Merve Yesilbas defended her Ph.D. thesis on April 13 th.

 

 

 

 

 

 

 

 

 

 

from left to right:   Staffan Sjöberg, Jan Pettersson (Gothenburg University), JF Boily, Merve Yesilbas, Grégory Lefèvre (CNRS-Paris)

 

Check out link here: Yesilbas Press Release

Mark Ramabaran has joined the Ohlin group as a PhD student. He will be looking at the solution chemistry of polyoxometalates and their use as models for reactions on extended metal oxide surfaces.

Merve nailed her Ph.D. Thesis “Thin Water and Films on Minerals: A Molecular Level Study” on March 23rd.

She will defend her thesis on April 13th at Umeå University (info here).

Opponent: Grégory Lefèvre (Chime ParisTech)

Evaluation Committee: Stina Jansson (Chemistry, UmU), Jan Pettersson (University of Gothenburg), Alexandr Talyzin (Physics, UmU)

Wei is a visiting Ph.D student from Khalil Hanna‘s group (Rennes).
During her 6-month stay, she will be studying water vapour binding on
organically-coated minerals with JF Boily.

¹⁷O NMR as a Tool in Discrete Metal Oxide Cluster Chemistry

in Annual Reports on NMR Spectroscopy. Link.

C. André Ohlin, William H. Casey

Abstract: This chapter covers recent developments in ¹⁷O NMR spectroscopy as applied to discrete metal oxide clusters, particularly in the context of their use as models in geochemistry and catalysis. Dynamic ¹⁷O NMR methods based on the McConnell–Bloch equations are explored in depth, and recent advances are reviewed. High-pressure NMR methods are also discussed and reviewed, as are recent developments in the use of density functional theory in the computation of ¹⁷O NMR shifts in polyoxometalates. The emphasis of the chapter is on the new developments that promise to reinvigorate ¹⁷O NMR as a central tool in the study of aqueous chemical kinetics, with the most urgent challenges being understanding the rates of isotopic substitution into bridging oxygens in clusters.

 

A collaboration with Changxun Xu and Mats Åström of Linnaeus University with JF Boily and Andrey Shchukarev

You can find the article here

Authored by Merve Yesilbas, Cheng Choo (Nikki) Lee, and Jean-François Boily

We thank the Umeå Core Facility for Electron Microscopy (UCEM) for a great collaboration!

You can find the link here.

Computational Prediction of Mg-Isotope Fractionation Between Aqueous [Mg(OH₂)₆]²⁺ and Brucite

Geochim. Cosmochim. Acta., Accepted. Link.

Christopher A. Colla, W. H. Casey, C. André Ohlin

Abstract: The fractionation factor in the magnesium-isotope fractionation between aqueous solutions of magnesium and brucite remarkably changes sign with increasing temperature, as uncovered by recent experiments.  To understand this behavior, the Reduced Partition Function Ratios and isotopic fractionation factors (Δ^26/24Mg_{brucite-Mg(aq)}) are calculated using molecular models of aqueous [Mg(OH₂)₆]²⁺ and the mineral brucite at increasing levels of density functional theory.  The calculations were carried out on the [Mg(OH₂)₆]²⁺·12H₂O cluster, along with different Pauling-bond-strength-conserving models of the mineral lattice of brucite. Three conclusions were reached: i) all of the calculations overestimate <Mg-O> bond distances in the aqua ion complex relative to Tutton’s salts; ii) the calculations predict that brucite at 298.15 K is always enriched in the heavy isotope, in contrast with experimental observations; iii) the temperature dependencies of Wimpenny et al. (2014) and Li et al. (2014) could only be achieved by fixing the <Mg-O> bond distances in the [Mg(OH₂)₆]²⁺·12H₂O cluster to values close to those observed in crystals that trap the hydrated ion. Read more.

 

A collaboration between JF Boily and Glenn Waychunas (LBNL). Paper is here!