Laser ablation synthesis of selenium superoxide anion SeO via selenium trioxide photolysis. Time‐of‐flight mass spectrometry and ab initio calculations

Abstract

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-, O2-, O3-, SeO-, SeO2-, SeO3-, SeO4-, Se2O7-, Se3O11-, and Se4O14-. Formation of the selenium superoxide SeO4- anion is described in this work for the first time. In addition, low-abundance selenium species such as Se2O8H2-, Se3O11H-, and Se4O15H2- 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 (SeO3)4. Therefore, ab initio calculations were performed to support the mass spectrometric evidence and to suggest probable geometries for selenium superoxide anion SeO4- and diselenium superoxide anion Se2O7-, 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 SeO4- and Se2O7- ions are possible. In addition, the SeO4 structure was also calculated guided by thermodynamic considerations using Gaussian-2 methodology, and the inferred stability of the SeO4 neutral molecule was supported by ab initio calculations.

The selenium oxygen clusters SeOn (n=1–5) and their anions: Structures and electron affinities

“…Brabson et al [16]obtained vibrational frequencies of Se x O y Molecules by Matrix Infrared Spectra and Density Functional Calculations. Havel et al [17] and Alberti et al [18] studied Laser desorption/ionisation and laser ablation of SeOn + and SeOn À by Time-of-flight mass spectrometry and ab initio calculations.…”

Laser desorption/ionization and laser ablation synthesis of new selenium oxide compounds from selenium(IV) dioxide

“…The observed selenium species are most probably not adducts with oxygen (see below for post‐source decay analysis). Interestingly, some of these ions have already been described23 when LA was carried out on selenium trioxide (photolysis): SeO (143.9), Se 2 O (271.8), and Se 2 O 8 H (289.8) (the experimental m/z values are given in parentheses).…”

“…More recently, the formation of a selenium superoxide anion via selenium trioxide photolysis has been described using the LA approach. The structure of selenium(VI) tetroxide was calculated using quantum chemistry modeling 23…”

A quantum chemical study of photochemical processes in the reaction Se + O2 → SeO2 with allowance for the spin orbit interaction

“…The properties of SeO 2 selenium dioxide in the gas phase and inert matrices were studied experimentally in [10][11][12][13][14][15][16][17][18][19]. The studies on the geometric structures of selenium oxygen clusters are presented in [20][21][22][23][24][25][26][27]. Along with SeO 2 selenium dioxide, an intermediate in the form of SeOO superoxocomplex of C s symmetry were found experimentally [17].…”