Diverse Applications of Surface and Colloid Chemistry in Science and Industry - Surface and Colloid Chemistry: Principles and Applications - page 214

structures in semiconductor devices, and grain sizes in nanopowders are just a few
examples out of many that can be considered as nanosized dimensions.
In nanotechnology, knowledge of the structure and composition of the materials
studied is a key requirement for understanding the materials properties of a small size.
10.2 aPPlIcatIonS oF ScannInG Probe mIcroScoPeS (Stm,
aFm, FFm) to SurFace and colloIdal chemIStry
During the end of the 20th century, a surge in the development of significantly
advanced techniques has advanced nanoscience and technology in the development
of self-assembly structures—micelles, monolayers, vesicles—biomolecules, biosen-
sors, and surface and colloidal chemistry. In fact, the current literature indicates that
there is no end to this trend regarding the vast expansion in the sensitivity and level
of information.
Typically, all humans feel “ seeing is believing ,” so the microscope has attracted
much interest for many decades in revealing what is otherwise out of sight. Its inven-
tion, and that of other visual probes, was basically initiated on the principles laid out
by the telescope (as invented by Galileo) and the light-optical microscope (as invented
by Hooke). Over the years, the magnification and resolution of microscopes have
improved. However, for humans to understand nature at its core, there is the dimension
of atoms or molecules to be investigated. This goal has been achieved, and the subject
as described here will discuss developments invented only a few decades ago.
The ultimate aim of scientists has always been to be able to see molecules while
active. In order to achieve this goal, the microscope should be able to operate under
ambient conditions. Further, all kinds of molecular interactions between a solid and
its environment (gas or liquid or solid), initially, can take place only via the surface
molecules of the interface. It is obvious that, when a solid or liquid interacts with
another phase, knowledge of the molecular structures at these interfaces is of inter-
est. The term surface is generally used in the context of gas-liquid or gas-solid
phase boundaries, while the term interface is used for liquid-liquid or liquid-solid
phases. Furthermore, many fundamental properties of surfaces are characterized by
morphology scales of the order of 1 to 20 nm (1 nm = 10 −9 m = 10 Å (Angstrom =
10 −8 cm).
Generally, the basic issues that should be addressed for these different interfaces
are as follows:
What do the molecules of a solid surface look like, and how are the character-
istics of these different from the bulk molecules? In the case of crystals, one
asks about the kinks and dislocations.
Adsorption on solid surfaces requires the same information about the structure
of the adsorbates and the adsorption site and configurations.
Solid-adsorbate interaction energy is also required, as is known from the
Hamaker theory.
Molecular recognition in biological systems (active sites on the surfaces of
macromolecule, antibody-antigen) and biological sensors (enzyme activ-
ity, biosensors).