Two kinds of methods to add reverse magnetic field have been recommended, one is adding compensating Helmholtz coils, another is applying direct current to the rapid scan sweep coils of ESR spectrometer.

• 本文介绍两种附加反向直流磁场的实验方法；即外加补偿的亥姆霍兹线圈；或直接借用ESR谱仪本身的快扫描线圈；来实现过零扫描.