By means of continuous wave electron spin resonance (cw ESR) in the X and L bands, the spin exchange of series of different concentrations of the spin probes 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO), 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPOL), and 4-(trimethylamino)-2,2,6,6-tetramethylpiperidine-1-oxyl iodide (CAT-1) in H(2)O and D(2)O have been examined. The rate constants k(e) of the spin exchange have been determined by complete spectra simulations, as well as directly from hyperfine line broadenings and concentration depending line shifts. The obtained results showed a good agreement. Their respective differences {k(e)(H(2)O) - k(e)(D(2)O)} could be determined for the first time. They reflect the different influence of the solvents on the spin dynamics but confirm the decrease of the reaction rate in D(2)O, caused by the higher degree of order in this liquid. The spectroscopic and kinetic results presented in this paper establish a further kind of isotopic effect.
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http://dx.doi.org/10.1021/jp209755v | DOI Listing |
Nanoscale
January 2025
School of Instrumentation and Optoelectronic Engineering, Beihang University, Beijing 100191, China.
Low-frequency noise in detection systems significantly affects the performance of ultrasensitive and ultracompact spin-exchange relaxation-free atomic magnetometers. High frequency modulation detection helps effectively suppress the 1/ noise and enhance the signal-to-noise ratio, but conventional modulators are bulky and restrict the development of integrated atomic magnetometer modulation-detection systems. Resonant metasurface-based thin-film lithium-niobate (TFLN) active optics can modulate free-space light within a compact configuration.
View Article and Find Full Text PDFSci Rep
January 2025
Department of Applied Physics, School of Engineering Sciences, KTH Royal Institute of Technology, AlbaNova University Center, SE-10691, Stockholm, Sweden.
Non-trivial band topology along with magnetism leads to different novel quantum phases. When time-reversal symmetry is broken in three-dimensional topological insulators (TIs) through, e.g.
View Article and Find Full Text PDFJ Chem Theory Comput
January 2025
Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, U.K.
Density functional approximations can reduce the spin symmetry breaking observed for self-consistent field (SCF) solutions compared to Hartree-Fock theory, but the amount of exact Hartree-Fock (HF) exchange appears to be a key determinant in broken symmetry. To elucidate the precise role of exact exchange, we investigate the energy landscape of unrestricted Hartree-Fock and Kohn-Sham density functional theory for benzene and square cyclobutadiene, which provide paradigmatic examples of closed-shell and open-shell electronic structures, respectively. We find that increasing the amount of exact exchange leads to more local SCF minima, which can be characterized as combinatorial arrangements of unpaired electrons in the carbon π system.
View Article and Find Full Text PDFInorg Chem
January 2025
Department of Chemistry, Clemson University, Clemson, South Carolina 29634-0973, United States.
A new series of 222 adelite-type Co(GeO)(OH) ( = La-Sm) single crystals were grown by a high-temperature, high-pressure hydrothermal method (650 °C and 100 MPa). Single-crystal diffraction refinements yielded chiral one-dimensional (1D) chains of Co along the axis with an average 2.98 Å separation between Co centers in the [CoO(OH)] ribbon chains.
View Article and Find Full Text PDFJ Phys Chem A
January 2025
Department of Chemistry, University of Louisville, Louisville, Kentucky 40292, United States.
Triplet-triplet energy transfer (TEnT) is of particular interest in various photochemical, photobiological, and energy science processes. It involves the exchange of spin and energy of electrons between two molecular fragments. Here, quasi-diabatic self-consistent field solutions were used to obtain the diabatic states involved in TEnT.
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