连续波核磁共振实验中外扫描测量法的改进

Improvement of external scanning measurement method in continuous field scanning nuclear magnetic resonance experiment

本文对连续波核磁共振实验中外扫描法测横向弛豫时间误差的主要来源进行了分析,对系统误差的大小进行了定量估算.在此基础上,对外扫描法中横向弛豫时间的测量提出了相应的改进措施,通过计算确定了共振信号半高宽测量时共振信号应在的位置.结果表明,外扫描法测量中,通过x方向的相位调节把共振信号移到偏离中心适当距离的位置上来测量其半高宽,可有效降低非线性扫描电压引起的系统误差.此外,通过对误差大小及共振信号测量位置的计算,能加深学生对横向弛豫时间及外扫描测量法原理的理解.

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.