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Université de Fribourg

Tailoring the optical properties of lanthanide phosphors: prediction and characterization of the luminescence of Pr3+-doped LiYF4

Ramanantoanina, Harry ; Urland, Werner ; Herden, Benjamin ; Cimpoesu, Fanica ; Daul, Claude

In: Physical Chemistry Chemical Physics, 2015, vol. 17, no. 14, p. 9116–9125

We present a theoretical work detailing the electronic structure and the optical properties of (PrF₈)⁵⁻ embedded in LiYF₄, complementing the insight with data that are not available by experimental line. The local distortions due to the embedding of the lanthanide ion in the sites occupied in the periodic lattice by smaller yttrium centres, not detectable in regular X-ray analyses, are...

Université de Fribourg

Magnetic anisotropy in ‘scorpionate’ first-row transition-metal complexes: a theoretical investigation

Perić, Marko ; García-Fuente, Amador ; Zlatar, Matija ; Daul, Claude ; Stepanović, Stepan ; García-Fernández, Pablo ; Gruden-Pavlović, Maja

In: Chemistry – A European Journal, 2015, vol. 21, no. 9, p. 3716–3726

In this work we have analyzed in detail the magnetic anisotropy in a series of hydrotris(pyrazolyl)borate (Tp−) metal complexes, namely [VTpCl]+, [CrTpCl]+, [MnTpCl]+, [FeTpCl], [CoTpCl], and [NiTpCl], and their substituted methyl and tert-butyl analogues with the goal of observing the effect of the ligand field on the magnetic properties. In the [VTpCl]+, [CrTpCl]+, [CoTpCl], and [NiTpCl]...

Université de Fribourg

Photon cascade emission in Pr³⁺ doped fluorides with CaF₂ structure: Application of a model for its prediction

Herden, Benjamin ; García-Fuente, Amador ; Ramanantoanina, Harry ; Jüstel, Thomas ; Daul, Claude ; Urland, Werner

In: Chemical Physics Letters, 2015, vol. 620, p. 29–34

In this work, we predict and measure the optical behaviour of Pr³⁺ in different binary and ternary fluorides. We use a validated model based on Ligand Field Theory and Density Functional Theory to calculate the multiplet energy levels arising from the ground [Xe]4f² and excited [Xe]4f¹5d¹ electron configurations of Pr³⁺ in its chemical environment. Moreover, the luminescence spectra of...

Université de Fribourg

The theoretical account of the ligand field bonding regime and magnetic anisotropy in the DySc₂N@C₈₀ single ion magnet endohedral fullerene

Cimpoesu, Fanica ; Dragoe, Nita ; Ramanantoanina, Harry ; Urland, Werner ; Daul, Claude

In: Physical Chemistry Chemical Physics, 2014, vol. 16, no. 23, p. 11337–11348

Considering the DySc₂N@C₈₀ system as a prototype for Single Ion Magnets (SIMs) based on endohedral fullerenes, we present methodological advances and state-of-the art computations analysing the electronic structure and its relationship with the magnetic properties due to the Dy(III) ion. The results of the quantum chemical calculations are quantitatively decrypted in the framework of ligand...

Université de Fribourg

Ligand field density functional theory for the prediction of future domestic lighting

Ramanantoanina, Harry ; Urland, Werner ; García-Fuente, Amador ; Cimpoesu, Fanica ; Daul, Claude

In: Physical Chemistry Chemical Physics, 2014, vol. 16, no. 28, p. 14625–14634

We deal with the computational determination of the electronic structure and properties of lanthanide ions in complexes and extended structures having open-shell f and d configurations. Particularly, we present conceptual and methodological issues based on Density Functional Theory (DFT) enabling the reliable calculation and description of the f → d transitions in lanthanide doped phosphors. We...

Université de Fribourg

The angular overlap model extended for two-open-shell f and d electrons

Ramanantoanina, Harry ; Urland, Werner ; Cimpoesu, Fanica ; Daul, Claude

In: Physical Chemistry Chemical Physics, 2014, vol. 16, no. 24, p. 12282–12290

We discuss the applicability of the Angular Overlap Model (AOM) to evaluate the electronic structure of lanthanide compounds, which are currently the subject of incredible interest in the field of luminescent materials. The functioning of phosphors is well established by the f–d transitions, which requires the investigation of both the ground 4fn and excited 4fn−15d1 electron configurations...

Université de Fribourg

Ligand field density functional theory calculation of the 4f² → 4f¹5d¹ transitions in the quantum cutter Cs₂KYF₆:Pr³⁺

Ramanantoanina, Harry ; Urland, Werner ; Cimpoesu, Fanica ; Daul, Claude

In: Physical Chemistry Chemical Physics, 2013, vol. 15, no. 33, p. 13902–13910

Herein we present a Ligand Field Density Functional Theory (LFDFT) based methodology for the analysis of the 4fⁿ → 4fⁿ⁻¹5d¹ transitions in rare earth compounds and apply it for the characterization of the 4f² → 4f¹5d¹ transitions in the quantum cutter Cs₂KYF₆:Pr³⁺ with the elpasolite structure type. The methodological advances are relevant for the analysis and prospection of...

Université de Fribourg

Benzo[1,2-b:4,5-b′]difuran-based sensitizers for dye-sensitized solar cells

Li, Hui ; Yi, Chenyi ; Moussi, Sofiane ; Liu, Shi-Xia ; Daul, Claude ; Grätzel, Michael ; Decurtins, Silvio

In: RSC Advances, 2013, vol. 3, no. 43, p. 19798–19801

Two BDF-based organic sensitizers, as first examples for their use in dye-sensitized solar cells, are prepared and characterized. They yield promising power conversion efficiencies of up to 5.5% and high open circuit voltages up to 0.82 V. This work demonstrates that the BDF chromophore acts as an effective donor in organic sensitizers.

Université de Fribourg

Spherical aromaticity of Jahn–Teller active fullerene ions

Perić, Marko ; Andjelković, Ljubica ; Zlatar, Matija ; Nikolić, Aleksandar S. ; Daul, Claude ; Gruden-Pavlović, Maja

In: Monatshefte für Chemie - Chemical Monthly, 2013, vol. 144, no. 6, p. 817–823

Density functional theory was applied to compute the nucleus-independent chemical shifts of fullerene (C₆₀), the fullerene ion C₆₀ ¹⁰⁺, and the Jahn–Teller active fullerene anion C₆₀ ⁻ and cation C₆₀ ⁺. Positioning a ³He nucleus inside the cage of each of these fullerene species facilitates investigations of the substantial differences among them, ³He NMR chemical...

Université de Fribourg

The choice of the exchange-correlation functional for the determination of the jahn–teller parameters by the density functional theory

Andjelković, Ljubica ; Gruden-Pavlović, Maja ; Daul, Claude ; Zlatar, Matija

In: International Journal of Quantum Chemistry, 2012, p. -

The Jahn–Teller (JT) parameters for small, aromatic, organic radicals, CnHn (n = 4–7), bis(cyclopentadienyl)cobalt(II) (cobaltocene), a sodium cluster (Na3), a silver cluster (Ag3), the hexaflurocuprate(II) ion ([CuF6]4−), and tris(acetylacetonato)manganese(III) ([Mn(acac)3]) have been evaluated by the means of the multideterminantal density functional theory using the most common...