From PNNL Lab: “Watching Molecules in Slow Motion”
Pacific Northwest National Laboratory (PNNL)
By supercooling liquids, scientists can determine the physics happening in glasses
June 2012
No Writer Credit
Results: The whereabouts of exceedingly slow-moving molecules in glasses can be quickly and efficiently measured, thanks to a new technique that uses vapor and extreme cold to drop the molecules’ speed a trillion times. Designed by Dr. Scott Smith and Dr. Bruce Kay at Pacific Northwest National Laboratory, the method supercools vapor molecules turning them into a glassy film. Then, they heat the film just enough to get the molecules moving at the desired speed to study. An overview of this new method appears in an invited Perspective article in Journal of Physical Chemistry Letters.
Why It Matters: While glass is ubiquitous in the world today, from fiber optic cables to fuel cells to pharmaceuticals, and even nuclear waste storage, fundamental glass properties are not clearly understood. Knowledge gaps exist, in part, because supercooling alcohols, water and other small molecular liquids was not easy. This difficulty meant that fundamental questions were the purview of computer simulations and models. With this new technique, scientists can get precise data. The data will answer basic questions, and one day may guide transformations into key industries.
As liquids cool, they can take on different states depending on various conditions. A liquid can cool to become a supercooled liquid and then a glass, given the right conditions. The more common route is for the liquid to cool into a crystalline solid. (No image credit)
From fiber optic cables to fuel cells, and even nuclear waste storage, glass is pervasive in today’s world; however, the fundamental properties of glass are not clearly understood.
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