圆偏振激光场中乙烷、丙烷和丁烷的强场库仑爆炸
Strong-Field Coulomb Explosion of Ethane, Propane, and Butane in Circularly Polarized Laser Fields
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中文总结 AI 辅助
该研究用实时含时密度泛函理论，通过圆偏振激光脉冲驱动研究乙烷、丙烷和丁烷的库仑爆炸，对比线偏振场结果，表征了烷烃系列相关动力学，揭示氢损失为主的碎片化途径及不同分子断键特点。
中文摘要 AI 辅助
我们使用实时含时密度泛函理论（RT - TDDFT）研究了强圆偏振激光脉冲驱动下乙烷（C₂H₆）、丙烷（C₃H₈）和正丁烷（C₄H₁₀）的库仑爆炸。将电离动力学与相同峰值强度下沿x、y、z轴取向的线偏振场得到的结果进行基准测试。在此激光条件下，圆偏振对所有三种分子产生的电离都比任何线偏振配置更大。利用圆偏振激发，我们系统地表征了整个烷烃系列的碎片化阈值、产物分布、通道分支比和断键动力学。原子氢是所有三个系统中最丰富的碎片，表明氢损失是主要的碎片化途径。乙烷主要通过部分脱氢保留其双碳骨架，丙烷表现出最广泛的碎片化通道以及C - H和C - C键断裂之间最强的竞争，丁烷倾向于将骨架裂解为相对稳定的双碳碎片，最显著的是通过2C₂H₄ + 2H通道。对最早断键事件的分析进一步表明，C - H解离是整个系列中首选的初始碎片化步骤，尽管与C - C裂解的竞争程度取决于分子大小。
英文摘要
We investigate the Coulomb explosion of ethane (C$_2$H$_6$), propane (C$_3$H$_8$), and \textit{n}-butane (C$_4$H$_{10}$) driven by intense circularly polarized laser pulses using real-time time-dependent density functional theory (RT-TDDFT). The ionization dynamics are benchmarked against those obtained with linearly polarized fields oriented along the $x$, $y$, and $z$ axes at the same peak intensity. Under the laser conditions considered here, circular polarization produces greater ionization than any of the linearly polarized configurations for all three molecules, indicating that the rotating electric field enhances the initial electron-removal stage that triggers Coulomb explosion. Using circularly polarized excitation, we systematically characterize fragmentation thresholds, product distributions, channel branching ratios, and bond-breaking dynamics across the alkane series. Atomic hydrogen is the most abundant fragment in all three systems, demonstrating that hydrogen loss is the dominant fragmentation pathway. Ethane primarily retains its two-carbon backbone through partial dehydrogenation, propane exhibits the broadest range of fragmentation channels and the strongest competition between C--H and C--C bond cleavage within the present ensemble, and butane favors backbone cleavage into relatively stable two-carbon fragments, most notably through the $2\mathrm{C_2H_4} + 2\mathrm{H}$ channel. Analysis of the earliest bond-breaking events further shows that C--H dissociation is the preferred initial fragmentation step throughout the series, although the degree of competition with C--C cleavage depends on molecular size.
