(161g) Nanoscale Mapping of Thin Films and Monolayer Coatings On Solid Interfaces Using Three-Dimensional Atom Probe Tomography

Three dimensional atom probe tomography (3DAPT) is a unique tool in the arsenal of nanoscale interfacial characterization methods. It can uniquely provide information about both the structure and composition of materials at near atomic-scale resolution. Although generally used for the characterization of three-dimensional metal and metal alloy phases, recent developments now allow atom probe tomography to be applied to soft materials and interfacial films. The work presented here focuses on the application of 3DAPT to thin film coatings and monolayers at interfaces.

The 3DAPT functions by pulse-mode field evaporation of a sample and projection of the resulting evaporated ions or molecular fragments into a position sensitive time of flight mass spectrometer. The location and identity of the projected fragments can then be resolved and reconstructed into a three-dimensional image of the sample at nanometer-scale or better resolution. In this talk, I will describe several examples of the application of 3DAPT to interfacial systems. Monolayer coatings of adsorbed ions, such as iodide, chloride or bromide anions, and self assembled alkanethiolates have been imaged on gold electrode surfaces. Various electrodeposited polymers, including poly(aniline) and poly(phenylene oxide), have been analyzed as thin films on palladium surfaces. The 3DAPT provides information about the chemical composition of the polymer films through the mass of the evaporated fragments and information about the structure of the polymer layer as well as details about the polymer-metal interface can be resolved. Complex coatings that consist of metal nanoparticles encapsulated within electrodeposited polymer films have also been imaged.