2008 NOV 24 - (VerticalNews.com) -- "We have studied photoluminescence (PL) spectrum and dynamics of the inner nanotubes in double-walled carbon nanotubes (DWNTs) and compared PL properties between DWNTs and single-walled carbon nanotubes (SWNTs). The PL peak energies of the inner tubes are redshifted from those of SWNTs with the same chiral indices," scientists writing in the journal Physical Review B report.

  "This PL redshift is enhanced with an increase in the inner tube diameter. The PL lifetime of DWNTs increases with a decrease in the inner tube diameter," wrote H. Hirori and colleagues, Kyoto University ...read more

  2008 NOV 24 - (VerticalNews.com) -- "We consider a system of two vertical lens-shaped quantum dots. The quantum dots have substantially different diameters in contrast to most of the investigated structures," researchers in Hsinchu, Taiwan report.

  "We demonstrate theoretically a possibility to relocate the ground-state electronic wave function from one dot to another by applying an external magnetic field along the structure's growth direction. The relocation correlates with the anticrossing behavior of the two lowest electronic energy states of the quantum dot molecule. This effect originates from a nonuniform diamagnetic shift for the electronic states located in different dots and generates unusual features of the magnetization and magnetic susceptibility of the system. At low temperature, the differential susceptibility of the system has a positive peak. With increasing temperature the peak gradually disappears," wrote O. Voskoboynikov and colleagues, National Chiao Tung University ...read more

  2008 NOV 24 - (VerticalNews.com) -- According to a study from Tokyo, Japan, "Eu3+-doped ZnO nanoneedles were fabricated by thermal evaporation. In order to include Eu in ZnO nanostructures, europium nitrate was used to produce starting droplets from which ZnO nanoneedles were grown."

  "Photoluminescence spectra included a sharp blue peak corresponding to the ZnO band gap and a broad red band due to defect states. In addition, sharp intra-4f transitions of Eu3+ ions were observed. Energy transfer from the ZnO matrix to Eu3+ was also observed. Study of the photoluminescence excitation revealed absorption tail states below the ZnO band gap induced by the inclusion of Eu ions in the ZnO nanoneedles," wrote K. Ebisawa and colleagues ...read more