Frozen samples of twelve alkanes and benzene were irradiated by Cf 252 fission
fragments in order to study secondary ion emission by means of time-of-flight
mass spectroscopy. The mass spectra are to a certain extent similar to
electron-impact spectra of gaseous samples. The pattern of the negative ions
could be assigned to dissociation after electron capture and frequent
collisional reactions in the destruction zone of the nuclear track. Due to the
substructure of the mass spectra we emphasize that the bonding type of the
negative hydrocarbon ions is mostly acetylenic. The positive ion spectra
strongly depend on the structure of the original molecules. They exhibit -
contrary to the negative ion spectra - molecular ions, cluster ions and
molecule-specific fragment ions. Model calculations were used to investigate
the possible synthesis of carbon clusters inside an expanding plasma from the
infratrack. For the ultratrack earlier molecular fragmentation calculations are
supplemented by modelling the dehydration which is best fitted if assumed to
take place subsequent to the fragmentation on a thermal time scale. The
molecular cluster distributions are calculated by an explosive breakup model of
sputtered material.