The technique of scanning force microscopy (SFM) was used to study the nanometer-scale structure of Cu(II)-exchanged hectorite thin films. Supporting data were also obtained from Electron Spin Resonance (ESR) and X-ray diffraction (XRD) techniques. The surfaces studied included pure Cu(II)-exchanged hectorite, Cu(II)-exchanged hectorite exposed to benzene and Cu(II)-exchanged hectorite exposed to aniline. SFM images of the unexposed Cu(II)-exchanged hectorite surface revealed a smooth surface composed of interlocking platelets. The lateral dimension of these platelets ranged from a few nm to about 1 μm. After exposure to refluxing benzene, the SFM showed that the platelets underwent vertical shifts in position. This is believed to have occurred from intercalated benzene that polymerized in the interlayer region. No SFM evidence was obtained for benzene polymerization on the surface of the hectorite. Hectorite films exposed to aniline at room temperature revealed a post-polymerization structure on the hectorite surface consisting of small polymer bundles. The diameter of these bundles was measured to be 300–3000 Å, similar to the structure seen on electropolymerized polyaniline films. Aniline polymerized on the surface of hectorite films at 180 °C revealed a structure similar to undoped n-methyl-pyrrolidinone (NMP) cast polyaniline films. In this case, the polymer bundles are only 300 Å in dimension on average. XRD and ESR data also indicated interlayer aniline polymerization in Cu(II) exchanged hectorite. Mechanistic considerations affecting these polymerization reactions are presented.

Amplitude modulation (AM) scanning force microscopy (SFM) is superior to frequency modulation SFM in simplicity, sensitivity, and stability, but is still replaced by the latter because it is too slow when the Q factor is high (bandwidth < 0.5 Hz for Q > 50,000 and resonant frequency ω0 < 50 kHz). We report a close-loop AM detector that has an 18 Hz bandwidth, better than 1 mHz frequency resolution and excellent response to step frequency changes even for Q ∼ 60,000 and ω0 ∼ 32 kHz. Its superiority is well shown by the comparison of magnetic force microscope images taken under the new and old AM detection modes with the tip and scan area (videotape sample) being unchanged. Also important is that shifting the driving frequency from near the resonance peak to further away from the peak does not decrease the frequency resolution as much as we expect (but can increase the response speed).

We have been researching the capability of atomic force microscopy to reveal nontopographic properties of tissue embedded in plastic and sectioned with standard electron microscopic techniques. We present topography and elasticity maps of plastic-embedded, thin sections of muscle tissue. The images show topography correlated with the normal repeating structure of the sarcomere. Elasticity mapping using force modulation revealed contrast between the actin- and myosin-rich areas. We attribute the observed contrast in elasticity to the difference in local concentrations of biological material in embedding plastic.