Issues

When the spin of an unpaired electron changes orientation in a magnetic field, the energy absorbed is a clue to the nature of the molecule (or fragment). By measuring field strength and the frequency of radiation causing the flip, chemists can use this relatively new phenomenon to identify radicals, measure coupling between electronic and nuclear spins and determine the influence of surrounding material. The author is Eugene Higgins professor of physical chemistry at Princeton University.

The fourth biennial physics apparatus exhibit was held last January during the joint annual meeting of the American Association of Physics Teachers and the American Physical Society in New York. Dr. Christensen has served since 1963 as head of the AAPT‐AIP Center for Educational Apparatus in Physics while on leave from St. Olaf College in Minnesota, where he is associate professor of physics.