Spotlights: Volume 8, Issue 14 - The Journal of Physical Chemistry

Jul 20, 2017 - Amaya, Pathak, Modak, Laksmono, Loh, Sellberg, Sierra, McQueen, Hayes, Williams, Messerschmidt, Boutet, Bogan, Nilsson, Stan, and ...
0 downloads 0 Views 128KB Size
Spotlights pubs.acs.org/JPCL

Spotlights: Volume 8, Issue 14





HOW CUBIC CAN ICE BE? Most people will admit that the ice cubes floating in their lemonade are not perfect cubes, but they probably do not know that perfectly cubic ice cannot be achieved today. Water molecules usually freeze with hexagonal symmetry, leading to unevenly shaped ice in our freezers and our ponds. This may seem inconsequential (after all, the lemonade is chilled no matter the ice’s shape), but weather and climate change scientists would disagree. Recent evidence suggests that cubicor nearly cubicice exists in Earth’s atmosphere, where clouds are formed by supercooled water droplets. Previous experiments using micron-sized water droplets have led to ice that is approximately 70% cubic, and Amaya et al. (10.1021/acs.jpclett.7b01142) set out to determine whether a higher cubicity value, χ, could be achieved in the laboratory. They conducted freezing experiments in nanodroplets produced in a supersonic nozzle, where freezing starts at ∼225 K. They then used an X-ray free-electron laser to measure the diffraction spectra of the ice