应浙江大学联合化学反应工程研究所邀请，德国伊尔默瑙大学高分子物理系教授Prof. Siegfried Stapf 将于2007年10月26日至31日来我院进行学术访问，并定于2007年10月29日（周一）上午9点在玉泉校区教10－4115进行学术报告。
报告题目：Field Cycling NMR Relaxometry - Tutorial and Polymer Investigations
报告人： Prof. Siegfried Stapf
报告时间：2007年10月29日（周一）上午9：00－11：00
报告地点：教10－4115
Abstract：Molecular dynamics in natural and artificial systems often take place over a wide range of frequencies, and a complete description can only be achieved by experimental techniques that are able to measure quantities in a time or frequency dependent manner. The dynamics of macromolecules such as polymer melts, gels or rubbery materials, is one particularly prominent example where motion occurs over many orders of magnitude in timescale. “Classical” methods such as mechanical deformation monitor the macroscopic behaviour of the material as a function of a frequency-dependent excitation. The microscopic cause of these processes can be elucidated by techniques measuring parameters that are sensitive to molecular motion, such as the NMR relaxation time. However, in the case of T1 relaxation, those motions are most efficient that occur on a timescale corresponding to the inverse Larmor frequency at the given magnetic field strength; in order to scan a wide portion of the spectrum of molecular motions covering many orders of magnitude, measurements need to be carried out at different field strengths.
This lecture will present the strategies of generating variable magnetic fields, focusing on the most widely used approach of electronic field switching. The differences between field-cycling and conventional high- and low-field NMR will be highlighted and limitations will be discussed. The theory of frequency-dependent relaxation will be treated by discussing simple examples and some important applications. In the second part of the talk, case studies of molecular dynamics in various systems, with a focus on polymers and elastomers, will be presented in order to demonstrate the wide range of areas where field cycling relaxometry can be employed to provide information not accessible by conventional or other NMR techniques.
Prof. Siegfried Stapf简介：
Prof. Siegfried Stapf 1996年获得University of Ulm（Germany）博士学位，1997年至1999年在University of Nottingham从事博士后研究，1999年至2004年在RWTH Aachen University 做Habilitation，2007年起被聘为TU Ilmenau (Germany)高分子物理系教授。Prof. Siegfried Stapf的研究领域主要集中于核磁共振技术在化学工程以及高分子材料中的应用，所涉及的研究方向有：受限条件下液体以及高聚物熔体的弛豫和扩散；多孔介质中流体流动的NMR表征；多维NMR方法测定反应介质的流形和速度分布；场循环技术对聚合物熔体链段动力学的研究。
材料与化工学院
2007年10月26日
