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

F. GESER; P. PÉREZ; M. VALENTE

Santa Fe

Congreso; 104 Reunión Anual de la Asociación Física Argentina; 2019

Asociación Física Argentina

The mean excitation energy is a physical quantity typically needed in the calculation of the energy deposited in matter due to swift charged ions, and therefore associated with the different stopping power for charged particles theories. Most of the models utilized in literature state that this quantity could be obtained through a geometric average that include logarithmic terms of the discrete (excitation) and continuum (ionization) levels of the corresponding atom/molecule. The analytical complexity is usually so great that numerical calculations are implemented in its calculation, particularly for the liquid water, of utmost importance in the medical physics area.This work proposes a theoretical frame 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 or also theoretically calculated with quantum mechanics. The first four excited levels and the diffuse bands are taken into account, and the corresponding evolution of the contribution to the mean excitation energy is studied while adding these levels to the energy loss function, proving the convergence for su summation of n excitation levels.