Simultaneous measurement of liquid surface tension and contact angle by light reflection.

We present an optical method of simultaneous measurement of liquid surface tension, contact angle, and the curved liquid surface shape, which uses the light reflection from this liquid surface due to the wettability. When an expanded and collimated laser beam is incident upon the curved liquid surfaces vertically, the special light reflection pattern, which includes a dark central region and a bright field outside, was observed. A critical spot on the curved liquid surface was found, and the dark field distribution is related to both the width of incidence beam and this critical spot. In our experiment, the different dark field distribution patterns were recorded when the width of the incidence beam changed. The liquid surface tension, contact angle, and the liquid surface shape were measured simultaneously. The proposed method is a new effective tool for present wetting characterization methods.

Prediction of hypervalent molecules: investigation on MnC (M = Li, Na, K, Rb and Cs; n = 1-8) clusters.

New hypervalent molecules have emerged from a systematic exploration of the structure and bonding of MnC (M = Li, Na, K, Rb and Cs; n = 1-8) clusters via an unbiased CALYPSO structure investigation combined with density functional theory. The global minimum structures are obtained at the B3LYP/6-311+G* and CCSD(T)/6-311+G* levels of theory. The observed growth behavior clearly indicates that the ground state of MnC (M = Li, Na, K, Rb and Cs; n = 1-8) is transformed from a planar to a three-dimensional (3D) structure at n = 4. A maximum of six alkali atoms can be bound atomically to a carbon atom. The determination of the averaged binding energies Eb(n), fragmentation energies ΔE(n) and HOMO-LUMO energy gaps unambiguously supports the stability of M6C. This indicated conclusively that 6 is a magic Li-coordination number for C. The nature of bonding is further investigated by an insightful analysis of the highest occupied molecular orbital (HOMO) and the topology of chemical bonds for the most stable clusters. In the final step, electron localization functions (ELF) and density of states (DOS) are determined in order to consolidate the acquired information on the studied electronic structures.

High Temperature-Resistant Transparent Conductive Films for Photoelectrochemical Devices Based on W/Ag Composite Nanonetworks.

The traditional Ag nanowire preparation means that it cannot meet the demanding requirements of photoelectrochemical devices due to the undesirable conductivity, difficulty in compounding, and poor heat resistance. Here, we prepared an Ag nanonetwork with superior properties using a special template method based on electrospinning technology. The transparent conductive films based on Ag nanonetworks have good transmittance in a wide range from ultraviolet to visible. It is important that the films have high operability and are easy to be compounded with other materials. After compounding with high-melting-point W metal, the heat-resistance temperature of the W/Ag composite transparent conductive films is increased by 100 °C to 460 °C, and the light transmission and electrical conductivity of the films are not significantly affected. All experimental phenomena in the study are analyzed theoretically. This research can provide an important idea for the metal nanowire electrode, which is difficult to be applied to the photoelectrochemical devices.

Optical Properties of Ag Nanoparticle Arrays: Near-Field Enhancement and Photo-Thermal Temperature Distribution.

The near-field and photo-thermal properties of nanostructures have always been the focus of attention due to their wide applications in nanomaterials. In this work, we numerically investigate the near-field and photo-thermal temperature distribution in a nanoparticle array when the scattering light field among particles is considered. 'Hot spots', which represent strong electric field enhancement, were analyzed at the difference of the particle size, particle spacing and the polarization direction of the incident light. Interestingly, it is found that the position of the 'hot spots' does not rotate with the polarization direction of the incident light and always remains in the particle gaps along the line between particle centers. Moreover, the near-field is independent of the polarization in some special areas, and the factor of near-field enhancement keeps constant in these spots when the illumination polarization varies. As for photo-induced heating, our results show that both the temperature of the structure center and maximum temperature increase linearly with the particle number of the array while decreasing with the increase in particle spacing. This work provides some theoretical considerations for the near-field manipulation and photo-thermal applications of nanoarrays.

Probing the structures, electronic and bonding properties of multidecker lanthanides: Neutral and anionic Lnn(COT)m (Ln = Ce, Nd, Eu, Ho and Yb; n, m = 1, 2) complexes.

The ground state structures of neutral and anionic Lnn(COT)m (Ln = Ce, Nd, Eu, Ho and Yb; n, m = 1, 2) complexes have been identified by density functional theory. Ln(COT)1,20/- and Ln2(COT)20/- complexes are found to possess sandwich ground state structures in which Ln atoms and COT molecules are alternately stacked except for Nd2COT20/-. Our calculated AEA and VDE values show good agreement with the available experimental values, which validates that our obtained ground state structures are credible. Based on the frontier molecular orbitals, we find that the bond formation between the 4f electrons of Ln atoms and the π clouds of COT molecules is weak. Then, the bond strength within these complexes is further analyzed based on the topological analysis of electron density at bond critical point. By analyzing Hirshfeld charge, we find Lnn(COT)m0/- are charge-transfer complexes with weak bonding feature.