Nanoparticles are found in many areas of modern life, from the black toner in a laser printer and the white pigment in paint, to self-cleaning coatings on windows. However, not all nanoparticles are useful. Soot, a by-product of incomplete combustion, can be harmful to the environment and human health. Understanding the mechanisms by which these particles are formed and grow will help us understand how their size and shape might be tuned to promote useful properties, or assist in preventing their formation in the first place.
Within the CoMo group we employ a variety of techniques to model the growth and morphology of nanoparticles. From the most fundamental level, quantum chemistry techniques are employed to determine the stable energy states of chemical species associated with the gas-phase chemistry. By performing these calculations we hope to better understand the kinetics of the complex reaction pathways that lead to nanoparticle formation. But it doesn't end there. Once the smallest particles have been formed and are in a stable state in the system, growth systems take over. These range from the coagulation of particles and surface growth processes (gas-phase chemicals reacting on the surface of the particles), to restructuring processes also known as sintering - where the surface area of the particle reduces towards that of a perfect sphere. All these processes must be modelled accurately so that we can determine the sizes and shapes of the full population of particles. The Monte Carlo techniques employed to solve the underlying population balance equation have allowed us to describe the particles in such detail that we are now able to observe the full 3-dimensional structure of individual particles.