Electron collisions with octafluorocyclobutane, c-C4F8

We present calculated cross sections for elastic and inelastic collisions o f low-energy electrons with octafluorocyclobutane, c-C4F8. The integral ela stic cross section displays a rich resonance structure, which we analyze in terms of temporary trapping in virtual valence orbitals. The differential elastic cross sections compare well with recent measurements at energies wh ere the approximations used in the calculations are expected to be valid. I ntegral and differential cross sections for electron-impact excitation of t he lowest singlet and triplet excited states were obtained. We relate the s mall magnitude of the inelastic integral cross sections and the unusual for m of the inelastic differential cross sections to the symmetries of the ele ctronic states involved in the transition. (C) 2001 American Institute of P hysics.