Radiation damage in soft X-ray microscopy

• Published in: Journal of electron spectroscopy and related phenomena 2009-03, Vol.170 (1), p.25-36
• Main Authors: Wang, J., Morin, C., Li, L., Hitchcock, A.P., Scholl, A., Doran, A.
• Format: Article
• Language: English
• Subjects: Fibrinogen; Photoemission electron microscopy; Poly(methyl methacrylate); Polymer thin films; Polystyrene; Radiation damage; Scanning transmission X-ray microscopy; Soft X-rays
• ISSN: 0368-2048; 1873-2526
• DOI: 10.1016/j.elspec.2008.01.002

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/nm 3, where ρ is the polymer density in g/cm 3) 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.