Some chemical reactions are induced by light and are called photochemical reactions. The absorption of light delivers the energy needed to start the reaction. At IMO, high energy UV light is used to functionalize different carbon surfaces like diamond and carbon nanowalls (a form of few layer graphene). Hereby, an unsaturated fatty acid linker molecule is covalently bound to the surface of the carbon material. This is done by irradiating the fatty acid covered surface with UV light for 20 hours.
The used UV light has an intensity peak at a wavelength of 254 nm and delivers an on sample power of 265 mW/cm2. The UV lamp (TUV G4T4 4W lamp, Philips) is mounted in an EPROM eraser box (ME5, Lawtronics) that allows samples with a maximum size of 15 cm x 6 cm. The reaction is performed in an inert nitrogen atmosphere to prevent ozone formation.
The functional group of the linker molecule can subsequently be used to attach a molecule of interest to this linker.