Abstract: A photoemissive ion mobility spectrometer is disclosed for of chlorinated hydrocarbons and nitro-organic materials. Backside illumination of a thin gold film by pulsed laser radiation, pulsed ultraviolet xenon flashlamp, or like UV source, is used to produce bursts of low energy photo-emitted electrons. These swarms of thermalized electrons are directly attached by electronegative analytes or by reactant molecules, followed by charge transfer to the more electronegative analyte. Total internal reflection is incorporated for the backside illumination using optical elements such as a fused silica prism. The spectrometer allows for the direct vaporization of adsorbed explosive molecules from surfaces followed by direct injection into the photoemissive ion mobility spectrometer through a heated inlet.