Water adsorption to quantum dot surfaces was studied using paramagnetic relaxation enhancement of 1H NMR. Mn-doped and undoped CdS/ZnS core/shell quantum dots were synthesized and dispersed in d-benzene solutions. NMR analysis resulted in successful verification of the identity of a peak due to water at 0.5 ppm. Trends emerging from varying concentration of the nanoparticle and presence of dopant show an observable difference in the water signal. Doped and undoped particles alike show a downfield shift of the water signal of about 0.07 ppm compared to water in solvent alone (0.43 ppm), as well as broadening and shortening of the peaks. The broadening and shortening is further seen when increasing concentration of the quantum dot, and when comparing doped and undoped samples of the same concentration. Interest in possible temperature dependence led to additional tests at 313K, which resulted in changes in the intensity of the 0.5 ppm water peak.

Utilizing paramagnetic Mn-doping of CdS quantum dots to investigate surface water adsorption via NMR

245th National Meeting (2013)

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