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The Statesman

The Student News Site of Stony Brook University

The Statesman

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    STONY BROOK GRADUATE RESEARCHES AT HIGH PRESSURE

    The 2002 Alvin Van Valkenburg Award has been given to Yongjae Lee, a postdoctoralfellow in the Physics Department of Energy’#146;s Brookhaven National Laboratoryfor advancing the research on a recently discovered group of materials thatexpand under pressure.

    The award is given every other year in honor of Alvin Van Valkenburg, co-inventorof the diamond anvil cell, to celebrate a young scientist who uses this innovationin his research.

    Lee was presented the award and discussed his work on June 26, 2002, at a ceremonyduring the Gordon Conference on ‘Research at High Pressure’ in NewHampshire. He dedicated the award to his wife and newborn son.

    ‘I am very honored to win this international young scientist award inhigh pressure sciences,’ Lee said. ‘Most of the discoveries and resultswould not have been possible without support and creative input from my manymentors and collaborators, and the optimal instrumentation available at BrookhavenLab.’

    The subject of Lee’#146;s research was the pressure-generated swelling of zeolites,which was uncovered by an international collaboration between Brookhaven Laband the School of Chemical Sciences at England’#146;s University of Birmingham.These zeolites are placed in a diamond anvil cell and high pressure is appliedcausing the surrounding fluid to pack into its small pores. These results couldprove to be advantageous when the zeolite is used as a sponge to absorb chemicalpollutants or radioactive wastes, trapping the fluid and larger molecules insideas the material contracts when pressure is released.

    Lee and his colleagues used the technique of ‘powder diffraction’at Brookhaven’#146; National Synchrotron Light Source, to determine the breakdownof the zeolite’#146;s molecular structure. Their results, published in the Journalof the American Chemical Society, explain the zeolite’#146;s unusual abilityto soak up excess fluid and show where the extra liquid goes.

    In a diamond anvil cell, the material was subjected to 50,000 times the normalatmospheric pressure. The zeolite was packed between two diamonds, the hardestsubstance on Earth, in a small cavity filled with liquid, which helped spreadthe pressure uniformly to all sides. A concentrated beam of x-ray inundatedthe sample while scientists examined how the beams diffracted as they hit thezeolite and bounced off.

    The diffraction arrangement was then translated onto a computer in order tocreate a three-dimensional molecular structure.

    At first the material appeared to contract as expected. However, as the pressurereached between 8,000 to 15,000 times the normal atmospheric pressure, the zeoliteexpanded along two of its three dimensions. Further study of the molecular structureshowed that during the expansion, superfluous liquid molecules squeezed intothe pores of the zeolite, making it into a ‘superhydrated’ zeolite.

    Lee received a master’#146;s degree in geosciences from Stony Brook Universityin 1988, and a bachelor’#146;s degree in earth system sciences from Yonsei Universityin Seoul, Korea in 1996. After completing his doctoral studies in geosciencesat Stony Brook, he came to Brookhaven Laboratory in 2001 as a postdoctoral fellowin the powder diffraction group. The U.S. Department of Energy, which supportsresearch in a range of scientific disciplines, funded Lee’#146;s research.

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