CONTROL OF STRUCTURES OF DEPOSITED POLYMER-FILMS BY ABLATION LASER WAVELENGTH - POLYACRYLONITRILE AT 308, 248, AND 193 NM

Extensive control of structures of deposited polymer films has been re alized when the films have been prepared on a quartz or KBr substrate by laser ablation of polyacrylonitrile (PAN) with 308 (XeCl), 248 (KrF ), and 193 nm (ArF) excimer laser beams, as revealed by scanning elect ron microscopy, infrared spectroscopy, x-ray photoelectron spectroscop y, electron spin resonance, and x-ray diffraction measurements. The or iginal structure of PAN is essentially retained for the films deposite d by ablation at 308 nm. Deformation and elimination of nitrile groups occur for the films prepared by ablation at 248 and 193 nm, respectiv ely. Furthermore, a remarkable power-dependent structural change has b een observed at 248 nm; an increase in the laser power has led to ring closure of nitrile groups, resulting in the development of pi-conjuga ted systems. In addition, a rather high electric conductivity on the o rder of 10(-2)S cm(-1) has been given to the films deposited by ablati on at 248 and 193 nm on reirradiation with lower-power excimer laser b eams of 308 nm. (C) 1996 American Institute of Physics.