Vibrating sample magnetometer for protein research

A simple magnetometer for use with weakly paramagnetic frozen solutions is described. It uses the same superconducting coil for generating the field and detecting the vibrating magnetization. A nearly translationally invariant sample holder and low frequency vibration of large amplitude are advantageous. In a sample volume of 0.7 ml, 2×10-7 moles of a species having a single g=2, s=1/2 spin produces a signal reproducibly different from that of pure water, when the temperature is varied from 77 to 2 K. © 1972 The American Institute of Physics.