Компенсація ізотопних ефектів при ближній сольватації однозарядних іонів у легкій та важкій воді

• Дата: 2022
• Автори: Bulavin, V.I., Vyunnik, I.N.
• Формат: Стаття
• Мова: English; Ukrainian
• Опубліковано: Publishing house "Academperiodika" 2022
• Теми: solvent isotope effect; singly charged ions; diffusion; electrical conductivity; short-range solvation; negative solvation; ion near solvation; iзотопний ефект розчинника; однозаряднi iони; дифузiя; електрична провiднiсть; ближня сольватацiя; негативна сольватацiя; ближня сольватація іонів
• Онлайн доступ: https://ujp.bitp.kiev.ua/index.php/ujp/article/view/2020280
• Назва журналу: Ukrainian Journal of Physics

The diffusion coefficients Di0 and the microscopic characteristics of the diffusional displacement length d, time т, and velocity V of 18 singly charged ions (Li+, Na+, K+, Cs+, Me4N+, Et4N+, Pr4N+, Bu4N+, F-, Cl-, Br-, I-, ClO-3 , ClO-4 , BrO-3, IO-3 , IO-4 , and OBz-) in heavy and light waters at temperatures of 283.15 and 298.15 K have been calculated on the basis of literature data concerning the limiting molar electric conductivity of those ions. Using the proposed parameter (d-ri), where ri is the structural radius of an ion, the type of the solvation of those ions is determined: it is positive, if (d - ri) > 0, and negative, if (d - ri) < 0. The solvent isotope effects (SIEs) – namely, the variations of the ion diffusion coefficient, D0iH/D0iD, the length, dH/dD, time, тH/тD, and velocity, VH/VD, of the translational ion displacement, and the solvent viscosity, nD0/nH0, as a result of the substitution H → D in H2O – are calculated and analyzed. It is found that, in the case of SIE, the deviation of D0iH/D0iD or VH/VD from 1 can be up to 25.0–25.9%, whereas, for the near solvation SIE, the deviation of dH/dD from 1 is an order of magnitude lower. These facts are explained on the basis of a derived equation, where the SIE dH/dD is the product of the inverse SIEs nD0/nH0 and D0iH/D0iD. The low dH/dD-values are obtained due to the opposite effect of the indicated factors, which points to the compensation of the intermolecular and ion-molecular interactions. Hence, since those interactions govern the near solvation of singly charged ions in H2O and D2O, the results obtained testify to a significant solvent effect on this process.