1. Could you explain the significance of your article to the non-specialist? 

Large weakly bound molecular aggregates are ubiquitous. As aerosols they influence atmospheric processes and the quality of the air, in medicine they serve as promising drug delivery systems, and in astrophysics they are discussed as players in interstellar chemistry.  Infrared spectroscopy in combination with modeling unravels fundamental relations between particle properties, such as size, shape, and architecture, and the properties of the molecules from which they are built. Such fundamental studies are also of practical relevance for analytical and industrial applications as they provide essential data for remote sensing and the control of particle formation processes.

2. What has motivated you to conduct this work? 

The motivation behind the work presented was to explore the unique infrared spectroscopic properties of molecular aggregates in the size range from subnanometers to microns. Our goals were twofold: To identify the spectral signatures of intrinsic particle properties, such as size, shape, and architecture, and to understand them on a truly microscopic level, i. e. in terms of molecular properties. It is such fundamental studies that provide useful data for present day applications of particles.

3. Where do you see this work developing in the future? 

The increasing importance of large molecular aggregates in different fields will require accurate spectroscopic reference data. We thus plan to improve the analysis of spectroscopic data of particles and to extend our spectroscopic studies to other frequency ranges. 

4. Are there any particular challenges facing future research in this area? 

One of the greatest challenges is the targeted generation of model particles with well defined properties (size, shape, etc.) in the laboratory. For the analysis of the spectroscopic data, the development of new models treating many-body systems will be crucial.