NH$_3$ adsorption and competition with H$_2$O on a hydroxylated aluminosilicate surface
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| Main Authors: | , , , , , , |
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| Format: | Preprint |
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2024
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| _version_ | 1866909183112118272 |
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| author | Franceschi, Giada Conti, Andrea Lezuo, Luca Abart, Rainer Mittendorfer, Florian Schmid, Michael Diebold, Ulrike |
| author_facet | Franceschi, Giada Conti, Andrea Lezuo, Luca Abart, Rainer Mittendorfer, Florian Schmid, Michael Diebold, Ulrike |
| contents | The interaction between ammonia (NH$_3$) and (alumino)silicates is of fundamental and applied importance, yet the specifics of NH$_3$ adsorption on silicate surfaces remain largely unexplored, mainly because of experimental challenges related to their electrically insulating nature. An example of this knowledge gap is evident in the context of ice nucleation on silicate dust, wherein the role of NH$_3$ for ice nucleation remains debated. This study explores the fundamentals of the interaction between NH$_3$ and microcline feldspar (KAlSi$_3$O$_8$), a common aluminosilicate with outstanding ice nucleation abilities. Atomically resolved non-contact atomic force microscopy, x-ray photoelectron spectroscopy, and density functional theory-based calculations elucidate the adsorption geometry of NH$_3$ on the lowest-energy surface of microcline, the (001) facet, and its interplay with surface hydroxyls and molecular water. NH$_3$ and H$_2$O are found to adsorb molecularly in the same adsorption sites, creating H-bonds with the proximate surface silanol (Si-OH) and aluminol (Al-OH) groups. Despite the closely matched adsorption energies of the two molecules, NH$_3$ readily yields to replacement by H$_2$O, challenging the notion that ice nucleation on microcline proceeds via the creation of an ordered H$_2$O layer atop pre-adsorbed NH$_3$ molecules. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2404_17436 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | NH$_3$ adsorption and competition with H$_2$O on a hydroxylated aluminosilicate surface Franceschi, Giada Conti, Andrea Lezuo, Luca Abart, Rainer Mittendorfer, Florian Schmid, Michael Diebold, Ulrike Mesoscale and Nanoscale Physics The interaction between ammonia (NH$_3$) and (alumino)silicates is of fundamental and applied importance, yet the specifics of NH$_3$ adsorption on silicate surfaces remain largely unexplored, mainly because of experimental challenges related to their electrically insulating nature. An example of this knowledge gap is evident in the context of ice nucleation on silicate dust, wherein the role of NH$_3$ for ice nucleation remains debated. This study explores the fundamentals of the interaction between NH$_3$ and microcline feldspar (KAlSi$_3$O$_8$), a common aluminosilicate with outstanding ice nucleation abilities. Atomically resolved non-contact atomic force microscopy, x-ray photoelectron spectroscopy, and density functional theory-based calculations elucidate the adsorption geometry of NH$_3$ on the lowest-energy surface of microcline, the (001) facet, and its interplay with surface hydroxyls and molecular water. NH$_3$ and H$_2$O are found to adsorb molecularly in the same adsorption sites, creating H-bonds with the proximate surface silanol (Si-OH) and aluminol (Al-OH) groups. Despite the closely matched adsorption energies of the two molecules, NH$_3$ readily yields to replacement by H$_2$O, challenging the notion that ice nucleation on microcline proceeds via the creation of an ordered H$_2$O layer atop pre-adsorbed NH$_3$ molecules. |
| title | NH$_3$ adsorption and competition with H$_2$O on a hydroxylated aluminosilicate surface |
| topic | Mesoscale and Nanoscale Physics |
| url | https://arxiv.org/abs/2404.17436 |