Conclusions

Epioptics is now well established, and is making a major contribution to the study of surfaces and interfaces in general, and those of semiconductors in particular. Significant advantages over conventional surface spectroscopies have been demonstrated: all pressure ranges and transparent media are accessible; insulators can be studied without the problem of charging effects; buried interfaces can be studied due to the large penetration depth of optical radiation. Epioptic techniques offer micron lateral resolution and femtosecond temporal resolution. Nondestructive, in situ characterisation of thin films, surface and interfaces in all pressure regimes is central to the development of new materials and processes, particularly in this evolving era of nanoscale structures. It is these advantages over conventional surface spectroscopies which have driven the development of epioptics.