Measurements of the molecular stopping cross sections of organic ring compounds

The molecular stopping cross sections of the organic ring compounds cyclopentane, cyclohexane, cyclooctane, cyclopentene, cyclohexene, 1,3-cyclohexadiene, benzene, toulene, phenylacetylene, cyclohexanone, and p-dioxane have been measured for helium ions with energies from 0.3 to 2.0 MeV. It is found that the ring structure of molecules with less than six CH2 groups in the ring as well as the nature of the bonds involved correlate with deviations from Bragg's rule as great as 14.7%. Evidence of resonance in the ring structure which correlated with the stopping cross section of the compound benzene is also observed. A qualitative relationship between chemical bond strain and deviations from Bragg's rule is given