Time：October 28, 2016 15:00 AM
Location：Conference Room of Building No. 36
Prof. Scott L. Anderson
Department of Chemistry, The University of Utah
The surface chemistry of small metal nanoparticles can be substantially different than that observed for bulk metal or larger nanoparticles, due to differences in the availability of particular binding sites, and quantum confinement effects on electronic structure. Two approaches to probing size effects will be discussed. For very small particles, in the cluster size regime, it is practical to prepare atomically monodisperse beams of cluster ions, which we deposit on well characterized surfaces and study by surface science or electrochemical techniques. Examples of both electronic and geometric site effects will be presented to illustrate the sorts of effects seen.
For larger particles, with thousands-to-millions of atoms, the size selection approach becomes impractical, but single particle trapping techniques can be used instead. A single particle is trapped, and then its mass is measured non-destructively to high precision while the particle is heated and/or exposed to gaseous reactants. The kinetics of surface reactions can be measured with high sensitivity by tracking the mass; by carrying out measurements on a series of particles, the effects of particle size are determined. Oxidation and sublimation chemistry of carbon nanoparticles will be used to illustrate the method.
Contacts：Junxia Ding (Group 1101, 9930)