Synthesis, micro and electronic structure investigation of diamond nanorod spherules by High resolution NEXAFS coupled PEEM and field emission performance*

We report the synthesis of Diamond nanorods/flake Spherules (DNRS) predominantly consisting of UNCD enveloped by graphite in the form of flake or a rod with nanodimension, projecting randomly outward in all directions. The diamond nanoflake with a diameter of $\sim $2 nm has a central diamond (111) core encapsulated by graphitic (0002) lacing. The structure composition by High Resolution Transmission Electron Microscopy (HRTEM) and X ray Photoemission Electron Microscopy (XPEEM) revealed that the nanoflakes predominant with core sp$^{3}$ laced with sp$^{2}$, is embedded in carbon matrix consisting of other nanocarbon, such as the nanotubes, nanoonion and nanowires/sheets. High resolution localized XPEEM combined with XAS complimented the Raman and the XPS with a weak $\pi $* peak, a prominent exitonic and a second band dip, which are the signature of diamond. The congregated nanorod spherules exhibits a low-threshold, high current-density of 10 mA/cm$^{2}$ at 2.9 V/m which appears to be exceptional when compared to many other electron emitting nanostructures. Bias enhanced DNRS were also characterized by XPEEM and their FE's compared.