- PDF 免费下载

Size: px

Start display at page:

Download ""

澜越眺璩
5 years ago
Views:

1 学校编码 :10384 分类号密级学号 :B UDC 厦门大学博士学位论文液体核磁共振中分子间多量子相干及其应用 Intermolecular Multiple-Quantum Coherences in Liquid NMR and Their Applications 陈志伟指导教师姓名 : 陈忠教授吴钦义教授专业名称 : 物理化学论文提交日期 :2004 年 11 月论文答辩时间 :2004 年 12 月学位授予日期 : 答辩委员会主席 : 评阅人 : 2004 年 11 月

3 厦门大学学位论文原创性声明兹呈交的学位论文, 是本人在导师指导下独立完成的研究成果本人在论文写作中参考的其他个人或集体的研究成果, 均在文中以明确方式标明本人依法享有和承担由此论文而产生的权利和责任声明人 ( 签名 ): 2004 年 11 月 20 日

5 目录中文摘要 i 英文摘要 iii 第一章绪论分子间多量子相干现象分子间多量子相干的理论描述 CRAZED 脉冲序列经典理论描述偶极场方法量子理论描述分子间多量子相干方法量子 - 经典理论描述分子间多量子相干研究进展分子间多量子相干的应用在微观结构测量方面的应用在磁共振成像和功能磁共振成像方面的应用不均匀场下的高分辨率谱论文结构 29 第二章分子间多量子相干纵向弛豫过程的定量研究引言原理和方法实验结果与讨论本章小结 46 第三章双组分体系分子间偶极相互作用的定量表征引言原理和方法 50

6 3.3 实验结果与讨论实验 I 自旋的信号特性自旋 S 的信号特性本章小结 66 第四章分子间单量子相干的机理和性质研究引言原理和方法实验结果与讨论实验远程偶极相互作用的验证不同相干阶的信号强度比较优化射频射频脉冲翻转角弛豫和扩散性质二维脉冲梯度场 COSY 谱的额外交叉峰本章小结 86 第五章三自旋阶分子间多量子相干信号的分离和表征引言原理和方法偶极场方法分子间多量子相干方法实验结果与讨论实验不同相干阶的信号强度比较优化射频脉冲翻转角纵向弛豫时间 102

7 5.3.5 扩散本章小结 105 第六章不均匀磁场中获得高分辨率 NMR 谱的分子间多量子相干方法引言分子间零量子相干 HOMOGENIZED 方法的改进 SEL-HOMOGENIZED 脉冲序列分析实验结果与讨论基于分子间双量子和单量子相干的方法基于分子间双量子相干的 IDEAL 方法基于分子间双量子相干的 IDEAL-II 方法基于分子间单量子相干的 IDEAL-III 方法本章小结 131 第七章全文总结与展望全文总结展望 137 获奖和论文发表情况 141 致谢 147

8 CONTENTS Abstract in Chinese i Abstract in English iii Chapter 1 Preface Phenomena of intermolecular multiple-quantum coherences Theoretical treatments of intermolecular multiple-quantum coherences CRAZED pulse sequence Classical treatment dipolar field Quantum treatment intermolecular multiple-quantum coherences Quantum-classical treatment Recent progress in intermolecular multiple-quantum coherences Applications of intermolecular multiple-quantum coherences Exploration of microstructures MRI and fmri High-resolution spectra in inhomogeneous fields Structure of this dissertation 29 Chapter 2 Quantitative study of longitudinal relaxation time related to intermolecular multiple-quantum coherences Introduction Theoretical formalism and method Experimental results and discussion Conclusions 46

9 Chapter 3 Quantitative characterization of intermolecular dipolar interactions of two-component systems Introduction Theoretical formalism and method Experimental results and discussion Experiments Features of NMR signals of I spin Features of NMR signals of S spin Conclusions 66 Chapter 4 Observation and characterization of intermolecular homonuclear single-quantum coherences Introduction Theoretical formalism and method Experimental results and discussion Experiments Validation of distant dipolar interactions Relative signal intensity of different coherence orders Optimal RF pulse flip angles Relaxation and diffusion properties Additional cross-peaks in 2D PFG COSY Conclusions 86 Chapter 5 Separation and characterization of different signals from intermolecular three-spin orders Introduction 91

10 5.2 Theoretical formalism and method Dipolar field treatment Intermolecular multiple-quantum coherence treatment Experimental results and discussion Experiments Relative signal intensity of different coherence orders Optimal RF pulse flip angles Longitudinal relaxation time Diffusion Conclusions 105 Chapter 6 High-resolution NMR spectra in inhomogeneous fields via intermolecular multiple-quantum coherences Introduction Improvement of HOMOGENIZED sequence SEL-HOMOGENIZED pulse sequence Experiments Results and discussion Based on intermolecular double- and single-quantum coherences IDEAL (Intermolecular double-quantum coherences) IDEAL-II (Intermolecular double-quantum coherences) IDEAL-III (Intermolecular single-quantum coherences) Conclusions 131 Chapter 7 Summary and prospect Summary Prospect 137

11 Awards and publications 141 Acknowledgements 147

13 作者姓名 : 陈志伟论文题目 : 液体核磁共振中分子间多量子相干及其应用作者简介 : 陈志伟, 男,1976 年 8 月出生,2000 年 9 月师从于厦门大学陈忠吴钦义教授, 于年月获博士学位中文摘要 1990 年当简单的 CRAZED 脉冲序列作用于简单的高极化核自旋体系时, 在一维实验时间域中发现了多自旋回波现象 (Multiple Spin Echo,MSE), 在二维实验频率域中发现了令人诧异的分子间多量子相干现象 (Intermolecular Multiple Quantum Coherence,iMQC), 这引起了核磁共振工作者极大的研究兴趣, 同时也给核磁共振界带来争论随着研究的深入, 理论和实验均表明这两种现象的本质是一样的, 都是由远程偶极相互作用引起的本论文采用经典的偶极场和量子力学的密度矩阵理论方法, 并利用脉冲梯度场与选择激发相结合的实验手段, 对 imqc 的性质和机理进行了系统的研究, 还建立了利用 imqc 在不均匀场下获得高分辨率 NMR 谱的方法本论文主要研究成果有 : 一采用偶极场和量子力学积算符相结合的理论方法, 并利用脉冲梯度场与选择激发相结合的实验手段, 首次系统地定量研究了单组分单自旋和双组分双自旋体系的分子间多量子相干信号的相对强度优化脉冲翻转角扩散纵向弛豫和横向弛豫的性质二首次提出了分子间单量子相干 (isqc) 概念, 采用偶极场和 Torrey 方法相结合的有效方法对同核 isqc 进行了定量的研究, 利用选择激发技术首次从实验上分离出纯的二自旋阶 isqc 信号, 并对其信号强度优化脉冲翻转角扩散和弛豫等性质进行了定量表征, 为其在不均匀和不稳定磁场中获得高分辨率 NMR 谱奠定了坚实的理论和实验基础 i

14 三在国际上首次成功分离出来自纵向三自旋阶的分子间多量子相干信号, 并系统地分析和表征了其相对强度优化脉冲翻转角分子扩散和弛豫等特性四系统地提出了一系列基于分子间多量子相干的在不均匀磁场下获得高分辨率 NMR 谱的方法首先, 提出了改进的基于分子间零量子相干的 SEL-HOMOGENIZED 方法其次, 率先提出了基于分子间双量子相干的 IDEAL 和 IDEAL-II 方法以及基于分子间单量子相干的 IDEAL-III 方法这些方法可从不均匀磁场中获得常规高分辨率 NMR 谱所具有的化学位移 J 耦合常数多重峰结构信号强度等信息, 又各具特色优点, 可互为补充关键词 : 核磁共振 ; 分子间多量子相干 ; 高分辨率谱 ii

15 Intermolecular Multiple-Quantum Coherences in Liquid NMR and Their Applications Chen Zhiwei ABSTRACT Over the past decade or so, the multiple spin echo (MSE) or intermolecular multiple quantum coherence (imqc) phenomena in highly polarized nuclear spin systems have seemed to contradict conventional NMR theory and drawn great attention in NMR research community. In the subsequent deliberate research, these experimental phenomena were referred to be resulted from intermolecular dipole-dipole interaction. In this work, classical dipolar field theory and quantum-mechanical density matrix formalism were employed to analyze the coherences of spin dynamics. Techniques based on pulsed-field gradients and selective excitations were used to study the signals from imqcs. Several pulse sequences were designed to achieve 1D high-resolution NMR spectra in inhomogeneous fields. The main results are summarized as follows: 1. Liquid NMR behaviors related to intermolecular dipolar interactions were investigated theoretically and experimentally in highly polarized single-component and two-component spin systems. The properties of molecular diffusion, transverse relaxation, longitudinal relaxation, and optimal RF flip angles were quantitatively characterized. 2. For the first time, the concept of intermolecular single-quantum coherences (isqcs) was proposed. A combination of dipolar field treatment and Torrey equation was used to derive a general theoretical expression for the time evolution of spins with arbitrary flip angles of RF pulses. Signals from pure iii

16 homonuclear two-spin isqcs and intermolecular isqc cross peaks in homonuclear pulsed-field gradient COSY experiments were observed and characterized, in one- and two-dimensional experiments, respectively. 3. Signals originating from a pure specific coherence of intermolecular three-spin orders were separated and characterized experimentally in highly polarized two-component spin systems. For the first time, relaxation and diffusion properties of pure intermolecular single-, double-, and triple-quantum coherences of three-spin orders were characterized and analyzed in one-dimensional experiments. 4. Several pulse sequences based on the imqcs were proposed to obtain high-resolution 1D NMR spectra in inhomogeneous fields, including the SEL-HOMOGENIZED based on intermolecular zero-quantum coherences, IDEAL and IDEAL-II methods based on intermolecular double-quantum coherences, and IDEAL-III based on intermolecular single-quantum coherences. Chemical shifts, J couplings, multiplicity patterns, and relative areas are retained with these methods. Each method has its own advantages and plays a complementary role in different cases. Keywords: nuclear magnetic resonance; intermolecular multiple- quantum coherence; high-resolution spectra iv

17 Degree papers are in the Xiamen University Electronic Theses and Dissertations Database. Full texts are available in the following ways: 1. If your library is a CALIS member libraries, please log on and submit requests online, or consult the interlibrary loan department in your library. 2. For users of non-calis member libraries, please mail to etd@xmu.edu.cn for delivery details.

2

10384 -------- 9601008 UDC---------------------- 1999 1999 1999 ------------------------ ------------------------ 1 2 .4...4 7 14.14..18..22..22..24 3 4.27.32.39 1 2 3 4 5 6 7 8 9 10 11 5 12 6 1 2 3 4