非周期系统吸收截面四极贡献的实时探测
Real-time probing of quadrupolar contributions to the absorption cross section of non-periodic systems
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中文总结 AI 辅助
研究非周期系统吸收截面四极贡献，以氢原子为基准实时绘制四极相互作用，探索均匀场和纯空间梯度下不同机制，通过动力学分析和对称性评估，为近场分子和纳米结构非微扰多极模拟奠定基础。
中文摘要 AI 辅助
多极截面的非微扰评估对于探测原子和分子对纳米尺度环境中空间非均匀电场的响应至关重要，传统偶极近似在此失效。以氢原子为分析和数值基准，我们实时绘制由瞬时电场梯度驱动的四极相互作用。研究探索了两种不同的相互作用机制。在均匀场下，多步偶极跃迁激活四极响应，导致亚1电子伏特激发态吸收。在纯空间梯度下，弱场响应由12.1电子伏特的单光子1s→3d四极共振主导，强梯度通过瞬态驱动的相干布居诱导低能受激发射。该动力学分析辅以对四极响应和外加电场对称性方面的严格评估。此方法为未来近场区域分子和纳米结构的非微扰多极模拟奠定了理论和计算基础。
英文摘要
The non-perturbative evaluation of multipolar cross sections is essential for probing atomic and molecular responses to spatially inhomogeneous electric fields characteristic of nanoscale environments where the conventional dipole approximation breaks down. Taking the hydrogen atom as an analytical and numerical benchmark, we map in real time quadrupole interactions driven by instantaneous electric field gradients. Our study explores two distinct interaction regimes. Under a uniform field, quadrupolar responses are activated by multi-step dipole transitions, responsible for sub-1~eV excited-state absorption. Conversely, under pure spatial gradients, the weak-field response is dominated by the single-photon $1s \to 3d$ quadrupole resonance at 12.1~eV, while strong gradients induce low-energy stimulated emission via transiently driven coherent populations. This dynamical analysis is complemented by a rigorous evaluation of the symmetry aspects of the quadrupole response and the applied electric field. This methodology establishes the theoretical and computational foundation for future non-perturbative multipole simulations of molecules and nanostructures in the near-field regime.
