ELECTRONIC SPUTTERING OF CARBON CLUSTERS FROM ION-BEAM IRRADIATED ORGANIC FILMS

Positive ions of even numbered carbon clusters C2n+ (n > 20) are eject ed as a result of the interaction of fast MeV ions with poly(vinyliden e fluoride) (PVDF). Experiments provide circumstantial evidence that t hese ejected carbon clusters have a three-dimensional structure, consi sting of pentagons and hexagons, i.e. they are fullerenes. We have stu died the effect of macroscopic carbonisation induced by ion bombardmen t on the ejection of carbon cluster ions (C(n)+, n = 1-33; C2n+ , n = 21-50) from PVDF. Damage cross-section values are extracted from the f luence dependence of the secondary ion yields. The yield of fullerene ions from PVDF decreases as a function of MeV ion fluence. Accordingly , macroscopic carbonisation of the polymer is detrimental and is not a prerequisite to fullerene emission, confirming earlier findings that these carbon clusters are formed and ejected in a single MeV ion impac t basis. For comparison, the sputtering of carbon cluster ions origina ting from films of poly(tetrafluorethylene), poly(styrene), poly(ethyl ene terephthalate) and fluorinated fullerene have also been studied.