发表机构
AMOLF Institute; Seoul National University; University of Amsterdam（AMOLF研究所; 首尔大学; 阿姆斯特丹大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究提出宽带单粒子吸收圆二色光谱法，直接测量金螺旋体的吸收不对称因子，揭示单个粒子在手性响应上的显著异质性，为纳米手性光学提供新探针。
AI 中文摘要
在单粒子水平上定量测量吸收圆二色性（CD）对于理解单个手性纳米结构如何耗散光学能量至关重要，然而宽带吸收率的测量在实验上仍具挑战性。在此，我们引入了一种波长可调的积分球显微镜，通过直接的光学能量平衡，在右旋和左旋圆偏振光照射下测定单个纳米粒子的吸收率，从而实现对吸收不对称因子gabs的宽带测量。对非手性金纳米球和强各向异性金纳米棒的测量确立了表观吸收CD基线，并证明了在实验条件下最小可检测的线性二色性到圆二色性（LD-to-CD）泄漏。将该方法应用于使用L-谷胱甘肽合成的87个手性金螺旋体（L-螺旋体）和使用D-谷胱甘肽合成的96个手性金螺旋体（D-螺旋体），揭示了平均粒子级gabs值符号相反，且两个群体之间存在统计学显著差异。然而，单个粒子在响应符号、幅度、光谱位置和线形方面表现出显著的异质性。每个群体中超过三分之一的粒子表现出与其群体平均趋势相反的符号吸收CD响应。对L-螺旋体群体的相关SEM分析进一步表明，在表现出特征投影螺旋体形态的孤立粒子中，相反符号的响应持续存在，表明聚集和投影形态的总体差异不足以解释观察到的异质性。这些结果确立了宽带单粒子吸收CD光谱法作为吸收性手性光学异质性的直接探针，并揭示了被系综平均掩盖的粒子特异性响应。
英文摘要
Quantitative measurements of absorption circular dichroism (CD) at the single-particle level are essential for understanding how individual chiral nanostructures dissipate optical energy, yet broadband absorptance measurements remain experimentally challenging. Here, we introduce a wavelength-tunable integrating-sphere microscope that determines the absorptance of individual nanoparticles under right- and left-circularly polarized illumination through direct optical energy balance, enabling broadband measurement of the absorption dissymmetry factor, gabs. Measurements of achiral gold nanospheres and strongly anisotropic gold nanorods establish the apparent absorption CD baseline and demonstrate minimal detectable linear-dichroism-to-circular-dichroism (LD-to-CD) leakage under the experimental conditions. Applying this approach to 87 chiral gold helicoids synthesized using L-glutathione (L-helicoids) and 96 synthesized using D-glutathione (D-helicoids) reveals mean particle-level gabs values of opposite sign, with a statistically significant difference between the two populations. Individual particles nevertheless exhibit pronounced heterogeneity in response sign, magnitude, spectral position, and line shape. More than one-third of the particles in each population display opposite-sign absorption CD responses relative to their population-average tendency. Correlative SEM analysis of the L-helicoid population further shows that opposite-sign responses persist among isolated particles exhibiting the characteristic projected helicoid morphology, indicating that aggregation and gross differences in projected morphology are insufficient to explain the observed heterogeneity. These results establish broadband single-particle absorption CD spectroscopy as a direct probe of absorptive chiroptical heterogeneity and reveal particle-specific responses obscured by ensemble averaging.
Comments37 pages, 5 main-text figures. Supporting Information included
