Abstract：
The determination of gas phase thermochemical properties of per- and polyfluoroalkyl substances (PFAS) is central to understanding the long-range transport behavior of PFAS in the atmosphere. Prior gas-phase studies have reported the properties of perfluorinated sulfonic acid (PFOS) and perfluorinated octanoic acid (PFOA). Here, this study reports the gas phase enthalpies of formation of short- and long-chain PFAS and their precursor molecules determined using density functional theory (DFT) and ab initio approaches. Two density functionals, two ab initio methods and an empirical method were used to compute enthalpies of formation with the total atomization approach and an isogyric reaction. The performance of the computational methods employed in this work were validated against the experimental enthalpies of linear alkanoic acids and perfluoroalkanes. The gas-phase determinations will be useful for future studies of PFAS in the atmosphere, and the methodological choices will be helpful in the study of other PFAS.
摘要：
测定全氟烷基和多氟烷基物质（PFAS）的气相热化学性质对于了解PFAS在大气中的远距离迁移行为至关重要。先前的气相研究已经报道了全氟磺酸(PFOS)和全氟辛酸(PFOA)的性质。这里,这项研究报告了使用密度泛函理论（DFT）和从头算方法确定的短链和长链PFAS及其前体分子形成的气相焓。两个密度泛函，使用两种从头算方法和一种经验方法来计算全雾化方法和等激素反应的形成焓。针对线性链烷酸和全氟烷烃的实验焓，验证了这项工作中采用的计算方法的性能。气相测定将有助于未来大气中PFAS的研究，方法的选择将有助于其他PFAS的研究。
