title: Active sites in heterogeneous ice nucleation-the example of K-rich feldspars.
abstract: Ice formation on aerosol particles is a process of crucial importance to Earth's climate and the environmental sciences, but it is not understood at the molecular level. This is partly because the nature of active sites, local surface features where ice growth commences, is still unclear. Here we report direct electron-microscopic observations of deposition growth of aligned ice crystals on feldspar, an atmospherically important component of mineral dust. Our molecular-scale computer simulations indicate that this alignment arises from the preferential nucleation of prismatic crystal planes of ice on high-energy (100) surface planes of feldspar. The microscopic patches of (100) surface, exposed at surface defects such as steps, cracks, and cavities, are thought to be responsible for the high ice nucleation efficacy of potassium (K)-feldspar particles.
authors.affiliation: Atmospheric Aerosol Research Department, Institute for Meteorology and Climate Research (IMK-AAF), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz Platz 1, 76344 Eggenstein-Leopoldshafen, Germany. alexei.kiselev@kit.edu.
authors.forename: Alexei
authors.initials: A
authors.lastname: Kiselev
authors.affiliation: Atmospheric Aerosol Research Department, Institute for Meteorology and Climate Research (IMK-AAF), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz Platz 1, 76344 Eggenstein-Leopoldshafen, Germany.|Laboratory for Electron Microscopy (LEM), KIT, Engesserstrasse 7, 76131 Karlsruhe, Germany.
authors.forename: Felix
authors.initials: F
authors.lastname: Bachmann
authors.affiliation: London Centre for Nanotechnology, Thomas Young Centre, and Department of Chemistry, University College London (UCL), 17-19 Gordon Street, London WC1H 0AH, UK.
authors.forename: Philipp
authors.initials: P
authors.lastname: Pedevilla
authors.affiliation: London Centre for Nanotechnology, Thomas Young Centre, and Department of Chemistry, University College London (UCL), 17-19 Gordon Street, London WC1H 0AH, UK.
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Cox
authors.affiliation: London Centre for Nanotechnology, Thomas Young Centre, and Department of Physics and Astronomy, UCL, 17-19 Gordon Street, London WC1H 0AH, UK.
authors.forename: Angelos
authors.initials: A
authors.lastname: Michaelides
authors.affiliation: Laboratory for Electron Microscopy (LEM), KIT, Engesserstrasse 7, 76131 Karlsruhe, Germany.
authors.forename: Dagmar
authors.initials: D
authors.lastname: Gerthsen
authors.affiliation: Atmospheric Aerosol Research Department, Institute for Meteorology and Climate Research (IMK-AAF), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz Platz 1, 76344 Eggenstein-Leopoldshafen, Germany.|Institut für Umweltphysik, Universität Heidelberg, Im Neuenheimer Feld 229, Heidelberg, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Leisner