Directional Supramolecular Polymerization in a Dynamic Microsolution: A Linearly Moving Polymer's End Striking Monomers.

Although directional chain reactions are common in nature's self-assembly processes and in covalent polymerizations, it has been challenging to perform such processes in artificial one-dimensional self-assembling systems. In this paper, we describe a system, employing perylene bisimide (PBI) derivatives as monomers, for selectively activating one end of a supramolecular polymer during its growth and, thereby, realizing directional supramolecular polymerization. Upon introduction of a solution containing only a single PBI monomer into the microflow channel, nucleation was induced spontaneously.

Quantum valence criticality in a correlated metal.

A valence critical end point existing near the absolute zero provides a unique case for the study of a quantum version of the strong density fluctuation at the Widom line in the supercritical fluids. Although singular charge and orbital dynamics are suggested theoretically to alter the electronic structure significantly, breaking down the standard quasi-particle picture, this has never been confirmed experimentally to date. We provide the first empirical evidence that the proximity to quantum valence criticality leads to a clear breakdown of Fermi liquid behavior.

Circular Dichroism Microscopy Free from Commingling Linear Dichroism via Discretely Modulated Circular Polarization.

In this work, we developed a circular dichroism (CD) imaging microscope with a device to suppress the commingling of linear birefringence (LB) and linear dichroism (LD) signals. CD signals are, in principle, free from the commingling influence of LD and LB if the sample is illuminated with pure circularly polarized light, with no linear polarization contribution. Based on this idea, we here propose a novel circular polarization modulation method to suppress the contribution of linear polarization, which enables high-sensitivity CD detection (10 level in optical density unit or mdeg level in ellipticity) for microscopic imaging at a nearly diffraction limited spatial resolution (sub-μm level).

Optical Activity Governed by Local Chiral Structures in Two-Dimensional Curved Metallic Nanostructures.

Chiral nanostructures show macroscopic optical activity. Local optical activity and its handedness are not uniform in the nanostructure, and are spatially distributed depending on the shape of the nanostructure. In this study we fabricated curved chain nanostructures made of gold by connecting linearly two or more arc structures in a two-dimensional plane.

Circular dichroism nano-imaging of two-dimensional chiral metal nanostructures.

Here we report on a nanoscale circular dichroism (CD) imaging for a two-dimensional chiral pair of nanostructures to elucidate the relationship between nanoscale chirality and CD activity. The chiral pair exhibited local ellipticity as high as 42 degrees in the CD signal at the center, with signals of both handedness coexisting in one nanostructure.

Raman enhancement by plasmonic excitation of structurally-characterized metal clusters: Au8, Ag8, and Cu8.

The optical responses of metal clusters, M8 (M = Au, Ag and Cu), are investigated by the linear response theory based on the density functional theory. Unlike sodium clusters [Yasuike et al., Phys.

Two-photon imaging of localized optical fields in the vicinity of silver nanowires using a scanning near-field optical microscope.

We report a near-field two-photon excitation imaging technique for silver nanostructures to visualize optical fields in the vicinity of nanostructures. We have found that the excitation image of an isolated wire shows an oscillating feature along the long axis of the wire. The period of the oscillation is in good agreement with that of plasmon wavefunctions resonant with the excitation light.

Visualization of localized intense optical fields in single gold-nanoparticle assemblies and ultrasensitive Raman active sites.

We demonstrate visualization of localized intense electromagnetic fields in real space in well-tailored dimeric and trimeric gold nanospheres by using near-field optical techniques. With two-photon induced luminescence and Raman measurements, we show that the electric field is confined at an interstitial site in the aggregate. We also demonstrate optical switching operations for the electric-field localized sites in the trimer structure.

An amphiphilic resin-supported palladium catalyst for high-throughput cross-coupling in water.

[reaction: see text] The Suzuki-Miyaura coupling of aryl halides (8 varieties) and aryl- or vinylboronic acids (12 varieties) took place in water in the presence of a palladium complex of an amphiphilic polystyrene-poly(ethylene glycol) copolymer resin-supported N-anchored 2-aza-1,3-bis(diphenylphosphino)propane ligand and potassium carbonate to give uniform and quantitative yields of the corresponding biaryls (96 varieties).