The electronic structures and magnetic properties of（Mn, N）-codoped Zn O are investigated by using the firstprinciples calculations. In the ferromagnetic state, as N substitutes for the intermediate O atom of the nearest neighboring Mn ions, about 0.5 electron per Mn^2＋ion transfers to the N^2-ion, which leads to the high-state Mn ions（close to ＋2.5）and trivalent N3-ions. In an antiferromagnetic state, one electron transfers to the N2-ion from the downspin Mn2＋ion,while no electron transfer occurs for the upspin Mn^2＋ion. The（Mn, N）-codoped Zn O system shows ferromagnetism,which is attributed to the hybridization between Mn 3d and N 2p orbitals.
Ultrawide ZnSe nanoribbons are synthesized by the simple thermal evaporation.The microstructure of ZnSe nanoribbons is characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),high-resolution TEM(HRTEM),photoluminescence(PL) and Raman spectrum.It is found that the strong emission near the band gap of ZnSe centered at 460 nm is obtained in these nanoribbons.More importantly,ZnSe nanoribbons can act as lasing emitting optical cavities.Raman studies indicate that the longitudinal optic(LO) and transverse optic(TO) phonon confinements of the ZnSe nanoribbons shift to lower frequency.
