Positron annihilation sites in nano lead sulfide powders

The coincident Doppler broadening of the positron-electron annihilation radiation has been applied for the identification of vacancies in nano lead sulfide (nano-PbS) powders. The results of the positron annihilation studies on nano-PbS with different particle size are presented. Nano-PbS specimens have been synthesized by the chemical bath deposition in aqueous medium. Independently of the size of nanoparticles (from 12 to 16 nm) the positron lifetime (PLT) for all specimens has been found to be the same and equal to 391 +/- 1 ps. Independently of the size of nanoparticles the chemical surrounding of positron annihilation sites identified by coincident Doppler broadening measurements was the same, namely lead (Pb).