fluctuation electron microscopy

Fluctuation electron microscopy (FEM), originally called Variable Coherence Microscopy before decoherence effects in the sample rendered that naming moot, is a technique in electron microscopy that probes nanometer-scale or "medium-range" order in disordered materials. The first studies were performed on amorphous Si (Treacy and Gibson 1997){{cite journal|author=Treacy, Gibson|title=Diminished medium-range order observed in annealed amorphous germanium|journal=Physical Review Letters|year=1997|url=http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.78.1074|volume=78|page=1074|doi=10.1103/PhysRevLett.78.1074}} and later on hydrogenated amorphous silicon.{{cite journal|author=P. M. Voyles|author2=J. E. Gerbi|author3=M. M. J. Treacy|author4=J. M. Gibson|author5=J. R. Abelson|name-list-style=amp|title=Absence of an abrupt phase change from polycrystalline to amorphous in silicon with deposition temperature|journal=Physical Review Letters|year=2001|volume=86|page=5514|doi=10.1103/PhysRevLett.86.5514|url=http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.86.5514}}