The use of fluorescent particle image analysis to measure the surface profile and charge distribution of electrostatically deposited powder

A novel method for mapping the surface profile of electrostatically deposited powder is reported. The method employs the deposition of electrostatically charged, monodispersed fluorescent latex spheres (FLS) with 2.26 μm diameter on the surface before and after powder deposition. The surface of the substrates and the deposited powder layer is mapped by imaging the FLS with an epifluorescent microscope with a resolution of ±2 μm in the z-axis and ±5 μm in the x- and y-axes. Typically, a 1 cm×1 cm area is scanned at 1 mm intervals. The surface profiles are plotted using Origin 6 software for 3D presentation. The method is also applied to map surface charge distribution of the deposited powder layer. Application of this method to study surface charge distribution of individual particles is also discussed. The method provides an examination of surface profile and surface charge distribution in a microscopic scale not provided by atomic or electrostatic force microscopes, which are effective in the nanometer range