Radiation damage in soft X-ray microscopy |
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Authors: | J. Wang C. Morin L. Li A.P. Hitchcock A. Scholl A. Doran |
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Affiliation: | aDepartment of Chemistry and Brockhouse Institute for Materials Research, McMaster University, Hamilton, ON, Canada L8S 4M1;bAdvanced Light Source, Berkeley Lab, Berkeley, CA 94720, United States |
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Abstract: | The rates of chemical transformation by radiation damage of polystyrene (PS), poly(methyl methacrylate) (PMMA), and fibrinogen (Fg) in a X-ray photoemission electron microscope (X-PEEM) and in a scanning transmission X-ray microscope (STXM) have been measured quantitatively using synchrotron radiation. As part of the method of dose evaluation in X-PEEM, the characteristic (1/e) sampling depth of X-PEEM for polystyrene in the C 1s region was measured to be 4 ± 1 nm. Critical doses for chemical change as monitored by changes in the X-ray absorption spectra are 80 (12), 280 (40) and 1230 (180) MGy (1 MGy = 6.242*ρ eV/nm3, where ρ is the polymer density in g/cm3) at 300 eV photon energy for PMMA, Fg and PS, respectively. The critical dose for each material is comparable in X-PEEM and STXM and the values cited are thus the mean of the values determined by X-PEEM and STXM. C 1s, N 1s and O 1s spectroscopy of the damaged materials is used to gain insight into the chemical changes that soft X-rays induce in these materials. |
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Keywords: | Radiation damage Soft X-rays Photoemission electron microscopy Scanning transmission X-ray microscopy Polystyrene Poly(methyl methacrylate) Fibrinogen Polymer thin films |
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