Luminescent ionic liquids are formed by the melting of tetranuclear rhenium(v) clusters.

We have investigated the emission of the terahertz electromagnetic wave from an undoped GaAs ͑200 nm͒ / n-type GaAs ͑3 m͒ epitaxial layer structure ͑i-GaAs/ n-GaAs structure͒, where the doping concentration of the n-GaAs layer is 3 ϫ 10 18 cm −3. It is found that the first-burst amplitude of terahertz wave of the i-GaAs/ n-GaAs sample is remarkably larger than that of a n-GaAs crystal, which means that the i-GaAs layer enhances the terahertz emission intensity. The first-burst amplitude of the i-GaAs/ n-GaAs sample, by tuning the pump-beam energy to the higher energy side, exceeds that of an i-InAs crystal that is known as one of the most intense terahertz emitters. We, therefore, conclude that the i-GaAs/ n-GaAs structure is useful to obtain intense terahertz emission.

The formation of porous structures of nanometre size (nanoporous structures) on germanium (Ge) surfaces by focused ion beam (FIB) irradiations was investigated using various FIB conditions such as ion species, irradiation energies, total fluences, fluence rates, and incident angles. FIB-irradiated regions were observed using a scanning electron microscope and an atomic force microscope. It is found that, using a focused Ga ion beam (Ga FIB) at an energy of 100 keV, the irradiated Ge surface swelled up to ion fluence of 2 × 10 17 cm −2 with nanoporous structures and then was etched for larger fluences. The shape of swollen nanoporous structures depended on the fluence rate and the incident angle of the Ga FIB. However, such porous structures were observed neither for low-energy (15-30 keV) FIB irradiations using Si and Au ions nor for high-energy (200 keV), heavy ion (Au) irradiation. These observations might be helpful in discussing the formation mechanisms of the nanoporous structures on Ge surfaces by ion beam irradiations. Fabrication of patterned structures at selected regions on the Ge surface was demonstrated without using any masks.

Two-dimensional Hofmann-type coordination polymers of type Mn­(H2O)2[Pd­(CN)4]·xH2O (1· x H 2 O; x = 0, 1, and 4), Mn­(H2O)­(MeOH)­[Pd­(CN)4]·2MeOH (2·2MeOH), and Mn­(MeOH)2[Pd­(CN)4]·MeOH (3·MeOH) have been synthesized. The homosolvent-bound 1·4H 2 O, 1·H 2 O, and 3·MeOH polymers consist of undulating layer structures, whereas the structure of heterosolvent-bound 2·2MeOH consists of “Janus-like” flat layers in which water-bound and MeOH-bound-sides are present. 1·4H 2 O and 1·H 2 O exhibited anisotropic two-dimensional thermal expansions involving structural transformations of the undulating layers; one layer axis expands while the other contracts. 2·2MeOH exhibits anisotropic thermal expansion in which the flat layers shift sideways as the temperature is increased, with colossal interlayer expansion occurring (αc = +200 MK–1 over 140–180 K, αc = +165 MK–1 over 200–280 K). 3·MeOH also showed colossal interlayer expansion (αc = +216 MK–1) together with expansion of the undulating layers.

Layer flexibility in two‐dimensional coordination polymers (2D‐CPs) contributes to several functional materials as it results in anisotropic structural response to external stimuli. Chemical modification is a common technique for modifying layer structures. This study demonstrates that crystal morphology of a cyanide‐bridged 2D‐CP of type [Mn(salen)]2[ReN(CN)4] (1) consisting of flexible undulating layers significantly impacts the layer configuration and assembly. Nanoplates of 1 showed an in‐plane contraction of layers with a longer interlayer distance compared to the micrometer‐sized rod‐type particles. These effects by crystal morphology on the structure of the 2D‐CP impacted the structural flexibility, resulting in dual‐functional changes: the enhancement of the sensitivity of structural transformation to water adsorption and modification of anisotropic thermal expansion of 1. Moreover, the nanoplates incorporated new adsorption sites within the layers, resulting in the uptake of an additional water molecule compared to the micrometer‐sized rods.