Analyses of Raman spectra for Na-ion implanted polyacetylene

A study has been made of the structures of ion implanted high density polyacetylene by using laser Raman spectroscopy. Sodium ion implantation was performed with doses of 1 x 10(15), 1 x 10(16) and 1 x 10(17) ions/cm(2) at energies Of 50, 100 and 150 keV at room temperature. The Raman spectrum of an intact polyacetylene has two peaks at about 1500 and 1150 cm(-1), which are due to C=C stretching mode (vl) and a mixed mode (v3) of the CH bending and C-C single bond stretching vibration, respectively. Ion implantation causes the appearance of two new Raman peaks at about 1360 and 1585 cm(-1), which correspond to disordered graphite (D-peak) and graphite (G-peak), respectively. It is found that Raman spectra of implanted specimens at low or intermediate doses consist of four peaks: two original peaks and two developing peaks. In the case of high energy and high dose ion implantation, the Raman spectra have an asymmetric broad peak around 1550 cm(-1), which is almost the same as that observed from diamond-like carbon. From the variation of Raman spectra, it is concluded that ion implantation in polyacetylene with C=C linear chain structures generates graphitic structures to form diamond-like carbon. (C) 1998 Elsevier Science B.V. All rights reserved.