【摘要】 频率合成激发核磁共振法是正在探索着的新方法,它较脉冲激发核磁共振法有很多优点。本文对该方法进行了计算机模拟,并对进一步开发它的应用进行了探讨更多还原

【Abstract】 The synthesis frequency excited NMR is a novel method in high resolution Fourier trasform NMR.It is different from pulse Fourier transform NMR.In pulse Fourier transform NMR, a pulsed radio-frequency signal is used to excitc the nuclear spin system. It has a uniform spectrum over the resonance frequencies,so that every nucleus suffers the same excitation. In synthesis frequency excitation, the intensity of the spectrum is not uniform. Its distribution may be dcsigned according to one’s desire. The nucleus’ resonance frequency within the enhanced frequency spectrum will be excited strongly.The nucleus’resonance frequency within weakened part will be excited weakly. The nucleus will not be excited if its resonance frequency falls into the spectrum at which its intensity is zero. The exciting signal is designed in frequency domain at first, then transformed into time domain and used in modulating the radio-frequency. It is not like the pulse Fourier transform NMR, which needs a high power pulsed exciting signal. The synthesis frequency excitation may be performed with a modif(?)ed continuous wave spectrometer. It has the same sensitivity as pulse Fourier transform NMR, but has not the shortcomings of the latter.In this paper, we described the principles of this novel method. For exploring its applications, we have made a computer simulation of the experiment, and got the same results as B. L. Tomlinson’s. We have designed several useful exciting signals. All the experiments have been simulated with a DJS-130 computer. Through the simulation, we have made clear that this method can be used in suppressing strong solvent peak, reducing dynamic range of NMR signal, exciting part spectrum for preventing the occurrence of fold, realizing homonuclear spin decoupling and multiple nuclear resonance. But this method is not suitable for relaxation time measurements.It is believed that this method will be useful in high resolution Fourier transform NMR.更多还原