Acoustic Relaxation in some Benzene Similar Compounds

摘要

The acoustic investigations in the group of cyclic compounds and particularly research of the dependencies of acoustic parameters and the structure of the organic liquids demonstrated some interesting regularities in the group of these compounds. In this paper the results of research in five cyclic liquids: bromo-, chloro-, fluoro- and jodobenzene were discussed in comparison to the benzene. The acoustic relaxation observed in all the compounds was found to result from Kneser's processes (vibrational relaxation). Based on investigations reported in this paper, as well as other, both experimental and literature data concerning a great number of compounds, one can draw a conclusion that almost all acoustic relaxation (Kneser-type) processes in liquids can be described using one relaxation time. It also seems that all vibrational degrees of freedom of the molecule take part in this process. It is known that arising of differences in transition probabilities could be caused by additional attraction in interaction of molecules having the dipole moments. A high value of dipole moments of halogenobenzenes with adequate benzene could be responsible for the difference of transition probabilities and changes of the relaxation times.