Back to Search Start Over

Three dimensional vectorial imaging of surface phonons

Authors :
Li, Xiaoyan
Haberfehlner, Georg
Hohenester, Ulrich
Stéphan, Odile
Kothleitner, Gerald
Kociak, Mathieu
Publication Year :
2020

Abstract

While phonons and their related properties have been studied comprehensively in bulk materials, a thorough understanding of surface phonons for nanoscale objects remains elusive. Infra-red imaging methods with photons or electrons exist, which can map these vibrational excitations down to the individual atom scale. However, no technique so far was able to directly reveal the complete three-dimensional vectorial picture of the phononic electromagnetic density of states from a nanostructured object. Using a highly monochromated electron beam in a scanning transmission electron microscope, we could visualize varying phonon signatures from nanoscale MgO cubes both as a function of the beam position, energy-loss and tilt angle. The vibrational responses were described in terms of well-defined eigenmodes and were used to tomographically reconstruct the phononic surface fields of the object, disclosing effects invisible by conventional mapping. Surface phonon applications rely critically on the way the electromagnetic field is spatially and vectorially shaped, strongly influencing the optical, thermal and electronic behavior of the materials. Such 3D information therefore promises novel insights in nanoscale physical phenomena and is invaluable to the design and optimization of nanostructures for fascinating new uses.

Details

Database :
arXiv
Publication Type :
Report
Accession number :
edsarx.2011.10825
Document Type :
Working Paper
Full Text :
https://doi.org/10.1126/science.abg0330