Single crystal

About: Single crystal is a research topic. Over the lifetime, 59617 publications have been published within this topic receiving 870828 citations.

The fourth crystallographic closest packing unveiled in the gold nanocluster crystal

Abstract: Metal nanoclusters have recently attracted extensive interest not only for fundamental scientific research, but also for practical applications. For fundamental scientific research, it is of major importance to explore the internal structure and crystallographic arrangement. Herein, we synthesize a gold nanocluster whose composition is determined to be Au60S6(SCH2Ph)36 by using electrospray ionization mass spectrometry and single crystal X-ray crystallography (SCXC). SCXC also reveals that Au60S6(SCH2Ph)36 consists of a fcc-like Au20 kernel protected by a pair of giant Au20S3(SCH2Ph)18 staple motifs, which contain 6 tetrahedral-coordinate μ4-S atoms not previously reported in the Au-S interface. Importantly, the fourth crystallographic closest-packed pattern, termed 6H left-handed helical (6HLH) arrangement, which results in the distinct loss of solid photoluminescence of amorphous Au60S6(SCH2Ph)36, is found in the crystals of Au60S6(SCH2Ph)36. The solvent-polarity-dependent solution photoluminescence is also demonstrated. Overall, this work provides important insights about the structure, Au-S bonding and solid photoluminescence of gold nanoclusters.

Surface Monocrystallization of Copper Foil for Fast Growth of Large Single-Crystal Graphene under Free Molecular Flow

Abstract: Wafer-sized single-crystalline Cu (100) surface can be readily achieved on stacked polycrystalline Cu foils via simple oxygen chemisorption-induced reconstruction, enabling fast growth of large-scale millimeter-sized single-crystalline graphene arrays under molecular flow. The maximum growth rate can reach 300 μm min-1 , several orders of magnitude higher than previously reported values for millimeter-sized single-crystalline graphene growth on Cu foils.

A single-crystal neutron diffraction study of the temperature dependence of hydrogen-atom disorder in benzoic acid dimers

Abstract: Hydrogen-atom transfer across the hydrogen bonds of benzoic acid dimers has been studied previously by spectroscopic and X-ray methods, but no high-resolution neutron single crystal structures have ever been reported. The system is of interest because the hydrogen-atom dynamics change from classical Arrhenius behaviour to phonon-assisted quantum tunnelling as a function of decreasing temperature. Here we present a series of neutron single-crystal structure refinements at five temperatures ranging from 175 K, where Arrhenius behaviour holds, down to 20 K, where translational tunnelling is dominant. The refinements yield accurate atomic coordinates, thermal parameters and site occupancy factors for all atoms, and show that conversion of the B dimer configuration to the lower energy A dimer configuration in the range 175 to 50 K is primarily enthalpy driven, in good agreement with spectroscopic data. Site occupancies for the hydrogen-bonded hydrogen atom at 20 K do not fit the trend in occupancies observed at the four higher temperatures, and a further series of structure refinements at temperatures below 50 K is planned to investigate this.