Soft X-ray radiation-damage studies in PMMA using a cryo-STXM

Radiation damage sets a fundamental limit for studies with ionizing radiation; cryo-methods are known to ease these limits. Here, measurements on mass loss and the decrease in the C=O bond density as measured by oxygen-edge XANES (NEXAFS) spectroscopy in thin films of poly(methylmethacrylate) (PMMA), studied in a vacuum, are reported. While cryo-methods allow more than 95% of the mass to remain at doses up to  Gy, there is little difference in C=O bond density versus dose between 298 K and 113 K sample temperatures. At both temperatures the critical dose for bond breaking is ∼15 × 10⁶ Gy.