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An Automated and Rapid Process for Determining Number of Atoms in Supported Ultra-Small Metal Clusters

Published online by Cambridge University Press:  02 July 2020

J.C. Yang ,
S. Bradley  and
J.M. Gibson
S. Bradley
Affiliation:
UOP, 50 East Algonquin Road, Des Plaines, IL60017
J.M. Gibson
Affiliation:
Frederick Seitzr Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL61801
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Extract

Since heterogeneous catalysis depends on surface chemistry, insights into the structure of supported catalytic materials is vital for understanding catalysis. We have developed a mass spectroscopic technique using very high angle annular dark field images in a scanning transmission electron microscope (STEM), that gives the number of atoms per cluster. We have also developed a robust interactive computer program to analyze these images rapidly. In this proceeding, we will present our method and results on analyzing ultra-small and dispersed Pt clusters on amorphous carbon, as well as our preliminary results of Pt on γ-A12 O3.

The ultra-small Pt clusters on the amorphous carbon Cu grid were made by a proprietary technique. Imaging for the STEM-based mass-spectroscopic technique was performed on a Field Emission Gun (FEG) VG HB601 STEM operated at l00kV. The absolute measured intensity from the clusters were converted to scattering cross-sections, which can then be converted to number of atoms: More details of this method can be found in Singhal, Yang and Gibson.

Type
A. Howie Symposium: Celebration of Pioneering Electron Microscopy
Information
Microscopy and Microanalysis , Volume 5 , Issue S2: Proceedings: Microscopy & Microanalysis '99, Microscopy Society of America 57th Annual Meeting, Microbeam Analysis Society 33rd Annual Meeting, Portland, Oregon August 1-5, 1999 , August 1999 , pp. 696 - 697
Copyright
Copyright © Microscopy Society of America

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References

1.Singhal, A., Yang, J.C. and Gibson, J.M., Ultramicroscopy, 67 (1997), 191.CrossRefGoogle Scholar
2.Treacy, M.M.J. and Rice, S.B., J. of Microscopy, 156 (1989), 211.CrossRefGoogle Scholar
3. The authors thank Peter Miller Dr. and Ajay Singhal Dr. (Applied Materials, CA.). This project was supported by the Department of Energy, No. DEFG02-91ER45439 as well as UOP, and involved extensive use of the facilities within the Center for Microanalysis of Materials of the Frederick Seitz Materials Research Laboratory.Google Scholar