Stopping Cross Sections of Some Hydrocarbon Gases for 40-200-keV Helium Ions

The stopping cross sections of air, C${\mathrm{H}}_4$, ${\mathrm{C}}_2$ ${\mathrm{H}}_2$, ${\mathrm{C}}_2$ ${\mathrm{H}}_4$, ${\mathrm{C}}_3$ ${\mathrm{H}}_8$, ${\left(\mathrm{C}{\mathrm{H}}_2\right)}_3$, and ${\mathrm{C}}_3$ ${\mathrm{H}}_6$ have been measured for incident helium ions in the energy range 40 to 200 keV. The data are in good agreement with previous experiment work, and have standard deviations between 2 and 6%. They obey an energy dependence $\epsilon =\beta E^{\frac{1}{2}}$ in accord with the calculation of Lindhard and Scharff. It has been shown that while there is probably an effect due to chemical binding on the helium-ion stopping cross sections of hydrocarbons, this effect is small.