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1.
Front Chem ; 7: 222, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31032247

RESUMO

Photoelectron/photoion imaging spectrometry employing dispersed VUV radiation from the SOLEIL synchrotron has been used to study the predissociation of N2 + states located up to 1.3 eV above the ion's first dissociation limit. Branching ratios for unimolecular decay into either N2 + or N+ were obtained by measuring coincidences between threshold electrons and mass-selected product ions, using a supersonic beam of either 14N2 or 15N2 as photoionization target. The results confirm that predissociation of the C 2 Σ u + state of 14N2 + is faster than emission to the electronic ground-state by a factor 10 or more for all vibrational levels v' ≥ 3, while for 15N2 + the two decay modes have comparable probabilities for the levels v' = 3, 4, and 5. In contrast, no significant isotope effect could be observed for the other states of N2 + identified in the photoelectron spectrum. For both 14N2 + and 15N2 + isotopologues all vibrational levels of these other states decay to an extent of at least 95% by predissociation.

2.
Contact Dermatitis ; 48(4): 181-8, 2003 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-12786720

RESUMO

The introduction of the euro has revived interest in the risk of nickel allergy due to the handling of coins. In the present work, the transfer of metallic contamination during the manipulation of coins is examined by means of leaching experiments and manipulation tests. It is shown that pre-existing metallic species present on the surface of the coins are the major source of contamination during manipulation, and that friction inherent to everyday usage contributes predominantly to their transfer to the hands. The comparison of coins as to their relative risks of metal contamination should therefore rely on tests that simulate the friction inherent in everyday human handling. Carrying out such tests with the newly issued 1 euro and 2 euro pieces, we find, contrary to long-term leaching measurements, that the euros release less nickel than previously circulated pure-nickel coins, but that this decrease is less pronounced than might have been hoped for on the basis of their surface composition. When the coins are rubbed to a shiny polish before manipulation, contamination of the fingers is reduced by more than a factor of 10. A comparison of coins used in France indicates that the introduction of the common currency has led to a fourfold reduction in contamination by nickel, while causing a 45% increase in contamination by copper.


Assuntos
Dermatite Alérgica de Contato/etiologia , Dermatoses da Mão/induzido quimicamente , Metais Pesados/efeitos adversos , Metais Pesados/química , Numismática , Ligas/efeitos adversos , Ligas/química , Cobre/efeitos adversos , Cobre/química , Europa (Continente) , Humanos , Concentração de Íons de Hidrogênio , Níquel/efeitos adversos , Níquel/química , Fatores de Risco , Zinco/efeitos adversos , Zinco/química
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