Low-temperature positron annihilation study of B+-ion implanted PMMA

Международная научно-практическая конференция «Нанотехнологии и наноматериалы»<br>(Буковель, Украина, 29 августа–1 сентября, 2013 г.)

Анотація

Temperature dependent positron annihilation lifetime spectroscopy (PALS) measurements in the range of 50–300 K are carried out to study positronium formation in 40 keV B⁺-ion implanted polymethylmethacrylate(B:PMMA) with two ion doses of 3.13·10¹⁵ and 3.75·10¹⁶ ions/cm². The investigated samples show the varioustemperature trends of ortho-positronium (o-Ps) lifetime τ₃ and intensity I₃ in PMMA before and after ion implantation. Two transitions in the vicinity of ~150 and ~250 K, ascribed to γ and β transitions, respectively, are observed in the PMMA and B:PMMA samples in consistent with reference data for pristine sample. The obtained results are compared with room temperature PALS study of PMMA with different molecular weight (M_w) which known from literature. It is found that B⁺-ion implantation leads to decreasing M_w in PMMA at lower iondose. At higher ion dose the local destruction of polymeric structure follows to broadening of lifetime distribution (hole size distribution).