No abstract

No abstract

No abstract

Photoluminescent properties from three types of Ti and TiO2 capped ZnO structures have been investigated with different surface/volume ratios. Interestingly, it was found that both of surface passivation and surface plasmon (SP) coupling could affect the enhancements of ultraviolet (UV) emissions in the Ti-capped ZnO, while the enhancement rates of UV emissions via SP coupling were much higher than those via surface-passivation modulation with the increasing surface/volume ratios. Upon the evaluation of the dependence of Purcell factor and electron densities, our results can be well explained through energy transfer between defect-related and SP-coupling emissions.

We have illustrated a new approach to fabricate two forms of AlN/ZnO heterostructures―AlN/ZnO coaxial nanotubular heterostructures (CNHs) and AlN-nanotube/ZnO-nanoparticles heterostructures (AlN/ZnO NPs). X-ray diffraction (XRD) and transmission electron microscopy (TEM) results show that ZnO nanotubes and nanoparticels have grown on the inner surface of amorphous and polycrystalline AlN shell layer, respectively. A possible growth mechanism on the formation of different AlN/ZnO heterostructures is given. Compared with bare ZnO nanofibers, AlN/ZnO CNHs exhibited remarkable enhanced ultraviolet (UV) emission, while AlN/ZnO NPs showed significant visible emission. With the aid of classical optical diffraction effect theory, it can be calculated that nanoscale luminescent materials have a higher external luminescent efficiency with increasing surface/volume ratio. The influence of carrier confinement effect and surface defects for the PL properties is also investigated in the AlN/ZnO heterostructures. In addition, the photoluminescent (PL) properties of AlN/ZnO CNHs with various AlN shell layers thickness are further discussed.

Recently, several observed anomalies in semileptonic B meson decays have implied hints of lepton flavor universal violation. Motivated by these inspiring results, we study the baryon decays b → (c)τ −ν τ which are mediated by b → u(c)τ −ν τ transitions at quark level in the Standard Model and different New Physics scenarios. In the framework of the extended Standard Model on assuming a general effective theory, we constrain the Wilson coefficients of the NP operators using the experimental measurement results for the Br(B

No abstract

No abstract