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Mechanisms of Dipolar Ortho/Para-H2O Conversion in Ice

Buntkowsky, Gerd ; Limbach, Hans-Heinrich ; Walaszek, B. ; Adamczyk, Anna ; Xu, Y. ; Breitzke, H. ; Schweitzer, A. ; Gutmann, T. ; Wächtler, Maria ; Amadeu, N. ; Tietze, D. ; Chaudret, Bruno (2021)
Mechanisms of Dipolar Ortho/Para-H2O Conversion in Ice.
In: Zeitschrift für Physikalische Chemie, 222 (7)
doi: 10.26083/tuprints-00019689
Artikel, Zweitveröffentlichung, Verlagsversion

Kurzbeschreibung (Abstract)

In this paper a possible explanation for an unexpected ortho.para-water ratio in the gas clouds of comets is given. The description is based on the quantum-mechanical density matrix formalism and the spin temperature concept. Only the nuclear spin system is treated quantum-mechanically. Employing the model of a four spin system, created by two nearest neighbour water molecules, spin eigenstates and their dynamics under the influence of their mutual dipolar interactions are studied. It is shown that a fast conversion between ortho- and para-states occurs on a msec time scale, caused by the intermolecular homonuclear magnetic dipolar interaction. Moreover the spin eigenstates of water in an ice crystal are determined by magnetic dipolar interactions and are not given by normal ortho- and para-H₂O states of gaseous water. As a result of this the spin temperature of gaseous water evaporated from ice depends strongly on its evaporation history and the ortho.para-ratio of water molecules are only an indirect measure of the temperature of ice crystals from where they descend. This result could explain the unexpected experimentally observed ortho.para-ratios in the clouds of comets.

Typ des Eintrags: Artikel
Erschienen: 2021
Autor(en): Buntkowsky, Gerd ; Limbach, Hans-Heinrich ; Walaszek, B. ; Adamczyk, Anna ; Xu, Y. ; Breitzke, H. ; Schweitzer, A. ; Gutmann, T. ; Wächtler, Maria ; Amadeu, N. ; Tietze, D. ; Chaudret, Bruno
Art des Eintrags: Zweitveröffentlichung
Titel: Mechanisms of Dipolar Ortho/Para-H2O Conversion in Ice
Sprache: Englisch
Publikationsjahr: 2021
Verlag: De Gruyter
Titel der Zeitschrift, Zeitung oder Schriftenreihe: Zeitschrift für Physikalische Chemie
Jahrgang/Volume einer Zeitschrift: 222
(Heft-)Nummer: 7
DOI: 10.26083/tuprints-00019689
URL / URN: https://tuprints.ulb.tu-darmstadt.de/19689
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Herkunft: Zweitveröffentlichungsservice
Kurzbeschreibung (Abstract):

In this paper a possible explanation for an unexpected ortho.para-water ratio in the gas clouds of comets is given. The description is based on the quantum-mechanical density matrix formalism and the spin temperature concept. Only the nuclear spin system is treated quantum-mechanically. Employing the model of a four spin system, created by two nearest neighbour water molecules, spin eigenstates and their dynamics under the influence of their mutual dipolar interactions are studied. It is shown that a fast conversion between ortho- and para-states occurs on a msec time scale, caused by the intermolecular homonuclear magnetic dipolar interaction. Moreover the spin eigenstates of water in an ice crystal are determined by magnetic dipolar interactions and are not given by normal ortho- and para-H₂O states of gaseous water. As a result of this the spin temperature of gaseous water evaporated from ice depends strongly on its evaporation history and the ortho.para-ratio of water molecules are only an indirect measure of the temperature of ice crystals from where they descend. This result could explain the unexpected experimentally observed ortho.para-ratios in the clouds of comets.

Status: Verlagsversion
URN: urn:nbn:de:tuda-tuprints-196896
Zusätzliche Informationen:

Keywords: Ortho/Para-Water, Spin Temperature, Dipolar Interaction, Comets, Ice

Sachgruppe der Dewey Dezimalklassifikatin (DDC): 500 Naturwissenschaften und Mathematik > 540 Chemie
Fachbereich(e)/-gebiet(e): 07 Fachbereich Chemie
07 Fachbereich Chemie > Eduard Zintl-Institut > Fachgebiet Physikalische Chemie
Hinterlegungsdatum: 01 Okt 2021 11:32
Letzte Änderung: 04 Okt 2021 06:06
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