Molecular oscillations are accompanied with electron density fluctuations mainly of the higher occupied orbitals. This is particularly marked for rotational motions of large substituents of aromatic molecules. Hence, the extremely rapid and non-adiabatic free electron transfer from benzyltrimethylsilanes to n-butyl chloride parent radical cations affords the existence of different short-living molecular conformers. This is indicated by a characteristic pattern of transient products including metastable radical cations and fragment radicals derived from a dissociative and very unstable ionisation product. (C) 2003 Elsevier B.V. All rights reserved.