Stopping power and CSDA range of electrons in liquid water, LiF, CaF2, and Al2O3 from the energy gap up to 433 keV

Stopping powers (SP) for electrons with energies greater than 10 keV are well described through the Bethe approximation. However, for energies below, such an approach is inadequate. SP in LiF, CaF2 and Al2O3 as the luminescent materials commonly used for dosimetry study and liquid-water are scarce at energies below 10 keV. This work investigated SP and CSDA-range of electrons in in these compounds from the energy gap up to 433 keV using the full Penn algorithm. In particular, the influence of the exciton states was evaluated. The experimental optical data were selected after a rigorous evaluation process. The results indicate that the exciton states affect the SP mainly at energies below 100 eV by up to 48%, 39%, 32% and 15% for liquid-water, LiF, CaF2 and Al2O3, respectively. Furthermore, we observed a certain relationship between the minimum excitation-energy (exciton state) and the energy at which the SP is maximum.