Matrix infrared spectra and theoretical studies of thorium oxide species: ThOx and Th2Oy

Infrared spectra of three new thorium oxide species have been obtained in argon and neon matrixes. All of the products are experimentally characterized using isotopic oxygen samples with the aid of electronic structure calculations. Ground state thorium atoms react with O(2) to form the ThO(2) molecules, which can dimerize to give Th(2)O(4) products. Th(2)O(4) is predicted to have nonplanar C(2h) symmetry for its closed shell singlet ground state. The rhombus-shaped Th(2)O(2) molecule in the (1)A(g) (D(2h)) ground state is also observed and its formation is proposed via the reaction of Th(2) with O(2). In addition, electron capture of neutral thorium dioxide results in the formation of the ThO(2)(-) anion. It is predicted to have a doublet ground state with a geometry similar to that of the neutral ThO(2) molecule. Electronic structure calculations on the unobserved Th(2)O and Th(2)O(3) molecules are also provided.