Research


Our main interest is the design of materials using anion substitution by hydride, and the synthesis and properties of rare earth doped solid state materials.

Optical and vibrational spectroscopy, especially photoluminescence spectroscopy, are used in order to gain a better understanding of the materials‘ properties. Rare earth ions serve as very sensitive probes for the local environment.

Different preparation methods, such as solid state reactions or reactions under gas pressure are applied. For structural characterization, we take advantage of combined X-ray and neutron diffraction studies.


Highlights

 

Reprinted  with permission from N. Kunkel, Ph. Goldner, „Recent Advances in Rare Earth Doped Inorganic Crystalline Materials for Quantum Information Processing“ Z. Anorg. Allg. Chem. 2017, DOI: 10.1002/zaac.201700425. Copyright 2017 Wiley-VCH.

Review on recent developments in the field of quantum information processing using rare earth doped systems.

December 20, 2017

N. Kunkel, Ph. Goldner, „Recent Advances in Rare Earth Doped Inorganic Crystalline
Materials for Quantum Information Processing“ Z. Anorg. Allg. Chem.2018, 644, 66-76, DOI: 10.1002/zaac.201700425.

Our review article was chosen for the front cover of Z. Anorg. Allg. Chem. 2/2018.

 Reprinted (adapted) with permission from N. Kunkel, Atul D. Sontakke, S. Kohaut, B. Viana, P. Dorenbos, „Thermally simulated luminescence and first-principle study of defect configurations in the perovskite-type hydrides LiMH3:Eu2+ (M = Sr, Ba) and the corresponding deuterides,“ J. Phys. Chem. C 2016, 120, 29414. Copyright 2016 American Chemical Society.

Thermally stimulated luminescence in Eu2+-doped hydrides

December 2, 2016

Thermally stimulated luminescence emission is studied for the first time in Eu2+-doped hydrides, an exemplary a scheme with the localization of divalent and trivalent lanthanide 4f and 5d levels is proposed and defects are dicuscussed.

N. Kunkel, Atul D. Sontakke, S. Kohaut, B. Viana, P. Dorenbos, „Thermally simulated luminescence and first-principle study of defect configurations in the perovskite-type hydrides LiMH3:Eu2+ (M = Sr, Ba) and the corresponding deuterides,“ J. Phys. Chem. C 2016, 120, 29414.

 Reprinted (adapted) with permission from : N. Kunkel, J. Bartholomew, S. Welinski, A. Ferrier, A. Ikesue, and P. Goldner, „Dephasing mechanisms of optical transitions in rare-earth-doped transparent ceramics,“ Phys. Rev. B 2016, 94, 184301.
C
opyright 2016 by the American Physical Society.

Dephasing Mechanisms in Rare Earth Doped Transparent Ceramics

November 01, 2016

We analyze dephasing mechanisms that broaden the optical transitions of rare-earth ions in randomly oriented transparent ceramics. The study examines the narrow 7F05D0 transition of Eu3+ dopants in a series of Y2O3 ceramic samples prepared under varying conditions. We characterize the temperature and magnetic field dependence of the homogeneous linewidth, as well as long-term spectral diffusion on time scales up to 1 s. The results highlight significant differences between samples with differing thermal treatments and Zr4+ additive concentrations. By minimizing the broadening due to the different defect centers, linewidths of the order of 4 kHz are achieved for all samples.

N. Kunkel, J. Bartholomew, S. Welinski, A. Ferrier, A. Ikesue, and P. Goldner, „Dephasing mechanisms of optical transitions in rare-earth-doped transparent ceramics,“ Phys. Rev. B 2016, 94, 184301.

 Reprinted (adapted) with permission from N. Kunkel, J. Bartholomew, L. Binet, A. Ikesue, and P. Goldner, “High-Resolution Optical Line Width Measurements as a Material Characterization Tool,” J. Phys. Chem. C, 2016, 120, no. 25,  13725–13731.
Copyright 2016 American Chemical Society.

High-Resolution Optical Line Width Measurements as a Material Characterization Tool

June 1, 2016

By comparing the results from coherent and incoherent optical spectroscopy in europium doped transparent ceramics with other characterization methods, we show that optical techniques can deliver supplementary information about the local environment (defects, micro-structural strain) of the activator ions in materials. Thus, high-resolution spectroscopy may be of interest for the investigation of a wider range of rare earth doped optical materials beyond materials studied for quantum information technology.

N. Kunkel, J. Bartholomew, L. Binet, A. Ikesue, and P. Goldner, “High-Resolution Optical Line Width Measurements as a Material Characterization Tool,” J. Phys. Chem. C, 2016, 120, no. 25,  13725–13731.


Collaborations

Prof. Dr. Pieter Dorenbos, TU Delft
Prof. Dr. Antti Karttunen, Aalto University
Prof. Dr. Andries Meijerink, Utrecht University
Prof. Dr. Andreas Pöppl,  Leipzig University
Prof. Dr. Adlane Sayede, Université d’Artois, Lens – CNRS
Dr. Bruno Viana, Chimie ParisTech – CNRS

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Funding

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Fonds der Chemischen Industrie

TU Munich Junior Fellow Program

Dr.-Ing.-Leonard-Lorenz-Foundation

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Deutsche Forschungsgemeinschaft

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International Research Group IRTG 2022 „ATUMS“ – Alberta/Technical University of Munich International Graduate School

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BayFrance, former Bayerisch-Französisches Hochschulzentrum (BFHZ)

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Erasmus