We have studied ionization and electron capture cross sections for single-electron removal from biological molecules (adenine, cytosine, guanine, thymine, and uracil) by proton impact at energies ranging from 30 keV/amu to 10 MeV/amu. In this investigation, the three-body distorted wave method is used. The calculations are based on the independent electron model. For electron capture process, distortion in the final channel related to the Coulomb continuum states of the active electron and the projectile in the field of residual target ion is included. In case of ionization, we take all the pair-wise Coulomb interactions, which treat all interactions on equal footing in the final channel. Moreover, the asymptotic Coulomb logarithmic phase for the relative motion of two colliding nuclei is included in the initial channel. In both processes, the molecular character of the biological target is assumed to be a linear combination of their atomic orbitals (LCAO) and, for all cases, the different atomic orbitals are described with the Roothaan-Hartree-Fock (RHF) approximation. We have also calculated the total capture cross sections using simple Bragg’s additivity rule. For electron capture, the contributions to the TCS from the core orbitals of the molecule have also been explicitly analyzed. The double differential cross sections (DDCS) for electron emission as well as the total cross sections for single ionization of only uracil molecule with fast proton impact are also calculated. The results for capture and ionization cross sections are compared with other theoretical calculations and existing experimental data. We find that our calculated results are in quite better agreement with available experimental data than the other theoretical results.

中文翻译：

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Swift Ion 从生物分子中去除单电子的电离和电子捕获截面

我们研究了电离和电子捕获截面，用于通过能量范围为 30 keV/amu 到 10 MeV/amu 的质子撞击从生物分子（腺嘌呤、胞嘧啶、鸟嘌呤、胸腺嘧啶和尿嘧啶）中去除单电子。本次调查采用三体畸变波法。计算基于独立电子模型。对于电子俘获过程，包括与活性电子的库仑连续态有关的最终通道的畸变和残留靶离子场中的射弹。在电离的情况下，我们采用所有成对的库仑相互作用，它在最终通道中平等对待所有相互作用。此外，两个碰撞核的相对运动的渐近库仑对数相位包含在初始通道中。在这两个过程中，假定生物目标的分子特征是其原子轨道 (LCAO) 的线性组合，并且在所有情况下，不同的原子轨道均使用 Roothaan-Hartree-Fock (RHF) 近似来描述。我们还使用简单的布拉格可加性规则计算了总捕获横截面。对于电子捕获，还明确分析了分子核心轨道对 TCS 的贡献。还计算了电子发射的双微分截面 (DDCS) 以及仅具有快速质子撞击的尿嘧啶分子单电离的总截面。捕获和电离截面的结果与其他理论计算和现有实验数据进行了比较。