Talk given by Prof. Gianluigi Botton Dept of Materials Science and Engineering, Canadian Centre for Electron Microscopy- Brockhouse Institute for Materials Research, McMaster University, Canada Abstract: Electron energy loss spectroscopy is an invaluable technique to study the detailed structure and the chemical state of materials at unprecedented spatial resolution. In today’s modern electron microscopes, it is possible to tackle problems requiring the highest energy resolution, down to 60meV, and highest spatial resolution, down to the angstrom level, so that atomic resolved spectroscopy with high spectroscopic sensitivity and resolution can be obtained. This leads to the potential of covering excitation phenomena from the mid-infrared, soft-X-rays and even hard-X-ray regime. In this presentation, various examples of applications of electron microscopy will be given based an ultrastable double aberration-corrected and monochromated electron microscope. First of all, the detection of low-loss features in plasmonic nanostructures and nanoantennas, down to the mid-infrared part of the electron energy loss spectrum will be given, and this by directly imaging resonances down to 0.17eV, the lowest plasmonic features detected with EELS [1,2] and hybridization effects demonstrating strong field enhancements between nanostructures. I will then demonstrate examples of detailed structural and analytical work in a number of alloy nanoparticles systems ranging from fundamentals of phase stability and surface segregations to catalysts used for fuel cells. I will present test cases where one monolayer segregation observed and confirmed from EELS. Examples will cover overview of the imaging conditions used to detect core-shell ordering changes in PtFe, PtRu, PtAu alloy nanoparticles [3] and graphene [4] used for fuel cell catalysts, using a combination of high-angle annular dark-field STEM imaging, EELS elemental mapping and simulations. This powerful technique can also be used to study of the structure and substitutional effects from single atom dopants in phosphors [6] and metallic alloys [7]. [1] D. Rossouw, et al., Nano Letters 11, 1499-1504 (2011), [2] D. Rossouw, G.A. Botton, Phys. Rev. Letters 110, 066801 (2013) [3] S. Prabhudev et al., ACS Nano 7, 6103-6110, (2013), and recently submitted work. [4] S. Stambula et al., Journal of Physical Chemistry C, (2014), C 118, 3890-3900. (2014) [5] G.-Z. Zhu, G. Radtke, G.A. Botton, Nature, 490, 384, (2012) 51. [6] G. Z. Zhu; et al. Phys. Chem. Chem. Phys. 15, 11420-11426. (2013); [7] M. Bugnet; Kula, A.; Niewczas, M.; Botton, G. A., Segregation and clustering of solutes at grain boundaries in Mg-rare earth solid solutions, Acta Materialia 79, 66-73. (2014)

This event is part of the eventgroup INT Talks

Homepage
https://www.int.kit.edu/events.php

Speaker
Prof. Gianluigi Botton

McMaster University, Canada
http://materials.mcmaster.ca/faculty_staff/faculty/botton/

Organizer
Dr. Christian Kübel
Institute of Nanotechnology (INT)
Karlsruhe Institute of Technology (KIT)
Eggenstein-Leopoldshafen
Mail: christian kuebel ∂does-not-exist.kit edu

Targetgroup
Interested / Everyone