We display that the process of charge carriers' separation at molecular photocells is a complex phenomenon that is controlled by the cumulative action of Coulomb interaction for electron-hole pairs and LUMO-LUMO offset energies. By applying quantum scattering theory and the Lippmann-Schwinger equation, we provide a comprehensive framework of the device operation in which the operating molecular photocell is described by a wave function. We find that depending on the magnitude of offset energies, the electron-hole interaction can normally decrease or abnormally increase the charge separation yield. To rationalize the results, we benefit from the spectral information provided in the model. Our analysis helps to optimize molecular photocells operation.
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http://dx.doi.org/10.1063/1.5029491 | DOI Listing |
Phys Med Biol
January 2025
Institute of High Energy Physics Chinese Academy of Sciences, 19B Yuquan Road, Shijingshan District, Beijing, Beijing, Beijing, 100049, CHINA.
Objective: Timing calibration is essential for positron emission tomography (PET) system as it enhances timing resolution to improve image quality. Traditionally, positron sources are employed for timing calibration. However, the photons emitted by these sources travel in opposite directions, necessitating that positrons annihilate at multiple locations to collect coincidence data across a greater number of lines of response (LORs).
View Article and Find Full Text PDFPhys Chem Chem Phys
January 2025
Department of Chemistry and Biochemistry, Old Dominion University, Norfolk, Virginia 23529, USA.
Understanding the nature of π-stacking interactions is important to molecular recognition, self-assembly, and organic semiconductors. The stack bond order (SBO) model of π-stacking has shown that the conformations of dimers are found at orientations where the combinations of monomer MOs are overall bonding within the stack. DFT calculations show that parallel displaced minima found on the potential energy surface for the π-stacked dimers of pentacene and perfluoropentacene occur when the dimer MOs are constructed from combinations of monomer MOs with an allowed SBO.
View Article and Find Full Text PDFMed Sci Sports Exerc
January 2025
Energy Metabolism Section, National Institute of Diabetes, Digestive and Kidney Diseases, Diabetes, Endocrinology, and Obesity Branch, National Institutes of Health (NIH), Bethesda, MD.
Introduction: ActiGraph accelerometers are used extensively to objectively assess physical activity, sedentary behavior, and sleep. Here, we present an objective validation of five generations of ActiGraph sensors to characterize potential differences in output arising from changes to hardware or firmware.
Methods: An orbital shaker generated accelerations from 0 to 3700 milli-g in a randomized order to test the wGT3X-BT, GT9X, CentrePoint Insight Watch (CPIW) 1.
J Am Chem Soc
January 2025
Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210, United States.
Stacking interactions are a recurring motif in supramolecular chemistry and biochemistry, where a persistent theme is a preference for parallel-displaced aromatic rings rather than face-to-face π-stacking. This is typically explained in terms of quadrupole-quadrupole interactions between the arene moieties but that interpretation is inconsistent with accurate calculations, which reveal that the quadrupolar picture is qualitatively wrong. At typical π-stacking distances, quadrupolar electrostatics may differ in sign from an exact calculation based on charge densities of the interacting arenes.
View Article and Find Full Text PDFAcc Chem Res
January 2025
Department of Chemistry, University of California, Berkeley, California 94720, United States.
ConspectusThe electronic properties of atomically thin van der Waals (vdW) materials can be precisely manipulated by vertically stacking them with a controlled offset (for example, a rotational offset─i.e., twist─between the layers, or a small difference in lattice constant) to generate moiré superlattices.
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