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Abstract
The infrared and Raman spectra for durene, tetracyanobenzene and their 1 : 1 complex were studied. Simultaneously the neutron scattering experiments (INS and QENS) were performed. A detailed analysis of the modes assigned to the methyl groups vibrations were analyzed based on the simulated frequencies and intensities by using the GAUSSIAN-03 and auntie-CLIMAX programs. A good agreement between calculated frequencies and INS experimental ones was found. Moreover the calculations generate, with a quite high accuracy, the observed lattice phonons below 70 cm−1. The QENS studies have shown that the activation energy for the 120° CH3 jumps equal to 49 ± 13 meV for durene and 35 ± 12 meV for the complex confirming that the complexation leads to a decrease of the potential barrier for the methyl group rotations.
¥ Dedicated to Professor Jerzy A. Janik on the occasion of his 80th birthday.
Acknowledgements
The authors would like to thank Professor J. A. Janik for his interest in the work and for fruitful discussions. Two of the authors (JK and MNK) would also like to thank Dr. A. V. Puchkov and Dr. A. N. Skomorokhov from IPPE in Obninsk for their help and hospitality during the QENS measurements. Financial support from the Ministry of Science and Informatics (Grant 4T09A 05125) is acknowledged. Calculations have been performed in the Interdisciplinary Centre for Mathematical and Computational Modelling, Warsaw University (Grant G30-15).
Notes
¥ Dedicated to Professor Jerzy A. Janik on the occasion of his 80th birthday.