Novel instrumentation for the characterization of ultrafine particles

Techniques for the in situ characterization of ultrafine particles are often based on the interaction of the particles with the surrounding gas or with light. Approaches that allow a fast determination of properties as size, mass, and surface are discussed here. As carbon is an important component of combustion particles, one of the most important and abundant part of anthropogenic ultrafine particles, techniques to determine elemental carbon concentration are also discussed; these methods are based on measuring optical absorption. Besides the analysis itself, sampling and pretreatment (e.g., dilution) play a very important role in obtaining reliable results.