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Triboemission – i.e. the emission of photons, electrons and other charged particles that arise from a sliding contact – may play a key role in tribochemical processes, such as lubricant degradation. However, the mechanisms that give rise to this type of emission are not well understood. For the first time, we present spatially resolved measurements of electron emission, obtained as a range materials are worn. These are obtained from scratch tests, carried out under vacuum conditions (10−5 Torr), in which microchannel plates coupled to a phosphor screen are used to image electron emission. The results show that electron emission occurs at specific locations on the worn surface and, depending on the conductivity of the material, these sites remain active and decay with a time constant of up to several seconds. SEM images of the worn surface at these sites reveal that either surface fractures or grain defects are present. This suggests that fractoemission mechanisms are at least partially responsible for triboemission (however, the possible contribution of tribocharging mechanisms are also discussed). Specifically, this provides evidence to support the theory that triboemission results from the imbalance of charge on opposing faces of wear cracks and that this generates an electric field sufficient to accelerate molecular fracture products, which then bombard the surface leading to secondary emission. The strong geometric correlation between damage topography and electron emission distributions shows the potential of using this technique to monitoring wear and crack formation in real time and under high (30x) magnification.

Line-chain carbon films are a promising broadband material for use in devices; therefore, a deep understanding of the surface electronic structure is important. The Kelvin Probe (KP), Surface Photovoltage / Surface Photovoltage Technology (SPV / SPS), and Am-bient Air Emission Spectroscopy (APS) techniques are typically applied to conventional and organic semiconductor materials. In this study, measurements using a combination of KP, SPV / SPS, and APS methods take samples of linear-chain carbon films on copper and curved substrates to study their surface electronic structure and compare their various properties. These methods are non-contact and non-destructive. It was found that the position of the Fermi level of the samples does not change (4.83 ± 0.01 eV). The measured samples showed a good response to photoemission. Thus, the KP, SPV / SPS and APS measurement methods provided some interesting information about samples of linear-chain carbon films and an in-itial study of their surface electron states.

The Kelvin probe is a non-contact, non-destructive vibrating capacitor device that measures the work function difference between a conducting sample and a vibrating tip. This contribution focuses on inline monitoring of the surface (photo)voltage of deposited silicon layers. We apply a custom-built in situ Kelvin probe, operated in a roll-to-roll PECVD system, located immediately after the plasma zones to enable direct feedback to the controlling system of the plasma deposition. The surface photovoltage of nip thin film Si solar cells increases with increasing V oc . The results imply that inline, contactless measurements of the open-circuit voltage are possible and that thus monitoring the doped layer quality during roll-to-roll production is feasible.