Εξειδίκευση τύπου :	Άρθρο σε επιστημονικό περιοδικό
Τίτλος:	Structure and dynamics of Water-Smectite interfaces: Hydrogen bonding and the origin of the sharp O-Dw/O-Hw infrared band from molecular simulations
Δημιουργός/Συγγραφέας:	Szczerba M. Kuligiewicz A. Derkowski A. [EL] Γκιώνης, Βασίλης[EN] Gionis, Vassilis [EL] Χρυσικός, Γεώργιος Δ.[EN] Chryssikos, Georgios D. Kalinichev A.G.
Εκδότης:	Clay Minerals Society
Ημερομηνία:	2016
Γλώσσα:	Αγγλικά
ISSN:	0009-8604
DOI:	10.1346/CCMN.2016.0640409
Περίληψη:	Experimental studies have shown that a sharp, high-frequency IR band at ~3615 cm- 1 (in H2O form) and at ~2685 cm- 1 (in D2O form) is a common feature for all smectites, and its position correlates with layer charge. In order to explain the molecular origin of this band in terms of total layer charge, charge localization, as well as nature of interlayer cations influencing the position and intensity of this peak, a series of classical molecular dynamics (MD) simulations was performed for several smectite models. The smectite layers were described using a modified CLAYFF force field, where the intramolecular vibrations of H2O were described more accurately by the Toukan-Rahman potential. The power spectra of molecular vibrations of hydrogens were calculated for selected sub-sets of interlayer H2O to analyze quantitatively their contribution to the observed spectral features. The statistics of hydrogen bonds in the smectite interlayers were also analyzed to support the spectral calculations. The simulation results demonstrated clearly that only the H2O molecules in close proximity to the smectite surface are responsible for the sharp vibrational band observed. Other hypotheses for the possible origins of this band were considered carefully and eventually rejected. Two orientations of H2O molecules donating one or two H bonds to the basal oxygens of the smectite surface (monodentate and bidentate orientations, respectively) were observed. In both orientations, these H bonds are quite weak, pointing to a generally hydrophobic character of the smectite surface. Both orientations contributed to the highfrequency band, but the monodentate orientation provided the predominant contribution because surface H2O molecules in this orientation were much more abundant. In good agreement with experiment, only a small difference in the peak position was observed between smectites with different charge localization. The effect of the total layer charge, i.e. the red-shift for higher-charge smectites, was also confirmed. This shift arose from the decrease in the H-bonding distances of H2O in monodentate and bidentate orientation.
Τίτλος πηγής δημοσίευσης:	Clays and Clay Minerals
Τόμος/Κεφάλαιο:	64
Τεύχος:	4
Σελίδες:	452-471
Θεματική Κατηγορία:	[EL] Φυσική και θεωρητική χημεία[EN] Physical and theoretical chemistry [EL] Φασματοσκοπία[EN] Spectroscopy
Λέξεις-Κλειδιά:	Adsorbed water Clay-water interface Infrared spectroscopy Molecular dynamics Smectite
Αξιολόγηση από ομότιμους (peer reviewed):	Ναι
Κάτοχος πνευματικών δικαιωμάτων:	© 2016, Clays and Clay Minerals. All rights reserved.
Όροι και προϋποθέσεις δικαιωμάτων:	All Open Access, Green
Σημειώσεις:	2012/05/B/ST10/01948; EDF Energy; European Commission, EC; General Secretariat for Research and Technology, GSRT The present work was supported by the project ATLAB (FP7-REGPOT-2011-1 No. 285989) funded by the European Union. MS also acknowledges NCNNarodowe Centrum Nauki (grant 2012/05/B/ST10/01948), which provided IGS PAS with a highperformance computing server and also PLGRID infrastructure. AGK acknowledges the support of the industrial chair ??Storage and Disposal of Radioactive Waste at the Ecole des Mines de Nantes, funded by ANDRA, Areva, and EDF. VG and GDC acknowledge partial support from project KRHPIS 447963-Polynano (GSRT, TPCI-NHRF).
Εμφανίζεται στις συλλογές:	Ινστιτούτο Θεωρητικής και Φυσικής Χημείας (ΙΘΦΧ) - Επιστημονικό έργο