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 Zn-67 (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 Zn-67.