2026-09-20T12:26:38Zhttps://dspace.mit.edu/server/oai/requestoai:dspace.mit.edu:1721.1/532602022-01-13T07:54:37Zcom_1721.1_7582com_1721.1_7581col_1721.1_131022
Sow-Hsin Chen.
Liu, Dazhi, Ph. D. Massachusetts Institute of Technology
Massachusetts Institute of Technology. Dept. of Nuclear Science and Engineering.
Massachusetts Institute of Technology. Department of Nuclear Science and Engineering
2010-03-25T15:22:27Z
2010-03-25T15:22:27Z
2008
2008
http://hdl.handle.net/1721.1/53260
540802176
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Nuclear Science and Engineering, 2008.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 69-72).
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.
by Dazhi Liu.
Ph.D.
72 p.
eng
Massachusetts Institute of Technology
M.I.T. theses are protected by
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http://dspace.mit.edu/handle/1721.1/7582
Nuclear Science and Engineering.
Studies of liquid-liquid phase transition and critical phenomena in supercooled confined water by neutron scattering
Thesis
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<Abstract>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.</Abstract>
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