Nuclear structure and properties are mainly studied by utilizing large-scale equipment such as colliders, while the chemical behavior of isotopes and their isotopologues emerges as a critical approach to investigating nuclei. Studies of isotope effects (IEs) primarily focus on the isotope separation or kinetic isotope effects of light isotopes such as H/D/T caused by mass-dependent IEs. However, barely any study has investigated whether the neutral neutron could remarkably influence medium-heavy isotopes as catalysts, since they are usually regarded as chemically similar, exhibiting inapparent mass differences. Herein, we revealed a remarkable IE of 107Ag and 109Ag with the photogenerated ability of their Ag2O isotopologues, 107Ag2O and 109Ag2O, exceeding 19.9%, despite a mass difference of less than 2%. Based on this IE in photochemistry, we processed methyl orange degradation as the model reaction and obtained an unprecedented IE k107/k109 = 1.1 with 107Ag2O and 109Ag2O serving as photocatalysts, respectively. The correlation of extranuclear electrons and the nucleus has been quantified for the first time by both theoretical calculations and experimental results, which is proportional to the Ag isotopes' nuclear charge density. This work extends our fundamental understanding of how the "humble" neutron affects extranuclear electrons during the photochemical process.
Xue et al. (Wed,) studied this question.