Electron Impact Induced Excited-State to Excited-State Transitions in Yb

The Yb atom (ground state electron configuration: [Xe]4f$^{14}$ 6s$^{2}$ $^{1}$S$_{0})$ is a heavy two-electron system in which spin-orbit coupling effects play a significant role in the electronic level structure. More experimental data for scattering from this atom are becoming available, motivating the application of recent theoretical methods to this system $^{1-4}$. The non-negligible role of spin-orbit coupling suggests that a relativistic theoretical formalism may be required. We have extended our scattering studies out of ground (6s$^{2} \quad ^{1}$S$_{0})$ state target atoms to excited (6s6p $^{3}$P$_{1})$ atoms using laser excitation of the atomic beam. Measurements of the inelastic differential cross section for the excitations 6s6p $^{3}$P$_{1}$ - 5d6s $^{3}$D and 6s6p $^{3}$P$_{1}$ - 6s7s $^{3}$S$_{1}$ are presented for 20 eV collision energy. Additionally, by employing circularly polarized laser light in the preparation of the $^{3}$P$_{1}$ target state, we are able to measure the P$_{3}$ Stokes parameter for these excitations. 1. P.V. Johnson et al. J. Phys. B: At. Mol. Opt. Phys. \textbf{31} 3027 (1998) 2. P.W. Zetner et al. J. Phys. B: At. Mol. Opt. Phys. \textbf{34} 1619 (2001) 3. B Predojevic et al J. Phys. B: At. Mol. Opt. Phys. \textbf{38} 1329 (2005) 4. B Predojevic et al J. Phys. B: At. Mol. Opt. Phys. \textbf{38} 3489 (2005)