The line shapes of the E.S.R. spectrum of a system of interacting triplets

The system considered is one in which the spectral lines are broadened by collisions between triplets. During a collision a pair of triplets interacts with the coupling J S 1.S 2. It is found that the lines of the zero field spectrum are shifted and broadened; the direction of the shift depends on the magnitude of the coupling J, and on the life-time of the collision. Similar results are predicted for the high field spectrum, although in this case eventually the two lines collapse into a single exchange narrowed line.