SAMOP 2023 – wissenschaftliches Programm

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MO: Fachverband Molekülphysik

MO 23: Ultrafast Dynamics III (joint session MO/A)

MO 23.1: Vortrag

Freitag, 10. März 2023, 14:30–14:45, F102

Photodissociation dynamics of CH₂Br — •Lilith Wohlfart, Christian Matthaei, and Ingo Fischer — Julius-Maximilians-Universität Würzburg, 97074 Würzburg, Germany

Bromomethyl belongs to the class of organic halogen radicals. Therefore, it can potentially influence the atmosphere by reacting with the ozone layer and causing its depletion similar to HCFCs. The photoionization of bromomethyl was already investigated by several groups, including Steinbauer and coworkers. They determined the ionization energy and structure with VUV synchrotron radiation and investigated the dissociative photoionization. To obtain further insights into the dissociation of bromomethyl, we analyzed the fragments of the radical using velocity map imaging (VMI).

CH₂Br-NO₂ was used as a precursor for the halogenated methyl radical, because the weaker C-NO₂ bond can be cleaved through pyrolysis. Subsequently, laser light with 235 nm was deployed to dissociate the formed CH₂Br radical. The major dissociation pathway gave the methylene and bromine fragments which were detected with SPI at 118 nm and [1+1’]-REMPI at 356 nm respectively. With velocity map ion imaging, the translational kinetic energy distribution of the photofragments was determined. The recorded images of the bromine and methylene photofragments showed an anisotropic distribution, implying a direct dissociation.