Search

Your search keyword '"Nascimento, R. F."' showing total 115 results
Start Over Author "Nascimento, R. F."
115 results on '"Nascimento, R. F."'

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
Full Text
View/download PDF

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
Full Text
View/download PDF

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
Full Text
View/download PDF

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
Full Text
View/download PDF

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
Full Text
View/download PDF

9. 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

10. 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

11. Multiresidue analysis and evaluation of the matrix effect on 20 pesticides in Brazilian maize (Zea mays L.) flour

Author

Milhome, M. A. L., primary, Vieira, S. K. V., additional, Reges, B. M., additional, Fernandes, D. R., additional, Uchoa, M. L. P., additional, Pinheiro, A. I., additional, Castro, R. C., additional, Silva, V. P. A., additional, Nobre, C. A., additional, Menezes, M. G. G., additional, Silva, R. O., additional, and do Nascimento, R. F., additional

Published
2019
Full Text
View/download PDF

13. Nanoscale Metal/Metal Multilayers Electrodeposited from Ethaline

Author

Sousa, N. G., Salgueira, J. F. S., da Silva, L. T. V., do Nascimento, R. F., de Lima-Neto, P., Correia, A. N., Mubshrah, A., and Schwarzacher, W.

Abstract

Nanoscale metal/metal multilayer films electrodeposited from a single electrolyte under either potentiostatic or galvanostatic control have been widely studied. When the electrolyte contains two metal species it is possible to alternate between depositing the more noble component and an alloy of both simply by switching either the deposition potential or current density. Most work in this field has used aqueous electrolytes, but in some situations working with alternative solvents could offer advantages. Here we present results for Ni-Cu/Cu multilayers electrodeposited from an ethaline (1:2 choline chloride: ethylene glycol) electrolyte containing 1.2 M NiCl2and 0.06 M CuCl2. The deposition potential was alternated between −0.45 V vs Ag/AgCl to deposit Cu and −1.2 V at which a Ni-rich Ni-Cu alloy was expected. Specular films consisting of multiple repeats with nominal thicknesses down to 5 nm Ni-Cu/ 1 nm Cu were obtained, and their multilayer structure was confirmed by X-ray diffraction. Average composition measurements for series of multilayers in which the thickness of one of the components was maintained constant provide further insight to the multilayer deposition process.

Published
2024
Full Text
View/download PDF

24. 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
Full Text
View/download PDF

26. Radiative lifetimes of the bound excited states ofPt−

Author

Chartkunchand, K. C., 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
2016
Full Text
View/download PDF

27. Lifetime of the bound excited level inNi−

Author

Kamińska, M., primary, Davis, V. T., additional, Hole, O. M., additional, Nascimento, R. F., additional, Chartkunchand, K. C., 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, Neill, P. A., additional, Thompson, J. S., additional, Schmidt, H. T., additional, Cederquist, H., additional, and Hanstorp, D., additional

Published
2016
Full Text
View/download PDF

29. Failure of hydrogenation in protecting polycyclic aromatic hydrocarbons from fragmentation

Author

Gatchell, M., primary, Stockett, M. H., additional, de Ruette, N., additional, Chen, T., additional, Giacomozzi, L., additional, Nascimento, R. F., additional, Wolf, M., additional, Anderson, E. K., 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
Full Text
View/download PDF

30. 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
Full Text
View/download PDF

31. 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
Full Text
View/download PDF

34. 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
Full Text
View/download PDF

35. 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
Full Text
View/download PDF

36. 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
Full Text
View/download PDF

39. Storing keV Negative Ions for an Hour: The Lifetime of the MetastableP21/2olevel inS32−

Author

Bäckström, E., primary, Hanstorp, D., additional, Hole, O. M., additional, Kaminska, 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, Schmidt, H. T., additional, and Cederquist, H., additional

Published
2015
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results