Nucleation of pure and AgI seeded supercooled water using an Automated Lag Time Apparatus

Heneghan, Aaron; Haymet, A. D. J.
August 2000
AIP Conference Proceedings;2000, Vol. 534 Issue 1, p439
Academic Journal
The evolution of non-equilibrium systems into equilibrium has been studied for many years. However, there is still a need for a unified theory which describes this evolution in time. It is known that all systems reach equilibrium eventually, but difficulties arise in determining how long eventually is. The Automatic Lag Time Apparatus(ALTA) was constructed to collect statistics of nucleation on a single sample. The ergodic hypothesis states that the time average is equal to the ensemble average. Hence, running one sample 500 times is equivalent to trying to prepare and monitor 500 identical samples. ALTA repeatedly supercools a sample to a set supercooling point, measures the time until nucleation, heats the sample for four minutes to ensure all of the ice crystals have melted, and repeats the above steps as many times as possible in order to gain statistics of nucleation. By analyzing these statistics of nucleation, various theories of nucleation can be tested.


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