Optical trapping and spectroscopic characterisation of ionic liquid solutions

Abstract

This paper presents a study of the optical trapping of aerosols containing ionic liquid (IL). Droplets comprised of aqueous solutions of the IL ethylammonium nitrate (EAN) are demonstrated to be readily trapped by optical tweezers and are characterized spectroscopically, by analysing the morphology dependent resonances present within backscattered light originating from a broadband light emitting diode. The response of the droplets to conditions of varying relative humidity has also been investigated, as an important first step in measuring the uptake of gases by ILs. Finally, a comparison between broadband Mie scattering and cavity enhanced Raman spectroscopies is provided.