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Sample records for photon emission microscope

  1. Microscopic theory of cavity-enhanced single-photon emission from optical two-photon Raman processes

    Science.gov (United States)

    Breddermann, Dominik; Praschan, Tom; Heinze, Dirk; Binder, Rolf; Schumacher, Stefan

    2018-03-01

    We consider cavity-enhanced single-photon generation from stimulated two-photon Raman processes in three-level systems. We compare four fundamental system configurations, one Λ -, one V-, and two ladder (Ξ -) configurations. These can be realized as subsystems of a single quantum dot or of quantum-dot molecules. For a new microscopic understanding of the Raman process, we analyze the Heisenberg equation of motion applying the cluster-expansion scheme. Within this formalism an exact and rigorous definition of a cavity-enhanced Raman photon via its corresponding Raman correlation is possible. This definition for example enables us to systematically investigate the on-demand potential of Raman-transition-based single-photon sources. The four system arrangements can be divided into two subclasses, Λ -type and V-type, which exhibit strongly different Raman-emission characteristics and Raman-emission probabilities. Moreover, our approach reveals whether the Raman path generates a single photon or just induces destructive quantum interference with other excitation paths. Based on our findings and as a first application, we gain a more detailed understanding of experimental data from the literature. Our analysis and results are also transferable to the case of atomic three-level-resonator systems and can be extended to more complicated multilevel schemes.

  2. Radiation emission as a virtually exact realization of Heisenbergs microscope

    Energy Technology Data Exchange (ETDEWEB)

    Andersen, K.K., E-mail: kka@phys.au.dk [Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, 8000 Aarhus C (Denmark); Brock, S. [Department of Culture and Society, Aarhus University, Jens Chr. Skous Vej 5, 8000 Aarhus C (Denmark); Esberg, J.; Thomsen, H.D.; Uggerhøj, U.I. [Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, 8000 Aarhus C (Denmark)

    2013-11-15

    Through the concept of ‘formation length’, recently observed directly in the radiation emission from ultrarelativistic electrons and an essential component in the interpretation of strong field radiation from electrons penetrating single crystals, we discuss the indeterminacy in the location of radiation emission. The analogy with the indeterminacy in the Heisenberg microscope Gedanken experiment is demonstrated from a number of viewpoints to be almost exact. The positive attitude regarding photon emission as a process that is somehow located in space and time is emphasized. We therefore interpret the measurements of formation lengths in radiation emission as a practically realizable version – using virtual incident photons instead of real – of the Heisenberg microscope Gedanken experiment.

  3. Photon scanning tunneling microscope in combination with a force microscope

    NARCIS (Netherlands)

    Moers, M.H.P.; Moers, M.H.P.; Tack, R.G.; van Hulst, N.F.; Bölger, B.; Bölger, B.

    1994-01-01

    The simultaneous operation of a photon scanning tunneling microscope with an atomic force microscope is presented. The use of standard atomic force silicon nitride cantilevers as near-field optical probes offers the possibility to combine the two methods. Vertical forces and torsion are detected

  4. Compact scanning transmission x-ray microscope at the photon factory

    International Nuclear Information System (INIS)

    Takeichi, Yasuo; Inami, Nobuhito; Ono, Kanta; Suga, Hiroki; Takahashi, Yoshio

    2016-01-01

    We report the design and performance of a compact scanning transmission X-ray microscope developed at the Photon Factory. Piezo-driven linear stages are used as coarse stages of the microscope to realize excellent compactness, mobility, and vibrational and thermal stability. An X-ray beam with an intensity of ∼10 7 photons/s was focused to a diameter of ∼40 nm at the sample. At the soft X-ray undulator beamline used with the microscope, a wide range of photon energies (250–1600 eV) is available. The microscope has been used to research energy materials and in environmental sciences

  5. Performance assessment of the single photon emission microscope: high spatial resolution SPECT imaging of small animal organs

    International Nuclear Information System (INIS)

    Mejia, J.; Reis, M.A.; Miranda, A.C.C.; Batista, I.R.; Barboza, M.R.F.; Shih, M.C.; Fu, G.; Chen, C.T.; Meng, L.J.; Bressan, R.A.; Amaro, E. Jr

    2013-01-01

    The single photon emission microscope (SPEM) is an instrument developed to obtain high spatial resolution single photon emission computed tomography (SPECT) images of small structures inside the mouse brain. SPEM consists of two independent imaging devices, which combine a multipinhole collimator, a high-resolution, thallium-doped cesium iodide [CsI(Tl)] columnar scintillator, a demagnifying/intensifier tube, and an electron-multiplying charge-coupling device (CCD). Collimators have 300- and 450-µm diameter pinholes on tungsten slabs, in hexagonal arrays of 19 and 7 holes. Projection data are acquired in a photon-counting strategy, where CCD frames are stored at 50 frames per second, with a radius of rotation of 35 mm and magnification factor of one. The image reconstruction software tool is based on the maximum likelihood algorithm. Our aim was to evaluate the spatial resolution and sensitivity attainable with the seven-pinhole imaging device, together with the linearity for quantification on the tomographic images, and to test the instrument in obtaining tomographic images of different mouse organs. A spatial resolution better than 500 µm and a sensitivity of 21.6 counts·s -1 ·MBq -1 were reached, as well as a correlation coefficient between activity and intensity better than 0.99, when imaging 99m Tc sources. Images of the thyroid, heart, lungs, and bones of mice were registered using 99m Tc-labeled radiopharmaceuticals in times appropriate for routine preclinical experimentation of <1 h per projection data set. Detailed experimental protocols and images of the aforementioned organs are shown. We plan to extend the instrument's field of view to fix larger animals and to combine data from both detectors to reduce the acquisition time or applied activity

  6. Performance assessment of the single photon emission microscope: high spatial resolution SPECT imaging of small animal organs

    Energy Technology Data Exchange (ETDEWEB)

    Mejia, J. [Hospital Israelita Albert Einstein, Instituto do Cérebro, São Paulo, SP (Brazil); Reis, M.A. [Hospital Israelita Albert Einstein, Instituto do Cérebro, São Paulo, SP (Brazil); Laboratório Interdisciplinar de Neurociências Clínicas, Departamento de Psiquiatria, Universidade Federal de São Paulo, São Paulo, SP (Brazil); Miranda, A.C.C. [Hospital Israelita Albert Einstein, Instituto do Cérebro, São Paulo, SP (Brazil); Batista, I.R. [Hospital Israelita Albert Einstein, Instituto do Cérebro, São Paulo, SP (Brazil); Laboratório Interdisciplinar de Neurociências Clínicas, Departamento de Psiquiatria, Universidade Federal de São Paulo, São Paulo, SP (Brazil); Barboza, M.R.F.; Shih, M.C. [Hospital Israelita Albert Einstein, Instituto do Cérebro, São Paulo, SP (Brazil); Fu, G. [GE Global Research, Schenectady, NY (United States); Chen, C.T. [Department of Radiology, University of Chicago, Chicago, IL (United States); Meng, L.J. [Department of Nuclear, Plasma and Radiological Engineering, University of Illinois, Urbana-Champaign, IL (United States); Bressan, R.A. [Hospital Israelita Albert Einstein, Instituto do Cérebro, São Paulo, SP (Brazil); Laboratório Interdisciplinar de Neurociências Clínicas, Departamento de Psiquiatria, Universidade Federal de São Paulo, São Paulo, SP (Brazil); Amaro, E. Jr [Hospital Israelita Albert Einstein, Instituto do Cérebro, São Paulo, SP (Brazil)

    2013-11-06

    The single photon emission microscope (SPEM) is an instrument developed to obtain high spatial resolution single photon emission computed tomography (SPECT) images of small structures inside the mouse brain. SPEM consists of two independent imaging devices, which combine a multipinhole collimator, a high-resolution, thallium-doped cesium iodide [CsI(Tl)] columnar scintillator, a demagnifying/intensifier tube, and an electron-multiplying charge-coupling device (CCD). Collimators have 300- and 450-µm diameter pinholes on tungsten slabs, in hexagonal arrays of 19 and 7 holes. Projection data are acquired in a photon-counting strategy, where CCD frames are stored at 50 frames per second, with a radius of rotation of 35 mm and magnification factor of one. The image reconstruction software tool is based on the maximum likelihood algorithm. Our aim was to evaluate the spatial resolution and sensitivity attainable with the seven-pinhole imaging device, together with the linearity for quantification on the tomographic images, and to test the instrument in obtaining tomographic images of different mouse organs. A spatial resolution better than 500 µm and a sensitivity of 21.6 counts·s{sup -1}·MBq{sup -1} were reached, as well as a correlation coefficient between activity and intensity better than 0.99, when imaging {sup 99m}Tc sources. Images of the thyroid, heart, lungs, and bones of mice were registered using {sup 99m}Tc-labeled radiopharmaceuticals in times appropriate for routine preclinical experimentation of <1 h per projection data set. Detailed experimental protocols and images of the aforementioned organs are shown. We plan to extend the instrument's field of view to fix larger animals and to combine data from both detectors to reduce the acquisition time or applied activity.

  7. Performance assessment of the single photon emission microscope: high spatial resolution SPECT imaging of small animal organs

    Directory of Open Access Journals (Sweden)

    J. Mejia

    2013-11-01

    Full Text Available The single photon emission microscope (SPEM is an instrument developed to obtain high spatial resolution single photon emission computed tomography (SPECT images of small structures inside the mouse brain. SPEM consists of two independent imaging devices, which combine a multipinhole collimator, a high-resolution, thallium-doped cesium iodide [CsI(Tl] columnar scintillator, a demagnifying/intensifier tube, and an electron-multiplying charge-coupling device (CCD. Collimators have 300- and 450-µm diameter pinholes on tungsten slabs, in hexagonal arrays of 19 and 7 holes. Projection data are acquired in a photon-counting strategy, where CCD frames are stored at 50 frames per second, with a radius of rotation of 35 mm and magnification factor of one. The image reconstruction software tool is based on the maximum likelihood algorithm. Our aim was to evaluate the spatial resolution and sensitivity attainable with the seven-pinhole imaging device, together with the linearity for quantification on the tomographic images, and to test the instrument in obtaining tomographic images of different mouse organs. A spatial resolution better than 500 µm and a sensitivity of 21.6 counts·s-1·MBq-1 were reached, as well as a correlation coefficient between activity and intensity better than 0.99, when imaging 99mTc sources. Images of the thyroid, heart, lungs, and bones of mice were registered using 99mTc-labeled radiopharmaceuticals in times appropriate for routine preclinical experimentation of <1 h per projection data set. Detailed experimental protocols and images of the aforementioned organs are shown. We plan to extend the instrument's field of view to fix larger animals and to combine data from both detectors to reduce the acquisition time or applied activity.

  8. Two-Photon Fluorescence Microscope for Microgravity Research

    Science.gov (United States)

    Fischer, David G.; Zimmerli, Gregory A.; Asipauskas, Marius

    2005-01-01

    A two-photon fluorescence microscope has been developed for the study of biophysical phenomena. Two-photon microscopy is a novel form of laser-based scanning microscopy that enables three-dimensional imaging without many of the problems inherent in confocal microscopy. Unlike one-photon optical microscopy, two-photon microscopy utilizes the simultaneous nonlinear absorption of two near-infrared photons. However, the efficiency of two-photon absorption is much lower than that of one-photon absorption, so an ultra-fast pulsed laser source is typically employed. On the other hand, the critical energy threshold for two-photon absorption leads to fluorophore excitation that is intrinsically localized to the focal volume. Consequently, two-photon microscopy enables optical sectioning and confocal performance without the need for a signal-limiting pinhole. In addition, there is a reduction (relative to one-photon optical microscopy) in photon-induced damage because of the longer excitation wavelength. This reduction is especially advantageous for in vivo studies. Relative to confocal microscopy, there is also a reduction in background fluorescence, and, because of a reduction in Rayleigh scattering, there is a 4 increase of penetration depth. The prohibitive cost of a commercial two-photon fluorescence-microscope system, as well as a need for modularity, has led to the construction of a custom-built system (see Figure 1). This system includes a coherent mode-locked titanium: sapphire laser emitting 120-fs-duration pulses at a repetition rate of 80 MHz. The pulsed laser has an average output power of 800 mW and a wavelength tuning range of 700 to 980 nm, enabling the excitation of a variety of targeted fluorophores. The output from the laser is attenuated, spatially filtered, and then directed into a confocal scanning head that has been modified to provide for side entry of the laser beam. The laser output coupler has been replaced with a dichroic filter that reflects the

  9. Single photon emission tomography

    International Nuclear Information System (INIS)

    Buvat, Irene

    2011-09-01

    The objective of this lecture is to present the single photon emission computed tomography (SPECT) imaging technique. Content: 1 - Introduction: anatomic, functional and molecular imaging; Principle and role of functional or molecular imaging; 2 - Radiotracers: chemical and physical constraints, main emitters, radioisotopes production, emitters type and imaging techniques; 3 - Single photon emission computed tomography: gamma cameras and their components, gamma camera specifications, planar single photon imaging characteristics, gamma camera and tomography; 4 - Quantification in single photon emission tomography: attenuation, scattering, un-stationary spatial resolution, partial volume effect, movements, others; 5 - Synthesis and conclusion

  10. An integrated single- and two-photon non-diffracting light-sheet microscope

    Science.gov (United States)

    Lau, Sze Cheung; Chiu, Hoi Chun; Zhao, Luwei; Zhao, Teng; Loy, M. M. T.; Du, Shengwang

    2018-04-01

    We describe a fluorescence optical microscope with both single-photon and two-photon non-diffracting light-sheet excitations for large volume imaging. With a special design to accommodate two different wavelength ranges (visible: 400-700 nm and near infrared: 800-1200 nm), we combine the line-Bessel sheet (LBS, for single-photon excitation) and the scanning Bessel beam (SBB, for two-photon excitation) light sheet together in a single microscope setup. For a transparent thin sample where the scattering can be ignored, the LBS single-photon excitation is the optimal imaging solution. When the light scattering becomes significant for a deep-cell or deep-tissue imaging, we use SBB light-sheet two-photon excitation with a longer wavelength. We achieved nearly identical lateral/axial resolution of about 350/270 nm for both imagings. This integrated light-sheet microscope may have a wide application for live-cell and live-tissue three-dimensional high-speed imaging.

  11. Microscopic dynamical Casimir effect

    Science.gov (United States)

    Souza, Reinaldo de Melo e.; Impens, François; Neto, Paulo A. Maia

    2018-03-01

    We consider an atom in its ground state undergoing a nonrelativistic oscillation in free space. The interaction with the electromagnetic quantum vacuum leads to two effects to leading order in perturbation theory. When the mechanical frequency is larger than the atomic transition frequency, the dominant effect is the motion-induced transition to an excited state with the emission of a photon carrying the excess energy. We compute the angular distribution of emitted photons and the excitation rate. On the other hand, when the mechanical frequency is smaller than the transition frequency, the leading-order effect is the parametric emission of photon pairs, which constitutes the microscopic counterpart of the dynamical Casimir effect. We discuss the properties of the microscopic dynamical Casimir effect and build a connection with the photon production by an oscillating macroscopic metallic mirror.

  12. Microscopic theory of photon-correlation spectroscopy in strong-coupling semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Schneebeli, Lukas

    2009-11-27

    would be a great contribution in the growing field of quantum optics in semiconductors. The efforts in QD systems are again driven by the atomic systems which not only have shown the vacuum Rabi splitting, but also the second rung, e.g. via direct spectroscopy and via photon-correlation measurements. In this thesis, it is shown that spectrally resolved photon-statistics measurements of the resonance fluorescence from realistic semiconductor quantum-dot systems allow for high contrast identification of the two-photon strong-coupling states. Using a microscopic theory, the second-rung resonance of Jaynes-Cummings ladder is analyzed and optimum excitation conditions are determined. The computed photon-statistics spectrum displays gigantic, experimentally robust resonances at the energetic positions of the second-rung emission. The resonance fluorescence equations are derived and solved for strong-coupling semiconductor quantum-dot systems using a fully quantized multimode theory and a cluster-expansion approach. A reduced model is developed to explain the origin of auto- and cross-correlation resonances in the two-photon emission spectrum of the fluorescent light. These resonances are traced back to the two-photon strong-coupling states of Jaynes-Cummings ladder. The accuracy of the reduced model is verified via numerical solution of the resonance fluorescence equations. The analysis reveals the direct relation between the squeezed-light emission and the strong-coupling states in optically excited semiconductor systems. (orig.)

  13. Photon emission spectroscopy of NiAl(110) in the scanning tunneling microscope

    International Nuclear Information System (INIS)

    Nilius, N.; Ernst, N.; Freund, H.-J.; Johansson, P.

    2000-01-01

    Spectroscopic measurements have been carried out of the light emitted from the NiAl(110)/W tunnel junction of a scanning tunneling microscope. The data reveal two prominent emission lines in the visible and near-infrared region. Corresponding model calculations assign the observed light emission to the radiating decay of the tip-induced plasmon excited in the tip-sample cavity. In agreement with the theory, a low- and a high-energy mode of the plasmon can be distinguished in the experimental data. Since the excitation probability of the two modes is determined by the size of the tunnel cavity, it can be influenced by the radius of the tunnel tip. A blunted tip favors the observation conditions of the higher mode

  14. An ultrafast electron microscope gun driven by two-photon photoemission from a nanotip cathode

    International Nuclear Information System (INIS)

    Bormann, Reiner; Strauch, Stefanie; Schäfer, Sascha; Ropers, Claus

    2015-01-01

    We experimentally and numerically investigate the performance of an advanced ultrafast electron source, based on two-photon photoemission from a tungsten needle cathode incorporated in an electron microscope gun geometry. Emission properties are characterized as a function of the electrostatic gun settings, and operating conditions leading to laser-triggered electron beams of very low emittance (below 20 nm mrad) are identified. The results highlight the excellent suitability of optically driven nano-cathodes for the further development of ultrafast transmission electron microscopy

  15. High-performance imaging of stem cells using single-photon emissions

    Science.gov (United States)

    Wagenaar, Douglas J.; Moats, Rex A.; Hartsough, Neal E.; Meier, Dirk; Hugg, James W.; Yang, Tang; Gazit, Dan; Pelled, Gadi; Patt, Bradley E.

    2011-10-01

    Radiolabeled cells have been imaged for decades in the field of autoradiography. Recent advances in detector and microelectronics technologies have enabled the new field of "digital autoradiography" which remains limited to ex vivo specimens of thin tissue slices. The 3D field-of-view (FOV) of single cell imaging can be extended to millimeters if the low energy (10-30 keV) photon emissions of radionuclides are used for single-photon nuclear imaging. This new microscope uses a coded aperture foil made of highly attenuating elements such as gold or platinum to form the image as a kind of "lens". The detectors used for single-photon emission microscopy are typically silicon detectors with a pixel pitch less than 60 μm. The goal of this work is to image radiolabeled mesenchymal stem cells in vivo in an animal model of tendon repair processes. Single-photon nuclear imaging is an attractive modality for translational medicine since the labeled cells can be imaged simultaneously with the reparative processes by using the dual-isotope imaging technique. The details our microscope's two-layer gold aperture and the operation of the energy-dispersive, pixellated silicon detector are presented along with the first demonstration of energy discrimination with a 57Co source. Cell labeling techniques have been augmented by genetic engineering with the sodium-iodide symporter, a type of reporter gene imaging method that enables in vivo uptake of free 99mTc or an iodine isotope at a time point days or weeks after the insertion of the genetically modified stem cells into the animal model. This microscopy work in animal research may expand to the imaging of reporter-enabled stem cells simultaneously with the expected biological repair process in human clinical trials of stem cell therapies.

  16. Electron and photon emissions from gold nanoparticles irradiated by X-ray photons

    Energy Technology Data Exchange (ETDEWEB)

    Casta, R., E-mail: castaromain@gmail.com, E-mail: romain.casta@irsamc.ups-tlse.fr; Champeaux, J.-P.; Moretto-Capelle, P.; Sence, M.; Cafarelli, P. [Université de Toulouse, UPS, Laboratoire Collisions Agrégats Réactivité, IRSAMC, CNRS, UMR 5589 (France)

    2015-01-15

    In this paper, we develop a totally new probabilistic model for the electron and photon emission of gold nanoparticles irradiated by X-ray photons. This model allows direct applications to recent researches about the radiotherapy enhancement by gold nanoparticles in the context of cancer treatment. Our model uses, in a complete original way, simulated Auger cascade and stopping power to compute electron emission spectra, photon emission spectra and released energy inside the material of gold nanoparticles. It allows us to present new results about the electron and photon emission of gold nanoparticle irradiated by hard X-rays.

  17. Deep two-photon microscopic imaging through brain tissue using the second singlet state from fluorescent agent chlorophyll α in spinach leaf.

    Science.gov (United States)

    Shi, Lingyan; Rodríguez-Contreras, Adrián; Budansky, Yury; Pu, Yang; Nguyen, Thien An; Alfano, Robert R

    2014-06-01

    Two-photon (2P) excitation of the second singlet (S₂) state was studied to achieve deep optical microscopic imaging in brain tissue when both the excitation (800 nm) and emission (685 nm) wavelengths lie in the "tissue optical window" (650 to 950 nm). S₂ state technique was used to investigate chlorophyll α (Chl α) fluorescence inside a spinach leaf under a thick layer of freshly sliced rat brain tissue in combination with 2P microscopic imaging. Strong emission at the peak wavelength of 685 nm under the 2P S₂ state of Chl α enabled the imaging depth up to 450 μm through rat brain tissue.

  18. Microscopic theory of multiple-phonon-mediated dephasing and relaxation of quantum dots near a photonic band gap

    Science.gov (United States)

    Roy, Chiranjeeb; John, Sajeev

    2010-02-01

    We derive a quantum theory of the role of acoustic and optical phonons in modifying the optical absorption line shape, polarization dynamics, and population dynamics of a two-level atom (quantum dot) in the “colored” electromagnetic vacuum of a photonic band-gap (PBG) material. This is based on a microscopic Hamiltonian describing both radiative and vibrational processes quantum mechanically. We elucidate the extent to which phonon-assisted decay limits the lifetime of a single photon-atom bound state and derive the modified spontaneous emission dynamics due to coupling to various phonon baths. We demonstrate that coherent interaction with undamped phonons can lead to an enhanced lifetime of a photon-atom bound state in a PBG. This results in reduction of the steady-state atomic polarization but an increase in the fractionalized upper state population in the photon-atom bound state. We demonstrate, on the other hand, that the lifetime of the photon-atom bound state in a PBG is limited by the lifetime of phonons due to lattice anharmonicities (breakup of phonons into lower energy phonons) and purely nonradiative decay. We also derive the modified polarization decay and dephasing rates in the presence of such damping. This leads to a microscopic, quantum theory of the optical absorption line shapes. Our model and formalism provide a starting point for describing dephasing and relaxation in the presence of external coherent fields and multiple quantum dot interactions in electromagnetic reservoirs with radiative memory effects.

  19. Microscopic theory of multiple-phonon-mediated dephasing and relaxation of quantum dots near a photonic band gap

    International Nuclear Information System (INIS)

    Roy, Chiranjeeb; John, Sajeev

    2010-01-01

    We derive a quantum theory of the role of acoustic and optical phonons in modifying the optical absorption line shape, polarization dynamics, and population dynamics of a two-level atom (quantum dot) in the ''colored'' electromagnetic vacuum of a photonic band-gap (PBG) material. This is based on a microscopic Hamiltonian describing both radiative and vibrational processes quantum mechanically. We elucidate the extent to which phonon-assisted decay limits the lifetime of a single photon-atom bound state and derive the modified spontaneous emission dynamics due to coupling to various phonon baths. We demonstrate that coherent interaction with undamped phonons can lead to an enhanced lifetime of a photon-atom bound state in a PBG. This results in reduction of the steady-state atomic polarization but an increase in the fractionalized upper state population in the photon-atom bound state. We demonstrate, on the other hand, that the lifetime of the photon-atom bound state in a PBG is limited by the lifetime of phonons due to lattice anharmonicities (breakup of phonons into lower energy phonons) and purely nonradiative decay. We also derive the modified polarization decay and dephasing rates in the presence of such damping. This leads to a microscopic, quantum theory of the optical absorption line shapes. Our model and formalism provide a starting point for describing dephasing and relaxation in the presence of external coherent fields and multiple quantum dot interactions in electromagnetic reservoirs with radiative memory effects.

  20. Enhanced two-photon emission from a dressed biexciton

    International Nuclear Information System (INIS)

    Sánchez Muñoz, Carlos; Laussy, Fabrice P; Tejedor, Carlos; Valle, Elena del

    2015-01-01

    Radiative two-photon cascades from biexcitons in semiconductor quantum dots under resonant two-photon excitation are promising candidates for the generation of photon pairs. In this work, we propose a scheme to obtain two-photon emission that allows us to operate under very intense driving fields. This approach relies on the Purcell enhancement of two-photon virtual transitions between states of the biexciton dressed by the laser. The richness provided by the biexcitonic level structure allows to reach a variety of regimes, from antibunched and bunched photon pairs with polarization orthogonal to the driving field, to polarization entangled two-photon emission. This provides evidence that the general paradigm of two-photon emission from a ladder of dressed states can find interesting, particular implementations in a variety of systems. (paper)

  1. Photon emission from massive projectile impacts on solids.

    Science.gov (United States)

    Fernandez-Lima, F A; Pinnick, V T; Della-Negra, S; Schweikert, E A

    2011-01-01

    First evidence of photon emission from individual impacts of massive gold projectiles on solids for a number of projectile-target combinations is reported. Photon emission from individual impacts of massive Au(n) (+q) (1 ≤ n ≤ 400; q = 1-4) projectiles with impact energies in the range of 28-136 keV occurs in less than 10 ns after the projectile impact. Experimental observations show an increase in the photon yield from individual impacts with the projectile size and velocity. Concurrently with the photon emission, electron emission from the impact area has been observed below the kinetic emission threshold and under unlikely conditions for potential electron emission. We interpret the puzzling electron emission and correlated luminescence observation as evidence of the electronic excitation resulting from the high-energy density deposited by massive cluster projectiles during the impact.

  2. Visible-to-visible four-photon ultrahigh resolution microscopic imaging with 730-nm diode laser excited nanocrystals.

    Science.gov (United States)

    Wang, Baoju; Zhan, Qiuqiang; Zhao, Yuxiang; Wu, Ruitao; Liu, Jing; He, Sailing

    2016-01-25

    Further development of multiphoton microscopic imaging is confronted with a number of limitations, including high-cost, high complexity and relatively low spatial resolution due to the long excitation wavelength. To overcome these problems, for the first time, we propose visible-to-visible four-photon ultrahigh resolution microscopic imaging by using a common cost-effective 730-nm laser diode to excite the prepared Nd(3+)-sensitized upconversion nanoparticles (Nd(3+)-UCNPs). An ordinary multiphoton scanning microscope system was built using a visible CW diode laser and the lateral imaging resolution as high as 161-nm was achieved via the four-photon upconversion process. The demonstrated large saturation excitation power for Nd(3+)-UCNPs would be more practical and facilitate the four-photon imaging in the application. A sample with fine structure was imaged to demonstrate the advantages of visible-to-visible four-photon ultrahigh resolution microscopic imaging with 730-nm diode laser excited nanocrystals. Combining the uniqueness of UCNPs, the proposed visible-to-visible four-photon imaging would be highly promising and attractive in the field of multiphoton imaging.

  3. Designing a large field-of-view two-photon microscope using optical invariant analysis.

    Science.gov (United States)

    Bumstead, Jonathan R; Park, Jasmine J; Rosen, Isaac A; Kraft, Andrew W; Wright, Patrick W; Reisman, Matthew D; Côté, Daniel C; Culver, Joseph P

    2018-04-01

    Conventional two-photon microscopy (TPM) is capable of imaging neural dynamics with subcellular resolution, but it is limited to a field-of-view (FOV) diameter [Formula: see text]. Although there has been recent progress in extending the FOV in TPM, a principled design approach for developing large FOV TPM (LF-TPM) with off-the-shelf components has yet to be established. Therefore, we present a design strategy that depends on analyzing the optical invariant of commercially available objectives, relay lenses, mirror scanners, and emission collection systems in isolation. Components are then selected to maximize the space-bandwidth product of the integrated microscope. In comparison with other LF-TPM systems, our strategy simplifies the sequence of design decisions and is applicable to extending the FOV in any microscope with an optical relay. The microscope we constructed with this design approach can image [Formula: see text] lateral and [Formula: see text] axial resolution over a 7-mm diameter FOV, which is a 100-fold increase in FOV compared with conventional TPM. As a demonstration of the potential that LF-TPM has on understanding the microarchitecture of the mouse brain across interhemispheric regions, we performed in vivo imaging of both the cerebral vasculature and microglia cell bodies over the mouse cortex.

  4. Controlling spontaneous emission of light by photonic crystals

    DEFF Research Database (Denmark)

    Lodahl, Peter

    2005-01-01

    Photonic bandgap crystals were proposed almost two decades ago as a unique tool for controlling propagation and emission of light. Since then the research field of photonic crystals has exploded and many beautiful demonstrations of the use of photonic crystals and fibers for molding light...... propagation have appeared that hold great promises for integrated optics. These major achievements solidly demonstrate the ability to control propagation of light. In contrast, an experimental demonstration of the use of photonic crystals for timing the emission of light has so far lacked. In a recent...... publication in Nature, we have demonstrated experimentally that both the direction and time of spontaneous emission can be controlled, thereby confirming the original proposal by Eli Yablonovich that founded the field of photonic crystals. We believe that this work opens new opportunities for solid...

  5. Development and design of advanced two-photon microscope used in neuroscience

    International Nuclear Information System (INIS)

    Doronin, M S; Popov, A V

    2016-01-01

    This work represents the real steps to development and design advanced two-photon microscope by efforts of laboratory staff. Self-developed microscopy system provides possibility to service it and modify the structure of microscope depending on highly specialized experimental design and scientific goals. We are presenting here module-based microscopy system which provides an opportunity to looking for new applications of this setup depending on laboratories needs using with galvo and resonant scanners. (paper)

  6. Excitation of propagating surface plasmons with a scanning tunnelling microscope.

    Science.gov (United States)

    Wang, T; Boer-Duchemin, E; Zhang, Y; Comtet, G; Dujardin, G

    2011-04-29

    Inelastic electron tunnelling excitation of propagating surface plasmon polaritons (SPPs) on a thin gold film is demonstrated. This is done by combining a scanning tunnelling microscope (STM) with an inverted optical microscope. Analysis of the leakage radiation in both the image and Fourier planes unambiguously shows that the majority (up to 99.5%) of the detected photons originate from propagating SPPs with propagation lengths of the order of 10  µm. The remaining photon emission is localized under the STM tip and is attributed to a tip-gold film coupled plasmon resonance as evidenced by the bimodal spectral distribution and enhanced emission intensity observed using a silver STM tip for excitation.

  7. Excitation of propagating surface plasmons with a scanning tunnelling microscope

    International Nuclear Information System (INIS)

    Wang, T; Boer-Duchemin, E; Zhang, Y; Comtet, G; Dujardin, G

    2011-01-01

    Inelastic electron tunnelling excitation of propagating surface plasmon polaritons (SPPs) on a thin gold film is demonstrated. This is done by combining a scanning tunnelling microscope (STM) with an inverted optical microscope. Analysis of the leakage radiation in both the image and Fourier planes unambiguously shows that the majority (up to 99.5%) of the detected photons originate from propagating SPPs with propagation lengths of the order of 10 μm. The remaining photon emission is localized under the STM tip and is attributed to a tip-gold film coupled plasmon resonance as evidenced by the bimodal spectral distribution and enhanced emission intensity observed using a silver STM tip for excitation.

  8. Excitation of propagating surface plasmons with a scanning tunnelling microscope

    Energy Technology Data Exchange (ETDEWEB)

    Wang, T; Boer-Duchemin, E; Zhang, Y; Comtet, G; Dujardin, G, E-mail: Elizabeth.Boer-Duchemin@u-psud.fr [Institut des Sciences Moleculaire d' Orsay (ISMO), CNRS Universite Paris-Sud, 91405 Orsay (France)

    2011-04-29

    Inelastic electron tunnelling excitation of propagating surface plasmon polaritons (SPPs) on a thin gold film is demonstrated. This is done by combining a scanning tunnelling microscope (STM) with an inverted optical microscope. Analysis of the leakage radiation in both the image and Fourier planes unambiguously shows that the majority (up to 99.5%) of the detected photons originate from propagating SPPs with propagation lengths of the order of 10 {mu}m. The remaining photon emission is localized under the STM tip and is attributed to a tip-gold film coupled plasmon resonance as evidenced by the bimodal spectral distribution and enhanced emission intensity observed using a silver STM tip for excitation.

  9. Probing Field Distributions on Waveguide Structures with an Atomic Force/Photon Scanning Tunneling Microscope

    NARCIS (Netherlands)

    Borgonjen, E.G.; Borgonjen, E.G.; Moers, M.H.P.; Moers, M.H.P.; Ruiter, A.G.T.; van Hulst, N.F.

    1995-01-01

    A 'stand-alone' Photon Scanning Tunneling Microscope combined with an Atomic force Microscope, using a micro-fabricated silicon-nitride probe, is applied to the imaging of field distribution in integrated optical ridge waveguides. The electric field on the waveguide is locally probed by coupling to

  10. Photon enhanced thermionic emission

    Science.gov (United States)

    Schwede, Jared; Melosh, Nicholas; Shen, Zhixun

    2014-10-07

    Photon Enhanced Thermionic Emission (PETE) is exploited to provide improved efficiency for radiant energy conversion. A hot (greater than 200.degree. C.) semiconductor cathode is illuminated such that it emits electrons. Because the cathode is hot, significantly more electrons are emitted than would be emitted from a room temperature (or colder) cathode under the same illumination conditions. As a result of this increased electron emission, the energy conversion efficiency can be significantly increased relative to a conventional photovoltaic device. In PETE, the cathode electrons can be (and typically are) thermalized with respect to the cathode. As a result, PETE does not rely on emission of non-thermalized electrons, and is significantly easier to implement than hot-carrier emission approaches.

  11. Single-photon emission tomography and cerebral blood flow

    International Nuclear Information System (INIS)

    Celsis, P.; Chan, M.; Marc-Vergnes, J.P.; Sveinsdottir, E.; Goldman, T.G.; Henriksen, L.; Paulson, O.B.; Stokely, E.M.; Lassen, N.A.

    1982-01-01

    This paper illustrates the capabilities of single-photon emission tomography in imaging local cerebral blood flows in man. The results purport the conclusion that a fairly good improvement has been achieved when compared to stationary detectors and that single-photon emission tomography is a well-suited tool for studying cerebral hemodynamics, especially within the framework of clinical studies [fr

  12. Acoustic and photon emissions during mechanical deformation of coloured alkali halide crystals

    International Nuclear Information System (INIS)

    Chandra, B.P.

    1984-01-01

    Acoustic and photon emissions take place in the elastic and plastic as well as the fracture region of x-irradiated KBr, KCl and NaCl crystals. The rate of photon emission is linear with the strain rate: however, the RMS value of the acoustic emission is proportional to the square root of the strain rate. The acoustic emission is maximum for x-irradiated NaCl crystals; however, the photon emission is maximum for x-irradiated KBr crystals. From the similarity between the acoustic emission and the photon emission, it seems that mobile dislocations are responsible for the acoustic emission in coloured alkali halide crystals. (author)

  13. Role of spontaneous and stimulated emission in photon correlations

    International Nuclear Information System (INIS)

    Chopra, S.; Bohidar, H.; Harwalkar, V.

    1984-01-01

    Photon correlations have been alternately attributed to either spontaneous or stimulated emission by various authors. In this paper, the authors interpret, on the basis of available experimental data, the contribution of each emission form to the evolution of photon statistics. The laser is used as an example of a source which exhibits different statistical characteristics depending on the level of excitation, which is governed by the pump parameter a. From the data, it is evident that the transition from below to above threshold is accompanied by a significant drop in the magnitude of correlation and an increase in decay time. It may be noted that this transition causes a substantial increase in the coherent output which emphasizes the predominance of stimulated emission. In the case of a laser below threshold, however, photon correlations arise due to superposition of the more dominant spontaneously emitted wavetrains. Exact solutions of quantized systems do not exist in the presence of saturation effects. This implies that factorization and identification of terms with spontaneous or stimulated emission has not yet been done. This does not preculde a physical and intuitive interpretation of photon statistics within the framework of a standard model, and it is therefore argued that spontaneous emission is responsible for photon correlations while stimulated emission shows up in the dynamics as the coherence time

  14. Absorption and emission properties of photonic crystals and metamaterials

    International Nuclear Information System (INIS)

    Peng, Lili

    2007-01-01

    We study the emission and absorption properties of photonic crystals and metamaterials using Comsol Multiphysics and Ansoft HFSS as simulation tools. We calculate the emission properties of metallic designs using drude model and the results illustrate that an appropriate termination of the surface of the metallic structure can significantly increase the absorption and therefore the thermal emissivity. We investigate the spontaneous emission rate modifications that occur for emitters inside two-dimensional photonic crystals and find the isotropic and directional emissions with respect to different frequencies as we have expected.

  15. Photons emission processes in electron scattering

    International Nuclear Information System (INIS)

    Soto Vargas, C.W.

    1996-01-01

    The investigations involving the scattering sections arising in virtual an real photon emission processes of electron and positron scattering by an atomic nucleus, have the need for thorough and complete calculations of the virtual photon spectrum and then introduce the distorted wave formulation, which is mathematically involved an numerically elaborated, but accessible to its use in experimental electron scattering facilities. (author) [es

  16. Strong Photonic-Band-Gap Effect on the Spontaneous Emission in 3D Lead Halide Perovskite Photonic Crystals.

    Science.gov (United States)

    Zhou, Xue; Li, Mingzhu; Wang, Kang; Li, Huizeng; Li, Yanan; Li, Chang; Yan, Yongli; Zhao, Yongsheng; Song, Yanlin

    2018-03-25

    Stimulated emission in perovskite-embedded polymer opal structures is investigated. A polymer opal structure is filled with a perovskite, and perovskite photonic crystals are prepared. The spontaneous emission of the perovskite embedded in the polymer opal structures exhibits clear signatures of amplified spontaneous emission (ASE) via gain modulation. The difference in refractive-index contrast between the perovskite and the polymer opal is large enough for retaining photonic-crystals properties. The photonic band gap has a strong effect on the fluorescence emission intensity and lifetime. The stimulated emission spectrum exhibits a narrow ASE rather than a wide fluorescence peak in the thin film. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Femtosecond photoelectron point projection microscope

    International Nuclear Information System (INIS)

    Quinonez, Erik; Handali, Jonathan; Barwick, Brett

    2013-01-01

    By utilizing a nanometer ultrafast electron source in a point projection microscope we demonstrate that images of nanoparticles with spatial resolutions of the order of 100 nanometers can be obtained. The duration of the emission process of the photoemitted electrons used to make images is shown to be of the order of 100 fs using an autocorrelation technique. The compact geometry of this photoelectron point projection microscope does not preclude its use as a simple ultrafast electron microscope, and we use simple analytic models to estimate temporal resolutions that can be expected when using it as a pump-probe ultrafast electron microscope. These models show a significant increase in temporal resolution when comparing to ultrafast electron microscopes based on conventional designs. We also model the microscopes spectroscopic abilities to capture ultrafast phenomena such as the photon induced near field effect

  18. Spontaneous and light-induced photon emission from intact brains of chick embryos

    Institute of Scientific and Technical Information of China (English)

    张锦珠; 于文斗; 孙彤

    1997-01-01

    Photon emission (PE) and light-induced photon emission(LPE) of intact brains isolated from chick embryos have been measured by using the single photon counting device. Experimental results showed that the intensi-ty level of photon emission was detected to be higher from intact brain than from the medium in which the brain was immerged during measuring, and the emission intensity was related to the developmental stages, the healthy situation of the measured embryos, and the freshness of isolated brains as well. After white light illumination, a short-life de-layed emission from intact brains was observed, and its relaxation behavior followed a hyperbolic rather than an expo-nential law. According to the hypothesis of biophoton emission originating from a delocalized coherent electromagnetic field and Frohlich’s idea of coherent long-range interactions in biological systems, discussions were made on the signifi-cance of photon emission in studying cell communication, biological regulation, living system’

  19. Field electron emission spectrometer combined with field ion/electron microscope as a field emission laboratory

    International Nuclear Information System (INIS)

    Shkuratov, S.I.; Ivanov, S.N.; Shilimanov, S.N.

    1996-01-01

    The facility, combining the field ion microscope, field electron emission microscope and field electron emission spectrometer, is described. Combination of three methodologies makes it possible to carry out the complete cycle of emission studies. Atom-plane and clean surface of the studied samples is prepared by means of field evaporation of the material atom layers without any thermal and radiation impact. This enables the study of atom and electron structure of clean surface of the wide range materials, the study whereof through the field emission methods was previously rather difficult. The temperature of the samples under study changes from 75 up to 2500 K. The energy resolution of the electron analyzer equals 30 MeV. 19 refs., 10 figs

  20. Quantitative analysis of directional spontaneous emission spectra from light sources in photonic crystals

    International Nuclear Information System (INIS)

    Nikolaev, Ivan S.; Lodahl, Peter; Vos, Willem L.

    2005-01-01

    We have performed angle-resolved measurements of spontaneous-emission spectra from laser dyes and quantum dots in opal and inverse opal photonic crystals. Pronounced directional dependencies of the emission spectra are observed: angular ranges of strongly reduced emission adjoin with angular ranges of enhanced emission. It appears that emission from embedded light sources is affected both by the periodicity and by the structural imperfections of the crystals: the photons are Bragg diffracted by lattice planes and scattered by unavoidable structural disorder. Using a model comprising diffuse light transport and photonic band structure, we quantitatively explain the directional emission spectra. This work provides detailed understanding of the transport of spontaneously emitted light in real photonic crystals, which is essential in the interpretation of quantum optics in photonic-band-gap crystals and for applications wherein directional emission and total emission power are controlled

  1. Single-photon emission computed tomography

    International Nuclear Information System (INIS)

    Budinger, T.F.

    1986-01-01

    Single photon tomography dates from the early 1960's when the idea of emission transverse section tomography was presented by Kuhl and Edwards. They used a rectilinear scanner and analogue back-projection methods to detect emissions from a series of sequential positions transverse to the cephaldcaudad axis of the body. This chapter presents an explanation of emission tomography by describing longitudinal and transverse section tomography. In principle all modes of tomography can be considered under the general topic of coded apertures wherein the code ranges from translation of a pinhole collimator to rotation of a parallel hole or focused collimator array

  2. Optical microscope using an interferometric source of two-color, two-beam entangled photons

    Science.gov (United States)

    Dress, William B.; Kisner, Roger A.; Richards, Roger K.

    2004-07-13

    Systems and methods are described for an optical microscope using an interferometric source of multi-color, multi-beam entangled photons. A method includes: downconverting a beam of coherent energy to provide a beam of multi-color entangled photons; converging two spatially resolved portions of the beam of multi-color entangled photons into a converged multi-color entangled photon beam; transforming at least a portion of the converged multi-color entangled photon beam by interaction with a sample to generate an entangled photon specimen beam; and combining the entangled photon specimen beam with an entangled photon reference beam within a single beamsplitter. An apparatus includes: a multi-refringent device providing a beam of multi-color entangled photons; a condenser device optically coupled to the multi-refringent device, the condenser device converging two spatially resolved portions of the beam of multi-color entangled photons into a converged multi-color entangled photon beam; a beam probe director and specimen assembly optically coupled to the condenser device; and a beam splitter optically coupled to the beam probe director and specimen assembly, the beam splitter combining an entangled photon specimen beam from the beam probe director and specimen assembly with an entangled photon reference beam.

  3. Highly charged ion based time-of-flight emission microscope

    International Nuclear Information System (INIS)

    Hamza, Alex V.; Barnes, Alan V.; Magee, Ed; Newman, Mike; Schenkel, Thomas; McDonald, Joseph W.; Schneider, Dieter H.

    2000-01-01

    An emission microscope using highly charged ions as the excitation source has been designed, constructed, and operated. A novel ''acorn'' objective lens has been used to simultaneously image electron and secondary ion emission. A resistive anode-position sensitive detector is used to determine the x-y position and time of arrival of the secondary events at the microscope image plane. Contrast in the image can be based on the intensity of the electron emission and/or the presence of particular secondary ions. Spatial resolution of better than 1 μm and mass resolution m/Δm of better than 400 were demonstrated. Background rejection from uncorrelated events of greater than an order of magnitude is also achieved. (c) 2000 American Institute of Physics

  4. Selective scanning tunneling microscope light emission from rutile phase of VO2.

    Science.gov (United States)

    Sakai, Joe; Kuwahara, Masashi; Hotsuki, Masaki; Katano, Satoshi; Uehara, Yoichi

    2016-09-28

    We observed scanning tunneling microscope light emission (STM-LE) induced by a tunneling current at the gap between an Ag tip and a VO2 thin film, in parallel to scanning tunneling spectroscopy (STS) profiles. The 34 nm thick VO2 film grown on a rutile TiO2 (0 0 1) substrate consisted of both rutile (R)- and monoclinic (M)-structure phases of a few 10 nm-sized domains at room temperature. We found that STM-LE with a certain photon energy of 2.0 eV occurs selectively from R-phase domains of VO2, while no STM-LE was observed from M-phase. The mechanism of STM-LE from R-phase VO2 was determined to be an interband transition process rather than inverse photoemission or inelastic tunneling processes.

  5. Thermodynamics of photon-enhanced thermionic emission solar cells

    International Nuclear Information System (INIS)

    Reck, Kasper; Hansen, Ole

    2014-01-01

    Photon-enhanced thermionic emission (PETE) cells in which direct photon energy as well as thermal energy can be harvested have recently been suggested as a new candidate for high efficiency solar cells. Here, we present an analytic thermodynamical model for evaluation of the efficiency of PETE solar cells including an analysis of the entropy production due to thermionic emission of general validity. The model is applied to find the maximum efficiency of a PETE cell for given cathode and anode work functions and temperatures

  6. Zn doped GaN for single-photon emission

    Energy Technology Data Exchange (ETDEWEB)

    Behrends, Arne; Ledig, Johannes; Al-Suleiman, Mohamed Aid Mansur; Bakin, Andrey; Waag, Andreas [Institute of Semiconductor Technology, University of Technology Braunschweig, Hans-Sommer-Str. 66, 38106 Braunschweig (Germany); Peters, Silke; Racu, Ana Maria; Schmunk, Waldemar; Hofer, Helmut; Kueck, Stefan [Physikalisch Technische Bundesanstalt (PTB), Bundesallee 100, 38116 Braunschweig (Germany)

    2012-03-15

    In this work we report on the optical investigation of Zn doped GaN films fabricated by metal organic chemical vapor deposition. The samples show bright emission in the blue spectral range around 2.9 eV when Si codoping is provided. This emission is suggested to be used for single-photon emission, thus the density of the Zn-Si pairs was drastically reduced leading to a decrease of the blue luminescence. For electrically excited single-photon sources these Zn-Si pairs have to be incorporated into LEDs, therefore we fabricated GaN-based nano-LEDs which show electroluminescence at 430 nm (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  7. Photon event distribution sampling: an image formation technique for scanning microscopes that permits tracking of sub-diffraction particles with high spatial and temporal resolutions.

    Science.gov (United States)

    Larkin, J D; Publicover, N G; Sutko, J L

    2011-01-01

    In photon event distribution sampling, an image formation technique for scanning microscopes, the maximum likelihood position of origin of each detected photon is acquired as a data set rather than binning photons in pixels. Subsequently, an intensity-related probability density function describing the uncertainty associated with the photon position measurement is applied to each position and individual photon intensity distributions are summed to form an image. Compared to pixel-based images, photon event distribution sampling images exhibit increased signal-to-noise and comparable spatial resolution. Photon event distribution sampling is superior to pixel-based image formation in recognizing the presence of structured (non-random) photon distributions at low photon counts and permits use of non-raster scanning patterns. A photon event distribution sampling based method for localizing single particles derived from a multi-variate normal distribution is more precise than statistical (Gaussian) fitting to pixel-based images. Using the multi-variate normal distribution method, non-raster scanning and a typical confocal microscope, localizations with 8 nm precision were achieved at 10 ms sampling rates with acquisition of ~200 photons per frame. Single nanometre precision was obtained with a greater number of photons per frame. In summary, photon event distribution sampling provides an efficient way to form images when low numbers of photons are involved and permits particle tracking with confocal point-scanning microscopes with nanometre precision deep within specimens. © 2010 The Authors Journal of Microscopy © 2010 The Royal Microscopical Society.

  8. Frequency dependence of coherently amplified two-photon emission from hydrogen molecules

    Science.gov (United States)

    Hara, Hideaki; Miyamoto, Yuki; Hiraki, Takahiro; Masuda, Takahiko; Sasao, Noboru; Uetake, Satoshi; Yoshimi, Akihiro; Yoshimura, Koji; Yoshimura, Motohiko

    2017-12-01

    We investigate how the efficiency of coherently amplified two-photon emission depends on the frequency of one of the two emitted photons, namely the signal photon. This is done over the wavelength range of 5.048-10.21 μ m by using the vibrational transition of parahydrogen. The efficiency increases with the frequency of the signal photon. Considering experimental errors, our results are consistent with the theoretical prediction for the present experimental conditions. This study is an experimental demonstration of the frequency dependence of coherently amplified two-photon emission, and also presents its potential as a light source.

  9. Thermodynamics of photon-enhanced thermionic emission solar cells

    DEFF Research Database (Denmark)

    Reck, Kasper; Hansen, Ole

    2014-01-01

    Photon-enhanced thermionic emission (PETE) cells in which direct photon energy as well as thermal energy can be harvested have recently been suggested as a new candidate for high efficiency solar cells. Here, we present an analytic thermodynamical model for evaluation of the efficiency of PETE...

  10. Diagnosis of dementia with single photon emission computed tomography

    International Nuclear Information System (INIS)

    Jagust, W.J.; Budinger, T.F.; Reed, B.R.

    1987-01-01

    Single photon emission computed tomography is a practical modality for the study of physiologic cerebral activity in vivo. We utilized single photon emission computed tomography and N-isopropyl-p-iodoamphetamine iodine 123 to evaluate regional cerebral blood flow in nine patients with Alzheimer's disease (AD), five healthy elderly control subjects, and two patients with multi-infarct dementia. We found that all subjects with AD demonstrated flow deficits in temporoparietal cortex bilaterally, and that the ratio of activity in bilateral temporoparietal cortex to activity in the whole slice allowed the differentiation of all patients with AD from both the controls and from the patients with multi-infarct dementia. Furthermore, this ratio showed a strong correlation with disease severity in the AD group. Single photon emission computed tomography appears to be useful in the differential diagnosis of dementia and reflects clinical features of the disease

  11. Two-photon cooperative emission in the presence of athermal electromagnetic field

    International Nuclear Information System (INIS)

    Enaki, N.A.; Mihalache, D.

    1997-01-01

    The possibility of cooperative spontaneous two-photon emission of an extended radiators system and the influence of the external thermal electromagnetic field on the spontaneous emission rate, in such a system, are investigated. It is concluded that, in an external electromagnetic field, the two-photon cooperative emission rate increases significantly. The importance of this effect on the emission of gamma rays from inverted long-lived isomers triggered by X-ray thermal fields, is emphasized

  12. Stimulated emission depletion following two photon excitation

    OpenAIRE

    Marsh, R. J.; Armoogum, D. A.; Bain, A. J.

    2002-01-01

    The technique of stimulated emission depletion of fluorescence (STED) from a two photon excited molecular population is demonstrated in the S, excited state of fluorescein in ethylene glycol and methanol. Two photon excitation (pump) is achieved using the partial output of a regeneratively amplified Ti:Sapphire laser in conjunction with an optical parametric amplifier whose tuneable output provides a synchronous depletion (dump) pulse. Time resolved fluorescence intensity and anisotropy measu...

  13. Adapting a compact confocal microscope system to a two-photon excitation fluorescence imaging architecture.

    Science.gov (United States)

    Diaspro, A; Corosu, M; Ramoino, P; Robello, M

    1999-11-01

    Within the framework of a national National Institute of Physics of Matter (INFM) project, we have realised a two-photon excitation (TPE) fluorescence microscope based on a new generation commercial confocal scanning head. The core of the architecture is a mode-locked Ti:Sapphire laser (Tsunami 3960, Spectra Physics Inc., Mountain View, CA) pumped by a high-power (5 W, 532 nm) laser (Millennia V, Spectra Physics Inc.) and an ultracompact confocal scanning head, Nikon PCM2000 (Nikon Instruments, Florence, Italy) using a single-pinhole design. Three-dimensional point-spread function has been measured to define spatial resolution performances. The TPE microscope has been used with a wide range of excitable fluorescent molecules (DAPI, Fura-2, Indo-1, DiOC(6)(3), fluoresceine, Texas red) covering a single photon spectral range from UV to green. An example is reported on 3D imaging of the helical structure of the sperm head of the Octopus Eledone cirrhosa labelled with an UV excitable dye, i.e., DAPI. The system can be easily switched for operating both in conventional and two-photon mode. Copyright 1999 Wiley-Liss, Inc.

  14. Photon emission spectroscopy of ion-atom collisions

    International Nuclear Information System (INIS)

    Nystroem, B.

    1995-10-01

    Emission cross sections for the 1snp 1 P 1 -levels have been measured by photon emission spectroscopy for the collision systems He + + He at 10 keV and He 2+ + He at 10-35 keV. Photon spectra of Krypton (Kr VIII) and Xenon (Xe V - IX) have also been obtained using 10q keV beams of Kr q+ (q=7-9) and Xe q+ (q=5-9) colliding with Helium and Argon. The Lifetimes of 3p 2 P-levels in Na-like Nb are reported together with lifetime for the 3s3p 3 P 1 -level in Mg-like Ni, Kr, Y, Zr and Nb where this level has an intercombination transition to the ground state. 45 refs, 20 figs

  15. Role of delta excitations in pion-, photon- and nucleon-nucleus reactions studied with microscopic models

    International Nuclear Information System (INIS)

    Engel, A.

    1995-01-01

    Delta excitation plays a prominent role in intermediate heavy reactions. In this paper, comment is made on the calculations done for pion-, photon- and nucleon-nucleus reactions using the Boltzmann-Uehling-Uhlenbeck (BUU) model and the antisymmetrized molecular dynamics (AMD) model. First, it is recalled how to include delta degrees in microscopic models in general. Then, the comparison of the microscopic calculation performed by the author with the experimental data is presented. Deltas in microscopic models are discussed. Pion-nucleus reactions have been studied since pion beams became available, especially for exploring the delta resonance in a nuclear medium. The dependence of pion absorption cross section on incident pion energy is shown. The photon-induced pion production in the resonance energy region was studied with the BUU model. The calculated results of neutral pion photo-production are shown. In both inelastic proton scattering and (p,n) charge exchange reaction, the excitation of delta resonance can be observed clearly in the experimental data. The results of the AMD calculation for 12 C(p,p') reaction are shown. (K.I.)

  16. Wide-band acousto-optic deflectors for large field of view two-photon microscope.

    Science.gov (United States)

    Jiang, Runhua; Zhou, Zhenqiao; Lv, Xiaohua; Zeng, Shaoqun

    2012-04-01

    Acousto-optic deflector (AOD) is an attractive scanner for two-photon microscopy because it can provide fast and versatile laser scanning and does not involve any mechanical movements. However, due to the small scan range of available AOD, the field of view (FOV) of the AOD-based microscope is typically smaller than that of the conventional galvanometer-based microscope. Here, we developed a novel wide-band AOD to enlarge the scan angle. Considering the maximum acceptable acoustic attenuation in the acousto-optic crystal, relatively lower operating frequencies and moderate aperture were adopted. The custom AOD was able to provide 60 MHz 3-dB bandwidth and 80% peak diffraction efficiency at 840 nm wavelength. Based on a pair of such AOD, a large FOV two-photon microscope was built with a FOV up to 418.5 μm (40× objective). The spatiotemporal dispersion was compensated simultaneously with a single custom-made prism. By means of dynamic power modulation, the variation of laser intensity within the FOV was reduced below 5%. The lateral and axial resolution of the system were 0.58-2.12 μm and 2.17-3.07 μm, respectively. Pollen grain images acquired by this system were presented to demonstrate the imaging capability at different positions across the entire FOV. © 2012 American Institute of Physics

  17. Note: optical optimization for ultrasensitive photon mapping with submolecular resolution by scanning tunneling microscope induced luminescence.

    Science.gov (United States)

    Chen, L G; Zhang, C; Zhang, R; Zhang, X L; Dong, Z C

    2013-06-01

    We report the development of a custom scanning tunneling microscope equipped with photon collection and detection systems. The optical optimization includes the comprehensive design of aspherical lens for light collimation and condensing, the sophisticated piezo stages for in situ lens adjustment inside ultrahigh vacuum, and the fiber-free coupling of collected photons directly onto the ultrasensitive single-photon detectors. We also demonstrate submolecular photon mapping for the molecular islands of porphyrin on Ag(111) under small tunneling currents down to 10 pA and short exposure time down to 1.2 ms/pixel. A high quantum efficiency up to 10(-2) was also observed.

  18. Photon emission spectroscopy of ion-atom collisions

    Energy Technology Data Exchange (ETDEWEB)

    Nystroem, B

    1995-10-01

    Emission cross sections for the 1snp{sup 1}P{sub 1}-levels have been measured by photon emission spectroscopy for the collision systems He{sup +} + He at 10 keV and He{sup 2+} + He at 10-35 keV. Photon spectra of Krypton (Kr VIII) and Xenon (Xe V - IX) have also been obtained using 10q keV beams of Kr{sup q+} (q=7-9) and Xe{sup q+} (q=5-9) colliding with Helium and Argon. The Lifetimes of 3p{sup 2}P-levels in Na-like Nb are reported together with lifetime for the 3s3p{sup 3}P{sub 1}-level in Mg-like Ni, Kr, Y, Zr and Nb where this level has an intercombination transition to the ground state. 45 refs, 20 figs.

  19. A high performance, cost-effective, open-source microscope for scanning two-photon microscopy that is modular and readily adaptable.

    Directory of Open Access Journals (Sweden)

    David G Rosenegger

    Full Text Available Two-photon laser scanning microscopy has revolutionized the ability to delineate cellular and physiological function in acutely isolated tissue and in vivo. However, there exist barriers for many laboratories to acquire two-photon microscopes. Additionally, if owned, typical systems are difficult to modify to rapidly evolving methodologies. A potential solution to these problems is to enable scientists to build their own high-performance and adaptable system by overcoming a resource insufficiency. Here we present a detailed hardware resource and protocol for building an upright, highly modular and adaptable two-photon laser scanning fluorescence microscope that can be used for in vitro or in vivo applications. The microscope is comprised of high-end componentry on a skeleton of off-the-shelf compatible opto-mechanical parts. The dedicated design enabled imaging depths close to 1 mm into mouse brain tissue and a signal-to-noise ratio that exceeded all commercial two-photon systems tested. In addition to a detailed parts list, instructions for assembly, testing and troubleshooting, our plan includes complete three dimensional computer models that greatly reduce the knowledge base required for the non-expert user. This open-source resource lowers barriers in order to equip more laboratories with high-performance two-photon imaging and to help progress our understanding of the cellular and physiological function of living systems.

  20. A High Performance, Cost-Effective, Open-Source Microscope for Scanning Two-Photon Microscopy that Is Modular and Readily Adaptable

    Science.gov (United States)

    Rosenegger, David G.; Tran, Cam Ha T.; LeDue, Jeffery; Zhou, Ning; Gordon, Grant R.

    2014-01-01

    Two-photon laser scanning microscopy has revolutionized the ability to delineate cellular and physiological function in acutely isolated tissue and in vivo. However, there exist barriers for many laboratories to acquire two-photon microscopes. Additionally, if owned, typical systems are difficult to modify to rapidly evolving methodologies. A potential solution to these problems is to enable scientists to build their own high-performance and adaptable system by overcoming a resource insufficiency. Here we present a detailed hardware resource and protocol for building an upright, highly modular and adaptable two-photon laser scanning fluorescence microscope that can be used for in vitro or in vivo applications. The microscope is comprised of high-end componentry on a skeleton of off-the-shelf compatible opto-mechanical parts. The dedicated design enabled imaging depths close to 1 mm into mouse brain tissue and a signal-to-noise ratio that exceeded all commercial two-photon systems tested. In addition to a detailed parts list, instructions for assembly, testing and troubleshooting, our plan includes complete three dimensional computer models that greatly reduce the knowledge base required for the non-expert user. This open-source resource lowers barriers in order to equip more laboratories with high-performance two-photon imaging and to help progress our understanding of the cellular and physiological function of living systems. PMID:25333934

  1. Ultraweak photon emission as a non-invasive health assessment: A systematic review

    NARCIS (Netherlands)

    Ives, J.A.; Wijk, E.P.A. van; Bat, N.; Crawford, C.; Walter, A.; Jonas, W.B.; Wijk, R. van; Greef, J. van der

    2014-01-01

    We conducted a systematic review (SR) of the peer reviewed scientific literature on ultraweak photon emissions (UPE) from humans. The question was: Can ultraweak photon emissions from humans be used as a non-invasive health assessment? A systematic search was conducted across eight relevant

  2. Dynamics of Spontaneous Emission Controlled by Local Density of States in Photonic Crystals

    DEFF Research Database (Denmark)

    Lodahl, Peter; Nikolaev, Ivan S.; van Driel, A. Floris

    2006-01-01

    We have measured time-resolved spontaneous emission from quantum dots in 3D photonic crystals. Due to the spatially dependent local density of states, the distribution of decay rates varies strongly with the photonic crystal lattice parameter.......We have measured time-resolved spontaneous emission from quantum dots in 3D photonic crystals. Due to the spatially dependent local density of states, the distribution of decay rates varies strongly with the photonic crystal lattice parameter....

  3. Surface charge compensation for a highly charged ion emission microscope

    International Nuclear Information System (INIS)

    McDonald, J.W.; Hamza, A.V.; Newman, M.W.; Holder, J.P.; Schneider, D.H.G.; Schenkel, T.

    2003-01-01

    A surface charge compensation electron flood gun has been added to the Lawrence Livermore National Laboratory (LLNL) highly charged ion (HCI) emission microscope. HCI surface interaction results in a significant charge residue being left on the surface of insulators and semiconductors. This residual charge causes undesirable aberrations in the microscope images and a reduction of the Time-Of-Flight (TOF) mass resolution when studying the surfaces of insulators and semiconductors. The benefits and problems associated with HCI microscopy and recent results of the electron flood gun enhanced HCI microscope are discussed

  4. Factors affecting ultraviolet-A photon emission from β-irradiated human keratinocyte cells.

    Science.gov (United States)

    Le, M; Mothersill, C E; Seymour, C B; Ahmad, S B; Armstrong, A; Rainbow, A J; McNeill, F E

    2015-08-21

    The luminescence intensity of 340±5 nm photons emitted from HaCaT (human keratinocyte) cells was investigated using a single-photon-counting system during cellular exposure to (90)Y β-particles. Multiple factors were assessed to determine their influence upon the quantity and pattern of photon emission from β-irradiated cells. Exposure of 1 x 10(4) cells/5 mL to 703 μCi resulted in maximum UVA photoemission at 44.8 x 10(3)±2.5 x 10(3) counts per second (cps) from live HaCaT cells (background: 1-5 cps); a 16-fold increase above cell-free controls. Significant biophoton emission was achieved only upon stimulation and was also dependent upon presence of cells. UVA luminescence was measured for (90)Y activities 14 to 703 μCi where a positive relationship between photoemission and (90)Y activity was observed. Irradiation of live HaCaT cells plated at various densities produced a distinct pattern of emission whereby luminescence increased up to a maximum at 1 x 10(4) cells/5 mL and thereafter decreased. However, this result was not observed in the dead cell population. Both live and dead HaCaT cells were irradiated and were found to demonstrate different rates of photon emission at low β activities (⩽400 μCi). Dead cells exhibited greater photon emission rates than live cells which may be attributable to metabolic processes taking place to modulate the photoemissive effect. The results indicate that photon emission from HaCaT cells is perturbed by external stimulation, is dependent upon the activity of radiation delivered, the density of irradiated cells, and cell viability. It is postulated that biophoton emission may be modulated by a biological or metabolic process.

  5. Photonic engineering of highly linearly polarized quantum dot emission at telecommunication wavelengths

    Science.gov (United States)

    Mrowiński, P.; Emmerling, M.; Schneider, C.; Reithmaier, J. P.; Misiewicz, J.; Höfling, S.; Sek, G.

    2018-04-01

    In this work, we discuss a method to control the polarization anisotropy of spontaneous emission from neutral excitons confined in quantum-dot-like nanostructures, namely single epitaxial InAs quantum dashes emitting at telecom wavelengths. The nanostructures are embedded inside lithographically defined, in-plane asymmetric photonic mesa structures, which generate polarization-dependent photonic confinement. First, we study the influence of the photonic confinement on the polarization anisotropy of the emission by photoluminescence spectroscopy, and we find evidence of different contributions to a degree of linear polarization (DOLP), i.e., from the quantum dash and the photonic mesa, in total giving rise to DOLP =0.85 . Then, we perform finite-difference time-domain simulations of photonic confinement, and we calculate the DOLP in a dipole approximation showing well-matched results for the established model. Furthermore, by using numerical calculations, we demonstrate several types of photonic confinements where highly linearly polarized emission with DOLP of about 0.9 is possible by controlling the position of a quantum emitter inside the photonic structure. Then, we elaborate on anisotropic quantum emitters allowing for exceeding DOLP =0.95 in an optimized case, and we discuss the ways towards efficient linearly polarized single photon source at telecom bands.

  6. Measurement and model of the infrared two-photon emission spectrum of GaAs.

    Science.gov (United States)

    Hayat, Alex; Ginzburg, Pavel; Orenstein, Meir

    2009-07-10

    Two-photon emission from semiconductors was recently observed, but not fully interpreted. We develop a dressed-state model incorporating intraband scattering-related level broadening, yielding nondivergent emission rates. The spectrum calculations for high carrier concentrations including the time dependence of the screening buildup correspond well to our measured two-photon emission spectrum from GaAs.

  7. Modification of Thermal Emission via Metallic Photonic Crystals

    International Nuclear Information System (INIS)

    Norris, David J.; Stein, Andreas; George, Steven M.

    2012-01-01

    Photonic crystals are materials that are periodically structured on an optical length scale. It was previously demonstrated that the glow, or thermal emission, of tungsten photonic crystals that have a specific structure - known as the 'woodpile structure' - could be modified to reduce the amount of infrared radiation from the material. This ability has implications for improving the efficiency of thermal emission sources and for thermophotovoltaic devices. The study of this effect had been limited because the fabrication of metallic woodpile structures had previously required a complex fabrication process. In this project we pursued several approaches to simplify the fabrication of metallic photonic crystals that are useful for modification of thermal emission. First, we used the self-assembly of micrometer-scale spheres into colloidal crystals known as synthetic opals. These opals can then be infiltrated with a metal and the spheres removed to obtain a structure, known as an inverse opal, in which a three-dimensional array of bubbles is embedded in a film. Second, we used direct laser writing, in which the focus of an infrared laser is moved through a thin film of photoresist to form lines by multiphoton polymerization. Proper layering of such lines can lead to a scaffold with the woodpile structure, which can be coated with a refractory metal. Third, we explored a completely new approach to modified thermal emission - thin metal foils that contain a simple periodic surface pattern, as shown in Fig. 1. When such a foil is heated, surface plasmons are excited that propagate along the metal interface. If these waves strike the pattern, they can be converted into thermal emission with specific properties.

  8. Spontaneous emission control in a tunable hybrid photonic system

    NARCIS (Netherlands)

    Frimmer, M.; Koenderink, A.F.

    2013-01-01

    We experimentally demonstrate control of the rate of spontaneous emission in a tunable hybrid photonic system that consists of two canonical building blocks for spontaneous emission control, an optical antenna and a mirror, each providing a modification of the local density of optical states (LDOS).

  9. Simulating three-dimensional nonthermal high-energy photon emission in colliding-wind binaries

    Energy Technology Data Exchange (ETDEWEB)

    Reitberger, K.; Kissmann, R.; Reimer, A.; Reimer, O., E-mail: klaus.reitberger@uibk.ac.at [Institut für Astro- und Teilchenphysik and Institut für Theoretische Physik, Leopold-Franzens-Universität Innsbruck, A-6020 Innsbruck (Austria)

    2014-07-01

    Massive stars in binary systems have long been regarded as potential sources of high-energy γ rays. The emission is principally thought to arise in the region where the stellar winds collide and accelerate relativistic particles which subsequently emit γ rays. On the basis of a three-dimensional distribution function of high-energy particles in the wind collision region—as obtained by a numerical hydrodynamics and particle transport model—we present the computation of the three-dimensional nonthermal photon emission for a given line of sight. Anisotropic inverse Compton emission is modeled using the target radiation field of both stars. Photons from relativistic bremsstrahlung and neutral pion decay are computed on the basis of local wind plasma densities. We also consider photon-photon opacity effects due to the dense radiation fields of the stars. Results are shown for different stellar separations of a given binary system comprising of a B star and a Wolf-Rayet star. The influence of orbital orientation with respect to the line of sight is also studied by using different orbital viewing angles. For the chosen electron-proton injection ratio of 10{sup –2}, we present the ensuing photon emission in terms of two-dimensional projections maps, spectral energy distributions, and integrated photon flux values in various energy bands. Here, we find a transition from hadron-dominated to lepton-dominated high-energy emission with increasing stellar separations. In addition, we confirm findings from previous analytic modeling that the spectral energy distribution varies significantly with orbital orientation.

  10. X-ray generation by femtosecond laser pulses and its application to soft X-ray imaging microscope

    International Nuclear Information System (INIS)

    Ikeda, Kenichi; Kotaki, Hideyuki; Nakajima, Kazuhisa

    2002-01-01

    We have developed laser-produced plasma X-ray sources using femtosecond laser pulses at 10Hz repetition rate in a table-top size in order to investigate basic mechanism of X-ray emission from laser-matter interactions and its application to a X-ray microscope. In a soft X-ray region over 5 nm wavelength, laser-plasma X-ray emission from a solid target achieved an intense flux of photons of the order of 1011 photons/rad per pulse with duration of a few 100 ps, which is intense enough to make a clear imaging in a short time exposure. As an application of laser-produced plasma X-ray source, we have developed a soft X-ray imaging microscope operating in the wavelength range around 14 nm. The microscope consists of a cylindrically ellipsoidal condenser mirror and a Schwarzshird objective mirror with highly-reflective multilayers. We report preliminary results of performance tests of the soft X-ray imaging microscope with a compact laser-produced plasma X-ray source

  11. Spontaneous emission of quantum dots in disordered photonic crystal waveguides

    DEFF Research Database (Denmark)

    Sapienza, Luca; Nielsen, Henri Thyrrestrup; Stobbe, Søren

    2010-01-01

    We report on the enhancement of the spontaneous emission rate of single semiconductor quantum dots embedded in a photonic crystal waveguide with engineered disorder. Random high-Q cavities, that are signature of Anderson localization, are measured in photoluminescence experiments and appear...... in the slow light regime of the waveguide mode. Time resolved experiments show a 15-fold enhancement of the spontaneous emission rate, with coupling efficiencies of single photons into Anderson localized cavity modes of 94%. These results show that the performances of Anderson-localized cavities...

  12. On elementary act of stimulated emission

    International Nuclear Information System (INIS)

    Buzek, V.; Grigorijev, V.I.

    1984-11-01

    A microscopical description of stimulated emission in the framework of the modified Lee model is given. Besides this, the exact solutions in all sectors (n photons + atom) are obtained in the proposed model. (author)

  13. Photon emission statistics and photon tracking in single-molecule spectroscopy of molecular aggregates : Dimers and trimers

    NARCIS (Netherlands)

    Bloemsma, E. A.; Knoester, J.

    2012-01-01

    Based on the generating function formalism, we investigate broadband photon statistics of emission for single dimers and trimers driven by a continuous monochromatic laser field. In particular, we study the first and second moments of the emission statistics, which are the fluorescence excitation

  14. Theory of few photon dynamics in light emitting quantum dot devices

    Science.gov (United States)

    Carmele, Alexander; Richter, Marten; Sitek, Anna; Knorr, Andreas

    2009-10-01

    We present a modified cluster expansion to describe single-photon emitters in a semiconductor environment. We calculate microscopically to what extent semiconductor features in quantum dot-wetting layer systems alter the exciton and photon dynamics in comparison to the atom-like emission dynamics. We access these systems by the photon-probability-cluster-expansion: a reliable approach for few photon dynamics in many body electron systems. As a first application, we show that the amplitude of vacuum Rabi flops determines the number of electrons in the quantum dot.

  15. Directional emission of single photons from small atomic samples

    DEFF Research Database (Denmark)

    Miroshnychenko, Yevhen; V. Poulsen, Uffe; Mølmer, Klaus

    2013-01-01

    We provide a formalism to describe deterministic emission of single photons with tailored spatial and temporal profiles from a regular array of multi-level atoms. We assume that a single collective excitation is initially shared by all the atoms in a metastable atomic state, and that this state i...... is coupled by a classical laser field to an optically excited state which rapidly decays to the ground atomic state. Our model accounts for the different field polarization components via re-absorption and emission of light by the Zeeman manifold of optically excited states.......We provide a formalism to describe deterministic emission of single photons with tailored spatial and temporal profiles from a regular array of multi-level atoms. We assume that a single collective excitation is initially shared by all the atoms in a metastable atomic state, and that this state...

  16. single photon emission tomography and positron emission tomography - Part 1 (October 2012), Part 2 (October 2010)

    International Nuclear Information System (INIS)

    Buvat, Irene

    2010-10-01

    The objective of this lecture is to present the single photon emission computed tomography (SPECT) and the positron emission tomography (PET) imaging techniques. Part 1 Content: 1 - Introduction: anatomic, functional and molecular imaging; 2 - Radiotracers: chemical and physical constraints, gamma photon emitters, positon emitters, radioisotopes production, emitters type and imaging techniques; 3 - Gamma cameras; 4 - Quantification in emission tomography: attenuation, scattering, un-stationary spatial resolution; 5 - Synthesis and conclusion. Part 2 content: 1 - Positon emitters; 2 - Positons detection: Coincidence detection (electronic collimation, PET detectors with gamma cameras, dedicated PET detectors, spectrometry); PET detectors type; time-of-flight PET; 2D PET; 3D PET; 3 - Quantification in emission tomography: detected events, attenuation, scattering, fortuitous coincidences, standardisation; 4 - Common SPECT and PET problems: partial volume effect, movement, tomographic reconstruction, calibration, dead time; 5 - Synthesis and conclusion

  17. Simulation of multi-photon emission isotopes using time-resolved SimSET multiple photon history generator

    Energy Technology Data Exchange (ETDEWEB)

    Chiang, Chih-Chieh; Lin, Hsin-Hon; Lin, Chang-Shiun; Chuang, Keh-Shih [Department of Biomedical Engineering and Environmental Sciences, National Tsing-HuaUniversity, Hsinchu, Taiwan (China); Jan, Meei-Ling [Health Physics Division, Institute of Nuclear Energy Research, Atomic Energy Council, Taoyuan, Taiwan (China)

    2015-07-01

    Abstract-Multiple-photon emitters, such as In-111 or Se-75, have enormous potential in the field of nuclear medicine imaging. For example, Se-75 can be used to investigate the bile acid malabsorption and measure the bile acid pool loss. The simulation system for emission tomography (SimSET) is a well-known Monte Carlo simulation (MCS) code in nuclear medicine for its high computational efficiency. However, current SimSET cannot simulate these isotopes due to the lack of modeling of complex decay scheme and the time-dependent decay process. To extend the versatility of SimSET for simulation of those multi-photon emission isotopes, a time-resolved multiple photon history generator based on SimSET codes is developed in present study. For developing the time-resolved SimSET (trSimSET) with radionuclide decay process, the new MCS model introduce new features, including decay time information and photon time-of-flight information, into this new code. The half-life of energy states were tabulated from the Evaluated Nuclear Structure Data File (ENSDF) database. The MCS results indicate that the overall percent difference is less than 8.5% for all simulation trials as compared to GATE. To sum up, we demonstrated that time-resolved SimSET multiple photon history generator can have comparable accuracy with GATE and keeping better computational efficiency. The new MCS code is very useful to study the multi-photon imaging of novel isotopes that needs the simulation of lifetime and the time-of-fight measurements. (authors)

  18. Development of confocal laser microscope system for examination of microscopic characteristics of radiophotoluminescence glass dosemeters

    International Nuclear Information System (INIS)

    Maki, D.; Ishii, T.; Sato, F.; Kato, Y.; Yamamoto, T.; Iida, T.

    2011-01-01

    A confocal laser microscope system was developed for the measurement of radiophotoluminescence (RPL) photons emitted from a minute alpha-ray-irradiated area in an RPL glass dosemeter. The system was composed mainly of an inverted-type microscope, an ultraviolet laser, an XY movable stage and photon-counting circuits. The photon-counting circuits were effective in the reduction of the background noise level in the measurement of RPL photons. The performance of this microscope system was examined by the observation of standard RPL glass samples irradiated using 241 Am alpha rays. The spatial resolution of this system was ∼3 μm, and with regard to the sensitivity of this system, a hit of more than four to five alpha rays in unit area produced enough amount of RPL photons to construct the image. (authors)

  19. Development of confocal laser microscope system for examination of microscopic characteristics of radiophotoluminescence glass dosemeters.

    Science.gov (United States)

    Maki, Daisuke; Ishii, Tetsuya; Sato, Fuminobu; Kato, Yushi; Yamamoto, Takayoshi; Iida, Toshiyuki

    2011-03-01

    A confocal laser microscope system was developed for the measurement of radiophotoluminescence (RPL) photons emitted from a minute alpha-ray-irradiated area in an RPL glass dosemeter. The system was composed mainly of an inverted-type microscope, an ultraviolet laser, an XY movable stage and photon-counting circuits. The photon-counting circuits were effective in the reduction of the background noise level in the measurement of RPL photons. The performance of this microscope system was examined by the observation of standard RPL glass samples irradiated using (241)Am alpha rays. The spatial resolution of this system was ∼ 3 μm, and with regard to the sensitivity of this system, a hit of more than four to five alpha rays in unit area produced enough amount of RPL photons to construct the image.

  20. Correlated Photon Emission from Multiatom Rydberg Dark States

    DEFF Research Database (Denmark)

    Pritchard, J.D.; Adams, C.S.; Mølmer, Klaus

    2012-01-01

    We consider three-level atoms driven by two resonant light fields in a ladder scheme where the upper level is a highly excited Rydberg state. We show that the dipole-dipole interactions between Rydberg excited atoms prevents the formation of single particle dark states and leads to strongly corre...... correlated photon pairs from atoms separated by distances large compared to the emission wavelength. For a pair of atoms, this enables realization of an efficient photon-pair source with on average one pair every 30 μs....

  1. A compact scanning soft X-ray microscope

    International Nuclear Information System (INIS)

    Trail, J.A.

    1989-01-01

    Soft x-ray microscopes operating at wavelengths between 2.3 nm and 4.4 nm are capable of imaging wet biological cells with a resolution many times that of a visible light microscope. Several such soft x-ray microscopes have been constructed. However, with the exception of contact microscopes, all use synchrotrons as the source of soft x-ray radiation and Fresnel zone plates as the focusing optics. These synchrotron based microscopes are very successful but have the disadvantage of limited access. This dissertation reviews the construction and performance of a compact scanning soft x-ray microscope whose size and accessibility is comparable to that of an electron microscope. The microscope uses a high-brightness laser-produced plasma as the soft x-ray source and normal incidence multilayer-coated mirrors in a Schwarzschild configuration as the focusing optics. The microscope operates at a wavelength of 14 nm, has a spatial resolution of 0.5 μm, and has a soft x-ray photon flux through the focus of 10 4 -10 5 s -1 when operated with only 170 mW of average laser power. The complete system, including the laser, fits on a single 4' x 8' optical table. The significant components of the compact microscope are the laser-produced plasma (LPP) source, the multilayer coatings, and the Schwarzschild objective. These components are reviewed, both with regard to their particular use in the current microscope and with regard to extending the microscope performance to higher resolution, higher speed, and operation at shorter wavelengths. Measurements of soft x-ray emission and debris emission from our present LPP source are presented and considerations given for an optimal LPP source. The LPP source was also used as a broadband soft x-ray source for measurement of normal incidence multilayer mirror reflectance in the 10-25 nm spectral region

  2. Reliability Study of Mechatronic Power Components Using Spectral Photon Emission Microscopy

    Directory of Open Access Journals (Sweden)

    N. Moultif

    2016-11-01

    Full Text Available In this paper, we present one of the most important failure analysis tools that permits the localizing and the identification of the failure mechanisms. It is a new spectral photon emission system, enabling to localize the failure, and quickly get the photon emission spectra that characterize the failure with high resolution. A diffraction grating is used as a spectrometer in the system. Application results on mechatronic power devices such as HEMT AlGaN/GAN and SiC MOSFETs are reported.

  3. Polarized quantum dot emission in electrohydrodynamic jet printed photonic crystals

    International Nuclear Information System (INIS)

    See, Gloria G.; Xu, Lu; Nuzzo, Ralph G.; Sutanto, Erick; Alleyne, Andrew G.; Cunningham, Brian T.

    2015-01-01

    Tailored optical output, such as color purity and efficient optical intensity, are critical considerations for displays, particularly in mobile applications. To this end, we demonstrate a replica molded photonic crystal structure with embedded quantum dots. Electrohydrodynamic jet printing is used to control the position of the quantum dots within the device structure. This results in significantly less waste of the quantum dot material than application through drop-casting or spin coating. In addition, the targeted placement of the quantum dots minimizes any emission outside of the resonant enhancement field, which enables an 8× output enhancement and highly polarized emission from the photonic crystal structure

  4. Probe-Hole Field Emission Microscope System Controlled by Computer

    Science.gov (United States)

    Gong, Yunming; Zeng, Haishan

    1991-09-01

    A probe-hole field emission microscope system, controlled by an Apple II computer, has been developed and operated successfully for measuring the work function of a single crystal plane. The work functions on the clean W(100) and W(111) planes are measured to be 4.67 eV and 4.45 eV, respectively.

  5. Dirac directional emission in anisotropic zero refractive index photonic crystals.

    Science.gov (United States)

    He, Xin-Tao; Zhong, Yao-Nan; Zhou, You; Zhong, Zhi-Chao; Dong, Jian-Wen

    2015-08-14

    A certain class of photonic crystals with conical dispersion is known to behave as isotropic zero-refractive-index medium. However, the discrete building blocks in such photonic crystals are limited to construct multidirectional devices, even for high-symmetric photonic crystals. Here, we show multidirectional emission from low-symmetric photonic crystals with semi-Dirac dispersion at the zone center. We demonstrate that such low-symmetric photonic crystal can be considered as an effective anisotropic zero-refractive-index medium, as long as there is only one propagation mode near Dirac frequency. Four kinds of Dirac multidirectional emitters are achieved with the channel numbers of five, seven, eleven, and thirteen, respectively. Spatial power combination for such kind of Dirac directional emitter is also verified even when multiple sources are randomly placed in the anisotropic zero-refractive-index photonic crystal.

  6. Characterization of Strong Light-Matter Coupling in Semiconductor Quantum-Dot Microcavities via Photon-Statistics Spectroscopy

    Science.gov (United States)

    Schneebeli, L.; Kira, M.; Koch, S. W.

    2008-08-01

    It is shown that spectrally resolved photon-statistics measurements of the resonance fluorescence from realistic semiconductor quantum-dot systems allow for high contrast identification of the two-photon strong-coupling states. Using a microscopic theory, the second-rung resonance of Jaynes-Cummings ladder is analyzed and optimum excitation conditions are determined. The computed photon-statistics spectrum displays gigantic, experimentally robust resonances at the energetic positions of the second-rung emission.

  7. Transport and hydrodynamic calculations of direct photons at FAIR

    International Nuclear Information System (INIS)

    Baeuchle, Bjorn; Bleicher, Marcus

    2011-01-01

    The microscopic transport model UrQMD and a micro + macro hybrid model are used to calculate direct photon spectra from U+U-collisions at E lab =35 A GeV as will be measured by the CBM Collaboration at FAIR. In the hybrid model, the intermediate high-density part of the nuclear interaction is described with ideal 3+1-dimensional hydrodynamics. Different equations of state of the matter created in the heavy-ion collisions are investigated and the resulting spectra of direct photons are predicted. The emission patterns of direct photons in space and time are discussed.

  8. Quantitative single-photon emission tomography for cerebral flow and receptor distribution imaging

    International Nuclear Information System (INIS)

    Budinger, T.F.

    1985-01-01

    Recently there has been renewed interest in single-photon emission tomography for two major reasons. First, correction methods have been devised for attenuation compensation, nonuniform resolution, and scattered radiation. Second, new radiopharmaceuticals with 1-5% uptake in the brain provide adequate statistics for quantitative imaging of flow using properly designed single-photon tomographic instruments. The lack of commercially available instruments designed specifically to optimize sensitivity for a resolution finer than 15 mm full width at half maximum (FWHM) seems now to be the major deterrent to the widespread use of single-photon emission tomography. But it appears now that some development in this respect also might lead to a widespread renewed interest in single-photon tomography of the brain. Major activities of the past few years can be placed in three distinct categories of instrumentation and methodology

  9. Broadband enhancement of spontaneous emission in a photonic-plasmonic structure

    DEFF Research Database (Denmark)

    Zhu, Xiaolong; Xie, Fengxian; Shi, Lei

    2012-01-01

    We demonstrate that a broadband enhancement of spontaneous emission can be achieved within a photonic-plasmonic structure. The structure can strongly modify the spontaneous emission by exciting plasmonic modes. Because of the excited plasmonic modes, an enhancement up to 30 times is observed, lea......, leading to a 4 times broader emission spectrum. The reflectance measurement and the finite-difference time-domain simulation are carried out to support these results....

  10. Design of Slow and Fast Light Photonic Crystal Waveguides for Single-photon Emission Using a Bloch Mode Expansion Technique

    DEFF Research Database (Denmark)

    de Lasson, Jakob Rosenkrantz; Rigal, B.; Kapon, E.

    We design slow and fast light photonic crystal waveguides for single-photon emission using a Bloch mode expansion and scattering matrix technique. We propose slow light designs that increase the group index-waveguide mode volume ratio for larger Purcell enhancement, and address efficient slow-to-...

  11. Visible Light Emission from Atomic Scale Patterns Fabricated by the Scanning Tunneling Microscope

    DEFF Research Database (Denmark)

    Thirstrup, C.; Sakurai, M.; Stokbro, Kurt

    1999-01-01

    Scanning tunneling microscope (STM) induced light emission from artificial atomic scale structures comprising silicon dangling bonds on hydrogen-terminated Si(001) surfaces has been mapped spatially and analyzed spectroscopically in the visible spectral range. The light emission is based on a novel...

  12. Coherent effects on two-photon correlation and directional emission of two two-level atoms

    International Nuclear Information System (INIS)

    Ooi, C. H. Raymond; Kim, Byung-Gyu; Lee, Hai-Woong

    2007-01-01

    Sub- and superradiant dynamics of spontaneously decaying atoms are manifestations of collective many-body systems. We study the internal dynamics and the radiation properties of two atoms in free space. Interesting results are obtained when the atoms are separated by less than half a wavelength of the atomic transition, where the dipole-dipole interaction gives rise to new coherent effects, such as (a) coherence between two intermediate collective states, (b) oscillations in the two-photon correlation G (2) , (c) emission of two photons by one atom, and (d) the loss of directional correlation. We compare the population dynamics during the two-photon emission process with the dynamics of single-photon emission in the cases of a Λ and a V scheme. We compute the temporal correlation and angular correlation of two successively emitted photons using the G (2) for different values of atomic separation. We find antibunching when the atomic separation is a quarter wavelength λ/4. Oscillations in the temporal correlation provide a useful feature for measuring subwavelength atomic separation. Strong directional correlation between two emitted photons is found for atomic separation larger than a wavelength. We also compare the directionality of a photon spontaneously emitted by the two atoms prepared in phased-symmetric and phased-antisymmetric entangled states vertical bar ±> k 0 =e ik 0 ·r 1 vertical bar a 1 ,b 2 >±e ik 0 ·r 2 vertical bar b 1 ,a 2 > by a laser pulse with wave vector k 0 . Photon emission is directionally suppressed along k 0 for the phased-antisymmetric state. The directionality ceases for interatomic distances less than λ/2

  13. Quantification in single photon emission computed tomography (SPECT)

    International Nuclear Information System (INIS)

    Buvat, Irene

    2005-01-01

    The objective of this lecture is to understand the possibilities and limitations of the quantitative analysis of single photon emission computed tomography (SPECT) images. It is also to identify the conditions to be fulfilled to obtain reliable quantitative measurements from images. Content: 1 - Introduction: Quantification in emission tomography - definition and challenges; quantification biasing phenomena; 2 - quantification in SPECT, problems and correction methods: Attenuation, scattering, un-stationary spatial resolution, partial volume effect, movement, tomographic reconstruction, calibration; 3 - Synthesis: actual quantification accuracy; 4 - Beyond the activity concentration measurement

  14. Atlas of solar hidden photon emission

    Energy Technology Data Exchange (ETDEWEB)

    Redondo, Javier [Departamento de Física Teórica, Universidad de Zaragoza,Pedro Cerbuna 12, E-50009, Zaragoza (Spain); Max-Planck-Institut für Physik, Werner-Heisenberg-Institut,Föhringer Ring 6, 80805 München (Germany)

    2015-07-20

    Hidden photons, gauge bosons of a U(1) symmetry of a hidden sector, can constitute the dark matter of the universe and a smoking gun for large volume compactifications of string theory. In the sub-eV mass range, a possible discovery experiment consists on searching the copious flux of these particles emitted from the Sun in a helioscope setup à la Sikivie. In this paper, we compute in great detail the flux of HPs from the Sun, a necessary ingredient for interpreting such experiments. We provide a detailed exposition of transverse photon-HP oscillations in inhomogenous media, with special focus on resonance oscillations, which play a leading role in many cases. The region of the Sun emitting HPs resonantly is a thin spherical shell for which we justify an averaged-emission formula and which implies a distinctive morphology of the angular distribution of HPs on Earth in many cases. Low mass HPs with energies in the visible and IR have resonances very close to the photosphere where the solar plasma is not fully ionised and requires building a detailed model of solar refraction and absorption. We present results for a broad range of HP masses (from 0–1 keV) and energies (from the IR to the X-ray range), the most complete atlas of solar HP emission to date.

  15. Atlas of solar hidden photon emission

    Energy Technology Data Exchange (ETDEWEB)

    Redondo, Javier, E-mail: redondo@mpp.mpg.de [Departamento de Física Teórica, Universidad de Zaragoza, Pedro Cerbuna 12, E-50009, Zaragoza, España (Spain)

    2015-07-01

    Hidden photons, gauge bosons of a U(1) symmetry of a hidden sector, can constitute the dark matter of the universe and a smoking gun for large volume compactifications of string theory. In the sub-eV mass range, a possible discovery experiment consists on searching the copious flux of these particles emitted from the Sun in a helioscope setup à la Sikivie. In this paper, we compute in great detail the flux of HPs from the Sun, a necessary ingredient for interpreting such experiments. We provide a detailed exposition of transverse photon-HP oscillations in inhomogenous media, with special focus on resonance oscillations, which play a leading role in many cases. The region of the Sun emitting HPs resonantly is a thin spherical shell for which we justify an averaged-emission formula and which implies a distinctive morphology of the angular distribution of HPs on Earth in many cases. Low mass HPs with energies in the visible and IR have resonances very close to the photosphere where the solar plasma is not fully ionised and requires building a detailed model of solar refraction and absorption. We present results for a broad range of HP masses (from 0–1 keV) and energies (from the IR to the X-ray range), the most complete atlas of solar HP emission to date.

  16. Nonclassical photon streams using rephased amplified spontaneous emission

    International Nuclear Information System (INIS)

    Ledingham, Patrick M.; Naylor, William R.; Longdell, Jevon J.; Beavan, Sarah E.; Sellars, Matthew J.

    2010-01-01

    We present a fully quantum mechanical treatment of optically rephased photon echoes. These echoes exhibit noise due to amplified spontaneous emission; however, this noise can be seen as a consequence of the entanglement between the atoms and the output light. With a rephasing pulse one can get an 'echo' of the amplified spontaneous emission, leading to light with nonclassical correlations at points separated in time, which is of interest in the context of building wide bandwith quantum repeaters. We also suggest a wideband version of DLCZ protocol based on the same ideas.

  17. Two-photon excited fluorescence emission from hemoglobin

    Science.gov (United States)

    Sun, Qiqi; Zeng, Yan; Zhang, Wei; Zheng, Wei; Luo, Yi; Qu, Jianan Y.

    2015-03-01

    Hemoglobin, one of the most important proteins in blood, is responsible for oxygen transportation in almost all vertebrates. Recently, we discovered two-photon excited hemoglobin fluorescence and achieved label-free microvascular imaging based on the hemoglobin fluorescence. However, the mechanism of its fluorescence emission still remains unknown. In this work, we studied the two-photon excited fluorescence properties of the hemoglobin subunits, heme/hemin (iron (II)/(III) protoporphyrin IX) and globin. We first studied the properties of heme and the similar spectral and temporal characteristics of heme and hemoglobin fluorescence provide strong evidence that heme is the fluorophore in hemoglobin. Then we studied the fluorescence properties of hemin, globin and methemoglobin, and found that the hemin may have the main effect on the methemoglobin fluorescence and that globin has tryptophan fluorescence like other proteins. Finally, since heme is a centrosymmetric molecule, that the Soret band fluorescence of heme and hemoglobin was not observed in the single photon process in the previous study may be due to the parity selection rule. The discovery of heme two-photon excited fluorescence may open a new window for heme biology research, since heme as a cofactor of hemoprotein has many functions, including chemical catalysis, electron transfer and diatomic gases transportation.

  18. Design and performance of an ultra-flexible two-photon microscope for in vivo research

    Science.gov (United States)

    Mayrhofer, Johannes M.; Haiss, Florent; Haenni, Dominik; Weber, Stefan; Zuend, Marc; Barrett, Matthew J. P.; Ferrari, Kim David; Maechler, Philipp; Saab, Aiman S.; Stobart, Jillian L.; Wyss, Matthias T.; Johannssen, Helge; Osswald, Harald; Palmer, Lucy M.; Revol, Vincent; Schuh, Claus-Dieter; Urban, Claus; Hall, Andrew; Larkum, Matthew E.; Rutz-Innerhofer, Edith; Zeilhofer, Hanns Ulrich; Ziegler, Urs; Weber, Bruno

    2015-01-01

    We present a cost-effective in vivo two-photon microscope with a highly flexible frontend for in vivo research. Our design ensures fast and reproducible access to the area of interest, including rotation of imaging plane, and maximizes space for auxiliary experimental equipment in the vicinity of the animal. Mechanical flexibility is achieved with large motorized linear stages that move the objective in the X, Y, and Z directions up to 130 mm. 360° rotation of the frontend (rotational freedom for one axis) is achieved with the combination of a motorized high precision bearing and gearing. Additionally, the modular design of the frontend, based on commercially available optomechanical parts, allows straightforward updates to future scanning technologies. The design exceeds the mobility of previous movable microscope designs while maintaining high optical performance. PMID:26600989

  19. Soft Photons from transport and hydrodynamics at FAIR energies

    International Nuclear Information System (INIS)

    Grimm, Andreas; Bäuchle, Bjørn

    2013-01-01

    Direct photon spectra from uranium-uranium collisions at FAIR energies (E lab = 35 AGeV) are calculated within the hadronic Ultra-relativistic Quantum Molecular Dynamics transport model. In this microscopic model, one can optionally include a macroscopic intermediate hydrodynamic phase. The hot and dense stage of the collision is then modeled by a hydro dynamical calculation. Photon emission from transport-hydro hybrid calculations is examined for purely hadronic matter and matter that has a cross-over phase transition and a critical end point to deconfined and chirally restored matter at high temperatures. We find the photon spectra in both scenarios to be dominated by Bremsstrahlung. Comparing flow of photons in both cases suggests a way to distinguish these two scenarios.

  20. Broadband enhancement of single photon emission and polarization dependent coupling in silicon nitride waveguides.

    Science.gov (United States)

    Bisschop, Suzanne; Guille, Antoine; Van Thourhout, Dries; Hens, Zeger; Brainis, Edouard

    2015-06-01

    Single-photon (SP) sources are important for a number of optical quantum information processing applications. We study the possibility to integrate triggered solid-state SP emitters directly on a photonic chip. A major challenge consists in efficiently extracting their emission into a single guided mode. Using 3D finite-difference time-domain simulations, we investigate the SP emission from dipole-like nanometer-sized inclusions embedded into different silicon nitride (SiNx) photonic nanowire waveguide designs. We elucidate the effect of the geometry on the emission lifetime and the polarization of the emitted SP. The results show that highly efficient and polarized SP sources can be realized using suspended SiNx slot-waveguides. Combining this with the well-established CMOS-compatible processing technology, fully integrated and complex optical circuits for quantum optics experiments can be developed.

  1. Room-temperature light-emission from Ge quantum dots in photonic crystals

    Energy Technology Data Exchange (ETDEWEB)

    Xia Jinsong [Advanced Research Laboratories, Musashi Institute of Technolgy, 8-15-1 Todoroki, Setagaya-ku, Tokyo 158-0082 (Japan)], E-mail: jxia@sc.musashi-tech.ac.jp; Nemoto, Koudai; Ikegami, Yuta [Advanced Research Laboratories, Musashi Institute of Technolgy, 8-15-1 Todoroki, Setagaya-ku, Tokyo 158-0082 (Japan); Usami, Noritaka [Institute of Materials Research, Tohoku University, 2-2-1 Katahira, Aoba-ku, Sendai Japan (Japan)], E-mail: usa@imr.tohoku.ac.jp; Nakata, Yasushi [Horiba, Ltd., 1-7-8 Higashi-Kanda, Chiyoda-ku, Tokyo 101-0031 (Japan)], E-mail: yasushi.nakata@horiba.com; Shiraki, Yasuhiro [Advanced Research Laboratories, Musashi Institute of Technolgy, 8-15-1 Todoroki, Setagaya-ku, Tokyo 158-0082 (Japan)

    2008-11-03

    Multiple layers of Ge self-assembled quantum dots were embedded into two-dimensional silicon photonic crystal microcavities fabricated on silicon-on-insulator substrates. Microphotoluminescence was used to study the light-emission characteristic of the Ge quantum dots in the microcavities. Strong resonant room-temperature light-emission was observed in the telecommunication wavelength region. Significant enhancement of the luminescence from Ge dots was obtained due to the resonance in the cavities. Multiple sharp resonant peaks dominated the spectrum, showing strong optical resonance inside the cavity. By changing the lattice constant of photonic crystal structure, the wavelengths of the resonant peaks are tuned in the wide wavelength range from 1.2 to 1.6 {mu}m.

  2. Fabrication of silver tips for scanning tunneling microscope induced luminescence.

    Science.gov (United States)

    Zhang, C; Gao, B; Chen, L G; Meng, Q S; Yang, H; Zhang, R; Tao, X; Gao, H Y; Liao, Y; Dong, Z C

    2011-08-01

    We describe a reliable fabrication procedure of silver tips for scanning tunneling microscope (STM) induced luminescence experiments. The tip was first etched electrochemically to yield a sharp cone shape using selected electrolyte solutions and then sputter cleaned in ultrahigh vacuum to remove surface oxidation. The tip status, in particular the tip induced plasmon mode and its emission intensity, can be further tuned through field emission and voltage pulse. The quality of silver tips thus fabricated not only offers atomically resolved STM imaging, but more importantly, also allows us to perform challenging "color" photon mapping with emission spectra taken at each pixel simultaneously during the STM scan under relatively small tunnel currents and relatively short exposure time.

  3. A new approach to nuclear microscopy: The ion-electron emission microscope

    International Nuclear Information System (INIS)

    Doyle, B.L.; Vizkelethy, G.; Walsh, D.S.; Senftinger, B.; Mellon, M.

    1998-01-01

    A new multidimensional high lateral resolution ion beam analysis technique, Ion-Electron Emission Microscopy or IEEM is described. Using MeV energy ions, IEEM is shown to be capable of Ion Beam Induced Charge Collection (IBICC) measurements in semiconductors. IEEM should also be capable of microscopically and multidimensionally mapping the surface and bulk composition of solids. As such, IIEM has nearly identical capabilities as traditional nuclear microprobe analysis, with the advantage that the ion beam does not have to be focused. The technique is based on determining the position where an individual ion enters the surface of the sample by projection secondary electron emission microscopy. The x-y origination point of a secondary electron, and hence the impact coordinates of the corresponding incident ion, is recorded with a position sensitive detector connected to a standard photoemission electron microscope (PEEM). These signals are then used to establish coincidence with IBICC, atomic, or nuclear reaction induced ion beam analysis signals simultaneously caused by the incident ion

  4. Multiple photon emission and b-quark asymmetries

    International Nuclear Information System (INIS)

    Jadach, S.; Ward, B.F.L.

    1991-01-01

    Recently the authors have introduced methods at the level of an event-by-event simulator, the effects of multiple photon emission in Z o physics scenarios relevant to the SLC and LEP. And, indeed, the respective Monte-Carlo Fortran programs for the processes e + e - → f bar f + n(γ), f ≠ e, and e + e - → e + e - + n(γ) are, in fact available from the authors, for example, for the interested reader. The authors have illustrated the respective multiple-photon effects in the case that f = μ and in the Bhabha scattering case (the latter case is dealt with only at the low-angle scattering regime relevant to luminosity simulations). Here, the authors focus on the case e + e - → b bar b + n(γ) in the high-precision regime. Such high-precision considerations may be relevant to a high-luminosity upgrade of the LEP collider, for example. Such a high-luminosity upgrade of the SLC appears more remote at this time, according to the lore. In this paper, the authors review the elements of the methods they shall employ in the next section. The authors then discuss in the third section, the multiple-photon emission effects on the b-quark asymmetries of interest to the authors here. The interplay of the radiative effects and the detector cuts is realized by applying Mark II-type detector cuts. Here, in order to make the comparison with their earlier work on μ bar μ + nγ final states immediate, the authors impose the same μ like cuts on their b-quark. The authors realize that, in doing this, some of what the authors gain in immediacy the authors may lose in the proximity to reality. In any event, we do not lose contact with the effects of interest to the authors. Finally, the authors conclude with some summary remarks

  5. Microscopic approach to polaritons

    DEFF Research Database (Denmark)

    Skettrup, Torben

    1981-01-01

    contrary to experimental experience. In order to remove this absurdity the semiclassical approach must be abandoned and the electromagnetic field quantized. A simple microscopic polariton model is then derived. From this the wave function for the interacting exciton-photon complex is obtained...... of light of the crystal. The introduction of damping smears out the excitonic spectra. The wave function of the polariton, however, turns out to be very independent of damping up to large damping values. Finally, this simplified microscopic polariton model is compared with the exact solutions obtained...... for the macroscopic polariton model by Hopfield. It is seen that standing photon and exciton waves must be included in an exact microscopic polariton model. However, it is concluded that for practical purposes, only the propagating waves are of importance and the simple microscopic polariton wave function derived...

  6. Field emission from individual multiwalled carbon nanotubes prepared in an electron microscope

    NARCIS (Netherlands)

    de Jonge, N.; van Druten, N.J.

    2003-01-01

    Individual multiwalled carbon nanotube field emitters were prepared in a scanning electron microscope. The angular current density, energy spectra, and the emission stability of the field-emitted electrons were measured. An estimate of the electron source brightness was extracted from the

  7. Single Photon Source with a Diamond Nanocrystal on an Optical Nanofiber

    International Nuclear Information System (INIS)

    Lars Liebermeister

    2014-01-01

    The development of high yield single photon sources is crucial for applications in quantum information science as well as for experiments on the foundations of quantum physics. The NV-center in diamond is a promising solid state candidate. By using nanodiamonds the single photon emission can easily be coupled to integrated nano-optical and plasmonic structures. Our approach is to utilize efficient coupling of fluorescence of a single NV-center to the evanescent field of an optical nanofiber. A hybrid microscope (confocal microscope combined with an AFM) allows to optically characterize and preselect diamond nanocrystals and then to apply an AFM nanomanipulation technique to move a selected nanodiamond deterministically onto the tapered optical fiber. We report on first results with single diamond nanocrystals containing several NV-centers positioned on a tapered optical fiber. We observe fluorescence emission in the guided mode of the fiber. The second order correlation recorded between the free-space and the guided fluorescence shows pronounced antibunching. This demonstrated efficient evanescent coupling with low background. (author)

  8. Development of a two photon microscope for tracking Drosophila larvae

    Science.gov (United States)

    Karagyozov, Doycho; Mihovilovic Skanata, Mirna; Gershow, Marc

    Current in vivo methods for measuring neural activity in Drosophila larva require immobilization of the animal. Although we can record neural signals while stimulating the sensory organs, we cannot read the behavioral output because we have prevented the animal from moving. Many research questions cannot be answered without observation of neural activity in behaving (freely-moving) animals. We incorporated a Tunable Acoustic Gradient (TAG) lens into a two-photon microscope to achieve a 70kHz axial scan rate, enabling volumetric imaging at tens of hertz. We then implemented a tracking algorithm based on a Kalman filter to maintain the neurons of interest in the field of view and in focus during the rapid three dimensional motion of a free larva. Preliminary results show successful tracking of a neuron moving at speeds reaching 500 μm/s. NIH Grant 1DP2EB022359 and NSF Grant PHY-1455015.

  9. Mechanical design of a precision linear flexural stage for 3D x-ray diffraction microscope at the Advanced Photon Source

    Science.gov (United States)

    Shu, D.; Liu, W.; Kearney, S.; Anton, J.; Tischler, J. Z.

    2015-09-01

    The 3-D X-ray diffraction microscope is a new nondestructive tool for the three-dimensional characterization of mesoscopic materials structure. A flexural-pivot-based precision linear stage has been designed to perform a wire scan as a differential aperture for the 3-D diffraction microscope at the Advanced Photon Source, Argonne National Laboratory. The mechanical design and finite element analyses of the flexural stage, as well as its initial mechanical test results with laser interferometer are described in this paper.

  10. Anisotropic emission and photon-recycling in strain-balanced quantum well solar cells

    International Nuclear Information System (INIS)

    Cabrera, C. I.; Enciso, A.; Contreras-Solorio, D. A.; Rimada, J. C.; Hernandez, L.; Connolly, J. P.

    2014-01-01

    Strain-balanced quantum well solar cells (SB-QWSCs) extend the photon absorption edge beyond that of bulk GaAs by incorporation of quantum wells in the i-region of a p–i–n device. Anisotropy arises from a splitting of the valence band due to compressive strain in the quantum wells, suppressing a transition which contributes to emission from the edge of the quantum wells. We have studied both the emission light polarized in the plane perpendicular (TM) to the quantum well which couples exclusively to the light hole transition and the emission polarized in the plane of the quantum wells (TE) which couples mainly to the heavy hole transition. It was found that the spontaneous emission rates TM and TE increase when the quantum wells are deeper. The addition of a distributed Bragg reflector can substantially increase the photocurrent while decreasing the radiative recombination current. We have examined the impact of the photon recycling effect on SB-QWSC performance. We have optimized SB-QWSC design to achieve single junction efficiencies above 30%

  11. Anisotropic emission and photon-recycling in strain-balanced quantum well solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Cabrera, C. I.; Enciso, A.; Contreras-Solorio, D. A. [Academic Unit of Physics, Autonomous University of Zacatecas, Czda. Solidaridad y Paseo La Bufa S/N, 98060 Zacatecas, Zac. (Mexico); Rimada, J. C. [Solar Cell Laboratory, Institute of Materials Science and Technology (IMRE), University of Havana, Zapata y G, 10400 La Habana (Cuba); Hernandez, L., E-mail: luisman@fisica.uh.cu [Faculty of Physics, University of Havana, Colina Universitaria. 10400 La Habana (Cuba); Connolly, J. P. [Nanophotonics Technology Center, Universidad Politécnica de Valencia, 46022 Valencia (Spain)

    2014-04-28

    Strain-balanced quantum well solar cells (SB-QWSCs) extend the photon absorption edge beyond that of bulk GaAs by incorporation of quantum wells in the i-region of a p–i–n device. Anisotropy arises from a splitting of the valence band due to compressive strain in the quantum wells, suppressing a transition which contributes to emission from the edge of the quantum wells. We have studied both the emission light polarized in the plane perpendicular (TM) to the quantum well which couples exclusively to the light hole transition and the emission polarized in the plane of the quantum wells (TE) which couples mainly to the heavy hole transition. It was found that the spontaneous emission rates TM and TE increase when the quantum wells are deeper. The addition of a distributed Bragg reflector can substantially increase the photocurrent while decreasing the radiative recombination current. We have examined the impact of the photon recycling effect on SB-QWSC performance. We have optimized SB-QWSC design to achieve single junction efficiencies above 30%.

  12. Single photon emission computerized tomography

    International Nuclear Information System (INIS)

    Hooge, P. de.

    1983-01-01

    In this thesis two single-photon emission tomographic techniques are presented: (a) longitudinal tomography with a rotating slanting-hole collimator, and (b) transversal tomography with a rotating gamma camera. These methods overcome the disadvantages of conventional scintigraphy. Both detection systems and the image construction methods are explained and comparisons with conventional scintigraphy are drawn. One chapter is dedicated to the determination of system parameters like spatial resolution, contrast, detector uniformity, and size of the object, by phantom studies. In separate chapters the results are presented of detection of tumors and metastases in the liver and the liver hilus; skeletal diseases; various pathological aberrations of the brain; and myocardial perfusion. The possible use of these two ect's for other organs and body areas is discussed in the last chapter. (Auth.)

  13. Room-Temperature Single-Photon Emission from Micrometer-Long Air-Suspended Carbon Nanotubes

    Science.gov (United States)

    Ishii, A.; Uda, T.; Kato, Y. K.

    2017-11-01

    Statistics of photons emitted by mobile excitons in individual carbon nanotubes are investigated. Photoluminescence spectroscopy is used to identify the chiralities and suspended lengths of air-suspended nanotubes, and photon-correlation measurements are performed at room temperature on telecommunication-wavelength nanotube emission with a Hanbury-Brown-Twiss setup. We obtain zero-delay second-order correlation g(2 )(0 ) less than 0.5, indicating single-photon generation. Excitation power dependence of the photon antibunching characteristics is examined for nanotubes with various chiralities and suspended lengths, where we find that the minimum value of g(2 )(0 ) is obtained at the lowest power. The influence of exciton diffusion and end quenching is studied by Monte Carlo simulations, and we derive an analytical expression for the minimum value of g(2 )(0 ). Our results indicate that mobile excitons in micrometer-long nanotubes can in principle produce high-purity single photons, leading to new design strategies for quantum photon sources.

  14. Dynamically controlling the emission of single excitons in photonic crystal cavities

    NARCIS (Netherlands)

    Pagliano, F.; Cho, Y.; Xia, T.; Otten, van F.W.M.; Johne, R.; Fiore, A.

    2014-01-01

    Single excitons in semiconductor microcavities represent a solid state and scalable platform for cavity quantum electrodynamics, potentially enabling an interface between flying (photon) and static (exciton) quantum bits in future quantum networks. While both singlephoton emission and the strong

  15. Linoleic Acid-Induced Ultra-Weak Photon Emission from Chlamydomonas reinhardtii as a Tool for Monitoring of Lipid Peroxidation in the Cell Membranes

    Science.gov (United States)

    Prasad, Ankush; Pospíšil, Pavel

    2011-01-01

    Reactive oxygen species formed as a response to various abiotic and biotic stresses cause an oxidative damage of cellular component such are lipids, proteins and nucleic acids. Lipid peroxidation is considered as one of the major processes responsible for the oxidative damage of the polyunsaturated fatty acid in the cell membranes. Various methods such as a loss of polyunsaturated fatty acids, amount of the primary and the secondary products are used to monitor the level of lipid peroxidation. To investigate the use of ultra-weak photon emission as a non-invasive tool for monitoring of lipid peroxidation, the involvement of lipid peroxidation in ultra-weak photon emission was studied in the unicellular green alga Chlamydomonas reinhardtii. Lipid peroxidation initiated by addition of exogenous linoleic acid to the cells was monitored by ultra-weak photon emission measured with the employment of highly sensitive charged couple device camera and photomultiplier tube. It was found that the addition of linoleic acid to the cells significantly increased the ultra-weak photon emission that correlates with the accumulation of lipid peroxidation product as measured using thiobarbituric acid assay. Scavenging of hydroxyl radical by mannitol, inhibition of intrinsic lipoxygenase by catechol and removal of molecular oxygen considerably suppressed ultra-weak photon emission measured after the addition of linoleic acid. The photon emission dominated at the red region of the spectrum with emission maximum at 680 nm. These observations reveal that the oxidation of linoleic acid by hydroxyl radical and intrinsic lipoxygenase results in the ultra-weak photon emission. Electronically excited species such as excited triplet carbonyls are the likely candidates for the primary excited species formed during the lipid peroxidation, whereas chlorophylls are the final emitters of photons. We propose here that the ultra-weak photon emission can be used as a non-invasive tool for the

  16. Modeling vehicle fuel consumption and emissions at signalized intersection approaches : integrating field-collected data into microscopic simulation.

    Science.gov (United States)

    2012-07-01

    Microscopic models produce emissions and fuel consumption estimates with higher temporal resolution than other scales of : models. Most emissions and fuel consumption models were developed with data from dynamometer testing which are : sufficiently a...

  17. Modification of a scanning electron microscope to produce Smith-Purcell radiation

    International Nuclear Information System (INIS)

    Kapp, Oscar H.; Sun, Yin-e; Kim, Kwang-Je; Crewe, Albert V.

    2004-01-01

    We have modified a scanning electron microscope (SEM) in an attempt to produce a miniature free electron laser that can produce radiation in the far infrared region, which is difficult to obtain otherwise. This device is similar to the instrument studied by the Dartmouth group and functions on the basic principles first described by Smith and Purcell. The electron beam of the SEM is passed over a metal grating and should be capable of producing photons either in the spontaneous emission regime or in the superradiance regime if the electron beam is sufficiently bright. The instrument is capable of being continuously tuned by virtue of the period of the metal grating and the choice of accelerating voltage. The emitted Smith-Purcell photons exit the instrument via a polyethylene window and are detected by an infrared bolometer. Although we have obtained power levels exceeding nanowatts in the spontaneous emission regime, we have thus far not been able to detect a clear example of superradiance

  18. Interactions of low-power photons with natural opals—PBG materials, photonic control, natural metamaterials, spontaneous laser emissions, and band-gap boundary responses

    International Nuclear Information System (INIS)

    Stem, Michelle R.

    2012-01-01

    Four views of each of the opal research specimens in white light (for in-article or cover), in the same order as the specimens depicted in Fig. 3 of the main manuscript. A.On the left: 1.5 carat oval cabochon precious fire opal. B.In the center: 2.5 carats faceted fancy shield precious fire contra luz with mild adularescence. C.On the right: 5.0 carats round cabochon precious crystal opal with blue adularescence. Highlights: ► Emission of micro-lasers from microspheroid cluster boundary zones (quantum dots). ► Lasers illuminated or fluoresced the intra-opal structures of microspheroid photonic glass clusters. ► Microspheroid boundaries are durable to low power light sources. ► Display of previously unknown low power photonic optic properties. ► The research specimens are natural metamaterials. - Abstract: One overall goal of this research was to examine types of naturally-occurring opals that exhibit photonic control to learn about previously-unknown properties of naturally occurring photonic control that may be developed for broader applications. Three different photon sources were applied consecutively to three different types of natural, flawless, gem-quality precious opals. Two photon sources were lasers (green and red) and one was simulated daylight tungsten white. As each type of precious opal was exposed to each of the photon sources, the respective refractions, reflections, and transmissions were studied. This research is the first to show that applying various pleochroic and laser photon sources to these types of opals revealed significant information regarding naturally occurring photonic control, metamaterials, spontaneous laser emissions, and microspheroid cluster (inter-PBG zone) boundary effects. Plus, minimizing ambient light and the use of low power photon sources were critical to observing the properties regarding this photonic materials research. This research yielded information applicable to the development of materials to advance

  19. Scanning tunnelling microscope light emission: Finite temperature current noise and over cut-off emission.

    Science.gov (United States)

    Kalathingal, Vijith; Dawson, Paul; Mitra, J

    2017-06-14

    The spectral distribution of light emitted from a scanning tunnelling microscope junction not only bears its intrinsic plasmonic signature but is also imprinted with the characteristics of optical frequency fluc- tuations of the tunnel current. Experimental spectra from gold-gold tunnel junctions are presented that show a strong bias (V b ) dependence, curiously with emission at energies higher than the quantum cut-off (eV b ); a component that decays monotonically with increasing bias. The spectral evolution is explained by developing a theoretical model for the power spectral density of tunnel current fluctuations, incorporating finite temperature contribution through consideration of the quantum transport in the system. Notably, the observed decay of the over cut-off emission is found to be critically associated with, and well explained in terms of the variation in junction conductance with V b . The investigation highlights the scope of plasmon-mediated light emission as a unique probe of high frequency fluctuations in electronic systems that are fundamental to the electrical generation and control of plasmons.

  20. Single-Photon Emission Computerized Tomography (SPECT in Neuropsychiatry: A Review

    Directory of Open Access Journals (Sweden)

    B. K. Puri

    1992-01-01

    Full Text Available Cranial single-photon emission computerized tomography (SPECT or SPET can now give regional cerebral blood flow images with a resolution approaching that of positron emission tomography (PET. In this paper, the use of high resolution SPECT neuroimaging in neuropsychiatric disorders, including Alzheimer's disease, multi-infarct dementia, Pick's disease, progressive supranuclear palsy, Korsakoff's psychosis, Creutzfeld-Jakob disease, Parkinson's disease, Huntington's disease, schizophrenia, mood disorders, obsessive–compulsive disorder, HIV infection and AIDS is reviewed. Finally, further potential research and clinical uses, based on ligand studies, are outlined.

  1. CdSe quantum dot in vertical ZnSe nanowire and photonic wire for efficient single-photon emission

    DEFF Research Database (Denmark)

    Cremel, Thibault; Bellet-Amalric, Edith; Cagnon, Laurent

    conformal dielectric coating of Al2O3 on the NW-QDs using Atomic Layer Deposition so that a photonic wire is formed with the CdSe QD deterministically positioned on its axis. The collection enhancement effect is studied by measuring the emission (with pulse excitation, at saturation intensity) of single...

  2. High brightness single photon sources based on photonic wires

    DEFF Research Database (Denmark)

    Claudon, J.; Bleuse, J.; Bazin, M.

    2009-01-01

    We present a novel single-photon-source based on the emission of a semiconductor quantum dot embedded in a single-mode photonic wire. This geometry ensures a very large coupling (> 95%) of the spontaneous emission to the guided mode. Numerical simulations show that a photon collection efficiency...

  3. Design of Pixellated CMOS Photon Detector for Secondary Electron Detection in the Scanning Electron Microscope

    Directory of Open Access Journals (Sweden)

    Joon Huang Chuah

    2011-01-01

    Full Text Available This paper presents a novel method of detecting secondary electrons generated in the scanning electron microscope (SEM. The method suggests that the photomultiplier tube (PMT, traditionally used in the Everhart-Thornley (ET detector, is to be replaced with a configurable multipixel solid-state photon detector offering the advantages of smaller dimension, lower supply voltage and power requirements, and potentially cheaper product cost. The design of the proposed detector has been implemented using a standard 0.35 μm CMOS technology with optical enhancement. This microchip comprises main circuit constituents of an array of photodiodes connecting to respective noise-optimised transimpedance amplifiers (TIAs, a selector-combiner (SC circuit, and a postamplifier (PA. The design possesses the capability of detecting photons with low input optical power in the range of 1 nW with 100 μm × 100 μm sized photodiodes and achieves a total amplification of 180 dBΩ at the output.

  4. Designed Er(3+)-singly doped NaYF4 with double excitation bands for simultaneous deep macroscopic and microscopic upconverting bioimaging.

    Science.gov (United States)

    Wen, Xuanyuan; Wang, Baoju; Wu, Ruitao; Li, Nana; He, Sailing; Zhan, Qiuqiang

    2016-06-01

    Simultaneous deep macroscopic imaging and microscopic imaging is in urgent demand, but is challenging to achieve experimentally due to the lack of proper fluorescent probes. Herein, we have designed and successfully synthesized simplex Er(3+)-doped upconversion nanoparticles (UCNPs) with double excitation bands for simultaneous deep macroscopic and microscopic imaging. The material structure and the excitation wavelength of Er(3+)-singly doped UCNPs were further optimized to enhance the upconversion emission efficiency. After optimization, we found that NaYF4:30%Er(3+)@NaYF4:2%Er(3+) could simultaneously achieve efficient two-photon excitation (2PE) macroscopic tissue imaging and three-photon excitation (3PE) deep microscopic when excited by 808 nm continuous wave (CW) and 1480 nm CW lasers, respectively. In vitro cell imaging and in vivo imaging have also been implemented to demonstrate the feasibility and potential of the proposed simplex Er(3+)-doped UCNPs as bioprobe.

  5. Tracking biochemical changes correlated with ultra-weak photon emission using metabolomics

    Czech Academy of Sciences Publication Activity Database

    Burgos, R.C.R.; Červinková, Kateřina; van der Laan, T.; Ramautar, R.; van Wijk, E.P.A.; Cifra, Michal; Koval, S.; Berger, R.; Hankemeier, T.; van der Greef, J.

    -, č. 163 (2016), s. 237-245 ISSN 1011-1344 R&D Projects: GA ČR GA13-29294S Institutional support: RVO:67985882 Keywords : Ultra-weak photon emission * Capillary electrophoresis-mass spectrometry * HL-60 cells Subject RIV: BO - Biophysics Impact factor: 2.673, year: 2016

  6. Free radicals and low-level photon emission in human pathogenesis: state of the art.

    Science.gov (United States)

    Van Wijk, Roeland; Van Wijk, Eduard P A; Wiegant, Fred A C; Ives, John

    2008-05-01

    Convincing evidence supports a role for oxidative stress in the pathogenesis of many chronic diseases. The model includes the formation of radical oxygen species (ROS) and the misassembly and aggregation of proteins when three tiers of cellular defence are insufficient: (a) direct antioxidative systems, (b) molecular damage repairing systems, and (c) compensatory chaperone synthesis. The aim of the present overview is to introduce (a) the basics of free radical and antioxidant metabolism, (b) the role of the protein quality control system in protecting cells from free radical damage and its relation to chronic diseases, (c) the basics of the ultraweak luminescence as marker of the oxidant status of biological systems, and (d) the research in human photon emission as a non-invasive marker of oxidant status in relation to chronic diseases. In considering the role of free radicals in disease, both their generation and their control by the antioxidant system are part of the story. Excessive free radical production leads to the production of heat shock proteins and chaperone proteins as a second line of protection against damage. Chaperones at the molecular level facilitate stress regulation vis-à-vis protein quali y control mechanisms. The manifestation of misfolded proteins and aggregates is a hallmark of a range of neurodegenerative disorders including Alzheimer's disease, Parkinson's disease, amylotrophic lateral sclerosis, polyglutamine (polyQ) diseases, diabetes and many others. Each of these disorders exhibits aging-dependent onset and a progressive, usually fatal clinical course. The second part reviews the current status of human photon emission techniques and protocols for recording the human oxidative status. Sensitive photomultiplier tubes may provide a tool for non-invasive and continuous monitoring of oxidative metabolism. In that respect, recording ultraweak luminescence has been favored compared to other indirect assays. Several biological models have

  7. Nanoscale coupling of photons to vibrational excitation of Ag nanoparticle 2D array studied by scanning tunneling microscope light emission spectroscopy.

    Science.gov (United States)

    Katano, Satoshi; Toma, Koji; Toma, Mana; Tamada, Kaoru; Uehara, Yoichi

    2010-11-28

    Scanning tunneling microscope light emission (STM-LE) spectroscopy has been utilized to elucidate the luminescence phenomena of Ag nanoparticles capped with myristate (myristate-capped AgNP) and 2-methyl-1-propanethiolate (C(4)S-capped AgNP) on the dodecanethiol-precovered Au substrate. The STM imaging revealed that myristate-capped AgNPs form an ordered hexagonal array whereas C(4)S-capped AgNPs show imperfect ordering, indicating that a shorter alkyl chain of C(4)S-capped AgNP is not sufficient to form rigid interdigitation. It should be noted that such a nanoparticle ordering affects the luminescence properties of the Ag nanoparticle. We found that the STM-LE is only detected from the Ag nanoparticles forming the two-dimensional superlattice. This indicates that the STM-LE of the Ag nanoparticle is radiated via the collective excitation of the local surface plasmon resonance (LSPR) spread over the Ag nanoparticles. Note that the STM-LE spectra of the Ag nanoparticles exhibit spike-like peaks superimposed on the broad light emission peak. Using Raman spectroscopy, we concluded that the spike-like structure appearing in the STM-LE spectra is associated with the vibrational excitation of the molecule embedded between Ag nanoparticles.

  8. Half-life measurements and photon emission probabilities of frequently applied radioisotopes

    International Nuclear Information System (INIS)

    Schoetzig, U.; Schrader, H.

    1998-09-01

    It belongs to the duties of the PTB department for 'Radioactivity' to determine the radioactivity emitted by radioactive radiation sources and publish their specific decay data, also called ''standards'', so that appliers of such sources may calibrate their equipment accordingly, as e.g. photon detectors. Further data required for proper calibration are those defining the photon emission probability per decay, P(E), at the relevant photon energy E. The emission rate R(E) is derived from the activity A, by the calculus R(E)=A x P(E), and the half-lives of decay, T 1 /2, together with the standards are used for determining the time of measurement. The calibration quality essentially is determined by those two parameters and the incertainties involved. The PTB 'Radioactivity' department therefore publishes for users recommended decay data elaborated and used by the experts at PTB. The tabulated data are either measured at PTB, or critically selected from data compilations of other publication sources. The tabulated decay data presented here are intended to serve as a source of reference for laboratory work and should be used in combination with the comprehensive data collections available (see the bibliography of this document: 86BRFI, 91TECD, 96FI, Nuclear Data Sheets, e.g. 98ND84). (orig./CB) [de

  9. Linoleic acid-induced ultra-weak photon emission from Chlamydomonas reinhardtii as a tool for monitoring of lipid peroxidation in the cell membranes.

    Directory of Open Access Journals (Sweden)

    Ankush Prasad

    Full Text Available Reactive oxygen species formed as a response to various abiotic and biotic stresses cause an oxidative damage of cellular component such are lipids, proteins and nucleic acids. Lipid peroxidation is considered as one of the major processes responsible for the oxidative damage of the polyunsaturated fatty acid in the cell membranes. Various methods such as a loss of polyunsaturated fatty acids, amount of the primary and the secondary products are used to monitor the level of lipid peroxidation. To investigate the use of ultra-weak photon emission as a non-invasive tool for monitoring of lipid peroxidation, the involvement of lipid peroxidation in ultra-weak photon emission was studied in the unicellular green alga Chlamydomonas reinhardtii. Lipid peroxidation initiated by addition of exogenous linoleic acid to the cells was monitored by ultra-weak photon emission measured with the employment of highly sensitive charged couple device camera and photomultiplier tube. It was found that the addition of linoleic acid to the cells significantly increased the ultra-weak photon emission that correlates with the accumulation of lipid peroxidation product as measured using thiobarbituric acid assay. Scavenging of hydroxyl radical by mannitol, inhibition of intrinsic lipoxygenase by catechol and removal of molecular oxygen considerably suppressed ultra-weak photon emission measured after the addition of linoleic acid. The photon emission dominated at the red region of the spectrum with emission maximum at 680 nm. These observations reveal that the oxidation of linoleic acid by hydroxyl radical and intrinsic lipoxygenase results in the ultra-weak photon emission. Electronically excited species such as excited triplet carbonyls are the likely candidates for the primary excited species formed during the lipid peroxidation, whereas chlorophylls are the final emitters of photons. We propose here that the ultra-weak photon emission can be used as a non

  10. On the performance of bioanalytical fluorescence correlation spectroscopy measurements in a multiparameter photon-counting microscope

    Energy Technology Data Exchange (ETDEWEB)

    Mazouchi, Amir; Liu Baoxu; Bahram, Abdullah [Department of Physics, Institute for Optical Sciences, University of Toronto, Toronto (Canada); Department of Chemical and Physical Sciences, University of Toronto Mississauga, 3359 Mississauga Rd. N., Mississauga, ON, L5L 1C6 (Canada); Gradinaru, Claudiu C., E-mail: claudiu.gradinaru@utoronto.ca [Department of Physics, Institute for Optical Sciences, University of Toronto, Toronto (Canada); Department of Chemical and Physical Sciences, University of Toronto Mississauga, 3359 Mississauga Rd. N., Mississauga, ON, L5L 1C6 (Canada)

    2011-02-28

    Fluorescence correlation spectroscopy (FCS) data acquisition and analysis routines were developed and implemented in a home-built, multiparameter photon-counting microscope. Laser excitation conditions were investigated for two representative fluorescent probes, Rhodamine110 and enhanced green fluorescent protein (EGFP). Reliable local concentrations and diffusion constants were obtained by fitting measured FCS curves, provided that the excitation intensity did not exceed 20% of the saturation level for each fluorophore. Accurate results were obtained from FCS measurements for sample concentrations varying from pM to {mu}M range, as well as for conditions of high background signals. These experimental constraints were found to be determined by characteristics of the detection system and by the saturation behavior of the fluorescent probes. These factors actually limit the average number of photons that can be collected from a single fluorophore passing through the detection volume. The versatility of our setup and the data analysis capabilities were tested by measuring the mobility of EGFP in the nucleus of Drosophila cells under conditions of high concentration and molecular crowding. As a bioanalytical application, we studied by FCS the binding affinity of a novel peptide-based drug to the cancer-regulating STAT3 protein and corroborated the results with fluorescence polarization analysis derived from the same photon data.

  11. Flexible nanomembrane photonic-crystal cavities for tensilely strained-germanium light emission

    Energy Technology Data Exchange (ETDEWEB)

    Yin, Jian; Wang, Xiaowei; Paiella, Roberto [Department of Electrical and Computer Engineering and Photonics Center, Boston University, 8 Saint Mary' s Street, Boston, Massachusetts 02215 (United States); Cui, Xiaorui; Sookchoo, Pornsatit; Lagally, Max G. [Department of Materials Science and Engineering, University of Wisconsin – Madison, 1509 University Avenue, Madison, Wisconsin 53706 (United States)

    2016-06-13

    Flexible photonic-crystal cavities in the form of Si-column arrays embedded in polymeric films are developed on Ge nanomembranes using direct membrane assembly. The resulting devices can sustain large biaxial tensile strain under mechanical stress, as a way to enhance the Ge radiative efficiency. Pronounced emission peaks associated with photonic-crystal cavity resonances are observed in photoluminescence measurements. These results show that ultrathin nanomembrane active layers can be effectively coupled to an optical cavity, while still preserving their mechanical flexibility. Thus, they are promising for the development of strain-enabled Ge lasers, and more generally uniquely flexible optoelectronic devices.

  12. Perspectives: Nanofibers and nanowires for disordered photonics

    Directory of Open Access Journals (Sweden)

    Dario Pisignano

    2017-03-01

    Full Text Available As building blocks of microscopically non-homogeneous materials, semiconductor nanowires and polymer nanofibers are emerging component materials for disordered photonics, with unique properties of light emission and scattering. Effects found in assemblies of nanowires and nanofibers include broadband reflection, significant localization of light, strong and collective multiple scattering, enhanced absorption of incident photons, synergistic effects with plasmonic particles, and random lasing. We highlight recent related discoveries, with a focus on material aspects. The control of spatial correlations in complex assemblies during deposition, the coupling of modes with efficient transmission channels provided by nanofiber waveguides, and the embedment of random architectures into individually coded nanowires will allow the potential of these photonic materials to be fully exploited, unconventional physics to be highlighted, and next-generation optical devices to be achieved. The prospects opened by this technology include enhanced random lasing and mode-locking, multi-directionally guided coupling to sensors and receivers, and low-cost encrypting miniatures for encoders and labels.

  13. Multi-technique application of a double reflection electron emission microscope

    International Nuclear Information System (INIS)

    Jian-liang, J.; Bao-gui, S.; Guo-jun, Z

    2002-01-01

    Full text: In this paper the results acquired with the most recently developed double reflection electron emission microscope applied in different imaging modes are presented. The novel illumination system is based on a (100)-oriented single crystalline W wire electron microreflector and an electron gun placed in the back focal plane of the immersion objective. After being elastically reflected from the W tip surface, the primary electrons of energy ranging from 1 to 6 keV are decelerated to the desired impact energy in the range 0 to 200 eV for mirror electron microscopy (MEM), low energy electron emission microscopy (LEEM) and low energy electron diffraction (LEED) modes or to 5 keV for the secondary electron imaging mode. Photoelectron emission microscopy (PEEM), MEM, LEEM, secondary images of Pd/Si(111) and a set of selected area LEED patterns of the W(100) surface taken at energies ranging from 5 to 40 eV are presented for the first time. Copyright (2002) Australian Society for Electron Microscopy Inc

  14. On spontaneous photon emission in collapse models

    International Nuclear Information System (INIS)

    Adler, Stephen L; Bassi, Angelo; Donadi, Sandro

    2013-01-01

    We reanalyze the problem of spontaneous photon emission in collapse models. We show that the extra term found by Bassi and Dürr is present for non-white (colored) noise, but its coefficient is proportional to the zero frequency Fourier component of the noise. This leads one to suspect that the extra term is an artifact. When the calculation is repeated with the final electron in a wave packet and with the noise confined to a bounded region, the extra term vanishes in the limit of continuum state normalization. The result obtained by Fu and by Adler and Ramazanoğlu from application of the Golden Rule is then recovered. (paper)

  15. Photocount statistics of ultra-weak photon emission from germinating mung bean

    Czech Academy of Sciences Publication Activity Database

    Rafieiolhosseini, N.; Poplová, Michaela; Sasanpour, P.; Rafii-Tabar, H.; Alhossaini, M.R.; Cifra, Michal

    2016-01-01

    Roč. 162, September (2016), s. 50-55 ISSN 1011-1344 R&D Projects: GA ČR GA13-29294S Institutional support: RVO:67985882 Keywords : Mung bean * PMT photomultiplier tube * Abbreviations UPE ultra-weak photon emission Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 2.673, year: 2016

  16. Electrothermally Driven Fluorescence Switching by Liquid Crystal Elastomers Based On Dimensional Photonic Crystals.

    Science.gov (United States)

    Lin, Changxu; Jiang, Yin; Tao, Cheng-An; Yin, Xianpeng; Lan, Yue; Wang, Chen; Wang, Shiqiang; Liu, Xiangyang; Li, Guangtao

    2017-04-05

    In this article, the fabrication of an active organic-inorganic one-dimensional photonic crystal structure to offer electrothermal fluorescence switching is described. The film is obtained by spin-coating of liquid crystal elastomers (LCEs) and TiO 2 nanoparticles alternatively. By utilizing the property of LCEs that can change their size and shape reversibly under external thermal stimulations, the λ max of the photonic band gap of these films is tuned by voltage through electrothermal conversion. The shifted photonic band gap further changes the matching degree between the photonic band gap of the film and the emission spectrum of organic dye mounting on the film. With rhodamine B as an example, the enhancement factor of its fluorescence emission is controlled by varying the matching degree. Thus, the fluorescence intensity is actively switched by voltage applied on the system, in a fast, adjustable, and reversible manner. The control chain of using the electrothermal stimulus to adjust fluorescence intensity via controlling the photonic band gap is proved by a scanning electron microscope (SEM) and UV-vis reflectance. This mechanism also corresponded to the results from the finite-difference time-domain (FDTD) simulation. The comprehensive usage of photonic crystals and liquid crystal elastomers opened a new possibility for active optical devices.

  17. Hybrid plasmonic bullseye antennas for efficient photon collection

    DEFF Research Database (Denmark)

    Andersen, Sebastian Kim Hjælm; Bozhevolnyi, Sergey I.; Shalaev, Vladimir M.

    2018-01-01

    We propose highly efficient hybrid plasmonic bullseye antennas for collecting photon emission from nm sized quantum emitters. In our approach, the emitter radiation is coupled to surface plasmon polaritons that are consequently converted into highly directional out-of-plane emission. The proposed...... configuration consists of a high-index titania bullseye grating separated from a planar silver film by a thin low-index silica spacer layer. Such hybrid systems are theoretically capable of directing 85% of the dipole emission into a 0.9 NA objective, while featuring a spectrally narrow-band tunable decay rate...... stable operation. For experimental characterization of the antenna properties, a fluorescent nanodiamond containing multiple nitrogen vacancy centers (NV-center) was deterministically placed in the bullseye center, using an atomic force microscope. Probing the NV-center fluorescence we demonstrate...

  18. Electric-Field-Induced Energy Tuning of On-Demand Entangled-Photon Emission from Self-Assembled Quantum Dots.

    Science.gov (United States)

    Zhang, Jiaxiang; Zallo, Eugenio; Höfer, Bianca; Chen, Yan; Keil, Robert; Zopf, Michael; Böttner, Stefan; Ding, Fei; Schmidt, Oliver G

    2017-01-11

    We explore a method to achieve electrical control over the energy of on-demand entangled-photon emission from self-assembled quantum dots (QDs). The device used in our work consists of an electrically tunable diode-like membrane integrated onto a piezoactuator, which is capable of exerting a uniaxial stress on QDs. We theoretically reveal that, through application of the quantum-confined Stark effect to QDs by a vertical electric field, the critical uniaxial stress used to eliminate the fine structure splitting of QDs can be linearly tuned. This feature allows experimental realization of a triggered source of energy-tunable entangled-photon emission. Our demonstration represents an important step toward realization of a solid-state quantum repeater using indistinguishable entangled photons in Bell state measurements.

  19. Simulation Study of Single Photon Emission Computed Tomography for Industrial Applications

    International Nuclear Information System (INIS)

    Roy, Tushar; Sarkar, P. S.; Sinha, Amar

    2008-01-01

    SPECT (Single Photon Emission Computed Tomography) provides for an invaluable non-invasive technique for the characterization and activity distribution of the gamma-emitting source. For many applications of radioisotopes for medical and industrial application, not only the positional information of the distribution of radioisotopes is needed but also its strength. The well-established X-ray radiography or transmission tomography techniques do not yield sufficient quantitative information about these objects. Emission tomography is one of the important methods for such characterization. Application of parallel beam, fan beam and 3D cone beam emission tomography methods have been discussed in this paper. Simulation studies to test these algorithms have been carried out to validate the technique.

  20. LETTER TO THE EDITOR: Green emission and bandgap narrowing due to two-photon excitation in thin film CdS formed by spray pyrolysis

    Science.gov (United States)

    Ullrich, B.; Schroeder, R.

    2001-08-01

    Thin (10 µm) film CdS on Pyrex® formed by spray pyrolysis is excited below the gap at 804 nm with 200 fs laser pulses at room temperature. Excitation intensities up to 250 GW cm-2 evoke green bandgap emission due to two-photon transitions. This two-photon photoluminescence does not show a red emission contribution in contrast to the single-photon excited emission, which is dominated by broad emission in the red spectral range. It is demonstrated that two-photon excitation causes photo-induced bandgap narrowing due to Debye screening. At 250 GW cm-2 bandgap narrowing of 47 meV is observed, which corresponds to an excited electron density of 1.6×1018 cm-3.

  1. Spontaneous emission near the band edge of a three-dimensional photonic crystal: a fractional calculus approach

    International Nuclear Information System (INIS)

    Cheng, S-C; Wu, J-N; Tsai, M-R; Hsieh, W-F

    2009-01-01

    We suggest a better mathematical method, fractional calculus, for studying the behavior of the atom-field interaction in photonic crystals. By studying the spontaneous emission of an atom in a photonic crystal with a one-band isotropic model, we found that the long-time inducing memory of the spontaneous emission is a fractional phenomenon. This behavior could be well described by fractional calculus. The results show no steady photon-atom bound state for the atomic resonant transition frequency lying in the proximity of the allowed band edge which was encountered in a previous study (Woldeyohannes and John 2003 J. Opt. B: Quantum Semiclass. Opt. 5 R43). The correctness of this result is validated by the 'cut-off smoothing' density of photon states (DOS) with fractional calculus. By obtaining a rigorous solution without the multiple-valued problem for the system, we show that the method of fractional calculus has a logically concise property.

  2. Enhanced Photon Extraction from a Nanowire Quantum Dot Using a Bottom-Up Photonic Shell

    Science.gov (United States)

    Jeannin, Mathieu; Cremel, Thibault; Häyrynen, Teppo; Gregersen, Niels; Bellet-Amalric, Edith; Nogues, Gilles; Kheng, Kuntheak

    2017-11-01

    Semiconductor nanowires offer the possibility to grow high-quality quantum-dot heterostructures, and, in particular, CdSe quantum dots inserted in ZnSe nanowires have demonstrated the ability to emit single photons up to room temperature. In this paper, we demonstrate a bottom-up approach to fabricate a photonic fiberlike structure around such nanowire quantum dots by depositing an oxide shell using atomic-layer deposition. Simulations suggest that the intensity collected in our NA =0.6 microscope objective can be increased by a factor 7 with respect to the bare nanowire case. Combining microphotoluminescence, decay time measurements, and numerical simulations, we obtain a fourfold increase in the collected photoluminescence from the quantum dot. We show that this improvement is due to an increase of the quantum-dot emission rate and a redirection of the emitted light. Our ex situ fabrication technique allows a precise and reproducible fabrication on a large scale. Its improved extraction efficiency is compared to state-of-the-art top-down devices.

  3. Control of spontaneous emission from a microwave-field-driven four-level atom in an anisotropic photonic crystal

    Science.gov (United States)

    Zhang, Duo; Li, Jiahua; Ding, Chunling; Yang, Xiaoxue

    2012-05-01

    The spontaneous emission properties of a microwave-field-driven four-level atom embedded in anisotropic double-band photonic crystals (PCs) are investigated. We discuss the influences of the band-edge positions, Rabi frequency and detuning of the microwave field on the emission spectrum. It is found that several interesting features such as spectral-line enhancement, spectral-line suppression, spectral-line overlap, and multi-peak structures can be observed in the spectra. The proposed scheme can be achieved by use of a microwave-coupled field into hyperfine levels in rubidium atom confined in a photonic crystal. These theoretical investigations may provide more degrees of freedom to manipulate the atomic spontaneous emission.

  4. Photonic band gap materials: Technology, applications and challenges

    International Nuclear Information System (INIS)

    Johri, M.; Ahmed, Y.A.; Bezboruah, T.

    2006-05-01

    Last century has been the age of Artificial Materials. One material that stands out in this regard is the semiconductor. The revolution in electronic industry in the 20th century was made possible by the ability of semiconductors to microscopically manipulate the flow of electrons. Further advancement in the field made scientists suggest that the new millennium will be the age of photonics in which artificial materials will be synthesized to microscopically manipulate the flow of light. One of these will be Photonic Band Gap material (PBG). PBG are periodic dielectric structures that forbid propagation of electromagnetic waves in a certain frequency range. They are able to engineer most fundamental properties of electromagnetic waves such as the laws of refraction, diffraction, and emission of light from atoms. Such PBG material not only opens up variety of possible applications (in lasers, antennas, millimeter wave devices, efficient solar cells photo-catalytic processes, integrated optical communication etc.) but also give rise to new physics (cavity electrodynamics, localization, disorder, photon-number-state squeezing). Unlike electronic micro-cavity, optical waveguides in a PBG microchip can simultaneously conduct hundreds of wavelength channels of information in a three dimensional circuit path. In this article we have discussed some aspects of PBG materials and their unusual properties, which provided a foundation for novel practical applications ranging from clinical medicine to information technology. (author)

  5. Quantum squeezed state analysis of spontaneous ultra weak light photon emission of practitioners of meditation and control subjects.

    Science.gov (United States)

    Van Wijk, Eduard P A; Van Wijk, Roeland; Bajpai, Rajendra P

    2008-05-01

    Research on human ultra-weak photon emission (UPE) has suggested a typical human emission anatomic percentage distribution pattern. It was demonstrated that emission intensities are lower in long-term practitioners of meditation as compared to control subjects. The percent contribution of emission from different anatomic locations was not significantly different for meditation practitioners and control subjects. Recently, a procedure was developed to analyze the fluctuations in the signals by measuring probabilities of detecting different numbers of photons in a bin and correct these for background noise. The procedure was tested utilizing the signal from three different body locations of a single subject, demonstrating that probabilities have non-classical features and are well described by the signal in a coherent state from the three body sites. The values indicate that the quantum state of photon emitted by the subject could be a coherent state in the subject being investigated. The objective in the present study was to systematically quantify, in subjects with long-term meditation experience and subjects without this experience, the photon count distribution of 12 different locations. Data show a variation in quantum state parameters within each individual subject as well as variation in quantum state parameters between the groups.

  6. Design and development of compact multiphoton microscopes

    Science.gov (United States)

    Mehravar, SeyedSoroush

    A compact multi-photon microscope (MPM) was designed and developed with the use of low-cost mode-locked fiber lasers operating at 1040nm and 1560nm. The MPM was assembled in-house and the system aberration was investigated using the optical design software: Zemax. A novel characterization methodology based on 'nonlinear knife-edge' technique was also introduced to measure the axial, lateral resolution, and the field curvature of the multi-photon microscope's image plane. The field curvature was then post-corrected using data processing in MATLAB. A customized laser scanning software based on LabVIEW was developed for data acquisition, image display and controlling peripheral electronics. Finally, different modalities of multi-photon excitation such as second- and third harmonic generation, two- and three-photon fluorescence were utilized to study a wide variety of samples from cancerous cells to 2D-layered materials.

  7. Quantum Optics with Photonic Nanowires and Photonic Trumpets: Basics and Applications

    DEFF Research Database (Denmark)

    Gerard, J.; Claudon, J.; Munsch, M.

    , the node of future quantum networks. Besides optical microcavities [1], photonic wires have recently demonstrated in this context an appealing potential [2, 3]. For instance, single photon sources (SPS) based on a single quantum dot in a vertical photonic wire with integrated bottom mirror and tapered tip...... have enabled for the ¯rst time to achieve simultaneously a very high e±ciency (0.72 photon per pulse) and a very pure single photon emission (g(2)(0) control of the spontaneous emission of embedded emitters [4...

  8. Control of spontaneous emission from a microwave-field-driven four-level atom in an anisotropic photonic crystal

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Duo, E-mail: zhangduo10@gmail.com [Wuhan National Laboratory for Optoelectronics and School of Physics, Huazhong University of Science and Technology, Wuhan 430074 (China); School of Electrical and Electronic Engineering, Wuhan Polytechnic University, Wuhan 430023 (China); Li, Jiahua, E-mail: huajia_li@163.com [Wuhan National Laboratory for Optoelectronics and School of Physics, Huazhong University of Science and Technology, Wuhan 430074 (China); Ding, Chunling; Yang, Xiaoxue [Wuhan National Laboratory for Optoelectronics and School of Physics, Huazhong University of Science and Technology, Wuhan 430074 (China)

    2012-05-21

    The spontaneous emission properties of a microwave-field-driven four-level atom embedded in anisotropic double-band photonic crystals (PCs) are investigated. We discuss the influences of the band-edge positions, Rabi frequency and detuning of the microwave field on the emission spectrum. It is found that several interesting features such as spectral-line enhancement, spectral-line suppression, spectral-line overlap, and multi-peak structures can be observed in the spectra. The proposed scheme can be achieved by use of a microwave-coupled field into hyperfine levels in rubidium atom confined in a photonic crystal. These theoretical investigations may provide more degrees of freedom to manipulate the atomic spontaneous emission. -- Highlights: ► Spontaneous emission properties of an atom embedded in PCs are investigated. ► Spectral-line enhancement, suppression and overlapping are observed. ► The results provide more degrees of freedom to control atomic spontaneous emission.

  9. Control of spontaneous emission from a microwave-field-driven four-level atom in an anisotropic photonic crystal

    International Nuclear Information System (INIS)

    Zhang, Duo; Li, Jiahua; Ding, Chunling; Yang, Xiaoxue

    2012-01-01

    The spontaneous emission properties of a microwave-field-driven four-level atom embedded in anisotropic double-band photonic crystals (PCs) are investigated. We discuss the influences of the band-edge positions, Rabi frequency and detuning of the microwave field on the emission spectrum. It is found that several interesting features such as spectral-line enhancement, spectral-line suppression, spectral-line overlap, and multi-peak structures can be observed in the spectra. The proposed scheme can be achieved by use of a microwave-coupled field into hyperfine levels in rubidium atom confined in a photonic crystal. These theoretical investigations may provide more degrees of freedom to manipulate the atomic spontaneous emission. -- Highlights: ► Spontaneous emission properties of an atom embedded in PCs are investigated. ► Spectral-line enhancement, suppression and overlapping are observed. ► The results provide more degrees of freedom to control atomic spontaneous emission.

  10. Frequency splitter based on the directional emission from surface modes in dielectric photonic crystal structures.

    Science.gov (United States)

    Tasolamprou, Anna C; Zhang, Lei; Kafesaki, Maria; Koschny, Thomas; Soukoulis, Costas M

    2015-06-01

    We demonstrate the numerical design and the experimental validation of frequency dependent directional emission from a dielectric photonic crystal structure. The wave propagates through a photonic crystal line-defect waveguide, while a surface layer at the termination of the photonic crystal enables the excitation of surface modes and a subsequent grating layer transforms the surface energy into outgoing propagating waves of the form of a directional beam. The angle of the beam is controlled by the frequency and the structure operates as a frequency splitter in the intermediate and far field region.

  11. A dark-field microscope for background-free detection of resonance fluorescence from single semiconductor quantum dots operating in a set-and-forget mode.

    Science.gov (United States)

    Kuhlmann, Andreas V; Houel, Julien; Brunner, Daniel; Ludwig, Arne; Reuter, Dirk; Wieck, Andreas D; Warburton, Richard J

    2013-07-01

    Optically active quantum dots, for instance self-assembled InGaAs quantum dots, are potentially excellent single photon sources. The fidelity of the single photons is much improved using resonant rather than non-resonant excitation. With resonant excitation, the challenge is to distinguish between resonance fluorescence and scattered laser light. We have met this challenge by creating a polarization-based dark-field microscope to measure the resonance fluorescence from a single quantum dot at low temperature. We achieve a suppression of the scattered laser exceeding a factor of 10(7) and background-free detection of resonance fluorescence. The same optical setup operates over the entire quantum dot emission range (920-980 nm) and also in high magnetic fields. The major development is the outstanding long-term stability: once the dark-field point has been established, the microscope operates for days without alignment. The mechanical and optical designs of the microscope are presented, as well as exemplary resonance fluorescence spectroscopy results on individual quantum dots to underline the microscope's excellent performance.

  12. A dark-field microscope for background-free detection of resonance fluorescence from single semiconductor quantum dots operating in a set-and-forget mode

    International Nuclear Information System (INIS)

    Kuhlmann, Andreas V.; Houel, Julien; Warburton, Richard J.; Brunner, Daniel; Ludwig, Arne; Reuter, Dirk; Wieck, Andreas D.

    2013-01-01

    Optically active quantum dots, for instance self-assembled InGaAs quantum dots, are potentially excellent single photon sources. The fidelity of the single photons is much improved using resonant rather than non-resonant excitation. With resonant excitation, the challenge is to distinguish between resonance fluorescence and scattered laser light. We have met this challenge by creating a polarization-based dark-field microscope to measure the resonance fluorescence from a single quantum dot at low temperature. We achieve a suppression of the scattered laser exceeding a factor of 10 7 and background-free detection of resonance fluorescence. The same optical setup operates over the entire quantum dot emission range (920–980 nm) and also in high magnetic fields. The major development is the outstanding long-term stability: once the dark-field point has been established, the microscope operates for days without alignment. The mechanical and optical designs of the microscope are presented, as well as exemplary resonance fluorescence spectroscopy results on individual quantum dots to underline the microscope's excellent performance

  13. Record number (11 000) of interference fringes obtained by a 1 MV field-emission electron microscope

    International Nuclear Information System (INIS)

    Akashi, Tetsuya; Harada, Ken; Matsuda, Tsuyoshi; Kasai, Hiroto; Tonomura, Akira; Furutsu, Tadao; Moriya, Noboru; Yoshida, Takaho; Kawasaki, Takeshi; Kitazawa, Koichi; Koinuma, Hideomi

    2002-01-01

    An electron biprism for a 1 million-volt field-emission electron microscope was developed. This biprism is controlled similarly as a specimen holder so that it can be driven and rotated precisely and is tough against mechanical vibration and stray magnetic field. We recorded the maximum number of interference fringes by using this biprism in order to confirm the overall performance as a holography electron microscope, and obtained a world record of 11,000 interference fringes

  14. On the excess photon noise in single-beam measurements with photo-emissive and photo-conductive cells

    NARCIS (Netherlands)

    Alkemade, C.T.J.

    In this paper the so-called excess photon noise is theoretically considered with regard to noise power measurements with a single, illumined photo-emissive or photo-conductive cell. Starting from a modification of Mandel's stochastic association of the emission of photo-electrons with wave

  15. Slow-light enhancement of spontaneous emission in active photonic crystal waveguides

    DEFF Research Database (Denmark)

    Ek, Sara; Chen, Yaohui; Semenova, Elizaveta

    2012-01-01

    Photonic crystal defect waveguides with embedded active layers containing single or multiple quantum wells or quantum dots have been fabricated. Spontaneous emission spectra are enhanced close to the bandedge, consistently with the enhancement of gain by slow light effects. These are promising...... results for future compact devices for terabit/s communication, such as miniaturised semiconductor optical amplifiers and mode-locked lasers....

  16. Light emission probing quantum shot noise and charge fluctuations at a biased molecular junction

    DEFF Research Database (Denmark)

    Schneider, N.L.; Lu, Jing Tao; Brandbyge, M.

    2012-01-01

    The emission of plasmonic light from a single C60 molecule on Cu(111) is probed in a scanning tunneling microscope from the weak-coupling, tunneling range to strong coupling of the molecule to the electrodes at contact. At positive sample voltage the photon yield decreases owing to shot...

  17. Enhanced single-photon emission from a diamond–silver aperture

    KAUST Repository

    Choy, Jennifer T.

    2011-10-09

    Solid-state quantum emitters, such as the nitrogen-vacancy centre in diamond, are robust systems for practical realizations of various quantum information processing protocols2-5 and nanoscale magnetometry schemes6,7 at room temperature. Such applications benefit from the high emission efficiency and flux of single photons, which can be achieved by engineering the electromagnetic environment of the emitter. One attractive approach is based on plasmonic resonators8-13, in which sub-wavelength confinement of optical fields can strongly modify the spontaneous emission of a suitably embedded dipole despite having only modest quality factors. Meanwhile, the scalability of solid-state quantum systems critically depends on the ability to control such emitterg-cavity interaction in a number of devices arranged in parallel. Here, we demonstrate a method to enhance the radiative emission rate of single nitrogen-vacancy centres in ordered arrays of plasmonic apertures that promises greater scalability over the previously demonstrated bottom-up approaches for the realization of on-chip quantum networks. © 2011 Macmillan Publishers Limited. All rights reserved.

  18. Enhanced single-photon emission from a diamond–silver aperture

    KAUST Repository

    Choy, Jennifer T.; Hausmann, Birgit J. M.; Babinec, Thomas M.; Bulu, Irfan; Khan, Mughees; Maletinsky, Patrick; Yacoby, Amir; Lončar, Marko

    2011-01-01

    Solid-state quantum emitters, such as the nitrogen-vacancy centre in diamond, are robust systems for practical realizations of various quantum information processing protocols2-5 and nanoscale magnetometry schemes6,7 at room temperature. Such applications benefit from the high emission efficiency and flux of single photons, which can be achieved by engineering the electromagnetic environment of the emitter. One attractive approach is based on plasmonic resonators8-13, in which sub-wavelength confinement of optical fields can strongly modify the spontaneous emission of a suitably embedded dipole despite having only modest quality factors. Meanwhile, the scalability of solid-state quantum systems critically depends on the ability to control such emitterg-cavity interaction in a number of devices arranged in parallel. Here, we demonstrate a method to enhance the radiative emission rate of single nitrogen-vacancy centres in ordered arrays of plasmonic apertures that promises greater scalability over the previously demonstrated bottom-up approaches for the realization of on-chip quantum networks. © 2011 Macmillan Publishers Limited. All rights reserved.

  19. Development and design of up-to-date laser scanning two-photon microscope using in neuroscience

    Science.gov (United States)

    Doronin, Maxim; Popov, Alexander

    2017-02-01

    Today one of the main areas of application of two-photon microscopy is biology. This is due to the fact that this technique allows to obtain 3D images of tissues due to laser focus change, that is possible due to substantially greater penetration depth on the main wavelength into biological tissues. Self-developed microscopy system provides possibility to service it and modify the structure of microscope depending on highly specialized experimental design and scientific goals. This article may be regarded as a quick reference to laboratory staff who are wishing to develop their own microscopy system for self-service and modernization of the system and in order to save the lab budget.

  20. Quantified measurement of brain blood volume: comparative evaluations between the single photon emission computer tomography and the positron computer tomography

    International Nuclear Information System (INIS)

    Bouvard, G.; Fernandez, Y.; Petit-Taboue, M.C.; Derlon, J.M.; Travere, J.M.; Le Poec, C.

    1991-01-01

    The quantified measurement of cerebral blood volume is interesting for the brain blood circulation studies. This measurement is often used in positron computed tomography. It's more difficult in single photon emission computed tomography: there are physical problems with the limited resolution of the detector, the Compton effect and the photon attenuation. The objectif of this study is to compare the results between these two techniques. The quantified measurement of brain blood volume is possible with the single photon emission computer tomogragry. However, there is a loss of contrast [fr

  1. Analysis of borophosphosilicate glass layers on silicon wafers by X-ray emission from photon and electron excitation

    International Nuclear Information System (INIS)

    Elgersma, O.; Borstrok, J.J.M.

    1989-01-01

    Phosphorus and oxygen concentrations in the homogeneous layer of borosilicate glass (BPSG) deposited on Si-integrated circuits are determined by X-ray fluorescence from photon excitation. The X-ray emission from electron excitation in an open X-ray tube instrument yields a sufficiently precise determination of the boron content. The thickness of the layer can be derived from silicon Kα-fluorescence. A calibration model is proposed for photon as well as for electron excitation. The experimentally determined parameters in this model well agree with those derived from fundamental parameters for X-ray absorption and emission. The chemical surrounding of silicon affects strongly the peak profile of the silicon Kβ-emission. This enables to distinguish emission from the silicon atoms in the wafer and from the silicon atoms in the silicon oxide complexes of the BPSG-layer. (author)

  2. DE-BLURRING SINGLE PHOTON EMISSION COMPUTED TOMOGRAPHY IMAGES USING WAVELET DECOMPOSITION

    Directory of Open Access Journals (Sweden)

    Neethu M. Sasi

    2016-02-01

    Full Text Available Single photon emission computed tomography imaging is a popular nuclear medicine imaging technique which generates images by detecting radiations emitted by radioactive isotopes injected in the human body. Scattering of these emitted radiations introduces blur in this type of images. This paper proposes an image processing technique to enhance cardiac single photon emission computed tomography images by reducing the blur in the image. The algorithm works in two main stages. In the first stage a maximum likelihood estimate of the point spread function and the true image is obtained. In the second stage Lucy Richardson algorithm is applied on the selected wavelet coefficients of the true image estimate. The significant contribution of this paper is that processing of images is done in the wavelet domain. Pre-filtering is also done as a sub stage to avoid unwanted ringing effects. Real cardiac images are used for the quantitative and qualitative evaluations of the algorithm. Blur metric, peak signal to noise ratio and Tenengrad criterion are used as quantitative measures. Comparison against other existing de-blurring algorithms is also done. The simulation results indicate that the proposed method effectively reduces blur present in the image.

  3. Simple and versatile modifications allowing time gated spectral acquisition, imaging and lifetime profiling on conventional wide-field microscopes

    International Nuclear Information System (INIS)

    Pal, Robert; Beeby, Andrew

    2014-01-01

    An inverted microscope has been adapted to allow time-gated imaging and spectroscopy to be carried out on samples containing responsive lanthanide probes. The adaptation employs readily available components, including a pulsed light source, time-gated camera, spectrometer and photon counting detector, allowing imaging, emission spectroscopy and lifetime measurements. Each component is controlled by a suite of software written in LabVIEW and is powered via conventional USB ports. (technical note)

  4. Low-frequency-field-induced spontaneous-emission interference in a two-level atom placed in an anisotropic photonic crystal

    International Nuclear Information System (INIS)

    Li Gaoxiang; Evers, Joerg; Keitel, Christoph H

    2005-01-01

    We investigate the spontaneous-emission properties of a two-level atom embedded in a three-dimensional anisotropic photonic crystal. In addition to the modified density of states, the atom is driven by a coherent intense low-frequency field (LFF), which creates additional multiphoton decay channels with the exchange of two low-frequency photons and one spontaneous photon during an atomic transition. Due to the low frequency of the applied field, the various transition pathways may interfere with each other and thus give rise to a modified system dynamics. We find that even if all the atomic (bare and induced) transition frequencies are in the conducting band of the photonic crystal, there still may exist a photon-atom bound state in coexistence with propagating modes. The system also allows us to generate narrow lines in the spontaneous-emission spectrum. This spectrum is a function of the distance of the observer from the atom due to the band gap in the photonic crystal. The system properties depend on three characteristic frequencies, which are influenced by quantum interference effects. Thus these results can be attributed to a combination of interference and band-gap effects

  5. Photon and neutrino emission from active galactic nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Biermann, Peter L. [MPI for Radioastronomy, Bonn (Germany); Becker, Julia K. [Inst. for Phys., Univ. Bochum, Bochum (Germany); Caramete, Laurentiu I. [MPI for Radioastronomy, Bonn (Germany); Fraschetti, Federico [Inst. for Phys., Univ. Bochum, Bochum (Germany); Kneiske, Tanja [Inst. fuer Exp.Physik, Univ. Hamburg, Hamburg (Germany); Meli, Athina [Erlangen Center for Astroparticle Physics, University Erlangen-Nuremberg (Germany); Stanev, Todor [Bartol Research Inst., Univ. of Delaware, Newark, DE (United States)

    2011-08-15

    Supermassive black holes in the centers of galaxies are very common. They are known to rotate, accrete, spin down and eject highly relativistic jets; those jets pointed at us all seem to show a spectrum with two strong bumps, one in the TeV photon range, and one in X-rays - ordered by the emission frequency of the first bump this constitutes the blazar sequence. Here we wish to explain this sequence as primary synchrotron emission of energetic electrons and protons, and secondary emission from interactions at the first strong shockwave pattern in the relativistic jet. With two key assumptions on particle scattering, this concept predicts that the two basic maximum peak frequencies {nu}{sub syn,e,p} scale with the mass of the central black hole as {nu}{sub e,p{approx}}M{sub BH}{sup -1/2}, of {nu}{sub syn,p}/{nu}{sub syn,e}=(m{sub p}/m{sub e}){sup 3}, and the luminosities with the mass itself L{sub e,p{approx}}M{sub BH}. Due to strong losses of the leptons, the peak luminosities are generally the same, but with large variations around equality. This model predicts large fluxes in ultra high energy cosmic rays, and also large neutrino luminosities.

  6. Enhanced emission of high-energy photons perpendicular to the reaction plane in α+Th reactions

    International Nuclear Information System (INIS)

    Tegner, P.; Marianski, B.; Morsch, H.P.; Rogge, M.; Bargholtz, C.; Decowski, P.; Zemlo, L.

    1991-01-01

    High-energy photon and neutron emission has been measured in coincidence with fission fragments in α+ 232 Th reactions at 170 MeV. From measurements parallel and perpendicular to the fission plane, anisotropies relative to the reaction plane were determined. The in-plane/out-of-plane intensity ratio is 0.72(7) for photons with energies above 20 MeV and 11(3) for neutrons at 35 MeV. The result for high-energy photons can be explained by nucleon-nucleon bremsstrahlung if the initial flow of nucleons has a correlation to the reaction plane similar to the one observed for fast neutrons

  7. PET and Single-Photon Emission Computed Tomography in Brain Concussion.

    Science.gov (United States)

    Raji, Cyrus A; Henderson, Theodore A

    2018-02-01

    This article offers an overview of the application of PET and single photon emission computed tomography brain imaging to concussion, a type of mild traumatic brain injury and traumatic brain injury, in general. The article reviews the application of these neuronuclear imaging modalities in cross-sectional and longitudinal studies. Additionally, this article frames the current literature with an overview of the basic physics and radiation exposure risks of each modality. Copyright © 2017 Elsevier Inc. All rights reserved.

  8. Disturbance from Am-241 Photons of the Cellular Dose by Am-241 Alpha Emissions: Am-241 as an alternative source of alpha particles to radon daughters

    International Nuclear Information System (INIS)

    Lee, Ki-Man; Kim, Eun-Hee

    2015-01-01

    The Radiation Bioengineering Laboratory (RadBio Lab) at Seoul National University (SNU) has built an Am-241 alpha particle irradiator for study of cellular responses to radiation from radon daughters. The radon daughters of concern that cause internal exposure from inhalation of radon-contaminated air are Po-218, Po-214 and Po-210. In their alpha decay schemes, the yields of photon emissions are negligible. Unfortunately, Am-241, the source of alpha irradiator in RadBio Lab, emits photons at every alpha decay while transforming to Np-237 of long half-life. Employing Am-241 as the source simulating radon daughters, therefore, requires that photon emissions from Am-241 be specified in term of dose contribution. In this study, Monte Carlo calculations have been made to characterize dose contributions of Am-241 photon emissions. This study confirms that disturbance from Am-241 photon emissions of the cellular dose by Am-241 alpha emissions is negligible. Dose contamination fraction from photon emissions was 8.02 .. 10 -6 at 25 mm SSD at maximum. Also, note that LET in tissue-equivalent medium varies within about 20% for alpha particles at energies over 5 MeV

  9. Engineering photonic and plasmonic light emission enhancement

    Science.gov (United States)

    Lawrence, Nathaniel

    Semiconductor photonic devices are a rapidly maturing technology which currently occupy multi-billion dollar markets in the areas of LED lighting and optical data communication. LEDs currently demonstrate the highest luminous efficiency of any light source for general lighting. Long-haul optical data communication currently forms the backbone of the global communication network. Proper design of light management is required for photonic devices, which can increase the overall efficiency or add new device functionality. In this thesis, novel methods for the control of light propagation and confinement are developed for the use in integrated photonic devices. The first part of this work focuses on the engineering of field confinement within deep subwavelength plasmonic resonators for the enhancement of light-matter interaction. In this section, plasmonic ring nanocavities are shown to form gap plasmon modes confined to the dielectric region between two metal layers. The scattering properties, near-field enhancement and photonic density of states of nanocavity devices are studied using analytic theory and 3D finite difference time domain simulations. Plasmonic ring nanocavities are fabricated and characterized using photoluminescence intensity and decay rate measurements. A 25 times increase in the radiative decay rate of Er:Si02 is demonstrated in nanocavities where light is confined to volumes as small as 0.01( ln )3. The potential to achieve lasing, due to the enhancement of stimulated emission rate in ring nanocavities, is studied as a route to Si-compatible plasmon-enhanced nanolasers. The second part of this work focuses on the manipulation of light generated in planar semiconductor devices using arrays of dielectric nanopillars. In particular, aperiodic arrays of nanopillars are engineered for omnidirectional light extraction enhancement. Arrays of Er:SiNx, nanopillars are fabricated and a ten times increase in light extraction is experimentally demonstrated

  10. Silicon light-emitting diodes and lasers photon breeding devices using dressed photons

    CERN Document Server

    Ohtsu, Motoichi

    2016-01-01

    This book focuses on a novel phenomenon named photon breeding. It is applied to realizing light-emitting diodes and lasers made of indirect-transition-type silicon bulk crystals in which the light-emission principle is based on dressed photons. After presenting physical pictures of dressed photons and dressed-photon phonons, the principle of light emission by using dressed-photon phonons is reviewed. A novel phenomenon named photon breeding is also reviewed. Next, the fabrication and operation of light emitting diodes and lasers are described The role of coherent phonons in these devices is discussed. Finally, light-emitting diodes using other relevant crystals are described and other relevant devices are also reviewed.

  11. Novel scanning probe microscope instrumentation with applications in nanotechnology

    International Nuclear Information System (INIS)

    Humphry, M.J.

    2000-10-01

    A versatile scanning probe microscope controller has been constructed. Its suitability for the control of a range of different scanning probe microscope heads has been demonstrated. These include an ultra high vacuum scanning tunnelling microscope, with which atomic resolution images of Si surfaces was obtained, a custom-built atomic force microscope, and a custom-built photon emission scanning tunnelling microscope. The controller has been designed specifically to facilitate data acquisition during molecular manipulation experiments. Using the controller, the fullerene molecule C 60 has been successfully manipulated on Si(100)-2x1 surfaces and detailed data has been acquired during the manipulation process. Evidence for two distinct modes of manipulation have been observed. A repulsive mode with success rates up to 90% was found to occur with tunnel gap impedances below 2GΩ, while between 2GΩ and 8GΩ attractive manipulation events were observed, with a maximum success rate of ∼8%. It was also found that the step size between feedback updates had a significant effect on tip stability, and that dwell time of the STM tip at each data point had a critical effect on manipulation probability. A multi-function scanning probe microscope head has been developed capable of operation as a scanning tunnelling microscope and an atomic force microscope in vacuum and a magnetic field of 7T. The custom-built controller also presented here was used to control the head. A three-axis inertial sliding motor was developed for the head, capable of reproducible step sizes of <1000A. In addition, an optical fibre interferometer was constructed with a sensitivity of 0.2A/√Hz. Preliminary development of a magnetic resonance force microscope mode has also been performed, with initial results showing such a system to be feasible. (author)

  12. Dirac tensor with heavy photon

    Energy Technology Data Exchange (ETDEWEB)

    Bytev, V.V.; Kuraev, E.A. [Joint Institute of Nuclear Research, Moscow (Russian Federation). Bogoliubov Lab. of Theoretical Physics; Scherbakova, E.S. [Hamburg Univ. (Germany). 1. Inst. fuer Theoretische Physik

    2012-01-15

    For the large-angles hard photon emission by initial leptons in process of high energy annihilation of e{sup +}e{sup -} {yields} to hadrons the Dirac tensor is obtained, taking into account the lowest order radiative corrections. The case of large-angles emission of two hard photons by initial leptons is considered. This result is being completed by the kinematics case of collinear hard photons emission as well as soft virtual and real photons and can be used for construction of Monte-Carlo generators. (orig.)

  13. Relativistic quantum dynamics in strong fields: Photon emission from heavy, few-electron ions

    International Nuclear Information System (INIS)

    Fritzsche, S.; Stoehlker, T.

    2005-03-01

    Recent progress in the study of the photon emission from highly-charged heavy ions is reviewed. These investigations show that high-Z ions provide a unique tool for improving the understanding of the electron-electron and electron-photon interaction in the presence of strong fields. Apart from the bound-state transitions, which are accurately described in the framework of quantum electrodynamics, much information has been obtained also from the radiative capture of (quasi-) free electrons by high-Z ions. Many features in the observed spectra hereby confirm the inherently relativistic behavior of even the simplest compound quantum systems in nature. (orig.)

  14. Ultra-weak photon emission as a non-invasive tool for monitoring of oxidative processes in the epidermal cells of human skin: comparative study on the dorsal and the palm side of the hand.

    Science.gov (United States)

    Rastogi, Anshu; Pospísil, Pavel

    2010-08-01

    All living organisms emit spontaneous ultra-weak photon emission as a result of cellular metabolic processes. Exposure of living organisms to exogenous factors results in oxidative processes and enhancement in ultra-weak photon emission. Here, hydrogen peroxide (H(2)O(2)), as a strongly oxidizing molecule, was used to induce oxidative processes and enhance ultra-weak photon emission in human hand skin. The presented work intends to compare both spontaneous and peroxide-induced ultra-weak photon emission from the epidermal cells on the dorsal and the palm side of the hand. A highly sensitive photomultiplier tube and a charge-coupled device camera were used to detect ultra-weak photon emission from human hand skin. Spontaneous ultra-weak photon emission from the epidermal cells on the dorsal side of the hand was 4 counts/s. Topical application of 500 mM H(2)O(2) to the dorsal side of the hand caused enhancement in ultra-weak photon emission to 40 counts/s. Interestingly, both spontaneous and peroxide-induced ultra-weak photon emission from the epidermal cells on the palm side of the hand were observed to increase twice their values, i.e. 8 and 80 counts/s, respectively. Similarly, the two-dimensional image of ultra-weak photon emission observed after topical application of H(2)O(2) to human skin reveals that photon emission from the palm side exceeds the photon emission from the dorsal side of the hand. The results presented indicate that the ultra-weak photon emission originating from the epidermal cells on the dorsal and the palm side of the hand is related to the histological structure of the human hand skin. Ultra-weak photon emission is shown as a non-destructive technique for monitoring of oxidative processes in the epidermal cells of the human hand skin and as a diagnostic tool for skin diseases.

  15. Two-photon-induced hot-electron transfer to a single molecule in a scanning tunneling microscope

    International Nuclear Information System (INIS)

    Wu, S. W.; Ho, W.

    2010-01-01

    The junction of a scanning tunneling microscope (STM) operating in the tunneling regime was irradiated with femtosecond laser pulses. A photoexcited hot electron in the STM tip resonantly tunnels into an excited state of a single molecule on the surface, converting it from the neutral to the anion. The electron-transfer rate depends quadratically on the incident laser power, suggesting a two-photon excitation process. This nonlinear optical process is further confirmed by the polarization measurement. Spatial dependence of the electron-transfer rate exhibits atomic-scale variations. A two-pulse correlation experiment reveals the ultrafast dynamic nature of photoinduced charging process in the STM junction. Results from these experiments are important for understanding photoinduced interfacial charge transfer in many nanoscale inorganic-organic structures.

  16. Laser based imaging of time depending microscopic scenes with strong light emission

    Science.gov (United States)

    Hahlweg, Cornelius; Wilhelm, Eugen; Rothe, Hendrik

    2011-10-01

    Investigating volume scatterometry methods based on short range LIDAR devices for non-static objects we achieved interesting results aside the intended micro-LIDAR: the high speed camera recording of the illuminated scene of an exploding wire -intended for Doppler LIDAR tests - delivered a very effective method of observing details of objects with extremely strong light emission. As a side effect a schlieren movie is gathered without any special effort. The fact that microscopic features of short time processes with high emission and material flow might be imaged without endangering valuable equipment makes this technique at least as interesting as the intended one. So we decided to present our results - including latest video and photo material - instead of a more theoretical paper on our progress concerning the primary goal.

  17. Polychromatic photons

    DEFF Research Database (Denmark)

    Keller, Ole

    2002-01-01

    train quantum electrodynamics. A brief description of particle (photon) position operators is given, and it is shown that photons usually are only algebraically confined in an emission process. Finally, it is demonstrated that the profile of the birth domain of a radio-frequency photon emitted...

  18. Single photon emission computed tomography and oth selected computer topics

    International Nuclear Information System (INIS)

    Frey, G.D.

    1981-01-01

    This book, the proceedings of a meeting in January 1980, contains 21 papers. Thirteen are devoted to aspects of emission tomography, four to nuclear cardiology, and five to other topics. The initial set of papers consists of reviews of the single photon emission tomography process. These include transverse axial tomography using scintillation cameras and other devices, longitudinal section tomography, and pin-hole and slant-hole systems. These reviews are generally well done, but as might be expected, lack any coherence from paper to paper. The papers on nuclear cardiology include several of Fourier analysis in nuclear cardiology and one on shunt quantification. Other clinical papers are on quantifying Tc-99m glucoheptonate uptake in the brain and on iron-59 retention studies. A general criticism of the book is the poor quality of photographic reproductions

  19. Single-photon emission computed tomography in the clinical evaluation of dementia

    International Nuclear Information System (INIS)

    Jagust, W.J.; Reed, B.R.; Budinger, T.F.; Colina, M.

    1987-01-01

    Physiological imaging using positron emission tomography (PET) has been a useful tool in the investigation of dementia. In particular, patterns of cerebral glucose utilization appear to differentiate various types of dementia, with Alzheimer's disease (AD) demonstrating a propensity for hypometabolism to involve the temporoparietal cortex. Single-photon emission computed tomography (SPECT) using new tracers for the measurement of regional cerebral blood flow is a technique with potentially broader clinical availability than PET and thus may provide a practical method of routinely evaluating patients. The authors studied eight patients with AD, four healthy elderly controls, and one patient with multi-infarct dementia (MID) using the tracer 123 I-N-isopropyl-p-iodoamphetamine with SPECT

  20. Development of radioiodinated receptor ligands for cerebral single photon emission tomography

    International Nuclear Information System (INIS)

    Knapp, F.F. Jr.; McPherson, D.W.

    1992-01-01

    In the last decade the use of radiolabeled ligands for the imaging of cerebral receptors by emission computed tomography (ECT) has seen rapid growth. The opportunity to routinely perform cerebral single photon emission tomography (SPET) with iodine-123-labeled ligands depends on the availability of receptor ligands into which iodine can be introduced without decreasing the required high target receptor specificity. The use of iodine-123-labeled receptor-specific ligands also depends on the availability of high purity iodine-123 at reasonable costs and the necessary imaging instrumentation. In this paper, the development and current stage of evaluation of various iodine-123-labeled ligands for SPET imaging of dopaminergic, serotonergic and muscarinic acetylcholinergic receptor classes are discussed

  1. Single photon emission computed tomography of the liver

    International Nuclear Information System (INIS)

    Makler, P.T. Jr.

    1988-01-01

    Single photon emission computed tomography (SPECT) of the liver has been introduced in order to improve sensitivity and localization of space-occupying lesions. There have been numerous reports on the usefulness of the technique, as well as extensive analyses of its technical drawbacks. In general, SPECT provides a more accurate estimation of defect size than does conventional planar scintigraphy for cases in which one wishes to evaluate changes in lesion size due to therapy. The presence of a superimposed parenchymal disease, however, remains a major problem, which will only be resolved by a scanning technique that specifically detects the disease process of concern (hot spot imaging) rather than displacement of normal tissue (cold spot imaging)

  2. Brain receptor single-photon emission computer tomography with 123I Datscan in Parkinson's disease

    International Nuclear Information System (INIS)

    Minchev, D.; Peshev, N.; Kostadinova, I.; Grigorova, O.; Trindev, P.; Shotekov, P.

    2005-01-01

    Clinical aspects of Parkinson's disease are not enough for the early diagnosis of the disease. Positron emission tomography and the receptor single - photon emission tomography can be used for imaging functional integrity of nigrostriatal dopaminergic structures. 24 patient (17 men and 7 women) were investigated. 20 of them are with Parkinson's disease and 4 are with essential tremor. The radiopharmaceutical - 123I-Datscan (ioflupane, bind with 123I) represent a cocaine analogue with selective affinity to dopamine transporters, located in the dopaminergic nigrostriatal terminals in the striatum. Single - photon emission computer tomography was performed with SPECT gamma camera (ADAC, SH Epic detector). The scintigraphic study was made 3 to 6 hours after intravenous injection of the radiopharmaceutical - 123I- Datscan in dose 185 MBq. 120 frames are registered with duration of each one 22 seconds and gamma camera rotation 360. After generation of transversal slices we generated two composites pictures. The first composite picture image the striatum, the second - the occipital region. Two ratios were calculated representing the uptake of the radiopharmaceutical in the left and right striatum. Qualitative and quantitative criteria were elaborated for evaluating the scintigraphic patterns. Decreased, nonhomogeneous and asymmetric uptake of the radiopharmaceutical coupled with low quantitative parameters in range from 1.44 to 2.87 represents the characteristic scintigraphic pattern for Parkinson's disease with clear clinical picture. Homogenous with high intensity and symmetric uptake of the radiopharmaceutical in the striatum coupled with his clear frontier and with quantitative parameters up to 4.40 represent the scintigraphic pattern in two patients with essential tremor. Receptor single - photon emission computer tomography with 123I - Datscan represents an accurate nuclear-medicine method for precise diagnosis of Parkinson's disease and for its differentiation from

  3. Single-photon emission at a rate of 143 MHz from a deterministic quantum-dot microlens triggered by a mode-locked vertical-external-cavity surface-emitting laser

    Energy Technology Data Exchange (ETDEWEB)

    Schlehahn, A.; Gschrey, M.; Schnauber, P.; Schulze, J.-H.; Rodt, S.; Strittmatter, A.; Heindel, T., E-mail: tobias.heindel@tu-berlin.de; Reitzenstein, S. [Institut für Festkörperphysik, Technische Universität Berlin, Berlin 10623 (Germany); Gaafar, M.; Vaupel, M.; Stolz, W.; Rahimi-Iman, A.; Koch, M. [Department of Physics and Materials Science Center, Philipps-Universität Marburg, 35032 Marburg (Germany)

    2015-07-27

    We report on the realization of a quantum dot (QD) based single-photon source with a record-high single-photon emission rate. The quantum light source consists of an InGaAs QD which is deterministically integrated within a monolithic microlens with a distributed Bragg reflector as back-side mirror, which is triggered using the frequency-doubled emission of a mode-locked vertical-external-cavity surface-emitting laser (ML-VECSEL). The utilized compact and stable laser system allows us to excite the single-QD microlens at a wavelength of 508 nm with a pulse repetition rate close to 500 MHz at a pulse width of 4.2 ps. Probing the photon statistics of the emission from a single QD state at saturation, we demonstrate single-photon emission of the QD-microlens chip with g{sup (2)}(0) < 0.03 at a record-high single-photon flux of (143 ± 16) MHz collected by the first lens of the detection system. Our approach is fully compatible with resonant excitation schemes using wavelength tunable ML-VECSELs, which will optimize the quantum optical properties of the single-photon emission in terms of photon indistinguishability.

  4. Photon path distribution and optical responses of turbid media: theoretical analysis based on the microscopic Beer-Lambert law.

    Science.gov (United States)

    Tsuchiya, Y

    2001-08-01

    A concise theoretical treatment has been developed to describe the optical responses of a highly scattering inhomogeneous medium using functions of the photon path distribution (PPD). The treatment is based on the microscopic Beer-Lambert law and has been found to yield a complete set of optical responses by time- and frequency-domain measurements. The PPD is defined for possible photons having a total zigzag pathlength of l between the points of light input and detection. Such a distribution is independent of the absorption properties of the medium and can be uniquely determined for the medium under quantification. Therefore, the PPD can be calculated with an imaginary reference medium having the same optical properties as the medium under quantification except for the absence of absorption. One of the advantages of this method is that the optical responses, the total attenuation, the mean pathlength, etc are expressed by functions of the PPD and the absorption distribution.

  5. Direct photons in heavy-ion collisions

    Energy Technology Data Exchange (ETDEWEB)

    Baeuchle, Bjoern

    2010-12-13

    Direct photon emission from heavy-ion collisions has been calculated and compared to available experimental data. Three different models have been combined to extract direct photons from different environments in a heavy-ion collision: Thermal photons from partonic and hadronic matter have been extracted from relativistic, non-viscous 3+1-dimensional hydrodynamic calculations. Thermal and non-thermal photons from hadronic interactions have been calculated from relativistic transport theory. The impact of different physics assumptions about the thermalized matter has been studied. The models used for the determination of photons from both hydrodynamic and transport calculations have been elucidated and their numerical properties tested. The origin of direct photons, itemised by emission stage, emission time, channel and baryon number density, has been investigated for various systems, as have the transverse momentum spectra and elliptic flow patterns of direct photons. Taking into account the full (vacuum) spectral function of the rho-meson decreases the direct photon emission by approximately 10% at low photon transverse momentum. In all systems that have been considered -- heavy-ion collisions at E{sub lab}=35 AGeV and 158 AGeV, (s{sub NN}){sup 1/2}=62.4 GeV, 130 GeV and 200 GeV -- thermal emission from a system with partonic degrees of freedom is greatly enhanced over that from hadronic systems, while the difference between the direct photon yields from a viscous and a non-viscous hadronic system (transport vs. hydrodynamics) is found to be very small. Predictions for direct photon emission in central U+U-collisions at 35 AGeV have been made. (orig.)

  6. Direct photons in heavy-ion collisions

    International Nuclear Information System (INIS)

    Baeuchle, Bjoern

    2010-01-01

    Direct photon emission from heavy-ion collisions has been calculated and compared to available experimental data. Three different models have been combined to extract direct photons from different environments in a heavy-ion collision: Thermal photons from partonic and hadronic matter have been extracted from relativistic, non-viscous 3+1-dimensional hydrodynamic calculations. Thermal and non-thermal photons from hadronic interactions have been calculated from relativistic transport theory. The impact of different physics assumptions about the thermalized matter has been studied. The models used for the determination of photons from both hydrodynamic and transport calculations have been elucidated and their numerical properties tested. The origin of direct photons, itemised by emission stage, emission time, channel and baryon number density, has been investigated for various systems, as have the transverse momentum spectra and elliptic flow patterns of direct photons. Taking into account the full (vacuum) spectral function of the rho-meson decreases the direct photon emission by approximately 10% at low photon transverse momentum. In all systems that have been considered -- heavy-ion collisions at E lab =35 AGeV and 158 AGeV, (s NN ) 1/2 =62.4 GeV, 130 GeV and 200 GeV -- thermal emission from a system with partonic degrees of freedom is greatly enhanced over that from hadronic systems, while the difference between the direct photon yields from a viscous and a non-viscous hadronic system (transport vs. hydrodynamics) is found to be very small. Predictions for direct photon emission in central U+U-collisions at 35 AGeV have been made. (orig.)

  7. Single photon emission and quantum ring-cavity coupling in InAs/GaAs quantum rings

    International Nuclear Information System (INIS)

    Gallardo, E; Nowak, A K; Sanvitto, D; Meulen, H P van der; Calleja, J M; MartInez, L J; Prieto, I; Alija, A R; Granados, D; Taboada, A G; GarcIa, J M; Postigo, P A; Sarkar, D

    2010-01-01

    Different InAs/GaAs quantum rings embedded in a photonic crystal microcavity are studied by quantum correlation measurements. Single photon emission, with g (2) (0) values around 0.3, is demonstrated for a quantum ring not coupled to the microcavity. Characteristic rise-times are found to be longer for excitons than for biexcitons, resulting in the time asymmetry of the exciton-biexciton cross-correlation. No antibunching is observed in another quantum ring weakly coupled to the microcavity.

  8. High multi-photon visible upconversion emissions of Er3+ singly doped BiOCl microcrystals: A photon avalanche of Er3+ induced by 980 nm excitation

    International Nuclear Information System (INIS)

    Li, Yongjin; Song, Zhiguo; Li, Chen; Wan, Ronghua; Qiu, Jianbei; Yang, Zhengwen; Yin, Zhaoyi; Yang, Yong; Zhou, Dacheng; Wang, Qi

    2013-01-01

    Under 980 nm excitation, high multi-photon upconversion (UC) emission from the 2 H 11/2 / 4 S 3/2 (green) and 4 F 9/2 (red) levels of Er 3+ ions were observed from Er 3+ singly doped BiOCl microcrystals. These high-energy excited states were populated by a three to ten photon UC process conditionally, which depended on the pump power density and the Er 3+ ion doping concentration, characterizing as a hetero-looping enhanced energy transfer avalanche UC process. UC emission lifetime and Raman analysis suggest that the unusual UC phenomena are initiated by the new and intense phonon vibration modes of BiOCl lattices due to Er 3+ ions doping

  9. Comment on the effect of Cs on photon and secondary ion emission during sputtering

    International Nuclear Information System (INIS)

    Yu, M.L.

    1978-01-01

    The effect of Cs on photon and negative ion emission was discussed for the situations where the sputtered atom interacts either very weakly or very strongly with the target surface. The experimental data seem to favor the strong interaction case. 5 references

  10. A bioaccumulative cyclometalated platinum(II) complex with two-photon-induced emission for live cell imaging.

    Science.gov (United States)

    Koo, Chi-Kin; Wong, Ka-Leung; Man, Cornelia Wing-Yin; Lam, Yun-Wah; So, Leo King-Yan; Tam, Hoi-Lam; Tsao, Sai-Wah; Cheah, Kok-Wai; Lau, Kai-Chung; Yang, Yang-Yi; Chen, Jin-Can; Lam, Michael Hon-Wah

    2009-02-02

    The cyclometalated platinum(II) complex [Pt(L)Cl], where HL is a new cyclometalating ligand 2-phenyl-6-(1H-pyrazol-3-yl)pyridine containing C(phenyl), N(pyridyl), and N(pyrazolyl) donor moieties, was found to possess two-photon-induced luminescent properties. The two-photon-absorption cross section of the complex in N,N-dimethylformamide at room temperature was measured to be 20.8 GM. Upon two-photon excitation at 730 nm from a Ti:sapphire laser, bright-green emission was observed. Besides its two-photon-induced luminescent properties, [Pt(L)Cl] was able to be rapidly accumulated in live HeLa and NIH3T3 cells. The two-photon-induced luminescence of the complex was retained after live cell internalization and can be observed by two-photon confocal microscopy. Its bioaccumulation properties enabled time-lapse imaging of the internalization process of the dye into living cells. Cytotoxicity of [Pt(L)Cl] to both tested cell lines was low, according to MTT assays, even at loadings as high as 20 times the dose concentration for imaging for 6 h.

  11. Enhancement of Spontaneous Erbium Emission near the Photonic Band Edge of Distributed Bragg Reflectors Based on a-Si:H/a-SiOx:H

    International Nuclear Information System (INIS)

    Medvedev, A.V.; Feoktistov, N.A.; Pevtsov, A.B.; Golubev, V.G.

    2005-01-01

    Results obtained in an experimental study of spontaneous emission from erbium ions in a spectral range corresponding to the lower photonic band edge of distributed Bragg reflectors (1D photonic crystals) are presented. The photonic crystals were constituted of alternating quarter-wave a-Si:H and a-SiO x :H layers grown by PECVD. Erbium was introduced into the a-Si:H layers by magnetron sputtering of an erbium target in the course of structure growth. The change observed in the intensity of spontaneous emission is due to the nonmonotonic behavior of the density of optical modes near the photonic band edge

  12. Coupling of Ag Nanoparticle with Inverse Opal Photonic Crystals as a Novel Strategy for Upconversion Emission Enhancement of NaYF4: Yb(3+), Er(3+) Nanoparticles.

    Science.gov (United States)

    Shao, Bo; Yang, Zhengwen; Wang, Yida; Li, Jun; Yang, Jianzhi; Qiu, Jianbei; Song, Zhiguo

    2015-11-18

    Rare-earth-ion-doped upconversion (UC) nanoparticles have generated considerable interest because of their potential application in solar cells, biological labeling, therapeutics, and imaging. However, the applications of UC nanoparticles were still limited because of their low emission efficiency. Photonic crystals and noble metal nanoparticles are applied extensively to enhance the UC emission of rare earth ions. In the present work, a novel substrate consisting of inverse opal photonic crystals and Ag nanoparticles was prepared by the template-assisted method, which was used to enhance the UC emission of NaYF4: Yb(3+), Er(3+) nanoparticles. The red or green UC emissions of NaYF4: Yb(3+), Er(3+) nanoparticles were selectively enhanced on the inverse opal substrates because of the Bragg reflection of the photonic band gap. Additionally, the UC emission enhancement of NaYF4: Yb(3+), Er(3+) nanoparticles induced by the coupling of metal nanoparticle plasmons and photonic crystal effects was realized on the Ag nanoparticles included in the inverse opal substrate. The present results demonstrated that coupling of Ag nanoparticle with inverse opal photonic crystals provides a useful strategy to enhance UC emission of rare-earth-ion-doped nanoparticles.

  13. Photon emission from irradiated solids: Proceedings of the Werner Brandt workshop on penetration phenomena

    International Nuclear Information System (INIS)

    1986-11-01

    The workshop was concerned with photon emission from irradiated solids and the present record of the proceedings consists of material solicited from each participant. The results range from detailed and complete manuscripts to skeletal remnants of Vugraph transparencies. Individual papers have been cataloged separately

  14. Rate amplification of the two photon emission from para-hydrogen toward the neutrino mass measurement

    International Nuclear Information System (INIS)

    Masuda, Takahiko; Hara, Hideaki; Miyamoto, Yuki; Kuma, Susumu; Nakano, Itsuo; Ohae, Chiaki; Sasao, Noboru; Tanaka, Minoru; Uetake, Satoshi; Yoshimi, Akihiro; Yoshimura, Koji; Yoshimura, Motohiko

    2015-01-01

    We recently reported an experiment which focused on demonstrating the macro-coherent amplification mechanism. This mechanism, which was proposed for neutrino mass measurements, indicates that a multi-particle emission rate should be amplified by coherence in a suitable medium. Using a para-hydrogen molecule gas target and the adiabatic Raman excitation method, we observed that the two photon emission rate was amplified by a factor of more than 10 15 from the spontaneous emission rate. This paper briefly summarizes the previous experimental result and presents the current status and the future prospect

  15. Rate amplification of the two photon emission from para-hydrogen toward the neutrino mass measurement

    Energy Technology Data Exchange (ETDEWEB)

    Masuda, Takahiko, E-mail: masuda@okayama-u.ac.jp; Hara, Hideaki; Miyamoto, Yuki [Okayama University, Research Core for Extreme Quantum World (Japan); Kuma, Susumu [Atomic, Molecular and Optical Physics Laboratory, RIKEN (Japan); Nakano, Itsuo [Okayama University, Research Core for Extreme Quantum World (Japan); Ohae, Chiaki [University of Electro-Communications, Department of Engineering Science (Japan); Sasao, Noboru [Okayama University, Research Core for Extreme Quantum World (Japan); Tanaka, Minoru [Osaka University, Department of Physics (Japan); Uetake, Satoshi [Okayama University, Research Center of Quantum Universe (Japan); Yoshimi, Akihiro; Yoshimura, Koji [Okayama University, Research Core for Extreme Quantum World (Japan); Yoshimura, Motohiko [Okayama University, Research Center of Quantum Universe (Japan)

    2015-11-15

    We recently reported an experiment which focused on demonstrating the macro-coherent amplification mechanism. This mechanism, which was proposed for neutrino mass measurements, indicates that a multi-particle emission rate should be amplified by coherence in a suitable medium. Using a para-hydrogen molecule gas target and the adiabatic Raman excitation method, we observed that the two photon emission rate was amplified by a factor of more than 10{sup 15} from the spontaneous emission rate. This paper briefly summarizes the previous experimental result and presents the current status and the future prospect.

  16. Photon emission induced by brittle fracture of borosilicate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Shiota, Tadashi, E-mail: tshiota@ceram.titech.ac.jp [Department of Metallurgy and Ceramic Science, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550 (Japan); Sato, Yoshitaka [Department of Metallurgy and Ceramic Science, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550 (Japan); Kishi, Tetsuo [Department of Chemistry and Materials Science, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550 (Japan); Yasuda, Kouichi [Department of Metallurgy and Ceramic Science, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550 (Japan)

    2016-05-15

    Photon emission (PE) at wavelength ranges of 430–490 nm (B-PE), 500–600 nm (G-PE) and 610–680 nm (R-PE) caused by brittle fracture was simultaneously measured in the nanosecond-to-microsecond and millisecond time domains for two types of borosilicate glasses: Pyrex-type Tempax glass and BK7 glass. The results were compared to those for silica and soda lime glasses. The time dependence of the PE of Tempax glass was similar to that of silica glass, while the PE intensity was lower. Because Tempax glass contains both silica-rich and borate-rich amorphous phases, the PE must be mainly produced by the fracture of the silica-rich phase. Moreover, the proportion of B-PE of Tempax glass was higher than that of silica glass. This suggests that the measured B-PE might also include very weak PE caused by the fracture of the borate-rich phase. The PE time dependence of BK7 glass was similar to that of soda lime glass, which was different from the case for Tempax glass. The PE intensity of BK7 glass was slightly higher than that of soda lime glass, but much lower than that of Tempax glass. The result indicates that non-bridging oxygen in the glasses affects crack propagation behavior and reduces the PE. - Highlights: • Photon emission (PE) upon brittle fracture of borosilicate glasses was measured. • Pyrex-type Tempax and BK7 glasses showed different PE characteristics. • The rupture of Si–O bonds produces much stronger PE than that of B–O bonds. • Non-bridging oxygen in glass affects crack propagation behavior and reduces the PE.

  17. Analysis of photon-scanning tunneling microscope images of inhomogeneous samples: Determination of the local refractive index of channel waveguides

    International Nuclear Information System (INIS)

    Bourillot, E.; Fornel, F. de.; Goudonnet, J.P.

    1995-01-01

    Channel waveguides are imaged by a photon-scanning tunneling microscope (PSTM). The polarization of the light and its orientation with respect to the guide aids are shown to be very important parameters in the analysis of the images of such samples. We simulated image formation for the plane of incidence parallel to the axis of the guide. Our theoretical results are qualitatively in agreement with our measurements. These results show the ability of the PSTM to give information about the local refractive-index variations of a sample. 21 refs., 14 figs

  18. Two-color single-photon emission from InAs quantum dots: toward logic information management using quantum light.

    Science.gov (United States)

    Rivas, David; Muñoz-Matutano, Guillermo; Canet-Ferrer, Josep; García-Calzada, Raúl; Trevisi, Giovanna; Seravalli, Luca; Frigeri, Paola; Martínez-Pastor, Juan P

    2014-02-12

    In this work, we propose the use of the Hanbury-Brown and Twiss interferometric technique and a switchable two-color excitation method for evaluating the exciton and noncorrelated electron-hole dynamics associated with single photon emission from indium arsenide (InAs) self-assembled quantum dots (QDs). Using a microstate master equation model we demonstrate that our single QDs are described by nonlinear exciton dynamics. The simultaneous detection of two-color, single photon emission from InAs QDs using these nonlinear dynamics was used to design a NOT AND logic transference function. This computational functionality combines the advantages of working with light/photons as input/output device parameters (all-optical system) and that of a nanodevice (QD size of ∼ 20 nm) while also providing high optical sensitivity (ultralow optical power operational requirements). These system features represent an important and interesting step toward the development of new prototypes for the incoming quantum information technologies.

  19. Photonic crystal light source

    Science.gov (United States)

    Fleming, James G [Albuquerque, NM; Lin, Shawn-Yu [Albuquerque, NM; Bur, James A [Corrales, NM

    2004-07-27

    A light source is provided by a photonic crystal having an enhanced photonic density-of-states over a band of frequencies and wherein at least one of the dielectric materials of the photonic crystal has a complex dielectric constant, thereby producing enhanced light emission at the band of frequencies when the photonic crystal is heated. The dielectric material can be a metal, such as tungsten. The spectral properties of the light source can be easily tuned by modification of the photonic crystal structure and materials. The photonic crystal light source can be heated electrically or other heating means. The light source can further include additional photonic crystals that exhibit enhanced light emission at a different band of frequencies to provide for color mixing. The photonic crystal light source may have applications in optical telecommunications, information displays, energy conversion, sensors, and other optical applications.

  20. Ultrafast photon counting applied to resonant scanning STED microscopy.

    Science.gov (United States)

    Wu, Xundong; Toro, Ligia; Stefani, Enrico; Wu, Yong

    2015-01-01

    To take full advantage of fast resonant scanning in super-resolution stimulated emission depletion (STED) microscopy, we have developed an ultrafast photon counting system based on a multigiga sample per second analogue-to-digital conversion chip that delivers an unprecedented 450 MHz pixel clock (2.2 ns pixel dwell time in each scan). The system achieves a large field of view (∼50 × 50 μm) with fast scanning that reduces photobleaching, and advances the time-gated continuous wave STED technology to the usage of resonant scanning with hardware-based time-gating. The assembled system provides superb signal-to-noise ratio and highly linear quantification of light that result in superior image quality. Also, the system design allows great flexibility in processing photon signals to further improve the dynamic range. In conclusion, we have constructed a frontier photon counting image acquisition system with ultrafast readout rate, excellent counting linearity, and with the capacity of realizing resonant-scanning continuous wave STED microscopy with online time-gated detection. © 2014 The Authors Journal of Microscopy © 2014 Royal Microscopical Society.

  1. The 2-ID-B intermediate-energy scanning X-ray microscope at the APS

    International Nuclear Information System (INIS)

    McNulty, I.; Paterson, D.; Arko, J.; Erdmann, M.; Goetze, K.; Ilinski, P.; Mooney, T.; Vogt, S.; Xu, S.; Frigo, S.P.; Stampfl, A.P.J.; Wang, Y.

    2002-01-01

    The intermediate-energy scanning x-ray microscope at beamline 2-ID-B at the Advanced Photon Source is a dedicated instrument for materials and biological research. The microscope uses a zone plate lens to focus coherent 1-4 keV x-rays to a 60 nm focal spot of 10 9 photons/s onto the sample. It records simultaneous transmission and energy-resolved fluorescence images. We have used the microscope for nano-tomography of chips and micro-spectroscopy of cells. (authors)

  2. Amplified Photon Upconversion by Photonic Shell of Cholesteric Liquid Crystals.

    Science.gov (United States)

    Kang, Ji-Hwan; Kim, Shin-Hyun; Fernandez-Nieves, Alberto; Reichmanis, Elsa

    2017-04-26

    As an effective platform to exploit triplet-triplet-annihilation-based photon upconversion (TTA-UC), microcapsules composed of a fluidic UC core and photonic shell are microfluidically prepared using a triple emulsion as the template. The photonic shell consists of cholesteric liquid crystals (CLCs) with a periodic helical structure, exhibiting a photonic band gap. Combined with planar anchoring at the boundaries, the shell serves as a resonance cavity for TTA-UC emission and enables spectral tuning of the UC under low-power-density excitation. The CLC shell can be stabilized by introducing a polymerizable mesogen in the LC host. Because of the microcapsule spherical symmetry, spontaneous emission of the delayed fluorescence is omnidirectionally amplified at the edge of the stop band. These results demonstrate the range of opportunities provided by TTA-UC systems for the future design of low-threshold photonic devices.

  3. Recent Advances for High-Efficiency Sources of Single Photons Based on Photonic Nanowires

    DEFF Research Database (Denmark)

    Gerard, J. M.; Claudon, J.; Munsch, M.

    2012-01-01

    Photonic nanowires have recently been used to tailor the spontaneous emission of embedded quantum dots, and to develop record efficiency single-photon sources. We will present recent developments in this field mainly 1) the observation of a strong inhibition of the spontaneous emission of quantum...

  4. A bright single-photon source based on a photonic trumpet

    DEFF Research Database (Denmark)

    Munsch, Mathieu; Malik, Nitin S.; Bleuse, Joël

    Fiber-like photonic nanowires, which are optical waveguides made of a high refractive index material n, have recently emerged as non-resonant systems providing an efficient spontaneous emission (SE) control. When they embed a quantum emitter like a quantum dot (QD), they find application to the r......Fiber-like photonic nanowires, which are optical waveguides made of a high refractive index material n, have recently emerged as non-resonant systems providing an efficient spontaneous emission (SE) control. When they embed a quantum emitter like a quantum dot (QD), they find application...... to the realization of bright sources of quantum light and, reversibly, provide an efficient interface between propagating photons and the QD. For a wire diameter ∼ λ/n (λ is the operation wavelength), the fraction of QD SE coupled to the fundamental guided mode exceeds 90%. The collection of the photons can...... be brought close to unity with a proper engineering of the wire ends. In particular, a tapering of the top wire end is necessary to achieve a directive far-field emission pattern [1]. Recently, we have realized a single-photon source featuring a needle-like taper. The source efficiency, though record...

  5. Controlling light emission from single-photon sources using photonic nanowires

    DEFF Research Database (Denmark)

    Gregersen, Niels; Chen, Yuntian; Mørk, Jesper

    2012-01-01

    The photonic nanowire has recently emerged as an promising alternative to microcavity-based single-photon source designs. In this simple structure, a geometrical effect ensures a strong coupling between an embedded emitter and the optical mode of interest and a combination of tapers and mirrors a...

  6. Transition absorption as a mechanism of surface photoelectron emission from metals

    DEFF Research Database (Denmark)

    Zhukovsky, Sergei; Protsenko, Igor E.; Ikhsanov, Renat Sh

    2015-01-01

    Transition absorption of a photon by an electron passingthrough a boundary between two media with different permit-tivities is described both classically and quantum mechani-cally. Transition absorption is shown to make a substantialcontribution to photoelectron emission at a metal....../semicon-ductor interface in nanoplasmonic systems, and is put forth asa possible microscopic mechanism of the surface photoelec-tric effect in photodetectors and solar cells containing plas-monic nanoparticles....

  7. Infrared photonic bandgap materials and structures

    Science.gov (United States)

    Sundaram, S. K.; Keller, P. E.; Riley, B. J.; Martinez, J. E.; Johnson, B. R.; Allen, P. J.; Saraf, L. V.; Anheier, N. C., Jr.; Liau, F.

    2006-02-01

    Three-dimensional periodic dielectric structure can be described by band theory, analogous to electron waves in a crystal. Photonic band gap (PBG) structures were introduced in 1987. The PBG is an energy band in which optical modes, spontaneous emission, and zero-point fluctuations are all absent. It was first theoretically predicted that a three-dimensional photonic crystal could have a complete band gap. E. Yablonovitch built the first three-dimensional photonic crystal (Yablonovite) on microwave length scale, with a complete PBG. In nature, photonic crystals occur as semiprecious opal and the microscopic structures on the wings of some tropical butterflies, which are repeating structures (PBG structure/materials) that inhibit the propagation of some frequencies of light. Pacific Northwest National Laboratory (PNNL) has been developing tunable (between 3.5 and 16 μm) quantum cascade lasers (QCL), chalcogenides, and all other components for an integrated approach to chemical sensing. We have made significant progress in modeling and fabrication of infrared photonic band gap (PBG) materials and structures. We modeled several 2-D designs and defect configurations. Transmission spectra were computed by the Finite Difference Time Domain Method (with FullWAVE TM). The band gaps were computed by the Plane Wave Expansion Method (with BandSOLVE TM). The modeled designs and defects were compared and the best design was identified. On the experimental front, chalcogenide glasses were used as the starting materials. As IIS 3, a common chalcogenide, is an important infrared (IR) transparent material with a variety of potential applications such as IR sensors, waveguides, and photonic crystals. Wet-chemical lithography has been extended to PBG fabrication and challenges identified. An overview of results and challenges will be presented.

  8. Deterministic control of the emission from light sources in 1D nanoporous photonic crystals (Conference Presentation)

    Science.gov (United States)

    Galisteo-López, Juan F.

    2017-02-01

    Controlling the emission of a light source demands acting on its local photonic environment via the local density of states (LDOS). Approaches to exert such control on large scale samples, commonly relying on self-assembly methods, usually lack from a precise positioning of the emitter within the material. Alternatively expensive and time consuming techniques can be used to produce samples of small dimensions where a deterministic control on emitter position can be achieved. In this work we present a full solution process approach to fabricate photonic architectures containing nano-emitters which position can be controlled with nanometer precision over squared milimiter regions. By a combination of spin and dip coating we fabricate one-dimensional (1D) nanoporous photonic crystals, which potential in different fields such as photovoltaics or sensing has been previously reported, containing monolayers of luminescent polymeric nanospheres. We demonstrate how, by modifying the position of the emitters within the photonic crystal, their emission properties (photoluminescence intensity and angular distribution) can be deterministically modified. Further, the nano-emitters can be used as a probe to study the LDOS distribution within these systems with a spatial resolution of 25 nm (provided by the probe size) carrying out macroscopic measurements over squared milimiter regions. Routes to enhance light-matter interaction in this kind of systems by combining them with metallic surfaces are finally discussed.

  9. Measurement of Coherent Emission and Linear Polarization of Photons by Electrons in the Strong Fields of Aligned Crystals

    CERN Document Server

    Apyan, A.; Badelek, B.; Ballestrero, S.; Biino, C.; Birol, I.; Cenci, P.; Connell, S.H.; Eichblatt, S.; Fonseca, T.; Freund, A.; Gorini, B.; Groess, R.; Ispirian, K.; Ketel, T.J.; Kononets, Yu.V.; Lopez, A.; Mangiarotti, A.; van Rens, B.; Sellschop, J.P.F.; Shieh, M.; Sona, P.; Strakhovenko, V.; Uggerhoj, E.; Uggerhj, Ulrik Ingerslev; Unel, G.; Velasco, M.; Vilakazi, Z.Z.; Wessely, O.; Kononets, Yu.V.

    2004-01-01

    We present new results regarding the features of high energy photon emission by an electron beam of 178 GeV penetrating a 1.5 cm thick single Si crystal aligned at the Strings-Of-Strings (SOS) orientation. This concerns a special case of coherent bremsstrahlung where the electron interacts with the strong fields of successive atomic strings in a plane and for which the largest enhancement of the highest energy photons is expected. The polarization of the resulting photon beam was measured by the asymmetry of electron-positron pair production in an aligned diamond crystal analyzer. By the selection of a single pair the energy and the polarization of individual photons could be measured in an the environment of multiple photons produced in the radiator crystal. Photons in the high energy region show less than 20% linear polarization at the 90% confidence level.

  10. Characteristics of a single photon emission tomography system with a wide field gamma camera

    International Nuclear Information System (INIS)

    Mathonnat, F.; Soussaline, F.; Todd-Pokropek, A.E.; Kellershohn, C.

    1979-01-01

    This text summarizes a work study describing the imagery possibilities of a single photon emission tomography system composed of a conventional wide field gamma camera, connected to a computer. The encouraging results achieved on the various phantoms studied suggest a significant development of this technique in clinical work in Nuclear Medicine Departments [fr

  11. Left ventricular volume determination from single-photon emission computed tomography

    International Nuclear Information System (INIS)

    Bunker, S.R.; Hartshorne, M.F.; Schmidt, W.P.; Cawthon, M.A.; Karl, R.D. Jr.; Bauman, J.M.; Howard, W.H. III; Rubal, B.J.

    1985-01-01

    To compare the accuracy of single-photon emission computed tomography (SPECT) with that of contrast cineangiography in measuring left ventricular end-diastolic volume, 25 consecutive patients undergoing catheterizaiton for coronary artery or valvular heart disease were first evaluated scintigraphically. SPECT volume values showed a high degree of correlation with those determined by angiography with a standard error of the estimate of 23 ml. SPECT offers a highly accurate and essentially noninvasive method for measuring chamber volumes that is independent of geometric assumptions about ventricular configuration and chest wall attenuation and does not require blood sample counting

  12. Left ventricular volume determination from single-photon emission computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Bunker, S.R.; Hartshorne, M.F.; Schmidt, W.P.; Cawthon, M.A.; Karl, R.D. Jr.; Bauman, J.M.; Howard, W.H. III; Rubal, B.J.

    1985-02-01

    To compare the accuracy of single-photon emission computed tomography (SPECT) with that of contrast cineangiography in measuring left ventricular end-diastolic volume, 25 consecutive patients undergoing catheterizaiton for coronary artery or valvular heart disease were first evaluated scintigraphically. SPECT volume values showed a high degree of correlation with those determined by angiography with a standard error of the estimate of 23 ml. SPECT offers a highly accurate and essentially noninvasive method for measuring chamber volumes that is independent of geometric assumptions about ventricular configuration and chest wall attenuation and does not require blood sample counting.

  13. Two-photon stimulated emission and pulse amplification

    International Nuclear Information System (INIS)

    Yuen, H.P.

    1975-01-01

    Threshold conditions are given for the sustained operation of standing-wave and long-pulse traveling-wave two-photon lasers. Pulse shortening in long-pulse two-photon amplification, a behavior absent in the one-photon case, is also demonstrated analytically. (U.S.)

  14. Super-resolution from single photon emission: toward biological application

    Science.gov (United States)

    Moreva, E.; Traina, P.; Forneris, J.; Ditalia Tchernij, S.; Guarina, L.; Franchino, C.; Picollo, F.; Ruo Berchera, I.; Brida, G.; Degiovanni, I. P.; Carabelli, V.; Olivero, P.; Genovese, M.

    2017-08-01

    Properties of quantum light represent a tool for overcoming limits of classical optics. Several experiments have demonstrated this advantage ranging from quantum enhanced imaging to quantum illumination. In this work, experimental demonstration of quantum-enhanced resolution in confocal fluorescence microscopy will be presented. This is achieved by exploiting the non-classical photon statistics of fluorescence emission of single nitrogen-vacancy (NV) color centers in diamond. By developing a general model of super-resolution based on the direct sampling of the kth-order autocorrelation function of the photoluminescence signal, we show the possibility to resolve, in principle, arbitrarily close emitting centers. Finally, possible applications of NV-based fluorescent nanodiamonds in biosensing and future developments will be presented.

  15. Photonic devices prepared by embossing in PDMS

    Energy Technology Data Exchange (ETDEWEB)

    Jandura, D., E-mail: jandura@fyzika.uniza.sk; Pudis, D.; Berezina, S.

    2017-02-15

    Highlights: • Fabrication technology of photonic devices based on embossing in PDMS is presented. • Analysis of morphological properties of prepared devices in PDMS by CLSM and AFM. • Spectral characterization of PDMS ring resonator proved the resonator functionality. - Abstract: In this paper, we present useful technique for fabrication of novel photonic devices created in the polydimethylsiloxane (PDMS). We use combination of direct laser writing in thin photoresist layer with embossing process of liquid PDMS. We prepared ring resonator and Mach-Zehnder interferometer in PDMS. The shape of prepared PDMS photonic devices was analyzed by confocal laser microscope and atomic force microscope. Optical characterization of these devices reveals extinction ratios of up to 20 dB.

  16. Photon-Enhanced Thermionic Emission in Cesiated p-Type and n-Type Silicon

    DEFF Research Database (Denmark)

    Reck, Kasper; Dionigi, Fabio; Hansen, Ole

    2014-01-01

    electrons. Efficiencies above 60% have been predicted theoretically for high solar concentration systems. Silicon is an interesting absorber material for high efficiency PETE solar cells, partly due to its mechanical and thermal properties and partly due to its electrical properties, including a close......Photon-enhanced thermionic emission (PETE) is a relatively new concept for high efficiency solar cells that utilize not only the energy of electrons excited across the band gap by photons, as in conventional photovoltaic solar cells, but also the energy usual lost to thermalization of the excited...... to ideal band gap. The work function of silicon is, however, too high for practical PETE implementations. A well-known method for lowering the work function of silicon (and other materials) is to apply approximately a monolayer of cesium to the silicon surface. We present the first measurements of PETE...

  17. Imaging of the dopaminergic neurotransmission system using single-photon emission tomography and positron emission tomography in patients with parkinsonism

    International Nuclear Information System (INIS)

    Booij, J.; Tissingh, G.; Winogrodzka, A.; Royen, E.A. van

    1999-01-01

    Parkinsonism is a feature of a number of neurodegenerative diseases, including Parkinson's disease, multiple system atrophy and progressive supranuclear palsy. The results of post-mortem studies point to dysfunction of the dopaminergic neurotransmitter system in patients with parkinsonism. Nowadays, by using single-photon emission tomography (SPET) and positron emission tomography (PET) it is possible to visualise both the nigrostriatal dopaminergic neurons and the striatal dopamine D 2 receptors in vivo. Consequently, SPET and PET imaging of elements of the dopaminergic system can play an important role in the diagnosis of several parkinsonian syndromes. This review concentrates on findings of SPET and PET studies of the dopaminergic neurotransmitter system in various parkinsonian syndromes. (orig.)

  18. Spectroscopy of photonic band gaps in mesoporous one-dimensional photonic crystals based on aluminum oxide

    International Nuclear Information System (INIS)

    Gorelik, V.S.; Voinov, Yu.P.; Shchavlev, V.V.; Bi, Dongxue; Shang, Guo Liang; Fei, Guang Tao

    2017-01-01

    Mesoporous one-dimensional photonic crystals based on aluminum oxide have been synthesized by electrochemical etching method. Reflection spectra of the obtained mesoporous samples in a wide spectral range that covers several band gaps are presented. Microscopic parameters of photonic crystals are calculated and corresponding reflection spectra for the first six band gaps are presented.

  19. Time gated fluorescence lifetime imaging and micro-volume spectroscopy using two-photon excitation

    NARCIS (Netherlands)

    Sytsma, J.; Vroom, J.M.; de Grauw, C.J.; Gerritsen, H.C.

    A scanning microscope utilizing two-photon excitation in combination with fluorescence lifetime contrast is presented. The microscope makes use of a tunable femtosecond titanium:sapphire laser enabling the two-photon excitation of a broad range of fluorescent molecules, including UV probes.

  20. High multi-photon visible upconversion emissions of Er{sup 3+} singly doped BiOCl microcrystals: A photon avalanche of Er{sup 3+} induced by 980 nm excitation

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yongjin; Song, Zhiguo, E-mail: songzg@kmust.edu.cn; Li, Chen; Wan, Ronghua; Qiu, Jianbei; Yang, Zhengwen; Yin, Zhaoyi; Yang, Yong; Zhou, Dacheng; Wang, Qi [School of Materials Science and Engineering, Kunming University of Science and Technology, Kunming 650093 (China)

    2013-12-02

    Under 980 nm excitation, high multi-photon upconversion (UC) emission from the {sup 2}H{sub 11/2}/{sup 4}S{sub 3/2} (green) and {sup 4}F{sub 9/2} (red) levels of Er{sup 3+} ions were observed from Er{sup 3+} singly doped BiOCl microcrystals. These high-energy excited states were populated by a three to ten photon UC process conditionally, which depended on the pump power density and the Er{sup 3+} ion doping concentration, characterizing as a hetero-looping enhanced energy transfer avalanche UC process. UC emission lifetime and Raman analysis suggest that the unusual UC phenomena are initiated by the new and intense phonon vibration modes of BiOCl lattices due to Er{sup 3+} ions doping.

  1. Zero-phonon-line emission of single molecules for applications in quantum information processing

    Science.gov (United States)

    Kiraz, Alper; Ehrl, M.; Mustecaplioglu, O. E.; Hellerer, T.; Brauchle, C.; Zumbusch, A.

    2005-07-01

    A single photon source which generates transform limited single photons is highly desirable for applications in quantum optics. Transform limited emission guarantees the indistinguishability of the emitted single photons. This, in turn brings groundbreaking applications in linear optics quantum information processing within an experimental reach. Recently, self-assembled InAs quantum dots and trapped atoms have successfully been demonstrated as such sources for highly indistinguishable single photons. Here, we demonstrate that nearly transform limited zero-phonon-line (ZPL) emission from single molecules can be obtained by using vibronic excitation. Furthermore we report the results of coincidence detection experiments at the output of a Michelson-type interferometer. These experiments reveal Hong-Ou-Mandel correlations as a proof of the indistinguishability of the single photons emitted consecutively from a single molecule. Therefore, single molecules constitute an attractive alternative to single InAs quantum dots and trapped atoms for applications in linear optics quantum information processing. Experiments were performed with a home-built confocal microscope keeping the sample in a superfluid liquid Helium bath at 1.4K. We investigated terrylenediimide (TDI) molecules highly diluted in hexadecane (Shpol'skii matrix). A continuous wave single mode dye laser was used for excitation of vibronic transitions of individual molecules. From the integral fluorescence, the ZPL of single molecules was selected with a spectrally narrow interference filter. The ZPL emission was then sent to a scanning Fabry-Perot interferometer for linewidth measurements or a Michelson-type interferometer for coincidence detection.

  2. Single photon emission computerized tomography (SPECT)

    International Nuclear Information System (INIS)

    Ganatra, R.D.

    1992-01-01

    Tomography in nuclear medicine did not originate after the introduction of X-ray computerized tomography (CT). Even in the days of rectilinear scanner, tomography was attempted with multiple detector heads rotating around the patient, but the counts at each plane were never very high to obtain a satisfactory image. A high resolution focusing collimator can look at different depths but taking several slices in one projection was a time consuming process. Rectilinear scanners lose lot of counts in the collimator to look at one point, at on time, in one plane. It is true that attempts to do tomography with gamma camera really got a boost after the success of CT. By that time, algorithms for doing reconstruction of images also were highly refined and for advanced. Clinical application of SPECT has become widespread now, because of the development of suitable radiopharmaceuticals and improvement in instrumentation. The SPECT provides a direct measure of regional organ function and is performed with nuclides such as 123 I and 99 Tc m that emit a mono-image photon during their decay. SPECT is far less expensive than positron emission tomography

  3. Single photon emission computerized tomography (SPECT)

    Energy Technology Data Exchange (ETDEWEB)

    Ganatra, R D

    1993-12-31

    Tomography in nuclear medicine did not originate after the introduction of X-ray computerized tomography (CT). Even in the days of rectilinear scanner, tomography was attempted with multiple detector heads rotating around the patient, but the counts at each plane were never very high to obtain a satisfactory image. A high resolution focusing collimator can look at different depths but taking several slices in one projection was a time consuming process. Rectilinear scanners lose lot of counts in the collimator to look at one point, at on time, in one plane. It is true that attempts to do tomography with gamma camera really got a boost after the success of CT. By that time, algorithms for doing reconstruction of images also were highly refined and for advanced. Clinical application of SPECT has become widespread now, because of the development of suitable radiopharmaceuticals and improvement in instrumentation. The SPECT provides a direct measure of regional organ function and is performed with nuclides such as {sup 123}I and {sup 99}Tc{sup m} that emit a mono-image photon during their decay. SPECT is far less expensive than positron emission tomography

  4. Shifting wavelengths of ultraweak photon emissions from dying melanoma cells: their chemical enhancement and blocking are predicted by Cosic's theory of resonant recognition model for macromolecules.

    Science.gov (United States)

    Dotta, Blake T; Murugan, Nirosha J; Karbowski, Lukasz M; Lafrenie, Robert M; Persinger, Michael A

    2014-02-01

    During the first 24 h after removal from incubation, melanoma cells in culture displayed reliable increases in emissions of photons of specific wavelengths during discrete portions of this interval. Applications of specific filters revealed marked and protracted increases in infrared (950 nm) photons about 7 h after removal followed 3 h later by marked and protracted increases in near ultraviolet (370 nm) photon emissions. Specific wavelengths within the visible (400 to 800 nm) peaked 12 to 24 h later. Specific activators or inhibitors for specific wavelengths based upon Cosic's resonant recognition model elicited either enhancement or diminishment of photons at the specific wavelength as predicted. Inhibitors or activators predicted for other wavelengths, even within 10 nm, were less or not effective. There is now evidence for quantitative coupling between the wavelength of photon emissions and intrinsic cellular chemistry. The results are consistent with initial activation of signaling molecules associated with infrared followed about 3 h later by growth and protein-structural factors associated with ultraviolet. The greater-than-expected photon counts compared with raw measures through the various filters, which also function as reflective material to other photons, suggest that photons of different wavelengths might be self-stimulatory and could play a significant role in cell-to-cell communication.

  5. Degenerative dementia: nosological aspects and results of single photon emission computed tomography

    International Nuclear Information System (INIS)

    Dubois, B.; Habert, M.O.

    1999-01-01

    Ten years ago, the diagnosis discussion of a dementia case for the old patient was limited to two pathologies: the Alzheimer illness and the Pick illness. During these last years, the frame of these primary degenerative dementia has fallen into pieces. The different diseases and the results got with single photon emission computed tomography are discussed. for example: fronto-temporal dementia, primary progressive aphasia, progressive apraxia, visio-spatial dysfunction, dementia at Lewy's bodies, or cortico-basal degeneration. (N.C.)

  6. Bronchobiliary Fistula Localized by Cholescintigraphy with Single-Photon Emission Computed Tomography

    International Nuclear Information System (INIS)

    Artunduaga, Maddy; Patel, Niraj R.; Wendt, Julie A.; Guy, Elizabeth S.; Nachiappan, Arun C.

    2015-01-01

    Biliptysis is an important clinical feature to recognize as it is associated with bronchobiliary fistula, a rare entity. Bronchobiliary fistulas have been diagnosed with planar cholescintigraphy. However, cholescintigraphy with single-photon emission computed tomography (SPECT) can better spatially localize a bronchobiliary fistula as compared to planar cholescintigraphy alone, and is useful for preoperative planning if surgical treatment is required. Here, we present the case of a 23-year-old male who developed a bronchobiliary fistula in the setting of posttraumatic and postsurgical infection, which was diagnosed and localized by cholescintigraphy with SPECT

  7. Whispering gallery mode emission from a composite system of J-aggregates and photonic microcavity

    Energy Technology Data Exchange (ETDEWEB)

    Melnikau, Dzmitry; Savateeva, Diana [Centro de Física de Materiales (MPC, CSIC-UPV/EHU) and Donostia International Physics Center (DIPC), Po Manuel de Lardizabal 5, Donostia, San Sebastian 20018 (Spain); Rusakov, Konstantin I. [Department of Physics, Brest State Technical University, Brest 224017 (Belarus); Rakovich, Yury P., E-mail: Yury.Rakovich@ehu.es [Centro de Física de Materiales (MPC, CSIC-UPV/EHU) and Donostia International Physics Center (DIPC), Po Manuel de Lardizabal 5, Donostia, San Sebastian 20018 (Spain); IKERBASQUE, Basque Foundation for Science, Bilbao (Spain)

    2014-01-15

    We report on development and characterization of Whispering Gallery Modes spherical microcavities integrated with organic dye molecules in a J-aggregate state. The microcavities are studied using micro-photoluminescence spectroscopy, and fluorescence lifetime imaging confocal microscopy. Directional emission of light from the microcavity is also experimentally demonstrated and attributed to the photonic jets generated in the microsphere. -- Highlights: • Report on the development and characterization of hybrid system consisting of thin shell of J-aggregates and spherical Whispering Gallery Mode microcavity. • An investigation of spontaneous emission rate in the shell of J-aggregates integrated with a Whispering Gallery Mode cavity. • Demonstration of directional emission from Whispering Gallery Mode cavity with J-aggregates which is highly desirable functionality for both micro- and nano-scale cavities.

  8. Determining the phonon energy of highly oriented pyrolytic graphite by scanning tunneling microscope light emission spectroscopy

    Science.gov (United States)

    Uehara, Yoichi; Michimata, Junichi; Watanabe, Shota; Katano, Satoshi; Inaoka, Takeshi

    2018-03-01

    We have investigated the scanning tunneling microscope (STM) light emission spectra of isolated single Ag nanoparticles lying on highly oriented pyrolytic graphite (HOPG). The STM light emission spectra exhibited two types of spectral structures (step-like and periodic). Comparisons of the observed structures and theoretical predictions indicate that the phonon energy of the ZO mode of HOPG [M. Mohr et al., Phys. Rev. B 76, 035439 (2007)] can be determined from the energy difference between the cutoff of STM light emission and the step in the former structure, and from the period of the latter structure. Since the role of the Ag nanoparticles does not depend on the substrate materials, this method will enable the phonon energies of various materials to be measured by STM light emission spectroscopy. The spatial resolution is comparable to the lateral size of the individual Ag nanoparticles (that is, a few nm).

  9. Hybrid Single Photon Emission Computed Tomography/Computed Tomography Sulphur Colloid Scintigraphy in Focal Nodular Hyperplasia

    International Nuclear Information System (INIS)

    Bhoil, Amit; Gayana, Shankramurthy; Sood, Ashwani; Bhattacharya, Anish; Mittal, Bhagwant Rai

    2013-01-01

    It is important to differentiate focal nodular hyperplasia (FNH), a benign condition of liver most commonly affecting women, from other neoplasm such as hepatic adenoma and metastasis. The functional reticuloendothelial features of FNH can be demonstrated by scintigraphy. We present a case of breast cancer in whom fluorodeoxyglucose positron emission tomography/computerized tomography (CT) showed a homogenous hyperdense lesion in liver, which on Tc99m sulfur colloid single-photon emission computed tomography/CT was found to have increased focal tracer uptake suggestive of FNH

  10. Evaluation of scintillators and semiconductor detectors to image three-photon positron annihilation for positron emission tomography

    International Nuclear Information System (INIS)

    Abuelhia, E.; Spyrou, N.M.; Kacperski, K.; College University, Middlesex Hospital, London

    2008-01-01

    Positron emission tomography (PET) is rapidly becoming the main nuclear imaging modality of the present century. The future of PET instrumentation relies on semiconductor detectors because of their excellent characteristics. Three-photon positron annihilation has been recently investigated as a novel imaging modality, which demands the crucial high energy resolution of semiconductor detector. In this work the evaluation of the NaI(Tl) scintillator and HPGe and CdZTe semiconductor detectors, to construct a simple three-photon positron annihilation scanner has been explored. The effect of detector and scanner size on spatial resolution (FWHM) is discussed. The characteristics: energy resolution versus count rate and point-spread function of the three-photon positron annihilation image profile from triple coincidence measurements were investigated. (author)

  11. Single photon emission computed tomography in AIDS dementia complex

    International Nuclear Information System (INIS)

    Pohl, P.; Vogl, G.; Fill, H.; Roessler, H.Z.; Zangerle, R.; Gerstenbrand, F.

    1988-01-01

    Single photon emission computed tomography (SPECT) studies were performed in AIDS dementia complex using IMP in 12 patients (and HM-PAO in four of these same patients). In all patients, SPECT revealed either multiple or focal uptake defects, the latter corresponding with focal signs or symptoms in all but one case. Computerized tomography showed a diffuse cerebral atrophy in eight of 12 patients, magnetic resonance imaging exhibited changes like atrophy and/or leukoencephalopathy in two of five cases. Our data indicate that both disturbance of cerebral amine metabolism and alteration of local perfusion share in the pathogenesis of AIDS dementia complex. SPECT is an important aid in the diagnosis of AIDS dementia complex and contributes to the understanding of the pathophysiological mechanisms of this disorder

  12. Single photon emission computed tomography in children with idiopathic seizures

    International Nuclear Information System (INIS)

    Hara, Masafumi; Takahashi, Mutsumasa; Kojima, Akihiro; Shimomura, Osamu; Kinoshita, Rumi; Tomiguchi, Seiji; Taku, Keiichi; Miike, Teruhisa

    1991-01-01

    Single photon emission computed tomography (SPECT) with N-isoprophyl-p [ 123 I]-iodoamphetamine (IMP), X-ray computed tomography (X-CT), and magnetic resonance imaging (MRI) were performed in 20 children with idiopathic seizures. In children with idiopathic seizures, SPECT could detect the abnormal sites at the highest rate (45%) compared with CT (10%) and MRI (12%), but the abnormal sites on SPECT correlated poorly with the foci on electroencephalograph (EEG). Idiopathic epilepsy with hypoperfusion on SPECT was refractory to treatment and was frequently associated with mental and/or developmental retardation. Perfusion defects on SPECT scans probably affect the development and maturation of the brain in children. (author)

  13. Quantum photonics hybrid integration platform

    Energy Technology Data Exchange (ETDEWEB)

    Murray, E.; Floether, F. F. [Cambridge Research Laboratory, Toshiba Research Europe Limited, 208 Science Park, Milton Road, Cambridge CB4 0GZ (United Kingdom); Cavendish Laboratory, University of Cambridge, J.J. Thomson Avenue, Cambridge CB3 0HE (United Kingdom); Ellis, D. J. P.; Meany, T.; Bennett, A. J., E-mail: anthony.bennet@crl.toshiba.co.uk; Shields, A. J. [Cambridge Research Laboratory, Toshiba Research Europe Limited, 208 Science Park, Milton Road, Cambridge CB4 0GZ (United Kingdom); Lee, J. P. [Cambridge Research Laboratory, Toshiba Research Europe Limited, 208 Science Park, Milton Road, Cambridge CB4 0GZ (United Kingdom); Engineering Department, University of Cambridge, 9 J. J. Thomson Avenue, Cambridge CB3 0FA (United Kingdom); Griffiths, J. P.; Jones, G. A. C.; Farrer, I.; Ritchie, D. A. [Cavendish Laboratory, University of Cambridge, J.J. Thomson Avenue, Cambridge CB3 0HE (United Kingdom)

    2015-10-26

    Fundamental to integrated photonic quantum computing is an on-chip method for routing and modulating quantum light emission. We demonstrate a hybrid integration platform consisting of arbitrarily designed waveguide circuits and single-photon sources. InAs quantum dots (QD) embedded in GaAs are bonded to a SiON waveguide chip such that the QD emission is coupled to the waveguide mode. The waveguides are SiON core embedded in a SiO{sub 2} cladding. A tuneable Mach Zehnder interferometer (MZI) modulates the emission between two output ports and can act as a path-encoded qubit preparation device. The single-photon nature of the emission was verified using the on-chip MZI as a beamsplitter in a Hanbury Brown and Twiss measurement.

  14. A comparative study of attenuation correction algorithms in single photon emission computed tomography (SPECT)

    International Nuclear Information System (INIS)

    Murase, Kenya; Itoh, Hisao; Mogami, Hiroshi; Ishine, Masashiro; Kawamura, Masashi; Iio, Atsushi; Hamamoto, Ken

    1987-01-01

    A computer based simulation method was developed to assess the relative effectiveness and availability of various attenuation compensation algorithms in single photon emission computed tomography (SPECT). The effect of the nonuniformity of attenuation coefficient distribution in the body, the errors in determining a body contour and the statistical noise on reconstruction accuracy and the computation time in using the algorithms were studied. The algorithms were classified into three groups: precorrection, post correction and iterative correction methods. Furthermore, a hybrid method was devised by combining several methods. This study will be useful for understanding the characteristics limitations and strengths of the algorithms and searching for a practical correction method for photon attenuation in SPECT. (orig.)

  15. Effect of atomic initial phase difference on spontaneous emission of an atom embedded in photonic crystal

    International Nuclear Information System (INIS)

    Bing, Zhang; Xiu-Dong, Sun; Xiang-Qian, Jiang

    2010-01-01

    We investigate the effect of initial phase difference between the two excited states of a V-type three-level atom on its steady state behaviour of spontaneous emission. A modified density of modes is introduced to calculate the spontaneous emission spectra in photonic crystal. Spectra in free space are also shown to compare with that in photonic crystal with different relative positions of the excited levels from upper band-edge frequency. It is found that the initial phase difference plays an important role in the quantum interference property between the two decay channels. For a zero initial phase, destructive property is presented in the spectra. With the increase of initial phase difference, quantum interference between the two decay channels from upper levels to ground level turns to be constructive. Furthermore, we give an interpretation for the property of these spectra. (atomic and molecular physics)

  16. Silicon nanocrystal-based photonic crystal slabs with broadband and efficient directional light emission

    Czech Academy of Sciences Publication Activity Database

    Ondič, Lukáš; Varga, Marián; Pelant, Ivan; Valenta, J.; Kromka, Alexander; Elliman, R. G.

    2017-01-01

    Roč. 7, č. 1 (2017), s. 1-8, č. článku 5763. ISSN 2045-2322 R&D Projects: GA ČR GJ16-09692Y; GA MŠk(CZ) LD15003 Institutional support: RVO:68378271 Keywords : photonic crystal slab * silicon nanocrystals * light emission Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 4.259, year: 2016

  17. High-efficiency AlxGa1-xAs/GaAs cathode for photon-enhanced thermionic emission solar energy converters

    Science.gov (United States)

    Feng, Cheng; Zhang, Yijun; Qian, Yunsheng; Wang, Ziheng; Liu, Jian; Chang, Benkang; Shi, Feng; Jiao, Gangcheng

    2018-04-01

    A theoretical emission model for AlxGa1-xAs/GaAs cathode with complex structure based on photon-enhanced thermionic emission is developed by utilizing one-dimensional steady-state continuity equations. The cathode structure comprises a graded-composition AlxGa1-xAs window layer and an exponential-doping GaAs absorber layer. In the deduced model, the physical properties changing with the Al composition are taken into consideration. Simulated current-voltage characteristics are presented and some important factors affecting the conversion efficiency are also illustrated. Compared with the graded-composition and uniform-doping cathode structure, and the uniform-composition and uniform-doping cathode structure, the graded-composition and exponential-doping cathode structure can effectively improve the conversion efficiency, which is ascribed to the twofold built-in electric fields. More strikingly, this graded bandgap structure is especially suitable for photon-enhanced thermionic emission devices since a higher conversion efficiency can be achieved at a lower temperature.

  18. Optical quantitation of absorbers in variously shaped turbid media based on the microscopic Beer-Lambert law. A new approach to optical computerized tomography.

    Science.gov (United States)

    Tsuchiya, Y; Urakami, T

    1998-02-09

    To determine the concentrations of an absorber in variously shaped turbid media such as human tissue, we propose analytical expressions for diffuse re-emission in time and frequency domains, based on the microscopic Beer-Lambert law that holds true when we trace a zigzag photon path in the medium. Our expressions are implicit for the scattering properties, the volume shape, and the source-detector separation. We show that three observables are sufficient to determine the changes in the concentration and the absolute concentrations of an absorber in scattering media as long as the scattering property remains constant. The three observables are: the re-emission, the mean pathlength or group delay, and the extinction coefficient of the absorber. We also show that our equations can be extended to describe photon migration in nonuniform media. The validity of the predictions is confirmed by measuring a tissue-like phantom.

  19. The National Ignition Facility modular Kirkpatrick-Baez microscope

    Energy Technology Data Exchange (ETDEWEB)

    Pickworth, L. A., E-mail: pickworth1@llnl.gov; Ayers, J.; Bell, P.; Brejnholt, N. F.; Buscho, J. G.; Bradley, D.; Decker, T.; Hau-Riege, S.; McCarville, T.; Pardini, T.; Vogel, J.; Walton, C. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Kilkenny, J. [General Atomics, San Diego, California 92121 (United States)

    2016-11-15

    Current two-dimensional X-ray imaging at the National Ignition Facility (NIF) uses time resolved pinhole cameras with ∼10-25 μm pinholes. This method has limitations in the smallest resolvable features that can be imaged with reasonable photon statistics for inertial confinement fusion (ICF) applications. ICF sources have a broadband self-emission spectrum that causes the pinhole images obtained, through thin foil filters, to contain a similarly broadband spectrum complicating the interpretation of structure in the source. In order to study phenomena on the scale of ∼5 μm, such as dopant mix in the ICF capsule, a narrow energy band, higher spatial resolution microscope system with improved signal/noise has been developed using X-ray optics. Utilizing grazing incidence mirrors in a Kirkpatrick-Baez microscope (KBM) configuration [P. Kirkpatrick and A. V. Baez, J. Opt. Soc. Am. 38, 766–774 (1948)], an X-ray microscope has been designed and fielded on NIF with four imaging channels. The KBM has ∼12 × magnification, <8 μm resolution, and higher throughput in comparison to similar pinhole systems. The first KBM mirrors are coated with a multilayer mirror to allow a “narrow band” energy response at 10.2 keV with ΔE ∼ 3 keV. By adjusting the mirror coating only, the energy response can be matched to the future experimental requirements. Several mirror packs have been commissioned and are interchangeable in the diagnostic snout.

  20. Single-photon emission associated with double electron capture in F9+ + C collisions

    CERN Document Server

    Elkafrawy, Tamer; Tanis, John A; Warczak, Andrzej

    2016-01-01

    Radiative double electron capture (RDEC), the one-step process occurring in ion-atom collisions, has been investigated for bare fluorine ions colliding with carbon. RDEC is completed when two target electrons are captured to a bound state of a projectile simultaneously with the emission of a single photon. This work is a follow-up to our earlier measurement of RDEC for bare oxygen projectiles, thus providing a recipient system free of electron-related Coulomb fields in both cases and allowing for the comparison between the two collision systems as well as with available theoretical studies. The most significant mechanisms of x-ray emission that may contribute to the RDEC energy region as background processes are also addressed.

  1. Tunneling-Electron-Induced Light Emission from Single Gold Nanoclusters.

    Science.gov (United States)

    Yu, Arthur; Li, Shaowei; Czap, Gregory; Ho, W

    2016-09-14

    The coupling of tunneling electrons with the tip-nanocluster-substrate junction plasmon was investigated by monitoring light emission in a scanning tunneling microscope (STM). Gold atoms were evaporated onto the ∼5 Å thick Al2O3 thin film grown on the NiAl (110) surface where they formed nanoclusters 3-7 nm wide. Scanning tunneling spectroscopy (STS) of these nanoclusters revealed quantum-confined electronic states. Spatially resolved photon imaging showed localized emission hot spots. Size dependent study and light emission from nanocluster dimers further support the viewpoint that coupling of tunneling electrons to the junction plasmon is the main radiative mechanism. These results showed the potential of the STM to reveal the electronic and optical properties of nanoscale metallic systems in the confined geometry of the tunnel junction.

  2. Exploring the environmental transmission electron microscope

    DEFF Research Database (Denmark)

    Wagner, Jakob B.; Cavalca, Filippo; Damsgaard, Christian D.

    2012-01-01

    of the opportunities that the environmental TEM (ETEM) offers when combined with other in situ techniques will be explored, directly in the microscope, by combining electron-based and photon-based techniques and phenomena. In addition, application of adjacent setups using sophisticated transfer methods...

  3. Comparison between laser terahertz emission microscope and conventional methods for analysis of polycrystalline silicon solar cell

    Directory of Open Access Journals (Sweden)

    Hidetoshi Nakanishi

    2015-11-01

    Full Text Available A laser terahertz emission microscope (LTEM can be used for noncontact inspection to detect the waveforms of photoinduced terahertz emissions from material devices. In this study, we experimentally compared the performance of LTEM with conventional analysis methods, e.g., electroluminescence (EL, photoluminescence (PL, and laser beam induced current (LBIC, as an inspection method for solar cells. The results showed that LTEM was more sensitive to the characteristics of the depletion layer of the polycrystalline solar cell compared with EL, PL, and LBIC and that it could be used as a complementary tool to the conventional analysis methods for a solar cell.

  4. Development of a high energy resolution magnetic bolometer for the determination of photon emission intensities by gamma-ray spectrometry

    International Nuclear Information System (INIS)

    Rodrigues, M.

    2007-12-01

    In this research thesis, a first chapter describes the metrological difficulties for the determination of radionuclide photon emission intensities. Then, it discusses the understanding and the required tools for the computing of a magnetic bolometer signal with respect to the different operation parameters and to the sensor geometry. The author describes the implementation of the experimental device and its validation with a first sensor. The new sensor is then optimised for the measurement of photon emission intensities with a good efficiency and a theoretical energy resolution less than 100 eV up to 200 keV. The sensor's detection efficiency and operation have been characterized with a 133 Ba source. The author finally presents the obtained results

  5. Interictal "patchy" regional cerebral blood flow patterns in migraine patients. A single photon emission computerized tomographic study

    DEFF Research Database (Denmark)

    Friberg, L; Olesen, J; Iversen, Helle Klingenberg

    1994-01-01

    In 92 migraine patients and 44 healthy control subjects we recorded regional cerebral blood flow (rCBF) with single photon emission computerized tomography and (133) Xe inhalation or with i.v. (99m) Tc-HMPAO. Migraine patients were studied interictally. A quantitated analysis of right-left asymme......In 92 migraine patients and 44 healthy control subjects we recorded regional cerebral blood flow (rCBF) with single photon emission computerized tomography and (133) Xe inhalation or with i.v. (99m) Tc-HMPAO. Migraine patients were studied interictally. A quantitated analysis of right...... rCBF images is insufficient to pick up abnormalities; (2) almost 50% of the migraine sufferers had abnormal rCBF/asymmetries. However, these are discrete compared with those typically seen during the aura phase of a migraine attack. One explanation to the patchy rCBF patterns might...

  6. Automatic quantification of mitochondrial fragmentation from two-photon microscope images of mouse brain tissue.

    Science.gov (United States)

    Lihavainen, E; Kislin, M; Toptunov, D; Khiroug, L; Ribeiro, A S

    2015-12-01

    The morphology of mitochondria can inform about their functional state and, thus, about cell vitality. For example, fragmentation of the mitochondrial network is associated with many diseases. Recent advances in neuronal imaging have enabled the observation of mitochondria in live brains for long periods of time, enabling the study of their dynamics in animal models of diseases. To aid these studies, we developed an automatic method, based on supervised learning, for quantifying the degree of mitochondrial fragmentation in tissue images acquired via two-photon microscopy from transgenic mice, which exclusively express Enhanced cyan fluorescent protein (ECFP) under Thy1 promoter, targeted to the mitochondrial matrix in subpopulations of neurons. We tested the method on images prior to and after cardiac arrest, and found it to be sensitive to significant changes in mitochondrial morphology because of the arrest. We conclude that the method is useful in detecting morphological abnormalities in mitochondria and, likely, in other subcellular structures as well. © 2015 The Authors Journal of Microscopy © 2015 Royal Microscopical Society.

  7. Tuning Ag29 nanocluster light emission from red to blue with one and two-photon excitation.

    Science.gov (United States)

    Russier-Antoine, Isabelle; Bertorelle, Franck; Hamouda, Ramzi; Rayane, Driss; Dugourd, Philippe; Sanader, Željka; Bonačić-Koutecký, Vlasta; Brevet, Pierre-François; Antoine, Rodolphe

    2016-02-07

    We demonstrate that the tuning of the light emission from red to blue in dihydrolipoic acid (DHLA) capped Ag29 nanoclusters can be trigged with one and two photon excitations. The cluster stoichiometry was determined with mass spectrometry and found to be Ag29(DHLA)12. In a detailed optical investigation, we show that these silver nanoclusters exhibit a strong red photoluminescence visible to the naked eye and characterized by a quantum yield of nearly ∼2% upon one-photon excitation. In the nonlinear optical (NLO) study of the properties of the clusters, the two-photon excited fluorescence spectra were recorded and their first hyperpolarizability obtained. The two-photon absorption cross-section at ∼800 nm for Ag29(DHLA)12 is higher than 10(4) GM and the hyperpolarizability is 106 × 10(-30) esu at the same excitation wavelength. The two-photon excited fluorescence spectrum appears strongly blue-shifted as compared to the one-photon excited spectrum, displaying a broad band between 400 and 700 nm. The density functional theory (DFT) provides insight into the structural and electronic properties of Ag29(DHLA)12 as well as into interplay between metallic subunit or core and ligands which is responsible for unique optical properties.

  8. Enhanced light emission in photonic crystal nanocavities with Erbium-doped silicon nanocrystals

    International Nuclear Information System (INIS)

    Makarova, Maria; Sih, Vanessa; Vuckovic, Jelena; Warga, Joe; Li Rui; Dal Negro, Luca

    2008-01-01

    Photonic crystal nanocavities are fabricated in silicon membranes covered by thermally annealed silicon-rich nitride films with Erbium-doped silicon nanocrystals. Silicon nitride films were deposited by sputtering on top of silicon on insulator wafers. The nanocavities were carefully designed in order to enhance emission from the nanocrystal sensitized Erbium at the 1540 nm wavelength. Experimentally measured quality factors of ∼6000 were found to be consistent theoretical predictions. The Purcell factor of 1.4 was estimated from the observed 20-fold enhancement of Erbium luminescence

  9. Emissions of Photonic Crystal Waveguides with Discretely Modulated Surfaces

    International Nuclear Information System (INIS)

    Dong-Hua, Tang; Li-Xue, Chen; Yan, Liu; Xiu-Dong, Sun; Wei-Qiang, Ding

    2009-01-01

    Transmission properties of photonic crystal (PC) waveguides with discretely modulated exit surfaces are investigated numerically using the unite-difference time-domain (FDTD) method. Unlike the case of periodically modulated surfaces, where the transmission beam tends to be a single and directional beam, when the exit surfaces are modulated only at several discrete points, the emission power tends to split into multiple and directional beams. We explain this phenomenon using a multiple point source interference model. Based on these results, we propose a 1-to-N beam splitter, and numerically realized high efficiency coupling between a PC sub-wavelength waveguide and three traditional dielectric waveguides with a total efficiency larger than 92%. This simple, easy fabrication, and controllable mechanism may find more potential applications in integrated optical circuits. (fundamental areas of phenomenology(including applications))

  10. Nearly Blinking-Free, High-Purity Single-Photon Emission by Colloidal InP/ZnSe Quantum Dots.

    Science.gov (United States)

    Chandrasekaran, Vigneshwaran; Tessier, Mickaël D; Dupont, Dorian; Geiregat, Pieter; Hens, Zeger; Brainis, Edouard

    2017-10-11

    Colloidal core/shell InP/ZnSe quantum dots (QDs), recently produced using an improved synthesis method, have a great potential in life-science applications as well as in integrated quantum photonics and quantum information processing as single-photon emitters. Single-particle spectroscopy of 10 nm QDs with 3.2 nm cores reveals strong photon antibunching attributed to fast (70 ps) Auger recombination of multiple excitons. The QDs exhibit very good photostability under strong optical excitation. We demonstrate that the antibunching is preserved when the QDs are excited above the saturation intensity of the fundamental-exciton transition. This result paves the way toward their usage as high-purity on-demand single-photon emitters at room temperature. Unconventionally, despite the strong Auger blockade mechanism, InP/ZnSe QDs also display very little luminescence intermittency ("blinking"), with a simple on/off blinking pattern. The analysis of single-particle luminescence statistics places these InP/ZnSe QDs in the class of nearly blinking-free QDs, with emission stability comparable to state-of-the-art thick-shell and alloyed-interface CdSe/CdS, but with improved single-photon purity.

  11. Single photon infrared emission spectroscopy: a study of IR emission from UV laser excited PAHs between 3 and 15 micrometers

    Science.gov (United States)

    Cook, D. J.; Schlemmer, S.; Balucani, N.; Wagner, D. R.; Harrison, J. A.; Steiner, B.; Saykally, R. J.

    1998-01-01

    Single-photon infrared emission spectroscopy (SPIRES) has been used to measure emission spectra from polycyclic aromatic hydrocarbons (PAHs). A supersonic free-jet expansion has been used to provide emission spectra of rotationally cold and vibrationally excited naphthalene and benzene. Under these conditions, the observed width of the 3.3-micrometers (C-H stretch) band resembles the bandwidths observed in experiments in which emission is observed from naphthalene with higher rotational energy. To obtain complete coverage of IR wavelengths relevant to the unidentified infrared bands (UIRs), UV laser-induced desorption was used to generate gas-phase highly excited PAHs. Lorentzian band shapes were convoluted with the monochromator-slit function in order to determine the widths of PAH emission bands under astrophysically relevant conditions. Bandwidths were also extracted from bands consisting of multiple normal modes blended together. These parameters are grouped according to the functional groups mostly involved in the vibration, and mean bandwidths are obtained. These bandwidths are larger than the widths of the corresponding UIR bands. However, when the comparison is limited to the largest PAHs studied, the bandwidths are slightly smaller than the corresponding UIR bands. These parameters can be used to model emission spectra from PAH cations and cations of larger PAHs, which are better candidate carriers of the UIRs.

  12. Extended calibration range for prompt photon emission in ion beam irradiation

    CERN Document Server

    Bellini, F.

    2014-01-01

    Monitoring the dose delivered during proton and carbon ion therapy is still a matter of research. Among the possible solutions, several exploit the measurement of the single photon emission from nuclear decays induced by the irradiation. To fully characterize such emission the detectors need development, since the energy spectrum spans the range above the MeV that is not traditionally used in medical applications. On the other hand, a deeper understanding of the reactions involving gamma production is needed in order to improve the physic models of Monte Carlo codes, relevant for an accurate prediction of the prompt-gamma energy spectrum.This paper describes a calibration technique tailored for the range of energy of interest and reanalyzes the data of the interaction of a 80MeV/u fully stripped carbon ion beam with a Poly-methyl methacrylate target. By adopting the FLUKA simulation with the appropriate calibration and resolution a significant improvement in the agreement between data and simulation is report...

  13. Extended calibration range for prompt photon emission in ion beam irradiation

    International Nuclear Information System (INIS)

    Bellini, F.; Boehlen, T.T.; Chin, M.P.W.; Collamati, F.; De Lucia, E.; Faccini, R.; Ferrari, A.; Lanza, L.; Mancini-Terracciano, C.; Marafini, M.; Mattei, I.; Morganti, S.; Ortega, P.G.; Patera, V.; Piersanti, L.; Russomando, A.; Sala, P.R.

    2014-01-01

    Monitoring the dose delivered during proton and carbon ion therapy is still a matter of research. Among the possible solutions, several exploit the measurement of the single photon emission from nuclear decays induced by the irradiation. To fully characterize such emission the detectors need development, since the energy spectrum spans the range above the MeV that is not traditionally used in medical applications. On the other hand, a deeper understanding of the reactions involving gamma production is needed in order to improve the physic models of Monte Carlo codes, relevant for an accurate prediction of the prompt-gamma energy spectrum. This paper describes a calibration technique tailored for the range of energy of interest and reanalyzes the data of the interaction of a 80 MeV/u fully stripped carbon ion beam with a Poly-methyl methacrylate target. By adopting the FLUKA simulation with the appropriate calibration and resolution a significant improvement in the agreement between data and simulation is reported

  14. Extended calibration range for prompt photon emission in ion beam irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Bellini, F. [Dipartimento di Fisica, Sapienza Università di Roma, Roma (Italy); INFN Sezione di Roma, Roma (Italy); Boehlen, T.T.; Chin, M.P.W. [CERN, Geneva (Switzerland); Collamati, F. [Dipartimento di Fisica, Sapienza Università di Roma, Roma (Italy); INFN Sezione di Roma, Roma (Italy); De Lucia, E. [Laboratori Nazionali di Frascati dell' INFN, Frascati (Italy); Faccini, R., E-mail: riccardo.faccini@roma1.infn.it [Dipartimento di Fisica, Sapienza Università di Roma, Roma (Italy); INFN Sezione di Roma, Roma (Italy); Ferrari, A. [CERN, Geneva (Switzerland); Lanza, L. [Dipartimento di Fisica, Sapienza Università di Roma, Roma (Italy); INFN Sezione di Roma, Roma (Italy); Mancini-Terracciano, C. [CERN, Geneva (Switzerland); Dipartimento di Fisica, Università Roma Tre, Roma (Italy); Marafini, M. [Museo Storico della Fisica e Centro Studi e Ricerche “E. Fermi”, Roma (Italy); INFN Sezione di Roma, Roma (Italy); Mattei, I. [Dipartimento di Fisica, Università Roma Tre, Roma (Italy); Laboratori Nazionali di Frascati dell' INFN, Frascati (Italy); Morganti, S. [INFN Sezione di Roma, Roma (Italy); Ortega, P.G. [CERN, Geneva (Switzerland); Patera, V. [Dipartimento di Scienze di Base e Applicate per Ingegneria, Sapienza Università di Roma, Roma (Italy); INFN Sezione di Roma, Roma (Italy); Piersanti, L. [Dipartimento di Scienze di Base e Applicate per Ingegneria, Sapienza Università di Roma, Roma (Italy); Laboratori Nazionali di Frascati dell' INFN, Frascati (Italy); Russomando, A. [Center for Life Nano Science@Sapienza, Istituto Italiano di Tecnologia, Roma (Italy); INFN Sezione di Roma, Roma (Italy); Sala, P.R. [INFN Sezione di Milano, Milano (Italy); and others

    2014-05-01

    Monitoring the dose delivered during proton and carbon ion therapy is still a matter of research. Among the possible solutions, several exploit the measurement of the single photon emission from nuclear decays induced by the irradiation. To fully characterize such emission the detectors need development, since the energy spectrum spans the range above the MeV that is not traditionally used in medical applications. On the other hand, a deeper understanding of the reactions involving gamma production is needed in order to improve the physic models of Monte Carlo codes, relevant for an accurate prediction of the prompt-gamma energy spectrum. This paper describes a calibration technique tailored for the range of energy of interest and reanalyzes the data of the interaction of a 80 MeV/u fully stripped carbon ion beam with a Poly-methyl methacrylate target. By adopting the FLUKA simulation with the appropriate calibration and resolution a significant improvement in the agreement between data and simulation is reported.

  15. A pragmatic guide to multiphoton microscope design

    Science.gov (United States)

    Young, Michael D.; Field, Jeffrey J.; Sheetz, Kraig E.; Bartels, Randy A.; Squier, Jeff

    2016-01-01

    Multiphoton microscopy has emerged as a ubiquitous tool for studying microscopic structure and function across a broad range of disciplines. As such, the intent of this paper is to present a comprehensive resource for the construction and performance evaluation of a multiphoton microscope that will be understandable to the broad range of scientific fields that presently exploit, or wish to begin exploiting, this powerful technology. With this in mind, we have developed a guide to aid in the design of a multiphoton microscope. We discuss source selection, optical management of dispersion, image-relay systems with scan optics, objective-lens selection, single-element light-collection theory, photon-counting detection, image rendering, and finally, an illustrated guide for building an example microscope. PMID:27182429

  16. Scanning near-field optical microscopy of quantum dots in photonic crystal cavities

    Energy Technology Data Exchange (ETDEWEB)

    Skacel, Matthias; Fiore, Andrea [COBRA Research Institute, Technical University Eindhoven, Den Dolech 2, 5600 MB Eindhoven (Netherlands); Prancardi, Marco; Gerardino, Annamaria [Institute of Photonics and Nanotechnology, CNR, via del Cineto Romano 42, 00156 Roma (Italy); Alloing, Blandine; Li Lianhe, E-mail: m.s.skacel@tue.n [Institute of Photonics and Quantum Electronics, EPFL, CH-1015 Lausanne (Switzerland)

    2010-09-01

    Nanophotonic devices are of major interest for research and future quantum communication applications. Due to their nanometer feature size the resolution limit of far-field microscopy poses a limitation on the characterization of their optical properties. A method to overcome the resolution limit is the Scanning Near-Field Optical Microscope (SNOM). By approaching a fiber tip into the close vicinity of the sample the optical emission in the near-field regime is collected. This way of collecting the light is not affected by the diffraction limit. We employ a low temperature SNOM to investigate the photoluminescence of InAs QDs emitting at 1300nm wavelength embedded in photonic crystal cavities. At each location of an image scan the tip is stopped and a spectrum is acquired. We then plot maps of the photoluminescence for each wavelength. With this instrument it is now possible to directly observe the coupling of QDs to photonic crystal cavities both spectrally and spatially. We show first results of photoluminescence mapping of InAs QDs in photonic crystal cavities.

  17. Development of novel emission tomography system

    Science.gov (United States)

    Fu, Geng

    . The detector offers the combination of an excellent intrinsic spatial resolution, a good signal-to-noise ratio (SNR), a large active area, and reasonable detection efficiency over the energy range from 27 to 140 keV. Based on I-EMCCD detector we developed a prototype dual-head single photon emission microscope (SPEM) system for mouse imaging. Both phantom and animal imaging experiments have been performed to evaluate system capabilities for ultra-high resolution SPECT imaging. In addition, we have presented a feasibility study of using emission tomography system for synchrotron X-ray fluorescence computer tomography (XFCT). Based on high resolution semiconductor detector and collimation aperture, X-ray fluorescence emission tomography (XFET) can offer more imaging information content by each detected photon and allow less scanning motion, which help to overcome the hurdle for current X-ray fluorescence computed tomography (XFCT) and improve imaging speed. CCD-based emission tomography system has been set up at the Advanced Photon Source (APS) for phantom and animal imaging. It has demonstrated that XFET is capable of acquiring 3D element distribution with a greatly improved imaging speed. Key words: SPECT, ERPC, I-EMCCD, SPEM, APS, and XFET

  18. Density-matrix approach for the electroluminescence of molecules in a scanning tunneling microscope.

    Science.gov (United States)

    Tian, Guangjun; Liu, Ji-Cai; Luo, Yi

    2011-04-29

    The electroluminescence (EL) of molecules confined inside a nanocavity in the scanning tunneling microscope possesses many intriguing but unexplained features. We present here a general theoretical approach based on the density-matrix formalism to describe the EL from molecules near a metal surface induced by both electron tunneling and localized surface plasmon excitations simultaneously. It reveals the underlying physical mechanism for the external bias dependent EL. The important role played by the localized surface plasmon on the EL is highlighted. Calculations for porphyrin derivatives have reproduced corresponding experimental spectra and nicely explained the observed unusual large variation of emission spectral profiles. This general theoretical approach can find many applications in the design of molecular electronic and photonic devices.

  19. Use of an axisymmetric microscope with electronic readout for collecting soft X-ray images

    International Nuclear Information System (INIS)

    Cavailler, C.; Henry, P.; Launspach, J.; De Mascureau, J.; Millerioux, M.; Rostaing, M.; Sauneuf, R.

    1984-08-01

    The axisymmetric microscope, first discussed by Wolter, provides high resolution and sensitivity for investigating the soft X-ray emission of laser-driven plasmas. Such a device having a 10 X magnification has been constructed. We present a comparison between the images of laser-driven plasmas given by this microscope and by a 10 X pinhole camera. Until now these images were recorded on X-ray film. We have shown that film could be replaced by C.C.D. in a pinhole camera when the photon energy lies within the 1-10 keV range. Below 1 keV the quantum yield is too low so we have used an image converter tube made by RTC. It is a diode-inverter tube with a soft X-ray photocathode and a P20 phosphor deposited on an optic fiber plate. The electronic image appearing on the screen is read by a C.C.D. working in the visible spectral fields. An electronic image readout chain, which is identical to those associated with streak cameras, then processes automatically and immediately the images given by the microscope [fr

  20. Photonic band edge assisted spontaneous emission enhancement from all Er3+ 1-D photonic band gap structure

    Science.gov (United States)

    Chiasera, A.; Meroni, C.; Varas, S.; Valligatla, S.; Scotognella, F.; Boucher, Y. G.; Lukowiak, A.; Zur, L.; Righini, G. C.; Ferrari, M.

    2018-06-01

    All Er3+ doped dielectric 1-D Photonic Band Gap Structure was fabricated by rf-sputtering technique. The structure was constituted by of twenty pairs of SiO2/TiO2 alternated layers doped with Er3+ ions. The scanning electron microscopy was used to check the morphology of the structure. Transmission measurements put in evidence the stop band in the range 1500 nm-1950 nm. The photoluminescence measurements were obtained by optically exciting the sample and detecting the emitted light in the 1.5 μm region at different detection angles. Luminescence spectra and luminescence decay curves put in evidence that the presence of the stop band modify the emission features of the Er3+ ions.

  1. Non-Poissonian photon statistics from macroscopic photon cutting materials.

    Science.gov (United States)

    de Jong, Mathijs; Meijerink, Andries; Rabouw, Freddy T

    2017-05-24

    In optical materials energy is usually extracted only from the lowest excited state, resulting in fundamental energy-efficiency limits such as the Shockley-Queisser limit for single-junction solar cells. Photon-cutting materials provide a way around such limits by absorbing high-energy photons and 'cutting' them into multiple low-energy excitations that can subsequently be extracted. The occurrence of photon cutting or quantum cutting has been demonstrated in a variety of materials, including semiconductor quantum dots, lanthanides and organic dyes. Here we show that photon cutting results in bunched photon emission on the timescale of the excited-state lifetime, even when observing a macroscopic number of optical centres. Our theoretical derivation matches well with experimental data on NaLaF 4 :Pr 3+ , a material that can cut deep-ultraviolet photons into two visible photons. This signature of photon cutting can be used to identify and characterize new photon-cutting materials unambiguously.

  2. Hard photon emission from high energy electrons and positrons in single crystals

    International Nuclear Information System (INIS)

    Bajer, V.N.; Katkov, V.M.; Strakhovenko, V.M.

    1991-01-01

    A radiation of electrons and positrons in single crystals in coherent bremsstrahlung (CBS) region has been considered for the case when CBS has the most hard spectrum. Under this condition a particle moves near a crystalline plane (in fcc(d) crystal for axis (001) this is the plane (110)) and influence of the continuous plane potential should be taken into account. This potential gives additional contribution in soft part of the spectrum and affects on hard photon emission. Observation of this phenomena at high energy is discussed. 14 refs.; 5 figs.; 1 tab

  3. Exploring the microscopic origin of exchange bias with photoelectron emission microscopy (invited)

    International Nuclear Information System (INIS)

    Scholl, A.; Nolting, F.; Stohr, J.; Regan, T.; Luning, J.; Seo, J. W.; Locquet, J.-P.; Fompeyrine, J.; Anders, S.; Ohldag, H.

    2001-01-01

    It is well known that magnetic exchange coupling across the ferromagnet - antiferromagnet interface results in an unidirectional magnetic anisotropy of the ferromagnetic layer, called exchange bias. Despite large experimental and theoretical efforts, the origin of exchange bias is still controversial, mainly because detection of the interfacial magnetic structure is difficult. We have applied photoelectron emission microscopy (PEEM) on several ferromagnet - antiferromagnet thin-film structures and microscopically imaged the ferromagnetic and the antiferromagnetic structure with high spatial resolution. Taking advantage of the surface sensitivity and elemental specificity of PEEM, the magnetic configuration and critical properties such as the Neel temperature were determined on LaFeO 3 and NiO thin films and single crystals. On samples coated with a ferromagnetic layer, we microscopically observe exchange coupling across the interface, causing a clear correspondence of the domain structures in the adjacent ferromagnet and antiferromagnet. Field dependent measurements reveal a strong uniaxial anisotropy in individual ferromagnetic domains. A local exchange bias was observed even in not explicitly field-annealed samples, caused by interfacial uncompensated magnetic spins. These experiments provide highly desired information on the relative orientation of electron spins at the interface between ferromagnets and antiferromagnets. [copyright] 2001 American Institute of Physics

  4. AURORA on MEGSAT 1: a photon counting observatory for the Earth UV night-sky background and Aurora emission

    International Nuclear Information System (INIS)

    Monfardini, A.; Trampus, P.; Stalio, R.; Mahne, N.; Battiston, R.; Menichelli, M.; Mazzinghi, P.

    2001-01-01

    A low-mass, low-cost photon-counting scientific payload has been developed and launched on a commercial microsatellite in order to study the near-UV night-sky background emission with a telescope nicknamed 'Notte' and the Aurora emission with 'Alba'. AURORA, this is the name of the experiment, will determine, with the 'Notte' channel, the overall night-side photon background in the 300-400 nm spectral range, together with a particular 2 + N 2 line (λ c =337 nm). The 'Alba' channel, on the other hand, will study the Aurora emissions in four different spectral bands (FWHM=8.4-9.6 nm) centered on: 367 nm (continuum evaluation), 391 nm (1 - N + 2 ), 535 nm (continuum evaluation), 560 nm (OI). The instrument has been launched on the 26 September, 2000 from the Baikonur cosmodrome on a modified SS18 Dnepr-1 'Satan' rocket. The satellite orbit is nearly circular (h apogee =648 km, e=0.0022), and the inclination of the orbital plane is 64.56 deg. An overview of the techniques adopted is given in this paper

  5. Enhancement of molecular sensitivity in positron emission tomography with quantum correlation of γ-ray photons

    Science.gov (United States)

    Sato, K.; Kobayashi, Y.

    2015-05-01

    Enhancement of molecular sensitivity in positron emission tomography (PET) has long been discussed with respect to imaging instrumentation and algorithms for data treatment. Here, the molecular sensitivity in PET is discussed on the basis of 2-dimensional coincident measurements of 511 keV γ ray photons resultant from two-photon annihilation. Introduction of an additional selection window based on the energy sum and difference of the coincidently measured γ ray photons, without any significant instrumental and algorithmic changes, showed an improvement in the signal-to-noise ratio (SNR) by an order of magnitude. Improvement of performance characteristics in the PET imaging system was demonstrated by an increase in the noise equivalent count rate (NECR) which takes both the SNR and the detection efficiency into consideration. A further improvement of both the SNR and the NECR is expected for the present system in real clinical and in-vivo environments, where much stronger positron sources are employed.

  6. Enhancement of molecular sensitivity in positron emission tomography with quantum correlation of γ-ray photons

    International Nuclear Information System (INIS)

    Sato, K.; Kobayashi, Y.

    2015-01-01

    Enhancement of molecular sensitivity in positron emission tomography (PET) has long been discussed with respect to imaging instrumentation and algorithms for data treatment. Here, the molecular sensitivity in PET is discussed on the basis of 2-dimensional coincident measurements of 511 keV γ ray photons resultant from two-photon annihilation. Introduction of an additional selection window based on the energy sum and difference of the coincidently measured γ ray photons, without any significant instrumental and algorithmic changes, showed an improvement in the signal-to-noise ratio (SNR) by an order of magnitude. Improvement of performance characteristics in the PET imaging system was demonstrated by an increase in the noise equivalent count rate (NECR) which takes both the SNR and the detection efficiency into consideration. A further improvement of both the SNR and the NECR is expected for the present system in real clinical and in-vivo environments, where much stronger positron sources are employed

  7. The mechanism and properties of bio-photon emission and absorption in protein molecules in living systems

    Science.gov (United States)

    Pang, Xiao-feng

    2012-05-01

    The mechanism and properties of bio-photon emission and absorption in bio-tissues were studied using Pang's theory of bio-energy transport, in which the energy spectra of protein molecules are obtained from the discrete dynamic equation. From the energy spectra, it was determined that the protein molecules could both radiate and absorb bio-photons with wavelengths of energy level transitions of the excitons. These results were consistent with the experimental data; this consisted of infrared absorption data from collagen, bovine serum albumin, the protein-like molecule acetanilide, plasma, and a person's finger, and the laser-Raman spectra of acidity I-type collagen in the lungs of a mouse, and metabolically active Escherichia coli. We further elucidated the mechanism responsible for the non-thermal biological effects produced by the infrared light absorbed by the bio-tissues, using the above results. No temperature rise was observed; instead, the absorbed infrared light promoted the vibrations of amides as well the transport of the bio-energy from one place to other in the protein molecules, which changed their conformations. These experimental results, therefore, not only confirmed the validity of the mechanism of bio-photon emission, and the newly developed theory of bio-energy transport mentioned above, but also explained the mechanism and properties of the non-thermal biological effects produced by the absorption of infrared light by the living systems.

  8. Search for two-photon emission from 2S states of low-Z muonic atoms

    International Nuclear Information System (INIS)

    Carter, A.L.; Hincks, E.P.; Cox, C.R.; Dodson, G.W.; Eckhause, M.; Kane, J.R.; Rushton, A.M.; Siegel, R.T.; Welsh, R.E.; Hargrove, C.K.; Mes, H.; Dixit, M.S.; National Research Council of Canada, Ottawa, Ontario)

    1983-01-01

    A search for two-photon emission from 2S states of low-Z muonic atoms has been made. Intrinsic Ge detectors were positioned around target of Li, Be, B, or their hydrides, or a vessel containing B 2 H 6 , H 2 , or O 2 . Upper limits on the fraction of stopping muons which formed metastable 2S states range from approx.= 10 - 3 to 10 - 5 . (orig.)

  9. Transition of lasing modes in polymeric opal photonic crystal resonating cavity.

    Science.gov (United States)

    Shi, Lan-Ting; Zheng, Mei-Ling; Jin, Feng; Dong, Xian-Zi; Chen, Wei-Qiang; Zhao, Zhen-Sheng; Duan, Xuan-Ming

    2016-06-10

    We demonstrate the transition of lasing modes in the resonating cavity constructed by polystyrene opal photonic crystals and 7 wt. % tert-butyl Rhodamine B doped polymer film. Both single mode and multiple mode lasing emission are observed from the resonating cavity. The lasing threshold is determined to be 0.81  μJ/pulse for single mode lasing emission and 2.25  μJ/pulse for multiple mode lasing emission. The single mode lasing emission is attributed to photonic lasing resulting from the photonic bandgap effect of the opal photonic crystals, while the multiple mode lasing emission is assigned to random lasing due to the defects in the photonic crystals. The result would benefit the development of low threshold polymeric solid state photonic crystal lasers.

  10. Promising role of single photon emission computed tomography/computed tomography in Meckel's scan

    International Nuclear Information System (INIS)

    Jain, Anurag; Chauhan, MS; Pandit, AG; Kumar, Rajeev; Sharma, Amit

    2012-01-01

    Meckel's scan is a common procedure performed in nuclear medicine. Single-photon emission computed tomography/computed tomography (SPECT/CT) in a suspected case of heterotopic location of gastric mucosa can increase the accuracy of its anatomic localization. We present two suspected cases of Meckel's diverticulum in, which SPECT/CT co-registration has helped in better localization of the pathology

  11. Development of a high brightness ultrafast Transmission Electron Microscope based on a laser-driven cold field emission source.

    Science.gov (United States)

    Houdellier, F; Caruso, G M; Weber, S; Kociak, M; Arbouet, A

    2018-03-01

    We report on the development of an ultrafast Transmission Electron Microscope based on a cold field emission source which can operate in either DC or ultrafast mode. Electron emission from a tungsten nanotip is triggered by femtosecond laser pulses which are tightly focused by optical components integrated inside a cold field emission source close to the cathode. The properties of the electron probe (brightness, angular current density, stability) are quantitatively determined. The measured brightness is the largest reported so far for UTEMs. Examples of imaging, diffraction and spectroscopy using ultrashort electron pulses are given. Finally, the potential of this instrument is illustrated by performing electron holography in the off-axis configuration using ultrashort electron pulses. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. Position Dependent Spontaneous Emission Spectra of a Λ-Type Atomic System Embedded in a Defective Photonic Crystal

    International Nuclear Information System (INIS)

    Entezar, S. Roshan

    2012-01-01

    We investigate the position dependent spontaneous emission spectra of a Λ-type three-level atom with one transition coupled to the free vacuum reservoir and the other one coupled to a double-band photonic band gap reservoir with a defect mode in the band gap. It is shown that, for the atom at the defect location, we have a two-peak spectrum with a wide dark line due to the strong coupling between the atom and the defect mode. While, when the atom is far from the defect location (or in the absence of the defect mode), the spectrum has three peaks with two dark lines due to the coupling between the atom and the photonic band gap reservoir with the largest density of states near the band edges. On the other hand, we have a four-peak spectrum for the atom at the space in between. Moreover, the average spontaneous emission spectra of the atoms uniformly embedded in high dielectric or low dielectric regions are described. It is shown that the atoms embedded in high (low) dielectric regions far from the defect location, effectively couple to the modes of the lower (upper) photonic band. However, the atoms embedded in high dielectric or low dielectric regions at the defect location, are coupled mainly to the defect modes. While, the atoms uniformly embedded in high (low) dielectric regions with a normal distance from the defect location, are coupled to both of defect and lower (upper) photonic band modes. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  13. Synthesis of novel fluorene-based two-photon absorbing molecules and their applications in optical data storage, microfabrication, and stimulated emission depletion

    Science.gov (United States)

    Yanez, Ciceron

    2009-12-01

    Two-photon absorption (2PA) has been used for a number of scientific and technological applications, exploiting the fact that the 2PA probability is directly proportional to the square of the incident light intensity (while one-photon absorption bears a linear relation to the incident light intensity). This intrinsic property of 2PA leads to 3D spatial localization, important in fields such as optical data storage, fluorescence microscopy, and 3D microfabrication. The spatial confinement that 2PA enables has been used to induce photochemical and photophysical events in increasingly smaller volumes and allowed nonlinear, 2PA-based, technologies to reach sub-diffraction limit resolutions. The primary focus of this dissertation is the development of novel, efficient 2PA, fluorene-based molecules to be used either as photoacid generators (PAGs) or fluorophores. A second aim is to develop more effective methods of synthesizing these compounds. As a third and final objective, the new molecules were used to develop a write-once-read many (WORM) optical data storage system, and stimulated emission depletion probes for bioimaging. In Chapter I, the microwave-assisted synthesis of triarylsulfonium salt photoacid generators (PAGs) from their diphenyliodonium counterparts is reported. The microwave-assisted synthesis of these novel sulfonium salts afforded reaction times 90 to 420 times faster than conventional thermal conditions, with photoacid quantum yields of new sulfonium PAGs ranging from 0.01 to 0.4. These PAGs were used to develop a fluorescence readout-based, nonlinear three-dimensional (3D) optical data storage system (Chapter II). In this system, writing was achieved by acid generation upon two-photon absorption (2PA) of a PAG (at 710 or 730 nm). Readout was then performed by interrogating two-photon absorbing dyes, after protonation, at 860 nm. Two-photon recording and readout of voxels was demonstrated in five and eight consecutive, crosstalk-free layers within a

  14. Near-unity efficiency, single-photon sources based on tapered photonic nanowires

    DEFF Research Database (Denmark)

    Bleuse, Joël; Munsch, Mathieu; Claudon, Julien

    2012-01-01

    Single-photon emission from excitons in InAs Quantum Dots (QD) embedded in GaAs Tapered Photonic Wires (TPW) already demonstrated a 0.72 collection efficiency, with TPWs were the apex is the sharp end of the cone. Going to alternate designs, still based on the idea of the adiabatic deconfinement...... of the quasi-Gaussian emission mode, but with inverted TPW where the apex is the cone's base, leads to even larger efficiencies. In addition, these inverted TPWs make the electric pumping of the emitters compatible with these large efficiencies....

  15. Nuclear photon science with inverse compton photon beam

    International Nuclear Information System (INIS)

    Fujiwara, Mamoru

    2007-01-01

    Recent developments of the synchrotron radiation facilities and intense lasers are now guiding us to a new research frontier with probes of a high energy GeV photon beam and an intense and short pulse MeV γ-ray beam. New directions of the science developments with photo-nuclear reactions are discussed. The inverse Compton γ-ray has two good advantages for searching for a microscopic quantum world; they are 1) good emittance and 2) high linear and circular polarizations. With these advantages, photon beams in the energy range from MeV to GeV are used for studying hadron structure, nuclear structure, astrophysics, materials science, as well as for applying medical science. (author)

  16. Computed tomography angiography and perfusion to assess coronary artery stenosis causing perfusion defects by single photon emission computed tomography

    DEFF Research Database (Denmark)

    Rochitte, Carlos E; George, Richard T; Chen, Marcus Y

    2014-01-01

    AIMS: To evaluate the diagnostic power of integrating the results of computed tomography angiography (CTA) and CT myocardial perfusion (CTP) to identify coronary artery disease (CAD) defined as a flow limiting coronary artery stenosis causing a perfusion defect by single photon emission computed...... emission computed tomography (SPECT/MPI). Sixteen centres enroled 381 patients who underwent combined CTA-CTP and SPECT/MPI prior to conventional coronary angiography. All four image modalities were analysed in blinded independent core laboratories. The prevalence of obstructive CAD defined by combined ICA...... tomography (SPECT). METHODS AND RESULTS: We conducted a multicentre study to evaluate the accuracy of integrated CTA-CTP for the identification of patients with flow-limiting CAD defined by ≥50% stenosis by invasive coronary angiography (ICA) with a corresponding perfusion deficit on stress single photon...

  17. Single-photon sources based on single molecules in solids

    International Nuclear Information System (INIS)

    Moerner, W E

    2004-01-01

    Single molecules in suitable host crystals have been demonstrated to be useful single-photon emitters both at liquid-helium temperatures and at room temperature. The low-temperature source achieved controllable emission of single photons from a single terrylene molecule in p-terphenyl by an adiabatic rapid passage technique. In contrast with almost all other single-molecule systems, terrylene single molecules show extremely high photostability under continuous, high-intensity irradiation. A room-temperature source utilizing this material has been demonstrated, in which fast pumping into vibrational sidebands of the electronically excited state achieved efficient inversion of the emissive level. This source yielded a single-photon emission probability p(1) of 0.86 at a detected count rate near 300 000 photons s -1 , with very small probability of emission of more than one photon. Thus, single molecules in solids can be considered as contenders for applications of single-photon sources such as quantum key distribution

  18. Search for two-photon emission from 2S states of low-Z muonic atoms

    Energy Technology Data Exchange (ETDEWEB)

    Carter, A.L.; Hincks, E.P. (Carleton Univ., Ottawa, Ontario (Canada). Dept. of Physics); Cox, C.R.; Dodson, G.W.; Eckhause, M.; Kane, J.R.; Rushton, A.M.; Siegel, R.T.; Welsh, R.E. (College of William and Mary, Williamsburg, VA (USA). Dept. of Physics); Hargrove, C.K.

    1983-05-12

    A search for two-photon emission from 2S states of low-Z muonic atoms has been made. Intrinsic Ge detectors were positioned around target of Li, Be, B, or their hydrides, or a vessel containing B/sub 2/H/sub 6/, H/sub 2/, or O/sub 2/. Upper limits on the fraction of stopping muons which formed metastable 2S states range from approximately = 10/sup -3/ to 10/sup -5/.

  19. Switching mechanism due to the spontaneous emission cancellation in photonic band gap materials doped with nano-particles

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Mahi R. [Department of Physics and Astronomy, University of Western Ontario, London, Canada N6A 3K7 (Canada)]. E-mail: msingh@uwo.ca

    2007-03-26

    We have investigated the switching mechanism due to the spontaneous emission cancellation in a photonic band gap (PBG) material doped with an ensemble of four-level nano-particles. The effect of the dipole-dipole interaction has also been studied. The linear susceptibility has been calculated in the mean field theory. Numerical simulations for the imaginary susceptibility are performed for a PBG material which is made from periodic dielectric spheres. It is predicted that the system can be switched between the absorbing state and the non-absorbing state by changing the resonance energy within the energy bands of the photonic band gap material.0.

  20. Photonics4All Crossword: Light Scientist

    OpenAIRE

    Dr. Adam, Aurèle

    2015-01-01

    Photonics4All developed the quiz “The Optics Scientist“. It tests our knowledge regarding famous people in optics & photonics. 14 famous scientists you should know, if you consider yourself a photoncis experts, are presented! For instance: Do you know the Dutch scientist who lived in Delft and invented the microscope? …find our more & test yourself, your friends, co-workers, students or family members!

  1. Ultrafast electrical control of a resonantly driven single photon source

    International Nuclear Information System (INIS)

    Cao, Y.; Bennett, A. J.; Ellis, D. J. P.; Shields, A. J.; Farrer, I.; Ritchie, D. A.

    2014-01-01

    We demonstrate generation of a pulsed stream of electrically triggered single photons in resonance fluorescence, by applying high frequency electrical pulses to a single quantum dot in a p-i-n diode under resonant laser excitation. Single photon emission was verified, with the probability of multiple photon emission reduced to 2.8%. We show that despite the presence of charge noise in the emission spectrum of the dot, resonant excitation acts as a “filter” to generate narrow bandwidth photons

  2. The contribution of single photon emission computed tomography in the clinical assessment of Alzheimer type dementia

    International Nuclear Information System (INIS)

    Boudousq, V.; Collombier, L.; Kotzki, P.O.

    1999-01-01

    Interest of brain single-photon emission computed tomography to support clinical diagnosis of Alzheimer-type dementia is now established. Numerous studies have reported a decreased perfusion in the association cortex of the parietal lobe and the posterior temporal regions. In patients with mild cognitive complaints, the presence of focal hypoperfusion may increase substantially the probability of the disease. In addition, emission tomography emerges as a helpful tool in situation in which there is diagnostic doubt. In this case, the presence of temporo-parietal perfusion deficit associated with hippocampal atrophy on MRI or X-ray computed tomography contributes to diagnostic accuracy. However, some studies suggest that emission tomography may be useful for preclinical prediction of Alzheimer's disease and to predict cognitive decline. (author)

  3. Scanning Auger Electron Microscope

    Data.gov (United States)

    Federal Laboratory Consortium — A JEOL model 7830F field emission source, scanning Auger microscope.Specifications / Capabilities:Ultra-high vacuum (UHV), electron gun range from 0.1 kV to 25 kV,...

  4. Local detection efficiency of a NbN superconducting single photon detector explored by a scattering scanning near-field optical microscope.

    Science.gov (United States)

    Wang, Qiang; Renema, Jelmer J; Engel, Andreas; van Exter, Martin P; de Dood, Michiel J A

    2015-09-21

    We propose an experiment to directly probe the local response of a superconducting single photon detector using a sharp metal tip in a scattering scanning near-field optical microscope. The optical absorption is obtained by simulating the tip-detector system, where the tip-detector is illuminated from the side, with the tip functioning as an optical antenna. The local detection efficiency is calculated by considering the recently introduced position-dependent threshold current in the detector. The calculated response for a 150 nm wide detector shows a peak close to the edge that can be spatially resolved with an estimated resolution of ∼ 20 nm, using a tip with parameters that are experimentally accessible.

  5. AURORA on MEGSAT 1 a photon counting observatory for the Earth UV night-sky background and Aurora emission

    CERN Document Server

    Monfardini, A; Stalio, R; Mahne, N; Battiston, R; Menichelli, M; Mazzinghi, P

    2001-01-01

    A low-mass, low-cost photon-counting scientific payload has been developed and launched on a commercial microsatellite in order to study the near-UV night-sky background emission with a telescope nicknamed 'Notte' and the Aurora emission with 'Alba'. AURORA, this is the name of the experiment, will determine, with the 'Notte' channel, the overall night-side photon background in the 300-400 nm spectral range, together with a particular 2 sup + N sub 2 line (lambda sub c =337 nm). The 'Alba' channel, on the other hand, will study the Aurora emissions in four different spectral bands (FWHM=8.4-9.6 nm) centered on: 367 nm (continuum evaluation), 391 nm (1 sup - N sup + sub 2), 535 nm (continuum evaluation), 560 nm (OI). The instrument has been launched on the 26 September, 2000 from the Baikonur cosmodrome on a modified SS18 Dnepr-1 'Satan' rocket. The satellite orbit is nearly circular (h sub a sub p sub o sub g sub e sub e =648 km, e=0.0022), and the inclination of the orbital plane is 64.56 deg. An overview of...

  6. Biological Considerations When Comparing Proton Therapy. With Photon Therapy

    NARCIS (Netherlands)

    Paganetti, Harald; van Luijk, Peter

    Owing to the limited availability of data on the outcome of proton therapy, treatments are generally optimized based on broadly available data on photon-based treatments. However, the microscopic pattern of energy deposition of protons differs from that of photons, leading to a different biological

  7. Optical characterication of probes for photon scanning tunnelling microscopy

    DEFF Research Database (Denmark)

    Vohnsen, Brian; Bozhevolnyi, Sergey I.

    1999-01-01

    The photon scanning tunnelling microscope is a well-established member of the family of scanning near-field optical microscopes used for optical imaging at the sub-wavelength scale. The quality of the probes, typically pointed uncoated optical fibres, used is however difficult to evaluate...

  8. Spontaneous emission spectrum from a V-type three-level atom in a double-band photonic crystal

    International Nuclear Information System (INIS)

    Zhang Han Zhuang; Tang Sing Hai; Dong Po; He Jun

    2002-01-01

    The spontaneous emission spectrum from a V-type three-level atom embedded in a double-band photonic band gap (PBG) material has been investigated for the first time. Most interestingly it is shown that there is not only a black dark line, but also a narrow spontaneous line near the edges of the double photonic band. The positions of the dark line and narrow spontaneous line are near the transition from an empty upper level to a lower level. The lines stem from destructive and constructive quantum interferences, which induce population transfer between the two upper levels, in the PBG reservoirs. The effects of system parameters on the interference have been discussed in detail

  9. Photonic bandgap structure of 3-D fcc silica nanospheres

    Energy Technology Data Exchange (ETDEWEB)

    Woo, Y. K.; Ha, N. Y.; Hwang, Ji Soo; Chang, H. J.; Wu, J. W. [Dept. of Physics, Ewha Womans University, Seoul (Korea, Republic of)

    2002-07-01

    Photonic crystal is an artificial optical material with a periodic dielectric potential, hence exhibiting a bandgap for a propagating electromagnetic wave. We fabricated crystal possessing 3-D fcc opal structure from silica nanospheres. The crystals are self-assembled on a flat glass by evaporating the solvent in the nanosphere suspension at the room temperature. The suspension consists of silica nanospheres with a diameter of 200 nm. The microscopic arrangement of nanospheres is identified by a scanning electron microscope, the resulting structure being fcc.Transmission spectrum of the fabricated photonic crystal in the visible and near-infrared regions is measured at different incident angles to find the distinct Bragg peaks, analysis of which further confirmed the fcc structure of the photonic crystal. From the optical microscopic image, we find that the opal domain varies from 30 μm to 125 μm in size. In order to relate the observed Bragg peaks with the microscopic arrangement of silica nanospheres, we introduced the scalar wave approximation, where the electric field in the medium is treated as a scalar rather than a vector quantity. It is found that the theoretical prediction of the position of bandgap is in a good agreement with the experimental measurement.

  10. Photonic bandgap structure of 3-D fcc silica nanospheres

    International Nuclear Information System (INIS)

    Woo, Y. K.; Ha, N. Y.; Hwang, Ji Soo; Chang, H. J.; Wu, J. W.

    2002-01-01

    Photonic crystal is an artificial optical material with a periodic dielectric potential, hence exhibiting a bandgap for a propagating electromagnetic wave. We fabricated crystal possessing 3-D fcc opal structure from silica nanospheres. The crystals are self-assembled on a flat glass by evaporating the solvent in the nanosphere suspension at the room temperature. The suspension consists of silica nanospheres with a diameter of 200 nm. The microscopic arrangement of nanospheres is identified by a scanning electron microscope, the resulting structure being fcc.Transmission spectrum of the fabricated photonic crystal in the visible and near-infrared regions is measured at different incident angles to find the distinct Bragg peaks, analysis of which further confirmed the fcc structure of the photonic crystal. From the optical microscopic image, we find that the opal domain varies from 30 μm to 125 μm in size. In order to relate the observed Bragg peaks with the microscopic arrangement of silica nanospheres, we introduced the scalar wave approximation, where the electric field in the medium is treated as a scalar rather than a vector quantity. It is found that the theoretical prediction of the position of bandgap is in a good agreement with the experimental measurement.

  11. Brain single photon emission computed tomography in neonates

    International Nuclear Information System (INIS)

    Denays, R.; Van Pachterbeke, T.; Tondeur, M.

    1989-01-01

    This study was designed to rate the clinical value of [ 123 I]iodoamphetamine (IMP) or [ 99m Tc] hexamethyl propylene amine oxyme (HM-PAO) brain single photon emission computed tomography (SPECT) in neonates, especially in those likely to develop cerebral palsy. The results showed that SPECT abnormalities were congruent in most cases with structural lesions demonstrated by ultrasonography. However, mild bilateral ventricular dilatation and bilateral subependymal porencephalic cysts diagnosed by ultrasound were not associated with an abnormal SPECT finding. In contrast, some cortical periventricular and sylvian lesions and all the parasagittal lesions well visualized in SPECT studies were not diagnosed by ultrasound scans. In neonates with subependymal and/or intraventricular hemorrhage the existence of a parenchymal abnormality was only diagnosed by SPECT. These results indicate that [ 123 I]IMP or [ 99m Tc]HM-PAO brain SPECT shows a potential clinical value as the neurodevelopmental outcome is clearly related to the site, the extent, and the number of cerebral lesions. Long-term clinical follow-up is, however, mandatory in order to define which SPECT abnormality is associated with neurologic deficit

  12. Multi-photon microscope driven by novel green laser pump

    DEFF Research Database (Denmark)

    Marti, Dominik; Djurhuus, Martin; Jensen, Ole Bjarlin

    2016-01-01

    Multi-photon microscopy is extensively used in research due to its superior possibilities when compared to other microscopy modalities. The technique also has the possibility to advance diagnostics in clinical applications, due to its capabilities complementing existing technology in a multimodal...

  13. Spectrum of acetylene fluorescence excited by single XUV photons

    International Nuclear Information System (INIS)

    Schmieder, R.W.

    1982-01-01

    The spectrum of visible emission from photofragments of acetylene excited by single 16.85 eV photons has been recorded for the first time. The spectrum is dominated by the Swan and Deslandres-d'Azambuja bands of C 2 and the 431.5 nm band of CH. The yields of these emissions are of the order 10 -3 photons per absorbed incident photon. The experimental conditions suggest that the emission results from primary C* 2 and CH* photofragments

  14. Attenuation correction in pulmonary and myocardial single photon emission computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Almquist, H

    2000-01-01

    The objective was to develop and validate methods for single photon emission computed tomography, SPECT, allowing quantitative physiologic and diagnostic studies of lung and heart. A method for correction of variable attenuation in SPECT, based on transmission measurements before administration of an isotope to the subject, was developed and evaluated. A protocol based upon geometrically well defined phantoms was developed. In a mosaic pattern phantom count rates were corrected from 39-43% to 101-110% of reference. In healthy subjects non-gravitational pulmonary perfusion gradients observed without attenuation correctionwere artefacts caused by attenuation. Pulmonary density in centre of right lung, obtained from the transmission measurement, was 0.28 {+-} 0.03 g/ml in normal subjects. Mean density was lower in large lungs compared to smaller ones. We also showed that regional ventilation/perfusion ratios could be measured with SPECT, using the readily available tracer {sup 133}Xe. Because of the low energy of {sup 133}Xe this relies heavily upon attenuation correction. A commercially available system for attenuation correction with simultaneous emission and transmission, considered to improve myocardial SPECT, performed erroneously. This could lead to clinical misjudgement. We considered that manufacturer-independent pre-clinical tests are required. In a test of two other commercial systems, based on different principles, an adapted variant of our initial protocol was proven useful. Only one of the systems provided correct emission count rates independently on phantom configuration. Errors in the other system were related to inadequate compensation of the influence of emission activity on the transmission study.

  15. Attenuation correction in pulmonary and myocardial single photon emission computed tomography

    International Nuclear Information System (INIS)

    Almquist, H.

    2000-01-01

    The objective was to develop and validate methods for single photon emission computed tomography, SPECT, allowing quantitative physiologic and diagnostic studies of lung and heart. A method for correction of variable attenuation in SPECT, based on transmission measurements before administration of an isotope to the subject, was developed and evaluated. A protocol based upon geometrically well defined phantoms was developed. In a mosaic pattern phantom count rates were corrected from 39-43% to 101-110% of reference. In healthy subjects non-gravitational pulmonary perfusion gradients observed without attenuation correction were artefacts caused by attenuation. Pulmonary density in centre of right lung, obtained from the transmission measurement, was 0.28 ± 0.03 g/ml in normal subjects. Mean density was lower in large lungs compared to smaller ones. We also showed that regional ventilation/perfusion ratios could be measured with SPECT, using the readily available tracer 133 Xe. Because of the low energy of 133 Xe this relies heavily upon attenuation correction. A commercially available system for attenuation correction with simultaneous emission and transmission, considered to improve myocardial SPECT, performed erroneously. This could lead to clinical misjudgement. We considered that manufacturer-independent pre-clinical tests are required. In a test of two other commercial systems, based on different principles, an adapted variant of our initial protocol was proven useful. Only one of the systems provided correct emission count rates independently on phantom configuration. Errors in the other system were related to inadequate compensation of the influence of emission activity on the transmission study

  16. The High Energy Photons Emission from Solar Flares Observed by SZ2-XD

    Science.gov (United States)

    Wang, Huanyu; Li, Xinqiao; Ma, Yuqian; Zhang, Chengmo; Xu, Yupeng; Wang, Jingzhou; Chen, Guoming

    The spectra and light curve of near a hundred Solar X-ray Flare events, which were observed by SZ2/XD in the energy band of 10-800 keV during 2001, have been investigated. The events covered from C to X-class flares, which are shown different characters of high energy photons emission. The results will be presented in this paper. The discussions will be made especially for 3 of the brightest X-class solar flares SF010402(X20),SF010406(X5.6) and SF010415 (X14.4, a GLE event).

  17. Representation of photon limited data in emission tomography using origin ensembles

    Energy Technology Data Exchange (ETDEWEB)

    Sitek, A [Radiology Department, Brigham and Women' s Hospital and Harvard Medical School, 75 Francis Street, Boston, MA 02115 (United States)], E-mail: asitek@bwh.harvard.edu

    2008-06-21

    Representation and reconstruction of data obtained by emission tomography scanners are challenging due to high noise levels in the data. Typically, images obtained using tomographic measurements are represented using grids. In this work, we define images as sets of origins of events detected during tomographic measurements; we call these origin ensembles (OEs). A state in the ensemble is characterized by a vector of 3N parameters Y, where the parameters are the coordinates of origins of detected events in a three-dimensional space and N is the number of detected events. The 3N-dimensional probability density function (PDF) for that ensemble is derived, and we present an algorithm for OE image estimation from tomographic measurements. A displayable image (e.g. grid based image) is derived from the OE formulation by calculating ensemble expectations based on the PDF using the Markov chain Monte Carlo method. The approach was applied to computer-simulated 3D list-mode positron emission tomography data. The reconstruction errors for a 10 000 000 event acquisition for simulated ranged from 0.1 to 34.8%, depending on object size and sampling density. The method was also applied to experimental data and the results of the OE method were consistent with those obtained by a standard maximum-likelihood approach. The method is a new approach to representation and reconstruction of data obtained by photon-limited emission tomography measurements.

  18. Representation of photon limited data in emission tomography using origin ensembles

    Science.gov (United States)

    Sitek, A.

    2008-06-01

    Representation and reconstruction of data obtained by emission tomography scanners are challenging due to high noise levels in the data. Typically, images obtained using tomographic measurements are represented using grids. In this work, we define images as sets of origins of events detected during tomographic measurements; we call these origin ensembles (OEs). A state in the ensemble is characterized by a vector of 3N parameters Y, where the parameters are the coordinates of origins of detected events in a three-dimensional space and N is the number of detected events. The 3N-dimensional probability density function (PDF) for that ensemble is derived, and we present an algorithm for OE image estimation from tomographic measurements. A displayable image (e.g. grid based image) is derived from the OE formulation by calculating ensemble expectations based on the PDF using the Markov chain Monte Carlo method. The approach was applied to computer-simulated 3D list-mode positron emission tomography data. The reconstruction errors for a 10 000 000 event acquisition for simulated ranged from 0.1 to 34.8%, depending on object size and sampling density. The method was also applied to experimental data and the results of the OE method were consistent with those obtained by a standard maximum-likelihood approach. The method is a new approach to representation and reconstruction of data obtained by photon-limited emission tomography measurements.

  19. Representation of photon limited data in emission tomography using origin ensembles

    International Nuclear Information System (INIS)

    Sitek, A

    2008-01-01

    Representation and reconstruction of data obtained by emission tomography scanners are challenging due to high noise levels in the data. Typically, images obtained using tomographic measurements are represented using grids. In this work, we define images as sets of origins of events detected during tomographic measurements; we call these origin ensembles (OEs). A state in the ensemble is characterized by a vector of 3N parameters Y, where the parameters are the coordinates of origins of detected events in a three-dimensional space and N is the number of detected events. The 3N-dimensional probability density function (PDF) for that ensemble is derived, and we present an algorithm for OE image estimation from tomographic measurements. A displayable image (e.g. grid based image) is derived from the OE formulation by calculating ensemble expectations based on the PDF using the Markov chain Monte Carlo method. The approach was applied to computer-simulated 3D list-mode positron emission tomography data. The reconstruction errors for a 10 000 000 event acquisition for simulated ranged from 0.1 to 34.8%, depending on object size and sampling density. The method was also applied to experimental data and the results of the OE method were consistent with those obtained by a standard maximum-likelihood approach. The method is a new approach to representation and reconstruction of data obtained by photon-limited emission tomography measurements

  20. Essentials of photonics

    CERN Document Server

    Rogers, Alan; Baets, Roel

    2008-01-01

    Photons and ElectronsHistorical SketchThe Wave Nature of LightPolarizationThe Electromagnetic SpectrumEmission and Absorption ProcessesPhoton Statistics The Behaviour of Electrons LasersSummaryWave Properties of LightThe Electromagnetic SpectrumWave RepresentationElectromagnetic WavesReflection and RefractionTotal Internal ReflectionInterference of LightLight WaveguidingInterferometersDiffractionGaussian Beams and Stable Optical ResonatorsPolarization OpticsThe Polarization EllipseCrystal OpticsRetarding WaveplatesA Variable Waveplate: The Soleil-Babinet Compensator Polarizing PrismsLinear BirefringenceCircular BirefringenceElliptical BirefringencePractical Polarization EffectsPolarization AnalysisThe Form of the Jones MatricesLight and Matter Emission, Propagation, and Absorption ProcessesClassical Theory of Light Propagation in Uniform Dielectric Media Optical Dispersion Emission and Absorption of LightOptical Coherence and CorrelationIntroductionMeasure of Coherence Wiener-Khinchin TheoremDual-Beam Interfe...

  1. On the kinematics of the two-photon Cherenkov effect

    International Nuclear Information System (INIS)

    Afanas'ev, G.N.; Stepanovskij, Yu.P.

    2003-01-01

    We study the kinematics of the two-photon Cherenkov effect. In the general case, the emission angles of two photons satisfy certain inequalities and the corresponding radiation intensities are rather diffused. In special cases, when the above inequalities reduce to equalities, the emission angles of two photons are fixed and the corresponding radiation intensities should have sharp maxima at these angles. This makes easier the experimental study of the two-photon Cherenkov effect

  2. Applications of photon-in, photon-out spectroscopy with third-generation, synchrotron-radiation sources

    International Nuclear Information System (INIS)

    Lindle, D.W.; Perera, R.C.C.

    1991-01-01

    This report discusses the following topics: Mother nature's finest test probe; soft x-ray emission spectroscopy with high-brightness synchrotron radiation sources; anisotropy and polarization of x-ray emission from atoms and molecules; valence-hole fluorescence from molecular photoions as a probe of shape-resonance ionization: progress and prospects; structural biophysics on third-generation synchrotron sources; ultra-soft x-ray fluorescence-yield XAFS: an in situ photon-in, photon-out spectroscopy; and x-ray microprobe: an analytical tool for imaging elemental composition and microstructure

  3. A novel phantom design for emission tomography enabling scatter- and attenuation-''free'' single-photon emission tomography imaging

    International Nuclear Information System (INIS)

    Larsson, S.A.; Johansson, L.; Jonsson, C.; Pagani, M.; Jacobsson, H.

    2000-01-01

    A newly designed technique for experimental single-photon emission tomography (SPET) and positron emission tomography (PET) data acquisition with minor disturbing effects from scatter and attenuation has been developed. In principle, the method is based on discrete sampling of the radioactivity distribution in 3D objects by means of equidistant 2D planes. The starting point is a set of digitised 2D sections representing the radioactivity distribution of the 3D object. Having a radioactivity-related grey scale, the 2D images are printed on paper sheets using radioactive ink. The radioactive sheets can be shaped to the outline of the object and stacked into a 3D structure with air or some arbitrary dense material in between. For this work, equidistantly spaced transverse images of a uniform cylindrical phantom and of the digitised Hoffman rCBF phantom were selected and printed out on paper sheets. The uniform radioactivity sheets were imaged on the surface of a low-energy ultra-high-resolution collimator (4 mm full-width at half-maximum) of a three-headed SPET camera. The reproducibility was 0.7% and the uniformity was 1.2%. Each rCBF sheet, containing between 8.3 and 80 MBq of 99m TcO 4 - depending on size, was first imaged on the collimator and then stacked into a 3D structure with constant 12 mm air spacing between the slices. SPET was performed with the sheets perpendicular to the central axis of the camera. The total weight of the stacked rCBF phantom in air was 63 g, giving a scatter contribution comparable to that of a point source in air. The overall attenuation losses were <20%. A second SPET study was performed with 12-mm polystyrene plates in between the radioactive sheets. With polystyrene plates, the total phantom weight was 2300 g, giving a scatter and attenuation magnitude similar to that of a patient study. With the proposed technique, it is possible to obtain ''ideal'' experimental images (essentially built up by primary photons) for comparison with

  4. Sculpted light for two‐photon optogenetics using GPC

    DEFF Research Database (Denmark)

    Glückstad, Jesper

    2013-01-01

    The synergy between nanotechnology, biotechnology and photonics is spawning the emerging fields of nanobiotechnology and nano‐biophotonics. Photonic innovations already hurdle the diffraction barrier for imaging with nanoscopic resolutions. However, scientific hypothesis testing demands tools...... cellular scales. Two‐photon spatio‐temporal light engineering can be used to expand the microscopic imaging modalities available to assist this light‐driven nano‐manipulation approach. Featured in a recent issue of Nature Methods we were pioneering research in neuro‐photonics and optogenetics highly useful...

  5. True photonic band-gap mode-control in VCSEL structures

    DEFF Research Database (Denmark)

    Romstad, F.; Madsen, M.; Birkedal, Dan

    2003-01-01

    Photonic band-gap mode confinement in novel nano-structured large area VCSEL structures is confirmed by the amplified spontaneous emission spectrum. Both guide and anti-guide VCSEL structures are experimentally characterised to verify the photonic band-gap effect.......Photonic band-gap mode confinement in novel nano-structured large area VCSEL structures is confirmed by the amplified spontaneous emission spectrum. Both guide and anti-guide VCSEL structures are experimentally characterised to verify the photonic band-gap effect....

  6. Photons in a partonic transport approach

    Energy Technology Data Exchange (ETDEWEB)

    Greif, Moritz; Senzel, Florian; Greiner, Carsten [Goethe Universitaet Frankfurt, Max-von-Laue-Str. 1 60438 Frankfurt am Main (Germany)

    2015-07-01

    Partonic transport approaches have proved to be valuable tools in describing the quark-gluon plasma, created in heavy-ion collisions. In this work, first steps towards a dynamical understanding of photonproduction in expanding heavy-ion collisions are presented. Several photon production processes are included in the partonic cascade BAMPS (Boltzmann Approach to Multi-Parton Scatterings). BAMPS provides a microscopic tool to study expanding fireballs, employing a stochastic method to solve the relativistic 3+1d Boltzmann equation. Subsequently, photon spectra can be investigated, and in particular, the influence of the quark-gluon plasma phase for the elliptic flow of photons is studied.

  7. Computational Modeling of Photonic Crystal Microcavity Single-Photon Emitters

    Science.gov (United States)

    Saulnier, Nicole A.

    Conventional cryptography is based on algorithms that are mathematically complex and difficult to solve, such as factoring large numbers. The advent of a quantum computer would render these schemes useless. As scientists work to develop a quantum computer, cryptographers are developing new schemes for unconditionally secure cryptography. Quantum key distribution has emerged as one of the potential replacements of classical cryptography. It relics on the fact that measurement of a quantum bit changes the state of the bit and undetected eavesdropping is impossible. Single polarized photons can be used as the quantum bits, such that a quantum system would in some ways mirror the classical communication scheme. The quantum key distribution system would include components that create, transmit and detect single polarized photons. The focus of this work is on the development of an efficient single-photon source. This source is comprised of a single quantum dot inside of a photonic crystal microcavity. To better understand the physics behind the device, a computational model is developed. The model uses Finite-Difference Time-Domain methods to analyze the electromagnetic field distribution in photonic crystal microcavities. It uses an 8-band k · p perturbation theory to compute the energy band structure of the epitaxially grown quantum dots. We discuss a method that combines the results of these two calculations for determining the spontaneous emission lifetime of a quantum dot in bulk material or in a microcavity. The computational models developed in this thesis are used to identify and characterize microcavities for potential use in a single-photon source. The computational tools developed are also used to investigate novel photonic crystal microcavities that incorporate 1D distributed Bragg reflectors for vertical confinement. It is found that the spontaneous emission enhancement in the quasi-3D cavities can be significantly greater than in traditional suspended slab

  8. Time-resolved statistics of photon pairs in two-cavity Josephson photonics

    Energy Technology Data Exchange (ETDEWEB)

    Dambach, Simon; Kubala, Bjoern; Ankerhold, Joachim [Institute for Complex Quantum Systems and IQST, Ulm University (Germany)

    2017-06-15

    We analyze the creation and emission of pairs of highly nonclassical microwave photons in a setup where a voltage-biased Josephson junction is connected in series to two electromagnetic oscillators. Tuning the external voltage such that the Josephson frequency equals the sum of the two mode frequencies, each tunneling Cooper pair creates one additional photon in both of the two oscillators. The time-resolved statistics of photon emission events from the two oscillators is investigated by means of single- and cross-oscillator variants of the second-order correlation function g{sup (2)}(τ) and the waiting-time distribution w(τ). They provide insight into the strongly correlated quantum dynamics of the two oscillator subsystems and reveal a rich variety of quantum features of light including strong antibunching and the presence of negative values in the Wigner function. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  9. Entangled, guided photon generation in (1+1)-dimensional photonic crystals

    International Nuclear Information System (INIS)

    Sciscione, L.; Centini, M.; Sibilia, C.; Bertolotti, M.; Scalora, M.

    2006-01-01

    A scheme based on photonic crystal technology is proposed as an ultrabright source of entangled photons on a miniaturized scale. The geometry consists of a multilayer microcavity, excited by a resonant pump frequency, such that the emitted photons are guided transversally to the direction of the incident pump. The entanglement occurs in direction, frequency, and polarization, and the bandwidth of the emitted photons is of the order of 1 nm. We propose a feasible design based on Al 0.3 Ga 0.7 As/Al 2 O 3 structures and predict an emission rate 10 5 pairs per second with 100 mW pump power. These results are promising for realization of chip and future quantum computer applications

  10. Two photon versus one photon fluorescence excitation in whispering gallery mode microresonators

    International Nuclear Information System (INIS)

    Pastells, Carme; Marco, M.-Pilar; Merino, David; Loza-Alvarez, Pablo; Pasquardini, Laura; Lunelli, Lorenzo; Pederzolli, Cecilia; Daldosso, Nicola; Farnesi, Daniele; Berneschi, Simone; Righini, Giancarlo C.; Quercioli, Franco; Nunzi Conti, Gualtiero; Soria, Silvia

    2016-01-01

    We investigate the feasibility of both one photon and two photon fluorescence excitation using whispering gallery mode microresonators. We report the linear and non linear fluorescence real-time detection of labeled IgG covalently bonded to the surface of a silica whispering gallery mode resonator (WGMR). The immunoreagents have been immobilized onto the surface of the WGMR sensor after being activated with an epoxy silane and an orienting layer. The developed immunosensor presents great potential as a robust sensing device for fast and early detection of immunoreactions. We also investigate the potential of microbubbles as nonlinear enhancement platform. The dyes used in these studies are dylight800, tetramethyl rhodamine isothiocyanate, rhodamine 6G and fluorescein. All measurements were performed in a modified confocal microscope. - Highlights: • One photon fluorescence overlaps with the semiconductor pump laser gain bandwidth. • We report on the feasibility to excite two photon fluorescence in microbubble resonators. • Our functionalization process maintains a good quality factor of the microresonator.

  11. Two photon versus one photon fluorescence excitation in whispering gallery mode microresonators

    Energy Technology Data Exchange (ETDEWEB)

    Pastells, Carme; Marco, M.-Pilar [Nanobiotechnology for Diagnostics Group (Nb4Dg), IQAC-CSIC, 08034 Barcelona (Spain); CIBER de Bioingeniería, Biomateriales y Nanomedicina, 08034 Barcelona (Spain); Merino, David; Loza-Alvarez, Pablo [ICFO-Institut de Ciències Fotòniques, Castelldefels, 08860 Barcelona (Spain); Pasquardini, Laura [Fondazione Bruno Kessler, 38123 Povo, TN (Italy); Lunelli, Lorenzo [Fondazione Bruno Kessler, 38123 Povo, TN (Italy); IBF-CNR, 38123 Povo, TN (Italy); Pederzolli, Cecilia [Fondazione Bruno Kessler, 38123 Povo, TN (Italy); Daldosso, Nicola [Department of Computer Science, University of Verona, Strada le Grazie 15, 37134 Verona (Italy); Farnesi, Daniele [CNR-IFAC “Nello Carrara” Institute of Applied Physics, 50019 Sesto Fiorentino, FI (Italy); Museo Storico della Fisica e Centro Studi e Ricerche “E. Fermi”, 00184 Roma (Italy); Berneschi, Simone [CNR-IFAC “Nello Carrara” Institute of Applied Physics, 50019 Sesto Fiorentino, FI (Italy); Righini, Giancarlo C. [CNR-IFAC “Nello Carrara” Institute of Applied Physics, 50019 Sesto Fiorentino, FI (Italy); Museo Storico della Fisica e Centro Studi e Ricerche “E. Fermi”, 00184 Roma (Italy); Quercioli, Franco [CNR-INO National Institute of Optics, Sesto Fiorentino, FI (Italy); Nunzi Conti, Gualtiero [CNR-IFAC “Nello Carrara” Institute of Applied Physics, 50019 Sesto Fiorentino, FI (Italy); Soria, Silvia, E-mail: s.soria@ifac.cnr.it [CNR-IFAC “Nello Carrara” Institute of Applied Physics, 50019 Sesto Fiorentino, FI (Italy)

    2016-02-15

    We investigate the feasibility of both one photon and two photon fluorescence excitation using whispering gallery mode microresonators. We report the linear and non linear fluorescence real-time detection of labeled IgG covalently bonded to the surface of a silica whispering gallery mode resonator (WGMR). The immunoreagents have been immobilized onto the surface of the WGMR sensor after being activated with an epoxy silane and an orienting layer. The developed immunosensor presents great potential as a robust sensing device for fast and early detection of immunoreactions. We also investigate the potential of microbubbles as nonlinear enhancement platform. The dyes used in these studies are dylight800, tetramethyl rhodamine isothiocyanate, rhodamine 6G and fluorescein. All measurements were performed in a modified confocal microscope. - Highlights: • One photon fluorescence overlaps with the semiconductor pump laser gain bandwidth. • We report on the feasibility to excite two photon fluorescence in microbubble resonators. • Our functionalization process maintains a good quality factor of the microresonator.

  12. SHI induced enhancement in green emission from nanocrystalline CdS thin films for photonic applications

    International Nuclear Information System (INIS)

    Kumar, Pragati; Saxena, Nupur; Chandra, Ramesh; Gao, Kun; Zhou, Shengqiang; Agarwal, Avinash; Singh, Fouran; Gupta, Vinay; Kanjilal, D.

    2014-01-01

    Intense green emission is reported from nanocrystalline CdS thin films grown by pulsed laser deposition. The effect of ion beam induced dense electronic excitation on luminescence property of CdS films is explored under irradiation using 70 MeV 58 Ni 6+ ions. It is found that swift heavy ion beam irradiation enhances the emission intensity by an order of 1 and broadens the emission range. This feature is extremely useful to enhance the performance of different photonic devices like light emitting diodes and lasers, as well as luminescence based sensors. To examine the role of energy relaxation process of swift heavy ions in creation/annihilation of different defect levels, multi-peaks are fitted in photoluminescence spectra using a Gaussian function. The variation of contribution of different emissions in green emission with ion fluence is studied. Origin of enhancement in green emission is supported by various characterization techniques like UV–visible absorption spectroscopy, glancing angle X-ray diffraction, micro-Raman spectroscopy and transmission electron microscopy. A possible mechanism of enhanced GE due to ion beam irradiation is proposed on the basis of existing models. -- Highlights: • Room temperature green luminescence nanocrystalline CdS thin films grown by pulsed laser deposition. • Enhanced green emission by means of swift heavy ion irradiation. • Multipeak fitting of photoluminescence spectra using a Gaussian function. • Variation of area contributed by different emissions in green emission is studied with respect to ion fluence. • Mechanism of enhanced green emission is discussed based on creation/annihilation of defects due to ion beam irradiation

  13. SHI induced enhancement in green emission from nanocrystalline CdS thin films for photonic applications

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Pragati, E-mail: pkumar.phy@gmail.com [Department of Physics, Bareilly College, Shahmat Ganj Road, Bareilly 243005, Uttar Pradesh (India); Saxena, Nupur [Inter University Accelerator Centre, Aruna Asaf Ali Marg, P.O. Box 10502, New Delhi 110067 (India); Chandra, Ramesh [Institute Instrumentation Centre, Indian Institute of Technology, Roorkee 247667 (India); Gao, Kun; Zhou, Shengqiang [Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf (HZDR), P.O. Box 510119, 01314 Dresden (Germany); Agarwal, Avinash [Department of Physics, Bareilly College, Shahmat Ganj Road, Bareilly 243005, Uttar Pradesh (India); Singh, Fouran [Inter University Accelerator Centre, Aruna Asaf Ali Marg, P.O. Box 10502, New Delhi 110067 (India); Gupta, Vinay [Department of Physics and Astrophysics, Delhi University, Delhi 110007 (India); Kanjilal, D. [Inter University Accelerator Centre, Aruna Asaf Ali Marg, P.O. Box 10502, New Delhi 110067 (India)

    2014-03-15

    Intense green emission is reported from nanocrystalline CdS thin films grown by pulsed laser deposition. The effect of ion beam induced dense electronic excitation on luminescence property of CdS films is explored under irradiation using 70 MeV {sup 58}Ni{sup 6+} ions. It is found that swift heavy ion beam irradiation enhances the emission intensity by an order of 1 and broadens the emission range. This feature is extremely useful to enhance the performance of different photonic devices like light emitting diodes and lasers, as well as luminescence based sensors. To examine the role of energy relaxation process of swift heavy ions in creation/annihilation of different defect levels, multi-peaks are fitted in photoluminescence spectra using a Gaussian function. The variation of contribution of different emissions in green emission with ion fluence is studied. Origin of enhancement in green emission is supported by various characterization techniques like UV–visible absorption spectroscopy, glancing angle X-ray diffraction, micro-Raman spectroscopy and transmission electron microscopy. A possible mechanism of enhanced GE due to ion beam irradiation is proposed on the basis of existing models. -- Highlights: • Room temperature green luminescence nanocrystalline CdS thin films grown by pulsed laser deposition. • Enhanced green emission by means of swift heavy ion irradiation. • Multipeak fitting of photoluminescence spectra using a Gaussian function. • Variation of area contributed by different emissions in green emission is studied with respect to ion fluence. • Mechanism of enhanced green emission is discussed based on creation/annihilation of defects due to ion beam irradiation.

  14. Holographic photon production in heavy ion collisions

    International Nuclear Information System (INIS)

    Iatrakis, Ioannis; Kiritsis, Elias; Shen, Chun; Yang, Di-Lun

    2017-01-01

    The thermal-photon emission from strongly coupled gauge theories at finite temperature is calculated using holographic models for QCD in the Veneziano limit (V-QCD). The emission rates are then embedded in hydrodynamic simulations combined with prompt photons from hard scattering and the thermal photons from hadron gas to analyze the spectra and anisotropic flow of direct photons at RHIC and LHC. The results from different sources responsible for the thermal photons in QGP including the weakly coupled QGP (wQGP) from perturbative calculations, strongly coupled N=4 super Yang-Mills (SYM) plasma (as a benchmark for reference), and Gubser’s phenomenological holographic model are then compared. It is found that the direct-photon spectra are enhanced in the strongly coupled scenario compared with the ones in the wQGP, especially at high momenta. Moreover, both the elliptic flow and triangular flow of direct photons are amplified at high momenta for V-QCD and the SYM plasma. The results are further compared with experimental observations.

  15. Holographic photon production in heavy ion collisions

    Energy Technology Data Exchange (ETDEWEB)

    Iatrakis, Ioannis [Institute for Theoretical Physics and Center for Extreme Matter and Emergent Phenomena,Utrecht University,Leuvenlaan 4, 3584 CE Utrecht (Netherlands); Kiritsis, Elias [Crete Center for Theoretical Physics, Institute of Theoretical and Computational Physics,Department of Physics, University of Crete,71003 Heraklion (Greece); Crete Center for Quantum Complexity and Nanotechnology,Department of Physics, University of Crete,71003 Heraklion (Greece); APC, Univ Paris Diderot, Sorbonne Paris Cité, APC, UMR 7164 CNRS,F-75205 Paris (France); Shen, Chun [Department of Physics, McGill University,3600 University Street, Montreal, QC, H3A 2T8 (Canada); Yang, Di-Lun [Theoretical Research Division, Nishina Center, RIKEN, Wako,Saitama 351-0198 (Japan)

    2017-04-07

    The thermal-photon emission from strongly coupled gauge theories at finite temperature is calculated using holographic models for QCD in the Veneziano limit (V-QCD). The emission rates are then embedded in hydrodynamic simulations combined with prompt photons from hard scattering and the thermal photons from hadron gas to analyze the spectra and anisotropic flow of direct photons at RHIC and LHC. The results from different sources responsible for the thermal photons in QGP including the weakly coupled QGP (wQGP) from perturbative calculations, strongly coupled N=4 super Yang-Mills (SYM) plasma (as a benchmark for reference), and Gubser’s phenomenological holographic model are then compared. It is found that the direct-photon spectra are enhanced in the strongly coupled scenario compared with the ones in the wQGP, especially at high momenta. Moreover, both the elliptic flow and triangular flow of direct photons are amplified at high momenta for V-QCD and the SYM plasma. The results are further compared with experimental observations.

  16. In situ manipulation and characterizations using nanomanipulators inside a field emission-scanning electron microscope

    International Nuclear Information System (INIS)

    Kim, Keun Soo; Lim, Seong Chu; Lee, Im Bok; An, Key Heyok; Bae, Dong Jae; Choi, Shinje; Yoo, Jae-Eun; Lee, Young Hee

    2003-01-01

    We have used two piezoelectric nanomanipulators to manage the multiwalled carbon nanotubes (MWCNTs) within the field emission-scanning electron microscope (FE-SEM). For an easy access of a tungsten tip to MWCNTs, we prepared the tungsten tip in sharp and long tip geometry using different electrochemical etching parameters. In addition, the sample stage was tilted by 45 deg. from the normal direction of the surface to allow a better incident angle to the approaching tungsten tip. For manipulations, a nanotube or the bundles were attached at the tungsten tip using an electron beam-induced deposition (EBID). Using two manipulators, we have then fabricated a CNT-based transistor, a cross-junction of MWCNTs, and a CNT-attached atomic force microscopy tip. After these fabrications, the field emission properties of the MWCNT and junction properties of the MWCNT and the tungsten tip have been investigated. We found that the EBID approach was very useful to weld the nanostructured materials on the tungsten tip by simply irradiating the electron beam, although this sometimes increased the contact resistance by depositing hydrocarbon materials

  17. Photon emission produced by Kr+ ions bombardment of Cr and Cr2O3 targets

    International Nuclear Information System (INIS)

    Boujlaidi, A. El; Hammoum, K.; Jadoual, L.; Jourdani, R.; Ait El Fqih, M.; Aouchiche, H.; Kaddouri, A.

    2015-01-01

    The sputter induced photon spectroscopy technique was used to study the luminescence spectra of the species sputtered from chromium powder and its oxide Cr 2 O 3 , during 5 keV Kr + ions bombardment in vacuum better than 10 −7 torr. The optical spectra recorded between 350 and 470 nm exhibit discrete lines which are attributed to neutral excited atoms of chromium (Cr I lines). The experiments are also performed under 10 −5 torr ultra pure oxygen partial pressure. The results demonstrate that the measured intensities of the emitted photons are always higher in the presence of oxygen and even higher than those obtained for Cr 2 O 3 target. In the presence of oxygen vapor we assume that an oxide film is formed on the chromium surface which is responsible of the increase of photon emission. This variation in the intensities is correctly explained in the model of electron transfer processes between the excited sputtered atom and the bombarded surface. This model suggests that the structure formed on the Cr surface in the case of oxygenated chromium is closer to that of Cr 2 O 3 oxide

  18. Combined Raman and continuous-wave-excited two-photon fluorescence cell imaging

    NARCIS (Netherlands)

    Uzunbajakava, N.; Otto, Cornelis

    2003-01-01

    We demonstrate a confocal optical microscope that combines cw two-photon-excited fluorescence microscopy with confocal Raman microscopy. With this microscope fast image acquisition with fluorescence imaging can be used to select areas of interest for subsequent chemical analysis with spontaneous

  19. Single-Photon Routing for a L-Shaped Channel

    Science.gov (United States)

    Yang, Xiong; Hou, Jiao-Jiao; Wu, Chun

    2018-02-01

    We have investigated the transport properties of a single photon scattered by a two-level atom embedded in a L-shaped waveguide, which is made of two one-dimensional (1D) semi-infinite coupled-resonator waveguides (CRWs). Single photons can be directed from one CRW to the other due to spontaneous emission of the atom. The result shows that the spontaneous emission of the TLS still routes single photon from one CRW to the other; the boundary existing makes the probability of finding single photon in a CRW could reach one. Our the scheme is helpful to construct a ring quantum networks.

  20. Photonic nanowires for quantum optics

    DEFF Research Database (Denmark)

    Munsch, M.; Claudon, J.; Bleuse, J.

    Photonic nanowires (PWs) are simple dielectric structures for which a very efficient and broadband spontaneous emission (SE) control has been predicted [1]. Recently, a single photon source featuring a record high efficiency was demonstrated using this geometry [2]. Using time-resolved micro-phot...

  1. Transparency and spontaneous emission in a densely doped photonic band gap material

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Mahi R [Department of Physics and Astronomy, University of Western Ontario, London N6A 3K7 (Canada)

    2006-12-28

    The susceptibility has been calculated for a photonic crystal in the presence of spontaneous cancellation and dipole-dipole interaction. The crystal is densely doped with an ensemble of four-level nano-particles in Y-type configuration. Probe and a pump laser fields are applied to manipulate the absorption coefficient of the system. The expression of the susceptibility has been calculated in the linear response regime of the probe field but nonlinear terms are included for the pump field. It is found that in the presence of spontaneous emission cancellation there is an increase in the height of the two absorption peaks however the phenomenon of electromagnetically induced transparency (EIT) is not affected. On the other hand, there is a change in the height and location of the two peaks in the presence of dipole-dipole interactions. For certain values the particle density of the system can be switched from the EIT state to the non-EIT state. It is also found that when the resonance energies for two spontaneous emission channels lie close to the band edge, the EIT phenomenon disappears.

  2. Secondary electron images obtained with a standard photoelectron emission microscope set-up

    International Nuclear Information System (INIS)

    Benka, Oswald; Zeppenfeld, Peter

    2005-01-01

    The first results of secondary electron images excited by 3-4.3 keV electrons are presented. The images are obtained with a standard FOCUS-PEEM set-up equipped with an imaging energy filter (IEF). The electron gun was mounted on a standard PEEM entrance flange at an angle of 25 deg. with respect to the sample surface. A low extraction voltage of 500 V was used to minimize the deflection of the electron beam by the PEEM extraction electrode. The secondary electron images are compared to photoelectron images excited by a standard 4.9 eV UV lamp. In the case of a Cu pattern on a Si substrate it is found that the lateral resolution without the IEF is about the same for electron and photon excitation but that the relative electron emission intensities are very different. The use of the IEF reduces the lateral resolution. Images for secondary electron energies between eV 1 and eV 2 were obtained by setting the IEF to -V 1 and -V 2 ∼-(V 1 +5V) potentials and taking the difference of both images. Images up to 100 eV electron energies were recorded. The material contrast obtained in these difference images is discussed in terms of a secondary electron and photoelectron emission model and secondary electron energy spectra measured with a LEED-Auger spectrometer

  3. First images from the Stanford tabletop scanning soft x-ray microscope

    International Nuclear Information System (INIS)

    Trail, J.A.; Byer, R.L.

    1988-01-01

    The authors have constructed a scanning soft x-ray microscope which uses a laser-produced plasma as the soft x-ray source and normal incidence multilayer coated mirrors in a Schwarzschild configuration as the focusing optics. The microscope operates at a wavelength of 140 angstrom, has a spatial resolution of 0.5 μm, and has a soft x-ray photon flux through the focus of 10 4 s -1 when operated with only 170 mW of average laser power. The microscope is compact; the complete system, including the laser, fits on a single optical table. In this paper they describe the microscope and present images of metallic microstructures

  4. Microscopic Perspective on Photovoltaic Reciprocity in Ultrathin Solar Cells.

    Science.gov (United States)

    Aeberhard, Urs; Rau, Uwe

    2017-06-16

    The photovoltaic reciprocity theory relates the electroluminescence spectrum of a solar cell under applied bias to the external photovoltaic quantum efficiency of the device as measured at short circuit conditions. Its derivation is based on detailed balance relations between local absorption and emission rates in optically isotropic media with nondegenerate quasiequilibrium carrier distributions. In many cases, the dependence of density and spatial variation of electronic and optical device states on the point of operation is modest and the reciprocity relation holds. In nanostructure-based photovoltaic devices exploiting confined modes, however, the underlying assumptions are no longer justifiable. In the case of ultrathin absorber solar cells, the modification of the electronic structure with applied bias is significant due to the large variation of the built-in field. Straightforward use of the external quantum efficiency as measured at short circuit conditions in the photovoltaic reciprocity theory thus fails to reproduce the electroluminescence spectrum at large forward bias voltage. This failure is demonstrated here by numerical simulation of both spectral quantities at normal incidence and emission for an ultrathin GaAs p-i-n solar cell using an advanced quantum kinetic formalism based on nonequilibrium Green's functions of coupled photons and charge carriers. While coinciding with the semiclassical relations under the conditions of their validity, the theory provides a consistent microscopic relationship between absorption, emission, and charge carrier transport in photovoltaic devices at arbitrary operating conditions and for any shape of optical and electronic density of states.

  5. Single Photon Sources in Silicon Carbide

    International Nuclear Information System (INIS)

    Brett Johnson

    2014-01-01

    Single photon sources in semiconductors are highly sought after as they constitute the building blocks of a diverse range of emerging technologies such as integrated quantum information processing, quantum metrology and quantum photonics. In this presentation, we show the first observation of single photon emission from deep level defects in silicon carbide (SiC). The single photon emission is photo-stable at room temperature and surprisingly bright. This represents an exciting alternative to diamond color centers since SiC possesses well-established growth and device engineering protocols. The defect is assigned to the carbon vacancy-antisite pair which gives rise to the AB photoluminescence lines. We discuss its photo-physical properties and their fabrication via electron irradiation. Preliminary measurements on 3C SiC nano-structures will also be discussed. (author)

  6. Photon echo with a few photons in two-level atoms

    International Nuclear Information System (INIS)

    Bonarota, M; Dajczgewand, J; Louchet-Chauvet, A; Le Gouët, J-L; Chanelière, T

    2014-01-01

    To store and retrieve signals at the single photon level, various photon echo schemes have resorted to complex preparation steps involving ancillary shelving states in multi-level atoms. For the first time, we experimentally demonstrate photon echo operation at such a low signal intensity without any preparation step, which allows us to work with mere two-level atoms. This simplified approach relies on the so-coined ‘revival of silenced echo’ (ROSE) scheme. Low noise conditions are obtained by returning the atoms to the ground state before the echo emission. In the present paper we manage ROSE in photon counting conditions, showing that very strong control fields can be compatible with extremely weak signals, making ROSE consistent with quantum memory requirements. (paper)

  7. Studies of left ventricular volume estimation from single photon emission computed tomography

    International Nuclear Information System (INIS)

    Hiraki, Yoshio; Shimizu, Mitsuharu; Joja, Ikuo; Aono, Kaname; Yanagi, Hidekiyo; Indo, Haruaki; Seno, Yoshimasa; Teramoto, Shigeru; Nagaya, Isao.

    1988-01-01

    We studied the comparative accuracy of 99m Tc cardiac blood pool Single Photon Emission Computed Tomography (SPECT) for the measurement of left ventricular volume in 20 patients undergoing SPECT and single plane contrast left ventriculography (LVG). Left ventricular volume was calculated based on the total number of voxels in left ventricle. End-diastolic left ventricular volume (EDV) and end-systolic left ventricular volume (ESV) calculated from SPECT were compared with those from LVG. SPECT volume values showed a high degree of correlation with those by LVG (r = 0.923 for EDV, r = 0.903 for ESV). We appreciated the usefulness and accuracy of SPECT in measuring left ventricular volume because of its three-dimensional information. (author)

  8. Coherent control of spontaneous emission near a photonic band edge

    International Nuclear Information System (INIS)

    Woldeyohannes, Mesfin; John, Sajeev

    2003-01-01

    We demonstrate the coherent control of spontaneous emission for a three-level atom located within a photonic band gap (PBG) material, with one resonant frequency near the edge of the PBG. Spontaneous emission from the three-level atom can be totally suppressed or strongly enhanced depending on the relative phase between the steady-state control laser coupling the two upper levels and the pump laser pulse used to create an excited state of the atom in the form of a coherent superposition of the two upper levels. Unlike the free-space case, the steady-state inversion of the atomic system is strongly dependent on the externally prescribed initial conditions. This non-zero steady-state population is achieved by virtue of the localization of light in the vicinity of the emitting atom. It is robust to decoherence effects provided that the Rabi frequency of the control laser field exceeds the rate of dephasing interactions. As a result, such a system may be relevant for a single-atom, phase-sensitive optical memory device on the atomic scale. The protected electric dipole within the PBG provides a basis for a qubit to encode information for quantum computations. A detailed literature survey on the nature, fabrication and applications of PBG materials is presented to provide context for this research. (phd tutorial)

  9. Trace Element Mapping of a Biological Specimen by a Full-Field X-ray Fluorescence Imaging Microscope with a Wolter Mirror

    International Nuclear Information System (INIS)

    Hoshino, Masato; Yamada, Norimitsu; Ishino, Toyoaki; Namiki, Takashi; Watanabe, Norio; Aoki, Sadao

    2007-01-01

    A full-field X-ray fluorescence imaging microscope with a Wolter mirror was applied to the element mapping of alfalfa seeds. The X-ray fluorescence microscope was built at the Photon Factory BL3C2 (KEK). X-ray fluorescence images of several growing stages of the alfalfa seeds were obtained. X-ray fluorescence energy spectra were measured with either a solid state detector or a CCD photon counting method. The element distributions of iron and zinc which were included in the seeds were obtained using a photon counting method

  10. Design and performance of the 2-ID-B scanning x-ray microscope

    International Nuclear Information System (INIS)

    McNulty, I.

    1998-01-01

    We have constructed a high resolution scanning x-ray microscope at the 2-ID-B beamline at the Advanced Photon Source for 1-4 keV x-ray imaging and microspectroscopy experiments. The microscope uses a Fresnel zone plate to focus coherent x-ray undulator radiation to a 150 nm focal spot on a sample. The spectral flux in the focus is 10 8 ph/s/0.1% BW. X-ray photons transmitted by the sample are detected by an avalanche photodiode as the sample is scanned to form an absorption image. The sample stage has both coarse and fine translation axes for raster scanning and a rotation axis for microtomography experiments. The incident x-ray beam energy can also be scanned via the 2-ID-B monochromator while the sample is kept in focus to record spatially resolved absorption spectra. We have measured the performance of the instrument with various test objects. The microscope hardware, software, and performance are discussed in this paper

  11. Physical factors affecting single photon emission computed tomography (SPECT) applied in nuclear medicine

    International Nuclear Information System (INIS)

    Farag, H.I.; Khalil, W.A.; Hassan, R.A.

    2003-01-01

    many physical factors degrade single photon emission computed tomography (SPECT) images both qualitatively and quantitatively. Physical properties important for the assessment of the potential of emission computed tomography implemented by collimated detector systems include sensitivity, statistical and angular sampling requirements, attenuation compensation, resolution, uniformity, and multisection design constraints. SPECT has highlighted the used to improve gamma camera performance. Flood field nonuniformity is translated into tomographic the need to improve gamma camera performance. Flood field nonuniformity is translated into tomographic images as major artifacts because it distorts the data obtained at each projection. Also, poor energy resolution translates directly into degraded spatial resolution through reduced ability to reject scattered photons on the basic of pluses height analysis. The aim of this work is study the different and most important acquisition and processing parameters, which affect the quality of the SPECT images. The present study investigates the various parameters effecting SPECT images and experimental results demonstrate that: daily uniformity checks and evaluation are essential to ensure that the SPECT system is working properly. The Core used in the reconstruction process could be correct to avoid data misalignment. 60 mumblers of views gave the best image quality, rather than 20 or 30 views. Time per view (TPV) 30 or 20 sec gave a good image quality, rather than high-resolution collimator, is recommended in order to provide good spatial resolution. On the other hand patient motion could cause serious reconstruction artifacts. A cine display is recommended to identify movement artifacts. In the case of matrix size, matrix 128x128 give the best resolution than matrix 64x64. Energy window width, 15% compared with the standard 20% improved the resolution. Butter worth filter (cut off 0.57 cyc/cm with order 6 ) give the best resolution

  12. Field Emission Scanning Electron Microscope (FESEM) Facility in BTI

    International Nuclear Information System (INIS)

    Cik Rohaida Che Hak; Foo, C.T.; Nor Azillah Fatimah Othman

    2015-01-01

    Field Emission Scanning Electron Microscope (FE-SEM) provides ultra-high resolution imaging at low accelerating voltages and small working distances. The GeminisSEM 500, a new FESEM imaging facility will be installed soon in MTEC, BTI. It provides resolution of the images is as low as 0.6 nm at 15 kV and 1.2 nm at 1 kV, allowing examination of the top surface of nano powders, nano film and nano fiber in the wide range of applications such as mineralogy, ceramics, polymer, metallurgy, electronic devices, chemistry, physics and life sciences. This system is equipped with several detectors to detect various signals such as secondary electrons (SE) detector for topographic information and back-scattered electrons (BSE) detector for materials composition contrast. Energy dispersive x-ray spectroscopy (EDS) with detector energy resolution of < 129 eV and detection limit in the range of 1000-3000 ppm coupled with FE-SEM is used to determine the chemical composition of micro-features including boron (B) to uranium (U). Wavelength dispersive x-ray spectroscopy (WDS) which has detector resolution of 2-20 eV and detection limit of 30-300 ppm coupled with FE-SEM is used to detect elements that cannot be resolved with EDS. The ultra-high resolution imaging combined with the high sensitivity WDS helps to resolve the thorium and rare earth elemental analysis. (author)

  13. I-123 iomazenil single photon emission computed tomography for detecting loss of neuronal integrity in patients with traumatic brain injury

    OpenAIRE

    Abiko, Kagari; Ikoma, Katsunori; Shiga, Tohru; Katoh, Chietsugu; Hirata, Kenji; Kuge, Yuji; Kobayashi, Kentaro; Tamaki, Nagara

    2017-01-01

    Background Traumatic brain injury (TBI) causes brain dysfunction in many patients. Using C-11 flumazenil (FMZ) positron emission tomography (PET), we have detected and reported the loss of neuronal integrity, leading to brain dysfunction in TBI patients. Similarly to FMZ PET, I-123 iomazenil (IMZ) single photon emission computed tomography (SPECT) is widely used to determine the distribution of the benzodiazepine receptor (BZR) in the brain cortex. The purpose of this study is to examine whet...

  14. Single photon emission computed tomography in lumbar degenerative spondylolisthesis

    International Nuclear Information System (INIS)

    Ito, S.; Muro, T.; Eisenstein, S.

    1998-01-01

    Analysis of single photon emission computed tomographic images and plain X-ray films of the lumbar vertebrae was performed in 15 patients with lumbar spondylosis and 15 patients with lumbar degenerative spondylolisthesis. The facet joint and osteophyte images were observed in particular, and the slipping ratio of spondylolisthetic vertebrae was determined. The slipping ratio of degenerative spondylolisthesis ranged from 11.8 % to 22.3 %. Hot uptake of 99mTc-HMDP by both L4-5 facet joints was significantly greater in the patients with degenerative spondylolisthesis than in those with lumbar spondylosis. The hot uptake by the osteophytes in lumbar spondylosis was nearly uniform among the three inferior segments, L3-4, L4-5 and L5-S, but was localized to the spondylolisthetic vertebrae, L4-5, or L5-S, in the patients with spondylolisthesis. Half of the osteophytes with hot uptake were assigned to the 3rd degree of Nathan's grading. It was suggested that stress was localized to the slipping vertebrae and their facet joints in patients with lumbar degenerative spondylolisthesis. (author)

  15. Single-Photon Emission Computed Tomography (SPECT) in childhood epilepsy

    International Nuclear Information System (INIS)

    Gulati, Sheffali; Kalra, Veena; Bal, C.S.

    2000-01-01

    The success of epilepsy surgery is determined strongly by the precise location of the epileptogenic focus. The information from clinical electrophysiological data needs to be strengthened by functional neuroimaging techniques. Single photon emission computed tomography (SPECT) available locally has proved useful as a localising investigation. It evaluates the regional cerebral blood flow and the comparison between ictal and interictal blood flow on SPECT has proved to be a sensitive nuclear marker for the site of seizure onset. Many studies justify the utility of SPECT in localising lesions to possess greater precision than interictal scalp EEG or anatomic neuroimaging. SPECT is of definitive value in temporal lobe epilepsy. Its role in extratemporal lobe epilepsy is less clearly defined. It is useful in various other generalized and partial seizure disorders including epileptic syndromes and helps in differentiating pseudoseizures from true seizures. The need for newer radiopharmaceutical agents with specific neurochemical properties and longer shelf life are under investigation. Subtraction ictal SPECT co-registered to MRI is a promising new modality. (author)

  16. Orthopedic applications of single photon emission computed Tomographic bone scanning

    International Nuclear Information System (INIS)

    Collier, B.D.

    1987-01-01

    When compared with planar bone scanning, single photon emission computed tomography (SPECT) has technical advantages of potential diagnostic significance. Planar imaging often superimposes substantial underlying or overlying activity on the bony structure of medical interest. SPECT, however, can be used to remove such unwanted activity. For example, in the hip the acetabulum extends downwards behind the femoral head. Therefore when using planar bone scanning techniques, the photon-deficient defect typical of avascular necrosis (AVN) of the femoral had may be obscured by activity originating in the underlying acetabulum. By using SPECT, underlying and overlying distributions of activity can be separated into sequential tomographic planes. For this reason SPECT facilitates the detection of AVN of the femoral head. When referring a patient without a history of malignancy for bone scanning, the orthopaedic surgeon usually has a specific clinical question involving a limited portion of the skeleton. Orthopaedic surgeons at their institution commonly use bone scanning to clarify the cause of back, hip or knee pain; to determine with a physiological test the significance of radiographic findings; and to establish the extent of disease at symptomatic skeletal sites such as the three compartments of the knee. In instances such as these, when clinical concern is limited to a specific anatomical region, a bone scan procedure that includes SPECT imaging of only a portion of the skeleton is appropriate. To date, SPECT of the skeletal system has most frequently been used to evaluate patients with pain the larger joints and bony structures such as the lumbar spine, hips, knees, or temporomandibular joints (TMJ)

  17. Dynamic emission tomography of regional cerebral blood flow

    International Nuclear Information System (INIS)

    Lassen, N.A.

    1984-01-01

    The author reviews three tomographic methods for measuring the regional cerebral blood flow: single photon transmission tomography; dual photon emission tomography; and single photon emission tomography. The latter technique is discussed in detail. (Auth.)

  18. Photonic crystal and photonic quasicrystal patterned in PDMS surfaces and their effect on LED radiation properties

    Energy Technology Data Exchange (ETDEWEB)

    Suslik, Lubos [Dept. of Physics, Faculty of Electrical Engineering, University of Zilina, Univerzitna 1, 010 26, Zilina (Slovakia); Pudis, Dusan, E-mail: pudis@fyzika.uniza.sk [Dept. of Physics, Faculty of Electrical Engineering, University of Zilina, Univerzitna 1, 010 26, Zilina (Slovakia); Goraus, Matej [Dept. of Physics, Faculty of Electrical Engineering, University of Zilina, Univerzitna 1, 010 26, Zilina (Slovakia); Nolte, Rainer [Fakultät für Maschinenbau FG Lichttechnik Ilmenau University of Technology, Ilmenau (Germany); Kovac, Jaroslav [Inst. of Electronics and Photonics, Slovak University of Technology, Ilkovicova 3, 812 19, Bratislava (Slovakia); Durisova, Jana; Gaso, Peter [Dept. of Physics, Faculty of Electrical Engineering, University of Zilina, Univerzitna 1, 010 26, Zilina (Slovakia); Hronec, Pavol [Inst. of Electronics and Photonics, Slovak University of Technology, Ilkovicova 3, 812 19, Bratislava (Slovakia); Schaaf, Peter [Chair Materials for Electronics, Institute of Materials Engineering and Institute of Micro- and Nanotechnologies MacroNano, TU Ilmenau, Gustav-Kirchhoff-Str. 5, 98693 Ilmenau (Germany)

    2017-02-15

    Graphical abstract: Photonic quasicrystal patterned in the surface of polydimethylsiloxane membrane (left) and radiation pattern of light emitting diode with patterned membrane applied in the surface (right). - Highlights: • We presented fabrication technique of PDMS membranes with patterned surface by photonic crystal (PhC) and photonic quasi-crystal (PQC). • Presented technique is effective for preparation PhC and PQC PDMS membranes easily implementing in the LED chip. • From the goniophotometer measurements, the membranes document effective angular emission due to the diffraction on patterned surfaces. • 12 fold symmetry PQC structure shows homogeneous radiation pattern, while the 2 fold symmetry of square PhC shows evident diffraction lobes. - Abstract: We present results of fabrication and implementation of thin polydimethylsiloxane (PDMS) membranes with patterned surface for the light emitting diode (LED). PDMS membranes were patterned by using the interference lithography in combination with embossing technique. Two-dimensional photonic crystal and photonic quasicrystal structures with different period were patterned in the surface of thin PDMS membranes with depth up to 550 nm. Patterned PDMS membranes placed on the LED chip effectively diffracted light and increased angular emission of LED radiation pattern. We presented effective technique for fabrication of patterned PDMS membranes, which could modify the emission properties of optoelectronic devices and can be applied directly on surface LEDs and small optical devices.

  19. Interference experiment with asymmetric double slit by using 1.2-MV field emission transmission electron microscope.

    Science.gov (United States)

    Harada, Ken; Akashi, Tetsuya; Niitsu, Kodai; Shimada, Keiko; Ono, Yoshimasa A; Shindo, Daisuke; Shinada, Hiroyuki; Mori, Shigeo

    2018-01-17

    Advanced electron microscopy technologies have made it possible to perform precise double-slit interference experiments. We used a 1.2-MV field emission electron microscope providing coherent electron waves and a direct detection camera system enabling single-electron detections at a sub-second exposure time. We developed a method to perform the interference experiment by using an asymmetric double-slit fabricated by a focused ion beam instrument and by operating the microscope under a "pre-Fraunhofer" condition, different from the Fraunhofer condition of conventional double-slit experiments. Here, pre-Fraunhofer condition means that each single-slit observation was performed under the Fraunhofer condition, while the double-slit observations were performed under the Fresnel condition. The interference experiments with each single slit and with the asymmetric double slit were carried out under two different electron dose conditions: high-dose for calculation of electron probability distribution and low-dose for each single electron distribution. Finally, we exemplified the distribution of single electrons by color-coding according to the above three types of experiments as a composite image.

  20. Painful spondylolysis or spondylolisthesis studied by radiography and single-photon emission computed tomography

    International Nuclear Information System (INIS)

    Collier, B.D.; Johnson, R.P.; Carrera, G.F.

    1985-01-01

    Planar bone scintigraphy (PBS) and single-photon emission computed tomography (SPECT) were compared in 19 adults with radiographic evidence of spondylolysis and/or spondylolisthesis. SPECT was more sensitive than PBS when used to identify symptomatic patients and sites of painful defects in the pars interarticularis. In addition, SPECT allowed more accurate localization than PBS. In 6 patients, spondylolysis or spondylolisthesis was unrealted to low back pain, and SPECT images of the posterior neural arch were normal. The authors conclude that when spondylolysis or spondylolisthesis is the cause of low back pain, pars defects are frequently heralded by increased scintigraphic activity which is best detected and localized by SPECT

  1. Painful spondylolysis or spondylolisthesis studied by radiography and single-photon emission computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Collier, B.D.; Johnson, R.P.; Carrera, G.F.; Meyer, G.A.; Schwab, J.P.; Flatley, T.J.; Isitman, A.T.; Hellman, R.S.; Zielonka, J.S.; Knobel, J.

    1985-01-01

    Planar bone scintigraphy (PBS) and single-photon emission computed tomography (SPECT) were compared in 19 adults with radiographic evidence of spondylolysis and/or spondylolisthesis. SPECT was more sensitive than PBS when used to identify symptomatic patients and sites of painful defects in the pars interarticularis. In addition, SPECT allowed more accurate localization than PBS. In 6 patients, spondylolysis or spondylolisthesis was unrealted to low back pain, and SPECT images of the posterior neural arch were normal. The authors conclude that when spondylolysis or spondylolisthesis is the cause of low back pain, pars defects are frequently heralded by increased scintigraphic activity which is best detected and localized by SPECT.

  2. Improving the resolution in soft X-ray emission spectrometers through photon-counting using an Electron Multiplying CCD

    International Nuclear Information System (INIS)

    Hall, D J; Soman, M; Tutt, J; Murray, N; Holland, A; Schmitt, T; Raabe, J; Strocov, V N; Schmitt, B

    2012-01-01

    In 2007, a study of back-illuminated Charge-Coupled Devices (CCDs) for soft X-ray photon detection demonstrated the improvements that could be brought over more traditional micro-channel plate detectors for X-ray spectrometers based on diffraction gratings and position sensitive detectors. Whilst the spatial resolution was reported to be improved dramatically, an intrinsic limit of approximately 25 micrometers was found due to the spreading of the charge cloud generated in the CCD across several pixels. To overcome this resolution limit, it is necessary to move away from the current integrated imaging methods and consider a photon-counting approach, recording the photon interaction locations to the sub-pixel level. To make use of photon-counting techniques it is important that the individual events are separable. To maintain the throughput of the spectrometer for high intensity lines, higher frame rates and therefore higher readout speeds are required. With CCD based systems, the increased noise at high readout speeds can limit the photon-counting performance. The Electron-Multiplying CCD shares a similar architecture with the standard CCD but incorporates a g ain register . This novel addition allows controllable gain to be applied to the signal before the read noise is introduced, therefore allowing individual events to be resolved above the noise even at much higher readout rates. In the past, the EM-CCD has only been available with imaging areas too small to be practical in soft X-ray emission spectrometers. The current drive for large area Electron-Multiplying CCDs is opening this technology to new photon-counting applications, requiring in-depth analysis of the processes and techniques involved. Early results indicate that through the introduction of photon-counting techniques the resolution in such systems can be dramatically improved.

  3. Assessment of left ventricular function by electrocardiogram-gated myocardial single photon emission computed tomography using quantitative gated single photon emission computed tomography software

    International Nuclear Information System (INIS)

    Morita, Koichi; Adachi, Itaru; Konno, Masanori

    1999-01-01

    Electrocardiogram (ECG)-gated myocardial single photon emission computed tomography (SPECT) can assess left ventricular (LV) perfusion and function easily using quantitative gated SPECT (QGS) software. ECG-gated SPECT was performed in 44 patients with coronary artery disease under post-stress and resting conditions to assess the values of LV functional parameters, by comparison to LV ejection fraction derived from gated blood pool scan and myocardial characteristics. A good correlation was obtained between ejection fraction using QGS and that using cardiac blood pool scan (r=0.812). Some patients with myocardial ischemia had lower ejection fraction under post-stress compared to resting conditions, indicating post-stress LV dysfunction. LV wall motion and wall thickening were significantly impaired in ischemic and infarcted myocardium, and the degree of abnormality in the infarcted areas was greater than in the ischemia area. LV functional parameters derived using QGS were useful to assess post-stress LV dysfunction and myocardial viability. In conclusion, ECG-gated myocardial SPECT permits simultaneous quantitative assessment of myocardial perfusion and function. (author)

  4. Highly efficient photonic nanowire single-photon sources for quantum information applications

    DEFF Research Database (Denmark)

    Gregersen, Niels; Claudon, J.; Munsch, M.

    2013-01-01

    to a collection efficiency of only 1-2 %, and efficient light extraction thus poses a major challenge in SPS engineering. Initial efforts to improve the efficiency have exploited cavity quantum electrodynamics (cQED) to efficiently couple the emitted photons to the optical cavity mode. An alternative approach......Within the emerging field of optical quantum information processing, the current challenge is to construct the basic building blocks for the quantum computing and communication systems. A key component is the singlephoton source (SPS) capable of emitting single photons on demand. Ideally, the SPS...... must feature near-unity efficiency, where the efficiency is defined as the number of detected photons per trigger, the probability g(2)(τ=0) of multi-photon emission events should be 0 and the emitted photons are required to be indistinguishable. An optically or electrically triggered quantum light...

  5. The photonic nanowire: an emerging platform for highly efficient single-photon sources for quantum information applications

    DEFF Research Database (Denmark)

    Gregersen, Niels; Munsch, Mathieu; Malik, Nitin S.

    2013-01-01

    Efficient coupling between a localized quantum emitter and a well defined optical channel represents a powerful route to realize single-photon sources and spin-photon interfaces. The tailored fiber-like photonic nanowire embedding a single quantum dot has recently demonstrated an appealing...... potential. However, the device requires a delicate, sharp needle-like taper with performance sensitive to minute geometrical details. To overcome this limitation we demonstrate the photonic trumpet, exploiting an opposite tapering strategy. The trumpet features a strongly Gaussian far-field emission...

  6. Enhancement of thermal photon production in event-by-event hydrodynamics

    International Nuclear Information System (INIS)

    Chatterjee, Rupa; Holopainen, Hannu; Renk, Thorsten; Eskola, Kari J.

    2011-01-01

    Thermal photon emission is widely believed to reflect properties of the earliest, hottest evolution stage of the medium created in ultrarelativistic heavy-ion collisions. Previous computations of photon emission have been carried out using a hydrodynamical medium description with smooth, averaged initial conditions. Recently, more sophisticated hydrodynamical models that calculate observables by averaging over many evolutions with event-by-event fluctuating initial conditions (ICs) have been developed. Given their direct connection to the early time dynamics, thermal photon emission appears to be an ideal observable to probe fluctuations in the medium initial state. In this work, we demonstrate that including fluctuations in the ICs may lead to an enhancement of the thermal photon yield of about a factor of 2 in the region 2 T <4 GeV/c (where thermal photon production dominates the direct photon yield) compared to a scenario using smooth, averaged ICs. Consequently, a much better agreement with PHENIX data is found. This can be understood in terms of the strong temperature dependence of thermal photon production, translating into a sensitivity to the presence of hotspots in an event and thus establishing thermal photons as a suitable probe to characterize IC fluctuations.

  7. Visualization of portal venous system by single photon emission CT

    Energy Technology Data Exchange (ETDEWEB)

    Kashiwagi, T; Ikawa, T; Azuma, M; Matsuda, H; Yoshioka, H; Mitsutani, N; Koizumi, T

    1987-03-01

    Single photon emission CT (SPECT) was performed for the intra-abdominal blood pool with /sup 99m/Tc autologous red blood cells (RBC) in 15 patients with liver cirrhosis. Twenty mCi of /sup 99m/Tc-RBC labeled by in vivo technique were administered intravenously and tomographic imaging of the intra-abdominal vascular blood pool was performed as follows. For each subject, 64 views were obtained over 360 deg of elliptic rotation at 30 seconds per view using a high resolution low energy parallel-hole collimator. Portal vein and portosystemic collaterals were clearly observed in coronal images. In 12 of 15 patients, portal vein was delineated. Portosystemic collaterals such as coronary vein, splenorenal shunt and umbilical vein were also shown in 12 patients. These images were consistent with images obtained by scintiphotosplenoportography or arterial portography. Therefore, it is considered that SPECT study for the intra-abdominal blood pool is clinically very useful for the diagnosis of abnormality of portal venous system in portal hypertension.

  8. Anti-3-[(18)F]FACBC positron emission tomography-computerized tomography and (111)In-capromab pendetide single photon emission computerized tomography-computerized tomography for recurrent prostate carcinoma: results of a prospective clinical trial.

    Science.gov (United States)

    Schuster, David M; Nieh, Peter T; Jani, Ashesh B; Amzat, Rianot; Bowman, F Dubois; Halkar, Raghuveer K; Master, Viraj A; Nye, Jonathon A; Odewole, Oluwaseun A; Osunkoya, Adeboye O; Savir-Baruch, Bital; Alaei-Taleghani, Pooneh; Goodman, Mark M

    2014-05-01

    We prospectively evaluated the amino acid analogue positron emission tomography radiotracer anti-3-[(18)F]FACBC compared to ProstaScint® ((111)In-capromab pendetide) single photon emission computerized tomography-computerized tomography to detect recurrent prostate carcinoma. A total of 93 patients met study inclusion criteria who underwent anti-3-[(18)F]FACBC positron emission tomography-computerized tomography plus (111)In-capromab pendetide single photon emission computerized tomography-computerized tomography for suspected recurrent prostate carcinoma within 90 days. Reference standards were applied by a multidisciplinary board. We calculated diagnostic performance for detecting disease. In the 91 of 93 patients with sufficient data for a consensus on the presence or absence of prostate/bed disease anti-3-[(18)F]FACBC had 90.2% sensitivity, 40.0% specificity, 73.6% accuracy, 75.3% positive predictive value and 66.7% negative predictive value compared to (111)In-capromab pendetide with 67.2%, 56.7%, 63.7%, 75.9% and 45.9%, respectively. In the 70 of 93 patients with a consensus on the presence or absence of extraprostatic disease anti-3-[(18)F]FACBC had 55.0% sensitivity, 96.7% specificity, 72.9% accuracy, 95.7% positive predictive value and 61.7% negative predictive value compared to (111)In-capromab pendetide with 10.0%, 86.7%, 42.9%, 50.0% and 41.9%, respectively. Of 77 index lesions used to prove positivity histological proof was obtained in 74 (96.1%). Anti-3-[(18)F]FACBC identified 14 more positive prostate bed recurrences (55 vs 41) and 18 more patients with extraprostatic involvement (22 vs 4). Anti-3-[(18)F]FACBC positron emission tomography-computerized tomography correctly up-staged 18 of 70 cases (25.7%) in which there was a consensus on the presence or absence of extraprostatic involvement. Better diagnostic performance was noted for anti-3-[(18)F]FACBC positron emission tomography-computerized tomography than for (111)In-capromab pendetide single

  9. Brain perfusion single photon emission computed tomography in children after acute encephalopathy

    International Nuclear Information System (INIS)

    Kurihara, Mana; Nakae, Yoichiro; Kohagizawa, Toshitaka; Eto, Yoshikatsu

    2005-01-01

    We studied single photon emission computed tomography (SPECT) of 15 children with acute encephalopathy after more than 1 year from the onset, using technetium-99 m-L, L-ethyl cystinate dimer ( 99m Tc-ECD) and a three-dementional stereotaxic region of interest template. Regional cerebral blood flow was evaluated and divided in three groups according to the severity of disability: absent or mild, moderate, and severe. There was no abnormality on SPECT in the patients without disability or with mild disability. Diffuse hypoperfusion was shown in the groups with moderate and severe disability. The patients with severe disability showed hypoperfusion in the pericallosal, frontal and central areas which was more pronounced than in the patients with moderate disability. (author)

  10. Bose-Einstein condensation of photons from the thermodynamic limit to small photon numbers

    Science.gov (United States)

    Nyman, Robert A.; Walker, Benjamin T.

    2018-03-01

    Photons can come to thermal equilibrium at room temperature by scattering multiple times from a fluorescent dye. By confining the light and dye in a microcavity, a minimum energy is set and the photons can then show Bose-Einstein condensation. We present here the physical principles underlying photon thermalization and condensation, and review the literature on the subject. We then explore the 'small' regime where very few photons are needed for condensation. We compare thermal equilibrium results to a rate-equation model of microlasers, which includes spontaneous emission into the cavity, and we note that small systems result in ambiguity in the definition of threshold.

  11. The Statistics of Emission and Detection of Neutrons and Photons from Fissile Samples for Safeguard Applications

    International Nuclear Information System (INIS)

    Enqvist, Andreas

    2008-03-01

    One particular purpose of nuclear safeguards, in addition to accounting for known materials, is the detection, identifying and quantifying unknown material, to prevent accidental and clandestine transports and uses of nuclear materials. This can be achieved in a non-destructive way through the various physical and statistical properties of particle emission and detection from such materials. This thesis addresses some fundamental aspects of nuclear materials and the way they can be detected and quantified by such methods. Factorial moments or multiplicities have long been used within the safeguard area. These are low order moments of the underlying number distributions of emission and detection. One objective of the present work was to determine the full probability distribution and its dependence on the sample mass and the detection process. Derivation and analysis of the full probability distribution and its dependence on the above factors constitutes the first part of the thesis. Another possibility of identifying unknown samples lies in the information in the 'fingerprints' (pulse shape distribution) left by a detected neutron or photon. A study of the statistical properties of the interaction of the incoming radiation (neutrons and photons) with the detectors constitutes the second part of the thesis. The interaction between fast neutrons and organic scintillation detectors is derived, and compared to Monte Carlo simulations. An experimental approach is also addressed in which cross correlation measurements were made using liquid scintillation detectors. First the dependence of the pulse height distribution on the energy and collision number of an incoming neutron was derived analytically and compared to numerical simulations. Then an algorithm was elaborated which can discriminate neutron pulses from photon pulses. The resulting cross correlation graphs are analyzed and discussed whether they can be used in applications to distinguish possible sample

  12. The Statistics of Emission and Detection of Neutrons and Photons from Fissile Samples for Safeguard Applications

    Energy Technology Data Exchange (ETDEWEB)

    Enqvist, Andreas

    2008-03-15

    One particular purpose of nuclear safeguards, in addition to accounting for known materials, is the detection, identifying and quantifying unknown material, to prevent accidental and clandestine transports and uses of nuclear materials. This can be achieved in a non-destructive way through the various physical and statistical properties of particle emission and detection from such materials. This thesis addresses some fundamental aspects of nuclear materials and the way they can be detected and quantified by such methods. Factorial moments or multiplicities have long been used within the safeguard area. These are low order moments of the underlying number distributions of emission and detection. One objective of the present work was to determine the full probability distribution and its dependence on the sample mass and the detection process. Derivation and analysis of the full probability distribution and its dependence on the above factors constitutes the first part of the thesis. Another possibility of identifying unknown samples lies in the information in the 'fingerprints' (pulse shape distribution) left by a detected neutron or photon. A study of the statistical properties of the interaction of the incoming radiation (neutrons and photons) with the detectors constitutes the second part of the thesis. The interaction between fast neutrons and organic scintillation detectors is derived, and compared to Monte Carlo simulations. An experimental approach is also addressed in which cross correlation measurements were made using liquid scintillation detectors. First the dependence of the pulse height distribution on the energy and collision number of an incoming neutron was derived analytically and compared to numerical simulations. Then an algorithm was elaborated which can discriminate neutron pulses from photon pulses. The resulting cross correlation graphs are analyzed and discussed whether they can be used in applications to distinguish possible

  13. Modulation of the pupil function of microscope objective lens for multifocal multi-photon microscopy using a spatial light modulator

    Science.gov (United States)

    Matsumoto, Naoya; Okazaki, Shigetoshi; Takamoto, Hisayoshi; Inoue, Takashi; Terakawa, Susumu

    2014-02-01

    We propose a method for high precision modulation of the pupil function of a microscope objective lens to improve the performance of multifocal multi-photon microscopy (MMM). To modulate the pupil function, we adopt a spatial light modulator (SLM) and place it at the conjugate position of the objective lens. The SLM can generate an arbitrary number of spots to excite the multiple fluorescence spots (MFS) at the desired positions and intensities by applying an appropriate computer-generated hologram (CGH). This flexibility allows us to control the MFS according to the photobleaching level of a fluorescent protein and phototoxicity of a specimen. However, when a large number of excitation spots are generated, the intensity distribution of the MFS is significantly different from the one originally designed due to misalignment of the optical setup and characteristics of the SLM. As a result, the image of a specimen obtained using laser scanning for the MFS has block noise segments because the SLM could not generate a uniform MFS. To improve the intensity distribution of the MFS, we adaptively redesigned the CGH based on the observed MFS. We experimentally demonstrate an improvement in the uniformity of a 10 × 10 MFS grid using a dye solution. The simplicity of the proposed method will allow it to be applied for calibration of MMM before observing living tissue. After the MMM calibration, we performed laser scanning with two-photon excitation to observe a real specimen without detecting block noise segments.

  14. Electrically Induced Two-Photon Transparency in Semiconductor Quantum Wells

    International Nuclear Information System (INIS)

    Hayat, Alex; Nevet, Amir; Orenstein, Meir

    2009-01-01

    We demonstrate experimentally two-photon transparency, achieved by current injection into a semiconductor quantum-well structure which exhibits two-photon emission. The two-photon induced luminescence is progressively reduced by the injected current, reaching the point of two-photon transparency - a necessary condition for semiconductor two-photon gain and lasing. These results agree with our calculations.

  15. Photon propagators at finite temperature

    International Nuclear Information System (INIS)

    Yee, J.H.

    1982-07-01

    We have used the real time formalism to compute the one-loop finite temperature corrections to the photon self energies in spinor and scalar QED. We show that, for a real photon, only the transverse components develop the temperature-dependent masses, while, for an external static electromagnetic field applied to the finite temperature system, only the static electric field is screened by thermal fluctuations. After showing how to compute systematically the imaginary parts of the finite temperature Green functions, we have attempted to give a microscopic interpretation of the imaginary parts of the self energies. (author)

  16. Fano Description of Single-Hydrocarbon Fluorescence Excited by a Scanning Tunneling Microscope.

    Science.gov (United States)

    Kröger, Jörg; Doppagne, Benjamin; Scheurer, Fabrice; Schull, Guillaume

    2018-06-13

    The detection of fluorescence with submolecular resolution enables the exploration of spatially varying photon yields and vibronic properties at the single-molecule level. By placing individual polycyclic aromatic hydrocarbon molecules into the plasmon cavity formed by the tip of a scanning tunneling microscope and a NaCl-covered Ag(111) surface, molecular light emission spectra are obtained that unravel vibrational progression. In addition, light spectra unveil a signature of the molecule even when the tunneling current is injected well separated from the molecular emitter. This signature exhibits a distance-dependent Fano profile that reflects the subtle interplay between inelastic tunneling electrons, the molecular exciton and localized plasmons in at-distance as well as on-molecule fluorescence. The presented findings open the path to luminescence of a different class of molecules than investigated before and contribute to the understanding of single-molecule luminescence at surfaces in a unified picture.

  17. An electrically driven cavity-enhanced source of indistinguishable photons with 61% overall efficiency

    Directory of Open Access Journals (Sweden)

    A. Schlehahn

    2016-04-01

    Full Text Available We report on an electrically driven efficient source of indistinguishable photons operated at pulse-repetition rates f up to 1.2 GHz. The quantum light source is based on a p-i-n-doped micropillar cavity with integrated self-organized quantum dots, which exploits cavity quantum electrodynamics effects in the weak coupling regime to enhance the emission of a single quantum emitter coupled to the cavity mode. We achieve an overall single-photon extraction efficiency of (61 ± 11 % for a device triggered electrically at f = 625 MHz. Analyzing the suppression of multi-photon emission events as a function of excitation repetition rate, we observe single-photon emission associated with g(2HBT(0 values between 0.076 and 0.227 for f ranging from 373 MHz to 1.2 GHz. Hong-Ou-Mandel-type two-photon interference experiments under pulsed current injection at 487 MHz reveal a photon-indistinguishability of (41.1 ± 9.5 % at a single-photon emission rate of (92 ± 23 MHz.

  18. Multiple photon emission in heavy particle decays

    International Nuclear Information System (INIS)

    Asakimori, K.; Burnett, T.H.; Cherry, M.L.

    1994-03-01

    Cosmic ray interactions, at energies above 1 TeV/nucleon, in emulsion chambers flown on high altitude balloons have yielded two events showing apparent decays of a heavy particle into one charged particle and four photons. The photons converted into electron pairs very close to the decay vertex. Attempts to explain this decay topology with known particle decays are presented. Unless both events represent a b → u transition, which is statistically unlikely, then other known decay modes for charmed or bottom particles do not account satisfactorily for these observations. This could indicate, possibly, a new decay channel. (author). 7 refs, 6 figs, 2 tabs

  19. A novel high-efficiency single-mode quantum dot single photon source

    DEFF Research Database (Denmark)

    Gerard, J.M.; Gregersen, Niels; Nielsen, Torben Roland

    2008-01-01

    We present a novel single-mode single photon source exploiting the emission of a semiconductor quantum dot (QD) located inside a photonic wire. Besides an excellent coupling (>95%) of QD spontaneous emission to the fundamental guided mode [1], we show that a single photon collection efficiency...... above 80% within a 0.5 numerical aperture can be achieved using a bottom Bragg mirror and a tapering of the nanowire tip. Because this photon collection strategy does not exploit the Purcell effect, it could also be efficiently applied to broadband single photon emitters such as F-centers in diamond....

  20. 123I-IMP single photon emission computed tomography (SPECT) study in childhood epilepsy

    International Nuclear Information System (INIS)

    Hara, Masafumi; Shimomura, Osamu; Kojima, Akihiro; Izunaga, Hiroshi; Tomiguchi, Seiji; Hirota, Yoshihisa; Taku, Keiichi; Miike, Teruhisa; Takahashi, Mutsumasa

    1990-01-01

    N-isopropyl-p[ 123 I]-iodoamphetamine (IMP) single photon emission computed tomography (SPECT), X-ray computed tomography (X-CT) and magnetic resonance imaging (MRI) were performed in 18 children with idiopathic seizures. In children with idiopathic seizures SPECT identified abnormal lesions in the highest rate (50%) compared with X-CT (11%) and MRI (13%), but the findings of SPECT poorly correlated with the foci on electroencephalography (EEG). Idiopathic epilepsy with abnormal uptake on SPECT was refractory to medical treatments and frequently associated with mental and/or developmental retardation. Perfusion defects identified on SPECT probably influenced the development of the brains in children. IMP SPECT is useful in the diagnosis and medical treatment in children with seizures. (author)

  1. Dynamical Evolution of Properties for Atom and Field in the Process of Two-Photon Absorption and Emission Between Atomic Levels

    Science.gov (United States)

    Wang, Jian-ming; Xu, Xue-xiang

    2018-04-01

    Using dressed state method, we cleverly solve the dynamics of atom-field interaction in the process of two-photon absorption and emission between atomic levels. Here we suppose that the atom is initially in the ground state and the optical field is initially in Fock state, coherent state or thermal state, respectively. The properties of the atom, including the population in excited state and ground state, the atom inversion, and the properties for optical field, including the photon number distribution, the mean photon number, the second-order correlation function and the Wigner function, are discussed in detail. We derive their analytical expressions and then make numerical analysis for them. In contrast with Jaynes-Cummings model, some similar results, such as quantum Rabi oscillation, revival and collapse, are also exhibit in our considered model. Besides, some novel nonclassical states are generated.

  2. Measurement of X-ray emission efficiency for K-lines.

    Science.gov (United States)

    Procop, M

    2004-08-01

    Results for the X-ray emission efficiency (counts per C per sr) of K-lines for selected elements (C, Al, Si, Ti, Cu, Ge) and for the first time also for compounds and alloys (SiC, GaP, AlCu, TiAlC) are presented. An energy dispersive X-ray spectrometer (EDS) of known detection efficiency (counts per photon) has been used to record the spectra at a takeoff angle of 25 degrees determined by the geometry of the secondary electron microscope's specimen chamber. Overall uncertainty in measurement could be reduced to 5 to 10% in dependence on the line intensity and energy. Measured emission efficiencies have been compared with calculated efficiencies based on models applied in standardless analysis. The widespread XPP and PROZA models give somewhat too low emission efficiencies. The best agreement between measured and calculated efficiencies could be achieved by replacing in the modular PROZA96 model the original expression for the ionization cross section by the formula given by Casnati et al. (1982) A discrepancy remains for carbon, probably due to the high overvoltage ratio.

  3. Imaging by single photon emission computed tomography: interest in the pre surgical check up of epilepsy

    International Nuclear Information System (INIS)

    Biraben, A.; Bernard, A.M.

    1999-01-01

    With the single photon emission computed tomography, it is a more reliable technique that is at someone's disposal, especially to limit spatially the evolution of epilepsy crisis before any surgery act. The determination of the precise area is necessary to make sure that the crisis come really from this area and the determination of the functionality of this area is checked to be sure that the ablation of the zone will not lead to an unacceptable functional deficit. (N.C.)

  4. Photon emissivity in the vicinity of a critical point – A case study within the quark meson model

    Energy Technology Data Exchange (ETDEWEB)

    Wunderlich, F., E-mail: f.wunderlich@hzdr.de [Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiation Physics, Bautzner Landstr. 400, D-01328 Dresden (Germany); Institut für Theoretische Physik, Technische Universität Dresden, D-01062 Dresden (Germany); Kämpfer, B., E-mail: kaempfer@hzdr.de [Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiation Physics, Bautzner Landstr. 400, D-01328 Dresden (Germany); Institut für Theoretische Physik, Technische Universität Dresden, D-01062 Dresden (Germany)

    2017-03-15

    The quark meson (linear sigma) model with linearized fluctuations displays at a critical end point the onset of a curve of first-order phase transitions (FOPTs) located at non-zero chemical potentials and temperatures below a certain cross-over temperature. The model qualifies well for an illustrative example to study the impact of the emerging FOPT, e.g. on photon emissivities. Such a case study unravels the tight interlocking of the phase structure with the emission rates, here calculated according to lowest-order tree level processes by kinetic theory expressions. It is the strong dependence of the rates on the effective masses of the involved degrees of freedom which distinctively vary over the phase diagram thus shaping the emissivity accordingly. At the same time, thermodynamic properties of the medium are linked decisively to these effective masses, i.e. a consistent evaluation of thermodynamics, governing for instance adiabatic expansion paths, and emission rates is maintained within such an approach.

  5. Brain hypoperfusion on Tc-99m-ethylene dicysteine diethyl ester single-photon emission computed tomography in Hashimoto's encephalopathy

    OpenAIRE

    Grande, Mar?a Luz Dom?nguez; Constantino, Ana; Rayo, Juan Ignacio; Serrano, Justo; Infante, Jose Rafael; Garcia, Lucia; Duran, Carmen

    2013-01-01

    We present a 17-year-old female, previously diagnosed of autoimmune hyperthyroidism who had an acute neurological episode and presented high antithyroid antibodies titers, cerebral spinal fluid and electroencephalogram changes. Tc-99m ethylene dicysteine diethyl ester brain single-photon emission computed tomography (SPECT) showed global and patchy hypoperfusion. With glucocorticoid therapy, clinical symptoms disappeared; there was a decrease in antithyroid antibody levels and repeat brain SP...

  6. Efficient generation of single and entangled photons on a silicon photonic integrated chip

    International Nuclear Information System (INIS)

    Mower, Jacob; Englund, Dirk

    2011-01-01

    We present a protocol for generating on-demand, indistinguishable single photons on a silicon photonic integrated chip. The source is a time-multiplexed spontaneous parametric down-conversion element that allows optimization of single-photon versus multiphoton emission while realizing high output rate and indistinguishability. We minimize both the scaling of active elements and the scaling of active element loss with multiplexing. We then discuss detection strategies and data processing to further optimize the procedure. We simulate an improvement in single-photon-generation efficiency over previous time-multiplexing protocols, assuming existing fabrication capabilities. We then apply this system to generate heralded Bell states. The generation efficiency of both nonclassical states could be increased substantially with improved fabrication procedures.

  7. Microscopic theory of indistinguishable single-photon emission from a quantum dot coupled to a cavity: The role of non-Markovian phonon-induced decoherence

    DEFF Research Database (Denmark)

    Nielsen, Per Kær; Lodahl, Peter; Jauho, Antti-Pekka

    2013-01-01

    We study the fundamental limit on single-photon indistinguishability imposed by decoherence due to phonon interactions in semiconductor quantum dot-cavity quantum electrodynamics systems. Employing an exact diagonalization approach we find large differences compared to standard methods...

  8. Hot water epilepsy: Phenotype and single photon emission computed tomography observations

    Directory of Open Access Journals (Sweden)

    Mehul Patel

    2014-01-01

    Full Text Available We studied the anatomical correlates of reflex hot water epilepsy (HWE using multimodality investigations viz. magnetic resonance imaging (MRI, electroencephalography (EEG, and single photon emission computed tomography (SPECT. Five men (mean age: 27.0 ΁ 5.8 years with HWE were subjected to MRI of brain, video-EEG studies, and SPECT scan. These were correlated with phenotypic presentations. Seizures could be precipitated in three patients with pouring of hot water over the head and semiology of seizures was suggestive of temporal lobe epilepsy. Ictal SPECT showed hyperperfusion in: left medial temporal - one, left lateral temporal - one, and right parietal - one. Interictal SPECT was normal in all five patients and did not help in localization. MRI and interictal EEG was normal in all the patients. The clinical and SPECT studies suggested temporal lobe as the seizure onset zone in some of the patients with HWE.

  9. Simulation of Far-Field Superresolution Fluorescence Imaging with Two-Color One-Photon Excitation of Reversible Photoactivatable Protein

    International Nuclear Information System (INIS)

    Wang Chen; Qiao Ling-Ling; Mao Zheng-Le

    2011-01-01

    We propose to achieve far-field super-resolution imaging by using offset two-color one-photon (2C1P) excitation of reversible photoactivatable fluorescence proteins. Due to the distinctive photoswitching performance of the proteins, such as dronpa, the fluorescence emission will only come from the overlapped region of activation beam and excitation beam. The analysis solution of rate equation shows that the resolution of offset 2C1P microscope is 'engineered' by laser power of excitation and activation beams and the power ratio between them. Superior lateral and transverse resolution is theoretically demonstrated compared with conventional fluorescence scanning microscopy. (fundamental areas of phenomenology(including applications))

  10. Simultaneous control of emission localization and two-photon absorption efficiency in dissymmetrical chromophores

    International Nuclear Information System (INIS)

    Tretiak, Sergei

    2009-01-01

    The aim of the present work is to demonstrate that combined spectral tuning of fluorescence and two-photon absorption (TPA) properties of multipolar chromophores can be achieved by introduction of slight electronic chemical dissymmetry. In that perspective, two novel series of structurally related chromophores have been designed and studied: a first series based on rod-like quadrupolar chromophores bearing different electron-donating (D) end groups and a second series based on three-branched octupolar chromophores built from a trigonal donating moiety and bearing various acceptor (A) peripheral groups. The influence of the electronic dissymmetry is investigated by combined experimental and theoretical studies of the linear and nonlinear optical properties of dissymmetric chromophores compared to their symmetrical counterparts. In both types of systems (i.e. quadrupoles and octupoles) experiments and theory reveal that excitation is essentially delocalized and that excitation involves synchronized charge redistribution between the different D and A moieties within the multipolar structure (i.e. concerted intramolecular charge transfer). In contrast, the emission stems only from a particular dipolar subunit bearing the strongest D or A moieties due to fast excitation localization after excitation prior to emission. Hence control of emission characteristics (polarization and emission spectrum) in addition to localization can be achieved by controlled introduction of electronic dissymmetry (i.e. replacement of one of the D or A end-groups by a slightly stronger D(prime) or A(prime) units). Interestingly dissymmetrical functionalization of both quadrupolar and octupolar compounds does not lead to significant loss in TPA responses and can even be beneficial due to the spectral broadening and peak position tuning that it allows. This study thus reveals an original molecular engineering route strategy allowing major TPA enhancement in multipolar structures due to concerted

  11. Fast-ICCD photography and gated photon counting measurements of blackbody emission from particulates generated in the KrF-laser ablation of BN and YBCO

    Energy Technology Data Exchange (ETDEWEB)

    Geohegan, D.B.

    1992-11-01

    Fast intensified CCD photography and gated photon counting following KrF-laser irradiation of YBCO and BN targets reveals the first observations of very weak emission from slow-moving ejecta up to 2 cm from the target and times extending to {approx}1.5 ms. Time-of-flight velocities inferred from the emission measurements indicate velocities (v {approximately} (0.45--1.2) {times} 10{sup 4} cm s{sup {minus}1}) comparable to those measured for the large particles which often accompany the pulsed laser deposition process. Gated photon counting is employed to obtain temporally resolved spectra of this weak emission. The spectral shape is characteristic of blackbody emission, which shifts to longer wavelengths as the particles cool during flight in vacuum. Estimates of the temperature of the particles are made based on the emissivity of a perfect blackbody and range from 2200 K to 3200 K for both BN and YBCO when irradiated at ({Phi}{sub 248} = 3.5 J cm{sup {minus}2} and 1.5 J cm{sup {minus}2}, respectively. The temperature decrease of the particles in vacuum is compared to a radiative cooling model which gives estimates of the initial surface temperature and radii of the particles.

  12. Development of a simple photon emission computed tomography dedicated to the small animal

    International Nuclear Information System (INIS)

    Bekaert, V.

    2006-11-01

    The development of in vivo small animal imaging becomes essential to study human pathologies. The ImaBio project of Institut Pluridisciplinaire Hubert Curien (IPHC) fits in the process of developing new instruments for biomedical applications with the development of a multimodality imaging platform dedicated to small animal imaging (AMISSA). This thesis presents the study, the design and the development of a Single Photon Emission Computed Tomography (SPECT) which will be integrated to the AMISSA platform. The result of these developments is the possibility to obtain the spatial distribution of an injected molecule into the animal. The SPECT technical solutions are based on the acquired knowledge of the institute allowing the conception of a device with cameras adapted to the gamma detection produced by the radiotracers used in single photon imaging. In order to cover the entire of the transverse field of view, four gamma cameras are arranged in a ring around the volume of interest. Each camera consists of 5 individual modules based on a YAP:Ce crystal array, a multi-anode photomultiplier and a dedicated multichannel electronic device. Finally, 20 detection modules were calibrated to give the same result for an identical energy deposit. The data are acquired then process to extract the positions and the energies deposited by gamma photons in the crystals. This last information is then gathered to build the projections. The 3D reconstructed image from the projections is carried out by the sequence of two algorithms, analytical and iterative OS-EM, both modified to take into account the singular geometry of our detection system. Finally, the obtained image is fused with the anatomical information given by the micro Computed Tomography system. (author)

  13. Effects of system geometry and other physical factors on photon sensitivity of high-resolution positron emission tomography

    Science.gov (United States)

    Habte, F.; Foudray, A. M. K.; Olcott, P. D.; Levin, C. S.

    2007-07-01

    We are studying two new detector technologies that directly measure the three-dimensional coordinates of 511 keV photon interactions for high-resolution positron emission tomography (PET) systems designed for small animal and breast imaging. These detectors are based on (1) lutetium oxyorthosilicate (LSO) scintillation crystal arrays coupled to position-sensitive avalanche photodiodes (PSAPD) and (2) cadmium zinc telluride (CZT). The detectors have excellent measured 511 keV photon energy resolutions (oriented 'edge-on' with respect to incoming 511 keV annihilation photons and arranged to form a compact FOV with detectors very close to, or in contact with, the subject tissues. In this paper, we used Monte Carlo simulation to study various factors that limit the photon sensitivity of a high-resolution PET system dedicated to small animal imaging. To optimize the photon sensitivity, we studied several possible system geometries for a fixed 8 cm transaxial and 8 cm axial FOV. We found that using rectangular-shaped detectors arranged into a cylindrical geometry does not yield the best photon sensitivity. This is due to the fact that forming rectangular-shaped detectors into a ring produces significant wedge-shaped inter-module gaps, through which Compton-scattered photons in the detector can escape. This effect limits the center point source photon sensitivity to 8% photon sensitivity for the LSO-PSAPD box configuration and >15% for CZT box geometry, using a 350-650 keV energy window setting. These simulation results compare well with analytical estimations. The trend is different for a clinical whole-body PET system that uses conventional LSO-PMT block detectors with larger crystal elements. Simulations predict roughly the same sensitivity for both box and cylindrical detector configurations. This results from the fact that a large system diameter (>80 cm) results in relatively small inter-module gaps in clinical whole-body PET. In addition, the relatively large block

  14. Virtual-pion and two-photon production in pp scattering

    International Nuclear Information System (INIS)

    Scholten, O.; Korchin, A.Yu.

    2002-01-01

    Two-photon production in pp scattering is proposed as a means of studying virtual-pion emission. Such a process is complementary to real-pion emission in pp scattering. The virtual-pion signal is embedded in a background of double-photon bremsstrahlung. We have developed a model to describe this background process and show that in certain parts of phase space the virtual-pion signal gives significant contributions. In addition, through interference with the two-photon bremsstrahlung background, one can determine the relative phase of the virtual-pion process

  15. Refined tip preparation by electrochemical etching and ultrahigh vacuum treatment to obtain atomically sharp tips for scanning tunneling microscope and atomic force microscope

    International Nuclear Information System (INIS)

    Hagedorn, Till; Ouali, Mehdi El; Paul, William; Oliver, David; Miyahara, Yoichi; Gruetter, Peter

    2011-01-01

    A modification of the common electrochemical etching setup is presented. The described method reproducibly yields sharp tungsten tips for usage in the scanning tunneling microscope and tuning fork atomic force microscope. In situ treatment under ultrahigh vacuum (p ≤10 -10 mbar) conditions for cleaning and fine sharpening with minimal blunting is described. The structure of the microscopic apex of these tips is atomically resolved with field ion microscopy and cross checked with field emission.

  16. A single photon emission computed tomograph based on a limited dumber of detectors for fluid flow visualization

    International Nuclear Information System (INIS)

    Legoupil, S.

    1999-01-01

    We present in this work a method for fluid flow visualization in a system using radioactive tracers. The method is based on single photon emission computed tomography techniques, applied to a limited number of discrete detectors. We propose in this work a method for the estimation of the transport matrix of photons, associated to the acquisition system. This method is based on the modelization of profiles acquired for a set of point sources located in the imaged volume. Monte Carlo simulations allow to separate scattered photons from those directly collected by the system. The influence of the energy tracer is exposed. The reconstruction method is based on the maximum likelihood - expectation maximization algorithm. An experimental device, based on 36 detectors was realised for the visualization of water circulation in a vessel. A video monitoring allows to visualize the dye water tracer. Dye and radioactive tracers are injected simultaneously in a water flow circulating in the vessel. Reconstructed and video images are compared. Quantitative and qualitative analysis show that fluid flow visualization is feasible with a limited number of detectors. This method can be applied for system involving circulations of fluids. (author)

  17. A compact two photon light sheet microscope for applications in neuroscience

    DEFF Research Database (Denmark)

    Piksarv, Peeter; Marti, Dominik; Le, Tuan

    2016-01-01

    We present a compact setup for two photon light sheet microscopy. By using pulsed Airy beam illumination we demonstrate eight-fold increase of the FOV compared to Gaussian light sheet with the same axial resolution....

  18. Benzodiazepine receptor equilibrium constants for flumazenil and midazolam determined in humans with the single photon emission computer tomography tracer [123I]iomazenil

    DEFF Research Database (Denmark)

    Videbaek, C; Friberg, L; Holm, S

    1993-01-01

    twice, once without receptor blockade and once with a constant degree of partial blockade of the benzodiazepine receptors by infusion of nonradioactive flumazenil (Lanexat) or midazolam (Dormicum). Single photon emission computer tomography and blood sampling were performed intermittently for 6 h after...

  19. Single photon emission tomography using sup(99m)Tc-HM-PAO in the investigation of dementia

    Energy Technology Data Exchange (ETDEWEB)

    Neary, D; Snowden, J S; Shields, R A; Burjan, A W.I.; Northen, B; Macdermott, N; Prescott, M C; Testa, H J

    1987-09-01

    Single photon emission tomographic imaging of the brain using sup(99m)Tc HM-PAO was carried out in patients with a clinical diagnosis of Alzheimer's disease, non-Alzheimer frontal-lobe dementia, and progressive supranuclear palsy. Independent assessment of reductions in uptake revealed posterior hemisphere abnormalities in the majority of the Alzheimer group, and selective anterior hemisphere abnormalities in both other groups. The findings were consistent with observed patterns of mental impairment. The imaging technique has potential value in the differential diagnosis of primary cerebral atrophy.

  20. Viscous photons in relativistic heavy ion collisions

    International Nuclear Information System (INIS)

    Dion, Maxime; Paquet, Jean-Francois; Young, Clint; Jeon, Sangyong; Gale, Charles; Schenke, Bjoern

    2011-01-01

    Theoretical studies of the production of real thermal photons in relativistic heavy ion collisions at the Relativistic Heavy Ion Collider (RHIC) are performed. The space-time evolution of the colliding system is modelled using music, a 3+1D relativistic hydrodynamic simulation, using both its ideal and viscous versions. The inclusive spectrum and its azimuthal angular anisotropy are studied separately, and the relative contributions of the different photon sources are highlighted. It is shown that the photon v 2 coefficient is especially sensitive to the details of the microscopic dynamics like the equation of state, the ratio of shear viscosity over entropy density, η/s, and to the morphology of the initial state.

  1. Soft photon production in the boost-invariant color-flux tube model

    International Nuclear Information System (INIS)

    Czyz, W.; Florkowski, W.

    1993-07-01

    Starting from the classical expressions for emission of radiation we calculate soft photon production in the boost-invariant color-flux tube model. In the center-of-mass system of the initial tube we find that for large energies (√s ∼ 20 GeV) the production of photons with frequencies: 20 MeV < ω < 50 MeV, and emitted perpendicularly to the collision axis is strongly enhanced; it exceeds considerably production of photons given by the Low limit. For the emission more collinear with the collision axis and for decreasing ω the effect becomes weaker and, eventually, in the limit ω = 0 we recover precisely the Low formula. We also find that for smaller energies (√s ∼ 5 GeV) the emission of photons is well reproduced by the Low formula. Generally speaking, the observed enhancement is related to the existence of a large, i.e. extended in time, region of photon emission. This, in turn, results from the time dilution accompanying the space-time evolution of tubes. Strong time dilution effects follow from the boost-invariance of our model and, for large s, considerably enhance radiation of soft photons. By the same token, this enhancement decreases with decreasing s, because dilation decreases. (author). 21 refs, 7 figs

  2. Soft photon production in the boost-invariant color-flux tube model

    Energy Technology Data Exchange (ETDEWEB)

    Czyz, W. [Uniwersytet Jagiellonski, Cracow (Poland). Inst. Fizyki]|[Institute of Nuclear Physics, Cracow (Poland); Florkowski, W. [Institute of Nuclear Physics, Cracow (Poland)

    1993-07-01

    Starting from the classical expressions for emission of radiation we calculate soft photon production in the boost-invariant color-flux tube model. In the center-of-mass system of the initial tube we find that for large energies ({radical}s {approx} 20 GeV) the production of photons with frequencies: 20 MeV < {omega} < 50 MeV, and emitted perpendicularly to the collision axis is strongly enhanced; it exceeds considerably production of photons given by the Low limit. For the emission more collinear with the collision axis and for decreasing {omega} the effect becomes weaker and, eventually, in the limit {omega} = 0 we recover precisely the Low formula. We also find that for smaller energies ({radical}s {approx} 5 GeV) the emission of photons is well reproduced by the Low formula. Generally speaking, the observed enhancement is related to the existence of a large, i.e. extended in time, region of photon emission. This, in turn, results from the time dilution accompanying the space-time evolution of tubes. Strong time dilution effects follow from the boost-invariance of our model and, for large s, considerably enhance radiation of soft photons. By the same token, this enhancement decreases with decreasing s, because dilation decreases. (author). 21 refs, 7 figs.

  3. Cone beam tomography of the heart using single-photon emission-computed tomography

    International Nuclear Information System (INIS)

    Gullberg, G.T.; Christian, P.E.; Zeng, G.L.; Datz, F.L.; Morgan, H.T.

    1991-01-01

    The authors evaluated cone beam single-photon emission-computed tomography (SPECT) of the heart. A new cone beam reconstruction algorithm was used to reconstruct data collected from short scan acquisitions (of slightly more than 180 degrees) of a detector anteriorally traversing a noncircular orbit. The less than 360 degrees acquisition was used to minimize the attenuation artifacts that result from reconstructing posterior projections of 201T1 emissions from the heart. The algorithm includes a new method for reconstructing truncated projections of background tissue activity that eliminates reconstruction ring artifacts. Phantom and patient results are presented which compare a high-resolution cone beam collimator (50-cm focal length; 6.0-mm full width at half maximum [FWHM] at 10 cm) to a low-energy general purpose (LEGP) parallel hole collimator (8.2-mm FWHM at 10 cm) which is 1.33 times more sensitive. The cone beam tomographic results are free of reconstruction artifacts and show improved spatial and contrast resolution over that obtained with the LEGP parallel hole collimator. The limited angular sampling restrictions and truncation problems associated with cone beam tomography do not deter from obtaining diagnostic information. However, even though these preliminary results are encouraging, a thorough clinical study is still needed to investigate the specificity and sensitivity of cone beam tomography

  4. Super-resolution imaging of ciliary microdomains in isolated olfactory sensory neurons using a custom two-color stimulated emission depletion microscope

    Science.gov (United States)

    Meyer, Stephanie A.; Ozbay, Baris N.; Potcoava, Mariana; Salcedo, Ernesto; Restrepo, Diego; Gibson, Emily A.

    2016-06-01

    We performed stimulated emission depletion (STED) imaging of isolated olfactory sensory neurons (OSNs) using a custom-built microscope. The STED microscope uses a single pulsed laser to excite two separate fluorophores, Atto 590 and Atto 647N. A gated timing circuit combined with temporal interleaving of the different color excitation/STED laser pulses filters the two channel detection and greatly minimizes crosstalk. We quantified the instrument resolution to be ˜81 and ˜44 nm, for the Atto 590 and Atto 647N channels. The spatial separation between the two channels was measured to be under 10 nm, well below the resolution limit. The custom-STED microscope is incorporated onto a commercial research microscope allowing brightfield, differential interference contrast, and epifluorescence imaging on the same field of view. We performed immunolabeling of OSNs in mice to image localization of ciliary membrane proteins involved in olfactory transduction. We imaged Ca2+-permeable cyclic nucleotide gated (CNG) channel (Atto 594) and adenylyl cyclase type III (ACIII) (Atto 647N) in distinct cilia. STED imaging resolved well-separated subdiffraction limited clusters for each protein. We quantified the size of each cluster to have a mean value of 88±48 nm and 124±43 nm, for CNG and ACIII, respectively. STED imaging showed separated clusters that were not resolvable in confocal images.

  5. Aphasia following left thalamic hemorrhage. A study by Western Aphasia Battery and single photon emission CT

    Energy Technology Data Exchange (ETDEWEB)

    Makishita, Hideo; Miyasaka, Motomaro; Tanizaki, Yoshio; Yanagisawa, Nobuo; Sugishita, Morihiro

    1984-07-01

    A report is given of 7 patients with left thalamic hemorrhage in the chronic stage (from 1.5 months to 4.5 months) in which language disorders were examined by Western Aphasia Battery (WAB) and cerebral blood flow was measured by single photon emission CT. Examination of language by WAB revealed 4 aphasics out of 7 cases, and 3 patients had no language deficit. The patient with Wernicke's aphasia showed low density area only in the left posterior thalamus in X-ray CT, and revealed severe low blood flow area extending to left temporal lobe in emission CT. In the case with transcortical sensory aphasia, although X-ray CT showed no obvious low density area, emission CT revealed moderate low flow area in the left temporooccipital region and low blood flow at the left thalamus. In one of the two patients classified as anomic aphasia, emission CT showed slight low flow area at the temporo-occipital region similar to the case with transcortical sensory aphasia. In another case with anomic aphasia there was a wide low density area all over the left thalamus and midline shift to the right in X-ray CT, and emission CT showed severe low blood flow in the same region spreading widely toward the cerebral surface. In all of the 3 patients without aphasia, emission CT showed low flow region restricted to the left thalamus.

  6. High-efficiency single-photon source: The photonic wire geometry

    DEFF Research Database (Denmark)

    Claudon, J.; Bazin, Maela; Malik, Nitin S.

    2009-01-01

    We present a single-photon-source design based on the emission of a quantum dot embedded in a semiconductor (GaAs) nanowire. The nanowire ends are engineered (efficient metallic mirror and tip taper) to reach a predicted record-high collection efficiency of 90% with a realistic design. Preliminar...

  7. Modification and control of the spontaneous emission from an M-type atom embedded in an anisotropic photonic crystal

    International Nuclear Information System (INIS)

    Ding Chunling; Li Jiahua; Yang Xiaoxue; Lue Xinyou

    2011-01-01

    We describe the spontaneous emission properties of an M-type five-level atom embedded in a photonic crystal (PC), which is coherently driven by two external laser fields. It leads to two types of quantum interference: reservoir-induced interference and laser-induced interference. Considering different detunings of atomic transition frequencies from band edges, we reveal some interesting phenomena such as spectral-line enhancement, spectral-line suppression, spectral-line narrowing, reservoir-induced cancellation of spontaneous emission and the appearance of dark lines, which originate from the quantum interference effects and the control of external laser fields. These investigations suggest possible applications in quantum optics, optical communications and in the fabrication of novel optoelectronic devices.

  8. Coherent anti-Stokes Raman scattering microscopy with a photonic crystal fiber based light source

    DEFF Research Database (Denmark)

    Paulsen, H.N.; Hilligsøe, Karen Marie; Thøgersen, J.

    2003-01-01

    A coherent anti-Stokes Raman scattering microscope based on a Ti:sapphire femtosecond oscillator and a photonic crystal fiber is demonstrated. The nonlinear response of the fiber is used to generate the additional wavelength needed in the Raman process. The applicability of the setup is demonstra......A coherent anti-Stokes Raman scattering microscope based on a Ti:sapphire femtosecond oscillator and a photonic crystal fiber is demonstrated. The nonlinear response of the fiber is used to generate the additional wavelength needed in the Raman process. The applicability of the setup...

  9. The development of a high speed 3D 2-photon microscope for neuroscience

    OpenAIRE

    Kirkby, P. A.

    2010-01-01

    The progress of neuroscience is limited by the instrumentation available to it for studying the brain. At present, there is a serious instrumentation gap between functional Magnetic Resonance Imaging (fMRI) of whole brains and the microscopic scale functional imaging possible with today’s optical microscopes and electrophysiology techniques, such as patch clamping of individual neurons. This thesis describes the development of a new extension to optical microscopy that enabl...

  10. Semiconductor quantum optics with tailored photonic nanostructures

    International Nuclear Information System (INIS)

    Laucht, Arne

    2011-01-01

    This thesis describes detailed investigations of the effects of photonic nanostructures on the light emission properties of self-assembled InGaAs quantum dots. Nanoscale optical cavities and waveguides are employed to enhance the interaction between light and matter, i.e. photons and excitons, up to the point where optical non-linearities appear at the quantum (single photon) level. Such non-linearities are an essential component for the realization of hardware for photon based quantum computing since they can be used for the creation and detection of non-classical states of light and may open the way to new genres of quantum optoelectronic devices such as optical modulators and optical transistors. For single semiconductor quantum dots in photonic crystal nanocavities we investigate the coupling between excitonic transitions and the highly localized mode of the optical cavity. We explore the non-resonant coupling mechanisms which allow excitons to couple to the cavity mode, even when they are not spectrally in resonance. This effect is not observed for atomic cavity quantum electrodynamics experiments and its origin is traced to phonon-assisted scattering for small detunings (ΔE ∝5 meV). For quantum dots in high-Q cavities we observe the coherent coupling between exciton and cavity mode in the strong coupling regime of light-matter interaction, probe the influence of pure dephasing on the coherent interaction at high excitation levels and high lattice temperatures, and examine the coupling of two spatially separated quantum dots via the exchange of real and virtual photons mediated by the cavity mode. Furthermore, we study the spontaneous emission properties of quantum dots in photonic crystal waveguide structures, estimate the fraction of all photons emitted into the propagating waveguide mode, and demonstrate the on-chip generation of single photon emission into the waveguide. The results obtained during the course of this thesis contribute significantly to

  11. Frequency Control of Single Quantum Emitters in Integrated Photonic Circuits.

    Science.gov (United States)

    Schmidgall, Emma R; Chakravarthi, Srivatsa; Gould, Michael; Christen, Ian R; Hestroffer, Karine; Hatami, Fariba; Fu, Kai-Mei C

    2018-02-14

    Generating entangled graph states of qubits requires high entanglement rates with efficient detection of multiple indistinguishable photons from separate qubits. Integrating defect-based qubits into photonic devices results in an enhanced photon collection efficiency, however, typically at the cost of a reduced defect emission energy homogeneity. Here, we demonstrate that the reduction in defect homogeneity in an integrated device can be partially offset by electric field tuning. Using photonic device-coupled implanted nitrogen vacancy (NV) centers in a GaP-on-diamond platform, we demonstrate large field-dependent tuning ranges and partial stabilization of defect emission energies. These results address some of the challenges of chip-scale entanglement generation.

  12. Frequency Control of Single Quantum Emitters in Integrated Photonic Circuits

    Science.gov (United States)

    Schmidgall, Emma R.; Chakravarthi, Srivatsa; Gould, Michael; Christen, Ian R.; Hestroffer, Karine; Hatami, Fariba; Fu, Kai-Mei C.

    2018-02-01

    Generating entangled graph states of qubits requires high entanglement rates, with efficient detection of multiple indistinguishable photons from separate qubits. Integrating defect-based qubits into photonic devices results in an enhanced photon collection efficiency, however, typically at the cost of a reduced defect emission energy homogeneity. Here, we demonstrate that the reduction in defect homogeneity in an integrated device can be partially offset by electric field tuning. Using photonic device-coupled implanted nitrogen vacancy (NV) centers in a GaP-on-diamond platform, we demonstrate large field-dependent tuning ranges and partial stabilization of defect emission energies. These results address some of the challenges of chip-scale entanglement generation.

  13. Pinhole single-photon emission tomography reconstruction based on median root prior

    International Nuclear Information System (INIS)

    Sohlberg, Antti; Kuikka, Jyrki T.; Ruotsalainen, Ulla

    2003-01-01

    The maximum likelihood expectation maximisation (ML-EM) algorithm can be used to reduce reconstruction artefacts produced by filtered backprojection (FBP) methods in pinhole single-photon emission tomography (SPET). However, ML-EM suffers from noise propagation along iterations, which leads to quantitatively unpleasant reconstruction results. To avoid this increase in noise, the median root prior (MRP) algorithm for pinhole SPET was implemented. Projection data of a line source and Picker's thyroid phantom were collected using a single-head gamma camera with a pinhole collimator. MRP was added to existing pinhole ML-EM reconstruction algorithm and the phantom studies were reconstructed using MRP, ML-EM and FBP for comparison. Coefficients of variation, contrasts and full-widths at half-maximum were calculated and showed a clear reduction in noise without significant loss of resolution or decrease in contrast when MRP was applied. MRP also produced visually pleasing images even with high iteration numbers, free of the checkerboard-type noise patterns which are typical of ML-EM images. (orig.)

  14. Single photon emission computed tomography (SPECT) in seizure disorders in childhood

    International Nuclear Information System (INIS)

    Vles, J.S.H.; Demandt, E.; Ceulemans, B.; de Roo, M.; Casaer, P.J.M.

    1990-01-01

    In 38 children with partial seizures, the EEG, CT and NMR findings were compared to the results obtained with Tc99m HMPAO single photon emission computed tomography (SPECT) in order to determine whether SPECT is a useful adjunct to EEG, CT and NMR in this age group. In 3 out of 7 patients with a normal EEG, SPECT showed focal abnormalities. Nine patients whose EEGs did not show adequate lateralization had an abnormal SPECT which revealed a focus. In 14 out of 21 patients with a normal CT, SPECT showed focal changes in 13 patients and diffuse changes in the other one. In 7 out of 12 patients with a normal NMR, SPECT showed focal abnormalities. Although clinical history and a careful description of the seizures are the most valuable information in partial seizure disorders, SPECT imaging gives valuable additional information, which might target treatment. SPECT was superior to CT and NMR with respect to the depiction of some kind of abnormality. (author)

  15. Application of transmission scan-based attenuation compensation to scatter-corrected thallium-201 myocardial single-photon emission tomographic images

    International Nuclear Information System (INIS)

    Hashimoto, Jun; Kubo, Atsushi; Ogawa, Koichi; Ichihara, Takashi; Motomura, Nobutoku; Takayama, Takuzo; Iwanaga, Shiro; Mitamura, Hideo; Ogawa, Satoshi

    1998-01-01

    A practical method for scatter and attenuation compensation was employed in thallium-201 myocardial single-photon emission tomography (SPET or ECT) with the triple-energy-window (TEW) technique and an iterative attenuation correction method by using a measured attenuation map. The map was reconstructed from technetium-99m transmission CT (TCT) data. A dual-headed SPET gamma camera system equipped with parallel-hole collimators was used for ECT/TCT data acquisition and a new type of external source named ''sheet line source'' was designed for TCT data acquisition. This sheet line source was composed of a narrow long fluoroplastic tube embedded in a rectangular acrylic board. After injection of 99m Tc solution into the tube by an automatic injector, the board was attached in front of the collimator surface of one of the two detectors. After acquiring emission and transmission data separately or simultaneously, we eliminated scattered photons in the transmission and emission data with the TEW method, and reconstructed both images. Then, the effect of attenuation in the scatter-corrected ECT images was compensated with Chang's iterative method by using measured attenuation maps. Our method was validated by several phantom studies and clinical cardiac studies. The method offered improved homogeneity in distribution of myocardial activity and accurate measurements of myocardial tracer uptake. We conclude that the above correction method is feasible because a new type of 99m Tc external source may not produce truncation in TCT images and is cost-effective and easy to prepare in clinical situations. (orig.)

  16. Replication of polypyrrole with photonic structures from butterfly wings as biosensor

    International Nuclear Information System (INIS)

    Tang Jie; Zhu Shenmin; Chen Zhixin; Feng Chuanliang; Shen Yanjun; Yao Fan; Zhang Di; Moon, Won-Jin; Song, Deok-Min

    2012-01-01

    Highlights: ► Polypyrrole (PPy) with photonic structures from butterfly wings was synthesized based on a two-step templating and in situ polymerization process. ► The hierarchical structures down to nanometer level were kept in the resultant PPy replicas. ► The PPy replicas exhibit brilliant color due to Bragg diffraction through its ordered periodic structures. ► The PPy replicas showed a much higher biological activity compared with common PPy powders as a biosensor. - Abstract: Polypyrrole (PPy) with photonic crystal structures were synthesized from Morpho butterfly wings using a two-step templating process. In the first step photonic crystal SiO 2 butterfly wings were synthesized from Morpho butterfly wings and in the second step the SiO 2 butterfly wings were used as templates for the replication of PPy butterfly wings using an in situ polymerization method. The SiO 2 templates were then removed from the PPy butterfly wings using a HF solution. The hierarchical structures down to the nanometer level, especially the photonic crystal structures, were retained in the final PPy replicas, as evidenced directly by field-emission scanning electron microscope (FE-SEM) and transmission electron microscopy (TEM). The optical properties of the resultant PPy replicas were investigated using reflectance spectroscopy and the PPy replicas exhibit brilliant color due to Bragg diffraction through its ordered periodic structures. The preliminary biosensing application was investigated and it was found that the PPy replicas showed a much higher biological activity compared with PPy powders through their response to dopamine (DA), probably due to the hierarchical structures as well as controlled porosity inherited from Morpho butterfly wings. It is expected that our strategy will open up new avenues for the synthesis of functional polymers with photonic crystal structures, which may form applications as biosensors.

  17. Replication of polypyrrole with photonic structures from butterfly wings as biosensor

    Energy Technology Data Exchange (ETDEWEB)

    Tang Jie [State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240 (China); Zhu Shenmin, E-mail: smzhu@sjtu.edu.cn [State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240 (China); Chen Zhixin [Faculty of Engineering, University of Wollongong, Wollongong, NSW 2522 (Australia); Feng Chuanliang; Shen Yanjun; Yao Fan [State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240 (China); Zhang Di, E-mail: zhangdi@sjtu.edu.cn [State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240 (China); Moon, Won-Jin; Song, Deok-Min [Gwangju Center, Korea Basic Science Institute, Yongbong-dong, Buk-Gu, Gwang ju 500-757 (Korea, Republic of)

    2012-01-05

    Highlights: Black-Right-Pointing-Pointer Polypyrrole (PPy) with photonic structures from butterfly wings was synthesized based on a two-step templating and in situ polymerization process. Black-Right-Pointing-Pointer The hierarchical structures down to nanometer level were kept in the resultant PPy replicas. Black-Right-Pointing-Pointer The PPy replicas exhibit brilliant color due to Bragg diffraction through its ordered periodic structures. Black-Right-Pointing-Pointer The PPy replicas showed a much higher biological activity compared with common PPy powders as a biosensor. - Abstract: Polypyrrole (PPy) with photonic crystal structures were synthesized from Morpho butterfly wings using a two-step templating process. In the first step photonic crystal SiO{sub 2} butterfly wings were synthesized from Morpho butterfly wings and in the second step the SiO{sub 2} butterfly wings were used as templates for the replication of PPy butterfly wings using an in situ polymerization method. The SiO{sub 2} templates were then removed from the PPy butterfly wings using a HF solution. The hierarchical structures down to the nanometer level, especially the photonic crystal structures, were retained in the final PPy replicas, as evidenced directly by field-emission scanning electron microscope (FE-SEM) and transmission electron microscopy (TEM). The optical properties of the resultant PPy replicas were investigated using reflectance spectroscopy and the PPy replicas exhibit brilliant color due to Bragg diffraction through its ordered periodic structures. The preliminary biosensing application was investigated and it was found that the PPy replicas showed a much higher biological activity compared with PPy powders through their response to dopamine (DA), probably due to the hierarchical structures as well as controlled porosity inherited from Morpho butterfly wings. It is expected that our strategy will open up new avenues for the synthesis of functional polymers with photonic

  18. Single photon emission computed tomography study of human pulmonary perfusion: preliminary findings

    Energy Technology Data Exchange (ETDEWEB)

    Carratu, L; Sofia, M [Naples Univ. (Italy). Facolta di Medicina e Chirurgia; Salvatore, M; Muto, P; Ariemma, G [Istituto Nazionale per la Prevenzione, Lo Studio e La Cura dei Tumori Fondazione Pascale, Naples (Italy); Lopez-Majano, V [Cook County Hospital, Chicago, IL (USA). Nuclear Medicine Div.

    1984-02-01

    Single photon emission computed tomography (SPECT) was performed with /sup 99/Tcsup(m)-albumin macroaggregates to study human pulmonary perfusion in healthy subjects and patients with respiratory diseases such as chronic obstructive pulmonary disease (COPD) and lung neoplasms. The reconstructed SPECT data was displayed in coronal, transverse, sagittal plane sections and compared to conventional perfusion scans. The SPECT data gave more complicated anatomical information about the extent of damage and morphology of the pulmonary vascular bed. In healthy subjects and COPD patients, qualitative and quantitative assessment of pulmonary perfusion could be obtained from serial SPECT scans with respect to distribution and relative concentration of the injected radiopharmaceutical. Furthermore, SPECT of pulmonary perfusion has been useful in detecting the extent of damage to the pulmonary circulation. This is useful for the preoperative evaluation and staging of lung cancer.

  19. Single-photon emission tomography (SPECT) with 123I-amphetamine in cerebral ischemia

    International Nuclear Information System (INIS)

    Koenig, B.; Donis, J.; Mostbeck, A.; Koehn, H.

    1987-01-01

    The uptake of 123 I-amphetamine (IMP) in brain mainly corresponds to regional perfusion. Distribution of IMP can be visualized in tomographic slices by single-photon emission computed tomography (SPECT). For better evaluation and comparison in follow-up studies, right/left ratios were computed and an asymmetry index calculated. The most sensitive asymmetry index was achieved by 120 average circumferential profiles. In 52 patients with stroke and 16 controls the respective sensitivities of IMP-SPECT, computed tomography (CT), static and dynamic brain scanning and angiography were evaluated. In patients with TIA and PRIND the IMP-SPECT had the highest sensitivity of all non-invasive methods. In patients with completed stroke, the sensitivity of IMP-SPECT was comparable with that of CT (90 vs. 93%). There was a significant correlation between the IMP asymmetry index and the clinical and social score (p [de

  20. Aberration correction in photoemission microscopy and applications in photonics and plasmonics

    Energy Technology Data Exchange (ETDEWEB)

    Koenenkamp, Rolf [Portland State Univ., Portland, OR (United States)

    2017-09-28

    We report on the design, assembly, operation and application of an aberration-corrected photoemission electron microscope. The instrument used novel hyperbolic mirror-correctors with two and three electrodes that allowed simultaneous correction of spherical and chromatic aberrations. A spatial resolution of 5.4nm was obtained with this instrument in 2009, and 4.7nm in subsequent years. New imaging methodology was introduced involving interferometric imaging of light diffraction. This methodology was applied in nano-photonics and in the characterization of surface-plasmon polaritons. Photonic crystals and waveguides, optical antennas and new plasmonic devices such as routers, localizers and filters were designed and demonstrated using the new capabilities offered by the microscope.

  1. Ultra-large field-of-view two-photon microscopy

    OpenAIRE

    Tsai, Philbert S.; Mateo, Celine; Field, Jeffrey J.; Schaffer, Chris B.; Anderson, Matthew E.; Kleinfeld, David

    2015-01-01

    We present a two-photon microscope that images the full extent of murine cortex with an objective-limited spatial resolution across an 8 mm by 10 mm field. The lateral resolution is approximately 1 µm and the maximum scan speed is 5 mm/ms. The scan pathway employs large diameter compound lenses to minimize aberrations and performs near theoretical limits. We demonstrate the special utility of the microscope by recording resting-state vasomotion across both hemispheres of the murine brain thro...

  2. On the efficiency of photon emission during electrical breakdown in silicon

    International Nuclear Information System (INIS)

    Nepomuk Otte, A.

    2009-01-01

    This paper presents a study of photons that are emitted during electrical breakdown in p-n silicon diodes. The method that was developed for this study uses the optical-crosstalk effect that is observed in Geigermode-APD (G-APD) photon detectors. The outcome of this study is twofold: firstly, mainly photons with energies between 1.15 and 1.4 eV contribute to the optical crosstalk in G-APDs used in this study. This observation is explained by the strong energy dependence of the absorption length of photons in silicon. Secondly, the intensity with which photons with energies between 1.15 and 1.4 eV are emitted during a breakdown is 3x10 -5 photons per charge carrier in the breakdown region. The uncertainty of the intensity is estimated to be a factor of two. For this study a simulation package Siliconphotomultiplier Simulator (SiSi) was developed, which can be used to address various other questions that arise in the application of G-APDs.

  3. Study of the effective inverse photon efficiency using optical emission spectroscopy combined with cavity ring-down spectroscopy approach

    Science.gov (United States)

    Wu, Xingwei; Li, Cong; Wang, Yong; Wang, Zhiwei; Feng, Chunlei; Ding, Hongbin

    2015-09-01

    The hydrocarbon impurities formation is inevitable due to wall erosion in a long pulse high performance scenario with carbon-based plasma facing materials in fusion devices. The standard procedure to determine the chemical erosion yield in situ is by means of inverse photon efficiency D/XB. In this work, the conversion factor between CH4 flux and photon flux of CH A → X transition (effective inverse photon efficiency PE-1) was measured directly using a cascaded arc plasma simulator with argon/methane. This study shows that the measured PE-1 is different from the calculated D/XB. We compared the photon flux measured by optical emission spectroscopy (OES) and calculated by electron impact excitation of CH(X) which was diagnosed by cavity ring-down spectroscopy (CRDS). It seems that charge exchange and dissociative recombination processes are the main channels of CH(A) production and removal which lead to the inconsistency of PE -1 and D/XB at lower temperature. Meanwhile, the fraction of excited CH(A) produced by dissociative recombination processes was investigated, and we found it increased with Te in the range from 4% to 13% at Te definition instead of D/XB since the electron impact excitation is not the only channel of CH(A) production. These results have an effect on evaluating the yield of chemical erosion in divertor of fusion device.

  4. Brain hypoperfusion on Tc-99m-ethylene dicysteine diethyl ester single-photon emission computed tomography in Hashimoto's encephalopathy

    International Nuclear Information System (INIS)

    Grande, María Luz Domínguez; Rayo, Juan Ignacio; Serrano, Justo; Infante, Jose Rafael; Garcia, Lucia; Duran, Carmen; Constantino, Ana

    2013-01-01

    We present a 17-year-old female, previously diagnosed of autoimmune hyperthyroidism who had an acute neurological episode and presented high antithyroid antibodies titers, cerebral spinal fluid and electroencephalogram changes. 99m Tc ethylene dicysteine diethyl ester brain single-photon emission computed tomography (SPECT) showed global and patchy hypoperfusion. With glucocorticoid therapy, clinical symptoms disappeared; there was a decrease in antithyroid antibody levels and repeat brain SPECT revealed improvement of perfusion. (author)

  5. Coherent beam control through inhomogeneous media in multi-photon microscopy

    Science.gov (United States)

    Paudel, Hari Prasad

    Multi-photon fluorescence microscopy has become a primary tool for high-resolution deep tissue imaging because of its sensitivity to ballistic excitation photons in comparison to scattered excitation photons. The imaging depth of multi-photon microscopes in tissue imaging is limited primarily by background fluorescence that is generated by scattered light due to the random fluctuations in refractive index inside the media, and by reduced intensity in the ballistic focal volume due to aberrations within the tissue and at its interface. We built two multi-photon adaptive optics (AO) correction systems, one for combating scattering and aberration problems, and another for compensating interface aberrations. For scattering correction a MEMS segmented deformable mirror (SDM) was inserted at a plane conjugate to the objective back-pupil plane. The SDM can pre-compensate for light scattering by coherent combination of the scattered light to make an apparent focus even at a depths where negligible ballistic light remains (i.e. ballistic limit). This problem was approached by investigating the spatial and temporal focusing characteristics of a broad-band light source through strongly scattering media. A new model was developed for coherent focus enhancement through or inside the strongly media based on the initial speckle contrast. A layer of fluorescent beads under a mouse skull was imaged using an iterative coherent beam control method in the prototype two-photon microscope to demonstrate the technique. We also adapted an AO correction system to an existing in three-photon microscope in a collaborator lab at Cornell University. In the second AO correction approach a continuous deformable mirror (CDM) is placed at a plane conjugate to the plane of an interface aberration. We demonstrated that this "Conjugate AO" technique yields a large field-of-view (FOV) advantage in comparison to Pupil AO. Further, we showed that the extended FOV in conjugate AO is maintained over a

  6. Oblique photon expansion of QED structure functions

    International Nuclear Information System (INIS)

    Chahine, C.

    1986-01-01

    In the oblique photon expansion, the collinear part of photon emission is summed up to all orders in perturbation theory. The number of oblique or non-collinear photons is the expansion order. Unlike in perturbation theory, every term of the expansion is both infrared finite and gauge invariant. The zero oblique photon contribution to the electromagnetic structure tensor in QED is computed in detail. The behaviors of the structure functions F1 and F2 are discussed in the soft and ultra-soft limits

  7. Two-photon emission and multiphoton absorption by atoms

    International Nuclear Information System (INIS)

    Mu, X.

    1988-01-01

    This thesis consists of investigations of two problems concerning photon-atom interactions. The first topic deals with two-photon transitions in atomic inner shells. An independent-particle model has been used to describe the two-photon transitions between different inner-shell electron states. The first relativistic self-consistent-field calculation of these transition rates in Ag, Mo, and Xe has been carried out. The theoretical results are compared with recent measurements. Good agreement with measured rates is found except in some cases where more reliable experiments still need to be done. The second topic is multiphoton multiionization of atoms. The maximum entropy principle has been employed in this theoretical investigation. A detailed statistical analysis of measured ionic charge distributions produced in strong laser pulses has been carried out. The results of this analysis indicates that the charge-state distribution is a Poissonian, rather than the binomial which prevails under infrared radiation, and hence that ionization occurs stepwise during the pulse. This result is shown to be consistent with experimental data

  8. Chemical-state-selective mapping at nanometer scale using synchrotron radiation and photoelectron emission microscopy

    International Nuclear Information System (INIS)

    Hirao, Norie; Baba, Yuji; Sekiguchi, Tetsuhiro; Shimoyama, Iwao; Honda, Mitsunori

    2010-01-01

    For surface analyses of semiconductor devices and various functional materials, it has become indispensable to analyze valence states at nanometer scale due to the rapid developments of nanotechnology. Since a method for microscopic mapping dependent on the chemical bond states has not been established so far, we have developed a photoelectron emission microscopy (PEEM) system combined with synchrotron soft X-ray excitation. The samples investigated were Si/SiO x micro-patterns prepared by O 2 + ion implantation in Si(001) wafer using a mask. PEEM images excited by various photon energies around the Si K-edge were observed. The lateral spatial resolution of the system was about 41 nm. The brightness of each spot in PEEM images changed depending on the photon energy, due to the X-ray absorption intensity of the respective chemical state. Since the surface of this sample was topographically flat, it has been demonstrated that the present method can be applied to observations of the microscopic pattern, depending not on the morphology, but only on the valence states of silicon. We have also in-situ measured the changes of the PEEM images upon annealing, and elucidated the mechanism of the lateral diffusion of oxygen and valence states of silicon at the nanometer scale. (author)

  9. Chemical-state-selective mapping at nanometer scale using synchrotron radiation and photoelectron emission microscopy

    International Nuclear Information System (INIS)

    Hirao, Norie; Baba, Yuji; Sekiguchi, Tetsuhiro; Shimoyama, Iwao; Honda, Mitsunori

    2008-01-01

    For surface analyses of semiconductor devices and various functional materials, it has become indispensable to analyze the valence states at the nanometer scale due to the rapid developments of nanotechnology. Since a method for microscopic mapping dependent on the chemical bond states has not been established so far, we have developed a photoelectron emission microscopy (PEEM) system combined with synchrotron soft X-ray excitation. The samples investigated were Si/SiO x micro-patterns prepared by O 2 + ion implantation in a Si(001) wafer using a mask. PEEM images excited by various photon energies around the Si K-edge were observed. The lateral spatial resolution of the system was about 41 nm. The brightness of each spot in PEEM images changed depending on the photon energy, due to the X-ray absorption intensity of the respective chemical state. Since the surface of this sample is topographically flat, it has been demonstrated that the present method can be applied to observations of the microscopic pattern, depending not on the morphology, but only on the valence states of silicon. We have also in-situ measured the changes of PEEM images upon annealing, and elucidated the mechanism of the lateral diffusion of oxygen and valence states of silicon at the nanometer scale. (author)

  10. Emissions in potassium vapour under 4S1/2-7S1/2 two-photon nsec excitation

    International Nuclear Information System (INIS)

    Pentaris, D.; Chatzikyriakos, G.; Armyras, A.; Efthimiopoulos, T.

    2010-01-01

    The two-photon excitation of 4S 1/2 -7S 1/2 transition of potassium atoms is studied. Several coherent emissions and processes are possible, such as parametric four-wave (PFWM), parametric six-wave (PSWM) mixing and competition with the stimulated hyper Raman (SHRS) and the amplified spontaneous emission (ASE). The radiations at the transitions 6P 3/2,1/2 -4S 1/2 , 6S 1/2 -4P 3/2,1/2 and 5P 3/2,1/2 -4S 1/2 are emitted only in the forward direction (indicating a parametric process), while the radiation at the transition 4P 3/2,1/2 -4S 1/2 is emitted in the forward and in the backward direction, indicating an ASE process.

  11. Refined tip preparation by electrochemical etching and ultrahigh vacuum treatment to obtain atomically sharp tips for scanning tunneling microscope and atomic force microscope.

    Science.gov (United States)

    Hagedorn, Till; El Ouali, Mehdi; Paul, William; Oliver, David; Miyahara, Yoichi; Grütter, Peter

    2011-11-01

    A modification of the common electrochemical etching setup is presented. The described method reproducibly yields sharp tungsten tips for usage in the scanning tunneling microscope and tuning fork atomic force microscope. In situ treatment under ultrahigh vacuum (p ≤10(-10) mbar) conditions for cleaning and fine sharpening with minimal blunting is described. The structure of the microscopic apex of these tips is atomically resolved with field ion microscopy and cross checked with field emission. © 2011 American Institute of Physics

  12. Confocal multispot microscope for fast and deep imaging in semicleared tissues

    Science.gov (United States)

    Adam, Marie-Pierre; Müllenbroich, Marie Caroline; Di Giovanna, Antonino Paolo; Alfieri, Domenico; Silvestri, Ludovico; Sacconi, Leonardo; Pavone, Francesco Saverio

    2018-02-01

    Although perfectly transparent specimens are imaged faster with light-sheet microscopy, less transparent samples are often imaged with two-photon microscopy leveraging its robustness to scattering; however, at the price of increased acquisition times. Clearing methods that are capable of rendering strongly scattering samples such as brain tissue perfectly transparent specimens are often complex, costly, and time intensive, even though for many applications a slightly lower level of tissue transparency is sufficient and easily achieved with simpler and faster methods. Here, we present a microscope type that has been geared toward the imaging of semicleared tissue by combining multispot two-photon excitation with rolling shutter wide-field detection to image deep and fast inside semicleared mouse brain. We present a theoretical and experimental evaluation of the point spread function and contrast as a function of shutter size. Finally, we demonstrate microscope performance in fixed brain slices by imaging dendritic spines up to 400-μm deep.

  13. Development of a backscattering type ultraviolet apertureless near-field scanning optical microscope.

    Science.gov (United States)

    Kwon, Sangjin; Jeong, Hyun; Jeong, Mun Seok; Jeong, Sungho

    2011-08-01

    A backscattering type ultraviolet apertureless near-field scanning optical microscope (ANSOM) for the correlated measurement of topographical and optical characteristics of photonic materials with high optical resolution was developed. The near-field Rayleigh scattering image of GaN covered with periodic submicron Cr dots showed that optical resolution around 40 nm was achievable. By measuring the tip scattered photoluminescence of InGaN/GaN multi quantum wells, the applicability of the developed microscope for high resolution fluorescence measurement was also demonstrated.

  14. Plasmonic nanofocusing of light in an integrated silicon photonics platform.

    Science.gov (United States)

    Desiatov, Boris; Goykhman, Ilya; Levy, Uriel

    2011-07-04

    The capability to focus electromagnetic energy at the nanoscale plays an important role in nanoscinece and nanotechnology. It allows enhancing light matter interactions at the nanoscale with applications related to nonlinear optics, light emission and light detection. It may also be used for enhancing resolution in microscopy, lithography and optical storage systems. Hereby we propose and experimentally demonstrate the nanoscale focusing of surface plasmons by constructing an integrated plasmonic/photonic on chip nanofocusing device in silicon platform. The device was tested directly by measuring the optical intensity along it using a near-field microscope. We found an order of magnitude enhancement of the intensity at the tip's apex. The spot size is estimated to be 50 nm. The demonstrated device may be used as a building block for "lab on a chip" systems and for enhancing light matter interactions at the apex of the tip.

  15. Engineering a light-emitting planar defect within three-dimensional photonic crystals

    Directory of Open Access Journals (Sweden)

    Guiqiang Liu, Yan Chen and Zhiqing Ye

    2009-01-01

    Full Text Available Sandwich structures, constructed from a planar defect of rhodamine-B (RhB-doped titania (TiO2 and two photonic crystals, were synthesized via the self-assembly method combined with spin-coating. The modification of the spontaneous emission of RhB molecules in such structures was investigated experimentally. The spontaneous emission of RhB-doped TiO2 film with photonic crystals was reduced by a factor of 5.5 over a large bandwidth of 13% of the first-order Bragg diffraction frequency when compared with that of RhB-doped TiO2 film without photonic crystals. The angular dependence of the modification and the photoluminescence lifetime of RhB molecules demonstrate that the strong and wide suppression of the spontaneous emission of the RhB molecules is due to the presence of the photonic band gap.

  16. Engineering a light-emitting planar defect within three-dimensional photonic crystals

    Science.gov (United States)

    Liu, Guiqiang; Chen, Yan; Ye, Zhiqing

    2009-01-01

    Sandwich structures, constructed from a planar defect of rhodamine-B (RhB)-doped titania (TiO2) and two photonic crystals, were synthesized via the self-assembly method combined with spin-coating. The modification of the spontaneous emission of RhB molecules in such structures was investigated experimentally. The spontaneous emission of RhB-doped TiO2 film with photonic crystals was reduced by a factor of 5.5 over a large bandwidth of 13% of the first-order Bragg diffraction frequency when compared with that of RhB-doped TiO2 film without photonic crystals. The angular dependence of the modification and the photoluminescence lifetime of RhB molecules demonstrate that the strong and wide suppression of the spontaneous emission of the RhB molecules is due to the presence of the photonic band gap. PMID:27877309

  17. Imaging of surface plasmon polariton interference using phase-sensitive scanning tunneling microscope

    NARCIS (Netherlands)

    Jose, J.; Segerink, Franciscus B.; Korterik, Jeroen P.; Herek, Jennifer Lynn; Offerhaus, Herman L.

    2011-01-01

    We report the surface plasmon polariton interference, generated via a ‘buried’ gold grating, and imaged using a phase-sensitive Photon Scanning Tunneling Microscope (PSTM). The phase-resolved PSTM measurement unravels the complex surface plasmon polariton interference fields at the gold-air

  18. New Possibilities of Positron-Emission Tomography

    Science.gov (United States)

    Volobuev, A. N.

    2018-01-01

    The reasons for the emergence of the angular distribution of photons generated as a result of annihilation of an electron and a positron in a positron-emission tomograph are investigated. It is shown that the angular distribution of the radiation intensity (i.e., the probability of photon emission at different angles) is a consequence of the Doppler effect in the center-of-mass reference system of the electron and the positron. In the reference frame attached to the electron, the angular distribution of the number of emitted photons does not exists but is replaced by the Doppler shift of the frequency of photons. The results obtained in this study make it possible to extend the potentialities of the positron-emission tomograph in the diagnostics of diseases and to obtain additional mechanical characteristics of human tissues, such as density and viscosity.

  19. Tapered fiber coupling of single photons emitted by a deterministically positioned single nitrogen vacancy center

    Energy Technology Data Exchange (ETDEWEB)

    Liebermeister, Lars, E-mail: lars.liebermeister@physik.uni-muenchen.de; Petersen, Fabian; Münchow, Asmus v.; Burchardt, Daniel; Hermelbracht, Juliane; Tashima, Toshiyuki [Fakultät für Physik, Ludwig-Maximilians-Universität München, 80799 München (Germany); Schell, Andreas W.; Benson, Oliver [Institut für Physik, Humboldt-Universität zu Berlin, 12489 Berlin (Germany); Meinhardt, Thomas; Krueger, Anke [Institut für Organische Chemie, Universität Würzburg, 97074 Würzburg (Germany); Wilhelm Conrad Roentgen Research Center for Complex Materials Systems, Universität Würzburg, 97074 Würzburg (Germany); Stiebeiner, Ariane; Rauschenbeutel, Arno [Atominstitut, Technische Universität Wien, 1020 Wien (Austria); Weinfurter, Harald; Weber, Markus, E-mail: markusweber@lmu.de [Fakultät für Physik, Ludwig-Maximilians-Universität München, 80799 München (Germany); Max-Planck-Institut für Quantenoptik, 85748 Garching (Germany)

    2014-01-20

    A diamond nano-crystal hosting a single nitrogen vacancy (NV) center is optically selected with a confocal scanning microscope and positioned deterministically onto the subwavelength-diameter waist of a tapered optical fiber (TOF) with the help of an atomic force microscope. Based on this nano-manipulation technique, we experimentally demonstrate the evanescent coupling of single fluorescence photons emitted by a single NV-center to the guided mode of the TOF. By comparing photon count rates of the fiber-guided and the free-space modes and with the help of numerical finite-difference time domain simulations, we determine a lower and upper bound for the coupling efficiency of (9.5 ± 0.6)% and (10.4 ± 0.7)%, respectively. Our results are a promising starting point for future integration of single photon sources into photonic quantum networks and applications in quantum information science.

  20. Simple method for sub-diffraction resolution imaging of cellular structures on standard confocal microscopes by three-photon absorption of quantum dots.

    Directory of Open Access Journals (Sweden)

    Anje Sporbert

    Full Text Available This study describes a simple technique that improves a recently developed 3D sub-diffraction imaging method based on three-photon absorption of commercially available quantum dots. The method combines imaging of biological samples via tri-exciton generation in quantum dots with deconvolution and spectral multiplexing, resulting in a novel approach for multi-color imaging of even thick biological samples at a 1.4 to 1.9-fold better spatial resolution. This approach is realized on a conventional confocal microscope equipped with standard continuous-wave lasers. We demonstrate the potential of multi-color tri-exciton imaging of quantum dots combined with deconvolution on viral vesicles in lentivirally transduced cells as well as intermediate filaments in three-dimensional clusters of mouse-derived neural stem cells (neurospheres and dense microtubuli arrays in myotubes formed by stacks of differentiated C2C12 myoblasts.

  1. Role of single photon emission computed tomography/computed tomography in diagnostic iodine-131 scintigraphy before initial radioiodine ablation in differentiated thyroid cancer

    International Nuclear Information System (INIS)

    Agrawal, Kanhaiyalal; Bhattacharya, Anish; Mittal, Bhagwant Rai

    2005-01-01

    The study was performed to evaluate the incremental value of single photon emission computed tomography/computed tomography (SPECT/CT) over planar radioiodine imaging before radioiodine ablation in the staging, management and stratification of risk of recurrence (ROR) in differentiated thyroid cancer (DTC) patients. Totally, 83 patients (21 male, 62 female) aged 17–75 (mean 39.9) years with DTC were included consecutively in this prospective study. They underwent postthyroidectomy planar and SPECT/CT scans after oral administration of 37–114 MBq iodine-131 (I-131). The scans were interpreted as positive, negative or suspicious for tracer uptake in the thyroid bed, cervical lymph nodes and sites outside the neck. In each case, the findings on planar images were recorded first, without knowledge of SPECT/CT findings. Operative and pathological findings were used for postsurgical tumor–node–metastasis staging. The tumor staging was reassessed after each of these two scans. Single photon emission computed tomography/computed tomography localized radioiodine uptake in the thyroid bed in 9/83 (10.8%) patients, neck nodes in 24/83 (28.9%) patients and distant metastases in 8/83 (9.6%) patients in addition to the planar study. Staging was changed in 8/83 (9.6%), ROR in 11/83 (13.2%) and management in 26/83 (31.3%) patients by the pretherapy SPECT/CT in comparison to planar imaging. SPECT/CT had incremental value in 32/83 patients (38.5%) over the planar scan. Single photon emission computed tomography/computed tomography is feasible during a diagnostic I-131 scan with a low amount of radiotracer. It improved the interpretation of pretherapy I-131 scintigraphy and changed the staging and subsequent patient management

  2. Single-photon emission computed tomography in human immunodeficiency virus encephalopathy: A preliminary report

    International Nuclear Information System (INIS)

    Masdeu, J.C.; Yudd, A.; Van Heertum, R.L.; Grundman, M.; Hriso, E.; O'Connell, R.A.; Luck, D.; Camli, U.; King, L.N.

    1991-01-01

    Depression or psychosis in a previously asymptomatic individual infected with the human immunodeficiency virus (HIV) may be psychogenic, related to brain involvement by the HIV or both. Although prognosis and treatment differ depending on etiology, computed tomography (CT) and magnetic resonance imaging (MRI) are usually unrevealing in early HIV encephalopathy and therefore cannot differentiate it from psychogenic conditions. Thirty of 32 patients (94%) with HIV encephalopathy had single-photon emission computed tomography (SPECT) findings that differed from the findings in 15 patients with non-HIV psychoses and 6 controls. SPECT showed multifocal cortical and subcortical areas of hypoperfusion. In 4 cases, cognitive improvement after 6-8 weeks of zidovudine (AZT) therapy was reflected in amelioration of SPECT findings. CT remained unchanged. SPECT may be a useful technique for the evaluation of HIV encephalopathy

  3. Multi-photon excitation microscopy for advanced biomedical imaging

    NARCIS (Netherlands)

    Gadella, B.M.; Haeften, T.W. van; Bavel, Kees van; Valentijn, Jack A.

    Fluorescence microscopy (FM) is a technique traditionally used for determining biological structures [33]; its basic concept is summarised in Figure 1a. The biological specimen under examination is labelled with one or more fluorescent probes before being placed in the microscope. A single photon

  4. Sacrococcygeal chordoma: increased 99mTc methylene diphosphonate uptake on single photon emission computed tomography/computed tomography bone scintigraphy

    International Nuclear Information System (INIS)

    Kamaleshwaran, Koramadai Karuppuswamy; Bhattacharya, Anish; Harisankar, Chidambaram Natarajan Balasubramaniam; Mittal, Bhagwant Rai; Goni, Vijay

    2012-01-01

    Chordoma is a malignant tumor arising from the remnants of the notochord, and is the most frequent primitive tumor of the sacrum. While most sacral tumors show increased concentration of bone-seeking radiopharmaceuticals, chordomas usually exhibit decreased uptake. The authors present an image of a sacrococcygeal chordoma with osteolysis and increased uptake of 99m Tc methylene diphosphonate on planar and single photon emission computed tomography/computed tomography bone scintigraphy. (author)

  5. Degenerative dementia: nosological aspects and results of single photon emission computed tomography; Les demences degeneratives: aspects nosologiques et resultats de la tomographie d'emission monophotonique

    Energy Technology Data Exchange (ETDEWEB)

    Dubois, B.; Habert, M.O. [Hopital Pitie-Salpetriere, 75 - Paris (France)

    1999-12-01

    Ten years ago, the diagnosis discussion of a dementia case for the old patient was limited to two pathologies: the Alzheimer illness and the Pick illness. During these last years, the frame of these primary degenerative dementia has fallen into pieces. The different diseases and the results got with single photon emission computed tomography are discussed. for example: fronto-temporal dementia, primary progressive aphasia, progressive apraxia, visio-spatial dysfunction, dementia at Lewy's bodies, or cortico-basal degeneration. (N.C.)

  6. Bio-Photonic Detection of Various Cellular Cultures

    Science.gov (United States)

    Hann, Patrick; Garzon, Maria; Pfeiffer, Erik; Lofland, Samuel; Knoesel, Ernst

    2008-03-01

    Since it is non-invasive, there has been increased research in the field of bio-optics. Many biological systems display an unusual phenomenon, delayed luminescence, produced by what is known as bio-photons. We present an apparatus and procedure for the detection of these ultra-weak photonic emissions using a single photon detection device. The results of bread yeast, saccramyces, and algae will be presented and compared to other reports in the literature

  7. Dosimetric characterization of radionuclides for systemic tumor therapy: Influence of particle range, photon emission, and subcellular distribution

    International Nuclear Information System (INIS)

    Uusijaervi, Helena; Bernhardt, Peter; Ericsson, Thomas; Forssell-Aronsson, Eva

    2006-01-01

    Various radionuclides have been proposed for systemic tumor therapy. However, in most dosimetric analysis of proposed radionuclides the charged particles are taken into consideration while the potential photons are ignored. The photons will cause undesirable irradiation of normal tissue, and increase the probability of toxicity in, e.g., the bone marrow. The aim of this study was to investigate the dosimetric properties according to particle range, photon emission, and subcellular radionuclide distribution, of a selection of radionuclides used or proposed for radionuclide therapy, and to investigate the possibility of dividing radionuclides into groups according to their dosimetric properties. The absorbed dose rate to the tumors divided by the absorbed dose rate to the normal tissue (TND) was estimated for different tumor sizes in a mathematical model of the human body. The body was simulated as a 70-kg ellipsoid and the tumors as spheres of different sizes (1 ng-100 g). The radionuclides were either assumed to be uniformly distributed throughout the entire tumor and normal tissue, or located in the nucleus or the cytoplasm of the tumor cells and on the cell membrane of the normal cells. Fifty-nine radionuclides were studied together with monoenergetic electrons, positrons, and alpha particles. The tumor and normal tissue were assumed to be of water density. The activity concentration ratio between the tumor and normal tissue was assumed to be 25. The radionuclides emitting low-energy electrons combined with a low photon contribution, and the alpha emitters showed high TND values for most tumor sizes. Electrons with higher energy gave reduced TND values for small tumors, while a higher photon contribution reduced the TND values for large tumors. Radionuclides with high photon contributions showed low TND value for all tumor sizes studied. The radionuclides studied could be divided into four main groups according to their TND values: beta emitters, Auger electron

  8. Single photon transport by a moving atom

    International Nuclear Information System (INIS)

    Afanasiev, A E; Melentiev, P N; Kuzin, A A; Yu Kalatskiy, A; Balykin, V I

    2017-01-01

    The results of investigation of photon transport through the subwavelength hole in the opaque screen by using single neutral atom are represented. The basis of the proposed and implemented method is the absorption of a photon by a neutral atom immediately before the subwavelength aperture, traveling of the atoms through the hole and emission of a photon on the other side of the screen. Realized method is the alternative approach to existing for photon transport through a subwavelength aperture: 1) self-sustained transmittance of a photon through the aperture according to the Bethe’s model; 2) extra ordinary transmission because of surface-plasmon excitation. (paper)

  9. A Successful Attempt to Obtain the Linear Dependence Between One-Photon and Two-Photon Spectral Properties and Hammett Parameters of Various Aromatic Substituents in New π-Extended Asymmetric Organic Chromophores.

    Science.gov (United States)

    Hu, Nvdan; Gong, Yulong; Wang, Xinchao; Lu, Yao; Peng, Guangyue; Yang, Long; Zhang, Shengtao; Luo, Ziping; Li, Hongru; Gao, Fang

    2015-11-01

    A series of new asymmetric chromophores containing aromatic substituents and possessing the excellent π-extension in space were prepared through multi-steps routes. One-photon and two-photon spectral properties of these new chromophores could be tuned by these substituents finely and simultaneously. The linear correlation of the wave numbers of the one-photon absorption and emission maxima to Hammett parameters of these substituents was presented. Near infrared two-photon absorption emission integrated areas of the target chromophores were correlated linearly to Hammett constants of these substituted groups.

  10. Method to deterministically study photonic nanostructures in different experimental instruments.

    Science.gov (United States)

    Husken, B H; Woldering, L A; Blum, C; Vos, W L

    2009-01-01

    We describe an experimental method to recover a single, deterministically fabricated nanostructure in various experimental instruments without the use of artificially fabricated markers, with the aim to study photonic structures. Therefore, a detailed map of the spatial surroundings of the nanostructure is made during the fabrication of the structure. These maps are made using a series of micrographs with successively decreasing magnifications. The graphs reveal intrinsic and characteristic geometric features that can subsequently be used in different setups to act as markers. As an illustration, we probe surface cavities with radii of 65 nm on a silica opal photonic crystal with various setups: a focused ion beam workstation; a scanning electron microscope (SEM); a wide field optical microscope and a confocal microscope. We use cross-correlation techniques to recover a small area imaged with the SEM in a large area photographed with the optical microscope, which provides a possible avenue to automatic searching. We show how both structural and optical reflectivity data can be obtained from one and the same nanostructure. Since our approach does not use artificial grids or markers, it is of particular interest for samples whose structure is not known a priori, like samples created solely by self-assembly. In addition, our method is not restricted to conducting samples.

  11. Excitation enhancement and extraction enhancement with photonic crystals

    Science.gov (United States)

    Shapira, Ofer; Soljacic, Marin; Zhen, Bo; Chua, Song-Liang; Lee, Jeongwon; Joannopoulos, John

    2015-03-03

    Disclosed herein is a system for stimulating emission from at least one an emitter, such as a quantum dot or organic molecule, on the surface of a photonic crystal comprising a patterned dielectric substrate. Embodiments of this system include a laser or other source that illuminates the emitter and the photonic crystal, which is characterized by an energy band structure exhibiting a Fano resonance, from a first angle so as to stimulate the emission from the emitter at a second angle. The coupling between the photonic crystal and the emitter may result in spectral and angular enhancement of the emission through excitation and extraction enhancement. These enhancement mechanisms also reduce the emitter's lasing threshold. For instance, these enhancement mechanisms enable lasing of a 100 nm thick layer of diluted organic molecules solution with reduced threshold intensity. This reduction in lasing threshold enables more efficient organic light emitting devices and more sensitive molecular sensing.

  12. Hard photons and mesons as probes of heavy ion collision dynamics

    International Nuclear Information System (INIS)

    Metag, V.

    1991-01-01

    Hard photon production in heavy ion collisions has been studied by a large number of groups at various laboratory and a large body of data has been collected. Recent results reviewed are summarized here in a systematics for photon emission. A brief discussion of π 0 -production in heavy ion collisions will be given including first results with the Two Arm Photon spectrometer TAPS obtained at SIS. Furthermore, the new perspectives for the study of compressed nuclear matter by meson emission will be outlined. (orig.)

  13. Semiconductor quantum optics with tailored photonic nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Laucht, Arne

    2011-06-15

    This thesis describes detailed investigations of the effects of photonic nanostructures on the light emission properties of self-assembled InGaAs quantum dots. Nanoscale optical cavities and waveguides are employed to enhance the interaction between light and matter, i.e. photons and excitons, up to the point where optical non-linearities appear at the quantum (single photon) level. Such non-linearities are an essential component for the realization of hardware for photon based quantum computing since they can be used for the creation and detection of non-classical states of light and may open the way to new genres of quantum optoelectronic devices such as optical modulators and optical transistors. For single semiconductor quantum dots in photonic crystal nanocavities we investigate the coupling between excitonic transitions and the highly localized mode of the optical cavity. We explore the non-resonant coupling mechanisms which allow excitons to couple to the cavity mode, even when they are not spectrally in resonance. This effect is not observed for atomic cavity quantum electrodynamics experiments and its origin is traced to phonon-assisted scattering for small detunings ({delta}E<{proportional_to}5 meV) and a multi-exciton-based, Auger-like process for larger detunings ({delta}E >{proportional_to}5 meV). For quantum dots in high-Q cavities we observe the coherent coupling between exciton and cavity mode in the strong coupling regime of light-matter interaction, probe the influence of pure dephasing on the coherent interaction at high excitation levels and high lattice temperatures, and examine the coupling of two spatially separated quantum dots via the exchange of real and virtual photons mediated by the cavity mode. Furthermore, we study the spontaneous emission properties of quantum dots in photonic crystal waveguide structures, estimate the fraction of all photons emitted into the propagating waveguide mode, and demonstrate the on-chip generation of

  14. Spectrum of a one-atom laser in photonic crystals

    International Nuclear Information System (INIS)

    Florescu, Lucia

    2006-01-01

    The emission spectrum of a single-emitter laser in a photonic crystal is presented. We consider a coherently pumped two-level emitter strongly coupled to a high-quality microcavity engineered within a photonic crystal. We show that the cavity spectrum consists of both elastic and inelastic components, for which we derive analytical expressions. Our study reveals enhanced, spectrally narrower emission resulting from the radiation reservoir of the photonic crystal. The cavity field spectral characteristics are fundamentally distinct from those of a corresponding microcavity in ordinary vacuum. At high pump intensities and for large discontinuities in the photon density of states between Mollow spectral components of atomic resonance fluorescence, the emitted intensity originating from the elastic spectral component increases with the intensity of the pump and the elastic component dominates the spectrum. In the case of a vanishing photon density of states in the spectral range surrounding the lower Mollow sideband and no dipolar dephasing, the cavity spectrum is elastic

  15. An analysis of regional cerebral blood flow in impulsive murderers using single photon emission computed tomography.

    Science.gov (United States)

    Amen, Daniel G; Hanks, Chris; Prunella, Jill R; Green, Aisa

    2007-01-01

    The authors explored differences in regional cerebral blood flow in 11 impulsive murderers and 11 healthy comparison subjects using single photon emission computed tomography. The authors assessed subjects at rest and during a computerized go/no-go concentration task. Using statistical parametric mapping software, the authors performed voxel-by-voxel t tests to assess significant differences, making family-wide error corrections for multiple comparisons. Murderers were found to have significantly lower relative rCBF during concentration, particularly in areas associated with concentration and impulse control. These results indicate that nonemotionally laden stimuli may result in frontotemporal dysregulation in people predisposed to impulsive violence.

  16. Calculation of spontaneous emission from a V-type three-level atom in photonic crystals using fractional calculus

    International Nuclear Information System (INIS)

    Huang, Chih-Hsien; Hsieh, Wen-Feng; Wu, Jing-Nuo; Cheng, Szu-Cheng; Li, Yen-Yin

    2011-01-01

    Fractional time derivative, an abstract mathematical operator of fractional calculus, is used to describe the real optical system of a V-type three-level atom embedded in a photonic crystal. A fractional kinetic equation governing the dynamics of the spontaneous emission from this optical system is obtained as a fractional Langevin equation. Solving this fractional kinetic equation by fractional calculus leads to the analytical solutions expressed in terms of fractional exponential functions. The accuracy of the obtained solutions is verified through reducing the system into the special cases whose results are consistent with the experimental observation. With accurate physical results and avoiding the complex integration for solving this optical system, we propose fractional calculus with fractional time derivative as a better mathematical method to study spontaneous emission dynamics from the optical system with non-Markovian dynamics.

  17. Multi-photon microscope driven by novel green laser pump

    Science.gov (United States)

    Marti, Dominik; Djurhuus, Martin; Jensen, Ole Bjarlin; Andersen, Peter E.

    2016-03-01

    Multi-photon microscopy is extensively used in research due to its superior possibilities when compared to other microscopy modalities. The technique also has the possibility to advance diagnostics in clinical applications, due to its capabilities complementing existing technology in a multimodal system. However, translation is hindered due to the high cost, high training demand and large footprint of a standard setup. We show in this article that minification of the setup, while also reducing cost and complexity, is indeed possible without compromising on image quality, by using a novel diode laser replacing the commonly used conventional solid state laser as the pump for the femtosecond system driving the imaging.

  18. Quantum photonics

    CERN Document Server

    Pearsall, Thomas P

    2017-01-01

    This textbook employs a pedagogical approach that facilitates access to the fundamentals of Quantum Photonics. It contains an introductory description of the quantum properties of photons through the second quantization of the electromagnetic field, introducing stimulated and spontaneous emission of photons at the quantum level. Schrödinger’s equation is used to describe the behavior of electrons in a one-dimensional potential. Tunneling through a barrier is used to introduce the concept of non­locality of an electron at the quantum level, which is closely-related to quantum confinement tunneling, resonant tunneling, and the origin of energy bands in both periodic (crystalline) and aperiodic (non-crystalline) materials. Introducing the concepts of reciprocal space, Brillouin zones, and Bloch’s theorem, the determination of electronic band structure using the pseudopotential method is presented, allowing direct computation of the band structures of most group IV, group III-V, and group II-VI semiconducto...

  19. The peculiarities of regional volume cerebral blood flow in patients with hypertensive encephalopathy by the findings of single photon emission computed tomography

    International Nuclear Information System (INIS)

    Makejev, S.S.; Novyikova, T.G.; Kustkova, A.S.

    2012-01-01

    The investigation of the state of the brain perfusion in patients with stage II hypertensive encephalopathy (HE) at development of hypertension crisis vs. crisis-free course of HE showed that in 79,5% of the patients with stage II HE, single photon emission computed tomography demonstrated local changes of the blood flow

  20. Ghost imaging with paired x-ray photons

    Science.gov (United States)

    Schori, A.; Borodin, D.; Tamasaku, K.; Shwartz, S.

    2018-06-01

    We report the experimental observation of ghost imaging with paired x-ray photons, which are generated by parametric downconversion. We use the one-to-one relation between the photon energies and the emission angles and the anticorrelation between the k -vectors of the signal and the idler photons to reconstruct the images of slits with nominally zero background levels. Further extension of our procedure can be used for the observation of various quantum phenomena at x-ray wavelengths.

  1. Near-field probing of photonic crystal directional couplers

    DEFF Research Database (Denmark)

    Volkov, V. S.; Bozhevolnyi, S. I.; Borel, Peter Ingo

    2006-01-01

    We report the design, fabrication and characterization of a photonic crystal directional with a size of ~20 x 20 mm2 fabricated in silicon-on-insulator material. Using a scanning near-field optical microscope we demonstrate a high coupling efficiency for TM polarized light at telecom wavelengths....... By comparing the near-field optical images recorded in and after the directional coupler area, the features of light distribution are analyzed. Finally, the scanning near-field optical microscope observations are found to be in agreement with the transmission measurements conducted with the same sample....

  2. Negative space charge effects in photon-enhanced thermionic emission solar converters

    International Nuclear Information System (INIS)

    Segev, G.; Weisman, D.; Rosenwaks, Y.; Kribus, A.

    2015-01-01

    In thermionic energy converters, electrons in the gap between electrodes form a negative space charge and inhibit the emission of additional electrons, causing a significant reduction in conversion efficiency. However, in Photon Enhanced Thermionic Emission (PETE) solar energy converters, electrons that are reflected by the electric field in the gap return to the cathode with energy above the conduction band minimum. These electrons first occupy the conduction band from which they can be reemitted. This form of electron recycling makes PETE converters less susceptible to negative space charge loss. While the negative space charge effect was studied extensively in thermionic converters, modeling its effect in PETE converters does not account for important issues such as this form of electron recycling, nor the cathode thermal energy balance. Here, we investigate the space charge effect in PETE solar converters accounting for electron recycling, with full coupling of the cathode and gap models, and addressing conservation of both electric and thermal energy. The analysis shows that the negative space charge loss is lower than previously reported, allowing somewhat larger gaps compared to previous predictions. For a converter with a specific gap, there is an optimal solar flux concentration. The optimal solar flux concentration, the cathode temperature, and the efficiency all increase with smaller gaps. For example, for a gap of 3 μm the maximum efficiency is 38% and the optimal flux concentration is 628, while for a gap of 5 μm the maximum efficiency is 31% and optimal flux concentration is 163

  3. The distribution of cerebral muscarinic acetylcholine receptors in vivo in patients with dementia. A controlled study with 123IQNB and single photon emission computed tomography

    International Nuclear Information System (INIS)

    Weinberger, D.R.; Gibson, R.; Coppola, R.; Jones, D.W.; Molchan, S.; Sunderland, T.; Berman, K.F.; Reba, R.C.

    1991-01-01

    A high-affinity muscarinic receptor antagonist, 123IQNB (3-quinuclidinyl-4-iodobenzilate labeled with iodine 123), was used with single photon emission computed tomography to image muscarinic acetylcholine receptors in 14 patients with dementia and in 11 healthy controls. High-resolution single photon emission computed tomographic scanning was performed 21 hours after the intravenous administration of approximately 5 mCi of IQNB. In normal subjects, the images of retained ligand showed a consistent regional pattern that correlated with postmortem studies of the relative distribution of muscarinic receptors in the normal human brain, having high radioactivity counts in the basal ganglia, occipital cortex, and insular cortex, low counts in the thalamus, and virtually no counts in the cerebellum. Eight of 12 patients with a clinical diagnosis of Alzheimer's disease had obvious focal cortical defects in either frontal or posterior temporal cortex. Both patients with a clinical diagnosis of Pick's disease had obvious frontal and anterior temporal defects. A region of interest statistical analysis of relative regional activity revealed a significant reduction bilaterally in the posterior temporal cortex of the patients with Alzheimer's disease compared with controls. This study demonstrates the practicability of acetylcholine receptor imaging with 123IQNB and single photon emission computed tomography. The data suggest that focal abnormalities in muscarinic binding in vivo may characterize some patients with Alzheimer's disease and Pick's disease, but further studies are needed to address questions about partial volume artifacts and receptor quantification

  4. A scanner for single photon emission tomography

    International Nuclear Information System (INIS)

    Smith, D.B.; Cumpstey, D.E.; Evans, N.T.S.; Coleman, J.D.; Ettinger, K.V.; Mallard, J.R.

    1982-01-01

    The technique of single photon ECT has now been available for some eighteen years, but has yet still to be exploited fully. The difficulties of doing this lie in the need for gathering data of sufficiently good statistical accuracy in a reasonable counting time, in the uniformity of detector sensitivity, and in the means for correcting the image satisfactorily for photon attenuation within the body. The relative ease with which a general purpose gamma camera can be adapted to give rotation around the patient makes this an attractive practical approach to the problem. However, the sensitivity of gamma cameras over their field of view is by no means uniform, and their sensitivity is less good than that of purpose-designed scanners when no more than about ten sections through the body are required. There is therefore a need to assess the clinical usefulness of a whole body tomographic scanner of high sensitivity and uniformity. Such a machine is the Aberdeen Section Scanner Mark II described

  5. A PVTC system integrating photon-enhanced thermionic emission and methane reforming for efficient solar power generation

    Institute of Scientific and Technical Information of China (English)

    Wenjia Li; Hongsheng Wang; Yong Hao

    2017-01-01

    A new photovoltaic-thermochemical (PVTC) conceptual system integrating photon-enhanced thermionic emission (PETE) and methane steam reforming is proposed.Major novelty of the system lies in its potential adaptivity to primary fuels (e.g.methane) and high efficiencies of photovoltaic and thermochemical power generation,both of which result from its operation at much elevated temperatures (700-1000 ℃)compared with conventional photovoltaic-thermal (PVT) systems.Analysis shows that an overall power generation efficiency of 45.3% and a net solar-to-electric efficiency of 39.1% could be reached at an operating temperature of 750 ℃,after considering major losses during solar energy capture and conversion processes.The system is also featured by high solar share (37%) in the total power output,as well as high energy storage capability and very low CO2 emissions,both enabled by the integration of methane reforming with photovoltaic generation at high temperatures.

  6. Calibration of a microscopic simulation model for emission calculation

    NARCIS (Netherlands)

    Jie, L.; Zuylen, H. van; Chen, Y.; Viti, F.; Wilmink, I.

    2013-01-01

    Emissions by road traffic can be reduced by optimising traffic control. The impact of this optimisation on emission can be analysed ex ante by simulation. The simulation programs used for this analysis should be valid with respect to the traffic characteristics that determine the emissions. Thus

  7. Free-standing GaN grating couplers and rib waveguide for planar photonics at telecommunication wavelength

    Science.gov (United States)

    Liu, Qifa; Wang, Wei

    2018-01-01

    Gallium Nitride (GaN) free-standing planar photonic device at telecommunication wavelength based on GaN-on-silicon platform was presented. The free-standing structure was realized by particular double-side fabrication process, which combining GaN front patterning, Si substrate back releasing and GaN slab etching. The actual device parameters were identified via the physical characterizations employing scanning electron microscope (SEM), atomic force microscope (AFM) and reflectance spectra testing. High coupling efficiency and good light confinement properties of the gratings and rib waveguide at telecommunication wavelength range were verified by finite element method (FEM) simulation. This work illustrates the potential of new GaN photonic structure which will enable new functions for planar photonics in communication and sensing applications, and is favorable for the realization of integrated optical circuit.

  8. Higher-order photon bunching in a semiconductor microcavity

    DEFF Research Database (Denmark)

    Assmann, M.; Veit, F.; Bayer, M.

    2009-01-01

    Quantum mechanically indistinguishable particles such as photons may show collective behavior. Therefore, an appropriate description of a light field must consider the properties of an assembly of photons instead of independent particles. We have studied multiphoton correlations up to fourth order...... in the single-mode emission of a semiconductor microcavity in the weak and strong coupling regimes. The counting statistics of single photons were recorded with picosecond time resolution, allowing quantitative measurement of the few-photon bunching inside light pulses. Our results show bunching behavior...

  9. Two-photon decay in heavy atoms and ions

    International Nuclear Information System (INIS)

    Mokler, P.H.; Dunford, R.W

    2003-08-01

    We review the status of and comment on current developments in the field of two-photon decay in atomic physics research. Recent work has focused on two-photon decays in highly-charged ions and two-photon decay of inner-shell vacancies in heavy neutral atoms. We emphasize the importance of measuring the shape of the continuum emission in two-photon decay as a probe of relativistic effects in the strong central fields found in heavy atomic systems. New experimental approaches and their consequences will be discussed. (orig.)

  10. The ENDF/B-VI photon interaction library

    International Nuclear Information System (INIS)

    Cullen, D.E.; Perkins, S.T.; Plechaty, E.F.

    1992-02-01

    The ENDF/B-VI photon interaction library includes data to describe the interaction of photons with the elements Z = 1 to 100 over the energy range 10 eV to 100 MeV. This library has been designed to meet the traditional needs of users to model the interaction and transport of primary photons. However, this library contains additional information which used in a combination with our other data libraries can be used to perform much more detailed calculations, e.g., emission of secondary fluorescence photons. This paper describes both traditional and more detailed uses of this library

  11. Hybrid methods for witnessing entanglement in a microscopic-macroscopic system

    International Nuclear Information System (INIS)

    Spagnolo, Nicolo; Vitelli, Chiara; Paternostro, Mauro; De Martini, Francesco; Sciarrino, Fabio

    2011-01-01

    We propose a hybrid approach to the experimental assessment of the genuine quantum features of a general system consisting of microscopic and macroscopic parts. We infer entanglement by combining dichotomic measurements on a bidimensional system and phase-space inference through the Wigner distribution associated with the macroscopic component of the state. As a benchmark, we investigate the feasibility of our proposal in a bipartite-entangled state composed of a single-photon and a multiphoton field. Our analysis shows that, under ideal conditions, maximal violation of a Clauser-Horne-Shimony-Holt-based inequality is achievable regardless of the number of photons in the macroscopic part of the state. The difficulty in observing entanglement when losses and detection inefficiency are included can be overcome by using a hybrid entanglement witness that allows efficient correction for losses in the few-photon regime.

  12. Hybrid methods for witnessing entanglement in a microscopic-macroscopic system

    Energy Technology Data Exchange (ETDEWEB)

    Spagnolo, Nicolo [Dipartimento di Fisica, Sapienza Universita di Roma, Piazzale Aldo Moro 5, I-00185 Roma (Italy); Consorzio Nazionale Interuniversitario per le Scienze Fisiche della Materia, Piazzale Aldo Moro 5, I-00185 Roma (Italy); Vitelli, Chiara [Dipartimento di Fisica, Sapienza Universita di Roma, Piazzale Aldo Moro 5, I-00185 Roma (Italy); Paternostro, Mauro [School of Mathematics and Physics, Queen' s University, BT 7 1NN Belfast (United Kingdom); De Martini, Francesco [Dipartimento di Fisica, Sapienza Universita di Roma, Piazzale Aldo Moro 5, I-00185 Roma (Italy); Accademia Nazionale dei Lincei, via della Lungara 10, I-00165 Roma (Italy); Sciarrino, Fabio [Dipartimento di Fisica, Sapienza Universita di Roma, Piazzale Aldo Moro 5, I-00185 Roma (Italy); Istituto Nazionale di Ottica, Consiglio Nazionale delle Ricerche (INO-CNR), largo E. Fermi 6, I-50125 Firenze (Italy)

    2011-09-15

    We propose a hybrid approach to the experimental assessment of the genuine quantum features of a general system consisting of microscopic and macroscopic parts. We infer entanglement by combining dichotomic measurements on a bidimensional system and phase-space inference through the Wigner distribution associated with the macroscopic component of the state. As a benchmark, we investigate the feasibility of our proposal in a bipartite-entangled state composed of a single-photon and a multiphoton field. Our analysis shows that, under ideal conditions, maximal violation of a Clauser-Horne-Shimony-Holt-based inequality is achievable regardless of the number of photons in the macroscopic part of the state. The difficulty in observing entanglement when losses and detection inefficiency are included can be overcome by using a hybrid entanglement witness that allows efficient correction for losses in the few-photon regime.

  13. Multisite two-photon imaging of neurons on multielectrode arrays

    Science.gov (United States)

    Potter, Steve M.; Lukina, Natalia; Longmuir, Kenneth J.; Wu, Yan

    2001-04-01

    We wish to understand how neural systems store, recall, and process information. We are using cultured networks of cortical neurons grown on microelectrode arrays as a model system for studying the emergent properties of ensembles of living neurons. We have developed a 2-way communication interface between the cultured network and a computer- generated animal, the Neurally Controlled Animat. Neural activity is used to control the behavior of the Animat, and 2- photon time-lapse imaging is carried out in order to observe the morphological changes that might underlie changes in neural processing. The 2-photon microscope is ideal for repeated imaging over hours or days, with submicron resolution and little photodamage. We have designed a computer-controlled microscope stage that allows imaging several locations in sequence, in order to collect more image data. For the latest progress, see: http://www.caltech.edu/~pinelab/PotterGroup.htm.

  14. Near-field characterization of photonic crystal Y-splitters

    DEFF Research Database (Denmark)

    Volkov, V. S.; Bozhevolnyi, S. I.; Borel, Peter Ingo

    2005-01-01

    A scanning near-field optical microscope (SNOM) is used to directly map the propagation of light in a specially designed 50/50 photonic crystal (PC) Y-splitter fabricated on silicon-on-insulator (SOI) wafers. SNOM images are obtained for TE- and TM-polarized light in the wavelength range 1425...

  15. Development of remote controlled type field-emission type scanning electron microscope

    Energy Technology Data Exchange (ETDEWEB)

    Yasuda, Ryo; Nishino, Yasuharu; Mita, Naoaki; Nakata, Masahito; Harada, Katsuya; Nozawa, Yukio; Amano, Hidetoshi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    2002-10-01

    The extending burn-up of Light Water Reactor Fuels has been promoted to reduce costs of the power generation and amount of waste mass. Information about the fuel behavior under high burn-up operation is needed to assess safety of the high burn-up fuels. Microstructures formed in high burn-up fuel pellets and Zircaloy tubes influence on their integrity. The fundamental information about morphology, sizes, and element compositions in those microstructures is necessary to estimate the formation mechanism and change in the properties of the fuels. The Field Emission type Scanning Electron Microscope (FE-SEM), which is effective for observation of very small area, i.e., nano-size structures, has been hence installed at the Reactor Fuel Examination Facility (RFEF) in JAERI. FE-SEM is designed for the remote handling type to use high radioactive materials and has equipments to keep the safety for operators. The Energy Dispersive Spectrometer (EDS) with a radiation-shielding collimator has been also equipped on FE-SEM to determine element compositions in the structures. Characterization tests were carried out using Zircaloy cladding tubes with oxide films and hydrides of confirm machine performance. In the results of the tests, high-resolution images with a magnification of 30,000 were obtained. Those results show that the apparatus maintains the original high performance with standard type. (author)

  16. Microscopic imaging through turbid media Monte Carlo modeling and applications

    CERN Document Server

    Gu, Min; Deng, Xiaoyuan

    2015-01-01

    This book provides a systematic introduction to the principles of microscopic imaging through tissue-like turbid media in terms of Monte-Carlo simulation. It describes various gating mechanisms based on the physical differences between the unscattered and scattered photons and method for microscopic image reconstruction, using the concept of the effective point spread function. Imaging an object embedded in a turbid medium is a challenging problem in physics as well as in biophotonics. A turbid medium surrounding an object under inspection causes multiple scattering, which degrades the contrast, resolution and signal-to-noise ratio. Biological tissues are typically turbid media. Microscopic imaging through a tissue-like turbid medium can provide higher resolution than transillumination imaging in which no objective is used. This book serves as a valuable reference for engineers and scientists working on microscopy of tissue turbid media.

  17. Linear Gain and Gain Saturation in a Photonic Free-Electron Laser

    NARCIS (Netherlands)

    Denis, T.; Boller, Klaus J.; Lee, J.H.H.; van der Slot, P.J.M.; van Dijk, Marc

    2012-01-01

    Photonic crystals are used to manipulate the generation of light, for example, stimulated emission can be enhanced. A photonic free-electron laser (pFEL) applies this enhancement to generate widely tunable coherent Cerenkov radiation from low energy electrons (keV) streaming through the photonic

  18. Long-Distance Single Photon Transmission from a Trapped Ion via Quantum Frequency Conversion

    Science.gov (United States)

    Walker, Thomas; Miyanishi, Koichiro; Ikuta, Rikizo; Takahashi, Hiroki; Vartabi Kashanian, Samir; Tsujimoto, Yoshiaki; Hayasaka, Kazuhiro; Yamamoto, Takashi; Imoto, Nobuyuki; Keller, Matthias

    2018-05-01

    Trapped atomic ions are ideal single photon emitters with long-lived internal states which can be entangled with emitted photons. Coupling the ion to an optical cavity enables the efficient emission of single photons into a single spatial mode and grants control over their temporal shape. These features are key for quantum information processing and quantum communication. However, the photons emitted by these systems are unsuitable for long-distance transmission due to their wavelengths. Here we report the transmission of single photons from a single 40Ca+ ion coupled to an optical cavity over a 10 km optical fiber via frequency conversion from 866 nm to the telecom C band at 1530 nm. We observe nonclassical photon statistics of the direct cavity emission, the converted photons, and the 10 km transmitted photons, as well as the preservation of the photons' temporal shape throughout. This telecommunication-ready system can be a key component for long-distance quantum communication as well as future cloud quantum computation.

  19. Detection of avascular necrosis in adults by single photon emission computed tomography

    International Nuclear Information System (INIS)

    Collier, B.D.; Johnston, R.P.; Carrera, G.; Isitman, A.T.; Hellman, R.S.; Zielonka, J.S.

    1984-01-01

    Twenty-one adult patients with the clinical diagnosis of avascular necrosis (AVN) of the femoral head were examined with planar bone scintigraphy (high resolution collimator) and single photon emission computed tomography (SPECT). The duration of hip pain ranged from 1 day to 18 months. Risk factors (including steroids, renal transplantation, alcoholism, and trauma) were present in 17 cases. A final diagnosis of AVN (20 hips), osteochondral facture, or stress fracture, was established for 17 patients. The 4 remaining patients, who were radiographically normal and did not complain of pain 3 months later, were thought to have no significant bone pathology. SPECT and planar bone scintigraphy were reported as positive for AVN only if a photopenic bony defect could be identified. In particular, uniformly increased activity throughout the femoral head was not considered to be diagnostic of AVN. The authors conclude that by identifying a photopenic defect which is not evident on planar bone scintigraphy, SPECT can contribute to accurate diagnosis of AVN

  20. Few-Photon Multiple Ionization of Ne and Ar by Strong Free-Electron-Laser Pulses

    International Nuclear Information System (INIS)

    Moshammer, R.; Jiang, Y. H.; Rudenko, A.; Ergler, Th.; Schroeter, C. D.; Luedemann, S.; Zrost, K.; Dorn, A.; Ferger, T.; Kuehnel, K. U.; Ullrich, J.; Foucar, L.; Titze, J.; Jahnke, T.; Schoeffler, M.; Doerner, R.; Fischer, D.; Weber, T.; Zouros, T. J. M.; Duesterer, S.

    2007-01-01

    Few-photon multiple ionization of Ne and Ar atoms by strong vacuum ultraviolet laser pulses from the free-electron laser at Hamburg was investigated differentially with the Heidelberg reaction microscope. The light-intensity dependence of Ne 2+ production reveals the dominance of nonsequential two-photon double ionization at intensities of I 12 W/cm 2 and significant contributions of three-photon ionization as I increases. Ne 2+ recoil-ion-momentum distributions suggest that two electrons absorbing ''instantaneously'' two photons are ejected most likely into opposite hemispheres with similar energies

  1. Resting state rCBF mapping with single-photon emission tomography and positron emission tomography: magnitude and origin of differences

    International Nuclear Information System (INIS)

    Jonsson, C.; Kimiaei, S.; Larsson, S.A.; Pagani, M.; Ingvar, M.; Thurfjell, L.; Jacobsson, H.

    1998-01-01

    Single-photon emission tomography (SPET), using technetium-99m hexamethylpropylene amine oxime, and positron emission tomography (PET), using oxygen-15 butanol were compared in six healthy male volunteers with regard to the mapping of resting state regional cerebral blood flow (rCBF). A computerized brain atlas was utilized for 3D regional analyses and comparison of 64 selected and normalized volumes of interest (VOIs). The normalized mean rCBF values in SPET, as compared to PET, were higher in most of the Brodmann areas in the frontal and parietal lobes (4.8% and 8.7% respectively). The average differences were small in the temporal (2.3%) and occipital (1.1%) lobes. PET values were clearly higher in small VOIs like the thalamus (12.3%), hippocampus (12.3%) and basal ganglia (9.9%). A resolution phantom study showed that the in-plane SPET/PET system resolution was 11.0/7.5 mm. In conclusion, SPET and PET data demonstrated a fairly good agreement despite the superior spatial resolution of PET. The differences between SPET and PET rCBF are mainly due to physiological and physical factors, the data processing, normalization and co-registration methods. In order to further improve mapping of rCBF with SPET it is imperative not only to improve the spatial resolution but also to apply accurate correction techniques for scatter, attenuation and non-linear extraction. (orig.)

  2. Highly efficient sources of single indistinguishable photons

    DEFF Research Database (Denmark)

    Gregersen, Niels

    2013-01-01

    be electrically driven. Several design strategies addressing these requirements have been proposed. In the cavity-based source, light emission is controlled using resonant cavity quantum electrodynamics effects, whereas in the waveguide-based source, broadband electric field screening effects are employed......Solid-state sources capable of emitting single photons on demand are of great interest in quantum information applications. Ideally, such a source should emit exactly one photon into the collection optics per trigger, the emitted photons should be indistinguishable and the source should...

  3. Quantitative measurements with x-ray microscopes in laser-fusion experiments

    International Nuclear Information System (INIS)

    Marshall, F.J.; Su, Q.

    1995-01-01

    X-ray imaging of laser-fusion target implosions has been performed on the University of Rochester's OMEGA laser system by means of grazing-incidence optical imaging with Kirkpatrick--Baez (KB) microscopes. High spatial resolution imaging (∼5 μm) of hard x-ray emission (up to ∼7 keV) has been achieved. New grazing-incidence optics are currently being fabricated for the OMEGA Upgrade experimental laser-fusion facility. Projected performance indicates that resolution may be increased to ∼2 μm at the center of the field of view and sensitivity extended to ∼8 keV. Uses of KB microscopes on the OMEGA Upgrade will include hard x-ray imaging, grating-dispersed imaged spectroscopy, and framed imaging. A novel technique for monochromatic imaging with KB microscopes has also been demonstrated enabling images of target emission in a narrow energy band (10 to 20 eV) to be obtained

  4. A new Scanning Transmission X-ray Microscope at the ALS for operation up to 2500eV

    International Nuclear Information System (INIS)

    Kilcoyne, David; Ade, Harald; Attwood, David; Hitchcock, Adam; McKean, Pat; Mitchell, Gary; Monteiro, Paulo; Tyliszczak, Tolek; Warwick, Tony

    2010-01-01

    We report on the design and construction of a higher energy Scanning Transmission X-ray Microscope on a new bend magnet beam line at the Advanced Light Source. Previously we have operated such an instrument on a bend magnet for C, N and O 1s NEXAFS spectroscopy. The new instrument will have similar performance at higher energies up to and including the S 1s edge at 2472eV. A new microscope configuration is planned. A more open geometry will allow a fluorescence detector to count emitted photons from the front surface of the sample. There will be a capability for zone plate scanning in addition to the more conventional sample scanning mode. This will add the capability for imaging a massive sample at high resolution over a limited field of view, so that heavy reaction cells may be used to study processes in-situ, exploiting the longer photon attenuation length and the longer zone plate working distances available at higher photon energy. The energy range will extend down to include the C1s edge at 300eV, to allow high energy NEXAFS microscopic studies to correlate with the imaging of organics in the same sample region of interest.

  5. Theory of fluorescence in photonic crystals

    International Nuclear Information System (INIS)

    Vats, Nipun; John, Sajeev; Busch, Kurt

    2002-01-01

    We present a formalism for the description of fluorescence from optically active materials embedded in a photonic crystal structure possessing a photonic band gap or pseudogap. An electromagnetic field expansion in terms of Bloch modes of the crystal is used to develop the equations for fluorescence in terms of the local density of photon modes available to the emitting atoms in either the high or low dielectric regions of the crystal. We then obtain expressions for fluorescence spectra and emission dynamics for luminescent materials in photonic crystals. The validity of our formalism is demonstrated through the calculation of relevant quantities for model photon densities of states. The connection of our calculations to the description of realistic systems is discussed. We also describe the consequences of these analyses on the accurate description of the interaction between radiative systems and the electromagnetic reservoir within photonic crystals

  6. Self-consistent Maxwell-Bloch theory of quantum-dot-population switching in photonic crystals

    International Nuclear Information System (INIS)

    Takeda, Hiroyuki; John, Sajeev

    2011-01-01

    We theoretically demonstrate the population switching of quantum dots (QD's), modeled as two-level atoms in idealized one-dimensional (1D) and two-dimensional (2D) photonic crystals (PC's) by self-consistent solution of the Maxwell-Bloch equations. In our semiclassical theory, energy states of the electron are quantized, and electron dynamics is described by the atomic Bloch equation, while electromagnetic waves satisfy the classical Maxwell equations. Near a waveguide cutoff in a photonic band gap, the local electromagnetic density of states (LDOS) and spontaneous emission rates exhibit abrupt changes with frequency, enabling large QD population inversion driven by both continuous and pulsed optical fields. We recapture and generalize this ultrafast population switching using the Maxwell-Bloch equations. Radiative emission from the QD is obtained directly from the surrounding PC geometry using finite-difference time-domain simulation of the electromagnetic field. The atomic Bloch equations provide a source term for the electromagnetic field. The total electromagnetic field, consisting of the external input and radiated field, drives the polarization components of the atomic Bloch vector. We also include a microscopic model for phonon dephasing of the atomic polarization and nonradiative decay caused by damped phonons. Our self-consistent theory captures stimulated emission and coherent feedback effects of the atomic Mollow sidebands, neglected in earlier treatments. This leads to remarkable high-contrast QD-population switching with relatively modest (factor of 10) jump discontinuities in the electromagnetic LDOS. Switching is demonstrated in three separate models of QD's placed (i) in the vicinity of a band edge of a 1D PC, (ii) near a cutoff frequency in a bimodal waveguide channel of a 2D PC, and (iii) in the vicinity of a localized defect mode side coupled to a single-mode waveguide channel in a 2D PC.

  7. Evaluation of a 99Tcm bound brain scanning agent for single photon emission computed tomography

    DEFF Research Database (Denmark)

    Andersen, A R; Hasselbalch, S G; Paulson, O B

    1986-01-01

    D,L HM-PAO-99Tcm (PAO) is a lipophilic tracer complex which is avidly taken up by the brain. We have compared the regional distribution of PAO with regional cerebral blood flow (CBF). CBF was measured by single photon emission computed tomography (SPECT) by Tomomatic 64 after 133Xe inhalation in 41...... patients. With the same SPECT the distribution of PAO was measured after intravenous injection. High resolution (HR) and low resolution (LR) studies were performed yielding a resolution of 6-10 mm (HR) and 15-20 mm (LR). PAO images showed close resemblance to 133Xe CBF tomograms. Only 20 per cent...... of the (decay corrected) brain counts were lost during 24 hours....

  8. Photon-photon scattering at the high-intensity frontier

    Science.gov (United States)

    Gies, Holger; Karbstein, Felix; Kohlfürst, Christian; Seegert, Nico

    2018-04-01

    The tremendous progress in high-intensity laser technology and the establishment of dedicated high-field laboratories in recent years have paved the way towards a first observation of quantum vacuum nonlinearities at the high-intensity frontier. We advocate a particularly prospective scenario, where three synchronized high-intensity laser pulses are brought into collision, giving rise to signal photons, whose frequency and propagation direction differ from the driving laser pulses, thus providing various means to achieve an excellent signal to background separation. Based on the theoretical concept of vacuum emission, we employ an efficient numerical algorithm which allows us to model the collision of focused high-intensity laser pulses in unprecedented detail. We provide accurate predictions for the numbers of signal photons accessible in experiment. Our study is the first to predict the precise angular spread of the signal photons, and paves the way for a first verification of quantum vacuum nonlinearity in a well-controlled laboratory experiment at one of the many high-intensity laser facilities currently coming online.

  9. X-ray nanoprobe project at Taiwan Photon Source

    Energy Technology Data Exchange (ETDEWEB)

    Yin, Gung-Chian, E-mail: gcyin@nsrrc.org.tw; Chang, Shih-Hung; Chen, Bo-Yi; Chen, Huang-Yeh; Lin, Bi-Hsuan; Tseng, Shao-Chin; Lee, Chien-Yu; Wu, Jian-Xing; Tang, Mau-Tsu [National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan (China); Wu, Shao-Yun [National Tsing-Hua University, Hsinchu 30076, Taiwan (China)

    2016-07-27

    The hard X-ray nanoprobe facility at Taiwan Photon Source (TPS) provides versatile X-ray analysis techniques, with tens of nanometer resolution, including XRF, XAS, XEOL, projection microscope, CDI, etc. Resulting from the large numerical aperture obtained by utilizing Montel KB mirrors, the beamline with a moderate length 75 meters can conduct similar performance with those beamlines longer than 100 meters. The two silica-made Montel mirrors are 45 degree cut and placed in a V-shape to eliminate the gap loss and the deformation caused by gravity. The slope error of the KB mirror pair is less than 0.04 µrad accomplished by elastic emission machining (EEM) method. For the beamline, a horizontal DCM and two-stage focusing in horizontal direction is applied. For the endstation, a combination of SEM for quickly positioning the sample, a fly scanning system with laser interferometers, a precise temperature control system, and a load lock transfer system will be implemented. In this presentation, the design and construction progress of the beamline and endstation is reported. The endstation is scheduled to be in commissioning phase in 2016.

  10. Clinical applications of single photon emission tomography in neuromedicine. Part 1. Neuro-oncology, epilepsy, movement disorders, cerebrovascular disease

    International Nuclear Information System (INIS)

    Bartenstein, P.; Gruenwald, F.; Kuwert, T.; Tatsch, K.; Sabri, O.; Benkert, O.; Fahlbusch, R.; Gruender, G.; Herzholz, K.; Weiller, C.

    2000-01-01

    Single photon emission tomography is, because of its availability and the relatively low costs, the functional imaging modality currently most widely used for clinical applications in the brain. Beside the application of radiopharmaceuticals for the assessment of regional cerebral blood flow there is an increasing clinical use of more selective SPECT-radiopharmaceuticals, like amino acid analogs or receptor ligands. This article gives in its first part a critical review of the clinical applications of SPECT in neuro-oncology, epilepsy, basal ganglia disorders and cerebrovascular disease. (orig.) [de

  11. Photon and dilepton production across collision energies and centralities

    Energy Technology Data Exchange (ETDEWEB)

    Linnyk, Olena; Cassing, Wolfgang [Justus Liebig Universitaet Giessen (Germany); Bratkovskaya, Elena [Johann Wolfgang Goethe Universitaet, Frankfurt am Main (Germany); Frankfurt Institute for Advanced Studies, Frankfurt am Main (Germany)

    2014-07-01

    Real and virtual photons are established messengers of chiral symmetry restoration and deconfinement phase transition in heavy-ion collisions. We calculate the emission of photons and dileptons throughout the evolution of the heavy-ion collisions using the parton-hadron-string dynamics (PHSD) transport approach and interpret the recent observations of the strong photon elliptic flow at RHIC and LHC simultaneously with the precisely measured photon and dilepton spectra. This allows us to disentangle the individual hadronic and partonic emission sources and to conclude on the characteristics of the produced QCD matter - the temperatures, densities and the degree of thermalisation reached, the lifetime of the QGP and the modification of vector mesons. Comparing the known sources to the data, we examine the possibility to accommodate new effects, such as the photon production in the initial pre-equilibrium phase and the dilepton production in the mixed phase. Additionally, we provide predictions for the dilepton spectra at LHC, the collision centrality dependence of the photon yield at RHIC, and the excitation function of the low-mass dilepton yield, thus investigating the potential of the dilepton measurements within the RHIC beam energy scan program, FAIR and NICA facilities.

  12. Photon detector composed of metal and semiconductor nanoparticles

    International Nuclear Information System (INIS)

    Takahashi, Atsuo; Minoura, Norihiko; Karube, Isao

    2005-01-01

    Applying the function of the single electron transistor, a novel photon detector consisting of a self-assembled structure of metal and semiconductor nanoparticles and an organic insulating layer was developed. It showed coulomb blockade behavior under dark conditions and remarkable increase in current corresponding to light intensity under light irradiation. Ultraweak photon emission of about 600 counts per second in the ultraviolet region could be detected at room temperature by this photon counter

  13. Bio-Photons of Various Cellular Cultures and Tissues

    Science.gov (United States)

    Hann, Patrick; Knoesel, Ernst; Garzon, Maria; Lofland, Samuel; Pfieffer, Erik

    2008-04-01

    Since it is non-invasive, there has been increased research in the field of bio-optics. Many biological systems display an unusual phenomenon, delayed luminescence, produced by what is known as bio-photons. We present an apparatus and procedure for the detection of these ultra-weak photonic emissions using a single photon detection device. The results of bread yeast, saccramyces, and algae will be presented and compared to other reports in the literature.

  14. Air-Stable Surface-Passivated Perovskite Quantum Dots for Ultra-Robust, Single- and Two-Photon-Induced Amplified Spontaneous Emission

    KAUST Repository

    Pan, Jun

    2015-12-01

    We demonstrate ultra-air- and photostable CsPbBr3 quantum dots (QDs) by using an inorganic–organic hybrid ion pair as the capping ligand. This passivation approach to perovskite QDs yields high photoluminescence quantum yield with unprecedented operational stability in ambient conditions (60 ± 5% lab humidity) and high pump fluences, thus overcoming one of the greatest challenges impeding the development of perovskite-based applications. Due to the robustness of passivated perovskite QDs, we were able to induce ultrastable amplified spontaneous emission (ASE) in solution processed QD films not only through one photon but also through two-photon absorption processes. The latter has not been observed before in the family of perovskite materials. More importantly, passivated perovskite QD films showed remarkable photostability under continuous pulsed laser excitation in ambient conditions for at least 34 h (corresponds to 1.2 × 108 laser shots), substantially exceeding the stability of other colloidal QD systems in which ASE has been observed.

  15. Improvement of brain single photon emission tomography (SPET) using transmission data acquisition in a four-head SPET scanner

    International Nuclear Information System (INIS)

    Murase, Kenya; Tanada, Shuji; Inoue, Takeshi; Sugawara, Yoshifumi; Hamamoto, Ken

    1993-01-01

    Attenuation coefficient maps (μ-maps) are a useful way to compensate for non-uniform attenuation when performing single photon emission tomography (SPET). A new method was developed to record single photon transmission data and a μ-map for the brain was produced using a four-head SPET scanner. Transmission data were acquired by a gamma camera of opposite to a flood radioactive source attached to one of four gamma cameras in the four-head SPET scanner. Attenuation correction was performed using the iterative expectation maximization algorithm and the μ-map. Phantom studies demonstrated that this method could reconstruct the distribution of radioactivity more accurately than conventional methods, even for a severely non-uniform μ-map, and could improve the quality of SPET images. Clinical application to technetium-99m hexamethyl-propylene amine oxime (HMPAO) brain SPET also demonstrated the usefulness of this method. Thus, this method appears to be promising for improvement in the image quality and quantitative accuracy of brain SPET. (orig.)

  16. Spontaneous photon emission from a non-relativistic free charged particle in collapse models: A case study

    International Nuclear Information System (INIS)

    Bassi, A.; Donadi, S.

    2014-01-01

    We study the photon emission rate of a non-relativistic charged particle interacting with an external classical noise through its position. Both the particle and the electromagnetic field are quantized. Under only the dipole approximation, the equations of motion can be solved exactly for a free particle, or a particle bounded by an harmonic potential. The physical quantity we will be interested in is the spectrum of the radiation emitted by the particle, due to the interaction with the noise. We will highlight several properties of the spectrum and clarify some issues appearing in the literature, regarding the exact mathematical formula of a spectrum for a free particle.

  17. Optics of globular photonic crystals

    International Nuclear Information System (INIS)

    Gorelik, V S

    2007-01-01

    The results of experimental and theoretical studies of the optical properties of globular photonic crystals - new physical objects having a crystal structure with the lattice period exceeding considerably the atomic size, are presented. As globular photonic crystals, artificial opal matrices consisting of close-packed silica globules of diameter ∼200 nm were used. The reflection spectra of these objects characterising the parameters of photonic bands existing in these crystals in the visible spectral region are presented. The idealised models of the energy band structure of photonic crystals investigated in the review give analytic dispersion dependences for the group velocity and the effective photon mass in a globular photonic crystal. The characteristics of secondary emission excited in globular photonic crystals by monochromatic and broadband radiation are presented. The results of investigations of single-photon-excited delayed scattering of light observed in globular photonic crystals exposed to cw UV radiation and radiation from a repetitively pulsed copper vapour laser are presented. The possibilities of using globular photonic crystals as active media for lasing in different spectral regions are considered. It is proposed to use globular photonic crystals as sensitive sensors in optoelectronic devices for molecular analysis of organic and inorganic materials by the modern methods of laser spectroscopy. The results of experimental studies of spontaneous and stimulated globular scattering of light are discussed. The conditions for observing resonance and two-photon-excited delayed scattering of light are found. The possibility of accumulation and localisation of the laser radiation energy inside a globular photonic crystal is reported. (review)

  18. Emission computed tomography

    International Nuclear Information System (INIS)

    Ott, R.J.

    1986-01-01

    Emission Computed Tomography is a technique used for producing single or multiple cross-sectional images of the distribution of radionuclide labelled agents in vivo. The techniques of Single Photon Emission Computed Tomography (SPECT) and Positron Emission Tomography (PET) are described with particular regard to the function of the detectors used to produce images and the computer techniques used to build up images. (UK)

  19. Single-photon generator for optical telecommunication wavelength

    International Nuclear Information System (INIS)

    Usuki, T; Sakuma, Y; Hirose, S; Takemoto, K; Yokoyama, N; Miyazawa, T; Takatsu, M; Arakawa, Y

    2006-01-01

    We report on the generation of single-photon pulses from a single InAs/InP quantum dot in telecommunication bands (1.3-1.55 μm: higher transmittance through an optical fiber). First we prepared InAs quantum dots on InP (0 0 1) substrates in a low-pressure MOCVD by using a so-called InP 'double-cap' procedure. The quantum dots have well-controlled photo emission wavelength in the telecommunication bands. We also developed a single-photon emitter in which quantum dots were embedded. Numerical simulation designed the emitter to realize efficient injection of the emitted photons into a single-mode optical fiber. Using a Hanbury-Brown and Twiss technique has proved that the photons through the fiber were single photons

  20. Quantum interference of electrically generated single photons from a quantum dot.

    Science.gov (United States)

    Patel, Raj B; Bennett, Anthony J; Cooper, Ken; Atkinson, Paola; Nicoll, Christine A; Ritchie, David A; Shields, Andrew J

    2010-07-09

    Quantum interference lies at the foundation of many protocols for scalable quantum computing and communication with linear optics. To observe these effects the light source must emit photons that are indistinguishable. From a technological standpoint, it would be beneficial to have electrical control over the emission. Here we report of an electrically driven single-photon source emitting indistinguishable photons. The device consists of a layer of InAs quantum dots embedded in the intrinsic region of a p-i-n diode. Indistinguishability of consecutive photons is tested in a two-photon interference experiment under two modes of operation, continuous and pulsed current injection. We also present a complete theory based on the interference of photons with a Lorentzian spectrum which we compare to both our continuous wave and pulsed experiments. In the former case, a visibility was measured limited only by the timing resolution of our detection system. In the case of pulsed injection, we employ a two-pulse voltage sequence which suppresses multi-photon emission and allows us to carry out temporal filtering of photons which have undergone dephasing. The characteristic Hong-Ou-Mandel 'dip' is measured, resulting in a visibility of 64 +/- 4%.

  1. Coupled Photonic Crystal Cavity Array Laser

    DEFF Research Database (Denmark)

    Schubert, Martin

    in the quadratic lattice. Processing techniques are developed and optimized in order fabricate photonic crystals membranes in gallium arsenide with quantum dots as gain medium and in indium gallium arsenide phosphide with quantum wells as gain medium. Several key issues in process to ensure good quality....... The results are in good agreement with standard coupled mode theory. Also a novel type of photonic crystal structure is proposed called lambda shifted cavity which is a twodimensional photonic crystal laser analog of a VCSEL laser. Detailed measurements of the coupled modes in the photonic crystals...... with quantum dots are carried out. In agreement with a simple gain model the structures do not show stimulated emission. The spectral splitting due to the coupling between single cavities as well as arrays of cavities is studied theoretically and experimentally. Lasing is observed for photonic crystal cavity...

  2. The use of filtering methods to compensate for constant attenuation in single-photon emission computed tomography

    International Nuclear Information System (INIS)

    Gullberg, G.T.; Budinger, T.F.

    1981-01-01

    A back projection of filtered projection (BKFIL) reconstruction algorithm is presented that is applicable to single-photon emission computed tomography (ECT) in the presence of a constant attenuating medium such as the brain. The filters used in transmission computed tomography (TCT)-comprised of a ramp multiplied by window functions-are modified so that the single-photon ECT filter is a function of the constant attenuation coefficient. The filters give good reconstruction results with sufficient angular and lateral sampling. With continuous samples the BKFIL algorithm has a point spread function that is the Hankel transform of the window function. The resolution and statistical properties of the filters are demonstrated by various simulations which assume an ideal detector response. Statistical formulas for the reconstructed image show that the square of the percent-root-mean-square (percent-rms) uncertainty of the reconstruction is inversely proportional to the total measured counts. The results indicate that constant attenuation can be compensated for by using an attenuation-dependent filter that reconstructs the transverse section reliably. Computer time requirements are two times that of conventional TCT or positron ECT and there is no increase in memory requirements

  3. Photon-assisted tunneling in a Fe8 single-molecule magnet

    Science.gov (United States)

    Sorace, L.; Wernsdorfer, W.; Thirion, C.; Barra, A.-L.; Pacchioni, M.; Mailly, D.; Barbara, B.

    2003-12-01

    The low-temperature spin dynamics of a Fe8 single-molecule magnet was studied under circularly polarized electromagnetic radiation allowing us to establish clearly photon-assisted tunneling. This effect, while linear at low power, becomes highly nonlinear above a relatively low-power threshold. Heating due to phonon emission, spin-spin interactions, and coherent emission/absorption of photons might lead to the observed nonlinearity. These results are of importance if such systems are to be used as quantum computers.

  4. Stable single-photon source in the near infrared

    International Nuclear Information System (INIS)

    Gaebel, T; Popa, I; Gruber, A; Domhan, M; Jelezko, F; Wrachtrup, J

    2004-01-01

    Owing to their unsurpassed photostability, defects in solids may be ideal candidates for single-photon sources. Here we report on generation of single photons by optical excitation of a yet unexplored defect in diamond, the nickel-nitrogen complex (NE8) centre. The most striking feature of the defect is its emission bandwidth of 1.2 nm at room temperature. The emission wavelength of the defect is around 800 nm, which is suitable for telecom fibres. In addition, in this spectral region little background light from the diamond bulk material is detected. Consequently, a high contrast in antibunching measurements is achieved

  5. Occult primary tumors of the head and neck: accuracy of thallium 201 single-photon emission computed tomography and computed tomography and/or magnetic resonance imaging

    NARCIS (Netherlands)

    van Veen, S. A.; Balm, A. J.; Valdés Olmos, R. A.; Hoefnagel, C. A.; Hilgers, F. J.; Tan, I. B.; Pameijer, F. A.

    2001-01-01

    To determine the accuracy of thallium 201 single-photon emission computed tomography (thallium SPECT) and computed tomography and/or magnetic resonance imaging (CT/MRI) in the detection of occult primary tumors of the head and neck. Study of diagnostic tests. National Cancer Institute, Amsterdam,

  6. Multimodal microscopy and the stepwise multi-photon activation fluorescence of melanin

    Science.gov (United States)

    Lai, Zhenhua

    The author's work is divided into three aspects: multimodal microscopy, stepwise multi-photon activation fluorescence (SMPAF) of melanin, and customized-profile lenses (CPL) for on-axis laser scanners, which will be introduced respectively. A multimodal microscope provides the ability to image samples with multiple modalities on the same stage, which incorporates the benefits of all modalities. The multimodal microscopes developed in this dissertation are the Keck 3D fusion multimodal microscope 2.0 (3DFM 2.0), upgraded from the old 3DFM with improved performance and flexibility, and the multimodal microscope for targeting small particles (the "Target" system). The control systems developed for both microscopes are low-cost and easy-to-build, with all components off-the-shelf. The control system have not only significantly decreased the complexity and size of the microscope, but also increased the pixel resolution and flexibility. The SMPAF of melanin, activated by a continuous-wave (CW) mode near-infrared (NIR) laser, has potential applications for a low-cost and reliable method of detecting melanin. The photophysics of melanin SMPAF has been studied by theoretical analysis of the excitation process and investigation of the spectra, activation threshold, and photon number absorption of melanin SMPAF. SMPAF images of melanin in mouse hair and skin, mouse melanoma, and human black and white hairs are compared with images taken by conventional multi-photon fluorescence microscopy (MPFM) and confocal reflectance microscopy (CRM). SMPAF images significantly increase specificity and demonstrate the potential to increase sensitivity for melanin detection compared to MPFM images and CRM images. Employing melanin SMPAF imaging to detect melanin inside human skin in vivo has been demonstrated, which proves the effectiveness of melanin detection using SMPAF for medical purposes. Selective melanin ablation with micrometer resolution has been presented using the Target system

  7. High energy photons production in nuclear reactions

    International Nuclear Information System (INIS)

    Nifenecker, H.; Pinston, J.A.

    1990-01-01

    Hard photon production, in nucleus-nucleus collisions, were studied at beam energies between 10 and 125 MeV. The main characteristics of the photon emission are deduced. They suggest that the neutron-proton collisions in the early stage of the reaction are the main source of high energy gamma-rays. An overview of the theoretical approaches is given and compared with experimental results. Theoretical attempts to include the contribution of charged pion exchange currents to photon production, in calculations of proton-nucleus-gamma and nucleus-nucleus-gamma reactions, showed suitable fitting with experimental data

  8. Photonic band gap materials: design, synthesis, and applications

    International Nuclear Information System (INIS)

    John, S.

    2000-01-01

    Full text: Unlike semiconductors which facilitate the coherent propagation of electrons, photonic band gap (PBG) materials execute their novel functions through the coherent localization of photons. I review and discuss our recent synthesis of a large scale three-dimensional silicon photonic crystal with a complete photonic band gap near 1.5 microns. When a PBG material is doped with impurity atoms which have an electronic transition that lies within the gap, spontaneous emission of light from the atom is inhibited. Inside the gap, the photon forms a bound state to the atom. Outside the gap, radiative dynamics in the colored vacuum is highly non Markovian. I discuss the influence of these memory effects on laser action. When spontaneous emission is absent, the next order radiative effect (resonance dipole dipole interaction between atoms) must be incorporated leading to anomalous nonlinear optical effects which occur at a much lower threshold than in ordinary vacuum. I describe the collective switching of two-level atoms near a photonic band edge, by external laser field, from a passive state to one exhibiting population inversion. This effect is forbidden in ordinary vacuum. However, in the context of a PBG material, this effect may be utilized for an all-optical transistor. Finally, I discuss the prospects for a phase sensitive, single atom quantum memory device, onto which information may be written by an external laser pulse

  9. Realisation of a ultra-high vacuum system and technique development of microscopical emitters preparation in silicium. First measurements of field emission current and field photoemission

    International Nuclear Information System (INIS)

    El Manouni, A.

    1990-12-01

    The development of research in the domain of photocathode (electron sources) illuminated by laser light to produce intense multiple bunches of electrons in short time is needed by many applications as linear collider e + e - , free electron laser, lasertron, etc... In this way, after a study of field emission, of photoemission and of photofield emission, we prepared microscopical emitters in silicium heavy and weakly doped a boron using a technique of microlithography. Then, we realized a system of ultra-high vacuum of studying property of emission from photocathodes realized. The experiment results obtained in field emission and photofield emission have shown that a behaviour unexpected for P-silicium tips array compared to P + -silicon tips array. With P-type silicon, a quantum yield of 21 percent has been measured for laser power of 140 mW and for applied field of 1.125 x 10 7 V/m and an instantaneous response to laser light beam has been observed. It has been noted that presence of oxyde at the surface of photocathode limits extensively the emission current. The fluctuations of emission current are due to quality of vacuum [fr

  10. High-quality asynchronous heralded single-photon source at telecom wavelength

    International Nuclear Information System (INIS)

    Fasel, Sylvain; Alibart, Olivier; Tanzilli, Sebastien; Baldi, Pascal; Beveratos, Alexios; Gisin, Nicolas; Zbinden, Hugo

    2004-01-01

    We report on the experimental realization and characterization of an asynchronous heralded single-photon source based on spontaneous parametric down-conversion. Photons at 1550 nm are heralded as being inside a single-mode fibre with more than 60% probability, and the multi-photon emission probability is reduced by a factor of up to more than 500 compared to Poissonian light sources. These figures of merit, together with the choice of telecom wavelength for the heralded photons, are compatible with practical applications needing very efficient and robust single-photon sources

  11. Role of bone photonic densitometry in uremic osteodystrophy

    International Nuclear Information System (INIS)

    Specchi Bighi, E.; Baldelli, S.; Argalia, G.

    1987-01-01

    The aim of this investigation is to evaluate the role of bone photonic densitometry in uremic osteodystrophy. Bone mineral contenent (BMC) and bone density (BD) have been measured in 80 hemodialyzed patients by double photonic emission densitometry. Photonic densitometry shows an higher sensibility to quantitative changes in bone mineral contenent than metacarpal index (IM). Photonic densitometry is unable to differentiate osteoporosis from osteomalacia; this differential diagnosis can be obtained by radiological analysis: low BD and low IM means osteoporosis, low BD and resorptive changes in cortical bone means osteomalacia and/or hyperparathyroidism. Photonic densitometry is particulary suitable for uremic osteodystrophy follow-up because of its easy ripetibility and innocuousness and for its close correlation with iPTH variations

  12. Diagnostic accuracy of single photon emission CT in Alzheimer-type dementia

    International Nuclear Information System (INIS)

    Hanyu, Haruki; Abe, Shinei; Arai, Hisayuki; Asano, Tetsuichi; Iwamoto, Toshihiko; Takasaki, Masaru; Suzuki, Takanari

    1992-01-01

    To determine the diagnostic accuracy of single photon emission computed tomography (SPECT) with 123 I-IMP in Alzheimer-type dementia (ATD), we studied 46 ATD patients and 23 healthy controls. The patients fulfilled the NINCDS-ADRDA criteria for probable or definite ATD and were classified as having mild, moderate, and severe ATD by neuropsychological examinations. To assess regional cerebral blood flow, we performed qualitative SPECT image analysis without any knowledge of the subject's clinical classification. The image was regarded as abnormal if cerebral blood flow was reduced in the unlilateral or bilateral temporoparietal association areas, with or without any reduction of flow in other brain regions. The diagnostic sensitivity (abnormal image/ patient) of 123 I-IMP SPECT in mild, moderate and severe ATD was 67%, 86% and 92%, because an abnormal image was found in only 2/23 healthy controls. Eight ATD patients without reduced temporoparietal perfusion showed normal perfusion or frontal hypoperfusion. These results suggest that 123 I-IMP SPECT may provide an accurate and sensitive diagnostic marker for ATD. The detection of these characteristic abnormalities of cerebral perfusion could well be applied to the clinical diagnosis of ATD. (author)

  13. Diagnostic accuracy of single photon emission CT in Alzheimer-type dementia

    Energy Technology Data Exchange (ETDEWEB)

    Hanyu, Haruki; Abe, Shinei; Arai, Hisayuki; Asano, Tetsuichi; Iwamoto, Toshihiko; Takasaki, Masaru; Suzuki, Takanari [Tokyo Medical Coll. (Japan)

    1992-06-01

    To determine the diagnostic accuracy of single photon emission computed tomography (SPECT) with [sup 123]I-IMP in Alzheimer-type dementia (ATD), we studied 46 ATD patients and 23 healthy controls. The patients fulfilled the NINCDS-ADRDA criteria for probable or definite ATD and were classified as having mild, moderate, and severe ATD by neuropsychological examinations. To assess regional cerebral blood flow, we performed qualitative SPECT image analysis without any knowledge of the subject's clinical classification. The image was regarded as abnormal if cerebral blood flow was reduced in the unlilateral or bilateral temporoparietal association areas, with or without any reduction of flow in other brain regions. The diagnostic sensitivity (abnormal image/ patient) of [sup 123]I-IMP SPECT in mild, moderate and severe ATD was 67%, 86% and 92%, because an abnormal image was found in only 2/23 healthy controls. Eight ATD patients without reduced temporoparietal perfusion showed normal perfusion or frontal hypoperfusion. These results suggest that [sup 123]I-IMP SPECT may provide an accurate and sensitive diagnostic marker for ATD. The detection of these characteristic abnormalities of cerebral perfusion could well be applied to the clinical diagnosis of ATD. (author).

  14. Resting state rCBF mapping with single-photon emission tomography and positron emission tomography: magnitude and origin of differences

    Energy Technology Data Exchange (ETDEWEB)

    Jonsson, C.; Kimiaei, S.; Larsson, S.A. [Section of Nuclear Medicine, Department of Hospital Physics, Karolinska Hospital and Department of Medical Radiation Physics, Stockholm University, Stockholm (Sweden); Pagani, M. [Institute of Experimental Medicine, CNR, Rome (Italy); Ingvar, M. [Section of Cognitive Neurophysiology, Karolinska Hospital, Stockholm (Sweden); Thurfjell, L. [Center of Image Analysis, Uppsala University, Uppsala (Sweden); Jacobsson, H. [Department of Diagnostic Radiology, Karolinska Hospital, Stockholm (Sweden)

    1998-02-01

    Single-photon emission tomography (SPET), using technetium-99m hexamethylpropylene amine oxime, and positron emission tomography (PET), using oxygen-15 butanol were compared in six healthy male volunteers with regard to the mapping of resting state regional cerebral blood flow (rCBF). A computerized brain atlas was utilized for 3D regional analyses and comparison of 64 selected and normalized volumes of interest (VOIs). The normalized mean rCBF values in SPET, as compared to PET, were higher in most of the Brodmann areas in the frontal and parietal lobes (4.8% and 8.7% respectively). The average differences were small in the temporal (2.3%) and occipital (1.1%) lobes. PET values were clearly higher in small VOIs like the thalamus (12.3%), hippocampus (12.3%) and basal ganglia (9.9%). A resolution phantom study showed that the in-plane SPET/PET system resolution was 11.0/7.5 mm. In conclusion, SPET and PET data demonstrated a fairly good agreement despite the superior spatial resolution of PET. The differences between SPET and PET rCBF are mainly due to physiological and physical factors, the data processing, normalization and co-registration methods. In order to further improve mapping of rCBF with SPET it is imperative not only to improve the spatial resolution but also to apply accurate correction techniques for scatter, attenuation and non-linear extraction. (orig.) With 6 figs., 3 tabs., 23 refs.

  15. Apertureless near-field/far-field CW two-photon microscope for biological and material imaging and spectroscopic applications.

    Science.gov (United States)

    Nowak, Derek B; Lawrence, A J; Sánchez, Erik J

    2010-12-10

    We present the development of a versatile spectroscopic imaging tool to allow for imaging with single-molecule sensitivity and high spatial resolution. The microscope allows for near-field and subdiffraction-limited far-field imaging by integrating a shear-force microscope on top of a custom inverted microscope design. The instrument has the ability to image in ambient conditions with optical resolutions on the order of tens of nanometers in the near field. A single low-cost computer controls the microscope with a field programmable gate array data acquisition card. High spatial resolution imaging is achieved with an inexpensive CW multiphoton excitation source, using an apertureless probe and simplified optical pathways. The high-resolution, combined with high collection efficiency and single-molecule sensitive optical capabilities of the microscope, are demonstrated with a low-cost CW laser source as well as a mode-locked laser source.

  16. Quantum optics with quantum dots in photonic nanowires

    DEFF Research Database (Denmark)

    Claudon, Julien; Munsch, Matthieu; Bleuse, Joel

    2012-01-01

    Besides microcavities and photonic crystals, photonic nanowires have recently emerged as a novel resource for solidstate quantum optics. We will review recent studies which demonstrate an excellent control over the spontaneous emission of InAs quantum dots (QDs) embedded in single-mode Ga...... quantum optoelectronic devices. Quite amazingly, this approach has for instance permitted (unlike microcavity-based approaches) to combine for the first time a record-high efficiency (72%) and a negligible g(2) in a QD single photon source....

  17. Soft photons in the Lund model

    International Nuclear Information System (INIS)

    Andersson, B.; Dahlqvist, P.; Gustafson, G.

    1988-03-01

    We investigate the emission of real and virtual photons with small transverse momenta close to zero cms rapidity in proton-proton collisions. We consider a model, built upon the space time structure of the Lund string fragmentation model combined with the Fritiof model for hadronic interactions. The model contains a gauge and Lorentz invariant, albeit semiclassical, treatment of the currents from the final state hadrons as well as their valence constituents. We further investigate the effects of resonance decay, increase of the transverse momentum width of the string fluxtube, gluon emission leading to 'bent' strings and finally also the occurrence of polarization charges (virtual qq-production) along the string world sheet. We show that the spectrum for real and virtual (e + e - pairs) photon emission always will be within a factor of 2 to 3 from the long wave length limit (the Low limit) for transverse momenta up to a few hundred MeV/c. We conclude that if the present experimental indications for a much larger source of emission should be confirmed, then a major revision will be necessary in our present understanding of the space time structure and/or the energy densities available in hadron fragmentation. (authors)

  18. Very Efficient Single-Photon Sources Based on Quantum Dots in Photonic Wires

    DEFF Research Database (Denmark)

    Gerard, Jean-Michel; Claudon, Julien; Bleuse, Joel

    2014-01-01

    . By placing a tip-shaped or trumpet-like tapering at the output end of the wire, a highly directional Gaussian far-field emission pattern is obtained. More generally, a photonic wire containing a quantum dot appears as an attractive template to explore and exploit in a solid-state system the unique optical...

  19. Improved diagnostic performance of exercise thallium-201 single photon emission computed tomography over planar imaging in the diagnosis of coronary artery disease: a receiver operating characteristic analysis

    International Nuclear Information System (INIS)

    Fintel, D.J.; Links, J.M.; Brinker, J.A.; Frank, T.L.; Parker, M.; Becker, L.C.

    1989-01-01

    Qualitative interpretation of tomographic and planar scintigrams, a five point rating scale and receiver operating characteristic analysis were utilized to compare single photon emission computed tomography and conventional planar imaging of myocardial thallium-201 uptake in the accuracy of the diagnosis of coronary artery disease and individual vessel involvement. One hundred twelve patients undergoing cardiac catheterization and 23 normal volunteers performed symptom-limited treadmill exercise, followed by stress and redistribution imaging by both tomographic and planar techniques, with the order determined randomly. Paired receiver operating characteristic curves revealed that single photon emission computed tomography was more accurate than planar imaging over the entire range of decision thresholds for the overall detection and exclusion of coronary artery disease and involvement of the left anterior descending and left circumflex coronary arteries. Tomography offered relatively greater advantages in male patients and in patients with milder forms of coronary artery disease, who had no prior myocardial infarction, only single vessel involvement or no lesion greater than or equal to 50 to 69%. Tomography did not appear to provide improved diagnosis in women or in detection of disease in the right coronary artery. Although overall detection of coronary artery disease was not improved in patients with prior myocardial infarction, tomography provided improved identification of normal and abnormal vascular regions. These results indicate that single photon emission computed tomography provides improved diagnostic performance compared with planar imaging in many clinical subgroups

  20. Mapping microscopic order in plant and mammalian cells and tissues: novel differential polarization attachment for new generation confocal microscopes (DP-LSM)

    Science.gov (United States)

    Steinbach, G.; Pawlak, K.; Pomozi, I.; Tóth, E. A.; Molnár, A.; Matkó, J.; Garab, G.

    2014-03-01

    Elucidation of the molecular architecture of complex, highly organized molecular macro-assemblies is an important, basic task for biology. Differential polarization (DP) measurements, such as linear (LD) and circular dichroism (CD) or the anisotropy of the fluorescence emission (r), which can be carried out in a dichrograph or spectrofluorimeter, respectively, carry unique, spatially averaged information about the molecular organization of the sample. For inhomogeneous samples—e.g. cells and tissues—measurements on macroscopic scale are not satisfactory, and in some cases not feasible, thus microscopic techniques must be applied. The microscopic DP-imaging technique, when based on confocal laser scanning microscope (LSM), allows the pixel by pixel mapping of anisotropy of a sample in 2D and 3D. The first DP-LSM configuration, which, in fluorescence mode, allowed confocal imaging of different DP quantities in real-time, without interfering with the ‘conventional’ imaging, was built on a Zeiss LSM410. It was demonstrated to be capable of determining non-confocally the linear birefringence (LB) or LD of a sample and, confocally, its FDLD (fluorescence detected LD), the degree of polarization (P) and the anisotropy of the fluorescence emission (r), following polarized and non-polarized excitation, respectively (Steinbach et al 2009 Acta Histochem.111 316-25). This DP-LSM configuration, however, cannot simply be adopted to new generation microscopes with considerably more compact structures. As shown here, for an Olympus FV500, we designed an easy-to-install DP attachment to determine LB, LD, FDLD and r, in new-generation confocal microscopes, which, in principle, can be complemented with a P-imaging unit, but specifically to the brand and type of LSM.