Proposed Use of Magnetic Fields in Electron Microscopic Radioautography

THE use of strong magnetic fields has been proposed as a possible way of increasing resolution in radio-autography 1 . It was reasoned that a sufficiently strong magnetic field would bend the path of emitted β-particles into a circle of arbitrarily small radius, thereby restricting the resulting radioautographic grains to a small zone around the source. In recent reports 2,3 , Harford and Hamlin, using the same argument, attempted to improve the resolution of electron microscopic radioautographs by placing the specimens in a 10-kilogauss magnetic field during exposure. They could not demonstrate such an improvement; but they attributed a considerable increase in the number of exposed grains to the effect of the field on the β-particles from tritium.