The third-rank susceptibility tensor that describes the second-harmonic generation changes sign after an inversion operation indicating its sensitivity to twinning structures. Here, the far-field scattering patterns of second-harmonic radiation generated by single twinned and twin-free ZnO rods were shown. The patterns were successfully correlated with the twinning structures. A finite dipole-wire model was effectively employed to model the pattern. It indicated that the dark or bright fringes at the 0° scattering angle originated as a result of the destructive or constructive interference of spin-Hamiltonian waves emitted from each halves of the twinned or twin-free ZnO rod. Far-Field Second-Harmonic Fingerprint of Twinning in Single ZnO Rods. S.W.Liu, H.J.Zhou, A.Ricca, R.Tian, M.Xiao: Physical Review B, 2008, 77[11], 113311 (4pp)