EVIDENCE OF LARGE-ANGLE REORIENTATION IN SUPERCOOLED O-TERPHENYL

We study the reorientation process of a paramagnetic radical dissolved in supercooled o-terphenyl around and below T-g via the Electron Spin Resonance spectroscopy. The experimental results are at variance with the hypothesis of diffusive reorientation of the radical. Instead, the ESR lineshapes are fairly well reproduced by assuming that the radical reorientates via large angular jumps with a width Delta phi = 80 degrees(-5 degrees)(+10 degrees). The results are compared with previous H-2 NMR studies