ELECTRON-ENERGY-LOSS DISTRIBUTIONS IN SOLID AND GASEOUS HYDROCARBONS

The dipole oscillator strength distributions for solid and for gas pha se cyclohexane, cyclohexene, 1,3-cyclohexadiene, Ip-cyclohexadiene, an d benzene were constructed from experimentally derived optical constan ts and from atomic X-ray absorption cross sections. Monte Carlo simula tions of the energy loss by electrons of initial energy from 10 keV to 1 MeV in these media were performed using cumulative inelastic cross sections obtained from a formulation incorporating the constructed dip ole oscillator strength distributions. In the solid phase, the energy loss distributions, the most probable energy losses, and the mean ener gy losses for electrons show little effect due to the conjugation of p i bonds. However, there are large differences between the gases, and t here is a considerable effect due to condensation. The most probable a nd the mean energy losses for 1 MeV incident electrons in solid cycloh exane, cyclohexene, 1,3-cyclohexadiene, 1,4-cyclohexadiene, and benzen e are in the ranges 22-24 and 47-48 eV, respectively. Comparison with data for water suggests that the values for the solid phases of hydroc arbons are acceptable approximations for the liquid phase. Density nor malized stopping powers, inelastic mean free paths, and ranges for ele ctrons in the various hydrocarbons are also presented.