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41.
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Martinez R Farenzena LS Iza P Ponciano CR Homem MG de Brito AN Wien K da Silveira EF 《Journal of mass spectrometry : JMS》2007,42(10):1333-1341
CO-NH(3) and CO-NH(3)-H(2)O ices at 25-130 K were bombarded by (252)Cf fission fragments ( approximately 65 MeV at the target surface) and the emitted secondary ions were analyzed by time-of-flight mass spectrometry (TOF-SIMS). It is observed that the mass spectra obtained from both ices have similar patterns. The production of hybrid ions (formed from CO and NH(3) molecules) emitted from CO-NH(3) ice has already been reported by R. Martinez et al., Int. J. Mass. Spectrom. 262 (2006) 195; here, the secondary ion emission and the modifications of the CO--NH(3) ice structure during the temperature increase of the ice are addressed. These studies are expected to throw light on the sputtering from planetary and interstellar ices and the possible formation of new organic molecules in CO-NH(3)-H(2)O ice by megaelectronvolt ion bombardment. The presence of water in the CO-NH(3) ice mixture generates molecular ion series such as (NH(3))(p-q)(H(2)O)(q)CO(+) and replaces the cluster series (NH(3))(n)NH(4) (+) emission by the hybrid series (NH(3))(I-i)(H(2)O)(i=1, 2...I)H(+). The distribution of NH(3) and H(2)O molecules within the cluster groups indicates that ammonia and water mix homogeneously in the icy condensate at T = 25 K. The desorption yield distribution of the cluster series (NH(3))(n)NH(4) (+) is described by the sum of two exponential functions: one, slow-decreasing, attributed to the fragmentation of the solid target into clusters; and another, fast-decreasing, due to a local sublimation followed by recombination of ammonia molecules. The analysis of the time-temperature dependence of these two yield components gives information on the formation process of molecular ions, the transient composition of the ice target and structural changes of the ice. Data suggest that the amorphous and porous structure of the NH(3) ice, formed by the condensation of the CO--NH(3) gas at T = 25 K, survives CO sublimation until the occurrence of a phase transition around 80 K, which produces a more fragile ice structure. 相似文献
43.
Couto H Mocellin A Moreira CD Gomes MP Naves de Brito A Lopes MC 《The Journal of chemical physics》2006,124(20):204311
Threshold photoelectron spectrum of ozone is presented for the first time at a resolution of 21-38 meV using synchrotron radiation in the energy region of 12-21 eV. The ionization energies of the first ionized states were determined and an interpretation of the O3 spectrum with respect to its first three ionic states, 1 2A1, 1 2B2, and 1 2A2, is presented. Above 16 eV the enhancement of the intensities of the 2 2B1, 3 2A1, and 4 2B2 band systems due to the contribution of indirect processes was observed, not accessible by conventional photoelectron spectroscopy. It was also resolved and assigned the extensive vibrational structures of ozone. Between 15.5 and 18.5 eV the main band contours are similar to those found in conventional photoelectron spectroscopy, except that our threshold photoelectron spectrum reveals extensive additional vibrational structures. The band 2 2B1 was found to present an irregular vibrational spacing DeltaE, with a minimum value of 80 meV at approximately 16.47 eV. 相似文献
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R. Feifel M. Tchaplyguine G. Öhrwall M. Salonen M. Lundwall R. R. T. Marinho M. Gisselbrecht S. L. Sorensen A. Naves de Brito L. Karlsson N. Mårtensson S. Svensson O. Björneholm 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2004,30(3):343-351
We present new results for the inner valence levels of clusters of the three inert gases Ar, Kr and Xe based on photoelectron spectroscopy studies. The inner valence levels are compared to the localised core levels and to the delocalised outer valence levels. This comparison shows a gradual change from a relatively localised behaviour for Ar inner valence 3s, over the intermediate case of Kr inner valence 4s, to a more delocalised behaviour for Xe inner valence 5s. This change correlates well with the ratio between the orbital sizes and the interatomic distances. The Kr4s intermediate case is found to exhibit characteristics of both localised and delocalised behaviour.Received: 4 May 2004, Published online: 24 August 2004PACS:
36.40.-c Atomic and molecular clusters - 36.40.Wa Charged clusters - 61.46. + w Nanoscale materials: clusters, nanoparticles, nanotubes, and nanocrystalsA. Naves de Brito: On leave from Dept. of Physics, University of Brasília, 70910-900 Brasília, Brazil. 相似文献
47.
Moraes Amanda Naves Ferreira Silva Luís Antônio Dantas de Oliveira Maysa Aparecida de Oliveira Eder Magno Nascimento Thais Leite Lima Eliana Martins Torres Ieda Maria Sapateiro Diniz Danielle Guimarães Almeida 《Journal of Thermal Analysis and Calorimetry》2020,140(5):2283-2292
Journal of Thermal Analysis and Calorimetry - Hydroxychloroquine is effectively used in the treatment for malaria, lupus erythematosus and rheumatoid arthritis. The study of drug–excipient... 相似文献
48.
Maria-Giulia Ferretti-Alloise Andr Jacot-Guillarmod Yves-Ren Naves 《Helvetica chimica acta》1970,53(3):551-555
(+)-Carquejanone and (-)-isocarquejanone have been described by their IR. spectra and configurationally studied by optical rotatory dispersion and circular dichroism (Cotton effect). The application of the octant rule confirms the configurations previously assigned by Thomas. 相似文献
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Yves-Ren Naves Andr Jacot-Guillarmod Cornlia Rodica Zanesco 《Helvetica chimica acta》1967,50(6):1461-1469
The spectra of 120 semicarbazones in the solide state have been studied between 2.5 and 16 microns in order to correlate absorptions and structures. We have considered most particularly the absorptions v(N-H) and the so-called amid-I and amid-II bands. 相似文献