在自由电子激光辐照下掠入射镜表面纳米点的生长。

Growth of nano-dots on the grazing-incidence mirror surface under FEL irradiation.

作者信息

Kozhevnikov I V, Buzmakov A V, Siewert F, Tiedtke K, Störmer M, Samoylova L, Sinn H

机构信息

Shubnikov Institute of Crystallography, Russian Academy of Sciences, Leninskiy Prospect 59, Moscow 119333, Russian Federation.

Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Albert Einstein Strasse 15, 12489 Berlin, Germany.

出版信息

J Synchrotron Radiat. 2016 Jan;23(1):78-90. doi: 10.1107/S160057751502202X. Epub 2016 Jan 1.

DOI:10.1107/S160057751502202X

PMID:26698048

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.

摘要

在X射线光学表面观察到一种新现象：在自由电子激光（FEL）FLASH（波长5 - 45 nm，掠入射角3°）照射下，掠入射镜表面出现纳米点（直径40 - 55 nm，高度8 - 13 nm，表面密度9.4个/μm²）。通过模型计算表明，这些纳米点可能是由于入射碳氢化合物分子聚合形成污染层的过程中出现的。模型中纳米点生长的关键因素是入射峰值强度和光束反射角。峰值强度的降低（例如用同步辐射代替FEL光束）以及入射角仅减小1°（从3°降至2°）都可能导致纳米点完全消失。将模型计算结果与两块FLASH镜的表面分析结果进行了比较。