Utility of the G value and the critical dose to soft X-ray radiation damage of polyacrylonitrile

The sensitivity of organic matter to ionizing radiation is often reported in terms of a G value, or a critical dose value. In several reports which document the radiation sensitivity of organics, the response of a material to absorbed dose is shown to display first-order kinetics (i.e. exponential decay), and subsequently both a G value and a critical dose value are derived from the data. In this report the response of a thin film of polyacrylonitrile to increasing doses of 300 eV soft X-rays was measured in the C 1s near edge X-ray absorption fine structure (NEXAFS) region using a scanning transmission X-ray microscope (STXM). The C 1s(C≡N)→π⁎C≡N feature displayed exponential decay. Both a G value(s) and a critical dose value are derived, and the utility of each descriptor is discussed.