Raman spectroscopy of phenylcarbyne polymer films under pulsed green laserirradiation

The polycarbyne polymer films were coated on silicon substrates and then ir radiated by a pulsed Nd:yttrium-aluminum-garnet laser (lambda=532 nm) with various fluences in argon gas atmosphere. Significant changes in microstruc tures and chemical bonding (sp(3)/sp(2)) during laser treatment were invest igated by Raman spectroscopy. At a laser fluence below 50 mJ/cm(2), the Ram an spectrum of the film was similar to that of the original polymer film. I n a fluence range from 100 to 650 mJ/cm(2), the thermal decomposition of th e polymer occurred, resulting in upshift of G peak and downshift of the D p eak both with narrower peak width. With increasing laser fluence from 650 t o 950 mJ/cm(2), both the G and D peaks downshifted simultaneously due to th e thermal decomposition. The simultaneous downshift of both peaks indicated the increased sp(3)/sp(2) ratio in the carbon film converted from the poly mer. With increasing laser fluence in this range, the thermal decomposition also induced the narrowing of both peaks. The narrowing of both peaks indi cated the increased ordering of sp(3) and sp(2) bonding components in the c onverted carbon film. The scanning electron microscopy studies provided the further evidence. The carbon films converted from the polymer films may co ntain the highest sp(3) carbon bonding at laser fluences in the range from 850 to 1000 mJ/cm(2). (C) 2000 American Institute of Physics. [S0021-8979(0 0)00302-9].