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Titolo:
Surface investigation on chemically modified platforms for electrothermal atomic absorption spectrometry
Autore:
De Giglio, E; Sabbatini, L; Lampugnani, L; Slaveykova, VI; Tsalev, DL;
Indirizzi:
Univ Bari, Dipartimento Chim, I-70126 Bari, Italy Univ Bari Bari Italy I-70126 ari, Dipartimento Chim, I-70126 Bari, Italy CNR, Ist Chim Analit Strumentale, Area Ric Pisa, I-56010 Pisa, Italy CNR Pisa Italy I-56010 t Strumentale, Area Ric Pisa, I-56010 Pisa, Italy Univ Sofia, Fac Chem, Sofia 1126, Bulgaria Univ Sofia Sofia Bulgaria 1126 niv Sofia, Fac Chem, Sofia 1126, Bulgaria
Titolo Testata:
SURFACE AND INTERFACE ANALYSIS
fascicolo: 11, volume: 29, anno: 2000,
pagine: 747 - 753
SICI:
0142-2421(200011)29:11<747:SIOCMP>2.0.ZU;2-J
Fonte:
ISI
Lingua:
ENG
Soggetto:
THERMALLY STABILIZED IRIDIUM; HYDRIDE-FORMING ELEMENTS; CARBIDE-COATED PLATFORM; ZIRCONIUM-TREATED PLATFORMS; HIGH-MELTING CARBIDES; PERMANENT MODIFIER; QUANTITATIVE-ANALYSIS; SPECTROSCOPY; BEHAVIOR;
Keywords:
x-ray photoelectron spectroscopy (XPS); chemical modification; permanent iridium modifier; zirconium-treated graphite platform; tungsten-treated graphite platform; graphite atomizer; L'vov platform;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
20
Recensione:
Indirizzi per estratti:
Indirizzo: Sabbatini, L Univ Bari, Dipartimento Chim, Via Orabona 4, I-70126 Bari, Italy Univ Bari Via Orabona 4 Bari Italy I-70126 70126 Bari, Italy
Citazione:
E. De Giglio et al., "Surface investigation on chemically modified platforms for electrothermal atomic absorption spectrometry", SURF INT AN, 29(11), 2000, pp. 747-753

Abstract

In order to understand better the mechanism of action of a permanent modifier based on iridium deposited on graphite furnaces pretreated by carbide-forming elements (tungsten and zirconium), an XPS investigation has been carried out on samples submitted to thermal treatment simulating the experimental conditions used in electrothermal atomic absorption spectrometry (ETAAS), Platforms pretreated by tungsten and zirconium were analysed: evidence of tungsten carbide and oxides was found in the former whereas mainly oxygenated species were found on zirconium-treated platforms. In both cases the existence of species anchored to graphite substrate via oxygen and chlorine bridges has been hypothesized in order to account for the binding energy values obtained by a curve-fitting process. The deposition of iridium on either tungsten and zirconium-pretreated platforms significantly modifies theirsurface chemical composition and, in particular, promotes the formation oftungsten and zirconium species at higher oxidation state (for example, tungsten carbide is oxidized to tungsten trioxide), At the same time, a substantial decrease of the overall signal intensities was recorded, most likely due to modifiers removal from the platform surface and/or their migration into the platform subsurface region as a consequence of the thermal treatments required by the platform-modifying procedure. Possible correlations between the chemical composition of surface modifier species that are formed ongraphite substrate and previous findings obtained by ETAAS experiments andmorphological and elemental investigations have been pointed out. In particular, confirmation has been obtained that in all the modifier systems studied (tungsten, zirconium, tungsten/iridium, zirconium/iridium) there are atleast two eventual forms of the modifier at the end of the preatomization treatment, with a prevalence of oxygen-containing species. Thus, differences in thermal stabilization as well as in the ETAAS patterns of analyte atomgeneration can be ascribed reasonably to the presence of active centres that are chemically different and characterized by different morphologies. Copyright (C) 2000 John Wiley & Sons, Ltd.

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Documento generato il 28/09/20 alle ore 12:02:58