Giorgio Turri - Academia.edu (original) (raw)
Papers by Giorgio Turri
Physical Review Letters, 2001
An experimental K-shell photodetachment study of Li 2 giving rise to doubly photoionized Li 1 ion... more An experimental K-shell photodetachment study of Li 2 giving rise to doubly photoionized Li 1 ions has been carried out at the Advanced Light Source, using a collinear photon-ion beam apparatus. The experiment reveals dramatic structure, differing substantially both qualitatively and quantitatively from the corresponding processes above the 1s ionization threshold in Li and Li 1 , as predicted by our enhanced R-matrix calculation. The experimental/theoretical comparison shows good agreement over some of the photon energy range, and also reveals some puzzling discrepancies.
APS Division of Atomic, Molecular and Optical Physics Meeting Abstracts, 2020
The photodouble ionization of the water molecule is studied at 20 eV excess energy in a combined ... more The photodouble ionization of the water molecule is studied at 20 eV excess energy in a combined experimental and theoretical investigation. In the experiments, two photoelectrons of equal kinetic energy are detected in coincidence after energy and angular selection. On the theoretical side, a generalized Sturmian function approach is implemented to describe accurately the correlated two-electron continuum, while separable products of Moccia orbitals [J. Chem. Phys. 40, 2164 (1964)] are used for the initial electronic state of the water molecule. The theoretical triple-differential cross sections (TDCSs) are averaged over all possible molecular orientations in order to be compared with the experiments. The measured TDCSs display rich angular distributions that are in large part well reproduced by the adopted first-order treatment of the interaction with a two-active-electron target.
Physical Review A, 2020
The photodouble ionization of the water molecule is studied at 20 eV excess energy in a combined ... more The photodouble ionization of the water molecule is studied at 20 eV excess energy in a combined experimental and theoretical investigation. In the experiments, two photoelectrons of equal kinetic energy are detected in coincidence after energy and angular selection. On the theoretical side, a generalized Sturmian function approach is implemented to describe accurately the correlated two-electron continuum, while separable products of Moccia orbitals [J. Chem. Phys. 40, 2164 (1964)] are used for the initial electronic state of the water molecule. The theoretical triple-differential cross sections (TDCSs) are averaged over all possible molecular orientations in order to be compared with the experiments. The measured TDCSs display rich angular distributions that are in large part well reproduced by the adopted first-order treatment of the interaction with a two-active-electron target.
Radiation Physics and Chemistry, 2004
We have investigated with unprecedented levels of detail photodetachment of negative ions and pho... more We have investigated with unprecedented levels of detail photodetachment of negative ions and photoionization of molecules using the brightness, spectral resolution, and tunability of the Advanced Light Source at Lawrence Berkeley National Laboratory. In particular, we report here on investigations carried out in K-shell photodetachment of atomic Li− and He−. We also report on angular distribution of core-level iodine 4d photoelectrons from the HI molecule. In both cases comparison with calculations is discussed.
Physical Review Letters, 2004
Angle-and spin-resolved photoelectron spectroscopy with linearly and circularly polarized synchro... more Angle-and spin-resolved photoelectron spectroscopy with linearly and circularly polarized synchrotron radiation were used to study the electronic structure of model triatomic molecules, hydrogen sulfide, and carbonyl sulfide. The spin-polarization measurements of the molecular field split components of the S 2p photolines revealed a strong effect of the different molecular environments. The validity of simple atomic models to explain the results is discussed.
Journal of Electron Spectroscopy and Related Phenomena, 2005
We have investigated with unprecedented levels of detail K-shell photodetachment of metastable 1s... more We have investigated with unprecedented levels of detail K-shell photodetachment of metastable 1s2s2p 4 P He − using a merged photon-ion beam apparatus. Our recent investigation allowed the first absolute cross-section measurement of the 2s2p 2 4 P Feshbach resonance by way of a resonant simultaneous double Auger decay of unprecedented strength. In addition, higher resolution absolute cross-section measurements of triply excited resonances giving rise to hollow He − ion allowed a more stringent comparison with four different calculations.
The 45-year-monitoring of optical and mechanical properties of the various semiconductor crystals... more The 45-year-monitoring of optical and mechanical properties of the various semiconductor crystals grown in the sixties of the past century shows that the stimuli for long-term improvement of crystal quality prevail over those which lead to its degradation. Evolution of optical and mechanical properties testifies that now in diamond-like gallium phosphide (GaP) doped with nitrogen (N), the impurity is a regular element of the new crystal lattice-it increases the forbidden gap, and at relevant concentration and level of optical excitation creates a bound excitonic crystal. The ternary compound CdIn 2 S 4 , now having the perfect normal (instead of partly inversed) spinel crystal lattice, as well as GaP with evenly distributed impurities, demonstrate new stable and bright luminescent phenomena, including stimulated emission and "hot" luminescence at room temperature. All chosen semiconductor crystals from different groups of semiconductor compounds demonstrate the longterm ordering and improvement of useful for application properties. Existing technologies help us to reproduce artificially these naturally ordered structures for application in optoelectronics.
In this paper we present a part of our investigation of the photodouble ionization (PDI) of gaseo... more In this paper we present a part of our investigation of the photodouble ionization (PDI) of gaseous water. Synchrotron radiation from ELETTRA storage ring was used to ionize the water molecule, and the two emitted electrons were collected in coincidence after angle and energy selection. We have compared the measured dication states with those known from literature and showed the angular distributions of the two photoelectrons measured for the first time, for different excess energies and under different energy sharing conditions. A detailed comparison with theoretical calculations is given to help understand some details of the PDI mechanism.Fil: Penson, Conner. Embry-riddle Aeronautical University; Estados UnidosFil: Turri, Giorgio. Full Sail University; Estados UnidosFil: Avaldi, Lorenzo. Consiglio Nazionale delle Ricerche; ItaliaFil: Randazzo, Juan Martin. Comisión Nacional de Energía Atómica. Gerencia del Area Investigación y Aplicaciones No Nucleares. Gerencia de Física (Centr...
EQEC '05. European Quantum Electronics Conference, 2005., 2005
ABSTRACT The relaxation of optically induced anisotropy in azulene has been studied by polarisati... more ABSTRACT The relaxation of optically induced anisotropy in azulene has been studied by polarisation sensitive time resolved experiment. The pump pulse by electronically exciting selects a class of molecular orientation and the probe photoionizes it.
In this paper we present a part of our investigation of the photodouble ionization (PDI) of gaseo... more In this paper we present a part of our investigation of the photodouble ionization (PDI) of gaseous water. Synchrotron radiation from ELETTRA storage ring was used to ionize the water molecule, and the two emitted electrons were collected in coincidence after angle and energy selection. We have compared the measured dication states with those known from literature and showed the angular distributions of the two photoelectrons measured for the first time, for different excess energies and under different energy sharing conditions. A detailed comparison with theoretical calculations is given to help understand some details of the PDI mechanism
On the left is the binding energy spectrum of the water dication comparison between the reference... more On the left is the binding energy spectrum of the water dication comparison between the reference measurements done by Eland [1] (in red) and our measurements (in black). Our results follow the trend of increasing in the number of coincidence yield until around 41 eV but do not seem to follow the trend after about 45 eV of decreasing until the binding energy hits about 48 eV. Gas Phase Beamline
OPTICAL ENGINEERING, 2007
Epitaxial single-crystal chemical-vapor-deposited diamond with ͑100͒ crystal orientation is obtai... more Epitaxial single-crystal chemical-vapor-deposited diamond with ͑100͒ crystal orientation is obtained from Element Six ͑Ascot, United Kingdom͒ and Apollo Diamond ͑Boston, Massachusetts͒. Both companies supply 5 ϫ 5-mm squares with thicknesses of 0.35 to 1.74 mm. Element Six also provides disks with a state of the art diameter of 10 to 11 mm and a thickness of 1.0 mm. The absorption coefficient measured by laser calorimetry at 1.064 m is 0.003 cm −1 for squares from Element Six and 0.07 cm −1 for squares from Apollo. One Apollo specimen has an absorption coefficient near those of the Element Six material. Absorption coefficients of Element Six disks are 0.008 to 0.03 cm −1. Each square specimen can be rotated between orientations that produce minimum or maximum loss of polarization of a 1.064-m laser beam transmitted through the diamond. Minimum loss is in the range 0 to 11% ͑mean =5%͒ and maximum loss is 8 to 27% ͑mean= 17% ͒. Element Six disks produce a loss of polarization in the range 0 to 4%, depending on the angle of rotation of the disk. Part of the 0.04 to 0.6% total integrated optical scatter in the forward hemisphere at 1.064 m can be attributed to surface roughness.
The goal of this experiment was to measure coincident 2-electron emissions from water molecules w... more The goal of this experiment was to measure coincident 2-electron emissions from water molecules with unequal energies to analyze the direct emission processes of H20. The ELETTRA Synchrotron was utilized for its highly tunable photon selection and its coincidence measurement capabilities. A photon flux of specific energy was fired into a thin stream of water vapor in near-perfect vacuum and electron detectors at known angles in the plane of emission were scanned through different energy and emission angles. The detectors only recorded a measurement if it was in coincidence with the measurement of another detector to ensure that all measurements, were a cause of photo-double ionization. The motivation of this experiment was a lack of documentation in the field of photon double ionization of water with unequal energy sharing due to the complexity of the H20 molecule. The data gathered will, ultimately, lead to a better understanding of the structure of the water molecule, of the photo...
We measure the photoionization cross-section of vibrationally excited levels in the S2 state of a... more We measure the photoionization cross-section of vibrationally excited levels in the S2 state of azulene by femtosecond pump-probe spectroscopy. At the wavelengths studied (349-265 nm in the pump) the transient signals exhibit two distinct and welldefined behaviours: (i) Short-term (on the order of a picosecond) polarization dependent transients and (ii) longer (10 ps – 1 ns) time-scale decays. This letter focuses on the short time transient. In contrast to an earlier study by Diau et al.(1) we unambiguously assign the fast initial decay signal to rotational dephasing of the initial alignment created by the hal-00289272, version 1- 20 Jun 2008 pump transition.
ABSTRACT Previous core-photodetachment studies of He^- showed a strong discrepancy with accepted ... more ABSTRACT Previous core-photodetachment studies of He^- showed a strong discrepancy with accepted theory [1], attracting considerable additional theoretical interest. These new theoretical studies include ab initio calculations of triply-excited quartet states and the 2s2p^2 ^4P state of He^-, located just below the 1s threshold [2,3]. Measured positions, widths, and strengths of these resonances provide a sensitive test for these new calculations. We will present recent high-resolution measurements of the suspected triply-excited He^- resonances, as well as measurements of the absolute double-detachment cross sections in He^- obtained at the ALS. In addition, the He^- 2s2p^2 ^4P resonant state was observed to decay to the He^+ 1s ground state. This represents the first evidence of a simultaneous 3-electron decay process in a core-excited negative ion. [1] Berrah et al., Phys. Rev. Lett. 88, 093001 (2002). [2] Sanz-Vicario et al., Phys. Rev. A 66, 052713 (2002). [3] Zatsarinny et al., J. Phys. B 35, 4161 (2002).
Spectroscopic properties of neodymium-doped yttrium lithium fluoride were measured at different t... more Spectroscopic properties of neodymium-doped yttrium lithium fluoride were measured at different temperatures from 35 K to 350 K in specimens with 1 at% Nd3+ concentration. The absorption spectrum was measured at room temperature from 400 to 900 nm. The decay dynamics of the 4F3/2 multiplet was investigated by measuring the fluorescence lifetime as a function of the sample temperature, and the radiative decay time was derived by extrapolation to 0 K. The stimulated-emission cross-sections of the transitions from the 4F3/2 to the 4I9/2, 4I11/2, and 4I13/2 levels were obtained from the fluorescence spectrum measured at different temperatures, using the Aull–Jenssen technique. The results show consistency with most results previously published at room temperature, extending them over a broader range of temperatures. A semi-empirical formula for the magnitude of the stimulated-emission cross-section as a function of temperature in the 250 K to 350 K temperature range, is presented for th...
Journal of Physics B: Atomic, Molecular and Optical Physics, 2007
![Research paper thumbnail of Influence of modifier oxides on the structural and optical properties of binary TeO[sub 2] glasses](https://attachments.academia-assets.com/76507058/thumbnails/1.jpg)
](Journal of Applied Physics, 2007
Five different glass compositions with equal TeO 2 molar concentration and various intermediate c... more Five different glass compositions with equal TeO 2 molar concentration and various intermediate constituents were prepared to examine the influence of such intermediate species on the tellurite network. A correlation between the glasses' structural network and optical properties is presented. Peak Raman gain coefficients, on the order of 40 times the gain of SiO 2 , are reported in this paper.
Europium doped alkaline earth fluoride [Eu:AEF 2 (AE = Ca, Sr, Ba)] nanoparticles were synthesize... more Europium doped alkaline earth fluoride [Eu:AEF 2 (AE = Ca, Sr, Ba)] nanoparticles were synthesized and systematically incorporated into the core of modified chemical vapor deposition (MCVD)-derived silicabased preforms by solution doping. The resulting preforms were examined to determine the impact of the nanoparticles chemistry on the spectroscopic behavior of the glass. The dominant existence of Eu 3+ was demonstrated in all preforms, which is in contrast to conventional solution doped preforms employing dissolved europium salts where Eu 2+ is primarily observed. Raman spectroscopy and fluorescence lifetime measurements indicated that the nanoparticles composition is effective in controlling, at a local chemical and structural level, the spectroscopic properties of active dopants in optical fiber glasses. Further, there is a systematic and marked increase in radiative lifetime, τ, of the Eu 3+ emission that follows the cationic mass; τ Ca < τ Sr < τ Ba with the BaF 2-derived sample yielding a 37% lengthening of the lifetime over the CaF 2-derived one. Such nanoscale control of what otherwise is silica glass could be useful for realizing property-enhanced and tailored spectroscopic performance from otherwise "standard" materials, e.g., vaporderived silica, in next generation optical fibers.
Physical Review Letters, 2001
An experimental K-shell photodetachment study of Li 2 giving rise to doubly photoionized Li 1 ion... more An experimental K-shell photodetachment study of Li 2 giving rise to doubly photoionized Li 1 ions has been carried out at the Advanced Light Source, using a collinear photon-ion beam apparatus. The experiment reveals dramatic structure, differing substantially both qualitatively and quantitatively from the corresponding processes above the 1s ionization threshold in Li and Li 1 , as predicted by our enhanced R-matrix calculation. The experimental/theoretical comparison shows good agreement over some of the photon energy range, and also reveals some puzzling discrepancies.
APS Division of Atomic, Molecular and Optical Physics Meeting Abstracts, 2020
The photodouble ionization of the water molecule is studied at 20 eV excess energy in a combined ... more The photodouble ionization of the water molecule is studied at 20 eV excess energy in a combined experimental and theoretical investigation. In the experiments, two photoelectrons of equal kinetic energy are detected in coincidence after energy and angular selection. On the theoretical side, a generalized Sturmian function approach is implemented to describe accurately the correlated two-electron continuum, while separable products of Moccia orbitals [J. Chem. Phys. 40, 2164 (1964)] are used for the initial electronic state of the water molecule. The theoretical triple-differential cross sections (TDCSs) are averaged over all possible molecular orientations in order to be compared with the experiments. The measured TDCSs display rich angular distributions that are in large part well reproduced by the adopted first-order treatment of the interaction with a two-active-electron target.
Physical Review A, 2020
The photodouble ionization of the water molecule is studied at 20 eV excess energy in a combined ... more The photodouble ionization of the water molecule is studied at 20 eV excess energy in a combined experimental and theoretical investigation. In the experiments, two photoelectrons of equal kinetic energy are detected in coincidence after energy and angular selection. On the theoretical side, a generalized Sturmian function approach is implemented to describe accurately the correlated two-electron continuum, while separable products of Moccia orbitals [J. Chem. Phys. 40, 2164 (1964)] are used for the initial electronic state of the water molecule. The theoretical triple-differential cross sections (TDCSs) are averaged over all possible molecular orientations in order to be compared with the experiments. The measured TDCSs display rich angular distributions that are in large part well reproduced by the adopted first-order treatment of the interaction with a two-active-electron target.
Radiation Physics and Chemistry, 2004
We have investigated with unprecedented levels of detail photodetachment of negative ions and pho... more We have investigated with unprecedented levels of detail photodetachment of negative ions and photoionization of molecules using the brightness, spectral resolution, and tunability of the Advanced Light Source at Lawrence Berkeley National Laboratory. In particular, we report here on investigations carried out in K-shell photodetachment of atomic Li− and He−. We also report on angular distribution of core-level iodine 4d photoelectrons from the HI molecule. In both cases comparison with calculations is discussed.
Physical Review Letters, 2004
Angle-and spin-resolved photoelectron spectroscopy with linearly and circularly polarized synchro... more Angle-and spin-resolved photoelectron spectroscopy with linearly and circularly polarized synchrotron radiation were used to study the electronic structure of model triatomic molecules, hydrogen sulfide, and carbonyl sulfide. The spin-polarization measurements of the molecular field split components of the S 2p photolines revealed a strong effect of the different molecular environments. The validity of simple atomic models to explain the results is discussed.
Journal of Electron Spectroscopy and Related Phenomena, 2005
We have investigated with unprecedented levels of detail K-shell photodetachment of metastable 1s... more We have investigated with unprecedented levels of detail K-shell photodetachment of metastable 1s2s2p 4 P He − using a merged photon-ion beam apparatus. Our recent investigation allowed the first absolute cross-section measurement of the 2s2p 2 4 P Feshbach resonance by way of a resonant simultaneous double Auger decay of unprecedented strength. In addition, higher resolution absolute cross-section measurements of triply excited resonances giving rise to hollow He − ion allowed a more stringent comparison with four different calculations.
The 45-year-monitoring of optical and mechanical properties of the various semiconductor crystals... more The 45-year-monitoring of optical and mechanical properties of the various semiconductor crystals grown in the sixties of the past century shows that the stimuli for long-term improvement of crystal quality prevail over those which lead to its degradation. Evolution of optical and mechanical properties testifies that now in diamond-like gallium phosphide (GaP) doped with nitrogen (N), the impurity is a regular element of the new crystal lattice-it increases the forbidden gap, and at relevant concentration and level of optical excitation creates a bound excitonic crystal. The ternary compound CdIn 2 S 4 , now having the perfect normal (instead of partly inversed) spinel crystal lattice, as well as GaP with evenly distributed impurities, demonstrate new stable and bright luminescent phenomena, including stimulated emission and "hot" luminescence at room temperature. All chosen semiconductor crystals from different groups of semiconductor compounds demonstrate the longterm ordering and improvement of useful for application properties. Existing technologies help us to reproduce artificially these naturally ordered structures for application in optoelectronics.
In this paper we present a part of our investigation of the photodouble ionization (PDI) of gaseo... more In this paper we present a part of our investigation of the photodouble ionization (PDI) of gaseous water. Synchrotron radiation from ELETTRA storage ring was used to ionize the water molecule, and the two emitted electrons were collected in coincidence after angle and energy selection. We have compared the measured dication states with those known from literature and showed the angular distributions of the two photoelectrons measured for the first time, for different excess energies and under different energy sharing conditions. A detailed comparison with theoretical calculations is given to help understand some details of the PDI mechanism.Fil: Penson, Conner. Embry-riddle Aeronautical University; Estados UnidosFil: Turri, Giorgio. Full Sail University; Estados UnidosFil: Avaldi, Lorenzo. Consiglio Nazionale delle Ricerche; ItaliaFil: Randazzo, Juan Martin. Comisión Nacional de Energía Atómica. Gerencia del Area Investigación y Aplicaciones No Nucleares. Gerencia de Física (Centr...
EQEC '05. European Quantum Electronics Conference, 2005., 2005
ABSTRACT The relaxation of optically induced anisotropy in azulene has been studied by polarisati... more ABSTRACT The relaxation of optically induced anisotropy in azulene has been studied by polarisation sensitive time resolved experiment. The pump pulse by electronically exciting selects a class of molecular orientation and the probe photoionizes it.
In this paper we present a part of our investigation of the photodouble ionization (PDI) of gaseo... more In this paper we present a part of our investigation of the photodouble ionization (PDI) of gaseous water. Synchrotron radiation from ELETTRA storage ring was used to ionize the water molecule, and the two emitted electrons were collected in coincidence after angle and energy selection. We have compared the measured dication states with those known from literature and showed the angular distributions of the two photoelectrons measured for the first time, for different excess energies and under different energy sharing conditions. A detailed comparison with theoretical calculations is given to help understand some details of the PDI mechanism
On the left is the binding energy spectrum of the water dication comparison between the reference... more On the left is the binding energy spectrum of the water dication comparison between the reference measurements done by Eland [1] (in red) and our measurements (in black). Our results follow the trend of increasing in the number of coincidence yield until around 41 eV but do not seem to follow the trend after about 45 eV of decreasing until the binding energy hits about 48 eV. Gas Phase Beamline
OPTICAL ENGINEERING, 2007
Epitaxial single-crystal chemical-vapor-deposited diamond with ͑100͒ crystal orientation is obtai... more Epitaxial single-crystal chemical-vapor-deposited diamond with ͑100͒ crystal orientation is obtained from Element Six ͑Ascot, United Kingdom͒ and Apollo Diamond ͑Boston, Massachusetts͒. Both companies supply 5 ϫ 5-mm squares with thicknesses of 0.35 to 1.74 mm. Element Six also provides disks with a state of the art diameter of 10 to 11 mm and a thickness of 1.0 mm. The absorption coefficient measured by laser calorimetry at 1.064 m is 0.003 cm −1 for squares from Element Six and 0.07 cm −1 for squares from Apollo. One Apollo specimen has an absorption coefficient near those of the Element Six material. Absorption coefficients of Element Six disks are 0.008 to 0.03 cm −1. Each square specimen can be rotated between orientations that produce minimum or maximum loss of polarization of a 1.064-m laser beam transmitted through the diamond. Minimum loss is in the range 0 to 11% ͑mean =5%͒ and maximum loss is 8 to 27% ͑mean= 17% ͒. Element Six disks produce a loss of polarization in the range 0 to 4%, depending on the angle of rotation of the disk. Part of the 0.04 to 0.6% total integrated optical scatter in the forward hemisphere at 1.064 m can be attributed to surface roughness.
The goal of this experiment was to measure coincident 2-electron emissions from water molecules w... more The goal of this experiment was to measure coincident 2-electron emissions from water molecules with unequal energies to analyze the direct emission processes of H20. The ELETTRA Synchrotron was utilized for its highly tunable photon selection and its coincidence measurement capabilities. A photon flux of specific energy was fired into a thin stream of water vapor in near-perfect vacuum and electron detectors at known angles in the plane of emission were scanned through different energy and emission angles. The detectors only recorded a measurement if it was in coincidence with the measurement of another detector to ensure that all measurements, were a cause of photo-double ionization. The motivation of this experiment was a lack of documentation in the field of photon double ionization of water with unequal energy sharing due to the complexity of the H20 molecule. The data gathered will, ultimately, lead to a better understanding of the structure of the water molecule, of the photo...
We measure the photoionization cross-section of vibrationally excited levels in the S2 state of a... more We measure the photoionization cross-section of vibrationally excited levels in the S2 state of azulene by femtosecond pump-probe spectroscopy. At the wavelengths studied (349-265 nm in the pump) the transient signals exhibit two distinct and welldefined behaviours: (i) Short-term (on the order of a picosecond) polarization dependent transients and (ii) longer (10 ps – 1 ns) time-scale decays. This letter focuses on the short time transient. In contrast to an earlier study by Diau et al.(1) we unambiguously assign the fast initial decay signal to rotational dephasing of the initial alignment created by the hal-00289272, version 1- 20 Jun 2008 pump transition.
ABSTRACT Previous core-photodetachment studies of He^- showed a strong discrepancy with accepted ... more ABSTRACT Previous core-photodetachment studies of He^- showed a strong discrepancy with accepted theory [1], attracting considerable additional theoretical interest. These new theoretical studies include ab initio calculations of triply-excited quartet states and the 2s2p^2 ^4P state of He^-, located just below the 1s threshold [2,3]. Measured positions, widths, and strengths of these resonances provide a sensitive test for these new calculations. We will present recent high-resolution measurements of the suspected triply-excited He^- resonances, as well as measurements of the absolute double-detachment cross sections in He^- obtained at the ALS. In addition, the He^- 2s2p^2 ^4P resonant state was observed to decay to the He^+ 1s ground state. This represents the first evidence of a simultaneous 3-electron decay process in a core-excited negative ion. [1] Berrah et al., Phys. Rev. Lett. 88, 093001 (2002). [2] Sanz-Vicario et al., Phys. Rev. A 66, 052713 (2002). [3] Zatsarinny et al., J. Phys. B 35, 4161 (2002).
Spectroscopic properties of neodymium-doped yttrium lithium fluoride were measured at different t... more Spectroscopic properties of neodymium-doped yttrium lithium fluoride were measured at different temperatures from 35 K to 350 K in specimens with 1 at% Nd3+ concentration. The absorption spectrum was measured at room temperature from 400 to 900 nm. The decay dynamics of the 4F3/2 multiplet was investigated by measuring the fluorescence lifetime as a function of the sample temperature, and the radiative decay time was derived by extrapolation to 0 K. The stimulated-emission cross-sections of the transitions from the 4F3/2 to the 4I9/2, 4I11/2, and 4I13/2 levels were obtained from the fluorescence spectrum measured at different temperatures, using the Aull–Jenssen technique. The results show consistency with most results previously published at room temperature, extending them over a broader range of temperatures. A semi-empirical formula for the magnitude of the stimulated-emission cross-section as a function of temperature in the 250 K to 350 K temperature range, is presented for th...
Journal of Physics B: Atomic, Molecular and Optical Physics, 2007
Journal of Applied Physics, 2007
Five different glass compositions with equal TeO 2 molar concentration and various intermediate c... more Five different glass compositions with equal TeO 2 molar concentration and various intermediate constituents were prepared to examine the influence of such intermediate species on the tellurite network. A correlation between the glasses' structural network and optical properties is presented. Peak Raman gain coefficients, on the order of 40 times the gain of SiO 2 , are reported in this paper.
Europium doped alkaline earth fluoride [Eu:AEF 2 (AE = Ca, Sr, Ba)] nanoparticles were synthesize... more Europium doped alkaline earth fluoride [Eu:AEF 2 (AE = Ca, Sr, Ba)] nanoparticles were synthesized and systematically incorporated into the core of modified chemical vapor deposition (MCVD)-derived silicabased preforms by solution doping. The resulting preforms were examined to determine the impact of the nanoparticles chemistry on the spectroscopic behavior of the glass. The dominant existence of Eu 3+ was demonstrated in all preforms, which is in contrast to conventional solution doped preforms employing dissolved europium salts where Eu 2+ is primarily observed. Raman spectroscopy and fluorescence lifetime measurements indicated that the nanoparticles composition is effective in controlling, at a local chemical and structural level, the spectroscopic properties of active dopants in optical fiber glasses. Further, there is a systematic and marked increase in radiative lifetime, τ, of the Eu 3+ emission that follows the cationic mass; τ Ca < τ Sr < τ Ba with the BaF 2-derived sample yielding a 37% lengthening of the lifetime over the CaF 2-derived one. Such nanoscale control of what otherwise is silica glass could be useful for realizing property-enhanced and tailored spectroscopic performance from otherwise "standard" materials, e.g., vaporderived silica, in next generation optical fibers.