Imaging electronic and atomic motion in molecules

In my talk, I will show how the dynamics of coherent superposition of valence electron states generated by < 5 femtosecond long carrier-envelope-phase (CEP) stable laser pulses, can be locally probed with angstrom-scale 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 limits. Electronic motion in molecules is usually coupled with atomic motion, especially in molecules undergoing photo-induced charge/energy transfer, structural or chemical transformation. In order to understand this coupling, we have recently realized femtosecond broadband coherent anti-Stokes Raman spectroscopy (CARS) in an STM and it has enabled tracking of coherent atomic motions in a single graphene nanoribbon with sub-angstrom scale spatial, meV energy and ~30 fs temporal resolution, simultaneously. Time-resolved CARS implemented in an STM is the key to probing both electronic and atomic motion at the same time.