Origin and scaling of the permanent dipole moment in CdSe nanorods.

Transient electric birefringence measurements were performed on dilute solutions of CdSe nanorods. The results confirm the existence of a permanent dipole along the c-crystallographic axis. Measurements on nanorods with different widths and lengths show that the longitudinal permanent dipole moment scales linearly with volume, suggesting it arise from the noncentrosymmetric crystallographic lattice.