A. General considerations Photoelectron spectroscopy (PES) studies from liquids and particularly from water and aqueous solutions, mostly in conjunction with a liquid microjet,1,21. B. Winter and M. Faubel, Chem. Rev. 106(4), 1176 (2006). https://doi.org/10.1021/cr040381p2. R. Dupuy, C. Richter, B. Winter, G. Meijer, R. Schlögl, and H. Bluhm, J. Chem. Phys. 154(6), 060901 (2021). https://doi.org/10.1063/5.0036178 have contributed tremendously to our current understanding of the aqueous-phase electronic structure.