The everyday XRD instrument that can provide specialized nanoparticle analysis

The common XRD instrument that can provide specialized SAXS quantum dot analysis

Colloidal nanoparticles and quantum dots can be found in a wide range of applications. For example, in solar cells, LEDs, medical imaging, and spin coating. From power generation to optics, there are few fields where quantum dots aren’t a source of excitement. As a result, many research projects could benefit from analyzing these nanostructures – but the cost of the necessary instrumentation can be prohibitive. What if, instead, you could use an instrument that’s common in labs across the world?

Malvern Panalytical has developed techniques to enable its Empyrean X-ray diffraction (XRD) instrument to perform Small-Angle X-ray Scattering (SAXS) analysis in colloidal liquids, and grazing incidence SAXS (GISAXS) on solids. In this way, you can see whether the information obtained opens up exciting possibilities for a research project without having to fully invest in a dedicated SAXS instrument.

What can nanoparticle and quantum dot analysis by XRD and SAXS achieve?

The two key characteristics of nanoparticles such as quantum dots are their internal crystal lattice size and their external particle size. These strongly affect their properties, such as their electrical conductivity or the color they’ll display in a light-emitting diode (LED). The exterior analysis requires measurements in the nanometer range, but interior analysis measurements go into the sub-nanometer (angstrom) range.

In XRD analysis, X-rays are directed toward a nanomaterial sample. When the rays encounter material,  a diffraction pattern created from the interference of scattered rays can be detected and analyzed. The angular intensity of the diffraction pattern varies according to the chemistry and structure of the scattering material. The  diffraction pattern can be used to discern the composition and heterogeneity of the  nanoparticles. Classic XRD typically analyzes structural features in the angstrom range (0.01 – 1 nm).

SAXS (and GISAXS) follow the same principle, but measurements are made at very small scattering angles, typically in the range of 0.1 degrees to 5 degrees. A SAXS signal is observed whenever a material contains structural features on the larger length scale of nanometers, typically in the range of 1-100 nm.

Rather than requiring specialized instrumentation to explore the possibility of SAXS analysis in your research, the Empyrean, present in many laboratories worldwide, can perform these measurements with just a few attachments.

How to adapt your Empyrean XRD to perform SAXS analysis

For weakly scattering colloidal nanoparticles the ScatterX78 module, a focusing mirror, and the PIXcel3D detector used in 1D or 2D mode, an evacuated beam path allows the Empyrean to provide SAXS measurements in a matter of minutes. Alternatively, a variety of setups in air can also provide SAXS and GISAXS measurements on more strongly scattering samples.

EasySAXS data analysis software enables numerous analyses. These include measurements of nanoparticle size distribution and surface-to-volume ratio, radius of gyration by Guinier analysis, checking for the presence of aggregates, and determination of the scattering invariant by Porod analysis.

AMASS software is used to analyze GISAXS scattering patterns for quantum and nanoparticle dots in the solid state and on surfaces via extended simulation of the 1D and 2D reflectometry patterns.

With just a few add-ons, the Empyrean can therefore help researchers analyze colloidal nanoparticles and quantum dots to solve tricky issues in their research projects without the expense of a dedicated SAXS or GISAXS instrument. This is just one more example of its role as a versatile academic instrument that can handle anything you throw at it!

Want to learn more about the Empyrean? Head to its product page to explore more, including customer success stories and application notes!