Aberration-Corrected Analytical Electron Microscopy for Nanoscale Characterization and Beyond

 

Andrew A. Herzing and Ian M. Anderson

SMSD, CSTL, NIST Gaithersburg, MD 20899.

 

Knowledge of the local chemical and structural features of materials at the atomic scale is critical to the development and optimization of the next generation of technologies, and metrology methods capable of reliably determining this information comprise one of the ultimate goals of materials characterization. The modern analytical electron microscope (AEM) has proven to be a powerful instrument for locally probing the nanoscale features of materials and recent developments promise to further enhance its capabilities.  Chief among these is the ability to correct the inherent spherical aberration of the objective lens in the AEM, which had previously placed severe limitations on the resolution of both the image and spectroscopic signals associated with the instrument [1].  Correction of this aberration enables the formation of an electron probe that is approximately 0.1 nm in diameter, and which also contains a total current that is comparable to that in the uncorrected instrument [2].  Because of this powerful combination, the advent of the aberration-corrected AEM has pointed the way towards atomic-scale microanalysis.

 

One particularly powerful method of performing microanalysis in the AEM is known as hyperspectral imaging, whereby a full spectrum (X-ray, electron energy-loss, etc.) is acquired at each image pixel of an operator defined image area.  The highly redundant datasets produced in this fashion lend themselves readily to post-acquisition data mining and statistical processing, such as principal component analysis (PCA), which can further enhance the quality of microanalytical data acquired in the AEM [3,4].

 

This poster will present an overview of several applications of elementally sensitive imaging in the aberration-corrected AEM to nanoscale structures such as quantum dots and supported precious-metal catalysts.  In addition, the prospect for carrying out such analyses in three dimensions via electron tomography will also be featured.

 

[1] M. Haider, et al, Ultramicroscopy, 75, 53 (1998)

[2] M. Watanabe, et al, Microsc. & Microanal., 12, 515, (2006)

[3] M. G. Burke, et al, J. Mater. Sci., 41, 4512, (2006)

[4] P. G. Kotula et al, Microsc. & Microanal., 9, 1, (2003)

 

 

 

 

 

 

 

 

 

 

CATEGORY: Materials

Mentors Name: Ian Anderson

SMSD, CSTL

A129, 217, Stop 8371

Tel: 301-975-2860

Fax: 301-975-1321

Email: andrew.herzing@nist.gov

 

Is your mentor a member of Sigma Xi? No