Generally $\ce{H^+}$ ions in water remain in the form of hydronium ions ($\ce{H3O+}$), and not as "free" aqueous protons, as far as I've been taught.
My question: is this always the case, even when considering dynamics at extremely short time scales? By this I am not meaning interconversion with the Zundel ($\ce{H5O2+}$) or other states. I mean to say, does bare $\ce{H+}(\mathrm{aq})$ ever exist on, say, a femtosecond time scale?