Studies on interactions and transport coefficients of ions in gases

Abstract

The thesis consists of three parts. In the first part, we develop combination rules for dispersion coefficients by way of a parameter corresponding to an effective number of equivalent electrons, the same parameter N that appears in the Slater-Kirkwood formula for the dipole-dipole coefficient. Furthermore, the use of the same value of N for isoelectronic systems in determining dispersion coefficients is empirically established. The only additional input data needed are static multipole polarizabilities. Extensive empirical testing suggests that the results are accurate within 5% for dipole coefficients and about 5-10% for higher coefficients. These results apply only to S-state atoms and ions but should be capable of extension to other systems.In the second part of the thesis we develop two-parameter models for the known halogen ion-, noble gas- and alkali ion-noble gas potentials. The models consist of two parts. One of them includes the dispersion and induction energies, and the other part includes exchange energies which are found to scale for each of the above categories of systems.The developed models fit the experimental potentials quite accurately and in the case of ion-atom systems reproduce the ion-transport data satisfactorily. A subsequent correlation of the model- parameters enabled us to predict new potentials. It is expected that similar models apply to other non-bonded interactions.In the last part of the thesis we develop Generalized Einstein Relations, that is, relations between diffusion and mobility coefficients, for ions in molecular gases. These relations have a firm basis in the Wang Chang-Uhlenbeck-de Boer kinetic equation and they include as a special the GER's for elastic interactions developed in the past. In addition, we derive a new procedure to determine diffusion coefficients from mobilities that apply to elastic as well as to inelastic systems. This procedure is quite simple and also accurate as its testing, against results of rigorous kinetic theories and experimental data, has revealed. These results do not apply to systems involving charge transfer or reactive interactions but should be capable of extension to them.

Η διατριβή περιλαμβάνει την παραγωγή σχέσεων για τον υπολογισμό συντελεστών διασποράς που εμφανίζονται στην ανάπτυξη των διαμοριακών δυναμικών σε ασυμπτωτικές σειρές, την κατασκευή προτύπου διαμοριακού δυναμικού για την περιγραφή συστημάτων ιόντων- ευγενών αερίων, καθώς και την ανάπτυξη σχέσεων για την παραγωγή συντελεστών διάχυσης ιόντων σε αέρια από την ευκινησία και τις διαμοριακές αλληλεπιδράσεις. Οι σχέσεις αυτές ονομάζονται "Γενικευμένες σχέσεις Αϊνστάιν", (Generalized Einstein Relations), και βασίζονται στην αναλυτική επίλυση της Wang Chang- Uhlenbeck- de Boer κινητικής εξίσωσης γιά την κίνηση μοριακών ιόντων σε αέρια υπό την επίδραση ηλεκτροστατικού πεδίου.