Observation of the density minimum in deeply supercooled confined water
- *Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139;
- †Department of Chemistry, National Taiwan University, Taipei 106, Taiwan; and
- ‡Department of Physics, St. Francis Xavier University, Antigonish, NS, Canada B2G 2W5
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Edited by H. Eugene Stanley, Boston University, Boston, MA, and approved April 16, 2007 (received for review February 13, 2007)
Abstract
Small angle neutron scattering (SANS) is used to measure the density of heavy water contained in 1D cylindrical pores of mesoporous silica material MCM-41-S-15, with pores of diameter of 15 ± 1 Å. In these pores the homogenous nucleation process of bulk water at 235 K does not occur, and the liquid can be supercooled down to at least 160 K. The analysis of SANS data allows us to determine the absolute value of the density of D2O as a function of temperature. We observe a density minimum at 210 ± 5 K with a value of 1.041 ± 0.003 g/cm3. We show that the results are consistent with the predictions of molecular dynamics simulations of supercooled bulk water. Here we present an experimental report of the existence of the density minimum in supercooled water, which has not been described previously.
Footnotes
- §To whom correspondence should be addressed. E-mail: sowhsin{at}mit.edu
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Author contributions: S.-H.C. designed research; D.L. and Y.Z. performed research; D.L., C.-C.C., C.-Y.M., and S.-H.C. contributed new reagents/analytic tools; D.L. analyzed data; and D.L., Y.Z., C.-Y.M., P.H.P., and S.-H.C. wrote the paper.
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The authors declare no conflict of interest.
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This article is a PNAS Direct Submission.
- Abbreviations:
- LDA,
- low density amorphous;
- LLPT,
- liquid–liquid phase transition;
- MD,
- molecular dynamics;
- SANS,
- small angle neutron scattering;
- sld,
- scattering length density;
- TIP5P,
- five-site transferable interaction potential.
- © 2007 by The National Academy of Sciences of the USA
