An X-ray photoelectron spectroscopy study of the atomization of Mo from pyrolytic graphite platforms in Electrothermal Atomic Absorption Spectroscopy

• Published in: Spectrochimica acta. Part B: Atomic spectroscopy Vol. 133; pp. 1 - 8
• Main Authors: Ruiz, Frine, Benzo, Zully, Garaboto, Angel, León, Vladimir, Ruette, Fernando, Albornoz, Alberto, Brito, Joaquín L.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-07-2017
• Subjects: Electrothermal atomization atomic absorption spectroscopy; Mo atomization mechanism; Speciation; X-ray photoelectron spectroscopy; Electrothermal atomization atomic absorption spectroscopy; Mo atomization mechanism; Speciation; X-ray photoelectron spectroscopy
• ISSN: 0584-8547; 1873-3565
• DOI: 10.1016/j.sab.2017.04.009

X-ray photoelectron spectroscopy (XPS) was employed as the analytical tool for the identification of the solid state species formed during the atomization of molybdenum on a pyrolytic graphite surface used for electrothermal atomization in atomic absorption spectroscopy (ETAAS). As XPS is capable of probing the amounts of materials employed in actual ETAAS measurements, it was anticipated that it would allow obtaining more realistic results than those reported in previous works by means of techniques such as X-ray diffraction, which requires thousand-fold amounts of the analyte. The results obtained by XPS showed a distribution pattern of the oxidation states of Mo on the graphite surface as a function of the temperatures reached at each stage of the ETAAS procedure, which was correlated with the possible species formed during the drying, ashing and atomization steps. In light of the present results, a previously proposed atomization mechanism for Mo was revisited, which allowed to disprove the alleged presence of phases such as Mo4O11 at the ashing stage and of metallic Mo as a stable, intermediate phase during the Mo2C low temperature carbide formation at 1200–1900°C. It is concluded that the XPS technique allows gaining an insight into the atomization mechanism of the analyte.
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•A previously proposed mechanism of Mo atomization in ETAAS is revisited.•XPS is used as analytical tool to probe the surface of pyrolytic graphite coated platforms.•Fine details of the previous mechanism are disproved by XPS.