Recrystallization in polyvinylidene fluoride upon low fluence swift heavy ion impact

Thin films (9 mum) of polyvinylidene fluoride (PVDF) are irradiated by swif t heavy ions (180 MeV Ag14+) in the fluence range 1x10(10)-1x10(12)ions/cm( 2) with an electronic linear energy transfer LET similar to 11 keV/nm. In s harp contrast to the previous results, the most characteristic crystalline asymmetric and symmetric "CH2" doublets (located at 3025 and 2985 cm(-1)), have shown remarkable increase in their respective Fourier transform infrar ed (FTIR) absorbance intensities upon low fluence ion impact (10(10) ions/c m(2)). This increase in absorbance is in consonance with the simultaneous d ecrease of the transmission intensities of other crystalline bending vibrat ion bands located at 532 (CF2 bending), 614, 796, and 975 cm(-1) (all due t o CH2 bending) at the similar ion fluence. It appears most probable from th e results that, being a polar polymer, the molecular dipoles in PVDF formin g a hydrogen bond network get realigned upon irradiation into a highly orde red state of chain molecules in the crystalline regions and create volume e lements as crystallites. (C) 2001 American Institute of Physics.