Infrared Spectroscopic Evidence for Protonated Water Clusters Forming Nanoscale Cages.

Size-dependent development of the hydrogen bond network structure in largesized clusters of protonated water, H+(H2O)n (n = 4 to 27), was probed by infrared spectroscopy of OH stretches. Spectral changes with cluster size demonstrate that the chain structures at small sizes (n ≲ 10) develop into two-dimensional net structures (∼10