We study the vibrational dynamics of nanodroplets of liquid water with femtosecond two-color midinfrared pump-probe spectroscopy. For the smallest nanodroplet, containing 10-15 water molecules, the lifetime T1 of the O-H stretch vibrations is equal to 0.85±0.1 ps, which is more than 3 times as long as in bulk liquid water. We find that the truncation of the hydrogen-bond network of water leads to a dramatic change of the relaxation mechanism.

Phys. Rev. Lett.
Ultrafast Spectroscopy

Dokter, A.M, Woutersen, S, & Bakker, H.J. (2005). Anomalous slowing down of the vibrational relaxation of liquid water upon nanoscale confinement. Phys.Rev.Lett., 94(Article number: 178301), 1–4. doi:10.1103/physrevlett.94.178301