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    COLLOQUIUM OF THE LABORATORY FOR COMPUTER DESIGN OF MATERIALS
        Institute for Computational Sciences and Informatics
	                      (CSI 898-Sec 001) 

    MEASURING FORCES BY ATOMIC FORCE MICROSCOPY: IMAGING, MOLECULAR
       RECOGNITION, NANOMECHANICS AND BIOSENSOR APPLICATIONS  

                            Richard J. Colton, 
        Chemistry Division, Naval Research Laboratory, Washington, DC 

Atomic force microscopy (AFM) differs from other forms of microscopy in
that a controlled force is applied to the specimen while imaging. This
imaging force can be a limitation if one is seeking to image weakly bound
adsorbates or soft materials. On the other hand, if the magnitude of the
force is measured as a function of the tip-surface separation, the chemical
and physical properties of the surface (e.g., surface forces, elasticity,
and adhesion) can be measured. Our work at NRL has focused on developing
AFM from a qualitative imaging tool to a quantitative probe of surface
forces and mechanical properties of materials including individual molecules.

The forces between the tip and surface can be used to determine the binding
interaction between individual molecules, enhance image contrast, or probe
the mechanical properties of materials. Forces can also be used to develop
novel sensors. 

	                  Monday , September 27 1999
                                  4:30 pm
                         Room 206, Science & Tech. I

Refreshments will be served.
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Find the schedule at http://www.csi.gmu.edu/lcdm/seminar/schedule.html