A prototype sample cell has been designed and tested with the long-term aim of following heterogeneous catalysischemistry and aerosol synthesis on optically trapped aerosols at temperatures approaching 500 °C. Liquid aerosol dropletsthat contain high molecular weight molecules that gel, and then solidify, at higher temperatures have become of increasinginterest to the catalysis community. To address the challenges of performing spectroscopic studies on individual airborneparticles at high temperatures a sample cell was designed to localise heating at the optical trapping position whilstmaintaining the objective lenses at close to ambient temperature. The heating cell was tested using polystyrene beads (2.0μm diameter) that were trapped in air between opposed 1064 nm laser beams, and illuminated with a broadband whiteLED. Backscattered light from the trapped particle was collected to obtain a Mie spectrum over the 450-620 nm wavelengthrange. Mie spectral fitting was used to determine particle radius and wavelength dependent refractive index. In addition, a514.5 nm laser beam was used to illuminate the particle to generate a Raman spectral signal. Raman spectroscopy enablesthe measurement of conformational changes in the polymer sample. The trapped particle was heated within the aperture ofa ceramic heating element and retained through the melting point of polystyrene (～240 °C). The changes in size andrefractive index were measured. Both the glass transition temperature (Tg), melting point and the thermal expansioncoefficient of a single bead were determined in comparison to literature values.
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