0000000000754717
AUTHOR
Tobias Unruh
showing 4 related works from this author
Inelastic neutron and low-frequency Raman scattering in niobium-phosphate glasses: the role of spatially fluctuating elastic and elasto-optic constan…
2011
We investigate the low-frequency enhancement of vibrational excitations ('boson peak') in niobium-phosphate glasses through the combination of inelastic neutron and polarization-resolved Raman scattering. The spectra of these glasses reveal an enhancement of the vibrational density of states and of the cross section for spontaneous Raman scattering in the frequency range below 150?cm ? 1. A recent theoretical model that is based on fluctuating elastic and elasto-optic (Pockels) constants provides a unified description of the measured neutron and Raman spectra, including the depolarization ratio.
Interface Molecular engineering for laminated monolithic perovskite/silicon tandem solar cells with 80.4% fill factor
2019
The Cluster of Excellence funded this work through “Engineering of Advanced Materials” (EAM). The authors acknowledge financial support from the DFG research-training group GRK 1896 at Erlangen University and from the Joint Project Helmholtz-Institute Erlangen Nurnberg (HI-ERN) under Project No. DBF01253, respectively. C.J.B. acknowledges the financial support through the “Aufbruch Bayern” initiative of the state of Bavaria (EnCN and Solar Factory of the Future) and the “Solar Factory of the Future” with the Energy Campus Nurnberg (EnCN). S.L. acknowledges the Real Colegio Complutense in Harvard for a research grant, and to the Spanish Ministerio de Ciencia e Innovacion for a fellowship thr…
Reduced grey brookite for noble metal free photocatalytic H2evolution
2021
Herein we introduce for the first time a reduced “grey” brookite TiO2 photocatalyst, produced by thermal hydrogenation of brookite nanoparticles, that shows a remarkable noble metal free photocatalytic H2 evolution. Its activity is substantially higher than that of other TiO2 polymorphs, i.e. anatase or rutile, comparably sized and activated by hydrogenation under optimized conditions. Along with brookite powders, an oriented brookite single crystal was investigated as a defined surface to confirm the effects of the hydrogenation treatment. By a combination of electron paramagnetic resonance (EPR), electron and X-ray characterization techniques applied to the powders and single crystal, we …
Inelastic neutron and low-frequency Raman scattering in a niobium-phosphate glass for Raman gain applications
2011
Abstract We present measurements of the vibrational spectrum of a binary niobium-phosphate glass in the THz frequency range using inelastic neutron and Raman scattering. The spectra of these glasses show a low-frequency enhancement of the vibrational density of states (“boson peak”). Using a recently developed theory of vibrational excitations in disordered solids we are able to reconcile the measured neutron and Raman spectra using fluctuating elastic and Pockels constants as a model concept. As the spontaneous Raman susceptibility is a key parameter for Raman amplification our results suggest a significant gain profile for application of niobium-phosphate glasses in Raman amplifiers.