Reduction of thermal fluctuations in a cryogenic laser interferometric gravitational wave detector

The thermal fluctuation of mirror surfaces is the fundamental limitation for interferometric gravitational wave (GW) detectors. Here, we experimentally demonstrate for the first time a reduction in a mirror's thermal fluctuation in a GW detector with sapphire mirrors from the Cryogenic Laser Interferometer Observatory at 17 and 18 K. The detector sensitivity, which was limited by the mirror's thermal fluctuation at room temperature, was improved in the frequency range of 90 to 240 Hz by cooling the mirrors. The improved sensitivity reached a maximum of 2.2×10(-19) m/√Hz at 165 Hz.     

Liquid-liquid transition in supercooled water investigated by interaction with LiCl and Xe

The hypothesis that supercooled water consists of two distinct liquid phases has been explored on the basis of their ability to hydrate nonpolar (Xe) and electrolytic (LiCl) species. Xe incorporated in the bulk of amorphous solid water survives in the deeply supercooled regime above the glass-transition temperature of 136 K and is finally dehydrated at 165 K, whereas LiCl dissolves only in the liquid phase appearing above 165 K. The second liquid phase connects with normal water as inferred from high (poor) solubility of LiCl (Xe). This result also suggests that decoupling of translational diffusion and viscosity in the deeply supercooled regime is caused by domain structures of the two liquid phases formed during a possible liquid-liquid transition.     

Time-of-flight secondary ion mass spectroscopy analysis of Na adatoms interacting with water-ice film

The origins of a slow reaction rate between the sodium adatoms and the water-ice film have been investigated by analyzing the surface composition using time-of-flight secondary ion mass spectroscopy in the temperature range of 13-230 K. An unhydrated NaOH layer is formed at the water-Na interface at 13 K which is followed by the growth of the metallic Na layer, whereas domains of both NaOH and unreacted Na are created only in the multilayer regime at 100 K. The NaOH layer plays a role as a separator between the water and Na layers, and its poor solubility in water is responsible for the small reaction rate of Na on glassy water. The solubility of NaOH in the deeply supercooled liquid water is low as well, but the mobile water molecules diffusing to the surface react with the Na adatoms, thereby quenching the growth of the metallic Na overlayer.     

Metal‐ and Oxidant‐Free Alkenyl C−H/Aromatic C−H Cross‐Coupling Using Electrochemically Generated Iodosulfonium Ions

A three‐step transformation consisting of 1) addition of electrochemically generated iodosulfonium ions to vinylarenes to give (1‐aryl‐2‐iodoethoxy)sulfonium ions, 2) nucleophilic substitution by subsequently added aromatic compounds to give 1,1‐diaryl‐2‐iodoethane, and 3) elimination of HI with a base to give 1,1‐diarylethenes was developed. The transformation serves as a powerful metal‐ and chemical‐oxidant‐free method for alkenyl C?H/aromatic C?H cross‐coupling.     

p-type macroporous silicon having three-dimensional structure

Macroporous silicon with three-dimensional structure was fabricated using organic-based electrolyte, dimethylformamide (DMF), in the p-type silicon. The obtained three-dimensional macroporous structures grew wholly along the <100> orientation of the p-type silicon wafer.