Mercury Nanodrops and Nanocrystals
mediaposted on 13.12.2011, 00:00 by G. V. Ramesh, Muvva D. Prasad, T. P. Radhakrishnan
Directed synthesis of stable mercury nanodrops and nanocrystals and exploration of their characteristic attributes are outstanding challenges, with the potential to unveil a new family of nanomaterials. The unique status of mercury among the chemical elements and metals, in particular, underlines the significance and perhaps explains the absence of any reports, so far, of such studies. A facile and simple protocol is developed for the generation of stable mercury nanodrops inside a polymer thin film, exploiting the in situ chemical reduction of precursor ions by the polymer itself under mild thermal annealing. The films exhibit the localized surface plasmon resonance absorption predicted for nano-mercury. Nanocrystals formed by freezing the nanodrops are observed directly and characterized using cryo-transmission electron microscopy and selected area electron diffraction of the free-standing nanocomposite thin film. Size dependence of the melting temperature is established by monitoring the electron diffraction in a variable-temperature experiment. Melt–freeze cycling reveals significant hysteresis effects. The mercury–polymer nanocomposite thin film is found to exhibit visible photoluminescence.