Alkanes as Intelligent Surface Thermometers: A Facile Approach to Characterize Short-Lived Temperature Gradients on the Micrometer Scale

Short-lived micro-sized thermal gradients are challenging to measure. Especially, in thin film processes and devices, it is important to know the exact temperature profile to assure process parameters and the stability of sensitive materials. Many theoretical models try to describe the occurring temperatures, but still lack in profound experimental data. Here, a facile approach is presented, which allows to measure confined temperature gradients with millisecond and micrometer precision. By casting a thin alkane film onto a substrate of interest, it is possible to reconstruct local temperature gradients by imaging the phase behavior and morphology of the alkane film with a simple optical microscope setup. Alkanes are inert and their melting and boiling temperatures depend on the chain length. This allows to measure temperatures between 37 and 522 degrees C on any surface. Furthermore, after thorough characterization of laser-induced temperature gradients, this approach can be used to measure the phase transition behavior of complex thin film polymer mixtures.