Free nanoparticle characterization by optical scattered field analysis: opportunities and perspectives

Methods for the facile and in-line characterization of size distribution and physical properties of unsupported nanoparticles are of paramount importance for fundamental research and industrial applications. The state-of-the-art free nanoparticle characterization methods do not provide accuracy, high throughput, and operation easiness to support widespread use for routine characterization. In this perspective paper, we describe and discuss the opportunities provided by approaches for nanoparticle characterization based on optical measurements of the field scattered by particles. In particular, we show how insightful is the measure of both the real and the imaginary parts of the field amplitude, a task that has been considered in the past but never had a widespread exploitation. A number of opportunities are generated by this approach, in view of assessing a more efficient characterization and a better understanding of the properties of nanoparticles. We focus our attention on the capability of characterizing nanoparticles of wide interest for applications, considering cases where traditional approaches are not currently effective. Possible exploitations are both in research and in industrial environments: to validate a synthetic process, for example, or for in-line monitoring of a production plant to generate advanced process control tools, as well as decision-making tools for acting in real time during the production.