Scattering is one of the most powerful techniques for studying objects with size comparable to experimental radiation wavelength without necessity to sampling them, which is called in-situ characterization as opposed to the analysis of microsamples (ex-situ). Aggregates of nanoparticles are one of the most popular media in science and technology. Combustion, thermal decomposition, laser ablation, and plasma reactors are only a few of the methods used to generate particulates aggregated at the nanoscale. This book describes an ideal walk between scattering methods, experimental techniques, and numerical simulations applied to the study of nanoparticle aggregates. The first part of the book deals with laser light scattering at visible wavelengths. Different approaches using this method are presented, which allows us to gain information about nanoparticle aggregate size, number concentration and morphology without any a priori knowledge about the complex refractive indices of the constituent species. This is particularly relevant for strongly reacting environments in which the chemical composition and microstructure of the nanoparticles are continuously evolving, such as soot in flames. The second part of the book is focused on X-ray scattering. The main differences and analogies with respect to light scattering theory are presented. A general approach is introduced to present the quantities which can be measured in an experiment of Small-Angle X-ray Scattering (SAXS) on gas-phase generated aggregates of nanoparticles. Exemplary SAXS applications are introduced to show how the mechanisms of nucleation and aggregation of particles can be studied with a spatial resolution about two orders of magnitude smaller with respect to laser light scattering methods. The combined use of SAXS with other X-ray techniques, such as WAXS and NEXAFS is discussed. The complementary characters of light and X-ray scattering are emphasized by treating the topic of hierarchical nanoparticle aggregation.

Stefano di Stasio received a first-honour degree (summa cum laude) in Electronic Engineering at 
University “Federico II” in Napoli on 4th April 1991. He received the degree of Specialist in Op cs 
on 14th March 1995 from University of Florence-Italian Na onal Ins tute of Op cs (I.N.O.A.) 
directed by Prof. F.T. Arecchi defending a final thesis with maximum laude. During the years 1995-
1999 he developed his doctoral research (Ph.D.) at Istituto Motori (C.N.R.) - Dept. of Mechanical
Engineering (D.I.M.E.) of University “Federico II” in Napoli and on 8th April 1999 he received his 
Ph.D. degree defending a doctoral thesis titled “Experiments and Modeling of Light Scattering from 
Soot Fractals in Flames” He was successful in the public government applications, first, in 1996 for 
a permanent Researcher and, after, in 2001 for a Chief Scientist Researcher position at former 
Istituto Motori now CNR-STEMS, where he was the founder and Head since 2007 of the laboratory 
"Gas-Phase generated Nanostructures, Visible Light Scattering and X-ray Synchrotron Radia on 
techniques". His research interests are the processes of forma on of organic (carbon nanotubes) 
and inorganic (metal and metal oxide nanofibers, nanobelts) nanostructures obtained via aerosol 
synthesis and their characterization (SEM, TEM, XRD, XPS, SAXS, NEXAFS, Infra-Red Spectroscopy, 
Light Scattering, UV-VIS Spectroscopy, Photoluminescence). Dr di Stasio is Author of 78 papers on 
International JCR Journals and received up today over 1484 citations, with H-index 20. He was the 
unique author of 15 scientific papers and served as Referee for more than 15 International 
Scientific Journals with high IF. He was Visiting Scientist at At Lund University in December 2011, 
Division of Combustion Physics invited by Dr. Frederick Ossler and Prof Markus Aldén and in 
Novosibirsk Akademgorodok at Voevodsky Istitute of Chemical Kinetics and Combustion of Russian 
Academy of Sciences invited by Prof. Andrei A. Onischuk over the years 2008-2017.