01 false Fingerprints and photographs. 1236.5... ORDERED REMOVED Detention of Aliens Prior to Order of Removal § 1236.5 Fingerprints and photographs. Every... photographed. Such fingerprints and photographs shall be made available to Federal, State, and local law...

  14. 8 CFR 333.1 - Description of required photographs.

    Science.gov (United States)

    2010-01-01

    ... 8 Aliens and Nationality 1 2010-01-01 2010-01-01 false Description of required photographs. 333.1 Section 333.1 Aliens and Nationality DEPARTMENT OF HOMELAND SECURITY NATIONALITY REGULATIONS PHOTOGRAPHS § 333.1 Description of required photographs. (a) Every applicant required to furnish photographs of...

  15. Photographing magnetic fields in superconductors

    International Nuclear Information System (INIS)

    Harrison, R.B.; Wright, L.S.

    Magneto-optic techniques coupled with high-speed photography are being used to study the destruction of superconductivity by a magnetic field. The phenomenon of superconductivity will be introduced with emphasis placed on the properties of type I and type II superconductors in a magnetic field. The Faraday effect and its application to the study of the penetration of magnetic fields into these superconductors will be described; the relative effectiveness of some types of paramagnetic glass will be demonstrated. A number of cinefilms will be shown to illustrate the versatility of the magneto-optic method for observing flux motion and patterns. The analysis of data obtained from a high speed film (10,200 fps) of a flux jump in Nb-Zr will be presented and discussed

  16. Magnetic properties of nickel halide hydrates including deuteration effects

    Energy Technology Data Exchange (ETDEWEB)

    DeFotis, G.C., E-mail: gxdefo@wm.edu [Chemistry Department, College of William & Mary, Williamsburg, VA, 23187 United States (United States); Van Dongen, M.J.; Hampton, A.S.; Komatsu, C.H.; Trowell, K.T.; Havas, K.C.; Davis, C.M.; DeSanto, C.L. [Chemistry Department, College of William & Mary, Williamsburg, VA, 23187 United States (United States); Hays, K.; Wagner, M.J. [Chemistry Department, George Washington University, Washington, DC, 20052 United States (United States)

    2017-01-01

    Magnetic measurements on variously hydrated nickel chlorides and bromides, including deuterated forms, are reported. Results include locations and sizes of susceptibility maxima, T{sub max} and χ{sub max}, ordering temperatures T{sub c}, Curie constants and Weiss theta in the paramagnetic regime, and primary and secondary exchange interactions from analysis of low temperature data. For the latter a 2D Heisenberg model augmented by interlayer exchange in a mean-field approximation is applied. Magnetization data to 16 kG as a function of temperature show curvature and hysteresis characteristics quite system dependent. For four materials high field magnetization data to 70 kG at 2.00 K are also obtained. Comparison is made with theoretical relations for spin-1 models. Trends are apparent, primarily that T{sub max} of each bromide hydrate is less than for the corresponding chloride, and that for a given halide nD{sub 2}O (n=1 or 2) deuterates exhibit lesser T{sub max} than do nH{sub 2}O hydrates. A monoclinic unit cell determined from powder X-ray diffraction data on NiBr{sub 2}·2D{sub 2}O is different from and slightly larger than that of NiBr{sub 2}·2H{sub 2}O. This provides some rationale for the difference in magnetic properties between these. - Highlights: • The magnetism of Ni(II) chloride and bromide dihydrates and monohydrates is studied. • Effects of replacing H{sub 2}O by D{sub 2}O are examined for both hydration states and both halides. • Exchange interactions in bromides are weaker than in corresponding chlorides. • Exchange interactions are weaker in D{sub 2}O than in corresponding H{sub 2}O containing systems. • The unit cell of NiBr{sub 2}·2D{sub 2}O is different from and slightly larger than that of NiBr{sub 2}·2H{sub 2}O.

  17. Understanding the Slow Transient Optoelectronic Response of Hybrid Organic-Inorganic Halide Perovskites

    Science.gov (United States)

    Jacobs, Daniel Louis

    Hybrid organic-inorganic halide perovskites, particularly methylammonium lead triiodide (MAPbI3), have emerged within the past decade as an exciting class of photovoltaic materials. In less than ten years, MAPbI3-based photovoltaic devices have seen unprecedented performance growth, with photoconversion efficiency increasing from 3% to over 22%, making it competitive with traditional high-efficiency solar cells. Furthermore, the fabrication of MAPbI3 devices utilize low-temperature solution processing, which could facilitate ultra low cost manufacturing. However, MAPbI3 suffers from significant instabilities under working conditions that have limited their applications outside of the laboratory. The instability of the MAPbI3 material can be generalized as a complex, slow transient optoelectronic response (STOR). The mechanism of the generalized STOR is dependent on the native defects of MAPbI3, but detailed understanding of the material defect properties is complicated by the complex ionic bonding of MAPbI3. Furthermore, characterization of the intrinsic material's response is complicated by the diverse approach to material processing and device architecture across laboratories around the world. In order to understand and mitigate the significant problems of MAPbI3 devices, a new approach focused on the material response, rather than the full device response, must be pursued. This dissertation highlights the work to analyze and mitigate the STOR intrinsic to MAPbI3. An experimental platform was developed based on lateral interdigitated electrode (IDE) arrays capable of monitoring the current and photoluminescence response simultaneously. By correlating the dynamics of the current and photoluminescence (PL) responses, both charge trapping and ion migration mechanisms were identified to contribute to the STOR. Next, a novel fabrication technique is introduced that is capable of reliably depositing MAPbI3 thin films with grain sizes at least an order of magnitude

  18. An experimental investigation of untriggered film boiling collapse

    International Nuclear Information System (INIS)

    Naylor, P.

    1985-03-01

    Film boiling has been investigated in a stagnant pool, using polished brass or anodised aluminium alloy rods in water. Experimental boiling curves were obtained, and pronounced ripples on the vapour/liquid interface were photographed. A criterion for untriggered film boiling collapse is proposed, consistent with experimental results. Application of the results to molten fuel coolant interaction studies is discussed. (U.K.)

  19. Film Reviews.

    Science.gov (United States)

    Lance, Larry M.; Atwater, Lynn

    1987-01-01

    Reviews four Human Sexuality films and videos. These are: "Personal Decisions" (Planned Parenthood Federation of America, 1985); "The Touch Film" (Sterling Production, 1986); "Rethinking Rape" (Film Distribution Center, 1985); "Not A Love Story" (National Film Board of Canada, 1981). (AEM)

  20. Photographic program of a BWR for ALARA

    International Nuclear Information System (INIS)

    Dodd, A.M.; Parry, J.O.

    1984-01-01

    High radiation areas have often been photographed in commercial nuclear plants to identify radiation sources and equipment so workers having to go into the areas become familiar with them prior to entering. This helps minimize the workers' time in a high radiation area and is useful as a visual aid in training. Previous problems encountered in using this type of file included indexing, storing for long term use and reproducing photos for use in the field. At WNP-2, a program has been adopted from Aerojet of Idaho where negatives from photographs are mounted on computer aperture cards. The cards are coded to identify the equipment, physical location in the plant, reference drawings and other data. The aperture cards are reproduced using a process called Diazo. The information is put in a data file that can be sorted by any field on the card. A paper copy of the photo can be made in seconds on a machine similar to a dry silver copier, then mounted for training or maintenance purposes. The cost of duplicating the aperture cards and/or the paper copies is a fraction of that for reproducing color glossies. The computer data file provides cross-referencing to correlate the equipment with the photograph. The results are low cost, easy storage and easy access to the photograph file. Using this program, several thousand photographs can easily be stored and used

  1. Silver nanoparticles from silver halide photography to plasmonics

    CERN Document Server

    Tani, Tadaaki

    2015-01-01

    This book provides systematic knowledge and ideas on nanoparticles of Ag and related materials. While Ag and metal nanoparticles are essential for plasmonics, silver halide (AgX) photography relies to a great extent on nanoparticles of Ag and AgX which have the same crystal structure and have been studied extensively for many years. This book has been written to combine the knowledge of nanoparticles of Ag and related materials in plasmonics and AgX photography in order to provide new ideas for metal nanoparticles in plasmonics. Chapters 1–3 of this book describe the structure and formation of nanoparticles of Ag and related materials. Systematic descriptions of the structure and preparation of Ag, Au, and noble-metal nanoparticles for plasmonics are followed by and related to those of nanoparticles of Ag and AgX in AgX photography. Knowledge of the structure and preparation of Ag and AgX nanoparticles in photography covers nanoparticles with widely varying sizes, shapes, and structures, and formation proce...

  2. Modelling current transfer to cathodes in metal halide plasmas

    International Nuclear Information System (INIS)

    Benilov, M S; Cunha, M D; Naidis, G V

    2005-01-01

    This work is concerned with investigation of the main features of current transfer to cathodes under conditions characteristic of metal halide (MH) lamps. It is found that the presence of MHs in the gas phase results in a small decrease of the cathode surface temperature and of the near-cathode voltage drop in the diffuse mode of current transfer; the range of stability of the diffuse mode expands. Effects caused by a variation of the work function of the cathode surface owing to formation of a monolayer of alkali metal atoms on the surface are studied for particular cases where the monolayer is composed of sodium or caesium. It is found that the formation of the sodium monolayer affects the diffuse mode of current transfer only moderately and in the same direction that the presence of metal atoms in the gas phase affects it. Formation of the caesium monolayer produces a dramatic effect: the cathode surface temperature decreases very strongly, the diffuse-mode current-voltage characteristic becomes N-S-shaped

  3. A new fundamental hydrogen defect in alkali halides

    International Nuclear Information System (INIS)

    Morato, S.P.; Luety, F.

    1978-01-01

    Atom hydrogen in neutral (H 0 ) and negative (H - ) form on substitutional and interstitial lattice sites gives rise to well characterized model defects in alkali-halides (U,U 1 ,U 2 ,U 3 centers), which have been extensively investigated in the past. When studying the photo-decomposition of OH - defects, a new configuration of atomic charged hidrogen was discovered, which can be produced in large quantities in the crystal and is apparently not connected to any other impurity. This new hidrogen defect does not show any pronounced electronic absorption, but displays a single sharp local mode band (at 1114cm -1 in KCl) with a perfect isotope shift. The defect can be produced by various UV or X-ray techniques in crystais doped with OH - , Sh - or H - defects. A detailed study of its formation kinetics at low temperature shows that it is primarily formed by the reaction of a mobile CI 2 - crowdion (H-center) with hidrogen defects [pt

  4. Isotope effects in aqueous solvation of simple halides

    Science.gov (United States)

    Videla, Pablo E.; Rossky, Peter J.; Laria, D.

    2018-03-01

    We present a path-integral-molecular-dynamics study of the thermodynamic stabilities of DOH⋯ X- and HOD⋯ X- (X = F, Cl, Br, I) coordination in aqueous solutions at ambient conditions. In agreement with experimental evidence, our results for the F- case reveal a clear stabilization of the latter motif, whereas, in the rest of the halogen series, the former articulation prevails. The DOH⋯ X- preference becomes more marked the larger the size of the ionic solute. A physical interpretation of these tendencies is provided in terms of an analysis of the global quantum kinetic energies of the light atoms and their geometrical decomposition. The stabilization of the alternative ionic coordination geometries is the result of a delicate balance arising from quantum spatial dispersions along parallel and perpendicular directions with respect to the relevant O-H⋯X- axis, as the strength of the water-halide H-bond varies. This interpretation is corroborated by a complementary analysis performed on the different spectroscopic signals of the corresponding IR spectra.

  5. Cerium doped lanthanum halides: fast scintillators for medical imaging

    International Nuclear Information System (INIS)

    Selles, O.

    2006-12-01

    This work is dedicated to two recently discovered scintillating crystals: cerium doped lanthanum halides (LaCl 3 :Ce 3+ and LaBr 3 :Ce 3+ ).These scintillators exhibit interesting properties for gamma detection, more particularly in the field of medical imaging: a short decay time, a high light yield and an excellent energy resolution. The strong hygroscopicity of these materials requires adapting the usual experimental methods for determining physico-chemical properties. Once determined, these can be used for the development of the industrial manufacturing process of the crystals. A proper comprehension of the scintillation mechanism and of the effect of defects within the material lead to new possible ways for optimizing the scintillator performance. Therefore, different techniques are used (EPR, radioluminescence, laser excitation, thermally stimulated luminescence). Alongside Ce 3+ ions, self-trapped excitons are involved in the scintillation mechanism. Their nature and their role are detailed. The knowledge of the different processes involved in the scintillation mechanism leads to the prediction of the effect of temperature and doping level on the performance of the scintillator. A mechanism is proposed to explain the thermally stimulated luminescence processes that cause slow components in the light emission and a loss of light yield. Eventually the study of afterglow reveals a charge transfer to deep traps involved in the high temperature thermally stimulated luminescence. (author)

  6. Transmission electron microscopy of weakly deformed alkali halide crystals

    International Nuclear Information System (INIS)

    Strunk, H.

    1976-01-01

    Transmission electron microscopy (TEM) is applied to the investigation of the dislocation arrangement of [001]-orientated alkali halide crystals (orientation four quadruple slip) deformed into stage I of the work-hardenig curve. The investigations pertain mainly to NaCl - (0.1-1) mole-% NaBr crystals, because these exhibit a relatively long stage I. The time available for observing the specimens is limited by the ionization radiation damage occuring in the microscope. An optimum reduction of the damage rate is achieved by a combination of several experimental techniques that are briefly outlined. The crystals deform essentially in single glide. According to the observations, stage I deformation of pure and weakly alloyed NaCl crystals is characterized by the glide of screw dislocations, which bow out between jogs and drag dislocation dipoles behind them. In crystals with >= 0.5 mole-% NaBr this process is not observed to occur. This is attributed to the increased importance of solid solution hardening. (orig.) [de

  7. Strong Carrier–Phonon Coupling in Lead Halide Perovskite Nanocrystals

    Science.gov (United States)

    2017-01-01

    We highlight the importance of carrier–phonon coupling in inorganic lead halide perovskite nanocrystals. The low-temperature photoluminescence (PL) spectrum of CsPbBr3 has been investigated under a nonresonant and a nonstandard, quasi-resonant excitation scheme, and phonon replicas of the main PL band have been identified as due to the Fröhlich interaction. The energy of longitudinal optical (LO) phonons has been determined from the separation of the zero phonon band and phonon replicas. We reason that the observed LO phonon coupling can only be related to an orthorhombically distorted crystal structure of the perovskite nanocrystals. Additionally, the strength of carrier–phonon coupling has been characterized using the ratio between the intensities of the first phonon replica and the zero-phonon band. PL emission from localized versus delocalized carriers has been identified as the source of the observed discrepancies between the LO phonon energy and phonon coupling strength under quasi-resonant and nonresonant excitation conditions, respectively. PMID:29019652

  8. Thermodynamic origin of instability in hybrid halide perovskites

    Science.gov (United States)

    Tenuta, E.; Zheng, C.; Rubel, O.

    2016-11-01

    Degradation of hybrid halide perovskites under the influence of environmental factors impairs future prospects of using these materials as absorbers in solar cells. First principle calculations can be used as a guideline in search of new materials, provided we can rely on their predictive capabilities. We show that the instability of perovskites can be captured using ab initio total energy calculations for reactants and products augmented with additional thermodynamic data to account for finite temperature effects. Calculations suggest that the instability of CH3NH3PbI3 in moist environment is linked to the aqueous solubility of the CH3NH3I salt, thus making other perovskite materials with soluble decomposition products prone to degradation. Properties of NH3OHPbI3, NH3NH2PbI3, PH4PbI3, SbH4PbI3, CsPbBr3, and a new hypothetical SF3PbI3 perovskite are studied in the search for alternative solar cell absorber materials with enhanced chemical stability.

  9. Quantification of Ionic Diffusion in Lead Halide Perovskite Single Crystals

    KAUST Repository

    Peng, Wei

    2018-05-25

    Lead halide perovskites are mixed electronic/ionic semiconductors that have recently revolutionized the photovoltaics field. The physical characterization of the ionic conductivity has been rather elusive due to the highly intermixing of ionic and electronic current. In this work the synthesis of low defect density monocrystalline MAPbBr3 (MA=Methyl ammonium) solar cells free of hole transport layer (HTL) suppresses the effect of electronic current. Impedance spectroscopy reveals the characteristic signature of ionic diffusion (the Warburg element and transmission line equivalent circuit) and ion accumulation at the MAPbBr3/Au interface. Diffusion coefficients are calculated based on a good correlation between thickness of MAPbBr3 and characteristic diffusion transition frequency. In addition, reactive external interfaces are studied by comparison of polycrystalline MAPbBr3 devices prepared either with or without a HTL. The low frequency response in IS measurements is correlated with the chemical reactivity of moving ions with the external interfaces and diffusion into the HTL.

  10. Post-synthetic halide conversion and selective halogen capture in hybrid perovskites† †Electronic supplementary information (ESI) available. CCDC 1048945–1048947. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c5sc01135c

    Science.gov (United States)

    Solis-Ibarra, D.; Smith, I. C.

    2015-01-01

    Reaction with halogen vapor allows us to post-synthetically exchange halides in both three- (3D) and two-dimensional (2D) organic–inorganic metal-halide perovskites. Films of 3D Pb–I perovskites cleanly convert to films of Pb–Br or Pb–Cl perovskites upon exposure to Br2 or Cl2 gas, respectively. This gas–solid reaction provides a simple method to produce the high-quality Pb–Br or Pb–Cl perovskite films required for optoelectronic applications. Reactivity with halogens can be extended to the organic layers in 2D metal-halide perovskites. Here, terminal alkene groups placed between the inorganic layers can capture Br2 gas through chemisorption to form dibromoalkanes. This reaction's selectivity for Br2 over I2 allows us to scrub Br2 to obtain high-purity I2 gas streams. We also observe unusual halogen transfer between the inorganic and organic layers within a single perovskite structure. Remarkably, the perovskite's crystallinity is retained during these massive structural rearrangements. PMID:29218171

  11. Nobels Nobels laureates photographed by Peter Badge

    CERN Document Server

    2008-01-01

    A unique photographic record of all living Nobel laureates. In this handsome coffee-table book, photographer Peter Badge captures the likeness of every living Nobel laureate in a lasting black-and-white image -- more than 300 striking portraits in all. Brief biographical sketches accompanying the large-scale photographs pay homage to each laureate's singular contribution to science, literature or world peace. Bringing readers face-to-face with Nelson Mandela, Jimmy Carter, the Dalai Lama, James Watson, Gabriel García Márquez, Toni Morrison, Rita Levi-Montalcini, Linda Buck, and Paul Samuelson among many others, NOBELS offers an intimate and compelling look at well-known honorees as well as lesser-known recipients. A fascinating word/image tableau.

  12. Materials Processing Routes to Trap-Free Halide Perovskites

    KAUST Repository

    Buin, Andrei; Pietsch, Patrick; Xu, Jixian; Voznyy, Oleksandr; Ip, Alexander H.; Comin, Riccardo; Sargent, Edward H.

    2014-01-01

    that the specific choice of growth conditions and chemical precursors is central to achieving superior performance from these materials; yet the roles and mechanisms underlying the selection of materials processing route is poorly understood. Here we show that films

  13. Chemical Processing effects on the radiation doses measured by Film Dosimeter System

    International Nuclear Information System (INIS)

    Mihai, F.

    2009-01-01

    Halide film dosimetry is a quantitative method of measurement of the radiation doses. The fog density and chemical processing of the dosimeter film affect the radiation dose measurement accuracy. This work presents the effect of the developer solution concentration on the response of the dosimetric film which different fog densities. Thus, three batches of film, dosimeters with following fog density 0.312 ± 1.31 %, 0.71 ± 0.59% and 0.77 ± 0.81 %, were irradiated to 137 Cs standard source to dose value of 1mSv. The halide films have been chemical processed at different concentrations of the developer solution: 20 %; 14.29 %; 11.11%; all other physics-chemical conditions in baths of development have been kept constants. Concentration of 20% is considered to be chemical processed standard conditions of the films. In case of the films exposed to 1 mSv dose, optical density recorded on the low fog films processed at 20% developer solution is rather closed of high fog film optical densities processed at 11.11% developer solution concentration. Also, the chemical processing effect on the image contrast was taken into consideration

  14. Comparative study of thermoluminescent, radiophotoluminescent and photographic dosemeters

    International Nuclear Information System (INIS)

    Deus, S.F.

    1976-01-01

    Comparison was made between the response of three differents dosimetric systems, namely, photographic, thermoluminescent (TL) and radiophotoluminescent (RPL). The comparison was divided in two parts. The first was carried out in known radiation conditions (exposure, normal incidence, energy) and under controlled environment (approximately 27 0 C temperature, approximately 70% relative humidity). Under these conditions, the response as a function of exposure and energy, the relation of the linearity to the energy, the lowest detectable exposure, and the reproducibility, were studied. The response against esposure at 37 KeVef and at 1 MeV was found to be linear in the region of interest to routine personnel dosimetry for all dosimeters except for the filmes. In the second part, the relative response of the dosimeters was verified under the uncontrolled conditions of personnel dosimetry. As the CaSO 4 :Dy is the most sensitive dosimeter, comparison was made using this dosimeter as the standard, in which case one finds that 20 of 29 TLD-100 dosimeters give the same reading within 30%, 13 of 29 RPL dosimeters agree within 30%, and only 3 of 29 films fall within 30% [pt

  15. The impact of alkali metal halide electron donor complexes in the photocatalytic degradation of pentachlorophenol

    Energy Technology Data Exchange (ETDEWEB)

    Khuzwayo, Z., E-mail: zack.khuzwayo@up.ac.za; Chirwa, E.M.N

    2017-01-05

    Highlights: • Facilitation of photocatalysis using simple metal-halides as VB hole scavengers. • Recombination prevention by coupled valence and conduction band approaches. • Determination of anions critical levels beyond which process retardation occurs. • Determination of the photocatalytic process rate of reaction kinetics. - Abstract: The performance of photocatalytic oxidation of chemical pollutants is subjected to the presence of anion complexes in natural waters. This study investigated the influence of alkali metal (Na{sup +} (sodium), K{sup +} (potassium)) halides (Cl{sup −} (chloride), Br{sup −} (bromide), F{sup −} (fluoride)) as inorganic ion sources in the photocatalytic degradation of pentachlorophenol (PCP) in batch systems. It was found that the exclusive presence of halides in the absence of an electron acceptor adequately facilitated the photocatalyst process below critical levels of anion populations, where beyond the critical point the process was significantly hindered. Below the determined critical point, the performance in some cases near matches that of the facilitation of the photocatalytic process by exclusive oxygen, acting as an electron scavenger. The coupling of halide ions and oxygenation presented significantly improved photo-oxidation of PCP, this was confirmed by the inclusion of formic acid as a comparative electron donor. The Langmuir-Hinshelwood kinetic expression was used to calculate the performance rate kinetics. The probable impact of the halide anions was discussed with regards to the process of electron hole pair recombination prevention.

  16. Cloud chamber photographs of the cosmic radiation

    CERN Document Server

    Rochester, George Dixon

    1952-01-01

    Cloud Chamber Photographs of the Cosmic Radiation focuses on cloud chamber and photographic emulsion wherein the tracks of individual subatomic particles of high energy are studied. The publication first offers information on the technical features of operation and electrons and cascade showers. Discussions focus on the relationship in time and space of counter-controlled tracks; techniques of internal control of the cloud chamber; cascade processes with artificially-produced electrons and photons; and nuclear interaction associated with an extensive shower. The manuscript then elaborates on

  17. Development of Curriculum of Learning through Photograph

    Science.gov (United States)

    Suzuki, Keiko; Aoki, Naokazu; Kobayashi, Hiroyuki

    A curriculum of an integrated learning using power of photography in the junior highschool was constructed, and was experimented in the class "Seminar for Photographic Expression" of the integrated learning at a junior high school. The center of the curriculum is viewing photographs and self-expression using photography. By comparing the results of questionnaires investigation between before and after the class it is suggested that the curriculum brings about increase in self-esteem, empathy, and motivation for learning. This educational effect is really to foster ability to live self-sufficient lives. On the basis of these results curriculums which can be conducted by anyone at every junior highschool were proposed.

  18. Organisation of a laboratory of photographic dosimetry

    International Nuclear Information System (INIS)

    Soudain, Georges

    1961-01-01

    After a recall of the main properties of photographic dosimetry, the author describes the principle of this method, and comments the issue of chromatic sensitivity of photographic emulsions. He discusses the calibration process for gamma radiation, X rays, and thermal neutrons. He describes how fast neutron dosimetry is performed. In the next part, he describes the organisation of the photometry laboratory which has to prepare and distribute dosimeters, to collect and exploit them, and to prepare a publication of results. These different missions and tasks are described

  19. PREFACE: Workshop Photograph and Program

    Science.gov (United States)

    2011-07-01

    Workshop photograph Workshop Program Sunday 28 March 201019:00-21:00 Reception at Okura Frontier Hotel Tsukuba(Buffet style dinner with drink) Monday 29 March 2010Introduction (Chair: André Rubbia (ETH Zurich))09:00 Welcome address (05') Atsuto Suzuki (KEK)09:05 Message from CERN on neutrino physics (10') Sergio Bertolucci (CERN)09:15 Message from FNAL on neutrino physics (10') Young Kee Kim (FNAL)09:25 Message from KEK on neutrino physics (10') Koichiro Nishikawa (KEK)09:35 Introductory remark on GLA2010 (10') Takuya Hasegawa (KEK) Special session (Chair: Koichiro Nishikawa (KEK))09:45 The ICARUS Liquid Argon TPC (45') Carlo Rubbia (CERN)10:30-11:00 Coffee break Main goals of Giant Liquid Argon Charge Imaging Experiments I (Chair: Takashi Kobayashi (KEK))11:00 Results from massive underground detectors (non accelerator) (30') Takaaki Kajita (ICRR, U. of Tokyo)11:30 Present long baseline neutrino experiments (30') Chang Kee Jung (SUNY Stony Brook)12:00-12:10 Workshop picture12:10-14:00 Lunch break Main goals of Giant Liquid Argon Charge Imaging Experiments II (Chair: Takashi Kobayashi (KEK))14:00 Physics goals of the next generation massive underground experiments (30') David Wark (Imperial College London)14:30 Near detectors for long baseline neutrino experiments (20') Tsuyoshi Nakaya (Kyoto U.) Lessons on Liquid Argon Charge Imaging technology from ongoing developments (Chair: Chang Kee Jung (SUNY Stony Brook))14:50 WARP (30') Claudio Montanari (U. of Pavia)15:20 ArDM (30') Alberto Marchionni (ETH Zurich)15:50 From ArgoNeuT to MicroBooNE (30') Bonnie Fleming (Yale U.)16:20 250L (30') Takasumi Maruyama (KEK)16:50 The DEAP/CLEAN project (20') Mark Boulay (Queen's U.)17:10-17:40 Coffee break Lessons from Xe based Liquids Imaging detectors (Chair: Flavio Cavanna (U. of L'Aquilla))17:30 MEG (20') Satoshi Mihara (KEK)17:50 The XENON project (20') Elena Aprile (Columbia U.)18:10 XMASS (20') Hiroyuki Sekiya (ICRR, U. of Tokyo) Studies on physics performance (Chair

  20. Iron halide mediated atom transfer radical polymerization of methyl methacrylate with N-Alkyl-2-pyridylmethanimine as the ligand

    NARCIS (Netherlands)

    Zhang, H.; Schubert, U.S.

    2004-01-01

    The controlled atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) catalyzed by iron halide/N-(n-hexyl)-2-pyridylmethanimine (NHPMI) is described. The ethyl 2-bromoisobutyrate (EBIB)-initiated ATRP with [MMA]0/[EBIB]0/[iron halide]0/[NHPMI]0 = 150/1/1/2 was better controlled in

  1. Homocoupling of aryl halides in flow: Space integration of lithiation and FeCl3 promoted homocoupling

    Directory of Open Access Journals (Sweden)

    Aiichiro Nagaki

    2011-08-01

    Full Text Available The use of FeCl3 resulted in a fast homocoupling of aryllithiums, and this enabled its integration with the halogen–lithium exchange reaction of aryl halides in a flow microreactor. This system allows the homocoupling of two aryl halides bearing electrophilic functional groups, such as CN and NO2, in under a minute.

  2. A study on the electrochemical behaviour of polypyrrole films in concentrated aqueous alkali halide electrolytes

    DEFF Research Database (Denmark)

    Jafeen, M. J. M.; Careem, M.A.; Skaarup, Steen

    2014-01-01

    transport in concentrated electrolytes is found to be very low. In dilute electrolytes, water molecules accompany counter ions as solvated molecules and due to osmotic effect. In concentrated electrolytes, water movement is less due to limited availability of free water as well as a smaller osmotic pressure...

  3. On the reverse. Some notes on photographic images from the Warburg Institute Photographic Collection

    Directory of Open Access Journals (Sweden)

    Katia Mazzucco

    2012-10-01

    Full Text Available How can the visual and textual data about an image – the image of a work of art – on recto and verso of a picture be interpreted? An analogical-art-documentary photograph represents a palimpsest to be considered layer by layer. The examples discussed in this article, which refer to both Aby Warburg himself and the first nucleus of the Warburg Institute Photographic Collection, contribute to effectively outline elements of the debate around the question of the photographic reproduction of the work of art as well as of the position of photography in relation to the perception of the work of art.

  4. The role of halide ions on the electrochemical behaviour of iron in alkali solutions

    Science.gov (United States)

    Begum, S. Nathira; Muralidharan, V. S.; Basha, C. Ahmed

    2008-02-01

    Active dissolution and passivation of transition metals in alkali solutions is of technological importance in batteries. The performance of alkaline batteries is decided by the presence of halides as they influence passivation. Cyclic voltammetric studies were carried out on iron in different sodium hydroxide solutions in presence of halides. In alkali solutions iron formed hydroxo complexes and their polymers in the interfacial diffusion layer. With progress of time they formed a cation selective layer. The diffusion layer turned into bipolar ion selective layer consisted of halides, a selective inner sublayer to the metal side and cation selective outer layer to the solution side. At very high anodic potentials, dehydration and deprotonation led to the conversion of salt layer into an oxide.

  5. Holographic Optical Elements Recorded in Silver Halide Sensitized Gelatin Emulsions. Part I. Transmission Holographic Optical Elements

    Science.gov (United States)

    Kim, Jong Man; Choi, Byung So; Kim, Sun Il; Kim, Jong Min; Bjelkhagen, Hans I.; Phillips, Nicholas J.

    2001-02-01

    Silver halide sensitized gelatin (SHSG) holograms are similar to holograms recorded in dichromated gelatin (DCG), the main recording material for holographic optical elements (HOE s). The drawback of DCG is its low sensitivity and limited spectral response. Silver halide materials can be processed in such a way that the final hologram will have properties like a DCG hologram. Recently this technique has become more interesting since the introduction of new ultra-high-resolution silver halide emulsions. An optimized processing technique for transmission HOE s recorded in these materials is introduced. Diffraction efficiencies over 90% can be obtained for transmissive diffraction gratings. Understanding the importance of the selective hardening process has made it possible to obtain results similar to conventional DCG processing. The main advantage of the SHSG process is that high-sensitivity recording can be performed with laser wavelengths anywhere within the visible spectrum. This simplifies the manufacturing of high-quality, large-format HOE s.

  6. Purcell effect in an organic-inorganic halide perovskite semiconductor microcavity system

    International Nuclear Information System (INIS)

    Wang, Jun; Wang, Yafeng; Hu, Tao; Wu, Lin; Shen, Xuechu; Chen, Zhanghai; Cao, Runan; Xu, Fei; Da, Peimei; Zheng, Gengfeng; Lu, Jian

    2016-01-01

    Organic-inorganic halide perovskite semiconductors with the attractive physics properties, including strong photoluminescence (PL), huge oscillator strengths, and low nonradiative recombination losses, are ideal candidates for studying the light-matter interaction in nanostructures. Here, we demonstrate the coupling of the exciton state and the cavity mode in the lead halide perovskite microcavity system at room temperature. The Purcell effect in the coupling system is clearly observed by using angle-resolved photoluminescence spectra. Kinetic analysis based on time-resolved PL reveals that the spontaneous emission rate of the halide perovskite semiconductor is significantly enhanced at resonance of the exciton energy and the cavity mode. Our results provide the way for developing electrically driven organic polariton lasers, optical devices, and on-chip coherent quantum light sources

  7. Ionic conductivity of N-alkyl pyridinium halides mesophases

    International Nuclear Information System (INIS)

    Meftah, Ahmed

    1980-01-01

    The quasi anhydrous N-alkyl pyridinium halides undergo at a temperature T c a phase transition from a crystalline isolating state to a conducting mesophase (σ = 3.10 -2 Ω -1 cm -1 ). The transition temperature depends on the nature on counter-ion and on the aliphatic chain length. The present study is devoted to the N-alkyl pyridinium chlorides, bromides and iodides varying the number of carbon atoms in the chain from ten to twenty two. The transition temperatures T c were found to increase from 30 deg. C up to 110 deg. C by a step of 10 deg. C for two added carbon atoms in the chain. The electrical measurements have shown that the conductivity of the mesophases which is ionic in origin is due to a large mobility of counter-ions in hydrophilic parts. At high frequencies (F > 10 3 Hz) ionic conductivity predominates in the bulk and does not depend on frequency. At low frequencies (F 3 Hz) the most important are interface phenomena depending on the square root of inverse frequency (ω -1/2 ) and being due to an electronic exchange limited by diffusion velocity of counter-ions. The electrical conductivity depends weekly on the chain length and the mesophases textures. The most conducting mesophase is the optically isotropic. The conductivity increases with increasing water content of the system and decreases with increasing atomic number of counter-ion. The diffusion measurements by radioactive tracers confirm the ionic character of charge carriers although the diffusion factors obtained by this method are largely higher than the calculated ones from the conductivity values. (author) [fr

  8. Molecular beam scattering from clean surfaces of alkali halides

    International Nuclear Information System (INIS)

    Meyers, J.A.

    1975-01-01

    Molecular beam scattering of light gases from in situ cleaved alkali halide surfaces has been studied as a means of developing molecular beam scattering as a surface characterization tool and as a means of obtaining information about the gas atom-solid surface potential interaction. For 4 He scattering from LiF carried out under improved resolution the main results are: (1) there are four bound states in the surface potential well, as energies of -5.8, -2.2, -0.6 and -0.1 MeV. (2) Most of the structure designated as ''fine structure'' is due either to transitions to these four levels via various small reciprocal lattice vectors or to the opening of diffraction channels. (3) The transitions involving the (01) and (0 anti 1) reciprocal lattice vectors (i.e., the ones nearly perpendicular to the incident wavevector) are strong; as much as 85 percent of the specular intensity may be removed. Transitions via the other small reciprocal lattice vectors are much weaker. (4) The widths of the lines are consistent with the velocity distribution, which has a half-width of about 2 percent. (5) The observed energies agree fairly well with those calculated for a zeta-function potential, but are not consistent with a Morse potential. The preliminary results for 4 He/NaF scattering are that there are three bound-states in the surface potential well and are quite similar to the LiF results. These energies are -5.0, -1.9, and -0.5 MeV. 4 He/NaF selective adsorption also shows ''fine structure'' and a more detailed analysis is called for here

  9. Origins and mechanisms of hysteresis in organometal halide perovskites

    Science.gov (United States)

    Li, Cheng; Guerrero, Antonio; Zhong, Yu; Huettner, Sven

    2017-05-01

    Inorganic-organic halide organometal perovskites, such as CH3NH3PbI3 and CsPbI3, etc, have been an unprecedented rising star in the field of photovoltaics since 2009, owing to their exceptionally high power conversion efficiency and simple fabrication processability. Despite its relatively short history of development, intensive investigations have been concentrating on this material; these have ranged from crystal structure analysis and photophysical characterization to performance optimization and device integration, etc. Yet, when applied in photovoltaic devices, this material suffers from hysteresis, that is, the difference of the current-voltage (I-V) curve during sweeping in two directions (from short-circuit towards open-circuit and vice versa). This behavior may significantly impede its large-scale commercial application. This Review will focus on the recent theoretical and experimental efforts to reveal the origin and mechanism of hysteresis. The proposed origins include (1) ferroelectric polarization, (2) charge trapping/detrapping, and (3) ion migration. Among them, recent evidence consistently supports the idea that ion migration plays a key role for the hysteretic behavior in perovskite solar cells (PSCs). Hence, this Review will summarize the recent results on ion migration such as the migrating ion species, activation energy measurement, capacitive characterization, and internal electrical field modulation, etc. In addition, this Review will also present the devices with alleviation/elimination of hysteresis by incorporating either large-size grains or phenyl-C61-butyric acid methyl ester molecules. In a different application, the hysteretic property has been utilized in photovoltaic and memristive switching devices. In sum, by examining these three possible mechanisms, it is concluded that the origin of hysteresis in PSCs is associated with a combination of effects, but mainly limited by ion/defect migration. This strong interaction between ion

  10. Bright triplet excitons in caesium lead halide perovskites

    Science.gov (United States)

    Becker, Michael A.; Vaxenburg, Roman; Nedelcu, Georgian; Sercel, Peter C.; Shabaev, Andrew; Mehl, Michael J.; Michopoulos, John G.; Lambrakos, Samuel G.; Bernstein, Noam; Lyons, John L.; Stöferle, Thilo; Mahrt, Rainer F.; Kovalenko, Maksym V.; Norris, David J.; Rainò, Gabriele; Efros, Alexander L.

    2018-01-01

    Nanostructured semiconductors emit light from electronic states known as excitons. For organic materials, Hund’s rules state that the lowest-energy exciton is a poorly emitting triplet state. For inorganic semiconductors, similar rules predict an analogue of this triplet state known as the ‘dark exciton’. Because dark excitons release photons slowly, hindering emission from inorganic nanostructures, materials that disobey these rules have been sought. However, despite considerable experimental and theoretical efforts, no inorganic semiconductors have been identified in which the lowest exciton is bright. Here we show that the lowest exciton in caesium lead halide perovskites (CsPbX3, with X = Cl, Br or I) involves a highly emissive triplet state. We first use an effective-mass model and group theory to demonstrate the possibility of such a state existing, which can occur when the strong spin-orbit coupling in the conduction band of a perovskite is combined with the Rashba effect. We then apply our model to CsPbX3 nanocrystals, and measure size- and composition-dependent fluorescence at the single-nanocrystal level. The bright triplet character of the lowest exciton explains the anomalous photon-emission rates of these materials, which emit about 20 and 1,000 times faster than any other semiconductor nanocrystal at room and cryogenic temperatures, respectively. The existence of this bright triplet exciton is further confirmed by analysis of the fine structure in low-temperature fluorescence spectra. For semiconductor nanocrystals, which are already used in lighting, lasers and displays, these excitons could lead to materials with brighter emission. More generally, our results provide criteria for identifying other semiconductors that exhibit bright excitons, with potential implications for optoelectronic devices.

  11. Cryptography Would Reveal Alterations In Photographs

    Science.gov (United States)

    Friedman, Gary L.

    1995-01-01

    Public-key decryption method proposed to guarantee authenticity of photographic images represented in form of digital files. In method, digital camera generates original data from image in standard public format; also produces coded signature to verify standard-format image data. Scheme also helps protect against other forms of lying, such as attaching false captions.

  12. The Social Effects of War Photographs

    Directory of Open Access Journals (Sweden)

    Gökhan DEMİREL

    2017-07-01

    Full Text Available In today’s world, knowledge is increasingly impacted via visual representation. The messages sent through various sources, such as newspaper, television and the internet, lead people to form opinions about various topics. In this context, photography is one of the most powerful source of information. Moreover, the visual power and the ability to show nonverbal communication makes it a perfect tool for propaganda. These days, photographs showing war themes are used more often than the past. It can be said that war photographs serve as a tool for showing the world the realities of war to those, even to those who turn their back to massacres. After all, a dead body creates a shocking effect in the seer. In this study, the context of the photographs of the war, examined in sample of photograph of Aylan Kurdi, which became the “icon” of immigration due to Syrian civil war and war it relates to and it is studied to understand how it is assessed and understood considering the environment and conditions on the date the photo was taken, existing values, beliefs and things happened in the world in that time, from a critical point of view.

  13. Nanostructure of propylammonium nitrate in the presence of poly(ethylene oxide) and halide salts

    Science.gov (United States)

    Stefanovic, Ryan; Webber, Grant B.; Page, Alister J.

    2018-05-01

    Nanoscale structure of protic ionic liquids is critical to their utility as molecular electrochemical solvents since it determines the capacity to dissolve salts and polymers such as poly(ethylene oxide) (PEO). Here we use quantum chemical molecular dynamics simulations to investigate the impact of dissolved halide anions on the nanostructure of an archetypal nanostructured protic ionic liquid, propylammonium nitrate (PAN), and how this impacts the solvation of a model PEO polymer. At the molecular level, PAN is nanostructured, consisting of charged/polar and uncharged/nonpolar domains. The charged domain consists of the cation/anion charge groups, and is formed by their electrostatic interaction. This domain solvophobically excludes the propyl chains on the cation, which form a distinct, self-assembled nonpolar domain within the liquid. Our simulations demonstrate that the addition of Cl- and Br- anions to PAN disrupts the structure within the PAN charged domain due to competition between nitrate and halide anions for the ammonium charge centre. This disruption increases with halide concentration (up to 10 mol. %). However, at these concentrations, halide addition has little effect on the structure of the PAN nonpolar domain. Addition of PEO to pure PAN also disrupts the structure within the charged domain of the liquid due to hydrogen bonding between the charge groups and the terminal PEO hydroxyl groups. There is little other association between the PEO structure and the surrounding ionic liquid solvent, with strong PEO self-interaction yielding a compact, coiled polymer morphology. Halide addition results in greater association between the ionic liquid charge centres and the ethylene oxide components of the PEO structure, resulting in reduced conformational flexibility, compared to that observed in pure PAN. Similarly, PEO self-interactions increase in the presence of Cl- and Br- anions, compared to PAN, indicating that the addition of halide salts to PAN

  14. Structures of butyl ions formed by electron impact ionization of isomeric butyl halides and alkanes

    International Nuclear Information System (INIS)

    Shold, D.M.; Ausloos, P.

    1978-01-01

    Using a pulsed ion cyclotron resonance (ICR) spectrometer, it is demonstrated that at pressures of about 10 -6 Torr and at observation times ranging from 10 -3 to 0.5 s, isobutane, neopentane, 2,2-dimethylbutane, isobutyl halides, and tert-butyl halides form C 4 H 9 + ions having the tertiary structure. In n-alkanes, 2-methylbutane, 3-methylpentane, n-butyl halides, and sec-butyl halides, both sec-C 4 H 9 + and t-C 4 H 9 + ions are observed, the sec-C 4 H 9 + ions surviving without rearrangement for at least 0.1 s. However, in the case of the halides, a collision-induced isomerization of the sec-C 4 H 9 + to the t-C 4 H 9 + ions occurs. The efficiency of this process increases with the basicity of the alkyl halide. Radiolysis experiments carried out at atmospheric pressures indicate, in agreement with ICR and solution experiments, that at times as short as 10 -10 s the majority of the i-C 4 H 9 + ions from isobutyl bromide rearrange to the t-C 4 H 9 + structure. On the other hand, in the radiolysis of both n-hexane and 3-methylpentane, the abundance of t-C 4 H 9 + relative to sec-C 4 H 9 + is substantially smaller than that observed in the ICR experiments, and decreases with decreasing collision interval. It is suggested that about 90% of the i-C 4 H 9 + can rearrange to t-C 4 H 9 + by simple 1,2-hydride shift without involving secondary or protonated methylcyclopropane structures as intermediates. 4 figures, 2 tables

  15. Recovery of silver from used X-ray film using alkaline protease from ...

    African Journals Online (AJOL)

    Jane Erike-Etchie

    2016-06-29

    Jun 29, 2016 ... Silver is an important industrial metal used in several areas such as photographic and x-ray films, jewelries, silver ... field of enzyme production. It is widely used in leather industry, diagnosis process, extraction of silver, animal.

  16. Role of organic cations on hybrid halide perovskite CH3NH3PbI3 surfaces

    Science.gov (United States)

    Teng, Qiang; Shi, Ting-Ting; Tian, Ren-Yu; Yang, Xiao-Bao; Zhao, Yu-Jun

    2018-02-01

    Organic-inorganic hybrid halide perovskite CH3NH3PbI3 (MAPbI3) has received rapid progress in power conversion efficiency as promising photovoltaic materials, yet the surface structures and the role of MA cations are not well understood. In this work, we investigated the structural stability and electronic properties of (001) surface of cubic, (001) and (110) surfaces of tetragonal and orthorhombic phases of MAPbI3 with considering the orientation of MA cations, by density functional theory calculations. We demonstrate that the orientation of MA cations has profound consequences on the structural stability and the electronic properties of the surfaces, in contrast to the bulk phases. Compared with the MA-I terminated surfaces, the Pb-I2 terminated ones generally have smaller band gaps and the advantage to enable the photo-excited holes to transfer to the hole-transport materials in both tetragonal and orthorhombic phases. Overall, we suggest that the films with Pb-I2 terminated surfaces would prevail in high performance solar energy absorbers.

  17. Diversity of band gap and photoluminescence properties of lead halide perovskite: A halogen-dependent spectroscopic study

    Science.gov (United States)

    Yu, Wenlei; Jiang, Yunfeng; Zhu, Xiuwei; Luo, Chunhua; Jiang, Kai; Chen, Liangliang; Zhang, Juan

    2018-05-01

    The effects of halogen substitution on microstructure, optical absorption, and phonon modes for perovskite CH3NH3PbX3 (MAPbX3, X = I/Br/Cl) films grown on FTO substrates have been investigated. The X-ray diffraction analysis exhibited good crystallization, and the strong diffraction peak assigned to (1 0 0) c for X = Br/Cl shifted toward a higher angle compared to (1 1 0) t of MAPbI3. Band-gap tuning from 1.63 to 2.37 to 3.11 eV in the I-Br-Cl series can be found due to the halogen effects. These energy values closely match the positions of peak determined from photoluminescence experiments. The remarkable absorption dip and emission peak appear for the MAPbBr3, suggesting higher crystallinity under the same preparation conditions. The wavenumbers of main IR-vibrations slightly decrease with ionic radius of the halogen increasing (in the order of Cl-Br-I), which related to the increasing polarizability. These results provide important progress towards the understanding of the halide role in the realization of high performance MAPbX3-based solar cells.

  18. The electronic structure of the F-center in alkali-halides-The Bethe cluster - lattice

    International Nuclear Information System (INIS)

    Queiroz, S.L.A. de.

    1977-07-01

    The electronic structure of the F-center in alkali-halides with the NaCl structure has been studied using the Bethe Cluster lattice method. The central cluster has been taken as constituted by the vacancy and the nearest- and second-neighbors to it, respectively cations and anions. The optical transitions have been calculated and compared to experimental data on the location of the peak of the F-absorption band. The agreement obtained indicates that this method may be used to study properties of this defect in alkali halides. (Author) [pt

  19. The Electrical and Optical Properties of Organometal Halide Perovskites Relevant to Optoelectronic Performance

    KAUST Repository

    Adinolfi, Valerio

    2017-10-12

    Organometal halide perovskites are under intense study for use in optoelectronics. Methylammonium and formamidinium lead iodide show impressive performance as photovoltaic materials; a premise that has spurred investigations into light-emitting devices and photodetectors. Herein, the optical and electrical material properties of organometal halide perovskites are reviewed. An overview is given on how the material composition and morphology are tied to these properties, and how these properties ultimately affect device performance. Material attributes and techniques used to estimate them are analyzed for different perovskite materials, with a particular focus on the bandgap, mobility, diffusion length, carrier lifetime, and trap-state density.

  20. Aluminum Pitting Corrosion in Halide Media: A Quantum Model and Empirical Evidence

    Science.gov (United States)

    Lashgari, Mohsen; Kianpour, Effat; Mohammadi, Esmaeil

    2013-12-01

    The phenomenon of localized damage of aluminum oxide surface in the presence of halide anions was scrutinized at an atomistic level, through the cluster approach and density functional theory. The phenomenon was also investigated empirically through Tafel polarization plots and scanning electron microscopy. A distinct behavior witnessed in the fluoride medium was justified through the hard-soft acid-base principle. The atomistic investigations revealed the greatest potency for chloride entrance into the metal oxide lattice and rationalized to the severity of damage. The interaction of halide anions with the oxide surface causing some displacements on the position of Al atoms provides a mechanistic insight of the phenomenon.

  1. Band Gap Tuning and Defect Tolerance of Atomically Thin Two- Dimensional Organic-Inorganic Halide Perovskites

    OpenAIRE

    Pandey, Mohnish; Jacobsen, Karsten Wedel; Thygesen, Kristian Sommer

    2016-01-01

    Organic−inorganic halide perovskites have proven highly successful for photovoltaics but suffer from low stability, which deteriorates their performance over time. Recent experiments have demonstrated that low dimensional phases of the hybrid perovskites may exhibit improved stability. Here we report first-principles calculations for isolated monolayers of the organometallic halide perovskites (C4H9NH3)2MX2Y2, where M = Pb, Ge, Sn and X,Y = Cl, Br, I. The band gaps computed using the GLLB-SC ...

  2. Building up an electrocatalytic activity scale of cathode materials for organic halide reductions

    International Nuclear Information System (INIS)

    Bellomunno, C.; Bonanomi, D.; Falciola, L.; Longhi, M.; Mussini, P.R.; Doubova, L.M.; Di Silvestro, G.

    2005-01-01

    A wide investigation on the electrochemical activity of four model organic bromides has been carried out in acetonitrile on nine cathodes of widely different affinity for halide anions (Pt, Zn, Hg, Sn, Bi, Pb, Au, Cu, Ag), and the electrocatalytic activities of the latter have been evaluated with respect to three possible inert reference cathode materials, i.e. glassy carbon, boron-doped diamond, and fluorinated boron-doped diamond. A general electrocatalytic activity scale for the process is proposed, with a discussion on its modulation by the configuration of the reacting molecule, and its connection with thermodynamic parameters accounting for halide adsorption

  3. A mild and efficient procedure for the synthesis of ethers from various alkyl halides

    Directory of Open Access Journals (Sweden)

    Mosstafa Kazemi

    2013-10-01

    Full Text Available A simple, mild and practical procedure has been developed for the synthesis of symmetrical and unsymmetrical ethers by using DMSO, TBAI in the presence of K2CO3. We extended the utility of Potassium carbonate as an efficient base for the preparation of ethers. A wide range of alkyl aryl and dialkyl ethers are synthezied from treatment of aliphatic alcohols and phenols with various alkyl halides in the prescence of efficient base Potassium carbonate. Secondary alkyl halides were easily converted to corresponding ethers in releatively good yields . This is a mild, simple and practical procedure for the preparation of ethers in high yields and suitable times under mild condition.

  4. Designing mixed metal halide ammines for ammonia storage using density functional theory and genetic algorithms

    DEFF Research Database (Denmark)

    Jensen, Peter Bjerre; Lysgaard, Steen; Quaade, Ulrich J.

    2014-01-01

    electrolyte membrane fuel cells (PEMFC). We use genetic algorithms (GAs) to search for materials containing up to three different metals (alkaline-earth, 3d and 4d) and two different halides (Cl, Br and I) – almost 27000 combinations, and have identified novel mixtures, with significantly improved storage......Metal halide ammines have great potential as a future, high-density energy carrier in vehicles. So far known materials, e.g. Mg(NH3)6Cl2 and Sr(NH3)8Cl2, are not suitable for automotive, fuel cell applications, because the release of ammonia is a multi-step reaction, requiring too much heat...

  5. Improved catalytic properties of halohydrin dehalogenase by modification of the halide-binding site.

    Science.gov (United States)

    Tang, Lixia; Torres Pazmiño, Daniel E; Fraaije, Marco W; de Jong, René M; Dijkstra, Bauke W; Janssen, Dick B

    2005-05-03

    Halohydrin dehalogenase (HheC) from Agrobacterium radiobacter AD1 catalyzes the dehalogenation of vicinal haloalcohols by an intramolecular substitution reaction, resulting in the formation of the corresponding epoxide, a halide ion, and a proton. Halide release is rate-limiting during the catalytic cycle of the conversion of (R)-p-nitro-2-bromo-1-phenylethanol by the enzyme. The recent elucidation of the X-ray structure of HheC showed that hydrogen bonds between the OH group of Tyr187 and between the Odelta1 atom of Asn176 and Nepsilon1 atom of Trp249 could play a role in stabilizing the conformation of the halide-binding site. The possibility that these hydrogen bonds are important for halide binding and release was studied using site-directed mutagenesis. Steady-state kinetic studies revealed that mutant Y187F, which has lost both hydrogen bonds, has a higher catalytic activity (k(cat)) with two of the three tested substrates compared to the wild-type enzyme. Mutant W249F also shows an enhanced k(cat) value with these two substrates, as well as a remarkable increase in enantiopreference for (R)-p-nitro-2-bromo-1-phenylethanol. In case of a mutation at position 176 (N176A and N176D), a 1000-fold lower catalytic efficiency (k(cat)/K(m)) was obtained, which is mainly due to an increase of the K(m) value of the enzyme. Pre-steady-state kinetic studies showed that a burst of product formation precedes the steady state, indicating that halide release is still rate-limiting for mutants Y187F and W249F. Stopped-flow fluorescence experiments revealed that the rate of halide release is 5.6-fold higher for the Y187F mutant than for the wild-type enzyme and even higher for the W249F enzyme. Taken together, these results show that the disruption of two hydrogen bonds around the halide-binding site increases the rate of halide release and can enhance the overall catalytic activity of HheC.

  6. Manganese-Catalyzed Cross-Coupling of Aryl Halides and Grignard Reagents by a Radical Mechanism

    DEFF Research Database (Denmark)

    Antonacci, Giuseppe; Ahlburg, Andreas; Fristrup, Peter

    2017-01-01

    The substrate scope and the mechanism have been investigated for the MnCl2-catalyzed cross-coupling reaction between aryl halides and Grignard reagents. The transformation proceeds rapidly and in good yield when the aryl halide component is an aryl chloride containing a cyano or an ester group....... Two radical-clock experiments were carried out, and in both cases an intermediate aryl radical was successfully trapped. The cross-coupling reaction is therefore believed to proceed by an SRN1 mechanism, with a triorganomanganate complex serving as the most likely nucleophile and single-electron donor...

  7. A Cluster-Bethe lattice treatment for the F-center in alkali-halides

    International Nuclear Information System (INIS)

    Queiroz, S.L.A. de; Koiller, B.; Maffeo, B.; Brandi, H.S.

    1977-01-01

    The electronic structure of the F-center in alkali-halides with the NaCl structure has been studied using the Cluster-Bethe lattice method. The central cluster has been taken as constituted by the vacancy and the nearest- and second- neighbors to it, respectively, cations and anions. The optical transitions have been calculated and compared to experimental data on the location of the peak of the F-absorption band. The agreement obtained indicates that this method may be used to study properties of this defect in alkali halides [pt

  8. Crossover And MTF Characteristics Of A Tabular-Grain X-Ray Film

    Science.gov (United States)

    Huff, K. E.; Wagner, P. W.

    1984-08-01

    An orthochromatic x-ray film made with tabular silver halide grains has a significantly higher MTF when exposed with green-emitting intensifying screens than do conventional films with similar sensitometric properties. The primary reason for the improved MTF is a decrease in the amount of crossover exposure, i.e., exposure by light that has crossed the support one or more times. Two well-established sensitometric procedures for measuring crossover have been compared. One produces results accurate enough for calculations of MTF relationships. Calculated MTF relationships for tabulargrain and conventional films are compared with measured values.

  9. An interactive program for digitization of seabed photographs

    Digital Repository Service at National Institute of Oceanography (India)

    Ramprasad, T.; Sharma, R.

    A program for dignitization of seabed photographs to compute coverage and abundance of polymetallic nodules is developed. Since the objects in the seabed photograph are partially covered by thin sediment layer, the automatic scanning devices may...

  10. Time perception of action photographs is more precise than that of still photographs.

    Science.gov (United States)

    Moscatelli, Alessandro; Polito, Laura; Lacquaniti, Francesco

    2011-04-01

    A photograph of an action contains implicit information about the depicted motion. Previous studies using either psychophysics or neuroimaging suggested that the neural processing of implied-motion images shares some features of real-motion processing. According to the hypothesis that the target depicted in photographs with implied motion is mentally represented as continuing in motion, such kind of photographs should be processed by the brain similarly to the individual frames of a running movie. In order to decode the functional significance of a movie, we must be able to estimate the duration of each frame and the time interval between successive frames as precisely as possible. Therefore, under naturalistic conditions, one would expect that the precision of time duration estimates is higher for action pictures than for still pictures. To test this prediction, we asked human observers to compare the variable duration of test photographs with the reference duration of their scrambled version. We found that, as expected, the duration of photographs with implied motion was discriminated better than the duration of photographs without implied motion. We also found that the average reaction time for the discrimination of photographs with implied motion was longer than that for photographs without implied motion, suggesting that the processing of implied motion involves longer and/or slower neural routes to compute time duration. This longer processing may depend on the engagement of two visual systems in parallel, one for processing form and the other one for processing implied motion. The perceptual decision about time duration would occur after the convergence of signals from these two pathways.

  11. Spectroscopic investigation of indium halides as substitudes of mercury in low pressure discharges for lighting applications

    Energy Technology Data Exchange (ETDEWEB)

    Briefi, Stefan

    2012-05-22

    Low pressure discharges with indium halides as radiator are discussed as substitutes for hazardous mercury in conventional fluorescent lamps. In this work, the applicability of InBr and InCl in a low pressure discharge light source is investigated. The aim is to identify and understand the physical processes which determine the discharge characteristics and the efficiency of the generated near-UV emission of the indium halide molecule and of the indium atom which is created due to dissociation processes in the plasma. As discharge vessels sealed cylindrical quartz glass tubes which contain a defined amount of indium halide and a rare gas are used. Preliminary investigations showed that for a controlled variation of the indium halide density a well-defined cold spot setup is mandatory. This was realized in the utilized experimental setup. The use of metal halides raises the issue, that power coupling by internal electrodes is not possible as the electrodes would quickly be eroded by the halides. The comparison of inductive and capacitive RF-coupling with external electrodes revealed that inductively coupled discharges provide higher light output and much better long term stability. Therefore, all investigations are carried out using inductive RF-coupling. The diagnostic methods optical emission and white light absorption spectroscopy are applied. As the effects of absorption-signal saturation and reabsorption of emitted radiation within the plasma volume could lead to an underestimation of the determined population densities by orders of magnitude, these effects are considered in the data evaluation. In order to determine the electron temperature and the electron density from spectroscopic measurements, an extended corona model as population model of the indium atom has been set up. A simulation of the molecular emission spectra has been implemented to investigate the rovibrational population processes of the indium halide molecules. The impact of the cold spot

  12. New uses of shadow enhancement. [interpretation of geologic structures from photographic or scanner imagery of Colorado

    Science.gov (United States)

    Lee, K. (Principal Investigator); Sawatzky, D. L.

    1974-01-01

    The author has identified the following significant results. Shadow enhancement of topographic linears in photographic or scanner images is a valuable tool for interpretation of geologic structures. Whether linears will be enhanced or subdued depends on sun angle and azimuth. The relationship of the sun's attitude to topographic slopes determines which trends are available for interpretation in existing imagery, and it can be used to select the time of day, surface properties, and film and filter characteristics in planning aircraft flights or satellite orbital passes. The technique of selective shadow enhancement can be applied to all photographic or imaging experiments, but its best for snow-covered scenes, side-looking radar images, and painted relief models.

  13. Controlled Crystal Grain Growth in Mixed Cation-Halide Perovskite by Evaporated Solvent Vapor Recycling Method for High Efficiency Solar Cells.

    Science.gov (United States)

    Numata, Youhei; Kogo, Atsushi; Udagawa, Yosuke; Kunugita, Hideyuki; Ema, Kazuhiro; Sanehira, Yoshitaka; Miyasaka, Tsutomu

    2017-06-07

    We developed a new and simple solvent vapor-assisted thermal annealing (VA) procedure which can reduce grain boundaries in a perovskite film for fabricating highly efficient perovskite solar cells (PSCs). By recycling of solvent molecules evaporated from an as-prepared perovskite film as a VA vapor source, named the pot-roast VA (PR-VA) method, finely controlled and reproducible device fabrication was achieved for formamidinium (FA) and methylammonium (MA) mixed cation-halide perovskite (FAPbI 3 ) 0.85 (MAPbBr 3 ) 0.15 . The mixed perovskite was crystallized on a low-temperature prepared brookite TiO 2 mesoporous scaffold. When exposed to very dilute solvent vapor, small grains in the perovskite film gradually unified into large grains, resulting in grain boundaries which were highly reduced and improvement of photovoltaic performance in PSC. PR-VA-treated large grain perovskite absorbers exhibited stable photocurrent-voltage performance with high fill factor and suppressed hysteresis, achieving the best conversion efficiency of 18.5% for a 5 × 5 mm 2 device and 15.2% for a 1.0 × 1.0 cm 2 device.

  14. 3D PHOTOGRAPHS IN CULTURAL HERITAGE

    Directory of Open Access Journals (Sweden)

    W. Schuhr

    2013-07-01

    Full Text Available This paper on providing "oo-information" (= objective object-information on cultural monuments and sites, based on 3D photographs is also a contribution of CIPA task group 3 to the 2013 CIPA Symposium in Strasbourg. To stimulate the interest in 3D photography for scientists as well as for amateurs, 3D-Masterpieces are presented. Exemplary it is shown, due to their high documentary value ("near reality", 3D photography support, e.g. the recording, the visualization, the interpretation, the preservation and the restoration of architectural and archaeological objects. This also includes samples for excavation documentation, 3D coordinate calculation, 3D photographs applied for virtual museum purposes and as educational tools. In addition 3D photography is used for virtual museum purposes, as well as an educational tool and for spatial structure enhancement, which in particular holds for inscriptions and in rock arts. This paper is also an invitation to participate in a systematic survey on existing international archives of 3D photographs. In this respect it is also reported on first results, to define an optimum digitization rate for analog stereo views. It is more than overdue, in addition to the access to international archives for 3D photography, the available 3D photography data should appear in a global GIS(cloud-system, like on, e.g., google earth. This contribution also deals with exposing new 3D photographs to document monuments of importance for Cultural Heritage, including the use of 3D and single lense cameras from a 10m telescope staff, to be used for extremely low earth based airborne 3D photography, as well as for "underwater staff photography". In addition it is reported on the use of captive balloon and drone platforms for 3D photography in Cultural Heritage. It is liked to emphasize, the still underestimated 3D effect on real objects even allows, e.g., the spatial perception of extremely small scratches as well as of nuances in

  15. 8 CFR 236.5 - Fingerprints and photographs.

    Science.gov (United States)

    2010-01-01

    ... 8 Aliens and Nationality 1 2010-01-01 2010-01-01 false Fingerprints and photographs. 236.5 Section... to Order of Removal § 236.5 Fingerprints and photographs. Every alien 14 years of age or older... photographs shall be made available to Federal, State, and local law enforcement agencies upon request to the...

  16. Best of Adobe Photoshop techniques and images from professional photographers

    CERN Document Server

    Hurter, Bill

    2006-01-01

    Bill Hurter is the editor of ""Rangefinder"" magazine, the former editor of ""Petersen's PhotoGraphic,"" and the author of ""The Best of Wedding Photography, Group Portrait Photography Handbook, The Portrait Photographer's Guide to Posing, ""and ""Portrait Photographer's Handbook. ""He lives in Santa Monica, California.

  17. The aesthetic appeal of depth of field in photographs

    NARCIS (Netherlands)

    Zhang, T.; Nefs, H.T.; Redi, J.; Heynderickx, I.E.J.

    2014-01-01

    We report here how depth of field (DOF) affects the aesthetic appeal of photographs for different content categories. 339 photographs spanning eight categories were selected from Flickr, Google+, and personal collections. First, we classified the 339 photographs into three levels of depth of field:

  18. Using Photographs to Integrate Liberal Arts Learning in Business Education

    Science.gov (United States)

    Madden, Laura T.; Smith, Anne D.

    2015-01-01

    The inclusion of photographic approaches in the business classroom can incorporate missing elements of liberal education into business education, which were highlighted in a recent Carnegie study of undergraduate business education. Building on photographic methods in social science research, we identify three categories of photographic approaches…

  19. 7 CFR 500.9 - Photographs for news or advertising.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 6 2010-01-01 2010-01-01 false Photographs for news or advertising. 500.9 Section 500... for news or advertising. Photographs for news purposes may be taken at the USNA without prior permission. Photographs for advertising and other commercial purposes may be taken, but only with the prior...

  20. Images of the Great Depression: A Photographic Essay.

    Science.gov (United States)

    Stevens, Robert L.; Fogel, Jared A.

    2001-01-01

    Provides background information on the Farm Security Administration (FSA) and the photographic section of the FSA. Identifies six photographers and features three photographers (Walker Evans, Dorothea Lange, and Ben Shahn) who were recruited to document farm conditions. Discusses using FSA photos in the classroom and provides lesson plans to help…

  1. Recognition Memory for Movement in Photographs: A Developmental Study.

    Science.gov (United States)

    Futterweit, Lorelle R.; Beilin, Harry

    1994-01-01

    Investigated whether children's recognition memory for movement in photographs is distorted forward in the direction of implied motion. When asked whether the second photograph was the same as or different from the first, subjects made more errors for test photographs showing the action slightly forward in time, compared with slightly backward in…

  2. Water-Induced Dimensionality Reduction in Metal-Halide Perovskites

    KAUST Repository

    Turedi, Bekir; Lee, Kwangjae; Dursun, Ibrahim; Alamer, Badriah Jaber; Wu, Zhennan; Alarousu, Erkki; Mohammed, Omar F.; Cho, Namchul; Bakr, Osman

    2018-01-01

    . Here we employ water to directly transform films of the three-dimensional (3D) perovskite CsPbBr3 to stable two-dimensional (2D) perovskite-related CsPb2Br5. A sequential dissolution-recrystallization process governs this water induced transformation

  3. Materials Processing Routes to Trap-Free Halide Perovskites

    KAUST Repository

    Buin, Andrei

    2014-11-12

    © 2014 American Chemical Society. Photovoltaic devices based on lead iodide perovskite films have seen rapid advancements, recently achieving an impressive 17.9% certified solar power conversion efficiency. Reports have consistently emphasized that the specific choice of growth conditions and chemical precursors is central to achieving superior performance from these materials; yet the roles and mechanisms underlying the selection of materials processing route is poorly understood. Here we show that films grown under iodine-rich conditions are prone to a high density of deep electronic traps (recombination centers), while the use of a chloride precursor avoids the formation of key defects (Pb atom substituted by I) responsible for short diffusion lengths and poor photovoltaic performance. Furthermore, the lowest-energy surfaces of perovskite crystals are found to be entirely trap-free, preserving both electron and hole delocalization to a remarkable degree, helping to account for explaining the success of polycrystalline perovskite films. We construct perovskite films from I-poor conditions using a lead acetate precursor, and our measurement of a long (600 ± 40 nm) diffusion length confirms this new picture of the importance of growth conditions.

  4. Oscilloscope trace photograph digitizing system (TRACE)

    International Nuclear Information System (INIS)

    Richards, M.; Dabbs, R.D.

    1977-10-01

    The digitizing system allows digitization of photographs or sketches of waveforms and then the computer is used to reduce and analyze the data. The software allows for alignment, calibration, removal of baselines, removal of unwanted points and addition of new points which makes for a fairly versatile system as far as data reduction and manipulation are concerned. System considerations are introduced first to orient the potential user to the process of digitizing information. The start up and actual commands for TRACE are discussed. Detailed descriptions of each subroutine and program section are also provided. Three general examples of typical photographs are included. A partial listing of FAWTEK is made available. Once suitable arrays that contain the data are arranged, ''GO FA'' (active FAWTEK) and many mathematical operations to further analyze the data may be performed

  5. ECR plasma photographs as a plasma diagnostic

    Energy Technology Data Exchange (ETDEWEB)

    Racz, R; Biri, S; Palinkas, J [Institute of Nuclear Research (ATOMKI), H-4026 Debrecen, Bem ter 18/c (Hungary)

    2011-04-15

    Low, medium or highly charged ions delivered by electron cyclotron resonance (ECR) ion sources all are produced in the ECR plasma. In order to study such plasmas, high-resolution visible light plasma photographs were taken at the ATOMKI ECR ion source. An 8 megapixel digital camera was used to photograph plasmas made from He, methane, N, O, Ne, Ar, Kr, Xe gases and from their mixtures. The analysis of the photo series gave many qualitative and some valuable physical information on the nature of ECR plasmas. A comparison was made between the plasma photos and computer simulations, and conclusions were drawn regarding the cold electron component of the plasma. The warm electron component of similar simulation was compared with x-ray photos emitted by plasma ions. While the simulations are in good agreement with the photos, a significant difference was found between the spatial distribution of the cold and warm electrons.

  6. The Cambridge photographic atlas of galaxies

    CERN Document Server

    König, Michael

    2017-01-01

    Galaxies - the Milky Way's siblings - offer a surprising variety of forms and colours. Displaying symmetrical spiral arms, glowing red nebulae or diffuse halos, even the image of a galaxy can reveal much about its construction. All galaxies consist of gas, dust and stars, but the effects of gravity, dark matter and the interaction of star formation and stellar explosions all influence their appearances. This volume showcases more than 250 of the most beautiful galaxies within an amateur's reach and uses them to explain current astrophysical research. It features fantastic photographs, unique insights into our knowledge, tips on astrophotography and essential facts and figures based on the latest science. From the Andromeda Galaxy to galaxy clusters and gravitational lenses, the nature of galaxies is revealed through these stunning amateur photographs. This well illustrated reference atlas deserves a place on the bookshelves of astronomical imagers, observers and armchair enthusiasts.

  7. Determination of the structural phase and octahedral rotation angle in halide perovskites

    Science.gov (United States)

    dos Reis, Roberto; Yang, Hao; Ophus, Colin; Ercius, Peter; Bizarri, Gregory; Perrodin, Didier; Shalapska, Tetiana; Bourret, Edith; Ciston, Jim; Dahmen, Ulrich

    2018-02-01

    A key to the unique combination of electronic and optical properties in halide perovskite materials lies in their rich structural complexity. However, their radiation sensitive nature limits nanoscale structural characterization requiring dose efficient microscopic techniques in order to determine their structures precisely. In this work, we determine the space-group and directly image the Br halide sites of CsPbBr3, a promising material for optoelectronic applications. Based on the symmetry of high-order Laue zone reflections of convergent-beam electron diffraction, we identify the tetragonal (I4/mcm) structural phase of CsPbBr3 at cryogenic temperature. Electron ptychography provides a highly sensitive phase contrast measurement of the halide positions under low electron-dose conditions, enabling imaging of the elongated Br sites originating from the out-of-phase octahedral rotation viewed along the [001] direction of I4/mcm persisting at room temperature. The measurement of these features and comparison with simulations yield an octahedral rotation angle of 6.5°(±1.5°). The approach demonstrated here opens up opportunities for understanding the atomic scale structural phenomena applying advanced characterization tools on a wide range of radiation sensitive halide-based all-inorganic and hybrid organic-inorganic perovskites.

  8. Luminescent decay and spectra of impurity-activated alkali halides under high pressure

    International Nuclear Information System (INIS)

    Klick, D.I.

    1977-01-01

    The effect of high pressure on the luminescence of alkali halides doped with the transition-metal ions Cu + and Ag + and the heavy-metal ions In + and Tl + was investigated to 140 kbar. Measurement of spectra allowed the prediction of kinetic properties, and the predictions agree with lifetime data

  9. 2-D images of the metal-halide lamp obtained by experiment and model

    NARCIS (Netherlands)

    Flikweert, A.J.; Beks, M.L.; Nimalasuriya, T.; Kroesen, G.M.W.; Mullen, van der J.J.A.M.; Stoffels, W.W.

    2008-01-01

    The metal-halide lamp shows color segregation caused by diffusion and convection. Two-dimensional imaging of the arc discharge under varying gravity conditions aids in the understanding of the flow phenomena. In this paper, we show results obtained by experiments and by numerical simulations in

  10. Organometallic halide perovskite single crystals having low deffect density and methods of preparation thereof

    KAUST Repository

    Bakr, Osman; Shi, Dong

    2016-01-01

    The present disclosure presents a method of making a single crystal organometallic halide perovskites, with the formula: AMX3, wherein A is an organic cation, M is selected from the group consisting of: Pb, Sn, Cu, Ni, Co, Fe, Mn, Pd, Cd, Ge, and Eu

  11. Advancement on Lead-Free Organic-Inorganic Halide Perovskite Solar Cells: A Review.

    Science.gov (United States)

    Sani, Faruk; Shafie, Suhaidi; Lim, Hong Ngee; Musa, Abubakar Ohinoyi

    2018-06-14

    Remarkable attention has been committed to the recently discovered cost effective and solution processable lead-free organic-inorganic halide perovskite solar cells. Recent studies have reported that, within five years, the reported efficiency has reached 9.0%, which makes them an extremely promising and fast developing candidate to compete with conventional lead-based perovskite solar cells. The major challenge associated with the conventional perovskite solar cells is the toxic nature of lead (Pb) used in the active layer of perovskite material. If lead continues to be used in fabricating solar cells, negative health impacts will result in the environment due to the toxicity of lead. Alternatively, lead free perovskite solar cells could give a safe way by substituting low-cost, abundant and non toxic material. This review focuses on formability of lead-free organic-inorganic halide perovskite, alternative metal cations candidates to replace lead (Pb), and possible substitutions of organic cations, as well as halide anions in the lead-free organic-inorganic halide perovskite architecture. Furthermore, the review gives highlights on the impact of organic cations, metal cations and inorganic anions on stability and the overall performance of lead free perovskite solar cells.

  12. Can Ferroelectric Polarization Explain the High Performance of Hybrid Halide Perovskite Solar Cells?

    NARCIS (Netherlands)

    Sherkar, Tejas; Koster, L. Jan Anton

    The power conversion efficiency of photovoltaic cells based on the use of hybrid halide perovskites, CH3NH3PbX3 (X = Cl, Br, I), now exceeds 20%. Recently, it was suggested that this high performance originates from the presence of ferroelectricity in the perovskite, which is hypothesized to lower

  13. Ligand-free, palladium-catalyzed dihydrogen generation from TMDS: dehalogenation of aryl halides on water.

    Science.gov (United States)

    Bhattacharjya, Anish; Klumphu, Piyatida; Lipshutz, Bruce H

    2015-03-06

    A mild and environmentally attractive dehalogenation of functionalized aryl halides has been developed using nanoparticles formed from PdCl2 in the presence of tetramethyldisiloxane (TMDS) on water. The active catalyst and reaction medium can be recycled. This method can also be applied to cascade reactions in a one-pot sequence.

  14. Radiation chemistry of hydrocarbon and alkyl halide systems. Progress report, August 1, 1977--August 1, 1978

    International Nuclear Information System (INIS)

    Hanrahan, R.J.

    1978-01-01

    Progress of experimental work is reported on pulse radiolysis of simple alkyl halides in the gas phase, gas phase radiolysis of CHF 3 -CH 3 I mixtures, gamma radiolysis of the system CO/H 2 , and improvements in equipment and facilities

  15. Direct ToF-SIMS analysis of organic halides and amines on TLC plates

    Energy Technology Data Exchange (ETDEWEB)

    Parent, Alexander A. [Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT 84602 (United States); Anderson, Thomas M. [Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT 84602 (United States); Michaelis, David J. [Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT 84602 (United States); Jiang, Guilin [Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT 84602 (United States); Savage, Paul B. [Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT 84602 (United States); Linford, Matthew R. [Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT 84602 (United States)]. E-mail: mrlinford@chem.byu.edu

    2006-07-30

    It has been reported that: 'direct analysis of thin layer chromatography (TLC) plates with secondary ion mass spectrometry (SIMS) yields no satisfactory results' (J. Chromatogr. A 1084 (2005) 113-118). While this statement appears to be true in general, we have identified two important classes of compounds, organic halides and amines, that appear to yield to such direct analyses. For example, five organic halides with diverse structures were eluted on normal phase TLC plates. In all cases the halide signals in the negative ion time-of-flight secondary ion mass spectrometry (ToF-SIMS) spectra were notably stronger than the background signals. Similarly, a series of five organic amines with diverse structures were directly analyzed by positive ion ToF-SIMS. In all but one of the spectra characteristic, and sometimes even quasi-molecular ions, were observed. Most likely, the good halide ion yields are largely a function of the electronegativity of the halogens. We also propose that direct analysis of amines on normal phase silica gel is facilitated by the acidity, i.e., proton donation, of surface silanol groups.

  16. Direct ToF-SIMS analysis of organic halides and amines on TLC plates

    International Nuclear Information System (INIS)

    Parent, Alexander A.; Anderson, Thomas M.; Michaelis, David J.; Jiang, Guilin; Savage, Paul B.; Linford, Matthew R.

    2006-01-01

    It has been reported that: 'direct analysis of thin layer chromatography (TLC) plates with secondary ion mass spectrometry (SIMS) yields no satisfactory results' (J. Chromatogr. A 1084 (2005) 113-118). While this statement appears to be true in general, we have identified two important classes of compounds, organic halides and amines, that appear to yield to such direct analyses. For example, five organic halides with diverse structures were eluted on normal phase TLC plates. In all cases the halide signals in the negative ion time-of-flight secondary ion mass spectrometry (ToF-SIMS) spectra were notably stronger than the background signals. Similarly, a series of five organic amines with diverse structures were directly analyzed by positive ion ToF-SIMS. In all but one of the spectra characteristic, and sometimes even quasi-molecular ions, were observed. Most likely, the good halide ion yields are largely a function of the electronegativity of the halogens. We also propose that direct analysis of amines on normal phase silica gel is facilitated by the acidity, i.e., proton donation, of surface silanol groups

  17. Electron detachment energies in high-symmetry alkali halide solvated-electron anions

    Science.gov (United States)

    Anusiewicz, Iwona; Berdys, Joanna; Simons, Jack; Skurski, Piotr

    2003-07-01

    We decompose the vertical electron detachment energies (VDEs) in solvated-electron clusters of alkali halides in terms of (i) an electrostatic contribution that correlates with the dipole moment (μ) of the individual alkali halide molecule and (ii) a relaxation component that is related to the polarizability (α) of the alkali halide molecule. Detailed numerical ab initio results for twelve species (MX)n- (M=Li,Na; X=F,Cl,Br; n=2,3) are used to construct an interpolation model that relates the clusters' VDEs to their μ and α values as well as a cluster size parameter r that we show is closely related to the alkali cation's ionic radius. The interpolation formula is then tested by applying it to predict the VDEs of four systems [i.e., (KF)2-, (KF)3-, (KCl)2-, and (KCl)3-] that were not used in determining the parameters of the model. The average difference between the model's predicted VDEs and the ab initio calculated electron binding energies is less than 4% (for the twelve species studied). It is concluded that one can easily estimate the VDE of a given high-symmetry solvated electron system by employing the model put forth here if the α, μ and cation ionic radii are known. Alternatively, if VDEs are measured for an alkali halide cluster and the α and μ values are known, one can estimate the r parameter, which, in turn, determines the "size" of the cluster anion.

  18. Highly Efficient Broadband Yellow Phosphor Based on Zero-Dimensional Tin Mixed-Halide Perovskite.

    Science.gov (United States)

    Zhou, Chenkun; Tian, Yu; Yuan, Zhao; Lin, Haoran; Chen, Banghao; Clark, Ronald; Dilbeck, Tristan; Zhou, Yan; Hurley, Joseph; Neu, Jennifer; Besara, Tiglet; Siegrist, Theo; Djurovich, Peter; Ma, Biwu

    2017-12-27

    Organic-inorganic hybrid metal halide perovskites have emerged as a highly promising class of light emitters, which can be used as phosphors for optically pumped white light-emitting diodes (WLEDs). By controlling the structural dimensionality, metal halide perovskites can exhibit tunable narrow and broadband emissions from the free-exciton and self-trapped excited states, respectively. Here, we report a highly efficient broadband yellow light emitter based on zero-dimensional tin mixed-halide perovskite (C 4 N 2 H 14 Br) 4 SnBr x I 6-x (x = 3). This rare-earth-free ionically bonded crystalline material possesses a perfect host-dopant structure, in which the light-emitting metal halide species (SnBr x I 6-x 4- , x = 3) are completely isolated from each other and embedded in the wide band gap organic matrix composed of C 4 N 2 H 14 Br - . The strongly Stokes-shifted broadband yellow emission that peaked at 582 nm from this phosphor, which is a result of excited state structural reorganization, has an extremely large full width at half-maximum of 126 nm and a high photoluminescence quantum efficiency of ∼85% at room temperature. UV-pumped WLEDs fabricated using this yellow emitter together with a commercial europium-doped barium magnesium aluminate blue phosphor (BaMgAl 10 O 17 :Eu 2+ ) can exhibit high color rendering indexes of up to 85.

  19. Kinetics of halide release of haloalkane dehalogenase : Evidence for a slow conformational change

    NARCIS (Netherlands)

    Schanstra, JP; Janssen, DB; Schanstra, Joost P.

    1996-01-01

    Haloalkane dehalogenase converts haloalkanes to their corresponding alcohols and halides, The reaction mechanism involves the formation of a covalent alkyl-enzyme complex which is hydrolyzed by water. The active site is a hydrophobic cavity buried between the main domain and the cap domain of the

  20. Behaviour of alkali halides as materials for optical components of high power lasers

    International Nuclear Information System (INIS)

    Apostol, D.I.; Mihailescu, N.I.; Ghiordanescu, V.; Nistor, C.L.; Nistor, V.S.; Teodorescu, V.; Voda, M.

    1978-01-01

    The physical phenomena taking place in alkali halides when a CO 2 laser radiation is passing through have been reviewed. A special emphasis has been put on the specific qualities which such materials should have for being used as components for high power lasers. (author)

  1. Correlated linear response calculations of the C6 dispersion coefficients of hydrogen halides

    Czech Academy of Sciences Publication Activity Database

    Sauer, S. P. A.; Paidarová, Ivana

    2007-01-01

    Roč. 3, 2-4 (2007), s. 399-421 ISSN 1574-0404 R&D Projects: GA AV ČR IAA401870702 Institutional research plan: CEZ:AV0Z40400503 Keywords : hydrogen halides * C6 dospersion coefficients * van der Waals coefficients * polarizability at imaginary frequences * SOPPA Subject RIV: CF - Physical ; Theoretical Chemistry

  2. REPLACEMENT OF TRYPTOPHAN RESIDUES IN HALOALKANE DEHALOGENASE REDUCES HALIDE BINDING AND CATALYTIC ACTIVITY

    NARCIS (Netherlands)

    KENNES, C; PRIES, F; KROOSHOF, GH; BOKMA, E; Kingma, Jacob; JANSSEN, DB

    1995-01-01

    Haloalkane dehalogenase catalyzes the hydrolytic cleavage of carbon-halogen bonds in short-chain haloalkanes. Two tryptophan residues of the enzyme (Trp125 and Trp175) form a halide-binding site in the active-site cavity, and were proposed to play a role in catalysis. The function of these residues

  3. Relationship between thermoluminescence and X-ray induced luminescence in alkali halides

    International Nuclear Information System (INIS)

    Aguilar, M.; Lopez, F.J.; Jaque, F.

    1978-01-01

    The wavelength spectra of thermoluminescence and X-ray induced luminescence in pure and divalent cation doped alkali halides, in the temperature range LNT-RT have been studied. The more important conclusion is that the wavelength spectra in both cases are very similar. This allows a new point of view to be presented on thermoluminescence mechanisms. (author)

  4. Chemistry of gaseous lower-valent actinide halides. Technical progress report

    International Nuclear Information System (INIS)

    Hildenbrand, D.L.

    1984-01-01

    Objective is to provide thermochemical data for key actinide halide and oxyhalide systems. Progress is reported on bond dissociation energies of gaseous ThCl 4 , ThCl 3 , ThCl 2 , and ThCl; bond dissociation energies of ruthenium fluorides; and mass spectroscopy of UF 6

  5. Charge-charge liquid structure factor and the freezing of alkali halides

    International Nuclear Information System (INIS)

    March, N.H.; Tosi, M.P.

    1980-10-01

    The peak height of the charge-charge liquid structure factor Ssub(QQ) in molten alkali halides is proposed as a criterion for freezing. Available data on molten alkali chlorides, when extrapolated to the freezing point suggests Ssub(QQ)sup(max) approximately 5. (author)

  6. A model for additive transport in metal halide lamps containing mercury and dysprosium tri-iodide

    NARCIS (Netherlands)

    Beks, M.L.; Haverlag, M.; Mullen, van der J.J.A.M.

    2008-01-01

    The distribution of additives in a metal halide lamp is examined through numerical modelling. A model for a lamp containing sodium iodide additives has been modified to study a discharge containing dysprosium tri-iodide salts. To study the complex chemistry the method of Gibbs minimization is used

  7. Electrochemical specific adsorption of halides on Cu 111, 100, and 211: A Density Functional Theory study

    International Nuclear Information System (INIS)

    McCrum, Ian T.; Akhade, Sneha A.; Janik, Michael J.

    2015-01-01

    The specific adsorption of ions onto electrode surfaces can affect electrocatalytic reactions. Density functional theory is used to investigate the specific adsorption of aqueous F − , Cl − , Br − , and I − onto Cu (111), (100), and (211) surfaces. The adsorption is increasingly favorable in the order of F − < Cl − < Br − < I − . The adsorption has a weak dependence on the surface facet, with adsorption most favorable on Cu (100) and least favorable on Cu (111). Potential ranges where specific adsorption would be expected on each facet are reported. The thermodynamics of bulk copper halide (CuX, CuX 2 ) formation are also investigated as a function of potential. CuX formation occurs at potentials slightly more positive of halide specific adsorption and of copper oxidation in aqueous electrolytes. Specifically adsorbed halides and bulk CuX may be present during a variety of electrochemical reactions carried out over a Cu electrode in halide containing electrolyte solutions

  8. Transport phenomena in metal-halide lamps : a poly-diagnostic study

    NARCIS (Netherlands)

    Nimalasuriya, T.

    2007-01-01

    Worldwide about 20% of all electricity is used for lighting. It is therefore of great interest to develop a lamp that has high e±cacy, good colour rendering and long lifetime. The metal-halide lamp is a gas discharge lamp that meets all these demands. Unfortunately there are still issues with this

  9. Students' Understanding of Alkyl Halide Reactions in Undergraduate Organic Chemistry

    Science.gov (United States)

    Cruz-Ramírez de Arellano, Daniel; Towns, Marcy H.

    2014-01-01

    Organic chemistry is an essential subject for many undergraduate students completing degrees in science, engineering, and pre-professional programs. However, students often struggle with the concepts and skills required to successfully solve organic chemistry exercises. Since alkyl halides are traditionally the first functional group that is…

  10. Epitaxial Growth of a Methoxy-Functionalized Quaterphenylene on Alkali Halide Surfaces

    DEFF Research Database (Denmark)

    Balzer, Frank; Sun, Rong; Parisi, Jürgen

    2015-01-01

    The epitaxial growth of the methoxy functionalized para-quaterphenylene (MOP4) on the (001) faces of the alkali halides NaCl and KCl and on glass is investigated by a combination of lowenergy electron diffraction (LEED), polarized light microscopy (PLM), atomic force microscopy (AFM), and X...

  11. Thorium valency in molten alkali halides in equilibrium with metallic thorium

    International Nuclear Information System (INIS)

    Smirnov, M.V.; Kudyakov, V.Ya.

    1983-01-01

    Metallic thorium is shown to corrode in molten alkali halides even in the absence of external oxidizing agents, alkali cations acting as oxidizing agents. Its corrosion rate grows in the series of alkali chlorides from LiCl to CsCl at constant temperature. Substituting halide anions for one another exerts a smaller influence, the rate rising slightly in going from chlorides to bromides and iodides, having the same alkali cations. Thorium valency is determined coulometrically, the metal being dissolved anodically in molten alkali halides and their mixtures. In fluoride melts it is equal to 4 but in chloride, bromide and iodide ones, as a rule, it has non-integral values between 4 and 2 which diminish as the temperature is raised, as the thorium concentration is lowered, as the radii of alkali cations decrease and those of halide anions increase. The emf of cells Th/N ThHlsub(n) + (1-N) MHl/MHl/C, Hlsub(2(g)) where Hl is Cl, Br or I, M is Li, Na, K, Cs or Na + K, and N < 0.05, is measured as a function of concentration at several temperatures. Expressions are obtained for its concentration dependence. The emf grows in the series of alkali chlorides from LiCl to CsCl, other conditions being equal. (author)

  12. Homocoupling of benzyl halides catalyzed by POCOP-nickel pincer complexes

    KAUST Repository

    Chen, Tao

    2012-08-01

    Two types of POCOP-nickel(II) pincer complexes were prepared by mixing POCOP pincer ligands and NiX 2 in toluene at reflux. The resulting nickel complexes efficiently catalyze the homocoupling reactions of benzyl halides in the presence of zinc. The coupled products were obtained in excellent to quantitative yields. © 2012 Elsevier Ltd. All rights reserved.

  13. Investigation of Photographic Image Quality Estimators

    Science.gov (United States)

    1980-04-01

    Bibeman (1973) describes acutance as being "expressed in terms of the mean square of the gradient of . . . density (in a photographic image) with...the density difference AD. for each interval from the (smoothed) microdensitometer trace (calibrated in density units). 4. Compute the gradient -77...resolution." Rotacion Effects: The conditions were: Target: Shutter Speed: I- requency: Arplitude: Medium contrast, variable aspect 250 milliseconds

  14. Front Cover Photograph & Interview for FREEYE Magazine

    OpenAIRE

    Murray, Matthew

    2003-01-01

    Matthew Murray Front Cover Photograph & Interview for FREEYE Magazine - Dutch Quarterly For Exceptional International Photography, Holland.\\ud The article focuses on Murray's practice, his personal work, commissioned work, advertising, gallery and exhibition work along with his methodology. Looking at Murray's inspirations and how they feed into his personal projects and how this personal work feeds into shooting above the line advertising campaigns. Murray's work blurs the lines between pers...

  15. Feasibility of using Eastman Kodak type 3400 film for high altitude multispectral photography

    Science.gov (United States)

    Perry, L.

    1972-01-01

    A photographic test flight of the NASA RB-57F was conducted on March 25, 1972, over Houston and West Texas, to determine the suitability of Eastman Kodak type 3400 film as a replacement for type 2402 film in the Hasselblad cameras. An additional purpose was to test GAF film type 2914, a new black and white film similar to 2402, but with higher maximum gamma and greater dynamic range.

  16. Tracking Protests Using Geotagged Flickr Photographs.

    Directory of Open Access Journals (Sweden)

    Merve Alanyali

    Full Text Available Recent years have witnessed waves of protests sweeping across countries and continents, in some cases resulting in political and governmental change. Much media attention has been focused on the increasing usage of social media to coordinate and provide instantly available reports on these protests. Here, we investigate whether it is possible to identify protest outbreaks through quantitative analysis of activity on the photo sharing site Flickr. We analyse 25 million photos uploaded to Flickr in 2013 across 244 countries and regions, and determine for each week in each country and region what proportion of the photographs are tagged with the word "protest" in 34 different languages. We find that higher proportions of "protest"-tagged photographs in a given country and region in a given week correspond to greater numbers of reports of protests in that country and region and week in the newspaper The Guardian. Our findings underline the potential value of photographs uploaded to the Internet as a source of global, cheap and rapidly available measurements of human behaviour in the real world.

  17. Studies and applications of neutron radiography with film methods

    International Nuclear Information System (INIS)

    Ikeda, Yasushi

    1989-01-01

    Neutron radiography has been studied with film methods and applied to some industrial applications. The film methods include not only conventional silver-halide emulsion films, such as industrial, medical or soft X-ray ones, but also track-etch films and those for indirect methods. The characteristics of the film methods are analyzed and investigated with using various image converters, such as gadolinium metal foil and evaporation films, or some scintillation converters such as NE426. The sensitivities and MTFs for various sets of films and converters have been obtained, which gives a chart of the correlation between the appropriate exposure and resolving powers for them. From the chart, one can select some proper sets for the purpose and given conditions of neutron radiography facilities. The film methods have been applied to inspect very fine cracks in thick steel blocks and plates. It is also applied to observe nuclear fuel pellets or irradiated nuclear fuel pins. Furthermore, the film method has been used for neutron computed tomography. Very fine Eu-particles in TiO pellets, which diameters are nearly 300 micron, can be reconstructed by the neutron CT. The fine neutron CT will be useful for the inspection of Pu-particles in mixed oxide nuclear fuel pellets for future advance nuclear reactors. (author)

  18. 2D halide perovskite-based van der Waals heterostructures: contact evaluation and performance modulation

    Science.gov (United States)

    Guo, Yaguang; Saidi, Wissam A.; Wang, Qian

    2017-09-01

    Halide perovskites and van der Waals (vdW) heterostructures are both of current interest owing to their novel properties and potential applications in nano-devices. Here, we show the great potential of 2D halide perovskite sheets (C4H9NH3)2PbX4 (X  =  Cl, Br and I) that were synthesized recently (Dou et al 2015 Science 349 1518-21) as the channel materials contacting with graphene and other 2D metallic sheets to form van der Waals heterostructures for field effect transistor (FET). Based on state-of-the-art theoretical simulations, we show that the intrinsic properties of the 2D halide perovskites are preserved in the heterojunction, which is different from the conventional contact with metal surfaces. The 2D halide perovskites form a p-type Schottky barrier (Φh) contact with graphene, where tunneling barrier exists, and a negative band bending occurs at the lateral interface. We demonstrate that the Schottky barrier can be turned from p-type to n-type by doping graphene with nitrogen atoms, and a low-Φh or an Ohmic contact can be realized by doping graphene with boron atoms or replacing graphene with other high-work-function 2D metallic sheets such as ZT-MoS2, ZT-MoSe2 and H-NbS2. This study not only predicts a 2D halide perovskite-based FETs, but also enhances the understanding of tuning Schottky barrier height in device applications.

  19. Halide peroxidase in tissues that interact with bacteria in the host squid Euprymna scolopes.

    Science.gov (United States)

    Small, A L; McFall-Ngai, M J

    1999-03-15

    An enzyme with similarities to myeloperoxidase, the antimicrobial halide peroxidase in mammalian neutrophils, occurs abundantly in the light organ tissue of Euprymna scolopes, a squid that maintains a beneficial association with the luminous bacterium Vibrio fischeri. Using three independent assays typically applied to the analysis of halide peroxidase enzymes, we directly compared the activity of the squid enzyme with that of human myeloperoxidase. One of these methods, the diethanolamine assay, confirmed that the squid peroxidase requires halide ions for its activity. The identification of a halide peroxidase in a cooperative bacterial association suggested that this type of enzyme can function not only to control pathogens, but also to modulate the interactions of host animals with their beneficial partners. To determine whether the squid peroxidase functions under both circumstances, we examined its distribution in a variety of host tissues, including those that typically interact with bacteria and those that do not. Tissues interacting with bacteria included those that have specific cooperative associations with bacteria (i.e., the light organ and accessory nidamental gland) and those that have transient nonspecific interactions with bacteria (i.e., the gills, which clear the cephalopod circulatory system of invading microorganisms). These bacteria-associated tissues were compared with the eye, digestive gland, white body, and ink-producing tissues, which do not typically interact directly with bacteria. Peroxidase enzyme assays, immunocytochemical localization, and DNA-RNA hybridizations showed that the halide-dependent peroxidase is consistently expressed in high concentration in tissues that interact bacteria. Elevated levels of the peroxidase were also found in the ink-producing tissues, which are known to have enzymatic pathways associated with antimicrobial activity. Taken together, these data suggest that the host uses a common biochemical response to

  20. Evaluation of photographs supporting an FFQ developed for adolescents.

    Science.gov (United States)

    Brito, Alessandra Page; Guimarães, Celso Pereira; Pereira, Rosangela Alves

    2014-01-01

    To evaluate the validity of food photographs used to support the reporting of food intake with an FFQ designed for adolescents from Rio de Janeiro, Brazil. A set of ninety-five food photographs was elaborated. The photographs' evaluation process included the acknowledgement of foods and portions in the pictures. In the identification of foods (ninety-five photographs) and typical portions (twelve photographs), the adolescents were requested to answer a structured questionnaire related to the food photographs. The identification of the portion size of amorphous foods (forty-three photographs) was performed using three different portion sizes of actual preparations. The proportions (and 95% confidence intervals) of adolescents who correctly identified foods and portion size in each photograph were estimated. A public school in Niterói, Rio de Janeiro State, Brazil. Sixty-two adolescents between 11·0 and 18·9 years old, randomly selected. At least 90% of adolescents correctly identified the food in ninety-two photographs and the food in the three remaining photographs was recognized by 80-89% of the adolescents. At least 98% of the adolescents correctly identified eleven typical or natural portions in the food photographs. For amorphous foods, at least 70% of teenagers correctly identified the portion size in the photograph of thirty-one foods; for the other photographs, the portion size was correctly recognized by 50-69% of the adolescents for eight foods and by less than 50% of adolescents for four foods. The analysed photographs are appropriate visual aids to the reporting of food consumption by adolescents.

  1. Possibility of studying the activity of rocks by the observation of. cap alpha. -particle tracks in a photographic emulsion

    Energy Technology Data Exchange (ETDEWEB)

    Curie, I

    1946-01-01

    A detailed discussion is presented on the possibility of determining the uranium and thorium content of ordinary rocks by observing ..cap alpha..-particle tracks in a photographic film applied to the rocks' surface. Such determinations can be made only where radioactive equilibrium can be assumed. For the examination of normal granite, exposures of several months are needed. The same method can be used to study the distribution of radioactive elements within the rock.

  2. Lead Halide Perovskite Photovoltaic as a Model p-i-n Diode.

    Science.gov (United States)

    Miyano, Kenjiro; Tripathi, Neeti; Yanagida, Masatoshi; Shirai, Yasuhiro

    2016-02-16

    The lead halide perovskite photovoltaic cells, especially the iodide compound CH3NH3PbI3 family, exhibited enormous progress in the energy conversion efficiency in the past few years. Although the first attempt to use the perovskite was as a sensitizer in a dye-sensitized solar cell, it has been recognized at the early stage of the development that the working of the perovskite photovoltaics is akin to that of the inorganic thin film solar cells. In fact, theoretically perovskite is always treated as an ordinary direct band gap semiconductor and hence the perovskite photovoltaics as a p-i-n diode. Despite this recognition, research effort along this line of thought is still in pieces and incomplete. Different measurements have been applied to different types of devices (different not only in the materials but also in the cell structures), making it difficult to have a coherent picture. To make the situation worse, the perovskite photovoltaics have been plagued by the irreproducible optoelectronic properties, most notably the sweep direction dependent current-voltage relationship, the hysteresis problem. Under such circumstances, it is naturally very difficult to analyze the data. Therefore, we set out to make hysteresis-free samples and apply time-tested models and numerical tools developed in the field of inorganic semiconductors. A series of electrical measurements have been performed on one type of CH3NH3PbI3 photovoltaic cells, in which a special attention was paid to ensure that their electronic reproducibility was better than the fitting error in the numerical analysis. The data can be quantitatively explained in terms of the established models of inorganic semiconductors: current/voltage relationship can be very well described by a two-diode model, while impedance spectroscopy revealed the presence of a thick intrinsic layer with the help of a numerical solver, SCAPS, developed for thin film solar cell analysis. These results point to that CH3NH3PbI3 is an

  3. X-ray photographs of a solar active region with a multilayer telescope at normal incidence

    Science.gov (United States)

    Underwood, J. H.; Bruner, M. E.; Haisch, B. M.; Brown, W. A.; Acton, L. W.

    1987-01-01

    An astronomical photograph was obtained with a multilayer X-ray telescope. A 4-cm tungsten-carbon multilayer mirror was flown as part of an experimental solar rocket payload, and successful images were taken of the sun at normal incidence at a wavelength of 44 A. Coronal Si XII emission from an active region was recorded on film; as expected, the structure is very similar to that observed at O VIII wavelengths by the Solar Maximum Mission flat-crystal spectrometer at the same time. The small, simple optical system used in this experiment appears to have achieved a resolution of 5 to 10 arcsec.

  4. Development kinetics of silver clusters on silver halides

    International Nuclear Information System (INIS)

    Grzesiak, S.; Belloni, J.; Marignier, J.-L.

    2008-01-01

    Silver nuclei are produced by pulse radiolysis at the surface of AgCl nanocrystallites in the presence of an electron donor, the methyl viologen, which induces the growth of silver nuclei. The experimental results observed on the increase of the silver atom concentration and on the decay of the donor concentration during this process, which is similar to the photographic development by an electron donor, are compared with the kinetics obtained from numerical simulation. The model assumes that the formation of silver clusters with a supercritical nuclearity is required before the start of an electron transfer reaction from the two reduced forms of the donor methyl viologen to the silver clusters. The reaction is controlled by the access of the donor to the surface sites of the AgCl crystallite. The rate constant values of the successive steps of the mechanism are derived from the adjustment of calculated kinetics to experimental signals under various conditions, using a single set of parameters which are fairly suitable under all conditions studied

  5. Studies on radiation-sensitive nonsilver halide materials, (2)

    International Nuclear Information System (INIS)

    Komizu, Hideo; Honda, Koichi; Yabe, Akira; Kawasaki, Masami; Yamanaka, Takeshi.

    1980-01-01

    Dye-precursors made from furfural and some aniline derivatives become red-colored upon irradiation with ionization radiatios in PVC matrix, forming Stenhouse salts with the HCl evolved from the matrix. The coloration of the precursor from N-methylaniline, having the most excellent potential for dosimetry among the precursors, was studied for the irradiation of electron beam (60 kV) and X-ray (50 - 240 kVp). The following conclusions were obtained for the electron beam bombardment. (1) The response range is 10 -8 - 10 -6 C/cm 2 or 10 3 - 10 5 rad, where good linearity between coloration and charge density exists. (2) The highest sensitivity is obtained when the concentration of the precursor is >=5 wt% for the amount of PVC and the film thickness is >=32 μm. (3) Addition of 25 wt% of DOP enhances not only the sensitivity by ca. 20% but also the stability of the color from several days to several months. (4) The sensitivity is increased by ca. 15% when a conductive base is used for the film. (5) G value for the formation of the dye, i.e., that for the formation of HCl is 13.5 - 15.5. The followings were obtained for the irradiation of X-ray. (1) The response range is 10 3 - 10 5 R or rad. (2) The sensitivity for the absorbed dose is independent of the energy but is approximately proportional to the film thickness. (3) The sensitivity is higher than that for electrons by the factor of ca. 1.6, reflecting the higher G(HCl) value, 23 - 25. (author)

  6. Preferences for photographic art among hospitalized patients with cancer.

    Science.gov (United States)

    Hanson, Hazel; Schroeter, Kathryn; Hanson, Andrew; Asmus, Kathryn; Grossman, Azure

    2013-07-01

    To determine the preferences of patients with cancer for viewing photographic art in an inpatient hospital setting and to evaluate the impact of viewing photographic art. Quantitative, exploratory, single-group, post-test descriptive design incorporating qualitative survey questions. An academic medical center in the midwestern United States. 80 men (n = 44) and women (n = 36) aged 19-85 years (X = 49) and hospitalized for cancer treatment. Participants viewed photographs via computers and then completed a five-instrument electronic survey. Fatigue, quality of life, performance status, perceptions of distraction and restoration, and content categories of photographs. Ninety-six percent of participants enjoyed looking at the study photographs. The photographs they preferred most often were lake sunset (76%), rocky river (66%), and autumn waterfall (66%). The most rejected photographs were amusement park (54%), farmer's market vegetable table (51%), and kayakers (49%). The qualitative categories selected were landscape (28%), animals (15%), people (14%), entertainment (10%), imagery (10%), water (7%), spiritual (7%), flowers (6%), and landmark (3%). Some discrepancy between the quantitative and qualitative sections may be related to participants considering water to be a landscape. The hypothesis that patients' preferences for a category of photographic art are affected by the psychophysical and psychological qualities of the photographs, as well as the patients' moods and characteristics, was supported. Nurses can play an active role in helping patients deal with the challenges of long hospital stays and life-threatening diagnoses through distraction and restoration interventions such as viewing photographic images of nature. Nurses can use photographic imagery to provide a restorative intervention during the hospital experience. Photographic art can be used as a distraction from the hospital stay and the uncertainty of a cancer diagnosis. Having patients view

  7. The chemistry of positronium. Part VI: inhibition and enhancement of positronium formation in aqueous solutions of halides, sulfide and thiocyanate

    International Nuclear Information System (INIS)

    Duplatre, G.; Abbe, J.C.; Maddock, A.G.; Haessler, A.

    1977-01-01

    The formation of positronium in aqueous solutions of halides, sulfide and thiocyanate has been investigated. Inhibiting and enhancing reactions of positronium formation are found. The results are discussed in terms of the spur model

  8. Passivation Using Molecular Halides Increases Quantum Dot Solar Cell Performance

    KAUST Repository

    Lan, Xinzheng; Voznyy, Oleksandr; Kiani, Amirreza; Garcí a de Arquer, F. Pelayo; Abbas, Abdullah Saud; Kim, Gi-Hwan; Liu, Mengxia; Yang, Zhenyu; Walters, Grant; Xu, Jixian; Yuan, Mingjian; Ning, Zhijun; Fan, Fengjia; Kanjanaboos, Pongsakorn; Kramer, Illan; Zhitomirsky, David; Lee, Philip; Perelgut, Alexander; Hoogland, Sjoerd; Sargent, Edward H.

    2015-01-01

    © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Here we report a solution-based passivation scheme is developed featuring the use of molecular iodine and PbS colloidal quantum dots (CQDs). The improved passivation translates into a longer carrier diffusion length in the solid film. This allows thicker solar-cell devices to be built while preserving efficient charge collection, leading to a certified power conversion efficiency of 9.9%, which is a new record in CQD solar cells.

  9. Passivation Using Molecular Halides Increases Quantum Dot Solar Cell Performance.

    Science.gov (United States)

    Lan, Xinzheng; Voznyy, Oleksandr; Kiani, Amirreza; García de Arquer, F Pelayo; Abbas, Abdullah Saud; Kim, Gi-Hwan; Liu, Mengxia; Yang, Zhenyu; Walters, Grant; Xu, Jixian; Yuan, Mingjian; Ning, Zhijun; Fan, Fengjia; Kanjanaboos, Pongsakorn; Kramer, Illan; Zhitomirsky, David; Lee, Philip; Perelgut, Alexander; Hoogland, Sjoerd; Sargent, Edward H

    2016-01-13

    A solution-based passivation scheme is developed featuring the use of molecular iodine and PbS colloidal quantum dots (CQDs). The improved passivation translates into a longer carrier diffusion length in the solid film. This allows thicker solar-cell devices to be built while preserving efficient charge collection, leading to a certified power conversion efficiency of 9.9%, which is a new record in CQD solar cells. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Passivation Using Molecular Halides Increases Quantum Dot Solar Cell Performance

    KAUST Repository

    Lan, Xinzheng

    2015-11-18

    © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Here we report a solution-based passivation scheme is developed featuring the use of molecular iodine and PbS colloidal quantum dots (CQDs). The improved passivation translates into a longer carrier diffusion length in the solid film. This allows thicker solar-cell devices to be built while preserving efficient charge collection, leading to a certified power conversion efficiency of 9.9%, which is a new record in CQD solar cells.

  11. Methyl halide fluxes from tropical plants under controlled radiation and temperature regimes

    Science.gov (United States)

    Blei, Emanuel; Yokouchi, Yoko; Saito, Takuya; Nozoe, Susumu

    2015-04-01

    Methyl halides (CH3Cl, CH3Br, CH3I) contribute significantly to the halogen burden of the atmosphere and have the potential to influence the stratospheric ozone layer through their catalytic effect in the Chapman cycle. As such they have been studied over the years, and many plants and biota have been examined for their potential to act as a source of these gases. One of the potentially largest terrestrial sources identified was tropical vegetation such as tropical ferns and Dipterocarp trees. Most of these studies concentrated on the identification and quantification of such fluxes rather than their characteristics and often the chambers used in these studies were either opaque or only partially transparent to the full solar spectrum. Therefore it is not certain to which degree emissions of methyl halides are innate to the plants and how much they might vary due to radiation or temperature conditions inside the enclosures. In a separate development it had been proposed that UV-radiation could cause live plant materials to be become emitters of methane even under non-anoxic conditions. As methane is chemically very similar to methyl halides and had been proposed to be produced from methyl-groups ubiquitously found in plant cell material there is a relatively good chance that such a production mechanism would also apply to methyl halides. To test whether radiation can affect elevated emissions of methyl halides from plant materials and to distinguish this from temperature effects caused by heat build-up in chambers a set of controlled laboratory chamber enclosures under various radiation and temperature regimes was conducted on four different tropical plant species (Magnolia grandiflora, Cinnamonum camphora, Cyathea lepifera, Angiopteris lygodiifolia), the latter two of which had previously been identified as strong methyl halide emitters. Abscised leaf samples of these species were subjected to radiation treatments such UV-B, UV-A and broad spectrum radiation

  12. Vibrational Spectra of Discrete UO22+ Halide Complexes in the Gas Phase

    International Nuclear Information System (INIS)

    Groenewold, G.S.; Van Stipdonk, Michael J.; Oomens, Jos; De Jong, Wibe A.; Gresham, Garold L.; Mcilwain, Michael

    2010-01-01

    The intrinsic binding of halide ions to the metal center in the uranyl molecule is a topic of ongoing research interest in both the actinide separations and theoretical communities. Investigations of structure in the condensed phases is frequently obfuscated by solvent interactions that can alter ligand binding and spectroscopic properties. The approach taken in this study is to move the uranyl halide complexes into the gas phase where they are free from solvent interactions, and then interrogate their vibrational spectroscopy using infrared multiple photon dissociation (IRMPD). The spectra of cationic coordination complexes having the composition (UO 2 (X)(ACO) 3 ) + (where X = F, Cl, Br and I; ACO = acetone) were acquired using electrospray for ion formation, and monitoring the ion signal from the photoelimination of ACO ligands. The studies showed that the asymmetric ν 3 UO 2 frequency was insensitive to halide identity as X was varied from Cl to I, suggesting that in these pseudo-octahedral complexes, changing the nucleophilicity of the halide did not appreciably alter its binding in the complex. The ν 3 peak in the spectrum of the F-containing complex was 9 cm -1 lower indicating stronger coordination in this complex. Similarly the ACO carbonyl stretches showed that the C=O frequency was relatively insensitive to the identity of the halide, although a modest shift to higher wavenumber was seen for the complexes with the more nucleophilic anions, consistent with the idea that they loosen solvent binding. Surprisingly, the ν 1 stretch was activated when the softer anions Cl, Br and I were present in the complexes. IR studies of the anionic complexes (UO 2 X 3 ) - (where X = Cl - , Br - and I - ) compared the ν 3 UO 2 modes versus halide, and showed that the ν 3 values decreased with increasing anion nucleophilicity. This observation was consistent with DFT calculations that indicated that (UO 2 X 2 ) - -X, and (UO 2 X 2 )·-X - dissociation energies

  13. Conformational isomerism in mixed-ligand complexes of 2,2'-bipyridine and triphenylphosphine with copper(I) halides

    International Nuclear Information System (INIS)

    Barron, P.F.; Engelhardt, L.M.; Healy, P.C.; Kildea, J.D.; White, A.H.

    1988-01-01

    Mixed-ligand complexes of triphenylphosphine and 2,2'-bipyridine and copper(I) halides have been synthesized. The 31 P NMR spectra of the complexes were measured and are reported along with data for complete structural characterization of the complexes. The results indicate a novel dichotomy of conformational isomers to be present in the chloride lattice. The Cu-P bond length was found to not vary with different halides. 8 refs., 4 figs., 6 tabs

  14. Adobe Photoshop CS6 for photographers

    CERN Document Server

    Evening, Martin

    2012-01-01

    Renowned Photographer and Photoshop hall-of-famer, Martin Evening returns with his comprehensive guide to Photoshop. This acclaimed work covers everything from the core aspects of working in Photoshop to advanced techniques for refined workflows and professional results. Using concise advice, clear instruction and real world examples, this essential guide will give you the skills, regardless of your experience, to create professional quality results. A robust accompanying website features sample images, tutorial videos, bonus chapters and a plethora of extra resources. Quite simply, this is

  15. iPad for digital photographers

    CERN Document Server

    Story, Derrick

    2013-01-01

    Discover innovative ways to strengthen your photography business with your iPad Many photographers are turning to the flexible, easy-to-use tools of the iPad and relying on them to wear a variety of hats in their photography business. Whether portable portfolio, editing tool, payment-tracking system, or appointment calendar, the iPad melds together the best attributes of the cell phone and a laptop computer and this unique book highlights them all. With this helpful resource, you'll learn how to get the most out of your iPad to not only improve your business but also enhance your p

  16. Adobe Photoshop CS5 for photographers

    CERN Document Server

    Evening, Martin

    2010-01-01

    With the new edition of this proven bestseller, Photoshop users can master the power of Photoshop CS5 with internationally renowned photographer and Photoshop hall-of-famer Martin Evening by their side.  In this acclaimed reference work, Martin covers everything from the core aspects of working in Photoshop to advanced techniques for professional results. Subjects covered include organizing a digital workflow, improving creativity, output, automating Photoshop, and using Camera RAW. The style of the book is extremely clear, with real examples, diagrams, illustrations, and step-by-step ex

  17. Adobe Photoshop Elements 11 for photographers

    CERN Document Server

    Andrews, Philip

    2013-01-01

    To coincide with some of the biggest changes in Photoshop Elements for years, Philip Andrews completely revises his bestselling title to include all the new features of this release. See how the new interface works alongside new tools, techniques and workflows to make editing, enhancing and sharing your pictures easier than ever. And as always, he introduces the changed and improved features with colorful illustrations and the clear step-by-step instruction that has made his books the go-to titles for photographers the world over. ????In this edition Andrews highlights followi

  18. Adsorption of molecular additive onto lead halide perovskite surfaces: A computational study on Lewis base thiophene additive passivation

    Science.gov (United States)

    Zhang, Lei; Yu, Fengxi; Chen, Lihong; Li, Jingfa

    2018-06-01

    Organic additives, such as the Lewis base thiophene, have been successfully applied to passivate halide perovskite surfaces, improving the stability and properties of perovskite devices based on CH3NH3PbI3. Yet, the detailed nanostructure of the perovskite surface passivated by additives and the mechanisms of such passivation are not well understood. This study presents a nanoscopic view on the interfacial structure of an additive/perovskite interface, consisting of a Lewis base thiophene molecular additive and a lead halide perovskite surface substrate, providing insights on the mechanisms that molecular additives can passivate the halide perovskite surfaces and enhance the perovskite-based device performance. Molecular dynamics study on the interactions between water molecules and the perovskite surfaces passivated by the investigated additive reveal the effectiveness of employing the molecular additives to improve the stability of the halide perovskite materials. The additive/perovskite surface system is further probed via molecular engineering the perovskite surfaces. This study reveals the nanoscopic structure-property relationships of the halide perovskite surface passivated by molecular additives, which helps the fundamental understanding of the surface/interface engineering strategies for the development of halide perovskite based devices.

  19. Sensitivity of UF-R, UF-VCh, UF-VR films used for soft x-ray (lambda=2+10A) detection

    International Nuclear Information System (INIS)

    Aglitskij, E.V.; Bojko, V.A.; Kalinkina, T.A.

    1975-01-01

    The sensitometric characteristics of the following types of photographic film were measured in the range of wavelengths 2-10A: UF-R, UF-VCh, and UF-VR. It was demonstrated that UF-VR photographic film is four times as sensitive as UF-R film and 1.6 times as sensitive as UF-VCh film; it is also most suitable film for x-ray spectroscopy of multiply charged ions and for diagnosing high-temperature laser plasma

  20. Preserving and Archiving Astronomical Photographic Plates

    Science.gov (United States)

    Castelaz, M. W.; Cline, J. D.

    2005-05-01

    Astronomical objects change with time. New observations complement past observations recorded on photographic plates. Analyses of changes provide essential routes to information about an object's formation, constitution and evolution. Preserving a century of photographic plate observations is thus of paramount importance. Plate collections are presently widely dispersed; plates may be stored in poor conditions, and are effectively inaccessible to both researchers and historians. We describe a planned project at Pisgah Astronomical Research Institute to preserve the collections of astronomical plates in the United States by gathering them into a single storage location. Collections will be sorted, cleaned, and cataloged on-line so as to provide access to researchers. Full scientific and historic use of the material then requires the observations themselves to be accessible digitally. The project's goal will be the availability of these data as a unique, fully-maintained scientific and educational resource. The new archive will support trans-disciplinary research such as the chemistry of the Earth's atmosphere, library information science, trends in local weather patterns, and impacts of urbanization on telescope use, while the hand-written observatory logs will be a valuable resource for science historians and biographers.