Thin film materials are used on liquid and powder sample cups to assist the samples while enabling the transmission of X-Rays into the sample and back to the detector.
It is crucial that the material supporting the window is see-through for all signals produced by the analytes of interest and that it is chemically suitable for the samples.
Various window materials are currently available in many different thicknesses for sample containment, including Kapton, Polypropylene, and Mylar®. These materials can be provided as perforated rolls of film, pre-cut circles, or continuous rolls.
XRF Film Materials
Kapton
Kapton is a resilient polyamide with an orange/yellow hue, known for its stability over a broad temperature range and typically having a thickness of 7.5 µm. While Kapton can accommodate most samples, it is notably sensitive to strong basic solutions. For ASTM methods assessing sulfur in diesel, Etnom® or Kapton is exclusively specified.
Polypropylene
Polypropylene is a thin plastic film with significant %-transmittance for both light and heavy elements, even at low concentrations, with a usual thickness of 6 or 12 µm.
This slightly thicker film offers added protection against tearing. Despite having better transmission than Mylar® film, polypropylene exhibits a lower tensile strength.
Mylar®
Mylar® is suitable for numerous routine XRF analyses and is commonly employed for sulfur detection in oils, fuels, and lubricants (excluding diesel, as mentioned earlier).
It is also tough with a high tensile strength that resists tearing from liquid samples. However, a drawback of Mylar® is its lack of chemical compatibility with aliphatic alcohols, esters, ketones, or aromatics.
Features
- Self-adhesive protective films
- Pre-perforated rolls available
- Continuous rolls available
- Pre-cut circles available
- A wide range of materials and sizes are available