Experiments carried out by scientists in the US have provided new evidence in the controversial issue of surface freezing in alkane nanodroplets.
For small droplets, or systems with free surfaces, such as those in atmospheric aerosols, the freezing mechanism of hydrocarbons is a highly debated topic. Until now, experimental techniques have not been able to distinguish between surface and volume freezing.
Barbara Wyslouzil and colleagues at the Ohio State University, Columbus, are interested in understanding phase transitions and organization in nanodroplets. ‘Since surface-to-volume ratio increases as objects get smaller, nanodroplets present an obvious advantage for the study of surface effects,’ says Wyslouzil. Nanodroplets of n-octane and n-nonane were formed and rapidly cooled in a continuous flow supersonic Laval nozzle. As the condensable carrier gas mixture flows through the nozzle, the flow accelerates, effectively cooling as the pressure and temperature drop. This first condenses the vapour to liquid droplets, then freezes them.
Read the full article in Chemistry World here…
Read this article in PCCP:
Experimental evidence for surface freezing in supercooled n-alkane nanodroplets
Viraj P. Modak, Harshad Pathak, Mitchell Thayer, Sherwin J. Singer and Barbara E. Wyslouzil
DOI: 10.1039/C3CP44490B
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