Studies of liquid-liquid phase transition and critical phenomena in supercooled confined water by neutron scattering

Small angle neutron scattering (SANS) is used to measure the density of water contained in 1-D cylindrical pores of a mesoporous silica material MCM-41-S. By being able to suppress the homogenous nucleation process inside the narrow pore, one can keep water in the liquid state down to at least 160 K. We observe a density minimum at 210±5 K. This is the first experimental evidence of the existence of the density minimum in supercooled water. We show that the results are consistent with the predictions of molecular dynamics simulations of supercooled bulk water. From a combined analysis of SANS data from both H20 and D20 hydrated samples, we determined the absolute value of the density of water in the 1-D confined geometry. We found that the average density of water inside the fully hydrated MCM-41-S is higher than that of the bulk water. Pore size and hydration level dependences of the density are also studied. The temperature derivative of the density shows a pronounced peak signaling the crossing of the Widom line and confirming the existence of a liquid-liquid critical point at an elevated pressure.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Nuclear Science and Engineering.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2008

Author dc:creator

• Liu, Dazhi, Ph. D. Massachusetts Institute of Technology

Advisor dc:contributor.advisor

• Sow-Hsin Chen.

• Nuclear Science and Engineering.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/53260

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/53260