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O: Fachverband Oberflächenphysik

O 3: Mini-Symposium: Ultrafast surface dynamics at the space-time limit I

O 3.2: Hauptvortrag

Montag, 1. März 2021, 11:00–11:15, R1

Real space-time imaging of valence electron motion in molecules — •Manish Garg — Max Planck Institute for Solid State Research, Heisenbergstr. 1, 70569 Stuttgart, Germany

Chemical transformations in molecules are a consequence of valence electron motion and its eventual coupling to atomic motion, hence, tracking valence electron motion at the orbital level is the key to understanding and taming such transformations. Scanning tunnelling microscopy (STM) can passively and locally probe the valence electron density in molecules. Contemporary techniques in attosecond science, on the other hand, can generate and track the temporal evolution of a coherent superposition of quantum states of valence electrons by using strong laser fields, which can be probed only non-locally. In absence of the capability to trigger and probe electron dynamics at the single-orbital level, electron motion could only be inferred by reconstruction. Here, we demonstrate that the dynamics of coherent superposition of valence electron states generated by < 6 femtosecond long carrier-envelope-phase (CEP) stable laser pulses, can be locally probed with picometer spatial resolution and 300 attosecond temporal resolution simultaneously, at the single orbital-level with the help of an STM, defying the previously established fundamental space-time limit. We show that near fields of optical pulses confined to the apex of nanotip of an STM enable orbital imaging of electronic levels of molecules with pm resolution. We envisage that it will be possible to see a chemical bond formation dynamics through a transition state at the orbital level in the near future.