Freezing-memory effect of water on nucleation of CO2 hydrate crystals

We measured the times to nucleate CO2 hydrates from CO2 dissolved water und er pressure and 8.6 K supercooling using different methods to prepare the w ater. These times ranged from 50 min to more than 7200 min, depending on th e preparation method. The nucleation rates were calculated by fitting the o bserved nucleation probability distributions to a nucleation rate equation. The nucleation rates significantly increased when the water had previously frozen as ice and melted (freezing-memory effect), except when the meltwat er was heated to 298 K before nucleation. The nucleation rates also increas ed with O-2-saturated meltwater, but decreased with degassed water.