The focus of this NIRT project on Investigating Nano-carbon Particles in the Atmosphere: Formation and Transormation is to gain a clearer understanding of the chemical and physical processes occurring in the formation of carbon nanoparticles and their subsequent transformation in the diesel engine exhaust. The project has three thrust areas: (1) development of theoretical and experimental methodologies to describe the formation of heavier hydrocarbons and particle inception; (2) modeling and measurement of the particle size distribution of nanoparticles formed in combustion and diesel exhaust; and (3) modeling of the optical properties of soot precursors an soot as it ages. This project includes a collaboration with the University of Naples, Italy. The Italian investigators will contribute to this activity by several measurements including optical measurements in flames, and conagulation models.