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1. Evidence for two-electron processes in the mutual neutralization of O- with O+ and N+ at Subthermal Collision Energies

Author

de Ruette, N., Dochain, A., Launoy, T., Nascimento, R. F., Kaminska, M., Stockett, M. H., Vaeck, N., Schmidt, H. T., Cederquist, H., and Urbain, X.

Subjects
Physics - Atomic Physics
Abstract

We have measured total absolute cross sections for the Mutual Neutralization (MN) of O- with O+/N+. A fine resolution (of about 50 meV) in the kinetic energy spectra of the product neutral atoms allows unique identification of the atomic states participating in the mutual neutralization process. Cross sections and branching ratios have also been calculated down to 1 meV center-of-mass collision energy for these two systems with a multi-channel Landau-Zener model and an asymptotic method for the ionic-covalent coupling matrix elements. The importance of two-electron processes in one-electron transfer is demonstrated by the dominant contribution of a core-excited configuration of the nitrogen atom in N+ + O- collisions. This effect is partially accounted for by introducing configuration mixing in the evaluation of coupling matrix elements., Comment: 5 pages, 4 figures

Published
2018
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2. Spontaneous decay of small copper cluster anions Cu$_n^-$, $n=3-6$ on long time scales

Author

Hansen, K., Stockett, M. H., Kaminska, M., Nascimento, R. F., Anderson, E. K., Gatchell, M., Chartkunchand, K. C., Eklund, G., Zettergren, H., Schmidt, H. T., and Cederquist, H.

Subjects
Physics - Atomic and Molecular Clusters
Abstract

We have measured the spontaneous neutral particle emission from copper cluster anions (Cu$_n^-$, $n=3-6$) stored at cryogenic temperatures in one of the electrostatic ion storage rings of the DESIREE (Double ElectroStatic Ion Ring ExpEriment) facility at Stockholm University. The measured rate of emission from the stored Cu$_3^-$ ions follows a single power law decay for about 1 ms but then decreases much more rapidly with time. The latter behavior may be due to a decrease in the density of available final states in Cu$_3$ as the excitation energies of the decaying ions approach the electron detachment threshold. The emissions from Cu$_4^-$, Cu$_5^-$ and Cu$_6^-$ are well-described by sums of two power laws that are quenched by radiative cooling of the stored ions with characteristic times between a few and hundreds of milliseconds. We relate these two-component behaviors to populations of stored ions with higher and lower angular momenta. In a separate experiment, we studied the laser-induced decay of Cu$_6^-$ ions that were excited by 1.13 eV or 1.45 eV photons after 46 milliseconds of storage.

Published
2018
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3. Radiative lifetimes of the bound excited states of $\text{Pt}^{-}$

Author

Chartkunchand, K. C., Kamińska, M., Anderson, E. K., Kristiansson, M. K., Eklund, G., Hole, O. M., Nascimento, R. F., Blom, M., Björkhage, M., Källberg, A., Löfgren, P., Reinhed, P., Rosén, S., Simonsson, A., Thomas, R. D., Mannervik, S., Davis, V. T., Neill, P. A., Thompson, J. S., Hanstorp, D., Zettergren, H., Cederquist, H., and Schmidt, H. T.

Subjects
Physics - Atomic Physics
Abstract

The intrinsic radiative lifetimes of the $5d^{10}6s$ $^{2}\text{S}_{1/2}$ and $5d^{9}6s^{2}$ $^{2}\text{D}_{3/2}$ bound excited states in the platinum anion $\text{Pt}^{-}$ have been studied at cryogenic temperatures at the Double ElectroStatic Ion Ring Experiment (DESIREE) facility at Stockholm University. The intrinsic lifetime of the higher-lying $5d^{10}6s$ $^{2}\text{S}_{1/2}$ state was measurement to be 2.54$\pm$0.10 s, while only a lifetime in the range of 50 - 200 ms could be estimated for the $5d^{9}6s^{2}$ $^{2}\text{D}_{3/2}$ fine-structure level. The storage lifetime of the $\text{Pt}^{-}$ ion beam was measured to be a little over 15 minutes at a ring temperature of 13 K. The present study reports the lifetime of an atomic negative ion in an excited bound state with an electron configuration different from that of the ground state., Comment: 6 pages, 5 figures

Published
2018
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4. The lifetime of the bound excited level in Ni$^-$

Author

Kamińska, M., Davis, V. T., Hole, O. M., Nascimento, R. F., Chartakunchand, K. C., Blom, M., Björkhage, M., Källberg, A., Löfgren, P., Reinhed, P., Rosén, S., Simonsson, A., Thomas, R. D., Mannervik, S., Neill, P. A., Thompson, J. S., Schmidt, H. T., Cederquist, H., and Hanstorp, D.

Subjects
Physics - Atomic Physics
Abstract

The intrinsic lifetime of the upper level in the bound-bound 3d$^9$4s$^2$ $^2$D$_{3/2}$ $\rightarrow$ 3d$^9$4s$^2$ $^2$D$_{5/2}$ radiative transition in Ni$^-$ was measured to be 15.1 $\pm$ 0.4 s. The experiment was performed at cryogenic temperatures in one of the ion-beam storage rings of the DESIREE (Double ElectroStatic Ion Ring Experiment) facility at Stockholm University. The storage lifetime of the Ni$^-$ ion-beam was measured to be close to five minutes at a ring temperature of 13 K., Comment: 12 pages, 5 figures

Published
2015
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5. Experimental evidence of twin fast metastable H(2S) atoms from dissociation of cold H_2 induced by electrons

Author

Robert, J., Zappa, F., Carvalho, C. R., Jalbert, Ginette, Nascimento, R. F., Trimeche, A., Dulieu, O., Medina, Aline, Carvalho, Carla, and Faria, N. V. de Castro

Subjects
Physics - Atomic Physics
Abstract

We report the direct detection of two metastable H(2S) atoms coming from the dissociation of a single cold H_2 molecule, in coincidence measurements. The molecular dissociation was induced by electron impact in order to avoid limitations by the selection rules governing radiative transitions. Two detectors, placed close from the collision center, measure the neutral metastable H(2S) through a localized quenching process, which mixes the H(2S) state with the H(2P), leading to a Lyman-\alpha detection. Our data show the accomplishment of a coincidence measurement which proves for the first time the existence of the H(2S)-H(2S) dissociation channel., Comment: 5 pages, 5 figures

Published
2013
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6. Evaluation of headspace solid-phase microextraction gas chromatography - mass spectrometry for the characterization of volatile organic compounds from melon (Cucumis melo L.) flowers

Author

SILVA, F. A. N., SILVA, A. A., FERNANDES, N. S., RODRIGUES, T. H. S., CANUTO, K. M., NASCIMENTO, R. F., BRITO, E. S. de, ARAGAO, F. A. S. de, FREITAS, B. M., ZOCOLO, G. J., Francisca Aliny Nunes Silva, Embrapa Agoindústria Tropical, bolsista, Nayanny de Sousa Fernandes, UFC - Universidade Federal do Ceará, Tigressa Helena Soares Rodrigues, UVA - Universidade Estadual Vale do Acaraú, KIRLEY MARQUES CANUTO, CNPAT, Ronaldo Ferreira do Nascimento, UFC - Universidade Federal do Ceará, EDY SOUSA DE BRITO, CNPAT, FERNANDO ANTONIO SOUZA DE ARAGAO, CNPAT, Breno Magalhães Freitas, UFC - Universidade Federal do Ceará, GUILHERME JULIAO ZOCOLO, CNPAT., and Alexander Alves da Silva, UNESP - Universidade Estadual Paulista

Subjects
SPME, Melons, VOCs, Flor de melão, GC-MS, Melão, Headspace
Abstract

Made available in DSpace on 2018-12-03T23:33:37Z (GMT). No. of bitstreams: 1 ART18077.pdf: 964998 bytes, checksum: a6946ccf3cc6df000bbe50fe506d440d (MD5) Previous issue date: 2018-11-16

Published
2018

7. Organophosphorus Pesticide in Sapodilla (Manilkara zapota) Fruit

Author

ALCANTARA, D. B., PAZ, M. S. O., RODRIGUES, T. H. S., FERNANDES, T. S. M., BARBOSA, P. G. A., LOIOLA, A. R., GRINBERG, P., ZOCOLO, G. J., BRITO, E. S. de, NASCIMENTO, R. F. do, Daniel B. Alcântara, Universidade Federal do Ceará, Departamento de Química Analítica e Fisico-Química, Mario S. O. Paz, Universidade Federal do Ceará, Departamento de Química Analítica e Fisico-Química, Tigressa H. S. Rodrigues, Universidade Estadual Vale do Acaraú, Departamento de Química, Tatiana S. M. Fernandes, Universidade Federal do Ceará, Departamento de Engenharia Hidráulica e Ambiental, Pablo G. A. Barbosa, Universidade Federal do Ceará, Departamento de Química Analítica e Fisico-Química, Adonay R. Loiola, Universidade Federal do Ceará, Departamento de Química Orgânica e Inorgânica, Patricia Grinberg, National Research Council Canada, GUILHERME JULIAO ZOCOLO, CNPAT, EDY SOUSA DE BRITO, CNPAT, and Ronaldo F. do Nascimento, Universidade Federal do Ceará, Departamento de Química Analítica e Fisico-Química.

Subjects
Efeito matriz, Validação, GC-MS, Quechers
Abstract

Made available in DSpace on 2019-01-11T23:36:43Z (GMT). No. of bitstreams: 1 ART18107.pdf: 2333800 bytes, checksum: 952f464546d27bc13e33d21154bf8872 (MD5) Previous issue date: 2019-01-08

Published
2018

8. Improvement of pea protein isolate powder properties by agglomeration in a fluidized bed: comparison between binder solutions

Author

Nascimento, R. F., Andreola, K, Rosa, J. G., Taranto, Osvaldir, Nascimento, R. F., Andreola, K, Rosa, J. G., and Taranto, Osvaldir

Abstract

[EN] This study aimed to compare the agglomeration process of pea protein isolate (PPI) using water and aqueous gum Arabic solution as binder liquids. Drying air temperature and binder flow rate were set at 75 °C and 3.1 mL/min, respectively. Moisture content, mean particle size, wetting time and flowability were analyzed. Using water as binder liquid, the responses were (4.0 ± 0.4)%, 316.13 ± 16.73 μm, 10 s and free flow, respectively. Aqueous gum Arabic solution provided (2.9 ± 0.5)%, 462.67 ± 51.23 μm, 3 s and free flow as responses. Gum Arabic solution showed to be a more promising binder.

Published
2018

9. Influence of drying conditions on the acacia gum particle growth in fluidized bed agglomeration: in-line monitoring of particle size

Author

Rosa, Juliana, Nascimento, R. F., Andreola, K., Taranto, O. P., Rosa, Juliana, Nascimento, R. F., Andreola, K., and Taranto, O. P.

Abstract

[EN] Acacia gum is an important food emulsifier that presents poor instant properties which can be improved by fluidized bed agglomeration. This study investigated the influence of drying conditions on particle growth kinetics using an in-line particle size monitoring by spatial filter velocimetry. The drying conditions varied according to the binder flow rate and the fluidizing air temperature. The particle growth kinectis showed drying conditions dependence. At mild drying conditions the growth rate and the process yield were higher. The in-line particle size monitoring was useful to observe the influence of the drying conditions on the growth kinetics.

Published
2018

11. Lifetimes of bound excited states of Pt−

Author

Chartkunchand, KC, primary, Kamińska, M., additional, Anderson, E. K., additional, Kristiansson, M. K., additional, Eklund, G., additional, Hole, O. M., additional, Nascimento, R. F., additional, Blom, M., additional, Björkhage, M., additional, Källberg, A., additional, Löfgren, P., additional, Reinhed, P., additional, Rosén, S., additional, Simonsson, A., additional, Thomas, R. D., additional, Mannervik, S., additional, Davis, V. T., additional, Neill, P. A., additional, Thompson, J. S., additional, Hanstorp, D., additional, Zettergren, H., additional, Cederquist, H., additional, and Schmidt, H. T., additional

Published
2017
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13. Physical Review Letters

Author

Robert, J., Zappa, F., Carvalho, C. R. de, Jalbert, Ginette, Nascimento, R. F., Trimeche, A., Dulieu, O., Medina, Aline, Carvalho, Carla, and Faria, N. V. de Castro

Abstract

p. 1-5 Submitted by Suelen Reis (suziy.ellen@gmail.com) on 2014-04-15T14:23:08Z No. of bitstreams: 1 PhysRevLett.111.183203.pdf: 699711 bytes, checksum: 0da26fa2f8dabf69d8021b58f70a09ec (MD5) Approved for entry into archive by Rodrigo Meirelles (rodrigomei@ufba.br) on 2014-09-09T14:22:41Z (GMT) No. of bitstreams: 1 PhysRevLett.111.183203.pdf: 699711 bytes, checksum: 0da26fa2f8dabf69d8021b58f70a09ec (MD5) Made available in DSpace on 2014-09-09T14:22:41Z (GMT). No. of bitstreams: 1 PhysRevLett.111.183203.pdf: 699711 bytes, checksum: 0da26fa2f8dabf69d8021b58f70a09ec (MD5) Previous issue date: 2013 We report the direct detection of two metastable H(2S2) atoms coming from the dissociation of a single cold H2 molecule, in coincidence measurements. The molecular dissociation was induced by electron impact in order to avoid limitations by the selection rules governing radiative transitions. Two detectors, placed close to the collision center, measure the neutral metastable H(2S2) through a localized quenching process, which mixes the H(2S2) state with the H(2P2), leading to a Lyman-α detection. Our data show the accomplishment of a coincidence measurement which proves for the first time the existence of the H(2S2)-H(2S2) dissociation channel.

Published
2013
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14. Storing keV negative ions for hours: Lifetime measurements in new time domains

Author

Kaminska, M, primary, Bäckström, E, additional, Hanstorpt, D, additional, Hole, O M, additional, Nascimento, R F, additional, Blom, M, additional, Björkhage, M, additional, Källberg, A, additional, Löfgren, P, additional, Reinhed, P, additional, Rosèn, S, additional, Thomas, R D, additional, Mannervik, S, additional, Schmidt, H T, additional, and Cederquist, H, additional

Published
2015
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17. Radiative cooling of hot Cn−and CnH−molecules

Author

Kaminska, M, primary, Nascimento, R F, additional, Stockett, M H, additional, Anderson, E K, additional, Delaunay, R, additional, Vizcaino, V, additional, Rousseau, P, additional, Adoui, L, additional, Huber, B A, additional, Thomas, R D, additional, Gatchell, M, additional, Hansen, K, additional, Zettergren, H, additional, Schmidt, H T, additional, and Cederquist, H, additional

Published
2015
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18. Measuring the2D3/2Ni-excited state lifetime in DESIREE

Author

Chartkunchand, K C, primary, Hole, O M, additional, Bäckström, E, additional, Nascimento, R F, additional, Kaminska, M, additional, Davis, V T, additional, Neill, P A, additional, Thomas, R D, additional, Mannervik, S, additional, Thompson, J S, additional, Hanstorp, D, additional, Schmidt, H T, additional, and Cederquist, H, additional

Published
2015
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19. Fragmentation studies of Hydrogenated-Pyrene Polycyclic Aromatic Hydrocarbons in collisions with He

Author

de Ruette, N, primary, Gatchell, M, additional, Stockett, M H, additional, Giacomozzi, L, additional, Chen, T, additional, Anderson, E K, additional, Nascimento, R F, additional, Wolf, M, additional, Alexander, J D, additional, Delaunay, R, additional, Vizcaino, V, additional, Rousseau, P, additional, Adoui, L, additional, Huber, B A, additional, Schmidt, H T, additional, Zettergren, H, additional, and Cederquist, H, additional

Published
2015
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21. New approach for petroleum hydrocarbon degradation using bacterial spores entrapped in chitosan beads

Author

Barreto, R.V.G., Hissa, Denise Cavalcante, Paes, Fernanda Araújo, Grangeiro, T. B., Nascimento, R. F., Rebelo, Luciana Magalhães, Craveiro, A. A., and Melo, V. M. M.

Subjects
Spores, Immobilization, Chitosan, Biodegradation, Hexadecane
Abstract

Spores ofBacillus subtilisLAMI008 were entrapped in 3-mm chitosan beads and cross-linked with 0.3%glutaraldehyde forn-hexadecane biodegradation and biosurfactant recovery. When exposed to nutrients,the spores generated vegetative cells without morphological alterations as revealed by atomic forcemicroscopy. The entrapped cells degraded almost 100% of 1% ofn-hexadecane in medium supplementedwith 1% glucose and produce biosurfactant within 48 h, as well as free cells. The number of viable cellsinside the beads was maintained throughout then-hexadecane degradation process and the released bio-surfactant was not used as a carbon source. Entrapment of bacterial spores in chitosan beads overcomesproblems with stability, storage, and long term cell viability encountered with vegetative cells. Thisapproach can potentially be utilized for biodegradation of complex compounds by entrapping sporesof different species of bacteria.

Published
2010

22. Remoção de metais de solução aquosa usando bagaço de caju

Author

MOREIRA, S. A., SOUSA, F. W., OLIVEIRA, A. G., NASCIMENTO, R. F., BRITO, E. S. de, Sarah A. Moreira, UFC, Francisco W. Sousa, UFC, André G. Oliveira, UFC, Ronaldo F. Nascimento, UFC, and EDY SOUSA DE BRITO, CNPAT.

Subjects
heavy metals, Bagasse of cashew
Published
2009

26. Fast metastable hydrogen atoms from H2 molecules: twin atoms.

Author

Trimèche, A., Houdoux, D., Rahmat, G., Dulieu, O., Schneider, I. F., Medina, A., Jalbert, G., Zappa, F., de Carvalho, C. R., Nascimento, R. F., de Castro Faria, N. V., and Robert, J.

Subjects
HYDROGEN ions, METASTABLE ions, DISSOCIATION (Chemistry), ELECTRON beam research, TIME-of-flight mass spectrometry
Abstract

It is a difficult task to obtain "twin atoms", i.e. pairs of massive particles such that one can perform experiments in the same fashion that is routinely done with "twin photons". One possible route to obtain such pairs is by dissociating homonuclear diatomic molecules. We address this possibility by investigating the production of metastable H(2s) atoms coming from the dissociation of cold H2 molecules produced in a Campargue nozzle beam crossing an electron beam from a high intensity pulsed electron gun. Dissociation by electron impact was chosen to avoid limitations of target molecular excited states due to selection rules. Detectors placed several centimeters away from the collision center, and aligned with respect to possible common molecular dissociation channel, analyze the neutral fragments as a function of their time-of-flight (TOF) through Lyman-α detection. Evidence for the first time observed coincidence of pairs of H(2s) atoms obtained this way is presented [ABSTRACT FROM AUTHOR]

Published
2015
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28. N-octane catalytic isomerization with aluminium and aluminium-lanthanum pillared nontronite.

Author

Moura, C. P. de, Fernandes, M. V. S., da Silva, L. R. D., Vasconcellos, L. C. G., do Nascimento, R. F., and Valentini, A.

Subjects
OCTANE, ISOMERIZATION, HYDROCARBONS, NONTRONITE, ALKANES
Abstract

Copyright of Ceramica is the property of Associacao Brasileira de Ceramica and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Published
2015
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29. Influence The USE of Pesticides in The Quality of Surface and Groundwater Located IN Irrigated Areas of Jaguaribe, Ceara, Brazil.

Author

Milhome, M. A. L., Sousa, P. L. R., Lima, F. A. F., and Nascimento, R. F.

Abstract

The irrigated area of Jaguaribe, Ceara, Brazil is considered important region of agribusiness of the country due to the installation of various fruit exporting companies. The present work has as main objective investigate twelve types of pesticides (molinate, atrazine, methyl parathion, malathion, chlorpyrifos, fenitrothion, pendimenthalin, triazophos, bentazone, azoxystrobin, propiconazole, difenoconazole) used in the region to assess the level of contamination of waters used for potable and irrigation. Analysis of pesticides were performed using chromatographic techniques (SPME-GC/MS and SPE-HPLC/DAD) through methodologies validated according to parameters recommended by ABNT. Among the 60 water samples, 48 were positive for at least one of the twelve active ingredients studied. Fungicides propiconazole and difenoconazole were detected more frequently. The total pesticide levels ranging from 0.11-17.30 μg/L were detected in the samples. The levels detected in surface and groundwater were lower than the limits established in Brazil, but 80% of the samples analyzed were above total pesticide levels established by the European Community (>0.5 μg/L). Prolonged exposure to pesticides can cause adverse effects to human health and the aquatic ecosystem [ABSTRACT FROM AUTHOR]

Published
2015

30. ESTUDO COMPARATIVO DAS PROPRIEDADES QUÍMICAS DO RESÍDUO BORRA OLEOSA ASFÁLTICA E DO LIGANTE ASFÁLTICO DE PETRÓLEO.

Author

Fernandes, P. R. N., de Alencar, A. E. V., Soares, J. B., Cavalcante, R. M., do Nascimento, R. F., Soares, S. A., and Casagrande, M. D. T.

Subjects
ASPHALT, BINDING agents, NUCLEAR magnetic resonance, FOURIER transform infrared spectroscopy, POLYCYCLIC aromatic hydrocarbons, SOLID phase extraction
Abstract

Copyright of HOLOS is the property of Instituto Federal do Rio Grande do norte - IFRN and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Published
2013

31. Simple models for the dynamic modeling of rotating tires.

Author

Delamotte, J. C., Nascimento, R. F., and Arruda, J. R. F.

Subjects
*TIRES, *DYNAMIC models, *FINITE element method, *SPECTRAL element method, *WAVENUMBER, *STANDING waves, *FREQUENCY-domain analysis
Abstract

Large Finite Element (FE) models of tires are currently used to predict low frequency behavior and to obtain dynamic model coefficients used in multi-body models for riding and comfort. However, to predict higher frequency behavior, which may explain irregular wear, critical rotating speeds and noise radiation, FE models are not practical. Detailed FE models are not adequate for optimization and uncertainty predictions either, as in such applications the dynamic solution must be computed a number of times. Therefore, there is a need for simpler models that can capture the physics of the tire and be used to compute the dynamic response with a low computational cost. In this paper, the spectral (or continuous) element approach is used to derive such a model. A circular beam spectral element that takes into account the string effect is derived, and a method to simulate the response to a rotating force is implemented in the frequency domain. The behavior of a circular ring under different internal pressures is investigated using modal and frequency/wavenumber representations. Experimental results obtained with a real untreaded truck tire are presented and qualitatively compared with the simple model predictions with good agreement. No attempt is made to obtain equivalent parameters for the simple model from the real tire results. On the other hand, the simple model fails to represent the correct variation of the quotient of the natural frequency by the number of circumferential wavelengths with the mode count. Nevertheless, some important features of the real tire dynamic behavior, such as the generation of standing waves and part of the frequency/wavenumber behavior, can be investigated using the proposed simplified model. [ABSTRACT FROM AUTHOR]

Published
2008
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32. Multiwavelength visible and white light generation by upconversion emission in Ho/Tm/Yb triply doped fluorogermanate glass-ceramic

Author

Gouveia-Neto, A. S., Bueno, L. A., Do Nascimento, R. F., Da Costa, E. B., Sidney Ribeiro, Messaddeq, Y., Universidade Federal Rural de Pernambuco, and Universidade Estadual Paulista (UNESP)

Abstract

Made available in DSpace on 2022-04-29T08:48:13Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-02-01 Energy transfer excited multiwavelength visible upconversion emission and white light generation is described in a single sample ofPbGeO 3-PbF2-CdF2 glass-ceramic triply doped with Ho/Tm/Yb under single infrared laser excitation. Blue (475 nm), green (540 nm), and red (650 nm), upconversion luminescence signals are generated, and the emissions are assigned, respectively, to thulium (1G4- 3H6), and holmium (5S2) →5F4)→5I8, 5F5→5I8 ions transitions, both excited via successive energy transfers from ytterbium ions. It is experimentally shown that with a proper combination of the rare earth ions contents, white light may be produced, with the simultaneous generation of fluorescence with controllable intensities at the wavelengths of the three primary colours in a single sample and using a single near-infrared excitation source. Departamento de Física Universidade Federal Rural de Pernambuco, Recife, PE- 52171/900 Instituto de Química UNESP, Araraquara, SP - 14800/900 Instituto de Química UNESP, Araraquara, SP - 14800/900

33. Upconversion luminescence and thermal effects in terbium-ytterbium codoped fluorogermanate glass-ceramic

Author

Gouveia-Neto, A. S., Bueno, L. A., Do Nascimento, R. F., Sundheimer, M. L., Da Costa, E. B., Sidney Ribeiro, Messaddeq, Y., Universidade Federal Rural de Pernambuco, and Universidade Estadual Paulista (UNESP)

Abstract

Made available in DSpace on 2022-04-29T08:48:13Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-02-01 Cooperative energy transfer upconversion luminescence is investigated in Tb3+/Yb3+-codoped PbGeO3-PbF 2-CdF2 glass-ceramic and its precursor glass under resonant and off resonance infrared excitation. Bright UV-visible emission signals around 384, 415, 438 nm, and 473-490, 545, 587, and 623 nm are identified as due to the 5D3(5G 6)→7Fj (J=6,5,4) and 5D 4→7Fj (J=6,5,4,3) transitions, respectively, and readily observed. The results indicate that cooperative energy transfer between ytterbium and terbium ions followed by excited state absorption are the dominant upconversion excitation mechanisms involved. Comparison of the upconversion process in a glass-ceramic sample and its glassy precursor revealed that the former present much higher upconversion efficiency. The dependence of the upconversion emission upon pump power, temperature, and doping content is also examined. Departamento de Física Universidade Federal Rural de Pernambuco, Recife, PE-52171/900 Institute de Química UNESP, Araraquara, SP-14800/900 Institute de Química UNESP, Araraquara, SP-14800/900

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