The increasing importance of studies on soft matter and their impact on new technologies, including those associated with nanotechnology, has brought intermolecular and surface forces to the forefront of physics and materials science, for these are the prevailing forces in micro and nanosystems. With experimental methods such as the atomic force spectroscopy (AFS), it is now possible to measure these forces accurately, in addition to providing information on local material properties such as elasticity, hardness and adhesion. This review provides the theoretical and experimental background of AFS, adhesion forces, intermolecular interactions and surface forces in air, vacuum and in solution.

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Precursor glass and glass-ceramics with molar composition 2Na2O • ICaO • 3SiO2 are studied by infrared, conventional, and microprobe Raman techniques. The Gaussian deconvoluted Raman spectrum of the glass presents bands at 625 and 660 cm~], attributed to bending vibrations of S i -O -S i bonds, and at 860, 920, 975, and 1030 cm"1, attributed to symmetric stretching vibrations of SiO4 tetrahedra with 4, 3, 2, and 1 nonbridging oxygens, respectively. The Raman microprobe spectrum of a highly crystallized sample presents two narrow and intense bands at about 590 and 980 cm^1, associated with vibrations of SiO4 tetrahedra with two nonbridging oxygens, in agreement with the predicted chain-like structure of crystalline metasilicates. Scanning electron microscopy shows that the crystals distributed in partially crystallized samples have a spherical shape, built up by radially oriented needle-like single crystals. The Raman microprobe spectra of these spherulites show that they still contain residual amorphous material. A comparison of Raman and infrared spectra of amorphous and highly crystallized samples is presented.

Applying high dc electric fields at elevated temperatures on silicate glasses results in displacement of ions, causing compositional and structural changes in the anodic surface. In this work, the ionic displacement was accompanied by electric current measurements during poling. The thickness of the Na + depletion layer calculated from the current curves agrees with the thickness measured by EDS only if displacement of Ca 2+ and O − are also taken into account. A depletion of Ca 2+ in the anodic surface has in fact been observed. Structural changes were confirmed by infrared diffuse and specular reflectance spectroscopies. A narrowing of the band at about 1070 cm −1 can be attributed to an increase in the structural ordering degree. Refractive index measurements confirm compositional changes and contact angle measurements indicate the existence of a negative charge density at the anodic surface.

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