A short history of electron microscopy
It was not until the early 1920s that Ernst Ruska and Max Knoll developed the first electron microscope; an invention for which Ruska received the Nobel Prize for Physics in 1986. Almost 40 years later, Richard Feynman gave his famous lecture titled “There’s is Plenty of Room at the Bottom” (Caltech, December 29th 1959). Many consider this talk the birthplace of modern nanotechnology and a huge push for electron microscopy. Early observations using electron microscopy were dominated by physicists and biologists.
However, at about the same time of Feynman’s lecture, geoscientists, and in particular mineralogists, started to use transmission electron microscopes to study Earth materials. Some of the early work on minerals included mica (Amelinckx, 1952), clay minerals (Honjo and Mihama, 1954) and feldspar (1963). In 1965 McLaren and Phakey at the University of Cambridge published the first series of papers on the deformation behaviour of quartz using transmission electron microscopy.
In the 1950s electron microprobe analysis began developing rapidly. The first commercial scanning electron microscope and electron microprobe were available in the 1960s. In 1973 John Venables collected the first electron backscatter diffraction pattern in a scanning electron microscope, although it wasn’t until 1994 that the first, automated electron backscatter diffraction (EBSD) map was published (Kunze, 1994), initiating a new era in analysing deformed Earth materials.
In the early 2000s, electron microscopy was again revolutionised with the commercial introduction of aberration-corrected lenses. This technological breakthrough allowed, among many other things, the detailed study of graphene. Although aberration-corrected TEM is still under-utilised in Earth sciences, numerous studies have shown its potential (e.g., Marquardt et al. 2011). One of the biggest breakthroughs for Earth-material research came with the commercialisation of focused ion beam scanning electron microscopy. This allowed the extraction of site-specific samples from complex materials and revolutionised sample preparation of ultra-thin transmission electron microscopy samples to investigate the multi-scale microstructural phenomena.
The latest developments include automated mineralogy, high-resolution EBSD for strain mapping and big data-driven machine-learning approaches to quantifying the complexity of Earth materials.
Electron microscopy is a corner stone of modern Earth-materials research and, to close with the words of Richard Feynman, “There is plenty of room at the bottom”; also for the understanding of Earth materials.
Amelinckx, S. (1952). Screw dislocations in mica. Nature, 169(4301), 580-580.
Honjo, G., & Mihama, K. (1954). A study of clay minerals by electron-diffraction diagrams due to individual crystallites. Acta Crystallographica, 7(6-7), 511-513.
Kunze, K. ; Heidelbach, Florian ; Wenk, H.-R. ; Adams, B. L.: Orientation imaging microscopy of calcite rocks. In: Bunge, Hans-Joachim (ed.): Textures of Geological Materials. – Oberursel : DGM-Informationsgesellschaft , 1994 . – pp. 127-146.
Marquardt, K., Ramasse, Q. M., Kisielowski, C., & Wirth, R. (2011). Diffusion in yttrium aluminium garnet at the nanometer-scale: Insight into the effective grain boundary width. American Mineralogist, 96(10), 1521-1529.
McLaren, A. C., & Phakey, P. P. (1965). Dislocations in quartz observed by transmission electron microscopy. Journal of Applied Physics, 36(10), 3244-3246.
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