engleski

Fast motion in molecular solids at low temperatures: evidence from a pulsed EPR study of nitroxyl radical relaxation

We have investigated the electron phase-memory relaxation time of the nitroxyl radical TEMPO at temperatures between 5 and 80 K in crystalline and glassy states of ethanol using pulsed X-band electron paramagnetic resonance spectroscopy. The results indicate that the transition from the slow to fast motion regimes of the paramagnetic center occurs upon further cooling of the sample below ca. 20 K. We provide experimental evidence that this phenomenon cannot be ascribed to the impact of hyperfine interactions with methyl protons in the system but it can be instead a signature of the coupling of the electron spin with the boson peak excitations of the lattice.

boson peak ; glass ; relaxation

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