Multiple quantum correlated spectroscopy revamped by asymmetric z-gradient echo detection signal intensity as a function of the read pulse flip angle as verified by heteronuclear ~1H/~(31)P experiments

摘要

Heteronuclear multiple quantum (n=±0 and n=±2) correlated spectroscopy revamped by asymmetric z-gradient echo detection (CRAZED) experiments were performed on the spins 31P and ~1H in a H3PO4 solution in order to determine the optimum flip angle for the read pulse.It has been shown that for the negative quantum signals,the maximum signals appear at beta=0,and for the positive quantum signals,the maximum signals appear at beta=pi.The CRAZED signals were compared to the single quantum signals in two-pulse two-gradient experiments.It is found that the CRAZED signals can also be distinguished into gradient echoes and spin echoes.The gradient-echo-type CRAZED signal requires beta=0 and the spin-echo-type CRAZED signal requires beta=pi for maximum echo intensities,in the same way as in single quantum experiments.