Quantitative Contact Spectroscopy By Atomic-Force Acoustic Microscopy

W. Arnold
Fraunhofer-Institute for Nondestructive Testing University, Bldg. 37
D-66123 Saarbrücken, Germany

Date:  Monday, September 17, 2001
Time:  3:30 p.m.
Place:  W131 Nebraska Hall


In Atomic Force Microscopy (AFM) deflection of a microfabricated elastic beam with a sensor tip at its end is used to generate high-resolution images of surfaces. Dynamic modes, where the cantilever is vibrated while the sample surface is scanned, belong to the standard equipment of most commercial instruments. With a variety of these techniques, such as Force Modulation Microscopy, Ultrasonic Force Microscopy, Scanning Local Acceleration Microscopy, or Pulsed Force Microscopy, images can be obtained which depend on the elasticity of the sample surface. However, quantitative determination of Young’s modulus of a sample surface with AFM is still a challenge especially when stiff materials such as hard metals or ceramics are encountered. In this presentation, the evaluation of the cantilever vibration spectra at ultrasonic frequencies is discussed in order to discern local elastic data quantitatively. Nanocrystalline magnetic materials, multidomain piezoelectric materials, polymeric materials, rock materials, silicon and fused silica have been examined, the latter two as a reference material.