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MO: Fachverband Molekülphysik

MO 23: Electronic Spectroscopy II

MO 23.2: Talk

Thursday, March 17, 2011, 15:00–15:15, MER 02

Probing dissociative molecular dications by mapping of vibrational wavefunctions — •Ralph Püttner¹, Tiberiu Arion², Marko Förstel^2,3, Toralf Lischke², Melanie Mucke², Vladmir Sekushin¹, Günter Kaindl¹, Alexander Bradshaw^2,4, and Uwe Hergenhahn² — ¹Institut für Experimentalphysik, Freie Universität Berlin, Germany — ²Max-Planck-Institut für Plasmaphysik c/o Helmholtz-Zentrum Berlin, Germany — ³Max-Planck-Institut für Kernphysik, Heidelberg, Germany — ⁴Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin, Germany

We present high-resolution photoelectron-Auger electron coincidence spectra of CH₄. Since the vibrational structure in the C 1s photoelectron spectrum is resolved, Auger spectra corresponding to the vibrational levels v=0 and 1 can be extracted. These spectra display pronounced differences due to the fact that the energy spectrum of a transition to a dissociative state reflects the squares of the vibrational wavefunction, Ψ_vib(Q), in the core-ionized state. By implementing this in a simultaneous fit of both spectra we have separated the Auger transitions to all 7 states of dicationic CH₄²⁺ present in this energy region. We were able to derive the energy values and slopes of the potential energy curves of the dicationic states and have found good agreement with other experimental and theoretical results.