Time-Resolving Attosecond Coherent Electron Motion

Charge migration, the coherent motion of charge driven by purely electronic dynamics, may play an important role in chemical reactions and offer an avenue towards engineering reaction pathways. The typical energy splitting of valence states in small molecules is on the order of electron volts, which results in coherent dynamics on the attosecond timescale. Exploiting recent developments in attosecond x-ray pulse pair generation at the LCLS, we time-resolve charge migration in meta-aminophenol. An x-ray pump pulse ionizes the molecule, generating a coherent superposition of valence-ionized states. We then probe the hole density in the vicinity of the oxygen site through the amplitude of the resonant transition between the oxygen core electrons and the hole. The effect of the zero-point spread of the nuclear wavepacket on the dephasing of the coherent motion is observed.