Researchers have developed the first imaging technique that can clearly see inside molecular structures, and have used it to create 3D holograms of the atomic arrangements inside these structures. Before now, reliable imaging techniques (for example, scanning tunneling microscopy) could only scan the surfaces of molecules. The ability to peer deep inside a molecular structure and see all of the individual atoms will be essential for developing new materials and understanding their unique physical and chemical properties.
Ref: Direct Atom Imaging by Chemical-Sensitive Holography. Nano Letters (12 April 2016) | DOI: 10.1021/acs.nanolett.6b00524
In order to understand the physical and chemical properties of advanced materials, functional molecular adsorbates, and protein structures, a detailed knowledge of the atomic arrangement is essential. Up to now, if subsurface structures are under investigation, only indirect methods revealed reliable results of the atoms’ spatial arrangement. An alternative and direct method is three-dimensional imaging by means of holography. Holography was in fact proposed for electron waves, because of the electrons’ short wavelength at easily accessible energies. Further, electron waves are ideal structure probes on an atomic length scale, because electrons have a high scattering probability even for light elements. However, holographic reconstructions of electron diffraction patterns have in the past contained severe image artifacts and were limited to at most a few tens of atoms. Here, we present a general reconstruction algorithm that leads to high-quality atomic images showing thousands of atoms. Additionally, we show that different elements can be identified by electron holography for the example of FeS2.