Neonization method for stopping, mean excitation energy, straggling, and for total and differential ionization cross sections of CH₄, NH₃, H₂O and FH by impact of heavy projectiles

Abstract

We propose a neonization method to deal with molecules composed by hydrides of the second row of the periodic table of elements: CH 4 , NH 3 , OH 2 and FH. This method describes these ten-electron molecules as dressed atoms in a pseudo-spherical potential. We test it by covering most of the inelastic collisional magnitudes of experimental interest: ionization cross sections (total, single and double differential), stopping power, energy-loss straggling and mean excitation energy. To this end, the neonization method has been treated with different collisional formalisms, such as the continuum-distorted-wave-eikonal-initial-state, the first order Born, and the shell-wise local plasma approximations. We show that the present model reproduces the different empirical values with high reliability in the intermediate to high-energy region. We also include the expansion of the spherical wave functions in terms of Slater-type orbitals and the analytic expression for the spherical potentials. This makes it possible in the future to tackle present neonization strategy with other collisional models.

Antiproton stopping inH2andH2O

“…For the H 2 O target we reduce the multi-center problem to a central one using a neonization method proposed by Montanari and Miraglia [18], whereby the water molecule is described as a dressed pseudo-spherical atom. With molecular orientation dependence removed from the problem the probability for transition of the target from the ground state to some final sate f becomes…”

“…Embracing the ideas of Ref. [18] we approximate the multi-center nuclei Coulomb potential of H 2 O with the spherical potential…”

“…Therefore the H 2 O molecule is represented by the same model that we have previously used for Ne [17]: six p-shell electrons above a frozen Hartree-Fock core with only one-electron excitations from the outer p shell allowed. Additionally, the core wave functions for the Ne atom are replaced by the appropriate H 2 O core wave functions which are taken from the Slater basis representation presented in [18].…”

“…We have also performed electronic stopping cross section calculations for antiprotons in H 2 O using a frozencore neonization treatment proposed in [18] 20 − l and λ l chosen to be 2. The maximum orbital angular momentum of target states used in calculations was 4.…”

“…The H 2 O target is treated using a neonization method proposed by Montanari and Miraglia [18], whereby the ten-electron water molecule is described as a dressed Nelike atom in a pseudo-spherical potential. To our best knowledge there have been no other stopping power calculations for the antiproton-H 2 O system.…”