This article describes how to establish the full structure of samples in SAXS/WAXS experiments without altering the sample-to-detector distance.
Prior to performing a new SAXS/WAXS experiment to determine the structure of an unknown sample, it is good practice to obtain data about its properties such that the study can focus on the q-ranges of interest. Obtaining this background information on a sample, from either the complementary methods or literature, can be tedious and is sometimes not possible.
The Discovery Mode with Pilatus3 R 1M combined with a SWAXS module can cover a large, continuous q-range from 0.037 to up to 30.53 nm
-1. This unique ability allows researchers to identify relevant domains to do sample screening. The angular coverage is realized through a single measurement, which saves valuable time that is otherwise spent on detector motion along the beam axis.
Measurements and Results
A sample of block copolymer was studied with a SAXS/WAXS acquisition by using the Xeuss 2.0 SAXS/WAXS system. This experimental set-up integrates two types of DECTRIS detectors: a PILATUS3 R 1M detector and a proprietary hybrid pixel SWAXS module.
The SAXS sample-to-detector distance d
SD SAXS is equivalent to 569 mm. A 10 minute exposure time was performed and the 2D patterns acquired are depicted in Figure 1.
Figure 1. 2D SAXS (left - PILATUS3 R 1M detector) and WAXS (right - SWAXS module) patterns from a block copolymer sample obtained at d SD SAXS = 569 mm. Exposure time = 10 min. Axis unit = q [nm -1].
The matching scattering curve is shown in Figure 2, revealing the characteristic peaks in intensity across a large q-range (Table 1).
Figure 2. Scattering curve from a block copolymer sample resulting from simultaneous SAXS/WAXS measurement at d SD SAXS = 569 mm. Exposure time = 10 min.
Table 1. q-range and corresponding 2θ range. The Discovery Mode of the Xeuss 2.0 provides structural information about unknown samples nearly 3 decades in q (typical d_spacing [0.2 - 170] nm) with a single measurement.
-1] 2θ [°]
Such data allows simultaneous determination of a sample’s structures from the nanoscale to the crystalline scale. The scattered intensity covers over 5 magnitudes; emphasizing the capability to locate both strong and weak scattering signals.
If needed, a certain q-range of interest can be defined for further studies. A better angular resolution and flux/q-min compromise can be achieved if measurements are carried out at a longer sample-to-detector distance, while a larger azimuthal angle of detection can be realized if measurements are performed at a shorter detector distance.
To Go Further
The continuous extended data collection area of the
Discovery Mode allows the exploration of a large number of samples. This high sampling volume considerably enhances the throughput of the Xeuss 2.0 SAXS/WAXS system.
To cite a few examples, the Discovery Mode also helps when comparing different types of processing conditions, exposing a completely disordered state or establishing structural organizations at different length scales.
Besides, on-site multi-scale dynamic analyzes and phase transitions studies can be carried out as a function of magnetic or electric fields, temperature and stretching forces.
This information has been sourced, reviewed and adapted from materials provided by Xenocs.
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