Quantum Dots : A New Regime In Science

There are music instruments in which the excited waves are mostly inside a resonance body, for example in guitars or in organ pipes, but in others it is primarily the surface which is excited, such as in drums, where there are two-dimensional waves of the excited skin. In the same way there are not only volume waves the conduction electrons but also collective excitements of surface electrons. Breaking the crystal also breaks the local symmetry at the new surface. Atoms or molecules which previously occupied a site with a symmetry corresponding to their position in the bulk lattice are now found near the surface where the transitional periodicity stops at the surface, while it is still there towards the inside of the crystal.