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Conference Paper: Metal-ion solvation and abundance in atmospheric media before strong earthquakes
Title | Metal-ion solvation and abundance in atmospheric media before strong earthquakes |
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Authors | |
Keywords | [0335] ATMOSPHERIC COMPOSITION AND STRUCTURE - Ion chemistry of the atmosphere [1011] GEOCHEMISTRY - Thermodynamics [2419] IONOSPHERE - Ion chemistry and composition [7223] SEISMOLOGY - Earthquake interaction, forecasting, and prediction |
Issue Date | 2009 |
Publisher | American Geophysical Union (AGU) |
Citation | The 2009 Fall Meeting of the American Geophysical Union (AGU), San Francisco, CA., 14-18 December 2009. How to Cite? |
Abstract | Gas phase metal-ions form hydrated complexes, which have characteristic solvation enthalpies ranging from around -150kJ/mol for monohydrates to around -40kJ/mol for larger water clusters. Previous reports on seismo-ionospheric coupling have suggested that select metal-ions M+, such as sodium and iron, are dragged by anomalous electric fields up to E-layer altitudes before earthquakes and are responsible for sporadic ionospheric metal-ion layers [Pulinets,1997 Adv.SpaceRes.,20,2173]. This report applies quantum chemical methods to calculate the geometries, energetics, thermochemistry and ionospheric abundances of a suite of solvated alkali and ionic transition metal clusters with up to six water molecules. Structural and energetic properties of ion-water clusters are calculated using Møller-Plesset perturbation theory (MP2) with a large number of different basis sets. Calculated solvation enthalpies for Na+, K+, Fe+ and Cu+ reported here are in excellent agreement with experimental mass spectrometric data. For instance, the calculated solvation enthalpy for groundstate 6D Fe+(H2O) is -108.9 kJ/mol and is in good agreement with the experimental value of -120±12 kJ/mol [Magnera,JACS,111,4100]. The subsequent hydration step toward Fe+(H2O)2, which is accompanied by a spin change to a 4A1 ground state, is exothermic by -198.0 kJ/mol. The experimental enthalpy ΔH1,2 for water attachment onto Fe+(H2O) is -170.7 [Marinelli, 1998,JACS,111,4101]. Interestingly, results from both this ab initio study and mass spectrometry demonstrate that Fe+ binds a second water molecule somewhat more strongly than the first one. The subsequent solvation steps asymptotically approach values of around -44 kJ/mol, showing a trend toward the bulk water limit. An analysis of calculated clustering equilibria K indicates that ionospheric metal ion-water cluster abundances are governed by the shifting balance between the temperature induced changes of K and water monomer abundances. Results from ab initio calculations presented here indicate that H2O attachment onto alkali and transition metals is a thermodynamically favorable process, such that hydrated metal clusters would form a significant ionospheric repository. |
Description | Poster: abstract no. NH31C-1130 |
Persistent Identifier | http://hdl.handle.net/10722/116979 |
DC Field | Value | Language |
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dc.contributor.author | Lemke, K | en_HK |
dc.contributor.author | Aitchison, J | en_HK |
dc.date.accessioned | 2010-09-26T06:55:48Z | - |
dc.date.available | 2010-09-26T06:55:48Z | - |
dc.date.issued | 2009 | en_HK |
dc.identifier.citation | The 2009 Fall Meeting of the American Geophysical Union (AGU), San Francisco, CA., 14-18 December 2009. | - |
dc.identifier.uri | http://hdl.handle.net/10722/116979 | - |
dc.description | Poster: abstract no. NH31C-1130 | - |
dc.description.abstract | Gas phase metal-ions form hydrated complexes, which have characteristic solvation enthalpies ranging from around -150kJ/mol for monohydrates to around -40kJ/mol for larger water clusters. Previous reports on seismo-ionospheric coupling have suggested that select metal-ions M+, such as sodium and iron, are dragged by anomalous electric fields up to E-layer altitudes before earthquakes and are responsible for sporadic ionospheric metal-ion layers [Pulinets,1997 Adv.SpaceRes.,20,2173]. This report applies quantum chemical methods to calculate the geometries, energetics, thermochemistry and ionospheric abundances of a suite of solvated alkali and ionic transition metal clusters with up to six water molecules. Structural and energetic properties of ion-water clusters are calculated using Møller-Plesset perturbation theory (MP2) with a large number of different basis sets. Calculated solvation enthalpies for Na+, K+, Fe+ and Cu+ reported here are in excellent agreement with experimental mass spectrometric data. For instance, the calculated solvation enthalpy for groundstate 6D Fe+(H2O) is -108.9 kJ/mol and is in good agreement with the experimental value of -120±12 kJ/mol [Magnera,JACS,111,4100]. The subsequent hydration step toward Fe+(H2O)2, which is accompanied by a spin change to a 4A1 ground state, is exothermic by -198.0 kJ/mol. The experimental enthalpy ΔH1,2 for water attachment onto Fe+(H2O) is -170.7 [Marinelli, 1998,JACS,111,4101]. Interestingly, results from both this ab initio study and mass spectrometry demonstrate that Fe+ binds a second water molecule somewhat more strongly than the first one. The subsequent solvation steps asymptotically approach values of around -44 kJ/mol, showing a trend toward the bulk water limit. An analysis of calculated clustering equilibria K indicates that ionospheric metal ion-water cluster abundances are governed by the shifting balance between the temperature induced changes of K and water monomer abundances. Results from ab initio calculations presented here indicate that H2O attachment onto alkali and transition metals is a thermodynamically favorable process, such that hydrated metal clusters would form a significant ionospheric repository. | - |
dc.language | eng | en_HK |
dc.publisher | American Geophysical Union (AGU) | - |
dc.relation.ispartof | AGU Fall Meeting 2009 | en_HK |
dc.subject | [0335] ATMOSPHERIC COMPOSITION AND STRUCTURE - Ion chemistry of the atmosphere | - |
dc.subject | [1011] GEOCHEMISTRY - Thermodynamics | - |
dc.subject | [2419] IONOSPHERE - Ion chemistry and composition | - |
dc.subject | [7223] SEISMOLOGY - Earthquake interaction, forecasting, and prediction | - |
dc.title | Metal-ion solvation and abundance in atmospheric media before strong earthquakes | en_HK |
dc.type | Conference_Paper | en_HK |
dc.identifier.email | Lemke, K: kono@hku.hk | en_HK |
dc.identifier.email | Aitchison, J: jona@hku.hk | en_HK |
dc.identifier.authority | Lemke, K=rp00729 | en_HK |
dc.identifier.authority | Aitchison, J=rp00658 | en_HK |
dc.description.nature | link_to_OA_fulltext | - |
dc.identifier.hkuros | 168746 | en_HK |
dc.publisher.place | United States | - |