Sani Elisa, Papi Nicolò, Mercatelli Luca, Barison Simona, Agresti Filippo, Rossi Stefano, Dell'Oro Aldo
CNR-INO National Institute of Optics, Largo E. Fermi, 6, I-50125 Firenze, Italy.
CNR-ICMATE Institute of Condensed Matter Chemistry and Technologies for Energy, Corso Stati Uniti, 4, I-35127 Padova, Italy.
Nanomaterials (Basel). 2020 Oct 29;10(11):2160. doi: 10.3390/nano10112160.
Nowadays, the use of lasers has become commonplace in everyday life, and laser protection has become an important field of scientific investigation, as well as a security issue. In this context, optical limiters are receiving increasing attention. This work focuses on the identification of the significant parameters affecting optical limiting properties of aqueous suspensions of pristine single-wall carbon nanohorns. The study is carried out on the spectral range, spanning from ultraviolet to near-infrared (355, 532 and 1064 nm). Optical nonlinear properties are systematically investigated as a function of nanohorn morphology, concentration, dimensions of aggregates, sample preparation procedure, nanostructure oxidation and the presence and concentration of surfactants to identify the role of each parameter in the nonlinear optical behavior of colloids. The size and morphology of individual nanoparticles were identified to primarily determine optical limiting. A cluster size effect was also demonstrated, showing more effective optical limiting in larger aggregates. Most importantly, we describe an original approach to identify the dominant nonlinear mechanism. This method requires simple transmittance measurements and a fitting procedure. In our suspensions, nonlinearity was identified to be of electronic origin at a 532 nm wavelength, while at 355 nm, it was found in the generation of bubbles.
如今，激光的使用在日常生活中已变得司空见惯，激光防护已成为科学研究的一个重要领域，也是一个安全问题。在此背景下，光学限幅器正受到越来越多的关注。这项工作的重点是确定影响原始单壁碳纳米角水悬浮液光学限幅特性的重要参数。该研究在从紫外到近红外（355、532和1064纳米）的光谱范围内进行。系统地研究了光学非线性特性与纳米角形态、浓度、聚集体尺寸、样品制备过程、纳米结构氧化以及表面活性剂的存在和浓度之间的关系，以确定每个参数在胶体非线性光学行为中的作用。确定单个纳米颗粒的尺寸和形态主要决定光学限幅。还证明了一种团簇尺寸效应，表明在较大的聚集体中光学限幅更有效。最重要的是，我们描述了一种识别主导非线性机制的原始方法。该方法需要简单的透过率测量和拟合程序。在我们的悬浮液中，在532纳米波长处确定非线性源于电子效应，而在355纳米处，发现非线性是由气泡的产生引起的。
