Non-perturbative scaling behavior for net ionization of biologically relevant molecules by multiply-charged heavy-ion impact

Abstract

A recently developed model to describe proton collisions from molecules involving basic atoms such as hydrogen, carbon, nitrogen, oxygen and phosphorus (H, C, N, O, P) is extended to treat collisions with multiply charged ions. The ion-atom collisions are computed using the two-center basis generator method (TC-BGM), which has a proven track record of yielding accurate total cross sections for electron capture and ionization. The atomic net ionization cross sections are then used to assemble two models for ion-molecule collisions: an independent atom model (IAM) that follows the Bragg additivity rule (labeled IAM-AR), and also the so-called pixel-counting method (IAM-PCM). The latter yields reduced cross sections relative to IAM-AR near the maximum, since it takes into account the overlapping nature of effective cross sectional areas. The IAM-PCM for higher-charge projectiles leads to strong reductions of net ionization cross sections relative to the IAM-AR method, and is computed directly for projectile charges $Q=1,2,3$. The scaling behavior of the IAM-PCM is investigated over a wide range of energies $E$, and at high $E$ it converges towards the IAM-AR. An empirical scaling rule is established which allows to reproduce these results based on proton impact calculations. Detailed comparisons are provided for the uracil target (${\mathrm{C}}_4{\mathrm{H}}_4{\mathrm{N}}_2{\mathrm{O}}_2$), for which other theoretical as well as experimental results are available. Based on the scaling model derived from the IAM-PCM data it is shown how the experimental data for uracil and water bombarded by multiply charged ions can be reduced to effective $Q=1$ cross sections respectively, and these are compared to proton impact data.

arXiv commentRevisions applied following refereeing process

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Cited by in corpus (6)

• Two-center basis generator method calculations for Li${}^{3+}$, C${}^{3+}$ and O${}^{3+}$ ion impact on ground state hydrogen
• Calculation of Energy Loss in Antiproton Collisions with Many-Electron Systems using Ehrenfest's Theorem
• Independent atom model description of multiple ionization of water, methane, and ammonia molecules by proton impact
• Independent-atom-model coupled-channel calculations strengthen the case for interatomic Coulomb decay as a subdominant reaction channel in slow O${}^{3+}$-Ne${}_2$ collisions
• A generalized independent atom model approach for net ionization of molecules by multiply-charged heavy-ion impact
• Atomic ionization by multicharged ions interpreted in terms of poles in the velocity complex space