Ice chains on copper are built from pentagons Available to Purchase

Before they form snowflakes and other familiar hexagonal crystals, water molecules nucleate in smaller configurations. Determining the structure of those precursors—even in the outwardly simple case of water on a clean metal surface—is an area of ongoing interest and controversy. Water forms different structures on different surfaces. For example, Andrew Hodgson and Sam Haq of the University of Liverpool in the UK noticed several years ago that when less than a single monolayer of water was adsorbed onto a copper (110) surface, vibrational spectra showed features characteristic of highly ordered, reduced-dimensional structures. They suspected that the water molecules were forming 1D chains, rather than 2D islands. Their hypothesis was confirmed by Hiroshi Okuyama and colleagues at Kyoto University in Japan, who obtained scanning tunneling microscopy images showing adsorbed water chains up to tens of nanometers in length but just 1 nm wide. ¹ But the STM images could not resolve...