Probing the isomer, fluorination and bond effects in C3H6, cyclo-C3H6 and C3F6 molecules using electron impact

We have carried out experimental and theoretical studies on electron scattering from the C3H6 isomers and C3F6 molecules (per-fluoro-propene) and we report on total, differential as well as theoretical integral elastic cross-sections for these molecules. Vibrational excitation functions are also presented for the typical vibrational peaks in C3H6 and cyclo-C3H6 for the angle of 90 degrees, impact energy range of 1-16 eV and loss energies of 0.12 eV and 0.13 eV, respectively. In the cross-sections, clear differences in peak positions and magnitudes between the C3H6 isomers can be viewed as the isomer effect. The same is observed between C3H6 and C3F6 in a clear manifestation of the fluorination effect. The resemblance of the shape resonance in the cross-sections, observed at about 2.2 eV for C3H6 and 3.5 eV for C3F6, to those in C2H4 and C2F4 clearly points to the effect of the double bond in the molecular structures for these molecules. Theoretical analysis is performed to provide rationales for the scattering dynamics. (authors)