Density Measurement of 1-D Confined Water by Small Angle Neutron Scattering Method: Pore Size and Hydration Level Dependences

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• 作者：Dazhi Liu ; Yang Zhang ; Yun Liu ; Jianlan Wu ; Chia-Cheng Chen ; Chung-Yuan Mou ; Sow-Hsin Chen
• 刊名：Journal of Physical Chemistry B
• 出版年：2008
• 出版时间：April 10, 2008
• 年：2008
• 卷：112
• 期：14
• 页码：4309 - 4312
• 全文大小：100K
• 年卷期：v.112,no.14(April 10, 2008)
• ISSN：1520-5207

文摘

Small angle neutron scattering (SANS) is used to measure the absolute density of water contained in 1-Dcylindrical pores of a silica material MCM-41-S with pore diameters of 19 and 15 Å. By being able to suppressthe homogeneous nucleation process inside the narrow pore, one can keep water in the liquid state down toat least 160 K. From a combined analysis of SANS data from both H₂O and D₂O hydrated samples, wedetermined the absolute value of the density of 1-D confined water. We found that the average density ofwater inside the fully hydrated 19 Å pore is 8% higher than that of the bulk water at room temperature. Thetemperature derivative of the density shows a pronounced peak at T_L = 235 K signaling the crossing of theWidom line at ambient pressure and confirming the existence of a liquid-liquid phase transition at an elevatedpressure. Pore size and hydration level dependences of the density are also studied.