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Laser ablation synthesis of selenium superoxide anion SeO 4 − via selenium trioxide photolysis. Time‐of‐flight mass spectrometry and ab initio calculations
Author(s) -
Alberti Milan,
Špalt Zbyněk,
PeñaMéndez Eladia María,
RamírezGalicia Guillermo,
Havel Josef
Publication year - 2005
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.2208
Subject(s) - chemistry , selenium , superoxide , mass spectrum , mass spectrometry , photochemistry , analytical chemistry (journal) , organic chemistry , chromatography , enzyme
Laser desorption/ionisation and laser ablation of solid selenium trioxide, as well as the gas‐phase behaviour of selenium trioxide, were studied. Selenium trioxide undergoes photochemical decomposition and, from the mass spectra obtained by laser desorption/ionisation time‐of‐flight mass spectrometry (LDI‐TOF‐MS), the following species were identified: O − , O 2 − , O 3 − , SeO − , SeO 2 − , SeO 3 − , SeO 4 − , Se 2 O 7 − , Se 3 O 11 − , and Se 4 O 14 − . Formation of the selenium superoxide SeO 4 −anion is described in this work for the first time. In addition, low‐abundance selenium species such as Se 2 O 8 H 2 − , Se 3 O 11 H − , and Se 4 O 15 H 2 −were also detected. The stoichiometry of all ions was confirmed via isotopic pattern modeling and/or post‐source decay (PSD) analysis. Photolysis of selenium trioxide leads partly to ozone formation. It was found that the most likely mechanisms of selenium superoxide formation are oxidation of selenium trioxide with ozone and/or reactive oxygen radicals, or photolysis of selenium trioxide tetramer (SeO 3 ) 4 . Therefore, ab initio calculations were performed to support the mass spectrometric evidence and to suggest probable geometries for selenium superoxide anion SeO 4 −and diselenium superoxide anion Se 2 O 7 − , as well as to provide insight into and/or predict possible formation pathways. It has been found that both cyclic and non‐cyclic peroxide structures of SeO 4 −and Se 2 O 7 −ions are possible. In addition, the SeO 4 structure was also calculated guided by thermodynamic considerations using Gaussian‐2 methodology, and the inferred stability of the SeO 4 neutral molecule was supported by ab initio calculations. Copyright © 2005 John Wiley & Sons, Ltd.