A study of the rotation dynamics of spin probe TEMPO by electron spin resonance (ESR) spectroscopy in a series of six short- and medium-sized n-alkanes is presented. In addition to the usual crossover effects connected with the solid-liquid phase transitions at the temperature Tm and the solid-solid transition one at Tss, we find a strong correlation between the change in reorientation at the characteristic ESR temperature TX1fast < Tss and/or Tm with the ratio TX1fast/Tm = 0.76 ± 0.03 and the characteristic dynamic temperature, TX, obtained from the viscosity data. This indicates the presence of local disordered regions inside the crystalline structure which is indeed sensitive to their dynamic change at the crossover temperature TX ≅ TX1fast.
ESR evidence of the dynamic crossover in the supercooled liquid states of a series of solid n - alkanes
Carmelo CorsaroSecondo
;Domenico Mallamace;
2018-01-01
Abstract
A study of the rotation dynamics of spin probe TEMPO by electron spin resonance (ESR) spectroscopy in a series of six short- and medium-sized n-alkanes is presented. In addition to the usual crossover effects connected with the solid-liquid phase transitions at the temperature Tm and the solid-solid transition one at Tss, we find a strong correlation between the change in reorientation at the characteristic ESR temperature TX1fast < Tss and/or Tm with the ratio TX1fast/Tm = 0.76 ± 0.03 and the characteristic dynamic temperature, TX, obtained from the viscosity data. This indicates the presence of local disordered regions inside the crystalline structure which is indeed sensitive to their dynamic change at the crossover temperature TX ≅ TX1fast.File | Dimensione | Formato | |
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