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This study utilizes atomic force microscopy and electrostatic force microscopy to investigate the orientation of overcrowded aromatics in films with submonolayer coverage. The results demonstrate that the side chains in the molecules can be used as a tool to control the molecular order and orientation in thin films. For molecules that do not self-associate well, the interaction with the substrate dominates, and the molecules orient with their aromatic planes parallel to the surface. These monolayers have measurable polar order. For molecules that self-associate well, the opposite orientation is observed. These films are comprised of isolated stacks of molecules parallel to the surface.
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http://dx.doi.org/10.1021/ja028524h | DOI Listing |
Phys Rev Lett
August 2025
Indian Institute of Science, Centre for Condensed Matter Theory, Department of Physics, Bengaluru 560 012, India.
We present a detailed analytical and numerical examination, on square and triangular lattices, of the nonreciprocal planar spin model introduced in Dadhichi et al. [Phys. Rev.
View Article and Find Full Text PDFPhys Rev Lett
August 2025
University of Konstanz, Department of Physics and Center for Applied Photonics, D-78457 Konstanz, Germany.
Femtosecond laser excitation of nanometer thin heterostructures comprising a heavy metal and a magnetically ordered material is known to result in the emission of terahertz radiation. However, the nature of the emitted radiation from heavy metal/antiferromagnet heterostructures has sparked debates and controversies in the literature. Here, we unambiguously separate spin and charge contributions from Pt/NiO heterostructures by introducing an unprecedented methodology combining high external magnetic fields with a symmetry analysis of the emitted terahertz polarization.
View Article and Find Full Text PDFAnal Sens
January 2025
Advanced Imaging Research Center, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX 75390 United States.
At present, two competing hyperpolarization (HP) techniques, dissolution dynamic nuclear polarization (DNP) and parahydrogen (para-H) induced polarization (PHIP), can generate sufficiently high liquid state C signal enhancement for in vivo studies. PHIP utilizes the singlet spin state of para-H to create non-equilibrium spin populations. In hydrogenative PHIP, para-H is irreversibly added to unsaturated precursors, typically in the presence of a homogeneous catalyst.
View Article and Find Full Text PDFLangmuir
September 2025
Federal University of São Paulo, Laboratory of Hybrid Materials, Diadema, São Paulo 09913-030, Brazil.
This study demonstrates the successful fabrication of nanostructured Langmuir-Blodgett (LB) films combining the conjugated copolymer poly(9,9-dioctylfluorene--3,4-ethylenedioxythiophene) (PDOF--PEDOT) with spherical and triangular silver nanoparticles (AgNP). The LB technique allowed precise control over the molecular arrangement and distribution of the nanoparticles at the air-water interface, resulting in compact, reproducible and structurally ordered nanocomposite films. The structural and morphological properties of the interfacial monolayers and LB films were investigated using surface pressure-area isotherms, Brewster angle microscopy, polarization modulation infrared reflection-absorption spectroscopy (PM-IRRAS) and quartz crystal microbalance.
View Article and Find Full Text PDFProc Natl Acad Sci U S A
September 2025
Department of Bioengineering, Stanford University, Stanford, CA 94305.
Despite periods of permanent darkness and extensive ice coverage in polar environments, photosynthetic ice diatoms display a remarkable capability of living inside the ice matrix. How these organisms navigate such hostile conditions with limited light and extreme cold remains unknown. Using a custom subzero temperature microscope during an Arctic expedition, we present the finding of motility at record-low temperatures in a Eukaryotic cell.
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