Eur. Phys. J. Special Topics 167, 113-119 (2009)
https://doi.org/10.1140/epjst/e2009-00945-4

A simultaneous multiwavelength dispersive X-ray reflectometer for time-resolved reflectometry

¹ Photon Factory, Institute of Materials Structure Science, High Energy Accelerator Research Organization, Tsukuba, Ibaraki, Japan
² Department of Physics, Tokyo Gakugei University, Koganei, Tokyo, Japan
³ Center for Advanced Microscopy and Spectroscopy, IMRAM, Tohoku University, Katahira, Aoba-ku, Sendai, Japan
⁴ Engineering Center, High Energy Accelerator Research Organization, Tsukuba, Ibaraki, Japan
⁵ National Institute for Materials Science, Tsukuba, Ibaraki, Japan

Corresponding author: tadashi.matsushita@kek.jp

Abstract

Aiming for the realization of time-resolved specular X-ray reflectivity measurements on the sub-second to millisecond timescales, a conceptually new method of measuring specular X-ray reflectivity curves is developed. Using this method the entire profile of the reflectivity curve of interest is measured in place. A horizontally convergent X-ray beam which has a one-to-one correlation between its direction and energy is realized using a curved crystal or laterally graded multilayers on an elliptic substrate. The X-ray beam is then incident on the surface of the specimen placed at the focus such that the glancing angle in the vertical direction is the same for all X-ray components, which are reflected in the vertical direction by the surface and diverge in the horizontal plane. The perpendicular momentum transfer continuously changes as a function of the horizontal ray direction even with fixed glancing angle since the wavelength (energy) changes. The X-ray intensity distribution across the beam direction measured downstream of the specimen using a one- or two-dimensional detector represents the X-ray reflectivity curve. Specular X-ray reflectivity curves are measured with exposure times ranging from 2 ms to 1 s for a gold film of thickness 14.3 nm on a silicon substrate. The potential of this method for time-resolved measurements is demonstrated by recording reflectivity curves with a time resolution of 20 ms from a rotating specimen.