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Water and ionic liquids: structure and relaxation
来源: 日期2017-09-22 15:31 点击:

讲座题目:Water and ionic liquids: structure and relaxation

讲座时间:925  10:10 am-11:10 am

讲座地点:基础学科大楼B 835

报告人:David L. Price

CEMHTI, CNRS, UPR 3079 and Université d'Orléans

(法国奥尔良大学极端条件材料研究所)

报告摘要:

The influence of water on the structure and relaxation of a prototype ionic liquid (IL) C8mimBF4 is examined in the IL-rich regime combining high-energy x-ray diffraction (HEXRD), quasi-elastic neutron scattering (QENS) and molecular dynamics (MD) simulations. The HEXRD and MD results show that the added water molecules occupy a diffuse coordination shell around the imidazolium ring but are not present around the alkyl tail. A complementary packing of water and imidazolium around BF4 was found, leading to surprisingly small differences in the average structure between the pure IL and the mixture.1 The QENS and MD simulations results for relaxation of the pure IL and the equimolar mixture with water probed by the dynamics of the C8mim hydrogen atoms in the time range of 2 ps to 1 ns are in excellent agreement. The QENS data show that translational relaxation increases by a factor of 7 on the addition of water, while rotational relaxation involving multiple processes fitted by a KWW function with low β values is speeded up by a factor of 3 on the time scale of the QENS measurements. The MD simulations show that the cation diffusion coefficient, inverse viscosity, and ionic conductivity increase on the addition of water, consistent with the very small change in ionicity. Difficulties in obtaining rotational and translational diffusion coefficients from fits to QENS experiments of ILs will be discussed.2

1. D. L. Price, et.al. Effect of Water on the Structure of a Prototype Ionic Liquid, Phys. Chem. Chem. Phys. 2016, 18, 23474 ;

2. D. L. Price, et.al. Relaxation in a Prototype Ionic Liquid: Influence of Water on the Dynamics, J. Phys. Chem. Lett. 2017, 8, 715

个人简介:

U. S. Department of Energy, Washington, D.C.

2011-2012  Program Officer for Neutron Facilities, Scientific User Facilities Division

Oak Ridge National Laboratory

2004-2005  Executive Director, High Flux Isotope Reactor and Center for Neutron Scattering Research Center for Materials at High Temperature, Orléans, France

2001-present Researcher

Argonne National Laboratory

1989-2001  Distinguished Senior Physicist

1979-1981  Director, Intense Pulsed Neutron Source

1976-1989  Senior Physicist

1974-1979  Director, Solid State Science Division

1971-1976  Physicist

1968-1971  Assistant Physicist

Brookhaven National Laboratory

1966-1968  Research Associate

PROFESSIONAL SOCIETIES:

Neutron Scattering Society of America (Fellow), American Physical Society (Fellow), Institute of Physics, UK (Fellow)

 
 
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责任编辑:杨欣玥
 
 
 
 
 
 
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