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A Novel Stem-Based Mass Spectroscopic Technique: Applications to Catalytic Materials

Published online by Cambridge University Press:  10 February 2011

J. C. Yang ,
A. Singhal ,
S. Bradley  and
J. M. Gibson
J. C. Yang
Affiliation:
Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL 61801
A. Singhal
Affiliation:
Applied Materials Inc., 3100 Bowers Ave., Santa Clara, CA 95054
S. Bradley
Affiliation:
UOP, 50 East Algonquin Road, Des Plaines, IL 60017
J. M. Gibson
Affiliation:
Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL 61801
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Abstract

Very high angle (∼ 100mrad) annular dark-field (HAADF) images in a dedicated scanning transmission electron microscope (STEM) can be used to quantitatively measure the mass of a cluster on a support material. With knowledge of the annular dark field (ADF) detector efficiency, the absolute intensity of very HAADF images can be converted to elastic scattering cross-sections. By comparing the theoretical and experimental elastic scattering cross-sections, the number of atoms can be determined. Statistical measurement of absolute cross-sections from Re-6 clusters show good agreement with theoretical cross-sections. The experimental error corresponded to ±2 Re atoms. Our experiments demonstrate the exceptional stability of the Re-6 organometallic compound relative to Re-8 clusters. This technique is presently being applied to Pt clusters.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 466: Symposium G – Atomic Resolution Microscopy of Surfaces and Interfaces , 1996 , 227
Copyright
Copyright © Materials Research Society 1997

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References

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