TY - JOUR
T1 - The dynamic response function χT(Q,t) of confined supercooled water and its relation to the dynamic crossover phenomenon
AU - Chen, Sow Hsin
AU - Zhang, Yang
AU - Lagi, Marco
AU - Chu, Xiangqiang
AU - Liu, Li
AU - Faraone, Antonio
AU - Fratini, Emiliano
AU - Baglioni, Piero
N1 - Funding Information:
Research at MIT is supported by DE-FG02–90ER45429; at University of Florence by MIUR and CSGI. The authors are grateful to J. Copley, V. Garcia-Sakai and E. Mamontov for assistance with the data collection on DCS and HFBS at NIST and BASIS at SNS. We are also indebted to A. Kolesnikov for preparing the DWNT sample. Identification of a commercial product does not imply recommendation or endorsement by the National Institute of Standards and Technology, nor does it imply that the product is necessarily the best for the stated purpose. We thank SNS in ORNL sponsored by the Scientific User Facilities Division, Office of Basic Energy Sciences, U. S. Department of Energy. Dry
PY - 2010
Y1 - 2010
N2 - We have made a series of Quasi-Elastic Neutron Scattering (QENS) studies of supercooled water confined in 3-D and 1-D geometries, specifically, interstitial water in aged cement paste (3-D) and water confined in MCM-41-S and Double Wall Nano Tube DWNT (l-D). In addition, we also include the cases of hydration water on protein surface and other biopolymer surfaces (pseudo 2-D). By analyzing the QENS spectra using Relaxing Cage Model (RCM), we are able to extract accurately the self-intermediate scattering function of hydrogen atoms FH(Q,t), at low-Q as a function of temperature T, showing an α-relaxation process at long time. We can then construct the Dynamic Response Function χT(Q,t) = -dFH(Q,t)/dT. χT(Q,t) as a function of t at constant Q shows a single peak at the characteristic α-relaxation time (τ), the amplitude of which grows as we approach the dynamic crossover temperature TL observed before in each of these geometries. However, the peak height of χT(Q,t) decreases after passing the crossover temperature TL. We make an argument to relate the occurrence of the extremum of the peak height in χT to the existence of the dynamic crossover temperature in each of these cases.
AB - We have made a series of Quasi-Elastic Neutron Scattering (QENS) studies of supercooled water confined in 3-D and 1-D geometries, specifically, interstitial water in aged cement paste (3-D) and water confined in MCM-41-S and Double Wall Nano Tube DWNT (l-D). In addition, we also include the cases of hydration water on protein surface and other biopolymer surfaces (pseudo 2-D). By analyzing the QENS spectra using Relaxing Cage Model (RCM), we are able to extract accurately the self-intermediate scattering function of hydrogen atoms FH(Q,t), at low-Q as a function of temperature T, showing an α-relaxation process at long time. We can then construct the Dynamic Response Function χT(Q,t) = -dFH(Q,t)/dT. χT(Q,t) as a function of t at constant Q shows a single peak at the characteristic α-relaxation time (τ), the amplitude of which grows as we approach the dynamic crossover temperature TL observed before in each of these geometries. However, the peak height of χT(Q,t) decreases after passing the crossover temperature TL. We make an argument to relate the occurrence of the extremum of the peak height in χT to the existence of the dynamic crossover temperature in each of these cases.
KW - Confined supercooled water
KW - Dynamic crossover phenomenon
KW - Dynamic response function
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U2 - 10.1524/zpch.2010.6095
DO - 10.1524/zpch.2010.6095
M3 - Short survey
AN - SCOPUS:77649246883
VL - 224
SP - 109
EP - 131
JO - Zeitschrift fur Physikalische Chemie
JF - Zeitschrift fur Physikalische Chemie
SN - 0942-9352
IS - 1-2
ER -