The current web calculator for electronic stopping powers exploits a) the "SRIM Module.exe" included in SRIM 2013 code (SRIM Tutorials) - whose maximum available energy is 10 GeV/amu - and b) the energy-loss equation (i.e., Eq. (2.18) in Sect. 2.1.1 of [Leroy and Rancoita (2016)]) as discussed here. The overall approach is referred to as SR-treatment framework.
Output table includes the electronic stopping power in units of Mev cm2/g (i.e., the mass electronic stopping power).
The lower energy limit is 1 eV
In SRIM treats gas targets are dealt differently from those solid. User can select the target as gas only for elemental gas targets: H, He, N, O, F, Ne, Cl, Ar, Kr, Xe, Rn.
In the present electronic stopping power to dose converter, the energy lost by the incoming particle is assumed to be fully absorbed by the medium - for instance, the medium is supposed to to be thick enough to fully absorb the kinetic energy of emitted delta rays - and the particle energy is almost constant while traversing the absorber.
For few compounds belonging to the ICRU list the parameters employed for the energy loss formula (including those for the densiity effect) are reported in Table II of Sternheimer et al. (1984).