Colloidal gold is a suspension (or colloid) of sub-micrometre-sized particles of gold in a fluid — usually water. The liquid is usually either an intense red colour (for particles less than 100 nm), or a dirty yellowish colour (for larger particles). Due to the unique optical, electronic, and molecular-recognition properties of gold nanoparticles, they are the subject of substantial research, with applications in a wide variety of areas, including electron microscopy, electronics, nanotechnology, and materials science.
Properties and applications of colloidal gold nanoparticles strongly depend upon their size and shape. For example, rodlike particles have both transverse and longitudinal absorption peak, and anisotropy of the shape affects their self-assembly.
Read more about Colloidal Gold: History, Synthesis, Electron Microscopy
Famous quotes containing the word gold:
“Having behind us the producing masses of this nation and the world, supported by the commercial interests, the labor interests, and the toilers everywhere, we will answer their demand for a gold standard by saying to them: You shall not press down upon the brow of labor this crown of thorns, you shall not crucify mankind upon a cross of gold.”
—Administration in the State of Neva, U.S. public relief program (1935-1943)