Single crystals of sodium containing silicon clathrate compounds Na8Si46 (type I) and NaxSi136 (type II) were prepared from the mixtures of NaSi and Si under high-pressure and high-temperature conditions of 5 GPa at 600-1000 °C. The type II crystals were obtained at relatively low-temperature conditions of 700-800 °C, which were found to have a Na excess composition Na30.5Si136 in comparison with the compounds NaxSi136 (x ≤ 24) obtained by a thermal decomposition of NaSi under vacuum. The single crystal study revealed that the Na excess type II compound crystallizes in space group Fd3̅m with a lattice parameter of a = 14.796(1) Å, slightly larger than that of the ambient phase (Na24Si136), and the large silicon hexakaidecahedral cages (@Si28) are occupied by two sodium atoms disordered in the two 32e sites around the center of the @Si28 cages. At temperatures <90 K, the crystal symmetry of the compound changes from the face-centered to the primitive cell with space group P213, and the Na atoms in the @Si28 cages are aligned as Na2 pairs. The temperature dependence of the magnetic susceptibility of Na30.5Si136 suggests that the two Na ions (2 Na(+)) in the cage are changed to a Na2 molecule. The Na atoms of Na30.5Si136 can be deintercalated from the cages topochemically by evacuation at elevated temperatures. The single crystal study of the deintercalated phases NaxSi136 (x = 25.5 and 5.5) revealed that only excess Na atoms have disordered arrangements.

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We demonstrated a new plasmonic nanodevice that spatially sorts photons according to their colors on the nanoscale while maintaining their nanoconcentration. The properties of this nanoscale color sorting based on constructive and destructive interferences between different multipolar plasmon modes are controlled by tuning the incidence angle of the incoming photons. The added ability of color sorting and its manipulation could significantly influence the development of possible photonic applications, including nanoscale spectroscopy and sensing.

A novel method for optical lithography using a resist with nonlinear photosensitivity and the multiple exposure technique is described. By means of this method, the diffraction-limited optical cutoff frequency is raised markedly, which cannot be realized by any of the other methods proposed previously. A brief explanation of the principle is given and computer simulations are demonstrated.

Single crystals of clathrate compounds Na 8Si 46 (type I) and Na30.5Si136 (type II) are prepared from mixtures of NaSi and Si in a molar ratio of 1:4 under 5 GPa at 1000 and 800 C, respectively. As revealed by single crystal XRD, Na30.5Si136 crystallizes in the space group Fd3m with Z = 4. The large silicon hexakaidecahedral cages are occupied by two sodium atoms (Na 2@Si28) disordered around the center of the Si28 cages. At temperatures < 90 K, the crystal symmetry of the compound changes from a face-centered to a primitive cell with space group P213 (Z = 4). Magnetic susceptibility measurements as a function of temperature suggest that the two Na ions in the cage change to a Na 2 molecule. The Na atoms of Na30.5Si136 can be deintercalated from the cages by evacuation at elevated temperatures. -(YAMANAKA*, S.; KOMATSU, M.; TANAKA, M.; SAWA, H.; INUMARU, K.; J. Am. Chem. Soc. 136 (2014) 21, 7717-7725, http://dx.