Abstract: The main reason for the measurement error of transverse relaxation time by external scanning method in continuous field scanning nuclear magnetic resonance experiment is analyzed. The magnitude of the systematic error is quantitatively estimated. On this basis, the corresponding improvement measures are proposed for the measurement of transverse relaxation time in the external scanning method. The position of the resonance signal in the measurement of the full width at half maximum (FWHM) of the resonance signal is calculated. The results show that the system error caused by nonlinear scanning voltage can be effectively reduced by moving the resonant signal to an appropriate position though adjusting the phase of scanning voltage in the measurement of FWHM of the resonance signal. In addition, the calculation of the magnitude of error and the measurement position of resonance signals can make students' deeply understand the transverse relaxation time and external scanning measurement method.

Key words:  nuclear magnetic resonance, external scanning method, transverse relaxation time, systematic error