Browsing by Author "Reischl, Bernhard"
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- Ab initio Kinetic Monte Carlo simulations of dissolution at the NaCl-water interface
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä(2014) Chen, Jian-Cheng; Reischl, Bernhard; Spijker, Peter; Holmberg, Nico; Laasonen, Kari; Foster, Adam S. - Atomic structure and water arrangement on K-feldspar microcline (001)
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä(2024-02-21) Dickbreder, Tobias; Sabath, Franziska; Reischl, Bernhard; Nilsson, Rasmus V.E.; Foster, Adam S.; Bechstein, Ralf; Kühnle, AngelikaThe properties of clouds, such as their reflectivity or their likelihood to precipitate, depend on whether the cloud droplets are liquid or frozen. Thus, understanding the ice nucleation mechanisms is essential for the development of reliable climate models. Most ice nucleation in the atmosphere is heterogeneous, i.e., caused by ice nucleating particles such as mineral dusts or organic aerosols. In this regard, K-feldspar minerals have attracted great interest recently as they have been identified as one of the most important ice nucleating particles under mixed-phase cloud conditions. The mechanism by which feldspar minerals facilitate ice nucleation remains, however, elusive. Here, we present atomic force microscopy (AFM) experiments on microcline (001) performed in an ultrahigh vacuum and at the solid-water interface together with density functional theory (DFT) and molecular dynamics (MD) calculations. Our ultrahigh vacuum data reveal features consistent with a hydroxyl-terminated surface. This finding suggests that water in the residual gas readily reacts with the surface. Indeed, the corresponding DFT calculations confirm a dissociative water adsorption. Three-dimensional AFM measurements performed at the mineral-water interface unravel a layered hydration structure with two features per surface unit cell. A comparison with MD calculations suggests that the structure observed in AFM corresponds to the second hydration layer rather than the first water layer. In agreement with previous computation results, no ice-like structure is seen, questioning an explanation of the ice nucleation ability by lattice match. Our results provide an atomic-scale benchmark for the clean and water-covered microcline (001) plane, which is mandatory for understanding the ice nucleation mechanism on feldspar minerals. - Atomistic Simulations of Solid-Liquid Interfaces
School of Science | Doctoral dissertation (article-based)(2013) Reischl, BernhardSolid-liquid interfaces can be encountered in systems and processes ranging from biomineralization to fuel cell technology, and play an important role in growth or dissolution mechanisms of particles or surfaces in solution. The surface-induced changes of material properties not only affect the solid, but also the liquid itself: the structure of the liquid at the interface is very different from bulk. Understanding these processes occurring at solid-liquid interfaces at the atomistic scale is fundamental to a wide range of disciplines. New insight can be gained by combining cutting edge experimental techniques and computer simulations. The atomic force microscope (AFM) can be used to study solid-liquid interfaces in high resolution. We have developed new simulation methods, based on atomistic molecular dynamics and free energy calculations in order to model the complex imaging mechanism. In addition to the direct interactions between AFM tip and surface, our approach takes into account entropic contributions from interactions with water molecules in hydration layers on top of the surface as well as in the solvation shell of the AFM tip. For the Calcite (10-14) surface in water, we find good agreement between our simulations and recent 3D AFM data. We have also developed and tested a simple model to calculate AFM images only from differences in equilibrium local water density in hydration layers, reducing the computational cost by up to three orders of magnitude compared to free energy calculations including an explicit AFM tip. We have further studied the hydration layer structure and dissociation kinetics of the NaCl (100) surface in water from ab initio molecular dynamics, as well as the role of surface premelting of ice in the context of atomic scale friction at the ice-ice interface. - Flexible and modular virtual scanning probe microscope
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä(2015) Tracey, John; Federici Canova, Filippo; Keisanen, Olli; Gao, David Z.; Spijker, Peter; Reischl, Bernhard; Foster, Adam S. - Liquid Water and Interfacial, Cubic, and Hexagonal Ice Classification through Eclipsed and Staggered Conformation Template Matching
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä(2021-04-22) Roudsari, Golnaz; Veshki, Farshad G.; Reischl, Bernhard; Pakarinen, Olli H.We propose a novel method based on template matching for the recognition of liquid water, cubic ice (ice Ic), hexagonal ice (ice Ih), clathrate hydrates, and different interfacial structures in atomistic and coarse-grained simulations of water and ice. The two template matrices represent staggered and eclipsed conformations, which are the building blocks of hexagonal and cubic ice and clathrate crystals. The algorithm is rotationally invariant and highly robust against imperfections in the ice structure, and its sensitivity for recognizing ice-like structures can be tuned for different applications. Unlike most other algorithms, it can discriminate between cubic, hexagonal, clathrate, mixed, and other interfacial ice types and is therefore well suited to study complex systems and heterogeneous ice nucleation. - Mechanism of atomic force microscopy imaging of three-dimensional hydration structures at a solid-liquid interface
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä(2015) Fukuma, Takeshi; Reischl, Bernhard; Kobayashi, Naritaka; Spijker, Peter; Federici Canova, Filippo; Miyazawa, Keisuke; Foster, Adam S.Here we present both subnanometer imaging of three-dimensional (3D) hydration structures using atomic force microscopy (AFM) and molecular dynamics simulations of the calcite-water interface. In AFM, by scanning the 3D interfacial space in pure water and recording the force on the tip, a 3D force image can be produced, which can then be directly compared to the simulated 3D water density and forces on a model tip. Analyzing in depth the resemblance between experiment and simulation as a function of the tip-sample distance allowed us to clarify the contrast mechanism in the force images and the reason for their agreement with water density distributions. This work aims to form the theoretical basis for AFM imaging of hydration structures and enables its application to future studies on important interfacial processes at the molecular scale. - Tip dependence of three-dimensional scanning force microscopy images of calcite-water interfaces investigated by simulation and experiments
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä(2020-06-28) Miyazawa, Keisuke; Tracey, John; Reischl, Bernhard; Spijker, Peter; Foster, Adam S.; Rohl, Andrew L.; Fukuma, TakeshiIn this study, we have investigated the influence of the tip on the three-dimensional scanning force microscopy (3D-SFM) images of calcite-water interfaces by experiments and simulations. We calculated 3D force images by simulations with the solvent tip approximation (STA), Ca, CO3 and OH tip models. For all the 3D images, the z profiles at the surface Ca and CO3 sites alternately show oscillatory peaks corresponding to the hydration layers. However, the peak heights and spacings become larger when the mechanical stability of the tip becomes higher. For analyzing the xy slices of the 3D force images, we developed the extended STA (E-STA) model which allowed us to reveal the strong correlation between the hydration structure just under the tip and the atomic-scale force contrasts. Based on these understandings on the image features showing the strong tip dependence, we developed a method for objectively estimating the similarity between 3D force images. With this method, we compared the simulated images with the three experimentally obtained ones. Among them, two images showed a relatively high similarity with the image obtained by the simulation with the Ca or the CO3 tip model. Based on these agreements, we characterized the hydration structure and mechanical stability of the experimentally used tips. The understanding and methodology presented here should help us to derive accurate information on the tip and the interfacial structure from experimentally obtained 3D-SFM images. - Understanding 2D atomic resolution imaging of the calcite surface in water by frequency modulation atomic force microscopy
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä(2016-09-09) Tracey, John; Miyazawa, Keisuke; Spijker, Peter; Miyata, Kazuki; Reischl, Bernhard; Canova, Filippo Federici; Rohl, Andrew L.; Fukuma, Takeshi; Foster, Adam S.Frequency modulation atomic force microscopy (FM-AFM) experiments were performed on the calcite (1014) surface in pure water, and a detailed analysis was made of the 2D images at a variety of frequency setpoints. We observed eight different contrast patterns that reproducibly appeared in different experiments and with different measurement parameters. We then performed systematic free energy calculations of the same system using atomistic molecular dynamics to obtain an effective force field for the tip-surface interaction. By using this force field in a virtual AFM simulation we found that each experimental contrast could be reproduced in our simulations by changing the setpoint, regardless of the experimental parameters. This approach offers a generic method for understanding the wide variety of contrast patterns seen on the calcite surface in water, and is generally applicable to AFM imaging in liquids.