How Ions Break Local Symmetry: Simulations of Polarized Transient Hole Burning for Different Models of the Hydrated Electron in Contact Pairs with Na+

• Published in: The journal of physical chemistry letters 2023-03, Vol.14 (12), p.3014-3022
• Main Authors: Park, Sanghyun J., Schwartz, Benjamin J.
• Format: Article
• Language: English
• Subjects: Chemistry; Materials Science; Physical Insights into Materials and Molecular Properties; Physics; Science & Technology - Other Topics
• ISSN: 1948-7185; 1948-7185
• DOI: 10.1021/acs.jpclett.3c00220

The hydrated electron (eaq –) is known via polarized transient hole-burning (pTHB) experiments to have a homogeneously broadened absorption spectrum. Here, we explore via quantum simulation how the pTHB spectroscopy of different eaq – models changes in the presence of electrolytes. The idea is that cation–eaq – pairing can break the local symmetry and, thus, induce persistent inhomogeneity. We find that a “hard” cavity model shows a modest increase in the pTHB recovery time in the presence of salt, while a “soft” cavity model remains homogeneously broadened independent of the salt concentration. We also explore the orientational anisotropy of a fully ab initio density functional theory-based model of the eaq –, which is strongly inhomogeneously broadened without salt and which becomes significantly more inhomogeneously broadened in the presence of salt. The results provide a direct prediction for experiments that can distinguish between different models and, thus, help pin down the hydration structure and dynamics of the eaq –.