SM07.08.02 : Advanced Characterization of Polymer-Type Materials—Element Mapping in the Electron Microscope Using EDS

5:00 PM–7:00 PM Apr 5, 2018 (America - Denver)

PCC North, 300 Level, Exhibit Hall C-E

Meiken Falke1 Tobias Salge2 Andi Kaeppel1 Ralf Terborg1

1, Bruker, Berlin, , Germany
2, Natural History Museum, London, , United Kingdom

For understanding and tuning the properties of polymers, bio- and bio-inspired polymers chemical analysis with spatial resolution on the milli- micro- and nanometer scale and even in situ is necessary. Energy dispersive X-ray spectroscopy (EDS) in the electron microscope is one method to get information on chemical composition on all those length scales and down to atomic resolution. Samples resembling a close to natural state are often highly topographic, may need in-situ analysis and can be beam sensitive. The interface between soft and hard materials, e.g. hard inclusions to enhance certain polymer properties or nanoparticles in tissue, poses another challenge for this type of analysis. The investigation of nano-sized objects and of their distribution and embedding on the nm- and even smaller scale demands for high end instrumentation on both, the microscope and detector side. Preparation artefacts and absorption effects need to be considered.
We report on the use of existing technology and on advances in instrumentation for element mapping of bulk and electron transparent samples challenging as just described. The examples range from STEM- and T-SEM (TEM in SEM) suitable samples, including single atoms in carbonaceous material [1] to highly topographic bulk samples such as porous polymers with hard inclusions [2] and crystals formed by bio-mineralization in plants, insects and bacteria.
Available low and high end detector arrangements and respective successful measurement conditions and analysis strategies will be explained. Advancement in silicon drift detector (SDD) technology provides annular and multiple detector arrangements, such as the Flat Quad (with over 1sr solid angle) [3], suitable for high take of angle experiments, and large single detector arrangements, such as an oval detector (with up to 0.7sr solid angle) for TEM [1]. Thus, efficient EDS analysis of large, topographic bulk-, electron transparent and beam sensitive samples becomes possible.
[1] Stroud R M et al. Appl. Phys. Lett. 108 163101 (2016).
[2] Da Silva Dalto DP, Master's thesis, Escola de Química, UFRJ, Rio de Janeiro, Brazil (2010).
[3] Terborg R, Rohde Microsc. Microanal. 17 (Suppl.2) 892 (2011).