Fractional Rotational Diffusion and Anomalous Dielectric Relaxation in Dipole Systems

2006 ◽  
pp. 285-437 ◽  
Author(s):  
William T. Coffey ◽  
Yuri P. Kalmykov ◽  
Sergey V. Titov
Keyword(s):  
Dielectric Relaxation ◽  
Rotational Diffusion

The Application of the Memory-Function Formalism to Dielectric Relaxation

1980 ◽  
Vol 35 (11) ◽  
pp. 1207-1217
Author(s):  
P. Bordewijk
Keyword(s):  
Correlation Function ◽  
Dielectric Relaxation ◽  
Single Molecule ◽  
Rotational Diffusion ◽  
Memory Function ◽  
Dielectric Relaxation Time ◽  
Function Formalism ◽  
Correlation Theorem ◽  
Dipole Correlation ◽  
Rotational Diffusion Coefficient

Abstract The application of the memory-function formalism to dielectric relaxation is reconsidered. It is shown that the so-called Corresponding Micro-Macro Correlation theorem is not valid and that for a single macroscopic dielectric relaxation time, the single-molecule dipole correlation function may nevertheless be non-exponential. The deviations from the exponential decay for the single-molecule dipole correlation function are due to spatially dependent orientational correlations, and can at least partly be interpreted in terms of dielectric friction. The unsureness about these correlations implies that it is simpler to determine the rotational diffusion coefficient from the collective orientation correlation time as determined from dielectric measurements than from the single-molecule dipole correlation function as obtained from infrared spectroscopy.

scholarly journals Static and Dynamic Dielectric Properties of Mesogenic n-Nonyloxycyanobiphenyl (9OCB)

2007 ◽  
Vol 62 (1-2) ◽  
pp. 61-66
Author(s):  
Grzegorz Czechowski ◽  
Jan Jadżyn
Keyword(s):  
Activation Energy ◽  
Phase Transitions ◽  
Dielectric Properties ◽  
Dielectric Relaxation ◽  
Rotational Diffusion ◽  
Short Axis ◽  
Frequency Range ◽  
Static Permittivity ◽  
Anomalous Temperature ◽  
Smectic A

The dielectric properties of n-nonyloxycyanobiphenyl in the isotropic (I), nematic (N) and smectic A (SA) phases were investigated. The dielectric relaxation spectra, recorded in the frequency range 50 kHz - 100 MHz, were analyzed with use of the Cole-Cole equation. An anomalous temperature behavior of the static permittivity, the rotational diffusion exponent and the activation energy of mesogenic molecules rotating around their short axis, observed in the vicinity of the phase transitions, are discussed.

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