Electron beam damage of perfluorosulfonic acid studied by soft X-ray spectromicroscopy

Publication date: Available online 7 March 2019Source: MicronAuthor(s): Lis G.A. Melo, Adam P. HitchcockAbstractScanning transmission X-ray microscopy (STXM) was used to study chemical changes to perfluorosulfonic acid (PFSA) spun cast thin films as a function of dose imparted by exposure of a 200 kV electron beam in a Transmission Electron Microscope (TEM). The relationship between electron beam fluence and absorbed dose was calibrated using a modified version of a protocol based on the positive to negative lithography transition in PMMA [Leontowich et al, J. Synchrotron Rad. 19 (2012) 976]. STXM was used to characterize and quantify the chemical changes caused by electron irradiation of PFSA under several different conditions. The critical dose for CF2-CF2 amorphization was used to explore the effects of the sample environment on electron beam damage. Use of a silicon nitride substrate was found to increase the CF2-CF2 amorphization critical dose by ˜x2 from that for free-standing PFSA films. Freestanding PFSA and PMMA films were damaged by 200 kV electrons at ˜100 K and then the damage was measured by STXM at 300 K (RT). The lithography cross-over dose for PMMA was found to be ˜2x higher when the PMMA thin film was electron irradiated at 120 K rather than at 300 K. The critical dose for CF2-CF2 amorphization in PFSA irradiated at 120 K followed by warming and delayed measurement by STXM at 300 K was found to be ˜2x larger than at 300 K. To place these results in the co...
Source: Micron - Category: Biology Source Type: research