Photofragment ion imaging from mass-selected Mg+BrCH3 complex: Dissociation mechanism following photoinduced charge transfer

We have observed fragment ion images produced by ultraviolet photodissociation of Mg+BrCH3 complex ions using a reflectron time-of-flight mass spectrometer combined with an imaging detector. The BrCH3 + fragment ion was produced after the 266-nm excitation of Mg+BrCH3. In the image of the BrCH3 + ions, a split distribution was observed parallel to the polarization direction of the photolysis laser. In calculated potential energy curves, we found a repulsive potential correlated with a dissociation limit of Mg + BrCH3 +: The calculation results indicate that the dissociation and the charge transfer occurred via non-adiabatic process after the 52A′ ← 12A′ photoexcitation. The obtained energy and angular distributions of BrCH3 + photofragments were consistent with the fast BrCH3 + formation process on the repulsive potential energy curve.