Abstract: Spatial distribution of radiofrequency field B₁ produced by self-made ³¹P NMR surfacecoil probe was studied.The results show ed that 90° pulse width at the center of the coil was 10μs, and that radiofrequency field B₁ contributing to the signals was limited within the circumference of the coil, and that along the axis perpendicular to the surface coil the intensity of B₁ decreased sharply with the increase of the distance from the coil.Simply speaking, the spatial distribution of effective B₁ of this surface coil can be considered as a sub-hemisphere, which has a bottom radius nearly equal to the coil radius and a maximum depth of action of about the coil radius.

Key words: Surface-coil probe, Radiofrequency field, Spatial distribution