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Abstract: Kinetic behavior of cold 87Rb atoms in integrating sphere is presented under adiabatic release. Decay time of cold atom cloud is deduced by calculation of residual cold atom number evolution under adiabatic release and agrees well with our experimental observation. Number evolutions of residual cold atoms under different kinds of acceleration have been studied in detail. Sequence laser pulse cooling is key technique for the successive operation of cold atom clock. The process of laser pulse cooling is numerically simulated and fitted with experiments, optimized distribution of cooling and dead time to get enough cold atoms is put forward to satisfy the demand of cold atom clock. [Copyright &y& Elsevier]

The growth behavior and electronic and magnetic properties of Ag n Ti (n = 1–16) clusters have been studied by using density functional theory and unbiased structure prediction method. Geometry optimizations indicate that a Ti atom in low-energy Ag n Ti cluster occupies the highest coordination position. The growth of the ground state structure shows an obvious regularity. The infrared, Raman and photoelectron spectra of Ag n Ti isomers have been simulated and can be used for their structural identification in the future. The Ag n Ti clusters with 19 and 17 valence electrons are respectively the easiest to lose and obtain one electron. The stability and chemical activity of the most stable structures have been analyzed by means of the averaged binding energy, dissociation energy and the gap of energy level. It is found that the Ag 14 Ti cluster has greater stability and large energy gap and can be regarded as a superatom. Silver-titanium cluster as a CO adsorption material must have very small size or the concentration of Ti atoms must reach a certain value. The calculation of magnetic moment and charge distribution shows that the magnetic moment of Ti atom in Ag n Ti cluster increases almost completely for n = 1–8, and significantly decreases or quenches for n = 9–16. The charge transfer between Ti and Ag atoms is the main reason for the change of magnetic moment of Ti atom. • The growth of the ground state Ag n Ti cluster shows an obvious regularity. • Ag n Ti clusters with 19 and 17 valence electrons are the easiest to lose and obtain one electron. • Magic Ag 14 Ti cluster with a large energy gap can be considered a superatom. • The change of magnetic moment is closely related to charge transfer. [ABSTRACT FROM AUTHOR]

Abstract: The geometrical structures, relative stabilities, and magnetic moments of iron-doped gold clusters, Au n Fe (n =1–7), have been investigated using density functional method B3LYP and LanL2DZ basis set. Many low-lying isomers of the Au n Fe clusters are obtained along with their electronic states. The results show that the ground-state Au n Fe isomers possess a linear structure for n =1–2 and a planar structure for n =3–7. The relative stabilities of Au n Fe clusters for the ground-state structures are analyzed based on the averaged binding energies, fragmentation energies, second-order difference of energies, and HOMO–LUMO energy gaps. It is found that the Au2Fe and Au4Fe clusters are magic clusters with high chemical stability. The magnetic moment calculations for the ground-state Au n Fe clusters, which are magnetic, indicate that the total magnetic moment of the clusters is mainly localized on the Fe atom and two magic clusters are larger in total magnetic moments than others. [Copyright &y& Elsevier]