Influence of molecular structure on stopping power of chemical species for He+ ions from a low-energy particle accelerator

Results are reported of a 10-year study of the stopping power of approx. 70 compounds in the vapor state for He+ ions of energy 0.3-2.0 MeV. The compounds include alkanes, alkenes, alkynes, n-alchols, aldehydes, ketones, ethers, organic ring compounds, sulfur-containing organic and inorganic compounds, and halogen-containing organic and inorganic compounds, and simple gases, such as H2, O2, N2, NH3, CO, and CO2. The technique of the application of the Bragg Rule, which defines the stopping power of a 2-element compound as the additive sum of the atomic stopping power of the elements, was used to interpret the results. It is demonstrated in both measured and calculated atomic stopping power that the measured hierarchy of double bond ring structure single bond holds for C, O, and S with maximum differences of approx. 28%, 17%, and 5%, respectively