ABSTRACT
Bringing out the significance of the intermedial regime separating atoms and molecules, and bulk matter, nanoparticles are cataloged on the basis of their composition and occurrence. The shape and size dependence of properties at nanoscale is a unique feature distinguishing them from bulk matter. Moving to metals, the occurrence of surface plasmon resonance on bulk metals and surface plasmon band phenomenon on metallic nanoparticles are described. Parameters controlling the position of surface plasmon band of nanoparticles are discussed, notably the effect of the surrounding dielectric medium, influence of agglomeration-preventing ligands and stabilizers, effect of nanoparticle size and shape as well as composition. Quantum confinement in metals and semiconductors is treated, and its effect on bandgap energies is indicated. The bandgap behavior is explained in terms of a particle-in-a-one-dimensional box model of electron behavior. Talking about quantum dots, tight-binding approach to optical bandgap (exciton energy) versus quantum dot size is outlined. Quantum dots are compared with organic fluorophores. A structure-based classification of quantum dots is laid out. Different types of quantum dots are presented depending on their composition. Capping molecules or ligands on the surfaces of quantum dots are described. After revealing the structure of graphene and carbon nanotubes, the mechanical, electrical, electronic and magnetic properties of carbon nanotubes are stated. A description of inorganic nanowires follows. Among nanoporous materials, a mention is made of nanoporous silicon, nanoporous alumina and nano-grained thin films.
