We report on the observation of a strong reorganization of the proton hydration structure in hydrated Nafion membranes following single-quantum excitation of a proton vibration with ∼4 μm light pulses. The reorganization takes place with a time constant of 170±20  fs and leads to a strong red shift of the excited proton vibration and the rise of new waterlike O–H stretch absorption bands. These observations can be explained from a vibrational-excitation-induced change of the proton-hydration structure that involves transfer of the proton charge. The results are consistent with recent quantum molecular dynamics simulations of proton transfer in Nafion membranes.

APS
dx.doi.org/10.1103/PhysRevLett.112.258301
Phys. Rev. Lett.
Ultrafast Spectroscopy

Liu, L, & Bakker, H.J. (2014). Infrared-activated proton transfer in aqueous Nafion proton-exchange-membrane nanochannels. Phys.Rev.Lett., 112(Article number: 258301), 1–5. doi:10.1103/PhysRevLett.112.258301