Publications: #81

81. "Thickness and Interfacial Roughness Changes in Polymer Thin Films during X-Irradiation" Richter, A.G.; Guico, R.; Shull, K.; Wang, J., Macromolecules, 39, 1545 (2006).

Despite the obvious occurrence of synchrotron X-ray damage to org. thin films, few attempts have been made to qual. det. changes to their structural parameters during X-ray exposure. We report here the use of X-ray reflectivity to study X-radiation damage to thin films of poly(tert-Bu acrylate) and polystyrene at various incident flux densities and sample temps. At the flux densities studied, (0.4-6.7) * 109 photons/(s mm2), the polyacrylate film thickness decreased during irradn. at rates ranging from -0.1 to -4 .ANG./min, while the surface roughness increased. The vol. of polymer removed per incident photon ranged from 150 to 1400 .ANG.3/photon. The rate of the thickness decay of the films was found to be linear with flux d. over the range studied. The damage rate also appears to be directly related to the amt. of X-ray energy deposited in the film, not the amt. of energy available for creation of secondary electrons at the substrate. At comparable flux densities, polystyrene films heated above the glass transition temp. were found to behave similarly to the polyacrylate films, losing between 40 and 250 .ANG.3/photon; however, at room temp. polystyrene films instead slightly increased in thickness.

Journal Link (full text access)