Cluster Model and IR Spectra of Fluids

In the context of cluster model of condensed state, the function of clusters distribution according to the number of particles contained in a cluster is proposed. With the use of the law of clusters distribution according to the number of particles in a cluster, the expressions for estimating the most probable, mean, and rms values of the number of particles in a cluster are obtained for simple and organic fluids depending on state parameters of the matter. In the context of the efficient-field theory, a relation is derived for prediction of frequencies in the IR spectrum of fluids which are connected with the presence of rotation and libration movements in the cluster structure. The verification of the proposed model is carried out for inert gases, nitrogen, oxygen, benzol, and water. The comparison of calculation results with experimental data demonstrates the adequacy of the proposed model for prediction of the number of particles in a cluster and frequencies of IR spectra in fluids.