LAUSR

18 We present a superior approach to study quantitatively fine structure of C-doped ZnO 19 nanostructure using transmission electron microscopy (TEM) from which the role of carbon 20 in ZnO crystal to form ferromagnetism is revealed at the first time. Electron diffraction in 21 TEM shows Wurtzite structure in the nanoparticles with lattice parameters (a = 0.327  0.03 22 nm, and c = 0.529  0.04 nm) slightly different from the original structure. Interestingly, the 23 Zn-C bonding with a bonding length of 2.58 Å is experimentally determined using atomic pair 24 distribution function (PDF) calculated from electron diffraction data. Together with other 25 2 bonding, such as C-C, Zn-O obtained from the PDF, this demonstrates migration of C atoms 1 into ZnO crystal to substitute O vacancies. This is furthermore visualized by high-resolution 2 TEM image, and strongly supports the proposal of origin of ferromagnetism in the C-doped 3 ZnO nanoparticles where the s–p and p-p hybridizations formed by C2p Zn4s, and O2p – 4 C2p orbitals are believed to cause ferromagnetism. 5 6