Charge Accumulation Properties in Saturated and Aromatic Hydrocarbons by Electron Beam Irradiation

In order to investigate the different properties of electric charge accumulation by electron beam irradiation between a saturated hydrocarbon and an aromatic hydrocarbon, an electron affinity and a trap depth for both hydrocarbons were calculated by using Molecular Orbital method. From calculated results, the relationship among a vacuum level, a conduction level, an ionization level, an electron affinity and a trap depth were drawn in an energy diagram for both saturated and aromatic hydrocarbons. Basically, there was a negative electron affinity for saturated hydrocarbon such as Polyethylene (PE), Polypropylene (PP) and Polystyrene (PS). On the other hand there was a positive electron affinity for aromatic hydrocarbon such as Polycarbonate (PC), Polyethyleneterephthalate (PET), Polyethylenenaphthalate (PEN), and Polyimide (PI). It was found that the conduction level of electric carrier for saturated hydrocarbon was higher than a vacuum level, however the conduction level for aromatic hydrocarbon was the same as the vacuum level. Furthermore, from the results of electro static potential distribution calculated by Molecular Orbital method, it was clearly found that the excess electron in polymeric material was trapped around a carbonyl radical and benzene ring which have a large electric dipole.