Temperature effect on gold nanodispersion in organic liquids

The temperature effect on gold nanodispersion in organic liquids was examined by optical absorption spectroscopy and transmission electron microscopy. It was found that the color of the dispersion changed from purple just after preparation under a low-temperature condition to reddish purple or pink with the elevation of temperature up to room temperature. The optical properties of this system strongly coupled with the state of dispersions such as isolation, coagulation, and coalescence to sediment. Heating the dispersion above room temperature induced the instability of the colloidal system which also resulted in the color change of the dispersion.