Phase transitions in gallium nanodroplets detected by dielectric spectroscopy

Both theoretical and experimental works give evidence that gallium exhibits solid phases labelled , , , besides the stable phase strongly dependent both on the size and the confinement conditions. An experimental technique was used based on capacitance and conductance measurements vs. temperature in the audiofrequency range. This technique is particularly sensitive to the conditions of the investigated particle surface that plays a fundamental role in the melting and more generally in the phase transition processes. In particular the strict relation between the derivative of the capacitance with respect to the temperature, dC/dT, and the entropy of the system is considered. In gallium nanoparticles 20 nm in radius, only the phase is shown to occur. Further the transition to liquid phase was detected. The melting process was found to start about 65 K below the full melting temperature value. In the case of particles 10 nm in radius, where different metastable phases may occur, the capacitance vs. temperature curve was found to display abrupt changes of the slope. The singularities are associated to a well defined transition temperature.     

Shot noise in a quantum dot coupled to carbon nanotube terminals applied with a microwave field

We have investigated the spectral density of shot noise for the system of a quantum dot (QD) coupled to two single-wall carbon nanotube terminals irradiated with a microwave field on the QD. The terminal features are involved in the shot noise through modifying the self-energy of QD. The contributions of carbon nanotube terminals to the shot noise exhibit obvious behaviors. The novel side peaks are associated with the photon absorption and emission procedure accompanying the suppression of shot noise. The shot noise in balanced absorption belongs to sub-Poissonian, and it is symmetric with respect to the gate voltage. The differential shot noise displays intimate relation with the nature of carbon nanotubes and the applied microwave field. It exhibits asymmetric behavior for the unbalanced absorption case versus gate voltage. The Fano factor of the system exhibits the deviation of shot noise from the Schottky formula, and the structures of terminals obviously contribute to it. The super-Poissonian and sub-Poissonian shot noise can be achieved in the unbalanced absorption in different regime of source-drain bias.     

Molecular Dynamics Simulation of Water Confined in Carbon Nanotubes

Molecular dynamics simulations are performed for water confined in carbon nanotubes with various diameters （11.0-13.8 A ）. The simulations under an isobaric pressure （one atmosphere） by lowering temperatures from 300 K to 190K are carried out. Water molecules within variously sized tubes tend to transform from disorder to order with different configurations （four-water-molecule ring, six-water-molecule ring and seven-water-molecule ring） at phase transition temperatures, which may be lowered by the increasing tube radius. It is also found that the configurations of water in （10, 10） tube are not unique （seven-molecule ring and seven-molecule ring plus water chain）.     

Quantum State Transfer in Trapped-Ion-Cavity Systems

We study the information transfer and entanglement transfer in a system consisting of single trapped ions in cavities by the three-mode cross-Kerr-like interaction among the cavity field （photons）, the centre-of-mass motion （phonons） and the internal state of the trapped ion in the Lamb-Dicke and large detuning regime.     

A Simple Model for Measuring Refractive Index of a Liquid Based upon Fresnel Equations

Due to many experimental data required and a lot of calculations involved, it is very complex and cumbersome to model prism-based liquid-refractive-index-measuring methods. We develop a new method of mathematical modelling for measuring refractive index of a liquid based upon the Fresnel formula and prism internal reflection at an incident angle less than the critical angle. With this method, only two different concentrations measurements for a kind of solution can lead to the determination of computational model. Measurements are performed to examine the validity of the theoretical model. Experimental results indicate the feasibility of the theoretical model with an error of 1%. The method is also capable of measuring even smaller changes in the optical refractive index of the material on a metal surface by the surface plasma resonance sensing techniques.     

Silver oligomer and single fullerene electronic properties revealed by a scanning tunnelling microscope

Clusters on surfaces have been investigated with low-temperature scanning tunnelling microscopy and spectroscopy. Constant current spectra acquired on Ag oligomers and one-dimensional chains on a Ag(111) reveal a single resonance peak whose energy shifts towards the Fermi level with increasing cluster size. Next, controlled and reproducible contact between a STM tip and a C₆₀ molecule adsorbed on Cu(100) is reported. The transition from tunnelling to contact is discussed in terms of local heating of the tip-molecule junction.     

Confined Ge–Pt states in self-organized Pt nanowire arrays on Ge(001)

By means of band structure calculations within the density functional theory and the generalized gradient approximation, we investigate the electronic structure of self-organized Pt nanowires on the Ge(001) surface. In particular, we deal with a novel one-dimensional surface state confined in the nanowire array and clarify its origin. Due to large Pt contributions, the novel state is rather a mixed Ge–Pt hybrid state than a confined Ge surface state. Moreover, we compare our results to data from scanning tunneling microscopy.     

Temperature dependent magnetic spin and orbital moments of mass-filtered cobalt clusters on Au(111)

Mass-filtered cobalt clusters with a size of 8 nm have been deposited in-situ under soft-landing conditions onto Au(111). The spin and orbital moments of the Co nanoparticles on a Au (111) single crystal have been investigated as a function of the temperature using the element-specific method of X-ray magnetic circular dichroism in photoabsorption. The results hint at an temperature-dependent spin-reorientation transition which is discussed with respect to different contribution to the magnetic anisotropy. Furthermore, by means of an in-situ oxidation experiment, the influence of an exposure to oxygen on the properties of the cobalt clusters has been investigated.     

Study of the gradual interface between hydroxyapatite thin films PLD grown onto Ti-controlled sublayers

Hydroxyapatite thin films were grown on layered structures by Pulsed Laser Deposition with the goal of investigating the interface of the ceramic film with the substrate. The latter consisted of Si/TiN/Ti sandwich structures. This multilayer substrate was also prepared by laser ablation earlier in the same experimental session.This particular type of structure was chosen in order to induce the in situ growth of hydroxyapatite directly onto freshly deposited Ti. We tried this way to avoid previous direct Ti exposure to air, hence its oxidation. The subsequent depositions of multilayers were performed with the aid of a carousel multi-target system mounted inside the irradiation chamber. This allowed for selecting in order the respective TiN, Ti and HA targets without opening the chamber between individual depositions.X-ray diffractometry, transmission electron microscopy and selected area electron diffractometry studies revealed the formation at the interface of a transition complex phase, 2 to 25 nm thick, consisting of a mixture of TiO₂ and CaP phase. The specific growth of TiN and Ti phases was also investigated.     

Viscous potential flow analysis of Kelvin-Helmholtz instability with mass transfer and vaporization

Viscous potential flow analysis of Kelvin-Helmholtz instability with heat and mass transfer has been studied. A dispersion relation has been obtained. Stability criterion is given by a critical value of relative velocity. It has been found that heat and mass transfer has destabilizing effect on relative velocity when lower fluid viscosity is low while it has stabilizing effect when lower fluid viscosity is high. Various graphs have been plotted for relative velocity and growth rate. In statically unstable situation viscosity has stabilizing effect while in statically stable situation it has destabilizing effect.