@misc{kozhevnikov_growth_of_2016, author={Kozhevnikov, I.V., Buzmakov, A.V., Siewert, F., Tiedtke, K., Stoermer, M., Samoylova, L., Sinn, H.}, title={Growth of nano-dots on the grazing-incidence mirror surface under FEL irradiation}, year={2016}, howpublished = {journal article}, doi = {https://doi.org/10.1107/S160057751502202X}, abstract = {A new phenomenon on X-ray optics surfaces has been observed: the growth of nano-dots (40-55 nm diameter, 8-13 nm height, 9.4 dots µm-2 surface density) on the grazing-incidence mirror surface under irradiation by the free-electron laser (FEL) FLASH (5-45 nm wavelength, 3° grazing-incidence angle). With a model calculation it is shown that these nano-dots may occur during the growth of a contamination layer due to polymerization of incoming hydrocarbon molecules. The crucial factors responsible for the growth of nano-dots in the model are the incident peak intensity and the reflection angle of the beam. A reduction of the peak intensity (e.g. replacement of the FEL beam by synchrotron radiation) as well as a decrease of the incident angle by just 1° (from 3° to 2°) may result in the total disappearance of the nano-dots. The model calculations are compared with surface analysis of two FLASH mirrors.}, note = {Online available at: \url{https://doi.org/10.1107/S160057751502202X} (DOI). Kozhevnikov, I.; Buzmakov, A.; Siewert, F.; Tiedtke, K.; Stoermer, M.; Samoylova, L.; Sinn, H.: Growth of nano-dots on the grazing-incidence mirror surface under FEL irradiation. Journal of Synchrotron Radiation. 2016. vol. 23, no. 1, 78-90. DOI: 10.1107/S160057751502202X}}