8th Liquid Matter Conference September 6-10, 2011 Wien, Austria ...

Thu 811:10-14:00P8.29Influence of pores on the polyamorphic transition inwaterChristian Mitterdorfer, 1 Michael S. Elsaesser, 1 Katrin Winkel, 1 Erwin Mayer, 2 andThomas Loerting 11 Institute of Physical Chemistry, Innrain 52a, 6020, Innsbruck, Austria2 Institute of General, Inorganic and Theoretical Chemistry, Innsbruck, AustriaWe study the pressure-induced polyamorphic transition from low-density to high-density amorphousice at 77K in a piston cylinder apparatus. [1] Three different types of sample are employedfor the study, namely amorphous solid water (ASW), hyperquenched glassy water (HGW) andlow-density amorphous ice (LDA). ASW is produced by water vapour deposition and is a highlymicroporous solid capable of adsorbing huge amounts of small molecules such as nitrogen. Thesemicropores can be removed by annealing the sample at ∼130K. HGW is produced by ultrafast(> 107 K/s) cooling of micron-sized water droplets. The droplet structure is retained in the glassystate, and large empty voids are found between single droplets. These voids are retained even afterannealing. LDA is produced from hexagonal ice by pressure-induced amorphization followedby a decompression step. This sample is practically free of pores and voids. Despite the verydifferent preparation procedure all three samples are identical in terms of molecular structure.[2] By comparing the compression behaviour and the sharpness of the transition to high-densityamorphous ice at 0.7 GPa between the three samples we reveal the influence of pores and poresizes on the polyamorphic transition.[1] T. Loerting et al. , Phys. Chem. Chem. Phys. , 2011, 13, 8783-8794[2] D. T. Bowron et al. , J. Chem. Phys. , 2006, 125, 19450229