Characterization of laser-produced plasma ions of various metals and their effect on the optical properties of the CR-39 polymer

The laser-produced plasma (LPP) ions of various metals (Mo, Ni, Cu, Ti and Zn) was implanted in CR-39 polymer, and their influence on its optical properties was investigated. The plasma of these metals was produced using 200 shots of a Q-switched Nd:YAG pulsed laser in a vacuum of 10-3 Torr. The CR-39 specimens were exposed to LPP ions (flux: F=8.01x109-22.14x109 ions/m2, average energy: E av=52-297 keV) emitted along the normal to the metal surface in each case. Both F and E av were found to be a function of the room temperature DebyeWaller thermal parameter B and increase with increase in B-value. The structural behavior of virgin and implanted specimens was investigated using a ultra violet (UV)visible spectrophotometer. The value of disorder content (Urbach energy E u) was found to lie in the range of 0.2870.377 eV. The optical band gap energy (E g) for indirect transition decreased on implantation with metallic LPP ions, whereas such a variation in the case of direct transition was negligible. It was observed that E g for indirect transition increases with the increase in E u, whereas the dependence of E g for direct transition on E u was negligible.