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arXiv 2406.12484cond-mat.mtrl-sci
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超短XUV/XRay激光脉冲辐照聚烯烃的损伤机制

Damage mechanisms in polyalkenes irradiated with ultra-short XUV/x-ray laser pulses

N. Nikishev, N. Medvedev

AI总结:

本文针对聚烯烃对高强度超快XUV/X射线辐照的微观响应未知问题,通过XTANT-3工具包模拟损伤动力学及阈值,发现非热效应是主机制,三种聚烯烃的损伤阈值均接近0.05 eV/原子。

摘要:

尽管聚合物在激光辐照研究中应用广泛,但其对高强度超快XUV或X射线辐照的微观响应仍知之甚少。本文对比研究了烯烃同系物,使用XTANT-3混合模拟工具包测定其损伤动力学和辐照阈值剂量。该代码同时模拟非平衡电子动力学、通过非绝热电子-离子(电子-声子)耦合实现的电子与原子间能量转移、电子激发导致的原子间势非热修饰,以及随后的原子响应和损伤形成。研究表明,最低损伤阈值与脱氢、主链上各种基团脱离或聚合物链交联等局部缺陷的产生相关。在较高剂量下,分子分解导致瞬态金属液态。我们确定非热效应是损伤的主要机制,而热(电子-离子耦合)通道在飞秒脉冲辐照情况下仅轻微影响动力学。尽管所研究的烯烃聚合物性质存在显著差异,但三种材料(聚乙烯、聚丙烯和聚丁烯)的超快X射线损伤阈值剂量均非常接近~0.05 eV/原子。

英文摘要:

Although polymers are widely used in laser-irradiation research, their microscopic response to high-intensity ultrafast XUV or X-ray irradiation is still largely unknown. Here we comparatively study homologous series of alkenes. XTANT-3 hybrid simulation toolkit is used to determine their damage kinetics and irradiation threshold doses. The code simultaneously models the nonequilibrium electron kinetics, the energy transfer between electrons and atoms via nonadiabatic electron-ion (electron-phonon) coupling, nonthermal modification of the interatomic potential due to electronic excitation, and the ensuing atomic response and damage formation. It is shown that the lowest damage threshold is associated with local defect creation such as dehydrogenation, various group detachment from the backbone, or polymer strand cross-linking. At higher doses, the disintegration of the molecules leads to a transient metallic liquid state. We identify nonthermal effects as the leading mechanism of damage, whereas the thermal (electron-ion coupling) channel influences the kinetics only slightly in the case of femtosecond-pulse irradiation. Despite notably different properties of the studied alkene polymers, the ultrafast-X-ray damage threshold doses are found to be very close to ~0.05 eV/atom in all three materials: polyethylene, polypropylene, and polybutylene.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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