RESUMO
We present a study on molecular-frame photoelectron angular distributions (MFPADs) of small molecules using circularly polarized synchrotron light. We find that the main forward-scattering peaks of the MFPADs are slightly tilted with respect to the molecular axis. This tilt angle is directly connected to the molecular bond length by a simple, universal formula. We apply the derived formula to several examples of MFPADs of C 1s and O 1s photoelectrons of CO, which have been measured experimentally or obtained by means of ab initio modeling. In addition, we discuss the influence of the back-scattering contribution that is superimposed over the analyzed forward-scattering peak in the case of homo-nuclear diatomic molecules such as N2.
RESUMO
The electron affinity of cerium has been measured using laser photodetachment electron spectroscopy. The electron affinity of Ce(1G4) was determined to be 0.955 +/- 0.026 eV. The data also show that Ce- has at least two bound excited states with binding energies of 0.921 +/- 0.025 eV and 0.819 +/- 0.027 eV relative to the (1G4) ground state of the cerium atom. The present experimental measurements are compared to recent calculations of the energy levels of Ce-. Strong disagreement with the most recent theoretical atomic structure calculations highlights the complicated nature of this particular lanthanide.
