Various types of contaminants present during fabrication, storage, and transport processes may have a significant negative impact on materials and devices used in space. Similar difficulties may apply to the aerospace or other industries. Therefore, monitoring the level of contamination is an important factor in the production process. In the case of organic pollutants, infrared spectroscopy is used as a quick and convenient analytical method.

European Space Agency (ESA) requests a Cleanliness and Contamination Control Plan (C&CCP) including Molecular Organic Contamination (MOC). The currently applicable ECSS-Q-ST-70-05C document describes the preparation of the mentioned calibration standards for FT-IR instrument calibration. Preparation of each sample is typically done by manual deposition of a liquid solution, with the known concentration of a calibration compound. Unfortunately, several issues are associated with this procedure which was confirmed in 2017 during interlaboratory comparison of MOC measurements [1].

For these reasons, ESA commissioned work devoted to the development of a new methodology for calibration standard preparation. During the interlaboratory test, we demonstrated the highly reproducible uniformity of organic films deposited by the spin-coating technique. In this project, we extend the use of spin-coating to a broad range of surface concentrations of calibration species. In our strategy, a mixture of a matrix polymer (deuterated polystyrene) inactive in selected spectrum ranges and small admixtures of IR active species (standards known from ECSS-Q-ST-70-05C) were used. The prepared standard curves based on deposited polymer thin films show good linearity. Importantly, our approach provided also the possibility of determining the amount of Paraffin, MPS, and DOP using an alternative to the IR method – weighing the mass of the layer.

[1]. Malicki, M., et al., Proceedings of the 14th ISMSE&12th ICPMSE, Biarritz, France, 2018 – “Molecular Organic Contamination – FT-IR Measurement Interlaboratory Comparison and Error Analysis”.