X-Ray Scattering to Determine Complete Sample Structure

Table of Contents

Introduction
Measurements and Results
Conclusion

Introduction

Prior to performing Small Angle and Wide Angle X-Ray Scattering (SAXS/WAXS) experiments, it is recommended to gather total information about the characteristics of an unknown sample from either complementary techniques or available literature.

Aided by the background information, it is possible to determine the appropriate q-range for the study. However, it may not always be possible for researchers to attain the relevant information.

Certain cases may need a rapid investigation of a sample from the nanoscale level to the crystalline scale. Covering a continuous and large q-range starting from 0.037 up to 30.53 nm-1 and the identification of corresponding domains are possible using Discovery Mode.

The sample can be screened because angular measurements like this can be accomplished in a single measurement, preventing the wasting of time due to detector motion along the beam axis.

Measurements and Results

A Xeuss 2.0 SAXS/WAXS system was used to examine a block copolymer sample through a parallel SAXS and WAXS acquisition. Two DECTRIS detectors were incorporated for the experiment: a proprietary hybrid pixel SWAXS module and a PILATUS3 R 1M detector. The distance between the detector and sample in the SAXS investigation (dSD SAXS) and the exposure time were 569 mm and 10 minutes respectively.

Figure 1 shows the corresponding 2D patterns that were obtained.

2D SAXS and WAXS patterns

Figure 1. 2D SAXS (left - PILATUS3 R 1M detector) and WAXS (right - SWAXS module) patterns from a block copolymer sample obtained at dSD SAXS = 569 mm. Exposure time = 10 min. Axis unit = q [nm-1].

Figure 2 represents the corresponding scattering curve in which many areas of interest across a wide q-range are shown (Table 1). The nanoscale and crystalline level measurements of the structures can be obtained concurrently based on these areas.

Scattering curve from a block copolymer sample

Figure 2. Scattering curve from a block copolymer sample resulting from simultaneous SAXS/WAXS measurement at dSD 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.

q [nm-1] 2θ [°]
min 0.037 0.052
max 30.53 44.00

The results show that the scattered intensity is spread across five magnitudes which emphasize the capability of detecting both weak and strong scattering signals. If necessary, a q-range of interest can be defined and studied additionally.

By performing measurements over a longer sample-to-detector distance, better angular resolution and flux/q-min compromise can be attained, while on the other hand, measurements over a shorter distance cover a larger azimuthal angle of detection.

Conclusion

The Discovery Mode offers a continuous extended data collection area, which is ample for the examination of most of the samples and optimizing the throughput of the Xeuss 2.0.

A few examples include revealing a completely disordered state, determining the structural organization at different length scales or the comparison of different processing conditions. Phase transitions and onsite multi-scale dynamic studies can be conducted as a function of stretching forces, electric or magnetic fields, and temperature.

Xenocs

This information has been sourced, reviewed and adapted from materials provided by Xenocs.

For more information on this source, please visit Xenocs.

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