| AVS 60th International Symposium and Exhibition | |
| Accelerating Materials Discovery for Global Competitiveness Focus Topic | Friday Sessions |
| Session MG+AS+EM+NS+SA+SE+SP+SS+TF-FrM |
| Session: | Novel Synthesis Approaches and Innovative Characterization Techniques Coupled with Theory & Computations |
| Presenter: | F. Behafarid, University of Central Florida |
| Authors: | F. Behafarid, University of Central Florida L.R. Merte, University of Central Florida R. Gordon, Argonne National Laboratory B. Roldan Cuenya, University of Central Florida |
| Correspondent: | Click to Email |
A combination of polarized total reflection x-ray absorption spectroscopy (XAS) and atomic force microscopy (AFM) data have been used to determine the morphological properties of the size-selected micelle-prepared Pt nanoparticles (NPs) supported on TiO2(110) and SiO2/Si(111) in an ultrahigh vacuum (UHV) environment. The Pt NPs were cleaned in UHV using an O2-plasma followed by annealing in O2 (1x10-6 mbar) at 600°C after the ex situ sample transfer. Extended X-ray absorption fine-structure (EXAFS) measurements were carried out at Argonne National Laboratory in fluorescence mode. Measurements along different orientations, namely one perpendicular and two parallel to the sample surface were carried out on the Pt NPs supported on TiO2(110). Our analysis revealed that while the Pt NPs on SiO2 remained spherical, the NPs on TiO2 wetted the substrate and adopted an epitaxial relationship with the support. It will be shown that the first shell EXAFS analysis of the data acquired along different directions provides valuable information regarding the size and aspect ratio of the NPs as well as the degree of disorder and strain in their structure. FEFF simulations were carried out on model NP shapes and the theoretical data compared with experimental EXFAS data.