Recrystallization in polyvinylidene fluoride upon low fluence swift heavy ion impact

Thin films (9 mum) of polyvinylidene fluoride (PVDF) are irradiated by swift 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 sharp 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 infrared (FTIR) absorbance intensities upon low fluence ion impact (10(10) ions/cm(2)). This increase in absorbance is in consonance with the simultaneous decrease of the transmission intensities of other crystalline bending vibration bands located at 532 (CF2 bending), 614, 796, and 975 cm(-1) (all due to CH2 bending) at the similar ion fluence. It appears most probable from the results that, being a polar polymer, the molecular dipoles in PVDF forming a hydrogen bond network get realigned upon irradiation into a highly ordered state of chain molecules in the crystalline regions and create volume elements as crystallites. (C) 2001 American Institute of Physics.