Time-dependent analytical R-matrix approach for strong-field dynamics. II. Many-electron systems

摘要

Ionization of atoms and molecules in intense low-frequency fields is a multielectron process which may leaventhe ion in different excited states. Within the adiabatic perspective on strong-field ionization, usually referrednto as optical tunneling, electrons remaining in the molecular ion are assumed to be frozen during the ionizationnprocess. In this case, the only way to excite the molecular ion during ionization is to remove an electron fromna lower-lying molecular orbital. The higher ionization potential corresponding to such processes implies thatnsuch channels are exponentially suppressed during tunneling. Here we show that correlation-induced couplingnbetween the departing electron and the core electrons removes the exponential penalty for ionic excitations,nresulting in complex attosecond dynamics of core rearrangement during strong-field ionization. We develop anmultichannel theory of strong-field ionization and demonstrate the importance of correlation-induced excitationsnin the multiphoton and tunneling regimes for N2 and CO2 molecules.