Thermodynamical quantities of silver mono halides from spectroscopic data

The diatomic molecules have gained increased interest over the past several years in both experiment and theoretical studies because of their importance in astrophysical processes and many chemical reactions. Thermodynamical quantities such as enthalpy, entropy, heat capacity and free energy have their potential applications in various fields of science. Investigations in high temperature chemistry, astrophysics, and other disciplines require the knowledge of the thermodynamic properties of diatomic molecules. The plausibility of predictive models obtained in such investigations relies on the accuracy of these data. The scrutiny of the literature reveals that thermodynamic data are often absent or have scattered values in different research articles and handbooks. The main requirements to thermodynamic values are their reliability, mutual consistency, and so forth. In the present theoretical study, thermodynamic values are estimated by using spectroscopic data which are microscopic in nature, whereas thermodynamical quantities are macroscopic in nature. Attempts have been made to calculate the thermodynamical quantities of silver monohalides (AgF, AgCl, AgBr and AgI) from spectroscopic data with the help of partition function theory. The results have been calculated in the temperature range 100-3000 degrees C. In order to increase accuracy of the calculated quantities, we have incorporated non-rigidity, anharmonocity, and stretching effects of molecules. The variation of these quantities with temperature have been studied and explained in terms of various modes of molecular motions.