Electron Transfer Collisions with Oriented Trifluoroacetic Acid (CF3CO2H)

Electron transfer collisions between neutral K atoms and neutral, oriented trifluoroacetic acid molecules, CF3CO2H, are studied in crossed molecular beams at center of mass energies from 6 to 18 eV. An electron transfer produces a pair of ions with enough energy to escape the Coulomb attraction, and the ions are detected in separate time-of-flight mass spectrometers. The principle ions formed are K+ and the trifluoroacetate ion, CF3CO2- ion, and this channel is favored for attack at the positive (-CO2H) end of the molecule. The steric asymmetry suggests that the electron is transferred into the pi(co)* orbital. The nascent K+ perturbs the molecular symmetry, allowing electron migration to the sigma(OH)* orbital to break the O-H bond and form CF3CO2-.