Triboionization: a Novel Ionization Method by Peeling of Cohesive Substances for Mass Spectrometry

A novel ionization/sampling method termed triboionization was developed. Triboionization is an ionization method that only uses cohesive substances, such as food wrap or sticky tape, and does not require an electrode, electric power supply, heat source, light source, radiation, or gas, unlike most other conventional ambient ionization methods. In this study, the sample compound attached to adhesive tape or plastic wrap was quickly peeled off at a distance of approximately 2 cm from the atmospheric interface of a mass spectrometer. All of the five types of food wrap and 13 types of adhesive tape tested successfully ionized caffeine. Nine out of ten model compounds were detected as the corresponding molecular ions in the positive or negative mode by this ionizing contrivance using an oriented polypropylene adhesive tape. The detected molecular ions were typically protonated molecules or sodium adducts in the positive mode or deprotonated molecules in the negative mode. The elemental compositions of the observed ions were confirmed within 5 ppm by high-resolution mass spectrometry. The triboionization phenomenon was considered to depend on physical and electronic events caused by peeling off a cohesive substance. Triboionization is able to provide a compact ion source using only mechanical mechanisms. Additionally, triboionization allows sticky tape to be used as a convenient sampling device for surface analysis.

Multiscale Friction in Lubricant-Surface Systems for High-Performance Transmissions Under Mild Wear

The lubricant-surface system is complex in nature and can significantly affect the frictional performance of high-performance transmission systems. The complexity stems from the coupled mechanical and chemical phenomena that occur at the interfacial tooth conjunctions. A combined analytical and precision experimental approach is presented to analyse the salient parameters of the lubricant-surface system. A multiscale procedure comprising topographical measurement, pin-on-disc tribometry, atomic force microscopy in lateral force mode, X-ray photo-electron spectroscopy and continuum contact mechanics analysis under mixed non-Newtonian thermo-elastohydrodynamics is used to describe the formation of a tribo-film, as well as wear and frictional characteristics of the lubricant-surface system. The contribution of chemisorbed and physisorbed bonded tribo-film on the boundary coefficient of friction is ascertained at different physical scales. Therefore, the paper presents a novel multiscale analysis, promoting improved understanding of the complex interactions between mechanisms of friction, wear and surface chemistry.