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

Abstract

DFT, SA-MCSCF, and MRMP/MCQDPT2 methods in the 6-311++G(2d) basis set are employed to consider the features of the formation reaction of key intermediates (SeOO, Se(O 2 )) and photochemical dissociation of selenium dioxide with the formation of singlet oxygen. The cross-sections of potential energy surfaces of SeO 2 , Se(O 2 ), and SeOO are constructed and the terms of their ground and excited states are analyzed at the SeOO dissociation limit with regard to spin-orbital interaction. Possible formation channels of 1 О 2 ( 1 Δ g , 1 ) g + ∑ reactive oxygen species during the decay of the excited states of selenium oxocomplexes are revealed. The effect of the spin-orbit interaction on the character of electronic spectrum transitions and zero field splitting in oxygen is estimated.

Peculiarities of formation of hydroxonium ion and its small clusters

“…Besides the above-mentioned phenomena, a number of reactions occur in the low-temperature plasma at the height above 100 km, involving cations [О + , O 2 + , O 4 + , Н + , Н 2 + , OH + , НО 2 + , H 2 O + , (О 2 + -Н 2 О), Н 3 О + , (Н 3 О + -Н 2 О), (Н 3 О + -2Н 2 О), and (Н 3 О + -ОН)], anions (О -, О 2 -, О 3 -, Н -, and ОH -), neutral atoms (О and Н [2]) and molecules (Н 2 , О 2, and Н 2 О, their intermolecular interactions removing restrictions on deactivation or singlet oxygen generation [3][4][5]; О 3 ), free radicals (ОН and НО 2 yielding excited oxygen and Н 2 О 2 molecules [6] via recombination), exited atoms {O( 1 D 1 ) [7], O( 1 S 0 )}, and excited singlet oxygen O 2 ( 1 Δ g ) [8][9][10]. Furthermore, the Н 3 О + -n(Н 2 О) (n = 1-9) small clusters existing in the gas phase may distort the radio signals.…”