Turkevich method is one of the most employed techniques to synthesize gold nanoparticles. Despite its simplicity, the mechanism has been an issue of debate over the past years. The general belief is that particles are formed by a classical nucleation and growth theory, originally described by LaMer's model. In the present work, we provide new experimental evidences that supports either LaMer's theory and their detractors. In the former model, it is proposed that particles are generated by a burst nucleation form the initial "seeds", from which their growth in a second and quasi-independent step. Instead, our experiments (DLS, UV-Vis and TEM measurements) support the idea that nanoparticles "seeds" tend to form large intermediate clusters at the beginning of the synthesis, that afterwards disassemble to yield the final nanoparticles. However, unlike other reports, we propose that during the cluster formation the particles do not coalesce, instead they come close to each other without losing their identity. As the synthesis continues, these clusters are progressively separated into the final particles. As a consequence, a path to synthesize ultra-narrow size nanoparticles is provided, along with their stability against salt aggregation, and shelf-time. We found that these ultra-homogeneous nanoparticles are stable for several months, making them suitable for many applications in the biomedical and analytical research.

中文翻译：

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实验证据支持在金纳米粒子的 Turkevich 合成中存在聚集/解聚步骤

Turkevich 法是合成金纳米粒子最常用的技术之一。尽管它很简单，但该机制在过去几年中一直是一个争论的问题。一般认为粒子是由经典的成核和生长理论形成的，最初由 LaMer 模型描述。在目前的工作中，我们提供了新的实验证据来支持 LaMer 的理论及其批评者。在前一个模型中，提出粒子是由爆发成核形成的初始“种子”产生的，它们在第二个和准独立的步骤中生长。相反，我们的实验（DLS、UV-Vis 和 TEM 测量）支持这样的观点，即纳米粒子“种子”倾向于在合成开始时形成大的中间簇，然后分解以产生最终的纳米颗粒。然而，与其他报告不同，我们建议在团簇形成过程中，粒子不会聚结，而是彼此靠近而不会失去其身份。随着合成的继续，这些簇逐渐分离成最终的粒子。因此，提供了合成超窄尺寸纳米粒子的途径，以及它们对盐聚集的稳定性和保存时间。我们发现这些超均质纳米粒子可稳定数月，使其适用于生物医学和分析研究中的许多应用。随着合成的继续，这些簇逐渐分离成最终的粒子。因此，提供了合成超窄尺寸纳米粒子的途径，以及它们对盐聚集的稳定性和保存时间。我们发现这些超均质纳米粒子可稳定数月，使其适用于生物医学和分析研究中的许多应用。随着合成的继续，这些簇逐渐分离成最终的粒子。因此，提供了合成超窄尺寸纳米粒子的途径，以及它们对盐聚集的稳定性和保存时间。我们发现这些超均质纳米粒子可稳定数月，使其适用于生物医学和分析研究中的许多应用。