Multi-Electron Effects in Attosecond Transient Absorption of CO Molecules

Using the fully propagated time-dependent Hartree–Fock method, we identify that both the dynamic core polarization and multiorbital contributions are important in the attosecond transient absorption of CO molecules. The dynamics of core electrons effectively modifies the behaviors of electrons in the highest occupied molecular orbital, resulting in the modulation of intensity and position of the absorption peaks. Depending on the alignment angles, different inner orbitals are identified to contribute, and even dominate the total absorption spectra. As a result, multi-electron fingerprints are encoded in the absorption spectra, which shed light on future applications of attosecond transient absorption in complex systems.