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Liquid-phase transmission electron microscopy is a burgeoning experimental technique for monitoring nanoscale dynamics in a liquid environment, increasingly employing microfluidic reactors to control the composition of the sample solution. Current challenges comprise fast mass transport dynamics inside the central nanochannel of the liquid cell, typically flow cells, and reliable fixation of the specimen in the limited imaging area. In this work, we present a liquid cell concept – the diffusion cell – that satisfies these seemingly contradictory requirements by providing additional on-chip bypasses to allow high convective transport around the nanochannel in which diffusive transport predominates. Diffusion cell prototypes are developed using numerical mass transport models and fabricated on the basis of existing two-chip setups. Important hydrodynamic parameters, i.e., the total flow resistance, the flow velocity in the imaging area, and the time constants of mixing, are improved by 2-3 orders of magnitude compared to existing setups. The solution replacement dynamics achieved within seconds already match the mixing timescales of many ex-situ scenarios, and further improvements are possible. Diffusion cells can be easily integrated into existing liquid-phase transmission electron microscopy workflows, provide correlation of results with ex-situ experiments, and can create additional research directions addressing fast nanoscale processes.In liquid-phase TEM, microfluidic reactors are used to monitor nanoscale (electro)chemical dynamics in liquid environments. Here, the authors develop a reactor design with accelerated mass transport, facilitating quantitative in-situ and in-operando studies. [ABSTRACT FROM AUTHOR]

Polaritons—hybrid light-matter excitations—enable nanoscale control of light. Particularly large polariton field confinement and long lifetimes can be found in graphene and materials consisting of two-dimensional layers bound by weak van der Waals forces1,2 (vdW materials). These polaritons can be tuned by electric fields3,4 or by material thickness5, leading to applications including nanolasers6, tunable infrared and terahertz detectors7, and molecular sensors8. Polaritons with anisotropic propagation along the surface of vdW materials have been predicted, caused by in-plane anisotropic structural and electronic properties9. In such materials, elliptic and hyperbolic in-plane polariton dispersion can be expected (for example, plasmon polaritons in black phosphorus9), the latter leading to an enhanced density of optical states and ray-like directional propagation along the surface. However, observation of anisotropic polariton propagation in natural materials has so far remained elusive. Here we report anisotropic polariton propagation along the surface of α-MoO3, a natural vdW material. By infrared nano-imaging and nano-spectroscopy of semiconducting α-MoO3 flakes and disks, we visualize and verify phonon polaritons with elliptic and hyperbolic in-plane dispersion, and with wavelengths (up to 60 times smaller than the corresponding photon wavelengths) comparable to those of graphene plasmon polaritons and boron nitride phonon polaritons3-5. From signal oscillations in real-space images we measure polariton amplitude lifetimes of 8 picoseconds, which is more than ten times larger than that of graphene plasmon polaritons at room temperature10. They are also a factor of about four larger than the best values so far reported for phonon polaritons in isotopically engineered boron nitride11 and for graphene plasmon polaritons at low temperatures12. In-plane anisotropic and ultra-low-loss polaritons in vdW materials could enable directional and strong light-matter interactions, nanoscale directional energy transfer and integrated flat optics in applications ranging from bio-sensing to quantum nanophotonics. Observation of the anisotropic propagation of polaritons along the surface of layered, semiconducting α-MoO3 confirms the existence of this phenomenon in natural materials. [ABSTRACT FROM AUTHOR]

Efficient doping of organic semiconductors is an important prerequisite for the fabrication of high performance organic electronic devices. In this work, we describe a novel single precursor low-temperature (70 °C) vapor phase infiltration (VPI) process to dope poly(3-hexyl)thiophene (P3HT). The infiltration is performed with the metal containing atomic layer deposition (ALD) precursor MoCl5. The conductivities of the polymer are assessed with four-point probe measurements and showed significant enhancement by up to 5 orders of magnitude, confirming the efficiency of the VPI process. The chemical changes resulting from the infiltration of P3HT are characterized by applying UV-Vis-NIR, Raman spectroscopy, and FTIR. The crystalline state of the material is analyzed by X-ray diffraction (XRD). SEM micrographs and AFM images show that the morphologies of the samples before and after the MoCl5 infiltration process do not seriously change. TEM images of cross-sections of the thin film clearly show that the vapor phase infiltration process results in the incorporation of Mo into the bulk of the polymer. [ABSTRACT FROM AUTHOR]

Coalescence and interdiffusion during film formation of waterborne polymers stabilized by commercial high T alkali-soluble resins (ASRs) were evaluated through environmental scanning electron microscopy and fluorescence resonance energy transfer. The observed effects were used to justify the mechanical properties. The presence of a hard barrier between particles that increased the coalescence temperature and hindered interdiffusion was responsible for the poor properties of the films casted at room temperatures and the enhanced behaviour when films were annealed at much higher temperatures. [ABSTRACT FROM AUTHOR]

Several ionic fullerene salts have been prepared based on a fulleropyrrolidine pyridinium cation and four different anions. The initial ionic fullerene can be easily prepared by quaternization of a pyridine-appended fulleropyrrolidine derivative in high yield. Anion exchange is a simple procedure giving several different salts of varying polarity. In addition to their characterization, the quantitative solubility of these salts has been studied in seven different solvents, including an imidazolium ionic liquid. [ABSTRACT FROM AUTHOR]

Abstract  The synthesis and characterisation of gold nanorods have been carried out by reduction of the gold salt HAuCl4. This has been done using a single reducing agent, acetylacetone, rather than the two reducing agents, sodium borohydride and ascorbic acid, normally required by standard wet chemistry methods of gold nanorod formation. Using this novel method, the nanorods were synthesised at several different pH values which were found to greatly affect both the rate at which the nanorods form and their physical dimensions. The concentrations of acetylacetone and silver nitrate used relative to the gold salt were found to alter the aspect ratio of the nanorods formed. Rods with an average length of 42 nm and an aspect ratio of 4.6 can be easily and reproducibly formed at pH 10 using this method. Nanorods formed under optimum conditions were investigated using TEM. [ABSTRACT FROM AUTHOR]