第24讲-高阶效应、动力学和核磁共振时间标度Lecture 24 - Higher-Order Effects, Dynamics, and the NMR Time Scale |
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课程网址: | http://videolectures.net/yalespan125bs2011_mcbride_lec24/ |
主讲教师: | J. Michael McBride |
开课单位: | 耶鲁大学 |
开课时间: | 2014-08-19 |
课程语种: | 英语 |
中文简介: | 因为自旋分裂依赖于原子核上的电子自旋,所以C-13的分裂依赖于它的轨道杂化。对于具有类似化学位移的原子核,给出复杂多重态的“高阶效应”可以用类似能量波函数的混合来理解。化学位移或自旋分裂的平均值可用于测量分子结构的快速变化速率,例如构象或氢键的变化。由于光谱的时间尺度取决于频率差,因此NMR中的平均比IR中的平均更容易。一个典型的问题是预测含有非对映基团的化合物的核磁共振谱。在质子去耦中,特定质子的射频辐照可以使其停止从附近质子分裂核磁共振信号。 |
课程简介: | Because spin-spin splitting depends on electron spin precisely at a nucleus, splitting by a C-13 depends on its orbital’s hybridization. "Higher-order effects" that give complex multiplets for nuclei with similar chemical shifts can be understood in terms of the mixing of wave functions of similar energy. Averaging of chemical shifts or spin-spin splitting may be used to measure the rate of rapid changes in molecular structure, such as changes in conformation or hydrogen bonding. Since the spectroscopic time scale depends on frequency differences, averaging is easier in NMR than in IR. A typical problem involves predicting the NMR spectrum of a compound with diastereotopic groups. In proton decoupling radio frequency irradiation of a particular proton can make it cease to split the NMR signals from nearby protons. |
关 键 词: | 高阶效应; 核磁共振; 轨道杂化 |
课程来源: | 视频讲座网 |
数据采集: | 2021-11-18:zkj |
最后编审: | 2021-11-18:zkj |
阅读次数: | 73 |