Modelling photoelectron spectra in solution: adenosine as a test case

We here describe a procedure for the calculation of photoelectron spectra in solution, including vibrational and dynamical solvent effect. Steady state vibronic spectra are computed in harmonic approximation including the effect of the electronic continuum on the computation of the cross section. Solvent effect are described in the framework of continuum solvation model, providing an accurate assessment of dynamical solvation effects, crucial for a reliable modeling of photoelectron processes, with a very small computational cost. Time-resolved photoelectron spectra are computed from the nonadiabatic quantum dynamics of the electronic-vibrational wavepacket propagating on the coupled valence states, described with a linear vibronic coupling model, within a short-time semiclassical approximation. Our approach provides accurate steady state photoelectron spectra for 9(H)adenine in the gas phase and adenosine in water. In the former case, the position, the relative energy and the dependence on the photoelectron ejection angle for the three lowest energy bands are in good agreement with the experimental ones. We simulated the pump-probe photoelectron spectrum of adenosine in water by both static and dynamical approach obtaining spectra fully consistent with the experimental ones, getting new insights on its sub-ps photophysics. Some methodological issues on the simulation of photoelectron spectra in solutions are also discussed.