Fast Scanning Calorimetry Studies of Amorphous Solid Water
When
Dec 5, 2008 4:00 pm - 5:00 pm (Friday)
What
By: Chemistry, Department of
Cost: Free Location: Corcoran 101 The fast scanning calorimetry (FSC) apparatus was employed to investigate glass transition phenomena in vapor deposi...
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Event details: Fast Scanning Calorimetry Studies of Amorphous Solid Water
Description
By: Chemistry, Department of
Cost: Free
Location: Corcoran 101
The fast scanning calorimetry (FSC) apparatus was employed to investigate glass transition phenomena in vapor deposited amorphous solid water (ASW) films doped with acetic acid, pentanol, and carbon tetrachloride. In all three cases, FSC thermograms of doped ASW films show well pronounced glass transitions at temperatures near 177 K. Systematic FSC measurements of the glass transition temperature and the excess heat capacity dependence on the concentration of impurities indicate the possible existence of two distinct non-crystalline phases of H2O in binary aqueous solutions. According to our conjecture, bulk pure ASW is a glass at temperatures up to its crystallization at temperatures near 205 K. However, a guest molecule in the ASW matrix may be enveloped in ultraviscous liquid water at temperatures as low as 136 K. In the case of CH3COOH, we estimate that such a viscous shell contains approximately 25 H2O molecules. This seminar will discuss the implications of these findings for past studies of molecular kinetics in pure vitreous water and in binary aqueous solutions.
Cost: Free
Location: Corcoran 101
The fast scanning calorimetry (FSC) apparatus was employed to investigate glass transition phenomena in vapor deposited amorphous solid water (ASW) films doped with acetic acid, pentanol, and carbon tetrachloride. In all three cases, FSC thermograms of doped ASW films show well pronounced glass transitions at temperatures near 177 K. Systematic FSC measurements of the glass transition temperature and the excess heat capacity dependence on the concentration of impurities indicate the possible existence of two distinct non-crystalline phases of H2O in binary aqueous solutions. According to our conjecture, bulk pure ASW is a glass at temperatures up to its crystallization at temperatures near 205 K. However, a guest molecule in the ASW matrix may be enveloped in ultraviscous liquid water at temperatures as low as 136 K. In the case of CH3COOH, we estimate that such a viscous shell contains approximately 25 H2O molecules. This seminar will discuss the implications of these findings for past studies of molecular kinetics in pure vitreous water and in binary aqueous solutions.
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The George Washington University
The George Washington University (GWU) is a private, coeducational, non-sectarian university located in Washington, D.C.. Founded in 1821 as The Columbian College on land provided by former President George Washington, the university has since developed into a leading educational and research institution. The 43 acre campus, located in the city's historic Foggy Bottom neighborhood, is situated a few blocks from the White House and the rest of the National Mall. In 1999, the university acquired the Mount Vernon College for Women. As of 2006, the George Washington University's endowment and other trust funds total approximately $1.017 billion. George Washington is currently ranked 52nd on U.S. News & World Report's list of Top National Universities. In addition to 4,500 staff members, The George Washington University enrolls an even balance of undergraduate and graduate students; roughly 11,000 of the former and 12,500 of the latter.Post a Countdown Widget
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