Monitoring surface molecular order in discotic liquid crystals

Polarized confocal Raman spectroscopy is used to monitor surface molecular alignment in a droplet of a prototype discotic liquid crystal. We show that polarization selection rules of Raman active modes can be used to infer molecular alignment along specific directions in situations where no other experimental technique is available. Substrate-induced planar alignment along the wetting edge of a droplet, as well as molecular orientation around topological surface defects are explicitly shown.