AAAR 31st Annual Conference
October 8-12, 2012
Hyatt Regency Minneapolis
Minneapolis, Minnesota, USA
Abstract View
Inhibition of Thermal Charging of Gold Nanoparticles by Surface Modification
CHI-TUNG CHIANG, Jeffrey Roberts, Purdue University
Abstract Number: 66 Working Group: Nanoparticles and Materials Synthesis
Abstract Thermal charging of gold aerosol nanoparticles (AuNPs) at high temperatures (>600 degrees C) has been known for over a decade. However, the mechanism for formation of multiply charged states is still not well-understood. In this work, the surfaces of mobility-selected AuNPs were chemically modified with organic functional groups, as a way of studying the mechanism for charging. AuNPs were generated by a home-built heating well in which gold pieces were placed in an alumina-coated tungsten wire basket. Aerosol particles were formed by flowing 1.5 lpm nitrogen gas over near-molten gold inside a resistively-heated basket. The surfaces of mobility-selected particles were modified in the aerosol state by reacting them with volatile organic compounds, including alcohols and amines. Changes in mobility diameter after surface modification were monitored by tandem differential mobility analysis (TDMA). Collected particle samples were characterized by transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), and Raman spectroscopy. Surface-modified particle streams were swept through a tube furnace at temperatures above 600 degrees C to evaluate changes in thermal charging efficiency. These results could show that some adsorbed layers suppress particle charging. These results suggest a strategy for inhibiting thermal charging of aerosol particles at high temperatures.