Experimental demonstration of metamaterial flat lens at F-band

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Hydrolysis of tetravalent cerium for a simple route to nanocrystalline cerium dioxide: an in situ spectroscopic study of nanocrystal evolution

Despite the rapid developments in recent nanocrystal research and their expanding applications, the evolution mechanism of nanocrystals remains veiled for the most part due to the lack of appropriate analytical techniques. Here we demonstrate one promising multi-spectroscopic approach for the in situ investigation of nanocrystal evolution. That is, the formation of nanocrystalline cerium dioxide (NC-CeO2) has been probed by dynamic light scattering (DLS), X-ray absorption spectroscopy (XAS) and high-energy X-ray scattering (HEXS). The obtained results indicate that the fine colloidal particles of NC-CeO2 are formed in an acidic aqueous solution simply through the hydrolysis of the initial precursor of small oligomer CeIV species. This information on how NC-CeO2 evolves is fundamental to simplifying and alleviating the synthetic strategy for NC-CeO2 production. © 2013, Wiley‐Vch Verlag

CW-THz vector spectroscopy and imaging system based on 1.55-mu m fiber-optics

We present a continuous-wave terahertz (THz) vector spectroscopy and imaging system based on a 1.5-mu m fiber optic unitraveling- carrier photodiode and InGaAs photo-conductive receiver. Using electro-optic (EO) phase modulators for THz phase control with shortened optical paths, the system achieves fast vector measurement with effective phase stabilization. Dynamic ranges of 100 dB.Hz and 75 degrees dB.Hz at 300 GHz and 1 THz, and phase stability of 1.5 per minute are obtained. With the simultaneous measurement of absorbance and relative permittivity, we demonstrate non-destructive analyses of pharmaceutical cocrystals inside tablets within a few minutes. (C) 2014 Optical Society of America111513sciescopu

Local coordination about La(3+) in molten LaCl3 and its mixtures with alkali chlorides.

The local structure around the La(3+) ions in molten LaCl(3) and its mixtures with alkali and alkaline earth chlorides has been investigated by using extended X-ray absorption fine structure (XAFS) and molecular dynamics (MD) techniques. Such mixtures, which are of current technological interest, are known to be thermodynamically nonideal, and there has been a good deal of work to understand the structural effects factors that contribute to the nonideality. New experimental methods allow observations at the La K-absorption edge at the high temperatures of interest, and the ability of the technique to obtain reliable information even at very low La(3+) concentrations in multicomponent mixtures is demonstrated. Both the mean La(3+)-Cl(-) interionic separation and the mean La(3+) coordination number are found to decrease as the concentration of La(3+) in the mixture decreases. The rate of decrease depends on the identity of the alkali and alkaline earth cations present in the mixtures in a way that parallels the degree of nonideality of the different systems; it is greatest for those alkali cations that coordinate Cl(-) weakly. In dilute mixtures with such cations La(3+) is able to adopt a very stable octahedral coordination geometry but this is inhibited by the presence of more strongly coordinating cations like Li(+) and Mg(2+)

Compact and stable THz vector spectroscopy using silicon photonics technology

We present a compact and stable terahertz (THz) vector spectroscopy system using silicon photonics technology. A silicon-based integrated phase control circuit greatly reduces the physical size of the continuous-wave THz spectroscopy system and enhances environmental phase stability. Differential lightwave phase control using two carrier-injection electro-optic modulators enables fast and linear phase sweeps of THz-waves. Using the silicon-photonic circuit, we demonstrate a THz vector spectrometer; the dynamic ranges are 65 and 35 dB at 300 GHz and 1 THz with 1-ms integration time and phase variation is less than similar to 10 degrees without thermal packaging. (c) 2014 Optical Society of America1113Nsciescopu