The Polaron Pair (PP) model has been successfully applied to magnetoconductance (MC) in organic semiconductor devices under ultra-small magnetic fields (USMFE). We report µT resolution MC measurements carried out with high sensitivity (better than 10) on the common organic semiconductor tris-(8-hydroxyquinoline)aluminium in the range ±500 µT displaying clear minima at ~±240 µT. Unlike traditional approaches, where device MC is simply evaluated using the PP model using nominal parameters for microscopic quantities such as the local hyperfine magnetic field, we have carried out actual fitting of the PP MC model to the experimentally obtained data. The fitting procedure yields physically realistic values for the polaron pair decay rate, local hyperfine magnetic field and triplet contribution to dissociation namely: [Formula: see text] = 28.6 ± 9.7 MHz, [Formula: see text] = 0.34 ± 0.04 mT and [Formula: see text] = 0.99 ± 0.01 respectively. The local hyperfine field obtained by fitting is in excellent agreement with independently calculated values for this system and is reproducible across different devices and independent of drive conditions. This demonstrates the applicability of the fitting approach to any organic USMFE MC data for obtaining microscopic parameter values.
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http://dx.doi.org/10.1038/s41598-019-40132-5 | DOI Listing |
J Phys Chem A
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University of Göttingen, Institute for Physical Chemistry, Tammannstraße 6, 37077,Göttingen Germany.
Rotational spectroscopy is an excellent tool for structure determination, which can provide additional insights into local electronic structure by investigating the hyperfine pattern due to nuclear quadrupole coupling. Jet-cooled molecules are good experimental benchmark targets for electronic structure calculations, as they are free of environmental effects. We report the rotational spectra of 2-chlorobenzaldehyde, 3-chlorobenzaldehyde, and 4-chlorobenzaldehyde, including a complete experimental description of the nuclear quadrupole coupling constants, which were previously not experimentally determined.
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January 2025
Otto Schott Institute of Materials Research, Friedrich Schiller University Jena, Löbdergraben 32, 07743 Jena, Germany.
Density functional theory has become the workhorse of quantum physics, chemistry, and materials science. Within these fields, a broad range of applications needs to be covered. These applications range from solids to molecular systems, from organic to inorganic chemistry, or even from electrons to other Fermions, such as protons or muons.
View Article and Find Full Text PDFPhys Chem Chem Phys
December 2024
Department of Chemistry, Redeemer University, Ancaster, ON, Canada.
A modified shifted-echo PIETA pulse sequence is developed to acquire natural abundance Si 2D -resolved spectra in crystalline silicates. The sequence is applied to the highly siliceous zeolites Sigma-2 and ZSM-12. The 2D -resolved spectra are used to develop a silicate framework structure refinement strategy based on Si-O, O-O, and Si-Si distance restraints and analytical relationships between local structure and Si chemical shifts and geminal couplings.
View Article and Find Full Text PDFJ Magn Reson
December 2024
Department of Chemistry and Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, MA 02139, USA. Electronic address:
We have prepared trityl radicals with protons at the positions of the -COOH group in the phenyl rings and examined their EPR spectra, which show large - hyperfine couplings, and their dynamic nuclear polarization (DNP) Zeeman field profiles . By assessing these polarizing agents for high-field and Overhauser effect DNP, we gain insight into the roles that these hyperfine couplings and other molecular properties play in the DNP performance of these radicals. Interestingly, we do not observe OE DNP in any of the three molecules we examined.
View Article and Find Full Text PDFJ Chem Theory Comput
November 2024
Donostia International Physics Center DIPC, Paseo Manuel Lardizabal 4, 20018 Donostia-San Sebastián, Spain.
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