ELECTRON-SPIN DEPHASING MODEL FOR MOLECULAR-REORIENTATION - EXACT-SOLUTIONS

Electron spin coherence decay was recently applied to the molecular re orientation of spin probes. We employed the approximation of Van 't Ho f and Schmidt [C.A. Van't Hof and J. Schmidt, Chem. Phys. Letters 36 ( 1975) 460]. The approximation was not strictly applicable at low reori entation rates. We found the exact solutions to the coupled differenti al equations governing the magnetization. The real and imaginary parts of the characteristic matrix yield rate constants and resonance frequ ency shifts, respectively. The predicted temperature dependence of the coherence decay rates gives a narrower peak and is in better agreemen t with experiment.