Temperature dependent statistical theory of two spin cross relaxations

Abstract A temperature dependent statistical theory of cross relaxation between two different spin systems is presented. An exact evaluation is made for the magnetic resonance line shape due to the diagonal part of the dipolar interaction at arbitrary temperatures. The cross relaxation transition probability is found to be inversely proportional to the Zeeman energy imbalance when it is large compared to dipolar energy. This seems to agree with the Mims experiment on Ruby in the negative frequency range.