Electron affinity of atomic scandium and yttrium and excited states of their negative ions.

Abstract

The latest experimental electron affinity (EA) values of atomic scandium and yttrium were 0.189(20) and 0.308(12) eV as reported by Feigerle et al. in 1981. The measurement accuracy of these was far lower than that of other transition elements, and no conclusive result had been made on the excited states of their negative ions. In the current work, we report more accurate EA values of Sc and Y and the electronic structure of their negative ions using the slow-electron velocity-map imaging method. The EA values of Sc and Y are determined to be 0.179 378(22) and 0.311 29(22) eV, respectively. The ground state of Sc- is identified as 3d4s24p 1D2, and the ground state is 4d5s25p 1D2 for Y-. Furthermore, several excited states of Sc- and Y- are observed: Sc- (3D1) and Y- (3D1, 3D2, 3D3, 3F2, and 3F3), and their energy levels are determined to be 1131.8(28), 1210.0(13), 1362.3(30), 1467.7(26), 1747(16), and 1987(33) cm-1, respectively.