小中大In quantum mechanics, the density matrix gives all possible information about a system. Operator formalisms are methods to act on the density matrix so as to give reasonable solutions to show the effect of a pulse and a delay in NMR.
在不考虑relaxation的情况下,简单说来,可以分成下面几部分来理解:
(1) 系统描述, 也就是说我们如何定义一个spin以及它的状态,如Ix, Iy, Iz。 当然,我们还需要描述coupled-spin systems. 简单的就是写那些symbols。矩阵将取决于你用什么space base.
(2)强脉冲通常用旋转矩阵来表达,evolution也用矩阵。
(3)一个脉冲序列的实验,就是一系列的矩阵相乘,再乘上系统的初始状态,就得到你在数据采集开始的系统状态,然后用FID就可以来描述。
关于这方面的资料比较多,列出一些供你参考:
(1)Operator formalisms: An overview
Author: Alex D. Bain
Journal: Concepts in Magnetic Resonance Part A
Year: 2006
Volume:28A
Number:6
Pages:369-383
(2) The product operator formalism: A physical and graphical interpretation
Author: David P. Goldenberg
Journal: Concepts in Magnetic Resonance Part A
Year: 2010
Volume: 36A
Number: 2
Pages: 49-83
(3)Product operator formalism for the description of NMR pulse experiments
Author: O. W. Sorensen and G. W. Eich and M. H. Levitt and G. Bodenhausen and R. R. Ernst
Journal:Progress in Nuclear Magnetic Resonance Spectroscopy
Year:1984
Volume:16
Pages:163-192