The atomic force acoustic microscopy (AFAM) technique combines the principle of atomic force microscopy
(AFM) for nanoscale imaging with the ability to detect changes in elastic modulus on a tested sample. Depending on the
mode of operation, AFAM provides qualitative and quantitative information on the effective stiffness of the probed
sample either in the form of images or point measurements. AFAM is a contact based method and as such provides
information on the sample indentation modulus from a volume that is compressed under the AFM tip. The size of the
compressed volume depends on the static load applied to the tip, tip radius, and the elastic properties of the tip and the
probed sample and thus it can be controlled. The AFAM technique can be a powerful tool for characterization of thinfilm
systems and detection of defects that are buried at a depth of about 30 nm - 150 nm. We used the AFAM method to
study various nano-thin systems. A set of nine square membranes 3.7 μm x 3.7 μm large, with thickness increasing in 30
nm steps from 30 nm to 270 nm was dry etched in silicon. AFAM qualitative images obtained on the surface of this
sample showed all the membranes allowing for their localization. In addition, we used AFAM to determine indentation
modulus of silicon oxide films Mf with the thickness varying from 7 nm to 28 nm. The values obtained for Mf varied from 80 GPa to 90 GPa and were in good agreement with the literature values.
Dynamic Atomic Force Microscopy (AFM) modes, where the cantilever is vibrated while the sample surface or tip is scanned, belong to the standard features of most commercial instruments. With these techniques images can be obtained the contrast of which depend on the elasticity of the sample surface. Quantitative determination of Young's modulus of a sample surface with AFM is a challenge, especially when stiff materials such as hard metals or ceramics are encountered. The evaluation of the cantilever vibration spectra at ultrasonic frequencies provides a way to discern local elastic data quantitatively using the flexural vibration modes. Nanocrystalline magnetic materials, multi- domain piezoelectric materials, polymeric materials, diamond-like carbon layers, silicon, and soft clay have been examined. Images obtained at the contact resonance frequencies are presented whose contrast is based on the elastic differences of the surface structure of the various materials examined. The spatial resolution is approximately 10 nm. Applying an electrical ac-field between the tip and the surface of a piezoelectric sample, images can be generated whose contrast is additionally influenced by the piezoelectric and dielectric properties of the sample. Furthermore, we present a new approach for studying friction and the stick-slip phenomenon using the torsional resonances of AFM cantilevers.
There is commonly assumed in photoacoustic studies that the answer to sinusoidal excitation to the system is sinusoidal. In the presented contribution, using so-called an open-type photoacoustic cell, the effect of thermal signal shape was evaluated. In the studies, water was used as a reference medium of well-determined thermal diffusivity. Fresh and degraded oils were selected as studied liquids. The values of (alpha) obtained for fresh oils and degraded ones are in agreement with the table reference data reported for similar kinds of oils.