Solar-to-steam (STS) generation based on plasmonic materials has attracted significant attention as a green method for producing fresh water. Herein, a simple in situ method is introduced to fabricate Au nanoparticles (AuNPs) on cellulose filter papers as dual-functional substrates for STS generation and surface-enhanced Raman spectroscopy (SERS) sensing. The substrates exhibit 90% of broadband solar absorption between 350 and 1800 nm and achieve an evaporation rate of 0.
View Article and Find Full Text PDFHere, highly transparent nanocomposite films with an adjustable refractive index were fabricated through stable dispersion of ZrO ( = 2.16) nanoparticles (NPs) subjected to surface modification with SiO ( = 1.46) in polydimethylsiloxane (PDMS) ( = 1.
View Article and Find Full Text PDFPutrescine and cadaverine are important volatile indicators for the evaluation of food spoilage. In this study, a metal-organic framework (MOF)-coated surface-enhanced Raman scattering (SERS) paper platform for the detection of putrescine and cadaverine is developed. Au@ zeolite imidazolate framework-8 (ZIF-8) SERS paper is fabricated by the coating of ZIF-8 layer on a Au nanoparticle-impregnated paper that is prepared by dry plasma reduction.
View Article and Find Full Text PDFA newly developed nanopatterned broadband antireflective (AR) coating was fabricated on the front side of a glass/indium tin oxide/perovskite solar cell (PSC) by depositing a single interference layer onto a two-dimensional (2D)-patterned moth-eye-like nanostructure. The optimized developed AR nanostructure was simulated in a finite-difference time domain analysis. To realize the simulated developed AR nanostructure, we controlled the SiO moth-eye structure with various diameters and heights and a MgF single layer with varying thicknesses by sequentially performing nanosphere lithography, reactive ion etching, and electron-beam evaporation.
View Article and Find Full Text PDFMetal-assisted chemical etching (MACE) has been widely explored for developing silicon (Si)-based energy and optical devices with its benefits for low-cost and large-area fabrication of Si nanostructures of high aspect ratios. Surface structures and properties of Si nanostructures fabricated through MACE are significantly affected by experimental and environmental conditions of etchings. Herein, we showed that surfaces and interfacial energy states of fabricated Si nanowires can be critically affected by oxidants of MACE etching solutions.
View Article and Find Full Text PDFWe designed and fabricated a random-size inverted-pyramid-structured polydimethylsiloxane (RSIPS-PDMS) sticker to enhance the light absorption of solar cells and thus increase their efficiency. The fabricated sticker was laminated onto bare glass and crystalline silicon (c-Si) surfaces; consequently, low solar-weighted reflectance values were obtained for these surfaces (6.88 and 17.
View Article and Find Full Text PDFUltrasensitive nanomechanical instruments, including the atomic force microscope (AFM) and optical and magnetic tweezers, have helped shed new light on the complex mechanical environments of biological processes. However, it is difficult to scale down the size of these instruments due to their feedback mechanisms, which, if overcome, would enable high-density nanomechanical probing inside materials. A variety of molecular force probes including mechanophores, quantum dots, fluorescent pairs and molecular rotors have been designed to measure intracellular stresses; however, fluorescence-based techniques can have short operating times due to photo-instability and it is still challenging to quantify the forces with high spatial and mechanical resolution.
View Article and Find Full Text PDFPrecise positioning of a plasmonic nanoparticle (NP) near a small dielectric surface is not only necessary for understanding gap-dependent interactions between a metal and dielectric but it is also a critical component in building ultrasensitive molecular rulers and force sensing devices. In this study we investigate the gap-dependent scattering of gold and silver NPs by controllably depositing them on an atomic force microscope (AFM) tip and monitoring their scattering within the evanescent field of a tin dioxide nanofiber waveguide. The enhanced distance-dependent scattering profiles due to plasmon-dielectric coupling effects show similar decays for both gold and silver NPs given the strong dependence of the coupling on the decaying power in the near-field.
View Article and Find Full Text PDFA clear understanding of the mechanical behavior of nanometer thick films on nanostructures, as well as developing versatile approaches to characterize their mechanical properties, are of great importance and may serve as the foundation for understanding and controlling molecular interactions at the interface of nanostructures. Here we report on the synthesis of thin, compressible polyethylene glycol (PEG) monolayers with a wet thickness of <20 nm on tin dioxide (SnO2) nanofibers through silane-based chemistries. Nanomechanical properties of such thin PEG films were extensively investigated using atomic force microscopy (AFM).
View Article and Find Full Text PDFWe experimentally demonstrate that plasmonic nanoparticles embedded in the evanescent field of subwavelength optical waveguides (WGs) are highly sensitive to distances normal to the propagation of light, showing an ~10× increase in spatial resolution compared to the optical field decay of the WG. The scattering cross-section of the Au nanoparticle is increased by the plasmon-dielectric coupling interaction when the nanoparticle is placed near the dielectric surface of the WG, and the decay of the scattering signal is enhanced, showing angstrom level distance sensitivity within 10 nm from the WG. Numerical studies with the finite-difference time-domain (FDTD) method correlate well with the experimental results.
View Article and Find Full Text PDFHere we demonstrate a facile method of quantifying the decaying optical field surrounding free-standing tin dioxide (SnO(2)) nanofiber waveguides. Through the use of thin self-assembled polyelectrolyte coatings and fluorescent optical transmitters we map out the optical intensity as a function of distance with nanometer resolution.
View Article and Find Full Text PDFOptical antennas interface an object with optical radiation and boost the absorption and emission of light by the objects through the antenna modes. It has been much desired to enhance both excitation and emission processes of the quantum emitters as well as to interface multiwavelength channels for many nano-optical applications. Here we report the experimental implementation of an optical antenna operating in the full visible range via surface plasmon currents induced in a defect-free single-crystalline Ag nanowire (NW).
View Article and Find Full Text PDFWe report a systematic study of light coupling at junctions of overlapping SnO(2) nanofiber waveguides (WGs) as a function of gap separation and guided wavelength. The junctions were assembled on silica substrates using micromanipulation techniques and the gap separation was controlled by depositing thin self-assembled polyelectrolyte coatings at the fiber junctions. We demonstrate that the coupling efficiency is strongly dependent on the gap separation, showing strong fluctuations (0.
View Article and Find Full Text PDFWe report an ultrasensitive and selective single nanowire-on-film (SNOF) surface-enhanced resonance Raman scattering (SERRS) sensor for Hg(2+) detection based on structure-switching double stranded DNAs (dsDNAs). Binding of Hg(2+) induces conformational changes of the dsDNAs and let a Raman reporter get close to the SNOF structure, thereby turning on SERRS signal. The well-defined SNOF structure provides a detection limit of 100 pM with improved accuracy in Hg(2+) detection.
View Article and Find Full Text PDFWe report polymorph-tuned synthesis of α- and β-Bi(2)O(3) nanowires and their single nanowire micro-Raman study. The single crystalline Bi(2)O(3) nanowires in different phases (α and β) were selectively synthesized by adjusting the heating temperature of Bi precursor in a vapor transport process. No catalyst was employed.
View Article and Find Full Text PDFWe report that twin-free single-crystalline Pd nanowire (NW) arrays grow epitaxially in a selected pattern on a substrate. Parallel aligned Pd NWs are synthesized on a SrTiO(3) (110) substrate in a very high density. On a SrTiO(3) (001) substrate, Pd NWs grow horizontally in two perpendicular directions.
View Article and Find Full Text PDFA Au particle-on-wire system that can be used as a specific, sensitive, and multiplex DNA sensor is developed. A pattern formed by multiple Au nanowire sensors provides positional address and identification for each sensor. By using this system, multiplex sensing of target DNAs was possible in a quantitative manner with a detection limit of 10 pM.
View Article and Find Full Text PDFWe report a new type of molecular sensor using a Au nanowire (NW)-Au nanoparticles (NPs) conjugated system. The Au NW-NPs structure is fabricated by the self-assembly of biotinylated Au NPs on a biotinylated Au NW through avidin; this creates hot spots between NW and NPs that strongly enhance the Raman signal. The number of the Au NPs attached to the NW is reproducibly proportional to the concentration of the avidin, and is also proportional to the measured surface-enhanced Raman scattering (SERS) signals.
View Article and Find Full Text PDFFabricating well-defined and highly reproducible platforms for surface-enhanced Raman scattering (SERS) is very important in developing practical SERS sensors. We report a novel SERS platform composed of a single metallic nanowire (NW) on a metallic film. Optical excitation of this novel sandwich nanostructure provides a line of SERS hot spots (a SERS hot line) at the gap between the NW and the film.
View Article and Find Full Text PDFTyramine and its monohydrated clusters have been investigated by several laser spectroscopic methods in a pulsed molecular beam. The conformational structures and their effects on hydration have been revealed by resonant two-photon ionization (R2PI), UV-UV ion-dip, and ab initio calculations. UV rotational band contour spectra of the S1 <-- S0 origin bands enabled determination of ethylamine side chain conformations for all seven stable conformers of tyramine.
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