Full Ab Initio Many-Electron Simulation of Attosecond Molecular Pump–Probe Spectroscopy

Here, we present an ab initio approach to full simulation of an attosecond molecular pump–probe experiment. Sequential molecular double ionization by the pump and probe laser pulses with controlled delay is described from first-principles with a full account of the continuum dynamics of the photoelectrons. Many-electron bound-continuum dynamics is simulated using the time-dependent (TD) molecular B-spline algebraic diagrammatic construction (ADC) method. Our calculations give a quantitative prediction about the creation of a coherent superposition of molecular ionic states in the photoionization process and simulate the probe of the ensuing attosecond dynamics by a second ionizing pulse within a single first-principles many-electron framework. We therefore demonstrate the capability to simulate and interpret the results of a prototypical molecular pump–probe experiment of interest in attoscience. As a particular example, we simulate and elucidate the interpretation of a pump–probe experiment in CO2 aimed at measuring strong field-induced hole dynamics via photoionization yields.