Hyperfine Coupling in Colloidal n-Type ZnO Quantum Dots: Effects on Electron Spin Relaxation

Electron spin relaxation dynamics in colloidal ZnO quantum dots containing additional delocalized conduction band electrons (n-type) have been studied using electron paramagnetic resonance (EPR) spectroscopy. Variation of the 67Zn (I = 5/2) nuclear isotope content within the quantum dots allows the effects of the electron−nuclear hyperfine interaction on spin−spin and spin−lattice relaxation dynamics to be explored. Long room-temperature spin−spin relaxation times of T 2 = 87 ns are observed in ZnO quantum dots almost completely depleted of 67Zn.