FORMATION OF HIGH MASS CARBON CLUSTER IONS FROM LASER ABLATION OF POLYMERS AND THIN CARBON-FILMS

Three materials were studied by laser ablation/Fourier transform mass spectrometry, using 266 nm laser radiation: a copolymer of ethylene and tetrafluoroethylene (ETFE), polyphenylene sulfide (PPS), and a diamond-like carbon film (DLC). In each case, positive ion mass spectra exhibit primarily even-numbered, high mass carbon clusters ("fullerenes") of the type previously reported for graphite ablation. In the case of ETFE, a large C 60+ peak ("buckminsterfullerene") was observed. The polymer spectra showed a strong dependence on the number of laser pulses on one spot and the laser power density. For ETFE, the fullerene ion relative intensity first increases and then decreases as a function of the number of laser pulses. For the DLC film, fullerenes are observed with a single laser pulse on a fresh spot of the sample. The results are interpreted in terms of a gas phase growth model for the fullerene ion formation. © 1990 American Institute of Physics.