Effect of dynamical spectral weight redistribution on effective interactions in time-resolved spectroscopy

摘要

The redistribution of electrons in an ultrafast pump-probe experiment causessignificant changes to the effective interaction between electrons and bosonicmodes. We study the influence of these changes on pump-probe photoemissionspectroscopy for a model electron-phonon coupled system using thenonequilibrium Keldysh formalism. We show that spectral rearrangement due tothe driving field preserves an overall sum rule for the electronic self-energy,but modifies the effective electron-phonon scattering as a function of energy.Experimentally, this pump-modified scattering can be tracked by analyzing thefluence or excitation energy dependence of population decay rates and transientchanges in dispersion kinks.