The talk will review three recent experiments in Fribourg: Two-dimensional Electron Energy Loss spectra of acrylonitrile [1,2]. 2D electron collision spectra contain rich information about the motion of a nuclear wave packet on a resonant potential surface. Motion of a nuclear wave packet on a potential surface of a metastable electronic state is characterized by a competition between propagation and detachment, the wave packet ‘rains down’ along its path above the neutral potential surface and the final vibrational states carry (indirectly) information about where it rained down and thus allow us to ‘spy’ on its trajectory. The spectra of the detached electrons carry information about the packet propagation, they tell us into what mode and into which quanta the wave packet dropped, and whether it changed modes by IVR. Electrons and Ionic Liqids [3]. Electron Energy Loss Spectra spectra of four representative ILs were recorded in the energy range of electronic excitations and compared to density functional theory multireference configuration interaction (DFT/MRCI) calculations [3], with good agreement. The spectra up to about 8 eV are dominated by pi-pi* transitions of the aromatic cations. The lowest bands were identified as triplet states. The spectral region 2-8 eV was empty in the case of a cation without pi and pi* orbitals. The EEL spectrum of a saturated solution of methylene green dye in an IL band showed the methylene green EEL band at 2 eV, indicating that ILs may be used as a host to study electron collisions with nonvolatile compounds. Resonances in Electronic Excitation. Absolute elastic [4] and electronic excitation [5] cross sections were measured for pyrimidine. Emphasis was on determining details of the resonant structure by recording the cross section as a function of electron energy from threshold to 15 eV. The experimental results compare very favorably with the results of the fixed nuclei Schwinger variational (McKoy and Winstead; elastic) and R-matrix (Gorfinkiel and Masin; elastic and electronic excitation) theoretical methods. References [1] K. Regeta and M. Allan, Phys. Rev. Lett., 110 (2013) 203201 [2] K. Regeta and M. Allan, J. Chem. Phys., 142 (2015) 184307 [3] K. Regeta C. Bannwarth, S. Grimme and M. Allan, PCCP. 17 (2015) 15771 [4] K. Regeta, M. Allan, C.Winstead, V. McKoy, Z. Masin and J. D. Gorfinkiel, submitted 2015 [5] K. Regeta, M. Allan, Z. Masin and J. D. Gorfinkiel, submitted 2015

Two-dimensional electron impact spectra, electrons and ionic liquids and electronic excitation of pyrimidine

251st National Meeting (2016)

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