International audienceCleaning in an aqueous solution is a complex mechanism which depends on several parameters. The quartz crystal microbalance (QCM) technique was used to investigate the detachment, using an anionic and a nonionic detergents, of stearic acid (C18H36O2) films deposited on gold-coated quartz surfaces. The cleaning mechanism was observed in real time by measuring the frequency of a quartz crystal during the fatty acid film removal. These observations reveal two successive phenomena: firstly, adsorption and absorption of water and detergent on the stearic acid layer and, secondly, the detachment of the fatty acid layer. A relationship between removal time and detergent concentration was highlighted: fatty acid removal time decreases as detergent concentration increases until an asymptotic value is reached. Initial contamination greatly influences cleaning duration. Increased sample contamination actually leads to increased removal time. However, no real correlation between the two parameters can be established. As a result, optimal parameters can be determined for each detergent, thus the QCM technique appears to be of great interest in monitoring and optimising cleaning protocol

International audienceOrganic contamination may decrease the targeted performances of coated surfaces. To study the contamination induced by surrounding materials, a method using a thermal extractor is presented in the first part of this work. Besides its normal operation (analyses of outgassing compounds from a material), this device is used in an original way to contaminate and decontaminate samples. Efficiency of contamination and decontamination protocols are assessed by automated thermal desorption and gas chromatography coupled with mass spectrometry and by secondary ion mass spectrometry coupled with a time of flight mass analyzer. This enables to study the contamination induced by a bulk material outgassing and to take in consideration the possible competition between outgassed species. This method is then applied to investigate contamination of Laser MégaJoule sol–gel coated optics by a retractable sheath. The impact of the temperature on the outgassing of the sheath has been highlighted. Increasing temperature from 30 to 50 • C enables the outgassing of organophosphorous compounds and increases the outgassing of oxy-genated compounds and phthalates. Chemical analyses of contaminated optics have highlighted affinities between the sol–gel coating and phthalates and organophosphorous, and low affinities with aromatics and terpens. Finally, samples with increasing levels of contamination have been realized. However a saturation phenomenon is observed at 90 ng cm–2

No abstract

No abstract