单物体的圆二色光谱：问题、伪影与校正
Circular Dichroism Spectroscopy of Single Objects: Problems, Artifacts, and Corrections
浏览论文内容
中文总结 AI 辅助
该研究针对单物体圆二色光谱的偏振相关伪影问题，建立了理论与实验框架，实现了可靠的单物体CD测量，为相关领域应用提供了实用指南。
中文摘要 AI 辅助
分子聚集体是多种功能系统的基础，包括光合捕光复合物、有机光伏器件、光电器件和分子传感器。然而，由于本征异质性，它们的结构组织通常难以解析。在这一背景下，圆二色（CD）光谱因对分子构建块的三维组织具有敏感性而格外强大。将CD测量从系综扩展到单个物体，为探测非结晶异质系统中的超分子结构提供了独特方法。但在没有空间和取向平均的情况下，测量对左右圆偏振激发的不平衡、理想圆偏振的偏差以及与线二色耦合的偏振缺陷高度敏感，这会产生虚假CD信号。本文提出了一套系统的理论和实验框架，用于理解、量化和控制单物体CD光谱中的伪影。我们开发了主要伪影机制的数学描述，确定其在实际实现中的起源，包括基于普克尔盒的偏振调制，并建立了最小化这些伪影的策略。我们使用能在690-785 nm范围内获取单个分子聚集体CD光谱的实验实现来验证该框架。结果表明，当严格表征和控制与偏振相关的伪影时，可实现可靠的单物体CD测量。本教程综述为单物体CD光谱及其在单粒子手性、超分子光子学和生物光子学中的应用提供了统一的理论框架和实用指南。
英文摘要
Molecular aggregates are at the basis of a broad range of functional systems, including photosynthetic light-harvesting complexes, organic photovoltaics, optoelectronic devices, and molecular sensors. Their structural organization, however, is often difficult to resolve because intrinsic heterogeneity. In this context, circular dichroism (CD) spectroscopy is particularly powerful because of its sensitivity to the three-dimensional organization of molecular building blocks. Extending CD measurements from ensembles to individual objects therefore offers a unique approach to probing supramolecular architecture in heterogeneous, non-crystallizable systems. However, without spatial and orientational averaging, measurements are highly sensitive to imbalances between left- and right-circularly polarized excitation, deviations from ideal circular polarization, and polarization imperfections coupled to linear dichroism, which creates spurious CD signals. Here, we present a systematic theoretical and experimental framework for understanding, quantifying, and controlling artifacts in single-object CD spectroscopy. We develop a mathematical description of the principal artifact mechanisms, identify their origins in practical implementations, including Pockels-cell-based polarization modulation, and establish strategies for their minimization. We validate this framework using an experimental implementation capable of acquiring CD spectra from individual molecular aggregates over 690-785 nm. Our results demonstrate that reliable single-object CD measurements are achievable when polarization-related artifacts are rigorously characterized and controlled. This Tutorial Review provides a unified theoretical framework and practical guide for single-object CD spectroscopy and its application to single-particle chirality, supramolecular photonics, and biophotonics.
