Three-dimensional infrared spectroscopy of isotope-substituted liquid water reveals heterogeneous dynamics

J Phys Chem B. 2011 Jun 2;115(21):6976-84. doi: 10.1021/jp201989s. Epub 2011 May 11.

Abstract

The dynamics of the hydrogen bond network of isotopically substituted liquid water are investigated with a new ultrafast nonlinear vibrational spectroscopy, three-dimensional infrared spectroscopy (3D-IR). The 3D-IR spectroscopy is sensitive to three-point frequency fluctuation correlation functions, and the measurements reveal heterogeneous structural relaxation dynamics. We interpret these results as subensembles of water which do not interconvert on a half picosecond time scale. We connect the experimental results to molecular dynamics (MD) simulations, performing a line shape analysis as well as complex network analysis.