Laser Picoscopy: Seeing valence electrons in solids with sub-Angstrom resolution
Prof. Dr. Eleftherios Goulielmakis
University of Rostock
16:15 - 17:15 Tuesday 04 May 2021 Graz University of Technology, remote - online Video: https://1drv.ms/u/s!AtN8DP2nnqYUgbUOvP3tZpwlIdly9A?e=0TSst3 The wavelength of visible light is often assumed to impose a fundamental frontier in optical microscopy. Indeed, the Abbe limit constrains the resolution of optical techniques to tens or hundreds of nanometers and makes visible light inadequate for electron-level imaging of the materials. X-ray techniques provide the adequate resolution but lack sensitivity to valence electrons. Scanning electron microscopy, on the other hand, can probe valence electrons but it is limited to conductive surfaces leaving the bulk unexplored.
We will discuss how recent efforts in strong field, laser physics of solids allow us to overcome this limit and to visualize valence electrons in solids with sub-Angstrom resolution for the first time. We will show that high harmonics [1-3] generated in bulk solids by optical fields [4,5] embody essential information that allows the direct measurement of the periodic potential and electron density of crystalline materials. This enables the establishment of a new kind of optical tomography of solids with a spatial resolution of about four orders of magnitute beyond the abbe limit.
Representative examples of our study with various crystalline materials will be used to demonstrate a resolution down to approximately 50 picometers [6].
[1] Luu T.T. et al., Nature 521,498 (2015)
[2] Garg M. et .al., Nature 538, 359 (2016)
[3] Garg M. et. al., Nat. Phot. 12,291(2018)
[4] Wirth A. et al., Science 334, 195 (2011)
[5] Hassan M. Th et al., Nature 530, 66 (2016)
[6] Lakhotia H. et.al., Nature, 583, 55 (2020)
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