---
_id: '65316'
abstract:
- lang: eng
  text: Metasurfaces are powerful tools for manipulating light using small structures
    on the nanoscale. In most metasurfaces, near-field couplings are treated as being
    unfavorable perturbations. Here, we experimentally investigate a structure consisting
    of sinusoidally modulated silicon waveguides where near-field coupling of local
    resonances leads to negative coupling, i.e., a negative coupling constant. This
    gives rise to wave-vector-dependent eigenstates of elliptical, linear, and circular
    polarizations. In particular, fully circular polarization states are not only
    present at a single point in momentum space (k-space) but also along a line. This
    circular polarization line, as well as a linear polarization line, emanates from
    a polarization degeneracy at the Dirac point. We experimentally validate the existence
    of these eigenstates and demonstrate the energy-, polarization-, and wave vector
    dependence of this metasurface as well as its sensitivity to fabrication tolerances.
    By tuning the incident k-vector, certain polarization-energy eigenstates are strongly
    reflected, allowing for uses in angle-tunable polarization filters and light sources.
author:
- first_name: Helene
  full_name: Wetter, Helene
  last_name: Wetter
- first_name: Jan
  full_name: Wingenbach, Jan
  id: '69187'
  last_name: Wingenbach
- first_name: Falk
  full_name: Rehberg, Falk
  last_name: Rehberg
- first_name: Wenlong
  full_name: Gao, Wenlong
  last_name: Gao
- first_name: Stefan
  full_name: Schumacher, Stefan
  id: '27271'
  last_name: Schumacher
  orcid: 0000-0003-4042-4951
- first_name: Thomas
  full_name: Zentgraf, Thomas
  id: '30525'
  last_name: Zentgraf
  orcid: 0000-0002-8662-1101
citation:
  ama: Wetter H, Wingenbach J, Rehberg F, Gao W, Schumacher S, Zentgraf T. Polarization-
    and Wave-Vector Selective Optical Metasurface with Near-Field Coupling. <i>ACS
    Photonics</i>. 2026;13:2128-2133. doi:<a href="https://doi.org/10.1021/acsphotonics.5c02865">10.1021/acsphotonics.5c02865</a>
  apa: Wetter, H., Wingenbach, J., Rehberg, F., Gao, W., Schumacher, S., &#38; Zentgraf,
    T. (2026). Polarization- and Wave-Vector Selective Optical Metasurface with Near-Field
    Coupling. <i>ACS Photonics</i>, <i>13</i>, 2128–2133. <a href="https://doi.org/10.1021/acsphotonics.5c02865">https://doi.org/10.1021/acsphotonics.5c02865</a>
  bibtex: '@article{Wetter_Wingenbach_Rehberg_Gao_Schumacher_Zentgraf_2026, title={Polarization-
    and Wave-Vector Selective Optical Metasurface with Near-Field Coupling}, volume={13},
    DOI={<a href="https://doi.org/10.1021/acsphotonics.5c02865">10.1021/acsphotonics.5c02865</a>},
    journal={ACS Photonics}, publisher={American Chemical Society (ACS)}, author={Wetter,
    Helene and Wingenbach, Jan and Rehberg, Falk and Gao, Wenlong and Schumacher,
    Stefan and Zentgraf, Thomas}, year={2026}, pages={2128–2133} }'
  chicago: 'Wetter, Helene, Jan Wingenbach, Falk Rehberg, Wenlong Gao, Stefan Schumacher,
    and Thomas Zentgraf. “Polarization- and Wave-Vector Selective Optical Metasurface
    with Near-Field Coupling.” <i>ACS Photonics</i> 13 (2026): 2128–33. <a href="https://doi.org/10.1021/acsphotonics.5c02865">https://doi.org/10.1021/acsphotonics.5c02865</a>.'
  ieee: 'H. Wetter, J. Wingenbach, F. Rehberg, W. Gao, S. Schumacher, and T. Zentgraf,
    “Polarization- and Wave-Vector Selective Optical Metasurface with Near-Field Coupling,”
    <i>ACS Photonics</i>, vol. 13, pp. 2128–2133, 2026, doi: <a href="https://doi.org/10.1021/acsphotonics.5c02865">10.1021/acsphotonics.5c02865</a>.'
  mla: Wetter, Helene, et al. “Polarization- and Wave-Vector Selective Optical Metasurface
    with Near-Field Coupling.” <i>ACS Photonics</i>, vol. 13, American Chemical Society
    (ACS), 2026, pp. 2128–33, doi:<a href="https://doi.org/10.1021/acsphotonics.5c02865">10.1021/acsphotonics.5c02865</a>.
  short: H. Wetter, J. Wingenbach, F. Rehberg, W. Gao, S. Schumacher, T. Zentgraf,
    ACS Photonics 13 (2026) 2128–2133.
date_created: 2026-04-02T07:25:30Z
date_updated: 2026-04-20T05:09:57Z
department:
- _id: '15'
- _id: '230'
- _id: '289'
- _id: '623'
doi: 10.1021/acsphotonics.5c02865
external_id:
  arxiv:
  - '2512.14452'
intvolume: '        13'
keyword:
- metasurface
- waveguides
- Dirac point
- polarization
- negative coupling
language:
- iso: eng
main_file_link:
- url: https://pubs.acs.org/doi/10.1021/acsphotonics.5c02865
page: 2128-2133
publication: ACS Photonics
publication_identifier:
  issn:
  - 2330-4022
  - 2330-4022
publication_status: published
publisher: American Chemical Society (ACS)
quality_controlled: '1'
status: public
title: Polarization- and Wave-Vector Selective Optical Metasurface with Near-Field
  Coupling
type: journal_article
user_id: '30525'
volume: 13
year: '2026'
...
---
_id: '63988'
abstract:
- lang: eng
  text: This concept summarizes recent advances in development and application of
    DNP enhanced multinuclear solid-state NMR to study the molecular structure and
    surface functionalization of cellulose and paper-based materials. Moreover, a
    novel application is presented where DNP enhanced 13C and 15N solid-state NMR
    is used to identify structure moieties formed by cross-linking of hydroxypropyl
    cellulose. Given these two aspects of this concept-type of article, we thus combine
    both, a review on recent findings already published and unpublished recent data
    that complement the existing knowledge in the field of characterization of functional
    lignocellulosic materials by DNP enhanced solid-state NMR.
author:
- first_name: Mark V.
  full_name: Höfler, Mark V.
  last_name: Höfler
- first_name: Jonas
  full_name: Lins, Jonas
  last_name: Lins
- first_name: David
  full_name: Seelinger, David
  last_name: Seelinger
- first_name: Lukas
  full_name: Pachernegg, Lukas
  last_name: Pachernegg
- first_name: Timmy
  full_name: Schäfer, Timmy
  last_name: Schäfer
- first_name: Stefan
  full_name: Spirk, Stefan
  last_name: Spirk
- first_name: Markus
  full_name: Biesalski, Markus
  last_name: Biesalski
- first_name: Torsten
  full_name: Gutmann, Torsten
  id: '118165'
  last_name: Gutmann
citation:
  ama: Höfler MV, Lins J, Seelinger D, et al. DNP enhanced solid-state NMR – A powerful
    tool to address the surface functionalization of cellulose/paper derived materials.
    <i>Journal of Magnetic Resonance Open</i>. 2024;21:100163. doi:<a href="https://doi.org/10.1016/j.jmro.2024.100163">10.1016/j.jmro.2024.100163</a>
  apa: Höfler, M. V., Lins, J., Seelinger, D., Pachernegg, L., Schäfer, T., Spirk,
    S., Biesalski, M., &#38; Gutmann, T. (2024). DNP enhanced solid-state NMR – A
    powerful tool to address the surface functionalization of cellulose/paper derived
    materials. <i>Journal of Magnetic Resonance Open</i>, <i>21</i>, 100163. <a href="https://doi.org/10.1016/j.jmro.2024.100163">https://doi.org/10.1016/j.jmro.2024.100163</a>
  bibtex: '@article{Höfler_Lins_Seelinger_Pachernegg_Schäfer_Spirk_Biesalski_Gutmann_2024,
    title={DNP enhanced solid-state NMR – A powerful tool to address the surface functionalization
    of cellulose/paper derived materials}, volume={21}, DOI={<a href="https://doi.org/10.1016/j.jmro.2024.100163">10.1016/j.jmro.2024.100163</a>},
    journal={Journal of Magnetic Resonance Open}, author={Höfler, Mark V. and Lins,
    Jonas and Seelinger, David and Pachernegg, Lukas and Schäfer, Timmy and Spirk,
    Stefan and Biesalski, Markus and Gutmann, Torsten}, year={2024}, pages={100163}
    }'
  chicago: 'Höfler, Mark V., Jonas Lins, David Seelinger, Lukas Pachernegg, Timmy
    Schäfer, Stefan Spirk, Markus Biesalski, and Torsten Gutmann. “DNP Enhanced Solid-State
    NMR – A Powerful Tool to Address the Surface Functionalization of Cellulose/Paper
    Derived Materials.” <i>Journal of Magnetic Resonance Open</i> 21 (2024): 100163.
    <a href="https://doi.org/10.1016/j.jmro.2024.100163">https://doi.org/10.1016/j.jmro.2024.100163</a>.'
  ieee: 'M. V. Höfler <i>et al.</i>, “DNP enhanced solid-state NMR – A powerful tool
    to address the surface functionalization of cellulose/paper derived materials,”
    <i>Journal of Magnetic Resonance Open</i>, vol. 21, p. 100163, 2024, doi: <a href="https://doi.org/10.1016/j.jmro.2024.100163">10.1016/j.jmro.2024.100163</a>.'
  mla: Höfler, Mark V., et al. “DNP Enhanced Solid-State NMR – A Powerful Tool to
    Address the Surface Functionalization of Cellulose/Paper Derived Materials.” <i>Journal
    of Magnetic Resonance Open</i>, vol. 21, 2024, p. 100163, doi:<a href="https://doi.org/10.1016/j.jmro.2024.100163">10.1016/j.jmro.2024.100163</a>.
  short: M.V. Höfler, J. Lins, D. Seelinger, L. Pachernegg, T. Schäfer, S. Spirk,
    M. Biesalski, T. Gutmann, Journal of Magnetic Resonance Open 21 (2024) 100163.
date_created: 2026-02-07T15:46:32Z
date_updated: 2026-02-17T16:16:40Z
doi: 10.1016/j.jmro.2024.100163
extern: '1'
intvolume: '        21'
keyword:
- solid-state nmr
- dynamic nuclear polarization
- Hydroxypropyl cellulose
- Selective enhancement
- Spin labelling
language:
- iso: eng
page: '100163'
publication: Journal of Magnetic Resonance Open
status: public
title: DNP enhanced solid-state NMR – A powerful tool to address the surface functionalization
  of cellulose/paper derived materials
type: journal_article
user_id: '100715'
volume: 21
year: '2024'
...
---
_id: '63974'
abstract:
- lang: eng
  text: A versatile strategy for synthesizing tailored peptide based biradicals is
    presented. By labeling the protected amino acid hydroxyproline with PROXYL via
    the OH functionality and using this building block in solid phase peptide synthesis
    (SPPS), the obtained peptides become polarization agents for DNP enhanced solid-state
    NMR in biotolerant media. To analyze the effect of the radical position on the
    enhancement factor, three different biradicals are synthesized. The PROXYL spin-label
    is inserted in a collagen inspired artificial peptide sequence by binding through
    the OH group of the hydroxyproline moieties at specific position in the chain.
    This labeling strategy is universally applicable for any hydroxyproline position
    in a peptide sequence since solid-phase peptide synthesis is used to insert the
    building block. High performance liquid chromatography (HPLC) and mass spectrometry
    (MS) analyses show the successful introduction of the spin label in the peptide
    chain and electron paramagnetic resonance (EPR) spectroscopy confirms its activity.
    Dynamic nuclear polarization (DNP) enhanced solid-state nuclear magnetic resonance
    (NMR) experiments performed on frozen aqueous glycerol-d8 solutions containing
    these peptide radicals show significantly higher enhancement factors of up to
    45 in 1H→13C cross polarization magic angle spinning (CP MAS) experiments compared
    to an analogous mono-radical peptide including this building block (ε ≈ 14). Compared
    to commercial biradicals such as AMUPol for which enhancement factors {\textgreater}
    100 have been obtained in the past and which have been optimized in their structure,
    the obtained enhancement up to 45 for our biradicals presents a significant progress
    in radical design.
author:
- first_name: Kevin
  full_name: Herr, Kevin
  last_name: Herr
- first_name: Mark V.
  full_name: Höfler, Mark V.
  last_name: Höfler
- first_name: Henrike
  full_name: Heise, Henrike
  last_name: Heise
- first_name: Fabien
  full_name: Aussenac, Fabien
  last_name: Aussenac
- first_name: Felix
  full_name: Kornemann, Felix
  last_name: Kornemann
- first_name: David
  full_name: Rosenberger, David
  last_name: Rosenberger
- first_name: Martin
  full_name: Brodrecht, Martin
  last_name: Brodrecht
- first_name: Marcos
  full_name: Oliveira, Marcos
  last_name: Oliveira
- first_name: Gerd
  full_name: Buntkowsky, Gerd
  last_name: Buntkowsky
- first_name: Torsten
  full_name: Gutmann, Torsten
  id: '118165'
  last_name: Gutmann
citation:
  ama: Herr K, Höfler MV, Heise H, et al. Biradicals based on PROXYL containing building
    blocks for efficient dynamic nuclear polarization in biotolerant media. <i>Journal
    of Magnetic Resonance Open</i>. 2024;20:100152. doi:<a href="https://doi.org/10.1016/j.jmro.2024.100152">10.1016/j.jmro.2024.100152</a>
  apa: Herr, K., Höfler, M. V., Heise, H., Aussenac, F., Kornemann, F., Rosenberger,
    D., Brodrecht, M., Oliveira, M., Buntkowsky, G., &#38; Gutmann, T. (2024). Biradicals
    based on PROXYL containing building blocks for efficient dynamic nuclear polarization
    in biotolerant media. <i>Journal of Magnetic Resonance Open</i>, <i>20</i>, 100152.
    <a href="https://doi.org/10.1016/j.jmro.2024.100152">https://doi.org/10.1016/j.jmro.2024.100152</a>
  bibtex: '@article{Herr_Höfler_Heise_Aussenac_Kornemann_Rosenberger_Brodrecht_Oliveira_Buntkowsky_Gutmann_2024,
    title={Biradicals based on PROXYL containing building blocks for efficient dynamic
    nuclear polarization in biotolerant media}, volume={20}, DOI={<a href="https://doi.org/10.1016/j.jmro.2024.100152">10.1016/j.jmro.2024.100152</a>},
    journal={Journal of Magnetic Resonance Open}, author={Herr, Kevin and Höfler,
    Mark V. and Heise, Henrike and Aussenac, Fabien and Kornemann, Felix and Rosenberger,
    David and Brodrecht, Martin and Oliveira, Marcos and Buntkowsky, Gerd and Gutmann,
    Torsten}, year={2024}, pages={100152} }'
  chicago: 'Herr, Kevin, Mark V. Höfler, Henrike Heise, Fabien Aussenac, Felix Kornemann,
    David Rosenberger, Martin Brodrecht, Marcos Oliveira, Gerd Buntkowsky, and Torsten
    Gutmann. “Biradicals Based on PROXYL Containing Building Blocks for Efficient
    Dynamic Nuclear Polarization in Biotolerant Media.” <i>Journal of Magnetic Resonance
    Open</i> 20 (2024): 100152. <a href="https://doi.org/10.1016/j.jmro.2024.100152">https://doi.org/10.1016/j.jmro.2024.100152</a>.'
  ieee: 'K. Herr <i>et al.</i>, “Biradicals based on PROXYL containing building blocks
    for efficient dynamic nuclear polarization in biotolerant media,” <i>Journal of
    Magnetic Resonance Open</i>, vol. 20, p. 100152, 2024, doi: <a href="https://doi.org/10.1016/j.jmro.2024.100152">10.1016/j.jmro.2024.100152</a>.'
  mla: Herr, Kevin, et al. “Biradicals Based on PROXYL Containing Building Blocks
    for Efficient Dynamic Nuclear Polarization in Biotolerant Media.” <i>Journal of
    Magnetic Resonance Open</i>, vol. 20, 2024, p. 100152, doi:<a href="https://doi.org/10.1016/j.jmro.2024.100152">10.1016/j.jmro.2024.100152</a>.
  short: K. Herr, M.V. Höfler, H. Heise, F. Aussenac, F. Kornemann, D. Rosenberger,
    M. Brodrecht, M. Oliveira, G. Buntkowsky, T. Gutmann, Journal of Magnetic Resonance
    Open 20 (2024) 100152.
date_created: 2026-02-07T15:42:00Z
date_updated: 2026-02-17T16:17:22Z
doi: 10.1016/j.jmro.2024.100152
extern: '1'
intvolume: '        20'
keyword:
- solid-state nmr
- dynamic nuclear polarization
- peptides
- Biradicals
- Spin labeling
language:
- iso: eng
page: '100152'
publication: Journal of Magnetic Resonance Open
status: public
title: Biradicals based on PROXYL containing building blocks for efficient dynamic
  nuclear polarization in biotolerant media
type: journal_article
user_id: '100715'
volume: 20
year: '2024'
...
---
_id: '63970'
abstract:
- lang: eng
  text: Abstract Recent advances in solid-state nuclear magnetic resonance (NMR) spectroscopy,
    combined with dynamic nuclear polarization (DNP), quantum chemical DFT calculations,
    and gas-phase NMR spectroscopy investigating the structure and reactivity of heterogeneous
    catalysts are reviewed. The investigated catalysts range from classical mononuclear
    catalysts, like immobilized derivates of Wilkinson’s catalysts over binuclear
    catalysts such as the dirhodium paddlewheel catalyst to catalytic nanoparticles,
    employing various support materials, such as mesoporous silica gels, coordination
    polymers, and biomaterials such as cellulose.
author:
- first_name: Nadia
  full_name: Haro Mares, Nadia
  last_name: Haro Mares
- first_name: Millena
  full_name: Logrado, Millena
  last_name: Logrado
- first_name: Jan
  full_name: Kergassner, Jan
  last_name: Kergassner
- first_name: Bingyu
  full_name: Zhang, Bingyu
  last_name: Zhang
- first_name: Torsten
  full_name: Gutmann, Torsten
  id: '118165'
  last_name: Gutmann
- first_name: Gerd
  full_name: Buntkowsky, Gerd
  last_name: Buntkowsky
citation:
  ama: Haro Mares N, Logrado M, Kergassner J, Zhang B, Gutmann T, Buntkowsky G. Solid-State
    NMR of Heterogeneous Catalysts. <i>ChemCatChem</i>. Published online 2024:e202401159.
    doi:<a href="https://doi.org/10.1002/cctc.202401159">10.1002/cctc.202401159</a>
  apa: Haro Mares, N., Logrado, M., Kergassner, J., Zhang, B., Gutmann, T., &#38;
    Buntkowsky, G. (2024). Solid-State NMR of Heterogeneous Catalysts. <i>ChemCatChem</i>,
    e202401159. <a href="https://doi.org/10.1002/cctc.202401159">https://doi.org/10.1002/cctc.202401159</a>
  bibtex: '@article{Haro Mares_Logrado_Kergassner_Zhang_Gutmann_Buntkowsky_2024, title={Solid-State
    NMR of Heterogeneous Catalysts}, DOI={<a href="https://doi.org/10.1002/cctc.202401159">10.1002/cctc.202401159</a>},
    journal={ChemCatChem}, publisher={John Wiley &#38; Sons, Ltd}, author={Haro Mares,
    Nadia and Logrado, Millena and Kergassner, Jan and Zhang, Bingyu and Gutmann,
    Torsten and Buntkowsky, Gerd}, year={2024}, pages={e202401159} }'
  chicago: Haro Mares, Nadia, Millena Logrado, Jan Kergassner, Bingyu Zhang, Torsten
    Gutmann, and Gerd Buntkowsky. “Solid-State NMR of Heterogeneous Catalysts.” <i>ChemCatChem</i>,
    2024, e202401159. <a href="https://doi.org/10.1002/cctc.202401159">https://doi.org/10.1002/cctc.202401159</a>.
  ieee: 'N. Haro Mares, M. Logrado, J. Kergassner, B. Zhang, T. Gutmann, and G. Buntkowsky,
    “Solid-State NMR of Heterogeneous Catalysts,” <i>ChemCatChem</i>, p. e202401159,
    2024, doi: <a href="https://doi.org/10.1002/cctc.202401159">10.1002/cctc.202401159</a>.'
  mla: Haro Mares, Nadia, et al. “Solid-State NMR of Heterogeneous Catalysts.” <i>ChemCatChem</i>,
    John Wiley &#38; Sons, Ltd, 2024, p. e202401159, doi:<a href="https://doi.org/10.1002/cctc.202401159">10.1002/cctc.202401159</a>.
  short: N. Haro Mares, M. Logrado, J. Kergassner, B. Zhang, T. Gutmann, G. Buntkowsky,
    ChemCatChem (2024) e202401159.
date_created: 2026-02-07T15:40:38Z
date_updated: 2026-02-17T16:17:30Z
doi: 10.1002/cctc.202401159
extern: '1'
keyword:
- solid-state nmr
- heterogeneous catalysis
- dynamic nuclear polarization
- Nanocatalysis
- Surface-reactions
language:
- iso: eng
page: e202401159
publication: ChemCatChem
publication_identifier:
  issn:
  - 1867-3880
publisher: John Wiley & Sons, Ltd
status: public
title: Solid-State NMR of Heterogeneous Catalysts
type: journal_article
user_id: '100715'
year: '2024'
...
---
_id: '64052'
abstract:
- lang: eng
  text: Abstract Estuaries are key ecosystems with unique biodiversity and are of
    high economic importance. Along the estuaries, variations in environmental parameters,
    such as salinity and light penetration, can modify the characteristics of dissolved
    organic matter (DOM). Nevertheless, there is still limited information about the
    atomic-level transformations of DOM in this ecosystem. Solid-state NMR spectroscopy
    provides unique insights into the nature of functional groups in DOM. A major
    limitation of this technique is its lack of sensivity, which results in experimental
    time of tens of hours for the acquisition of 13C NMR spectra and generally precludes
    the observation of 15N nuclei for DOM. We show here how the sensitivity of solid-state
    NMR experiments on DOM of Seine estuary can be enhanced using dynamic nuclear
    polarization (DNP) under magic-angle spinning. This technique allows the acquisition
    of 13C NMR spectra of these samples in few minutes, instead of hours for conventional
    solid-state NMR. Both conventional and DNP-enhanced 13C NMR spectra indicate that
    the 13C local environments in DOM are not strongly modified along the Seine estuary.
    Furthermore, the sensitivity gain provided by the DNP allows the detection of
    15N NMR signal of DOM, in spite of the low nitrogen content. These spectra reveal
    that the majority of nitrogen is in the amide form in these DOM samples and show
    an increased disorder around these amide groups near the mouth of the Seine.
author:
- first_name: Florian
  full_name: Venel, Florian
  last_name: Venel
- first_name: Hiroki
  full_name: Nagashima, Hiroki
  last_name: Nagashima
- first_name: Andrew G. M.
  full_name: Rankin, Andrew G. M.
  last_name: Rankin
- first_name: Christelle
  full_name: Anquetil, Christelle
  last_name: Anquetil
- first_name: Vytautas
  full_name: Klimavicius, Vytautas
  last_name: Klimavicius
- first_name: Torsten
  full_name: Gutmann, Torsten
  id: '118165'
  last_name: Gutmann
- first_name: Gerd
  full_name: Buntkowsky, Gerd
  last_name: Buntkowsky
- first_name: Sylvie
  full_name: Derenne, Sylvie
  last_name: Derenne
- first_name: Olivier
  full_name: Lafon, Olivier
  last_name: Lafon
- first_name: Arnaud
  full_name: Huguet, Arnaud
  last_name: Huguet
- first_name: Frédérique
  full_name: Pourpoint, Frédérique
  last_name: Pourpoint
citation:
  ama: Venel F, Nagashima H, Rankin AGM, et al. Characterization of Functional Groups
    in Estuarine Dissolved Organic Matter by DNP-enhanced 15N and 13C Solid-State
    NMR. <i>Chemphyschem</i>. 2021;22(18):1907–1913. doi:<a href="https://doi.org/10.1002/cphc.202100334">10.1002/cphc.202100334</a>
  apa: Venel, F., Nagashima, H., Rankin, A. G. M., Anquetil, C., Klimavicius, V.,
    Gutmann, T., Buntkowsky, G., Derenne, S., Lafon, O., Huguet, A., &#38; Pourpoint,
    F. (2021). Characterization of Functional Groups in Estuarine Dissolved Organic
    Matter by DNP-enhanced 15N and 13C Solid-State NMR. <i>Chemphyschem</i>, <i>22</i>(18),
    1907–1913. <a href="https://doi.org/10.1002/cphc.202100334">https://doi.org/10.1002/cphc.202100334</a>
  bibtex: '@article{Venel_Nagashima_Rankin_Anquetil_Klimavicius_Gutmann_Buntkowsky_Derenne_Lafon_Huguet_et
    al._2021, title={Characterization of Functional Groups in Estuarine Dissolved
    Organic Matter by DNP-enhanced 15N and 13C Solid-State NMR}, volume={22}, DOI={<a
    href="https://doi.org/10.1002/cphc.202100334">10.1002/cphc.202100334</a>}, number={18},
    journal={Chemphyschem}, publisher={John Wiley &#38; Sons, Ltd}, author={Venel,
    Florian and Nagashima, Hiroki and Rankin, Andrew G. M. and Anquetil, Christelle
    and Klimavicius, Vytautas and Gutmann, Torsten and Buntkowsky, Gerd and Derenne,
    Sylvie and Lafon, Olivier and Huguet, Arnaud and et al.}, year={2021}, pages={1907–1913}
    }'
  chicago: 'Venel, Florian, Hiroki Nagashima, Andrew G. M. Rankin, Christelle Anquetil,
    Vytautas Klimavicius, Torsten Gutmann, Gerd Buntkowsky, et al. “Characterization
    of Functional Groups in Estuarine Dissolved Organic Matter by DNP-Enhanced 15N
    and 13C Solid-State NMR.” <i>Chemphyschem</i> 22, no. 18 (2021): 1907–1913. <a
    href="https://doi.org/10.1002/cphc.202100334">https://doi.org/10.1002/cphc.202100334</a>.'
  ieee: 'F. Venel <i>et al.</i>, “Characterization of Functional Groups in Estuarine
    Dissolved Organic Matter by DNP-enhanced 15N and 13C Solid-State NMR,” <i>Chemphyschem</i>,
    vol. 22, no. 18, pp. 1907–1913, 2021, doi: <a href="https://doi.org/10.1002/cphc.202100334">10.1002/cphc.202100334</a>.'
  mla: Venel, Florian, et al. “Characterization of Functional Groups in Estuarine
    Dissolved Organic Matter by DNP-Enhanced 15N and 13C Solid-State NMR.” <i>Chemphyschem</i>,
    vol. 22, no. 18, John Wiley &#38; Sons, Ltd, 2021, pp. 1907–1913, doi:<a href="https://doi.org/10.1002/cphc.202100334">10.1002/cphc.202100334</a>.
  short: F. Venel, H. Nagashima, A.G.M. Rankin, C. Anquetil, V. Klimavicius, T. Gutmann,
    G. Buntkowsky, S. Derenne, O. Lafon, A. Huguet, F. Pourpoint, Chemphyschem 22
    (2021) 1907–1913.
date_created: 2026-02-07T16:14:11Z
date_updated: 2026-02-17T16:12:56Z
doi: 10.1002/cphc.202100334
extern: '1'
intvolume: '        22'
issue: '18'
keyword:
- dynamic nuclear polarization
- 13C
- 15N
- dissolved organic matter
- Seine estuary
language:
- iso: eng
page: 1907–1913
publication: Chemphyschem
publication_identifier:
  issn:
  - 1439-4235; 1439-7641
publisher: John Wiley & Sons, Ltd
status: public
title: Characterization of Functional Groups in Estuarine Dissolved Organic Matter
  by DNP-enhanced 15N and 13C Solid-State NMR
type: journal_article
user_id: '100715'
volume: 22
year: '2021'
...
---
_id: '63969'
abstract:
- lang: eng
  text: A number of Ir-N-heterocyclic carbene (Ir-NHC) complexes with asymmetric N-heterocyclic
    carbene (NHC) ligands have been prepared and examined for signal amplification
    by reversible exchange (SABRE). Pyridine was chosen as model compound for hyperpolarization
    experiments. This substrate was examined in a solvent mixture using several Ir-NHC
    complexes, which differ in their NHC ligands. The SABRE polarization was created
    at 6mT and the H-1 nuclear magnetic resonancesignals were detected at 7T. We show
    that asymmetric NHC ligands, because of their favorable chemistry, can adapt the
    SABREactive complexes to different chemical scenarios.
author:
- first_name: S.
  full_name: Hadjiali, S.
  last_name: Hadjiali
- first_name: R.
  full_name: Savka, R.
  last_name: Savka
- first_name: M.
  full_name: Plaumann, M.
  last_name: Plaumann
- first_name: U.
  full_name: Bommerich, U.
  last_name: Bommerich
- first_name: S.
  full_name: Bothe, S.
  last_name: Bothe
- first_name: Torsten
  full_name: Gutmann, Torsten
  id: '118165'
  last_name: Gutmann
- first_name: T.
  full_name: Ratajczyk, T.
  last_name: Ratajczyk
- first_name: J.
  full_name: Bernarding, J.
  last_name: Bernarding
- first_name: H. H.
  full_name: Limbach, H. H.
  last_name: Limbach
- first_name: H.
  full_name: Plenio, H.
  last_name: Plenio
- first_name: G.
  full_name: Buntkowsky, G.
  last_name: Buntkowsky
citation:
  ama: Hadjiali S, Savka R, Plaumann M, et al. Substituent Influences on the NMR Signal
    Amplification of Ir Complexes with Heterocyclic Carbene Ligands. <i>Applied Magnetic
    Resonance</i>. 2019;50(7):895–902. doi:<a href="https://doi.org/10.1007/s00723-019-01115-x">10.1007/s00723-019-01115-x</a>
  apa: Hadjiali, S., Savka, R., Plaumann, M., Bommerich, U., Bothe, S., Gutmann, T.,
    Ratajczyk, T., Bernarding, J., Limbach, H. H., Plenio, H., &#38; Buntkowsky, G.
    (2019). Substituent Influences on the NMR Signal Amplification of Ir Complexes
    with Heterocyclic Carbene Ligands. <i>Applied Magnetic Resonance</i>, <i>50</i>(7),
    895–902. <a href="https://doi.org/10.1007/s00723-019-01115-x">https://doi.org/10.1007/s00723-019-01115-x</a>
  bibtex: '@article{Hadjiali_Savka_Plaumann_Bommerich_Bothe_Gutmann_Ratajczyk_Bernarding_Limbach_Plenio_et
    al._2019, title={Substituent Influences on the NMR Signal Amplification of Ir
    Complexes with Heterocyclic Carbene Ligands}, volume={50}, DOI={<a href="https://doi.org/10.1007/s00723-019-01115-x">10.1007/s00723-019-01115-x</a>},
    number={7}, journal={Applied Magnetic Resonance}, author={Hadjiali, S. and Savka,
    R. and Plaumann, M. and Bommerich, U. and Bothe, S. and Gutmann, Torsten and Ratajczyk,
    T. and Bernarding, J. and Limbach, H. H. and Plenio, H. and et al.}, year={2019},
    pages={895–902} }'
  chicago: 'Hadjiali, S., R. Savka, M. Plaumann, U. Bommerich, S. Bothe, Torsten Gutmann,
    T. Ratajczyk, et al. “Substituent Influences on the NMR Signal Amplification of
    Ir Complexes with Heterocyclic Carbene Ligands.” <i>Applied Magnetic Resonance</i>
    50, no. 7 (2019): 895–902. <a href="https://doi.org/10.1007/s00723-019-01115-x">https://doi.org/10.1007/s00723-019-01115-x</a>.'
  ieee: 'S. Hadjiali <i>et al.</i>, “Substituent Influences on the NMR Signal Amplification
    of Ir Complexes with Heterocyclic Carbene Ligands,” <i>Applied Magnetic Resonance</i>,
    vol. 50, no. 7, pp. 895–902, 2019, doi: <a href="https://doi.org/10.1007/s00723-019-01115-x">10.1007/s00723-019-01115-x</a>.'
  mla: Hadjiali, S., et al. “Substituent Influences on the NMR Signal Amplification
    of Ir Complexes with Heterocyclic Carbene Ligands.” <i>Applied Magnetic Resonance</i>,
    vol. 50, no. 7, 2019, pp. 895–902, doi:<a href="https://doi.org/10.1007/s00723-019-01115-x">10.1007/s00723-019-01115-x</a>.
  short: S. Hadjiali, R. Savka, M. Plaumann, U. Bommerich, S. Bothe, T. Gutmann, T.
    Ratajczyk, J. Bernarding, H.H. Limbach, H. Plenio, G. Buntkowsky, Applied Magnetic
    Resonance 50 (2019) 895–902.
date_created: 2026-02-07T15:40:18Z
date_updated: 2026-02-17T16:17:34Z
doi: 10.1007/s00723-019-01115-x
extern: '1'
intvolume: '        50'
issue: '7'
keyword:
- dynamic nuclear-polarization
- hyperpolarization
- enhancement
- hydrogen induced polarization
- olefin-metathesis catalysts
- parahydrogen-induced polarization
- peptides
- Physics
- sabre
- spectroscopy
language:
- iso: eng
page: 895–902
publication: Applied Magnetic Resonance
publication_identifier:
  issn:
  - 1613-7507
status: public
title: Substituent Influences on the NMR Signal Amplification of Ir Complexes with
  Heterocyclic Carbene Ligands
type: journal_article
user_id: '100715'
volume: 50
year: '2019'
...
---
_id: '63960'
abstract:
- lang: eng
  text: Recent advances in solid-state nuclear magnetic resonance (NMR) spectroscopy
    and dynamic nuclear polarization (DNP) of nanostructured materials are reviewed.
    A first group of materials is based on crystalline nanocellulose (CNC) or microcrystalline
    cellulose (MCC), which are used as carrier materials for dye molecules, catalysts
    or in combination with heterocyclic molecules as ion conducting membranes. These
    materials have widespread applications in sensorics, optics, catalysis or fuel
    cell research. A second group are metal oxides such as V-Mo-W oxides, which are
    of enormous importance in the manufacturing process of basic chemicals. The third
    group are catalytically active nanocrystalline metal nanoparticles, coated with
    protectants or embedded in polymers. The last group includes of lead-free perovskite
    materials, which are employed as environmentally benign substitution materials
    for conventional lead-based electronics materials. These materials are discussed
    in terms of their application and physico-chemical characterization by solid-state
    NMR techniques, combined with gas-phase NMR and quantum-chemical modelling on
    the density functional theory (DFT) level. The application of multinuclear 1H,
    2H, 13C, 15N and 23Na solid state NMR techniques under static or MAS conditions
    for the characterization of these materials, their surfaces and processes on their
    surfaces is discussed. Moreover, the analytic power of the combination of these
    techniques with DNP for the identification of low-concentrated carbon and nitrogen
    containing surface species in natural abundance is reviewed. Finally, approaches
    for sensitivity enhancement by DNP of quadrupolar nuclei such as 17O and 51V are
    presented that enable the identification of catalytic sites in metal oxide catalysts.
author:
- first_name: Torsten
  full_name: Gutmann, Torsten
  id: '118165'
  last_name: Gutmann
- first_name: Pedro B.
  full_name: Groszewicz, Pedro B.
  last_name: Groszewicz
- first_name: Gerd
  full_name: Buntkowsky, Gerd
  last_name: Buntkowsky
citation:
  ama: Gutmann T, Groszewicz PB, Buntkowsky G. Solid-state NMR of nanocrystals. <i>Annual
    Reports on NMR Spectroscopy</i>. 2019;97:1–82. doi:<a href="https://doi.org/10.1016/bs.arnmr.2018.12.001">10.1016/bs.arnmr.2018.12.001</a>
  apa: Gutmann, T., Groszewicz, P. B., &#38; Buntkowsky, G. (2019). Solid-state NMR
    of nanocrystals. <i>Annual Reports on NMR Spectroscopy</i>, <i>97</i>, 1–82. <a
    href="https://doi.org/10.1016/bs.arnmr.2018.12.001">https://doi.org/10.1016/bs.arnmr.2018.12.001</a>
  bibtex: '@article{Gutmann_Groszewicz_Buntkowsky_2019, title={Solid-state NMR of
    nanocrystals}, volume={97}, DOI={<a href="https://doi.org/10.1016/bs.arnmr.2018.12.001">10.1016/bs.arnmr.2018.12.001</a>},
    journal={Annual Reports on NMR Spectroscopy}, author={Gutmann, Torsten and Groszewicz,
    Pedro B. and Buntkowsky, Gerd}, year={2019}, pages={1–82} }'
  chicago: 'Gutmann, Torsten, Pedro B. Groszewicz, and Gerd Buntkowsky. “Solid-State
    NMR of Nanocrystals.” <i>Annual Reports on NMR Spectroscopy</i> 97 (2019): 1–82.
    <a href="https://doi.org/10.1016/bs.arnmr.2018.12.001">https://doi.org/10.1016/bs.arnmr.2018.12.001</a>.'
  ieee: 'T. Gutmann, P. B. Groszewicz, and G. Buntkowsky, “Solid-state NMR of nanocrystals,”
    <i>Annual Reports on NMR Spectroscopy</i>, vol. 97, pp. 1–82, 2019, doi: <a href="https://doi.org/10.1016/bs.arnmr.2018.12.001">10.1016/bs.arnmr.2018.12.001</a>.'
  mla: Gutmann, Torsten, et al. “Solid-State NMR of Nanocrystals.” <i>Annual Reports
    on NMR Spectroscopy</i>, vol. 97, 2019, pp. 1–82, doi:<a href="https://doi.org/10.1016/bs.arnmr.2018.12.001">10.1016/bs.arnmr.2018.12.001</a>.
  short: T. Gutmann, P.B. Groszewicz, G. Buntkowsky, Annual Reports on NMR Spectroscopy
    97 (2019) 1–82.
date_created: 2026-02-07T15:37:03Z
date_updated: 2026-02-17T16:17:56Z
doi: 10.1016/bs.arnmr.2018.12.001
extern: '1'
intvolume: '        97'
keyword:
- solid-state nmr
- heterogeneous catalysis
- dynamic nuclear polarization
- Ferroelectrics
- Nanocatalysis
- Surface reactions
language:
- iso: eng
page: 1–82
publication: Annual Reports on NMR Spectroscopy
status: public
title: Solid-state NMR of nanocrystals
type: journal_article
user_id: '100715'
volume: 97
year: '2019'
...
---
_id: '63956'
abstract:
- lang: eng
  text: The synthesis of novel robust and stable iridium-based immobilized catalysts
    on silica-polymer hybrid materials (Si-PB-Ir) is described. These catalysts are
    characterized by a combination of 1D P-31 CP-MAS and 2D P-31-H-1 HETCOR and J-resolved
    multinuclear solid state NMR experiments. Different binding situations such as
    singly and multiply coordinated phosphines are identified. Density functional
    theory (DFT) calculations are performed to corroborate the interpretation of the
    experimental NMR data, in order to propose a structural model of the heterogenized
    catalysts. Finally, the catalytic activity of the Si-PB-Ir catalysts is investigated
    for the hydrogenation of styrene employing para-enriched hydrogen gas.
author:
- first_name: Torsten
  full_name: Gutmann, Torsten
  id: '118165'
  last_name: Gutmann
- first_name: S.
  full_name: Alkhagani, S.
  last_name: Alkhagani
- first_name: N.
  full_name: Rothermel, N.
  last_name: Rothermel
- first_name: H. H.
  full_name: Limbach, H. H.
  last_name: Limbach
- first_name: H.
  full_name: Breitzke, H.
  last_name: Breitzke
- first_name: G.
  full_name: Buntkowsky, G.
  last_name: Buntkowsky
citation:
  ama: Gutmann T, Alkhagani S, Rothermel N, Limbach HH, Breitzke H, Buntkowsky G.
    P-31-Solid-State NMR Characterization and Catalytic Hydrogenation Tests of Novel
    heterogenized Iridium-Catalysts. <i>Zeitschrift Fur Physikalische Chemie-International
    Journal of Research in Physical Chemistry &#38; Chemical Physics</i>. 2017;231(3):653–669.
    doi:<a href="https://doi.org/10.1515/zpch-2016-0837">10.1515/zpch-2016-0837</a>
  apa: Gutmann, T., Alkhagani, S., Rothermel, N., Limbach, H. H., Breitzke, H., &#38;
    Buntkowsky, G. (2017). P-31-Solid-State NMR Characterization and Catalytic Hydrogenation
    Tests of Novel heterogenized Iridium-Catalysts. <i>Zeitschrift Fur Physikalische
    Chemie-International Journal of Research in Physical Chemistry &#38; Chemical
    Physics</i>, <i>231</i>(3), 653–669. <a href="https://doi.org/10.1515/zpch-2016-0837">https://doi.org/10.1515/zpch-2016-0837</a>
  bibtex: '@article{Gutmann_Alkhagani_Rothermel_Limbach_Breitzke_Buntkowsky_2017,
    title={P-31-Solid-State NMR Characterization and Catalytic Hydrogenation Tests
    of Novel heterogenized Iridium-Catalysts}, volume={231}, DOI={<a href="https://doi.org/10.1515/zpch-2016-0837">10.1515/zpch-2016-0837</a>},
    number={3}, journal={Zeitschrift Fur Physikalische Chemie-International Journal
    of Research in Physical Chemistry &#38; Chemical Physics}, author={Gutmann, Torsten
    and Alkhagani, S. and Rothermel, N. and Limbach, H. H. and Breitzke, H. and Buntkowsky,
    G.}, year={2017}, pages={653–669} }'
  chicago: 'Gutmann, Torsten, S. Alkhagani, N. Rothermel, H. H. Limbach, H. Breitzke,
    and G. Buntkowsky. “P-31-Solid-State NMR Characterization and Catalytic Hydrogenation
    Tests of Novel Heterogenized Iridium-Catalysts.” <i>Zeitschrift Fur Physikalische
    Chemie-International Journal of Research in Physical Chemistry &#38; Chemical
    Physics</i> 231, no. 3 (2017): 653–669. <a href="https://doi.org/10.1515/zpch-2016-0837">https://doi.org/10.1515/zpch-2016-0837</a>.'
  ieee: 'T. Gutmann, S. Alkhagani, N. Rothermel, H. H. Limbach, H. Breitzke, and G.
    Buntkowsky, “P-31-Solid-State NMR Characterization and Catalytic Hydrogenation
    Tests of Novel heterogenized Iridium-Catalysts,” <i>Zeitschrift Fur Physikalische
    Chemie-International Journal of Research in Physical Chemistry &#38; Chemical
    Physics</i>, vol. 231, no. 3, pp. 653–669, 2017, doi: <a href="https://doi.org/10.1515/zpch-2016-0837">10.1515/zpch-2016-0837</a>.'
  mla: Gutmann, Torsten, et al. “P-31-Solid-State NMR Characterization and Catalytic
    Hydrogenation Tests of Novel Heterogenized Iridium-Catalysts.” <i>Zeitschrift
    Fur Physikalische Chemie-International Journal of Research in Physical Chemistry
    &#38; Chemical Physics</i>, vol. 231, no. 3, 2017, pp. 653–669, doi:<a href="https://doi.org/10.1515/zpch-2016-0837">10.1515/zpch-2016-0837</a>.
  short: T. Gutmann, S. Alkhagani, N. Rothermel, H.H. Limbach, H. Breitzke, G. Buntkowsky,
    Zeitschrift Fur Physikalische Chemie-International Journal of Research in Physical
    Chemistry &#38; Chemical Physics 231 (2017) 653–669.
date_created: 2026-02-07T15:35:41Z
date_updated: 2026-02-17T16:18:04Z
doi: 10.1515/zpch-2016-0837
extern: '1'
intvolume: '       231'
issue: '3'
keyword:
- Chemistry
- dynamic nuclear-polarization
- solid-state nmr
- DFT
- heterogeneous catalysis
- hydrido complexes
- hydrogenation
- immobilized catalyst
- inorganic hybrid
- iridium
- materials
- mesoporous
- molecular-orbital methods
- PHIP
- phosphine complexes
- reusable catalysts
- silica
- solid-state-NMR
- wilkinsons catalyst
language:
- iso: eng
page: 653–669
publication: Zeitschrift Fur Physikalische Chemie-International Journal of Research
  in Physical Chemistry & Chemical Physics
publication_identifier:
  issn:
  - 0942-9352
status: public
title: P-31-Solid-State NMR Characterization and Catalytic Hydrogenation Tests of
  Novel heterogenized Iridium-Catalysts
type: journal_article
user_id: '100715'
volume: 231
year: '2017'
...
---
_id: '63920'
abstract:
- lang: eng
  text: Coordinatively unsaturated sites (CUS) present a key feature of alumina based
    catalysts as they are believed to act as Lewis-acid sites in heterogeneously catalyzed
    reactions. In the present study, the direct observation of active species on a
    fluoride-doped aluminum oxide catalyst is demonstrated. This new fluoride-doped
    aluminum oxide exhibits strong Lewis-acid sites and superior catalytic activity
    as compared to gamma-Al2O3. To emphasize the labile state of Lewis-acid sites,
    two distinctive states of the catalysts surface are addressed using H-1-Al-27
    cross polarization (CP) MAS NMR. On the one hand, the highly dehydrated and active
    state after calcination at 700 degrees C and on the other hand the rehydrated
    and catalytically inactive surface (produced by contact to air) are probed. These
    experiments revealed the presence of significant amounts of coordinatively unsaturated
    sites in the form of 4-and 5-fold coordinated Al-sites on the highly dehydrated
    surface. In contrast to this, the rehydrated sample exhibited a severely restructured
    surface caused by the chemisorption of H2O which is ’constituted in a manner that
    was proposed in earlier models for gamma-Al2O3 surfaces.
author:
- first_name: L.
  full_name: Ahrem, L.
  last_name: Ahrem
- first_name: G.
  full_name: Scholz, G.
  last_name: Scholz
- first_name: Torsten
  full_name: Gutmann, Torsten
  id: '118165'
  last_name: Gutmann
- first_name: B.
  full_name: Calvo, B.
  last_name: Calvo
- first_name: G.
  full_name: Buntkowsky, G.
  last_name: Buntkowsky
- first_name: E.
  full_name: Kemnitz, E.
  last_name: Kemnitz
citation:
  ama: Ahrem L, Scholz G, Gutmann T, Calvo B, Buntkowsky G, Kemnitz E. Direct Observation
    of Coordinatively Unsaturated Sites on the Surface of a Fluoride-Doped Alumina
    Catalyst. <i>Journal of Physical Chemistry C</i>. 2017;121(22):12206–12213. doi:<a
    href="https://doi.org/10.1021/acs.jpcc.7b02535">10.1021/acs.jpcc.7b02535</a>
  apa: Ahrem, L., Scholz, G., Gutmann, T., Calvo, B., Buntkowsky, G., &#38; Kemnitz,
    E. (2017). Direct Observation of Coordinatively Unsaturated Sites on the Surface
    of a Fluoride-Doped Alumina Catalyst. <i>Journal of Physical Chemistry C</i>,
    <i>121</i>(22), 12206–12213. <a href="https://doi.org/10.1021/acs.jpcc.7b02535">https://doi.org/10.1021/acs.jpcc.7b02535</a>
  bibtex: '@article{Ahrem_Scholz_Gutmann_Calvo_Buntkowsky_Kemnitz_2017, title={Direct
    Observation of Coordinatively Unsaturated Sites on the Surface of a Fluoride-Doped
    Alumina Catalyst}, volume={121}, DOI={<a href="https://doi.org/10.1021/acs.jpcc.7b02535">10.1021/acs.jpcc.7b02535</a>},
    number={22}, journal={Journal of Physical Chemistry C}, author={Ahrem, L. and
    Scholz, G. and Gutmann, Torsten and Calvo, B. and Buntkowsky, G. and Kemnitz,
    E.}, year={2017}, pages={12206–12213} }'
  chicago: 'Ahrem, L., G. Scholz, Torsten Gutmann, B. Calvo, G. Buntkowsky, and E.
    Kemnitz. “Direct Observation of Coordinatively Unsaturated Sites on the Surface
    of a Fluoride-Doped Alumina Catalyst.” <i>Journal of Physical Chemistry C</i>
    121, no. 22 (2017): 12206–12213. <a href="https://doi.org/10.1021/acs.jpcc.7b02535">https://doi.org/10.1021/acs.jpcc.7b02535</a>.'
  ieee: 'L. Ahrem, G. Scholz, T. Gutmann, B. Calvo, G. Buntkowsky, and E. Kemnitz,
    “Direct Observation of Coordinatively Unsaturated Sites on the Surface of a Fluoride-Doped
    Alumina Catalyst,” <i>Journal of Physical Chemistry C</i>, vol. 121, no. 22, pp.
    12206–12213, 2017, doi: <a href="https://doi.org/10.1021/acs.jpcc.7b02535">10.1021/acs.jpcc.7b02535</a>.'
  mla: Ahrem, L., et al. “Direct Observation of Coordinatively Unsaturated Sites on
    the Surface of a Fluoride-Doped Alumina Catalyst.” <i>Journal of Physical Chemistry
    C</i>, vol. 121, no. 22, 2017, pp. 12206–12213, doi:<a href="https://doi.org/10.1021/acs.jpcc.7b02535">10.1021/acs.jpcc.7b02535</a>.
  short: L. Ahrem, G. Scholz, T. Gutmann, B. Calvo, G. Buntkowsky, E. Kemnitz, Journal
    of Physical Chemistry C 121 (2017) 12206–12213.
date_created: 2026-02-07T08:56:18Z
date_updated: 2026-02-17T16:19:24Z
doi: 10.1021/acs.jpcc.7b02535
extern: '1'
intvolume: '       121'
issue: '22'
keyword:
- al-27 nmr
- characterization
- Chemistry
- cross-polarization
- dynamic nuclear-polarization
- eta-alumina
- gamma-alumina
- hydroxy fluorides
- ions
- Materials Science
- pentacoordinated al3+
- Science & Technology - Other Topics
- solid-state nmr
- spectroscopic
- structural insights
language:
- iso: eng
page: 12206–12213
publication: Journal of Physical Chemistry C
publication_identifier:
  issn:
  - 1932-7447
status: public
title: Direct Observation of Coordinatively Unsaturated Sites on the Surface of a
  Fluoride-Doped Alumina Catalyst
type: journal_article
user_id: '100715'
volume: 121
year: '2017'
...
---
_id: '4246'
abstract:
- lang: eng
  text: Spins in semiconductor quantum dots have been considered as prospective quantum
    bit excitations. Their coupling to the crystal environment manifests itself in
    a limitation of the spin coherence times to the microsecond range, both for electron
    and hole spins. This rather short-lived coherence compared to atomic states asks
    for manipulations on timescales as short as possible. Due to the huge dipole moment
    for transitions between the valence and conduction band, pulsed laser systems
    offer the possibility to perform manipulations within picoseconds or even faster.
    Here, we report on results that show the potential of optical spin manipulations
    with currently available pulsed laser systems. Using picosecond laser pulses,
    we demonstrate optically induced spin rotations of electron and hole spins. We
    further realize the optical decoupling of the hole spins from the nuclear surrounding
    at the nanosecond timescales and demonstrate an all-optical spin tomography for
    interacting electron spin sub-ensembles.
article_number: '17'
article_type: original
author:
- first_name: S.
  full_name: Varwig, S.
  last_name: Varwig
- first_name: E.
  full_name: Evers, E.
  last_name: Evers
- first_name: A.
  full_name: Greilich, A.
  last_name: Greilich
- first_name: D. R.
  full_name: Yakovlev, D. R.
  last_name: Yakovlev
- first_name: Dirk
  full_name: Reuter, Dirk
  id: '37763'
  last_name: Reuter
- first_name: A. D.
  full_name: Wieck, A. D.
  last_name: Wieck
- first_name: Torsten
  full_name: Meier, Torsten
  id: '344'
  last_name: Meier
  orcid: 0000-0001-8864-2072
- first_name: Artur
  full_name: Zrenner, Artur
  id: '606'
  last_name: Zrenner
  orcid: 0000-0002-5190-0944
- first_name: M.
  full_name: Bayer, M.
  last_name: Bayer
citation:
  ama: Varwig S, Evers E, Greilich A, et al. Advanced optical manipulation of carrier
    spins in (In,Ga)As quantum dots. <i>Applied Physics B</i>. 2016;122(1). doi:<a
    href="https://doi.org/10.1007/s00340-015-6274-y">10.1007/s00340-015-6274-y</a>
  apa: Varwig, S., Evers, E., Greilich, A., Yakovlev, D. R., Reuter, D., Wieck, A.
    D., Meier, T., Zrenner, A., &#38; Bayer, M. (2016). Advanced optical manipulation
    of carrier spins in (In,Ga)As quantum dots. <i>Applied Physics B</i>, <i>122</i>(1),
    Article 17. <a href="https://doi.org/10.1007/s00340-015-6274-y">https://doi.org/10.1007/s00340-015-6274-y</a>
  bibtex: '@article{Varwig_Evers_Greilich_Yakovlev_Reuter_Wieck_Meier_Zrenner_Bayer_2016,
    title={Advanced optical manipulation of carrier spins in (In,Ga)As quantum dots},
    volume={122}, DOI={<a href="https://doi.org/10.1007/s00340-015-6274-y">10.1007/s00340-015-6274-y</a>},
    number={117}, journal={Applied Physics B}, publisher={Springer Nature}, author={Varwig,
    S. and Evers, E. and Greilich, A. and Yakovlev, D. R. and Reuter, Dirk and Wieck,
    A. D. and Meier, Torsten and Zrenner, Artur and Bayer, M.}, year={2016} }'
  chicago: Varwig, S., E. Evers, A. Greilich, D. R. Yakovlev, Dirk Reuter, A. D. Wieck,
    Torsten Meier, Artur Zrenner, and M. Bayer. “Advanced Optical Manipulation of
    Carrier Spins in (In,Ga)As Quantum Dots.” <i>Applied Physics B</i> 122, no. 1
    (2016). <a href="https://doi.org/10.1007/s00340-015-6274-y">https://doi.org/10.1007/s00340-015-6274-y</a>.
  ieee: 'S. Varwig <i>et al.</i>, “Advanced optical manipulation of carrier spins
    in (In,Ga)As quantum dots,” <i>Applied Physics B</i>, vol. 122, no. 1, Art. no.
    17, 2016, doi: <a href="https://doi.org/10.1007/s00340-015-6274-y">10.1007/s00340-015-6274-y</a>.'
  mla: Varwig, S., et al. “Advanced Optical Manipulation of Carrier Spins in (In,Ga)As
    Quantum Dots.” <i>Applied Physics B</i>, vol. 122, no. 1, 17, Springer Nature,
    2016, doi:<a href="https://doi.org/10.1007/s00340-015-6274-y">10.1007/s00340-015-6274-y</a>.
  short: S. Varwig, E. Evers, A. Greilich, D.R. Yakovlev, D. Reuter, A.D. Wieck, T.
    Meier, A. Zrenner, M. Bayer, Applied Physics B 122 (2016).
date_created: 2018-08-29T08:35:10Z
date_updated: 2025-12-16T16:44:01Z
department:
- _id: '15'
- _id: '230'
- _id: '35'
- _id: '170'
- _id: '293'
- _id: '292'
- _id: '35'
- _id: '290'
doi: 10.1007/s00340-015-6274-y
intvolume: '       122'
issue: '1'
keyword:
- Spin Polarization
- Pump Pulse
- Trion
- Spin Component
- Coherence Time
language:
- iso: eng
publication: Applied Physics B
publication_identifier:
  issn:
  - 0946-2171
  - 1432-0649
publication_status: published
publisher: Springer Nature
status: public
title: Advanced optical manipulation of carrier spins in (In,Ga)As quantum dots
type: journal_article
user_id: '16199'
volume: 122
year: '2016'
...
---
_id: '63963'
abstract:
- lang: eng
  text: A novel heterogeneous dirhodium catalyst has been synthesized. This stable
    catalyst is constructed from dirhodium acetate dimer (Rh2(OAc)4) units, which
    are covalently linked to amine- and carboxyl-bifunctionalized mesoporous silica
    (SBA-15NH2COOH). It shows good efficiency in catalyzing the cyclopropanation
    reaction of styrene and ethyl diazoacetate (EDA) forming cis- and trans-1-ethoxycarbonyl-2-phenylcyclopropane.
    To characterize the structure of this catalyst and to confirm the successful immobilization,
    heteronuclear solid-state NMR experiments have been performed. The high application
    potential of dynamic nuclear polarization (DNP) NMR for the analysis of binding
    sites in this novel catalyst is demonstrated. Signal-enhanced 13C CP MAS and 15N
    CP MAS techniques have been employed to detect different carboxyl and amine binding
    sites in natural abundance on a fast time scale. The interpretation of the experimental
    chemical shift values for different binding sites has been corroborated by quantum
    chemical calculations on dirhodium model complexes.
author:
- first_name: Torsten
  full_name: Gutmann, Torsten
  id: '118165'
  last_name: Gutmann
- first_name: Jiquan
  full_name: Liu, Jiquan
  last_name: Liu
- first_name: Niels
  full_name: Rothermel, Niels
  last_name: Rothermel
- first_name: Yeping
  full_name: Xu, Yeping
  last_name: Xu
- first_name: Eva
  full_name: Jaumann, Eva
  last_name: Jaumann
- first_name: Mayke
  full_name: Werner, Mayke
  last_name: Werner
- first_name: Hergen
  full_name: Breitzke, Hergen
  last_name: Breitzke
- first_name: Snorri T.
  full_name: Sigurdsson, Snorri T.
  last_name: Sigurdsson
- first_name: Gerd
  full_name: Buntkowsky, Gerd
  last_name: Buntkowsky
citation:
  ama: 'Gutmann T, Liu J, Rothermel N, et al. Natural Abundance 15N NMR by Dynamic
    Nuclear Polarization: Fast Analysis of Binding Sites of a Novel Amine-Carboxyl-Linked
    Immobilized Dirhodium Catalyst. <i>Chemistry A European Journal</i>. 2015;21(9):3798–3805.
    doi:<a href="https://doi.org/10.1002/chem.201405043">10.1002/chem.201405043</a>'
  apa: 'Gutmann, T., Liu, J., Rothermel, N., Xu, Y., Jaumann, E., Werner, M., Breitzke,
    H., Sigurdsson, S. T., &#38; Buntkowsky, G. (2015). Natural Abundance 15N NMR
    by Dynamic Nuclear Polarization: Fast Analysis of Binding Sites of a Novel Amine-Carboxyl-Linked
    Immobilized Dirhodium Catalyst. <i>Chemistry A European Journal</i>, <i>21</i>(9),
    3798–3805. <a href="https://doi.org/10.1002/chem.201405043">https://doi.org/10.1002/chem.201405043</a>'
  bibtex: '@article{Gutmann_Liu_Rothermel_Xu_Jaumann_Werner_Breitzke_Sigurdsson_Buntkowsky_2015,
    title={Natural Abundance 15N NMR by Dynamic Nuclear Polarization: Fast Analysis
    of Binding Sites of a Novel Amine-Carboxyl-Linked Immobilized Dirhodium Catalyst},
    volume={21}, DOI={<a href="https://doi.org/10.1002/chem.201405043">10.1002/chem.201405043</a>},
    number={9}, journal={Chemistry A European Journal}, publisher={WILEY-VCH Verlag},
    author={Gutmann, Torsten and Liu, Jiquan and Rothermel, Niels and Xu, Yeping and
    Jaumann, Eva and Werner, Mayke and Breitzke, Hergen and Sigurdsson, Snorri T.
    and Buntkowsky, Gerd}, year={2015}, pages={3798–3805} }'
  chicago: 'Gutmann, Torsten, Jiquan Liu, Niels Rothermel, Yeping Xu, Eva Jaumann,
    Mayke Werner, Hergen Breitzke, Snorri T. Sigurdsson, and Gerd Buntkowsky. “Natural
    Abundance 15N NMR by Dynamic Nuclear Polarization: Fast Analysis of Binding Sites
    of a Novel Amine-Carboxyl-Linked Immobilized Dirhodium Catalyst.” <i>Chemistry
    A European Journal</i> 21, no. 9 (2015): 3798–3805. <a href="https://doi.org/10.1002/chem.201405043">https://doi.org/10.1002/chem.201405043</a>.'
  ieee: 'T. Gutmann <i>et al.</i>, “Natural Abundance 15N NMR by Dynamic Nuclear Polarization:
    Fast Analysis of Binding Sites of a Novel Amine-Carboxyl-Linked Immobilized Dirhodium
    Catalyst,” <i>Chemistry A European Journal</i>, vol. 21, no. 9, pp. 3798–3805,
    2015, doi: <a href="https://doi.org/10.1002/chem.201405043">10.1002/chem.201405043</a>.'
  mla: 'Gutmann, Torsten, et al. “Natural Abundance 15N NMR by Dynamic Nuclear Polarization:
    Fast Analysis of Binding Sites of a Novel Amine-Carboxyl-Linked Immobilized Dirhodium
    Catalyst.” <i>Chemistry A European Journal</i>, vol. 21, no. 9, WILEY-VCH Verlag,
    2015, pp. 3798–3805, doi:<a href="https://doi.org/10.1002/chem.201405043">10.1002/chem.201405043</a>.'
  short: T. Gutmann, J. Liu, N. Rothermel, Y. Xu, E. Jaumann, M. Werner, H. Breitzke,
    S.T. Sigurdsson, G. Buntkowsky, Chemistry A European Journal 21 (2015) 3798–3805.
date_created: 2026-02-07T15:38:07Z
date_updated: 2026-02-17T16:17:50Z
doi: 10.1002/chem.201405043
extern: '1'
intvolume: '        21'
issue: '9'
keyword:
- heterogeneous catalysis
- immobilized catalyst
- dynamic nuclear polarization
- hyperpolarization
- NMR spectroscopy
language:
- iso: eng
page: 3798–3805
publication: Chemistry A European Journal
publisher: WILEY-VCH Verlag
status: public
title: 'Natural Abundance 15N NMR by Dynamic Nuclear Polarization: Fast Analysis of
  Binding Sites of a Novel Amine-Carboxyl-Linked Immobilized Dirhodium Catalyst'
type: journal_article
user_id: '100715'
volume: 21
year: '2015'
...
---
_id: '13326'
abstract:
- lang: eng
  text: Communication within online social network applications enables users to express
    and share sentiments electronically. Existing studies examined the existence or
    distribution of sentiments in online communication at a general level or in small-observed
    groups. Our paper extends this research by analyzing sentiment exchange within
    social networks from an ego-network perspective. We draw from research on social
    influence and social attachment to develop theories of node polarization, balance
    effects and sentiment mirroring within communication dyads. Our empirical analysis
    covers a multitude of social networks in which the sentiment valence of all messages
    was determined. Subsequently we studied ego-networks of focal actors (ego) and
    their immediate contacts. Results support our theories and indicate that actors
    develop polarized sentiments towards individual peers but keep sentiment in balance
    on the ego-network level. Further, pairs of nodes tend to establish similar attitudes
    towards each other leading to stable and polarized positive or negative relationships
author:
- first_name: Robert
  full_name: Hillmann, Robert
  last_name: Hillmann
- first_name: Matthias
  full_name: Trier, Matthias
  id: '72744'
  last_name: Trier
citation:
  ama: 'Hillmann R, Trier M. Sentiment Polarization and Balance among Users in Online
    Social Networks. In: Joshi KD, Yoo Y, eds. <i>AMCIS 2012 Proceedings</i>. Vol
    24. Association for Information Systems. AIS Electronic Library (AISeL); 2012.'
  apa: Hillmann, R., &#38; Trier, M. (2012). Sentiment Polarization and Balance among
    Users in Online Social Networks. In K. D. Joshi &#38; Y. Yoo (Eds.), <i>AMCIS
    2012 Proceedings</i> (Vol. 24). Association for Information Systems. AIS Electronic
    Library (AISeL).
  bibtex: '@inproceedings{Hillmann_Trier_2012, title={Sentiment Polarization and Balance
    among Users in Online Social Networks}, volume={24}, booktitle={AMCIS 2012 Proceedings},
    publisher={Association for Information Systems. AIS Electronic Library (AISeL)},
    author={Hillmann, Robert and Trier, Matthias}, editor={Joshi, K.D. and Yoo, YoungjinEditors},
    year={2012} }'
  chicago: Hillmann, Robert, and Matthias Trier. “Sentiment Polarization and Balance
    among Users in Online Social Networks.” In <i>AMCIS 2012 Proceedings</i>, edited
    by K.D. Joshi and Youngjin Yoo, Vol. 24. Association for Information Systems.
    AIS Electronic Library (AISeL), 2012.
  ieee: R. Hillmann and M. Trier, “Sentiment Polarization and Balance among Users
    in Online Social Networks,” in <i>AMCIS 2012 Proceedings</i>, 2012, vol. 24.
  mla: Hillmann, Robert, and Matthias Trier. “Sentiment Polarization and Balance among
    Users in Online Social Networks.” <i>AMCIS 2012 Proceedings</i>, edited by K.D.
    Joshi and Youngjin Yoo, vol. 24, Association for Information Systems. AIS Electronic
    Library (AISeL), 2012.
  short: 'R. Hillmann, M. Trier, in: K.D. Joshi, Y. Yoo (Eds.), AMCIS 2012 Proceedings,
    Association for Information Systems. AIS Electronic Library (AISeL), 2012.'
date_created: 2019-09-19T12:22:08Z
date_updated: 2022-01-06T06:51:33Z
department:
- _id: '198'
editor:
- first_name: K.D.
  full_name: Joshi, K.D.
  last_name: Joshi
- first_name: Youngjin
  full_name: Yoo, Youngjin
  last_name: Yoo
intvolume: '        24'
keyword:
- Social Network Analysis
- Ego-Network Analysis
- Node Polarization
- Sentiment Dissemination
language:
- iso: eng
publication: AMCIS 2012 Proceedings
publisher: Association for Information Systems. AIS Electronic Library (AISeL)
status: public
title: Sentiment Polarization and Balance among Users in Online Social Networks
type: conference
user_id: '62809'
volume: 24
year: '2012'
...