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TY  - THES
AU  - Witt, Richard
TI  - Molekulare rotatorische Dynamik von Benzol und Pyridin in reiner Flüssigkeit und Benzol in einer Polymerlösung
CY  - Aachen
PB  - Publikationsserver der RWTH Aachen University
M1  - RWTH-CONV-114123
SP  - V, 74 S. : graph. Darst.
PY  - 2000
N1  - Aachen, Techn. Hochsch., Diss., 2000
AB  - The model of rotational diffusion was used to describe the rotational motion of benzene and pyridine in their neat liquids as well as benzene in a solution containing polystyrene. The three rotational diffusion constants cannot be determined solely by conventional spin-lattice relaxation measurements. In addition to conventional dipolar 13C-spin-lattice relaxation rates the cross correlation rates between the dipolar and 'chemical-shift anisotropy' mechanism were measured. Both relaxation pathways contain all necessary information about the molecular dynamics. From these rates the rotational diffusion constants were calculated. The investigated temperature range for benzene lay between 280 K and 323 K and for pyridine between 278 K and 318 K. The benzene/polystyrene solution was investigated at 298 K. Thus the activation parameters of reorientation for the molecules in their neat liquids could be determined. For both substances the motion about the 'out of plane' axis is fastest. The reorientation about the two perpendicular 'in plane' axes for pyridine are different; the motion about the axis through the nitrogene atom being slowest. The high dipolar moment of pyridine is probably the cause for the overall slower motion compared to that of the unpolar benzene. The reorientation about the 'out of plane' axis shows almost inertial behaviour whereas the motion about all other axes is very well described by the model of rotational diffusion.
LB  - PUB:(DE-HGF)11
UR  - https://publications.rwth-aachen.de/record/51874
ER  -