Application of scanning transmission X-ray microscopy for observation of organic compounds in toner particles

Toners for copy machines, printers, etc. are constructed of several kinds of resin, pigment, wax and other components. Transmission electron microscopy (TEM) has been used to study the dispersion of components in toners, but TEM imaging cannot easily distinguish various kinds of materials in toners. Scanning Transmission X-ray Microscopy (STXM) is a synchrotron-based analytical microscopy that uses carbon Is near edge X-ray absorption fine structure (NEXAFS) to identify organic compounds at sub-50 nm spatial resolution. The observation of toner particles and organic compounds was carried out by a STXM at the Advanced Light Source (ALS) in Berkeley, CA, U.S.A. Although staining methods made the TEM observation of wax possible, carbon black could not be observed simultaneously, STXM provides simultaneous observation of both species. Furthermore STXM can distinguish chemical components that have very similar NEXAFS and provide information on the dispersion of pigments by selected X-ray energy imaging. These results demonstrate the high capability of STXM to investigate the dispersion of organic compounds, thus aiding efforts for developing new, well-controlled toner.