Quick X-ray reflectivity using monochromatic synchrotron radiation for time-resolved applications

Abstract

We describe and demonstrate a new technique for parallel collection of x-ray reflectivity data, compatible with monochromatic synchrotron radiation and flat substrates, and apply it to the in-situ observation of thin-film growth. The method employs a polycapillary x-ray optic to produce a converging fan of radiation, incident onto a sample surface, and an area detector to simultaneously collect the XRR signal over an angular range matching that of the incident fan. Factors determining the range and instrumental resolution of the technique in reciprocal space, in addition to the signalto-background ratio, are described in detail. Our particular implementation records is the first method that is both sample-independent and compatible with the highly collimated, monochromatic radiation typical of 3rd generation synchrotron sources.Further, our technique can be readily adapted for use with laboratory-based sources.

Recent developments in the application of X-ray and neutron reflectivity to soft-matter systems

“…Another method, which is similar to divergent beam methods for NR, as described in the next section, is presented by Joress et al [23]. It is based on a polycapillary X-ray optic to produce a converging fan of radiation, the reflection of which is captured by an area detector to simultaneously collect the [23], illustrating the regions of reciprocal space probed by three particular pixels on the detector, the diffraction geometry, and its effect on the resolution. The probed regions for each of three pixels are shown in red, green and blue.…”

Fast fitting of reflectivity data of growing thin films using neural networks

“…In the last years, a range of fast XRR techniques have been developed that can acquire XRR curves on timescales as low as 100 ms (Joress et al, 2018;Lippmann et al, 2016;Mocuta et al, 2018), posing challenges to the data handling if on-line monitoring is required. Some of these methods employ energy-dispersive measurements (Kowarik et al, 2007;Metzger et al, 1994;Mukherjee et al, 2002), which are also used in neutron reflectometry (Cubitt et al, 2018).…”

X-ray reflecto-interferometer based on compound refractive lenses

“…X-ray reflectivity with a convergent polychromatic X-ray beam (Matsushita et al, 2013) was realized on a synchrotron but the approach we proposed with a monochromatic beam solves the problem of changing the refractive index with the wavelength. Most recently, quick X-ray reflectivity (XRR) for thin-film growth was demonstrated using polycapillary optics to produce a converging beam (Joress et al, 2018). However, this approach has poor spatial resolution, requirements to the sample are the same as in the classical XRR, and energy tunability is lacking.…”