成都理工大学刘耘团队报道了以氯类对汞氧化的个例研究，揭示了动力学同位素分馏中的核体积效应。该项研究成果发表在2024年4月7日出版的《地球化学学报》上。

在该工作中，研究人员选择了几种具代表性的掺汞物质的总分馏分数(MDFs+NVE诱导的MIFs)，对平衡过程和动力学过程进行了从头计算。研究使用Gathemsian09和DIRAC19软件包(称为电子密度标度法)，通过对其准确性和误差性的系统评估，使用原子核的标度接触电子密度计算NVE诱导的MIFs。此外，研究还使用该方法计算了几种具有代表性的氯类对汞的氧化反应中，汞同位素的NVE诱导动力学同位素效应(KIE)。²⁰²Hg/¹⁹⁸Hg的总标准从-2.27‰到0.96‰。

观测到三个由NVE引起的异常的²⁰²Hg的富集KIEs(δ²⁰²Hg/¹⁹⁸Hg=0.83‰，0.94‰和0.96‰)，这与经典观点（轻同位素反应快于重同位素）截然不同。研究结果强调，本文建立的电子密度标度方法可以为计算重同位素的NVE诱导的KIEs提供一种更简单的方法，并有助于更好地理解汞同位素体系的分馏机制。

众所周知，汞(Hg)的平衡同位素分馏包括经典的质量相关分馏(MDFs)，和核体积效应(NVE)诱导的质量无关分馏(MIFs)。然而，NVE对这些动力学过程的影响尚不清楚。

附：英文原文

Title: Nuclear volume effects in kinetic isotope fractionation: A case study of mercury oxidation by chlorine species

Author: Yang, Chenlu, Zhang, Yining, Liu, Yun

Issue&Volume: 2024-04-07

Abstract: It is well-known that the equilibrium isotope fractionation of mercury (Hg) includes classical mass-dependent fractionations (MDFs) and nuclear volume effect (NVE) induced mass-independent fractionations (MIFs). However, the effect of the NVE on these kinetic processes is not known. The total fractionations (MDFs+NVE-induced MIFs) of several representative Hg-incorporated substances were selected and calculated with ab initio calculations in this work for both equilibrium and kinetic processes. NVE-induced MIFs were calculated with scaled contact electron densities at the nucleus through systematic evaluations of their accuracy and errors using the Gaussian09 and DIRAC19 packages (named the electron density scaling method). Additionally, the NVE-induced kinetic isotope effect (KIE) of Hg isotopes are also calculated with this method for several representative Hg oxidation reactions by chlorine species. Total KIEs for ²⁰²Hg/¹⁹⁸Hg ranging from-2.27‰ to 0.96‰ are obtained. Three anomalous ²⁰²Hg-enriched KIEs (δ²⁰²Hg/¹⁹⁸Hg=0.83‰, 0.94‰, and 0.96‰,) caused by the NVE are observed, which are quite different from the classical view (i.e., light isotopes react faster than the heavy ones). The electron density scaling method we developed in this study can provide an easier way to calculate the NVE-induced KIEs for heavy isotopes and serve to better understand the fractionation mechanisms of mercury isotope systems.

DOI: 10.1007/s11631-024-00691-5

Source: https://link.springer.com/article/10.1007/s11631-024-00691-5