Spatial, energy, and time-dependent effects induced by surface charging of conductive and nonconductive samples have been studied by spectroscopic and microscopic techniques. Surface charging of indium-tin oxide and cesium iodide has been studied by atomic force microscopy with a conducting tip and photoemission electron microscopy. Intensity fluctuations of the photoemission spectra recorded on amorphous and crystalline silicon nitride are also presented. The consequence of such effects on the determination of local physical and chemical properties of insulating materials is discussed. (c) 2007 American Institute of Physics.