Ultrathin supporting films in electron microscopy of unstained biological macromolecules.

: A simple technique is described, in which the increase in thickness of a carbon film is controlled. Films up to 10-15 A in thickness, which are both continuous and strong enough for use as supporting films in electron microscopy, can be easily obtained by this routine method. Images are shown of unstained ribosomial subunits and tropocollagen molecules on 15 A carbon films.