The Experts below are selected from a list of 180351 Experts worldwide ranked by ideXlab platform
Geoffrey A. Ozin - One of the best experts on this subject based on the ideXlab platform.
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Tungsten inverse opals: the influence of absorption on the photonic band structure in the visible Spectral Region
Conference on Lasers and Electro-Optics International Quantum Electronics Conference and Photonic Applications Systems Technologies, 2004Co-Authors: G. Von Freymann, Sajeev John, M. Schulz-dobrick, E. Vekris, Nicolas Tétreault, Sean Wong, Vladimir Kitaev, Geoffrey A. OzinAbstract:We fabricate and characterize tungsten inverse opals for the visible and near-infrared Spectral Region. The influence of absorption in this Spectral Region and the resulting breakdown of the bandstructure are experimentally investigated in detail
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Tungsten inverse opals: The influence of absorption on the photonic band structure in the visible Spectral Region
Applied Physics Letters, 2004Co-Authors: G. Von Freymann, Sajeev John, M. Schulz-dobrick, E. Vekris, Nicolas Tétreault, Sean Wong, Vladimir Kitaev, Geoffrey A. OzinAbstract:We report on the fabrication and characterization of tungsten inverse opals for the visible and near-infrared Spectral Region. The crucial influence of the strong absorption in this Spectral Region is experimentally investigated by means of a gradient deposition technique and characterization with reflectance and transmittance spectroscopy. With increasing metal infiltration, we observe the breakdown of the photonic band structure, resulting first in a sphere-cavity-like behavior and finally in a behavior similar to that of a periodically structured metal surface.
Giuseppe Tondello - One of the best experts on this subject based on the ideXlab platform.
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Quantum efficiency measurement on a CCD detector in the 0.3- to 1100-nm Spectral Region
EUV X-Ray and Gamma-Ray Instrumentation for Astronomy VIII, 1997Co-Authors: Luca Poletto, Leonardo Placentino, Alessio Boscolo, Maria Guglielmina Pelizzo, Giuseppe TondelloAbstract:The performances of a CCD have been evaluated in a very wide Spectral Region, which comprises near IR, visible, near and far UV, EUV and soft x-ray Spectral Regions. The CCD detector is a back illuminated one, 512 by 512 format, 24 by 24 micrometer squared pixel. The performed measurements consist mainly on the determination of the quantum efficiency in the 0.3 - 1100 nm (4.5 keV - 1 eV) Spectral Region. Three different experimental setup have been used: a Czerny-Turner monochromator for the 1100 - 250 nm Region, a Johnson-Onaka monochromator for the 250 - 30 nm Region, and a grazing incidence Rowland monochromator for the 25 - 0.3 nm Region. The tested CCD exhibits high values of quantum efficiency in the analyzed Spectral range, representing a very useful detector of radiation in the extended optical domain.
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Performances of a CCD camera from 1- to 1100-nm Spectral Region
Sensors Sensor Systems and Sensor Data Processing, 1997Co-Authors: Luca Poletto, Leonardo Placentino, Alessio Boscolo, Maria Guglielmina Pelizzo, Giuseppe TondelloAbstract:The performances of a CCD have been evaluated in a very wide Spectral Region, which comprises the near IR, the visible, the near and far UV, EUV and soft x-ray Spectral Regions. The CCD detector is a back illuminated one, 512 X 512 format, 24 X 24 micrometers 2 pixel. The measurements performed consist mainly on the determination of the quantum efficiency and of the uniformity of response in the 1 - 1100 nm Spectral Region. Three different experimental setup have been used for the various Spectral range: a Czerny-Turner monochromator for the 1100 - 250 nm Region, a Johnson-Onaka monochromator for the 250 - 30 nm Region, and a grazing incidence monochromator for the 30 - 1 nm Region. The tested CCD exhibits high values of quantum efficiency and a good uniformity of response in the analyzed Spectral range.© (1997) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
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Performances of metachrome II as a scintillator for the far and vacuum ultraviolet Spectral Region
Optical Engineering, 1996Co-Authors: Leonardo Placentino, Giampiero Naletto, Emanuele Pace, Giuseppe TondelloAbstract:A couple of metachrome II samples having different thicknesses are tested as the downconverter fluorescent layer in the far and vacuum UV (58 to 297 nm). Their performance is compared with that obtained by tetraphenyl butadiene, another scintillator widely used in this Spectral Region. The emission angular distribution, the fluorescent spectrum, and the absolute conversion efficiencies are measured for all of the phosphors. The results show some peculiar effects related to the incident angle with the surface where the phosphors are deposited; moreover, they show that tetraphenyl butadiene offers higher efficiency than metachrome II, but also that the latter shows good efficiency throughout the investigated Spectral Region. This fact indicates that interesting applications can be performed with metachrome II when it is used as the downconverter phosphor with silicon detectors whose Spectral response matches well the emission spectrum of metachrome II. For example, this could enable having CCDs sensitive in the extreme UV Region, without requiring very expensive and sophisticated UV-sensitive treatments.
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Fluorescence of metachrome in the far- and vacuum-ultraviolet Spectral Region
X-Ray and Ultraviolet Sensors and Applications, 1995Co-Authors: Giampiero Naletto, Emanuele Pace, Leonardo Placentino, Giuseppe TondelloAbstract:Some measurements have been performed in order to fully characterize metachrome as down- converter fluorescent layer in the far and vacuum ultraviolet, from 46 up to 254 nm. In particular, a couple of samples having different thickness provided by Photometrics Inc. have been tested and their performances have been compared with the ones obtained by tetraphenyl butadiene (TPB), another scintillator widely used in this Spectral Region. The emission angular distribution, the fluorescent spectrum and the absolute conversion efficiencies have been measured for all the phosphors. The results show that TPB offers higher efficiency than metachrome, but also that the latter is well efficient in all the investigated Spectral Region. This is interesting in the case of using this phosphor as down-converter with silicon detectors, so permitting for example to have CCD sensitive also in the extreme ultraviolet Region.
G. Von Freymann - One of the best experts on this subject based on the ideXlab platform.
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Tungsten inverse opals: the influence of absorption on the photonic band structure in the visible Spectral Region
Conference on Lasers and Electro-Optics International Quantum Electronics Conference and Photonic Applications Systems Technologies, 2004Co-Authors: G. Von Freymann, Sajeev John, M. Schulz-dobrick, E. Vekris, Nicolas Tétreault, Sean Wong, Vladimir Kitaev, Geoffrey A. OzinAbstract:We fabricate and characterize tungsten inverse opals for the visible and near-infrared Spectral Region. The influence of absorption in this Spectral Region and the resulting breakdown of the bandstructure are experimentally investigated in detail
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Tungsten inverse opals: The influence of absorption on the photonic band structure in the visible Spectral Region
Applied Physics Letters, 2004Co-Authors: G. Von Freymann, Sajeev John, M. Schulz-dobrick, E. Vekris, Nicolas Tétreault, Sean Wong, Vladimir Kitaev, Geoffrey A. OzinAbstract:We report on the fabrication and characterization of tungsten inverse opals for the visible and near-infrared Spectral Region. The crucial influence of the strong absorption in this Spectral Region is experimentally investigated by means of a gradient deposition technique and characterization with reflectance and transmittance spectroscopy. With increasing metal infiltration, we observe the breakdown of the photonic band structure, resulting first in a sphere-cavity-like behavior and finally in a behavior similar to that of a periodically structured metal surface.
Leonardo Placentino - One of the best experts on this subject based on the ideXlab platform.
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Quantum efficiency measurement on a CCD detector in the 0.3- to 1100-nm Spectral Region
EUV X-Ray and Gamma-Ray Instrumentation for Astronomy VIII, 1997Co-Authors: Luca Poletto, Leonardo Placentino, Alessio Boscolo, Maria Guglielmina Pelizzo, Giuseppe TondelloAbstract:The performances of a CCD have been evaluated in a very wide Spectral Region, which comprises near IR, visible, near and far UV, EUV and soft x-ray Spectral Regions. The CCD detector is a back illuminated one, 512 by 512 format, 24 by 24 micrometer squared pixel. The performed measurements consist mainly on the determination of the quantum efficiency in the 0.3 - 1100 nm (4.5 keV - 1 eV) Spectral Region. Three different experimental setup have been used: a Czerny-Turner monochromator for the 1100 - 250 nm Region, a Johnson-Onaka monochromator for the 250 - 30 nm Region, and a grazing incidence Rowland monochromator for the 25 - 0.3 nm Region. The tested CCD exhibits high values of quantum efficiency in the analyzed Spectral range, representing a very useful detector of radiation in the extended optical domain.
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Performances of a CCD camera from 1- to 1100-nm Spectral Region
Sensors Sensor Systems and Sensor Data Processing, 1997Co-Authors: Luca Poletto, Leonardo Placentino, Alessio Boscolo, Maria Guglielmina Pelizzo, Giuseppe TondelloAbstract:The performances of a CCD have been evaluated in a very wide Spectral Region, which comprises the near IR, the visible, the near and far UV, EUV and soft x-ray Spectral Regions. The CCD detector is a back illuminated one, 512 X 512 format, 24 X 24 micrometers 2 pixel. The measurements performed consist mainly on the determination of the quantum efficiency and of the uniformity of response in the 1 - 1100 nm Spectral Region. Three different experimental setup have been used for the various Spectral range: a Czerny-Turner monochromator for the 1100 - 250 nm Region, a Johnson-Onaka monochromator for the 250 - 30 nm Region, and a grazing incidence monochromator for the 30 - 1 nm Region. The tested CCD exhibits high values of quantum efficiency and a good uniformity of response in the analyzed Spectral range.© (1997) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
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Performances of metachrome II as a scintillator for the far and vacuum ultraviolet Spectral Region
Optical Engineering, 1996Co-Authors: Leonardo Placentino, Giampiero Naletto, Emanuele Pace, Giuseppe TondelloAbstract:A couple of metachrome II samples having different thicknesses are tested as the downconverter fluorescent layer in the far and vacuum UV (58 to 297 nm). Their performance is compared with that obtained by tetraphenyl butadiene, another scintillator widely used in this Spectral Region. The emission angular distribution, the fluorescent spectrum, and the absolute conversion efficiencies are measured for all of the phosphors. The results show some peculiar effects related to the incident angle with the surface where the phosphors are deposited; moreover, they show that tetraphenyl butadiene offers higher efficiency than metachrome II, but also that the latter shows good efficiency throughout the investigated Spectral Region. This fact indicates that interesting applications can be performed with metachrome II when it is used as the downconverter phosphor with silicon detectors whose Spectral response matches well the emission spectrum of metachrome II. For example, this could enable having CCDs sensitive in the extreme UV Region, without requiring very expensive and sophisticated UV-sensitive treatments.
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Fluorescence of metachrome in the far- and vacuum-ultraviolet Spectral Region
X-Ray and Ultraviolet Sensors and Applications, 1995Co-Authors: Giampiero Naletto, Emanuele Pace, Leonardo Placentino, Giuseppe TondelloAbstract:Some measurements have been performed in order to fully characterize metachrome as down- converter fluorescent layer in the far and vacuum ultraviolet, from 46 up to 254 nm. In particular, a couple of samples having different thickness provided by Photometrics Inc. have been tested and their performances have been compared with the ones obtained by tetraphenyl butadiene (TPB), another scintillator widely used in this Spectral Region. The emission angular distribution, the fluorescent spectrum and the absolute conversion efficiencies have been measured for all the phosphors. The results show that TPB offers higher efficiency than metachrome, but also that the latter is well efficient in all the investigated Spectral Region. This is interesting in the case of using this phosphor as down-converter with silicon detectors, so permitting for example to have CCD sensitive also in the extreme ultraviolet Region.
R. H. Tipping - One of the best experts on this subject based on the ideXlab platform.
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Water vapor continuum in the millimeter Spectral Region
AIP Conference Proceedings, 2008Co-Authors: R. H. TippingAbstract:A theory is presented for the calculation of the continuous absorption of water molecules in the millimeter Spectral Region. Using only the known rotational constants, dipole moment, and reasonable values of two Lennard‐Jones potential parameters, both the absolute magnitude and temperature dependence of the absorption coefficient are in agreement with empirical results.
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Water vapor continuum in the millimeter Spectral Region
Journal of Chemical Physics, 1990Co-Authors: R. H. TippingAbstract:A theory is presented for the calculation of the continuous absorption of water molecules in the millimeter Spectral Region. The theory is based on a generalization of Fano’s theory in which the Spectral density, the Fourier transform of the dipole‐moment correlation function, is calculated for a system consisting of a pair of molecules. The internal states are written in terms of the line space of the system, and the resolvent operator is obtained using the well‐known Lanczos algorithm. For the interaction between two water molecules, we include only the leading dipole–dipole term of the long‐range anisotropic potential, and model the isotropic interaction, used to calculate the statistical weight within the quasi‐static approximation, by a Lennard–Jones potential. Using reasonable values for the two Lennard–Jones potential parameters, and the known rotational constants and permanent dipole moment of a water molecule, we calculate the absorption coefficient for frequencies up to 450 GHz for temperatures between 282 and 315 K. The present results are in good agreement with an empirical model for the water continuum based on combined laboratory and atmospheric measurements. We conclude from our results that, contrary to some previous assertions, the strong negative temperature dependence as well as the magnitude of the continuum absorption, at least for the millimeter Spectral Region, can be explained in terms of the far‐wings of allowed rotational transitions.
