This leads directly to the third consequence that the magnetization can not be efficiently tipped into the xy-plane because B eff does not lie in the xy-plane, as B 1 does. The motion of the magnetization now defines a cone. That means as Δω becomes larger, the magnetization is tipped less effectively into the xy-plane, and the FID signal decreases. In broad EPR spectra where Δω > ω 1 it is not possible to tip all the magnetization into the xy-plane to generate a strong FID signal. This is why it is important to maximize ω 1 or minimize the π/2 pulse length for broad EPR signals.