A new method of super cleaning for submicron particles in closed space (UV/photoelectron method) was developed. The charging and collecting unit employed either reflection-type photoelectron emitter or transmission-type one. The units mainly consisted of ultraviolet ray lamps, a photoelectron emitter and electrode. In this paper, characteristics and advantages of the units were studied. The mechanisms of particle charging and collection by the unit were also theoretically investigated. The particles received charges of negative ions generated by the photoelectron emission through the diffusion charging. The theoretical consideration on the deposition rate showed that the particle collection in the unit was achieved mainly by an electrophoresis of charged particles.