Proposal Number: CTS-9912538 Principal Investigator: David Pui Institution: University of Minnesota
The objective of this project is to experimentally and theoretically investigate the charging of nanoparticles by ions and free electrons. Electric charging of nanoparticles is presently only partially understood, and the results of this project would be of immediate interest in materials science and health science. In materials science applications to semiconductor manufacturing can be envisioned. In health science the control of airborne particulates could be of significant benefit. A fundamental study will be performed to investigate the transition and free-molecule charging theories. The study will provide information on the maximum charging efficiency that can be achieved by ion and free electron charging. An improved unpopular charge distributions involving singly and doubly charged particles, which will be a more sensitive test of charging theories than the traditional fraction-of-charge measurements. The new charger has potential applications in many fields including classification of nanoparticles, materials science, and microelectronics. Numerical solutions for the Boltzmann Collision Equation will be obtained. Experimental and theoretical challenges arise because the particle size and the mean free path of gas molecules are of the same order of magnitude under normal operating conditions. The numerical results will be validated with the experimental results obtained with the new charger. If successful, this work will have potential applications in areas such as materials synthesis, organic coatings, fuel-cell catalysis, and drug delivery.
