多层电子ptychography中透射函数的振幅与相位恢复
On Transmission Function Amplitude and Phase Recovery in Multislice Electron Ptychography
中文总结 AI 辅助
该研究采用声子量子激发形式主义模拟4D STEM数据集，发现电子ptychography重建对热漫散散射不敏感，吸收势模型对重原子柱振幅对比度的偏差有限。
中文摘要 AI 辅助
多层电子ptychography通常通过在重建正向模型中包含吸收型物体势来解释非弹性散射，该势会衰减弹性信号。然而，热散射如何定量影响重建仍不清楚。在此，我们使用声子量子激发（QEP）形式主义，其在单次多层传播内明确分离弹性和非弹性（热漫散）散射，以模拟PbTiO₃和SrTiO₃的四维扫描透射电子显微镜（4D STEM）数据集并重建其相位和振幅。我们发现，在11至40 nm的样品厚度范围内以及不同原子种类下，QEP总数据集与仅弹性数据集的重建几乎无法区分，表明在收集的角范围内，重建对非相干热漫散散射基本不敏感。多层仅相位模拟的重建进一步证实，可观的振幅并非来自多次弹性散射，而是反映了因热散射导致的相干弹性信号衰减。将QEP仅弹性重建与吸收型多层模拟进一步比较发现，对于重Pb柱，振幅对比度偏差显著（高达17%），这源于评估4D STEM模拟吸收势时使用的近似。因此，这些结果表明，即使存在热漫散散射，重建的相位和振幅精度也未受吸收势正向模型的显著限制。
英文摘要
{Multislice electron ptychography commonly accounts for inelastic scattering by including an absorptive object potential in the reconstruction forward model that attenuates the elastic signal. However, it remains unclear how the reconstruction is quantitatively impacted by thermal scattering. Here, we use the quantum excitation of phonons (QEP) formalism, which explicitly separates elastic and inelastic (thermal diffuse) scattering within a single multislice propagation, to simulate four-dimensional scanning transmission electron microscopy (4D STEM) datasets of PbTiO$_3$ and SrTiO$_3$ and reconstruct their phase and amplitude. We find that reconstructions of the QEP total and elastic-only datasets are nearly indistinguishable across sample thicknesses from 11 to 40 nm and across atomic species, demonstrating that the reconstruction is largely insensitive to incoherent thermal diffuse scattering within the collected angular range. Reconstructions from multislice phase-only simulations further confirm that appreciable amplitude does not arise from multiple elastic scattering, but instead reflects attenuation of the coherent elastic signal due to thermal scattering. Further comparison of the QEP elastic-only reconstruction with absorptive multislice simulations reveals substantial amplitude contrast deviations for heavy Pb columns (up to 17\%), arising from the approximations used to evaluate the absorptive potential for the 4D STEM simulation. These results thus indicate that reconstruction phase and amplitude accuracy are not significantly limited by the absorptive potential forward model, even in the presence of thermal diffuse scattering.
