Segreto Nico, Schwarz Tim M, Dietrich Carolin A, Stender Patrick, Schuldt Robin, Schmitz Guido, Kästner Johannes
Institute for Theoretical Chemistry, University of Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart, Germany.
Institute for Materials Science, Chair of Materials Physics, University of Stuttgart, Heisenbergstraße 3, 70569 Stuttgart, Germany.
J Phys Chem A. 2022 Aug 25;126(33):5663-5671. doi: 10.1021/acs.jpca.2c04163. Epub 2022 Aug 16.
We investigated the field evaporation process of frozen water in atom probe tomography (APT) by density functional simulations. In previous experiments, a strong tailing effect was observed for peaks caused by the molecular structure (HO)H, in contrast to other peaks. In purely field-induced and thermally assisted evaporation simulations, we found that chains of protonated water molecules were pulled out of the dielectric surface by up to 6 Å, which are stable over a wide range of field strengths. Therefore, the resulting water clusters experience only part of the acceleration after evaporation compared to molecules evaporating directly from the surface and, thus, exhibit an energy deficit, which explains the tailing effect. Our simulations provide new insight into the complex evaporation behavior of water in high electrical fields and reveal possibilities for adapting the existing reconstruction algorithms.
我们通过密度泛函模拟研究了原子探针断层扫描（APT）中冷冻水的场蒸发过程。在先前的实验中，与其他峰相比，由分子结构（HO）H引起的峰观察到强烈的拖尾效应。在纯场诱导和热辅助蒸发模拟中，我们发现质子化水分子链被从介电表面拉出多达6 Å，在很宽的场强范围内都是稳定的。因此，与直接从表面蒸发的分子相比，蒸发后形成的水团簇仅经历部分加速，从而表现出能量不足，这就解释了拖尾效应。我们的模拟为高电场中水分子复杂的蒸发行为提供了新的见解，并揭示了改进现有重建算法的可能性。
