A combined experimental and theoretical study of relaxation dynamics in the charge-density-wave system TbTe3 shows, how a dynamical insulator-to-metal transition affects fundamental interactions, such as electron-electron and electron-phonon scattering. Time- and angle-resolved photoemission spectroscopy utilizes optical excitation to transiently alter the energy gap and reveals a concurrent, highly unusual transient modulation of the relaxation rates of excited photocarriers.
State-of-the-art calculations based on non-equilibrium Green’s functions provide a microscopic view onto the interplay of quasiparticle scattering and the transiently modified electronic band structure, highlighting the critical role of the phase space of electron-electron interaction. The results vividly demonstrate the possibility of controlling quasiparticle relaxation rates by transiently tuning the electronic band structure using light pulses.