SAMOP 2023 – wissenschaftliches Programm

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MO: Fachverband Molekülphysik

MO 6: Poster I

MO 6.10: Poster

Dienstag, 7. März 2023, 16:30–19:00, Empore Lichthof

Probing conical intersection dynamics in the dissociative photoionization of formaldehyde — •David Chicharro Vacas, Weiyu Zhang, Thomas Pfeifer, and Robert Moshammer — 1Max-Planck-Institute für Kernphysik, Heidelberg, Germany

Conical intersections (CI) between electronic states often govern the photochemistry of molecules and radicals. Their role and characteristics have been largely studied before both theoretically and experimentally. It has been proven that CI are crucial in different photochemical reactions and are characterized by coupled electronic and nuclear dynamics, breaking the Born-Oppenheimer approximation. The neutral photofragmentation of formaldehyde has been widely studied in the past years mainly because of a great interest for the roaming pathway producing H2. However, the photoionization and dissociative photoionization (DPI) has been less studied. Experimentally, the DPI of formaldehyde has been studied and two main DPI processes were found: The H-atom loss and the molecular channel. More recently, experimental and theoretical findings allowed to predict the mechanism involved in the DPI of formaldehyde, suggesting the presence of a conical intersection that controls this mechanism. The aim of this work is to directly observe the presence of this conical intersection by using pump-probe schemes along with the reaction microscope. The 3D-ion-electron momentum coincidence measurements in a pump-probe experiment provides enough information to fully understand this process and to directly visualize the presence of the conical intersection in the experimental results.