Short-time rotational relaxation in supercooled and glassy o-terphenyl:: a nonlinear electron spin resonance study by using molecular probes with different symmetries

被引:5
作者
Andreozzi, L
Faetti, M
Hvala, M
Giordano, M
机构
[1] Univ Pisa, Dipartimento Fis, I-56126 Pisa, Italy
[2] UdR Pisa, Ist Nazl Fis Mat, Pisa, Italy
来源
PHILOSOPHICAL MAGAZINE B-PHYSICS OF CONDENSED MATTER STATISTICAL MECHANICS ELECTRONIC OPTICAL AND MAGNETIC PROPERTIES | 1999年 / 79卷 / 11-12期
关键词
D O I
10.1080/13642819908223087
中图分类号
T [工业技术];
学科分类号
08 ;
摘要
The short-time rotational dynamics of nearly spherical and cylindrical spin probes in supercooled and glassy o-terphenyl is investigated by nonlinear electron spin resonance spectroscopy. At higher temperatures, the relaxation is exponential and the Debye-Stokes-Einstein law holds, tau proportional to (eta/T). tau is the rotational correlation time, eta the shear viscosity and T the temperature. On cooling, the coupling of the short-time rotational dynamics and the shear viscosity weakens, and a fractional Debye-Stokes-Einstein law tau proportional to (eta/T)(xi), with xi constant, is observed. At the lower temperatures, the rotation is activated. A scaling of the short-time rotational dynamics of the different molecular probes is obtained for the overall range of temperature.
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页码:1993 / 2003
页数:11
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