Yashchuk L. Spin effects in the oxygen and ozone molecules and in collision complexes with molecular oxygen

Dissertation is devoted to the finding the role of spin effects in the mechanisms of intensity borrowing for the forbidden transitions in the oxygen molecule and also in intensity enhancement of these transitions in the collision complexes with the Не, Н2, С2Н4, С6Н6 molecules. The role of spin-orbit coupling in zero-field splitting of low-lying excited states of the oxygen molecule and of the 3А2 states of the ozone molecule is found out. The mechanisms of the forbidden с1Sigma u- - b1Sigma g+ transition intensity borrowing in the isolated oxygen molecule is proposed for the first time and its intensity is appraised on the ground of quantum-chemical calculations. The theory of intensity formation of the spin-forbidden transitions in the oxygen molecule is applied to number of molecules in the collision complexes. Intensities of the Wulf band in the ozone molecule are estimated with the use of different methods of calculation, basic sets and active spaces.