  Partial ionization cross section experiments have been carried out recently
at the University of Innsbruck for three types of hydrocarbons, i.e. acetylene,
ethylene and propene. Cross section data fits are generated and compared to the
compilation of earlier experimental data summarized in the online database
HYDKIN [www.hydkin.de]. New data fits are brought into a suitable form to be
incorporated into the database. In order to illuminate underlying dissociation
mechanisms the energy dependence of branching ratios above energies of 20 -
30eV is reviewed in light of the present results. This is a pre-peer reviewed
version which has been submitted to Contributions to Plasma Physics.
