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Third harmonic generation (THG) has proven its value in surface and interface characterization, high-contrast bio-imaging, and sub-wavelength light manipulation. Although THG is observed widely in general solid and liquid substances, when laser pulses are focused at nanometer-level ultra-thin films, the bulk THG has been reported to play the dominant role. However, there are still third harmonics (TH) generated at the surface of the thin-films, not inside the bulk solid - so-called surface TH, whose relative contribution has not been quantitatively revealed to date. In this study, we quantitatively characterized the surface and bulk contributions of THG at ultra-thin β-GaO nanomembranes with control of both the laser and thin-nanomembranes parameters, including the laser peak power, polarization state, number of layers, and nanomembranes thicknesses. Their contributions were studied in detail by analyzing the TH from freestanding β-GaO nanomembranes compared with TH from β-GaO nanomembranes on glass substrates. The contribution of the TH field from the β-GaO-air interface was found to be 5.12 times more efficient than that from the β-GaO-glass interface, and also 1.09 times stronger than the TH excited at bulk 1-μm-thick β-GaO. Besides, TH from the β-GaO-air interface was found to be 20% more sensitive to the crystalline structure than that from the β-GaO-glass interface. This research work deepens our understanding of surface and bulk THG from crystalline materials and provides new possibilities towards designing highly efficient nonlinear optical materials for bio-imaging, energy-harvesting, and ultrafast laser development.
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http://dx.doi.org/10.1039/d1nr06259j | DOI Listing |
Sci Rep
August 2025
Institute of Physical Chemistry, Friedrich Schiller University Jena, 07743, Jena, Germany.
Here we report a novel platform for the detection of nucleocapsid (N) and receptor-binding domain (RBD) of spike (S) proteins of SARS-CoV-2 viruses using the surface plasmon resonance (SPR) technique. We demonstrate that the functionalization of SPR sensors with molecular 2D materials - 1 nm thick carbon nanomembranes (CNMs) significantly enhances sensitivity. CNMs terminated with azide linker (N-CNM) enable covalent bonding of SARS-CoV-2 antibodies for specific immobilization of the N- and S-proteins to the sensor surface.
View Article and Find Full Text PDFACS Appl Mater Interfaces
September 2025
Institute of Chemistry, Chemnitz University of Technology, Chemnitz 09107, Germany.
Voltage control of exchange bias (EB) is an important technological goal for low-power spintronic sensor and memory devices. The magneto-ionic (MI) approach for voltage-controlled EB is a promising strategy to achieve this goal, utilizing electrochemical reactions at low operational voltages. In typical MI devices, however, the sensitive EB layers are directly targeted by the electrochemical reactions, which often impairs reversibility.
View Article and Find Full Text PDFSci Robot
August 2025
Material Systems for Nanoelectronics, Chemnitz University of Technology, 09107 Chemnitz, Germany.
Modular microrobotics can potentially address many information-intensive microtasks in medicine, manufacturing, and the environment. However, surface area has limited the natural powering, communication, functional integration, and self-assembly of smart mass-fabricated modular robotic devices at small scales. We demonstrate the integrated self-folding and self-rolling of functionalized patterned interior and exterior membrane surfaces resulting in programmable, self-assembling, intercommunicating, and self-locomoting micromodules (smartlets ≤ 1 cubic millimeter) with interior chambers for onboard buoyancy control.
View Article and Find Full Text PDFAnal Chem
September 2025
Anhui Provincial International Science and Technology Cooperation Base for Major Metabolic Diseases and Nutritional Interventions, China Light Industry Key Laboratory of Meat Microbial Control and Utilization, School of Food and Biological Engineering, Engineering Research Center of Bio-process, Min
The controlled assembly of noble metal nanomaterials at water-oil interfaces holds significant potential for enhancing the sensitivity and stability of surface-enhanced Raman scattering (SERS) technology. However, developing highly efficient nanomaterial assembly techniques to create structures with controllable plasmonic hotspots and easily transferable functionalities remains a critical challenge. Herein, we propose a hydrophobic modification-enhanced float assembly strategy to fabricate an ultraelastic nanomembrane (UE-nanomembrane) by reducing adsorption kinetic barriers.
View Article and Find Full Text PDFWe present a table-top light source of continuously tunable quasi-monochromatic vacuum ultraviolet (VUV) coupled to a custom-built photoionization detector and demonstrate its capacity to induce photoionization in trace levels of volatile organic compounds at ambient saturated vapor pressure. A high-power pulsed monochromatic laser powers an optical parametric amplifier that subsequently feeds into two materials inducing consecutively second harmonic generation (SHG) and third harmonic generation (THG). While the SHG is obtained in a bulk BBO crystal, the THG originates from suspended SiO nanomembranes.
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