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Abstract
The orientational order parameters 
2 and
4, and the correlation times
0 and
2 of the androstane nitroxide spin probe dissolved in N-(4-butoxybenzylidene)-4'-butylaniline (4o.4), determined from the angular dependence of the nitrogen coupling constant and the linewidth in ESR spectra, have been reported as a function of temperature. For high ordered smectic G phase,
2 and
4 are in a very good approximation, assuming the molecular field theory. The activation energies in smectic G phase are found to be 16.4 kJ/mol for
0 and 29.6 kJ/mol for
2, respectively.