Chemically synthesized metal nanoparticles with morphological chiral features are known to exhibit strong circular dichroism. However, we still lack understanding of the correlation between morphological and chiroptical features of plasmonic nanoparticles. To shed light on that question, single nanoparticle experiments are required. We performed photothermal circular dichroism measurements of single chiral and achiral gold nanoparticles and correlated the chiroptical response to the 3D morphology of the same nanoparticles retrieved by electron tomography. In contrast to an ensemble measurement, we show that individual particles within the ensemble display a broad distribution of strength and handedness of circular dichroism signals. Whereas obvious structural chiral features, such as helical wrinkles, translate into chiroptical ones, nanoparticles with less obvious chiral morphological features can also display strong circular dichroism signals. Interestingly, we find that even seemingly achiral nanoparticles can display large g-factors. The origin of this circular dichroism signal is discussed in terms of plasmonics and other potentially relevant factors.

中文翻译：

---

与电子层析成像相关的单个手性金纳米粒子的光热圆二色性测量

已知具有形态手性特征的化学合成的金属纳米粒子表现出强烈的圆二色性。然而，我们仍然缺乏对等离子体纳米粒子形态学和手性光学特征之间的相关性的理解。为了阐明这个问题，需要进行单纳米粒子实验。我们对单个手性和非手性金纳米粒子进行了光热圆二色性测量，并将手性光学响应与通过电子断层扫描检索到的相同纳米粒子的 3D 形态相关联。与整体测量相比，我们表明整体中的单个粒子显示出圆二色性信号强度和旋向性的广泛分布。而明显的结构手性特征，如螺旋皱纹，转化为手性特征，具有不太明显的手性形态特征的纳米粒子也可以显示出强烈的圆二色性信号。有趣的是，我们发现即使看似非手性的纳米粒子也能显示大g-因素。该圆二色性信号的起源根据等离子体和其他潜在相关因素进行了讨论。