Mechanically induced defects in milled CdZnSe nanocrystal: A low-temperature electron spin resonance spectroscopy analysis

The electron spin resonance (ESR) linewidth of the milled powder decreases as a function of increasing temperature. On the other hand, the intensity of the signal increases with increasing temperature from 108K to 243K and subsequently approaches Curie-like temperature behavior above 245K. These behaviors were understood in terms of the orbital degeneracy of fast-relaxing impurities, such as Fe3+ ion debris, from the grinding media that was embedded in the atomic structure of the milled powder and are not completely quenched. At lower temperature, only ±1/2 is occupied and the excited energy state is less likely effective in dipolar broadening compared with lower energy states of ±5/2 and ±3/2. In this regard, decrease in linewidth should be expected with increasing temperature.