Electron transfer collisions with spatially oriented CH3CN

Positive and negative ion pairs are detected in collisions of fast [5-30 eV center of mass (CM)] K atoms with CH3CN molecules oriented in space. Different products are favored by attack at different ends of the molecule. The principal negative ion is CN-, which is produced preferentially upon attack at the negative, or CN-end of the molecule. The cyanomethyl ion, CH2CN-, is observed as the energy is raised, and is preferentially produced upon attack at the positive (methyl) end of the molecule. Formation of these ions appears to proceed by electron transfer into the LUMO at either end of the molecule, followed by a curve crossing into the most exoergic channel. Neither parent ions nor electrons are detected.