Electron transfer collisions with oriented trifluoroacetic acid (CF3CO2H).

Electron transfer collisions between neutral K atoms and neutral, oriented trifluoroacetic acid molecules, CF(3)CO(2)H, 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, CF(3)CO(2)(-) ion, and this channel is favored for attack at the positive (-CO(2)H) 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 CF(3)CO(2)(-).