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:
“After reading Howitt’s account of the Australian gold-diggings one evening,... I asked myself why I might not be washing some gold daily, though it were only the finest particles,—why I might not sink a shaft down to the gold within me, and work that mine.... At any rate, I might pursue some path, however solitary and narrow and crooked, in which I could walk with love and reverence.”
—Henry David Thoreau (1817–1862)