SIMILARITY OF PHYSICOCHEMICAL PROPERTIES OF ALKALINE EARTH ELEMENTS WITH RARE EARTH ELEMENTS. I. INTERNAL STARK EFFECT AND ITS APPLICATION TO THE ENERGY OF IONIZATION OF COMPOUNDS OF THESE ELEMENTS. IA – MONOHALIDES AND MONOHYDROXIDE OF STRONTIUM

The internal Stark effect is presented in development, applied to the study of ionization potentials (eV, ±0.017): 5.422 – SrOH, 5.257 – SrF, 5.523 – SrCl, 5.581 – SrBr, 5.661 – SrJ, 5.525 – CaF, 5.873 – CaCl, dissociation energies (kJ/mol) 582±6 (Sr+-F), 430.8±2.1 (Sr+-OH) and polarizabilities of the Sr+ cation in these ionic compounds 1.117±0.014 (X2Σ+) and 1.986±0.017 Å3 (B2Σ+). The result of the development is the creating of a method for determining the adiabatic ionization potential Io of polar molecules M+X– with high accuracy (not worse than ±0.02 eV) and in short time based on spectroscopic data. The developed method is based on the shift of the electron terms of the molecule by the internal field of the anion X–, which form the beginning (and not the difficult to measure ionization limit) of the Rydberg series in the spectrum. This is the fundamental novelty of the approach to solving this complex problem. The calculation of each takes several minutes on a calculator. The new method is compared with most frequent used in researches existed and outlined in literature. From comparison the conclusion is made about high accuracy of developed method excelling those that are presented in literature and used in research. In connection with this is proposed to make this method for determining the adiabatic ionization potentials of ionic molecules a part of spectroscopic studies along with the determination of other molecular parameters from the spectra: internuclear distances, nuclear vibration frequencies, energies of electron states, etc. The more precise data are presented about dissociation energies of ions (kJ/mol) Do(Sr+-F)=582±6 и Do(Sr+-OH)=430.8±2.1. The new and more accurate data are obtained about polarizabilities of Sr+ ion in molecules of monohalides including its excited states (Å3): 1.117±0.014 in ground state, – σ(5s)X2Σ+, and 1.986±0.017 in first excited one – σ(5p)B2Σ+, same symmetry that ground one. For citation: Belyaev V.N., Rybkin V.V. Similarity of physicochemical properties of alkaline earth elements with rare earth elements. I. Internal Stark effect and its application to the energy of ionization of compounds of these elements. Ia – monohalides and monohydroxide of strontium. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2025. V. 68. N 6. P. 15-28. DOI: 10.6060/ivkkt.20256806.7177.