Analytical proposal for the assessment of the molecular excitation levels to the mean excitation energy

MAURO VALENTE; PEDRO PÉREZ; FEDDERICO GESER

Santa Fe

Congreso; RAFA 2019; 2019

AFA

The mean excitation energy of the materials is a physical magnitude relevant to severalfields of research, such as radiation physics, space physics, and particularly medical physics,in which the energy deposition estimations of charged particles in tissue-equivalent materialsis of utmost importance. Nowadays, several theories of the stopping power of the materialsare available, with their corresponding statistical variation [1,2]. Most of the proposed frameworks depend on the mean excitation energy parameter, always represented as a geometricalaverage of the excitation and ionization levels of the atom or molecule at hand. This parameter depends straightforwardly on the atomic number Z, and its modelling is usually carriedout through numeric or empiric approximations [3,4,5]. This work proposes a theoreticalframe for the contribution of the atom or molecule excitation levels of the desired material,which does not include the ground state. Inelastic cross section parameters are implemented to test the model for liquid water, which can be retrieved from experimental data oralso theoretically calculated with quantum mechanics. The first four excited levels and thediffuse bands are taken into account, and the corresponding evolution of the contributionto the mean excitation energy is studied while adding these levels to the energy loss function.