LIGHT-EMISSION FROM POLYMERS UNDER POSITRON AND ELECTRON-BOMBARDMENT

Light emission from polymers (anthracene dissolved in polystryrene) un der both low-energy positron and electron bombardment has been studied . Results show a clear difference between optical emissions induced by positrons and electrons. For positrons, a blue band and a weak sub-bl ue band are observed, while the blue band and a yellow band are induce d by electrons. The light emissions in the blue band are due to produc tion of electron-hole pairs for both electron and positron cases. The yellow band is interpreted as a secondary process, involving the excit ation of metastable states generated by the electron beam. The sub-blu e band, observed only under positron bombardment, is believed due to t ransitions to the electron vacancy generated by positron annihilation.