Lohse, P. W., Buersing, R., Lenzer, T., & Oum, K. (2008). Exploring 12'-apo-β-carotenoic-12'-acid as an ultrafast polarity probe for ionic liquids. Journal of Physical Chemistry B, 112(10), 3048-3057. Retrieved from http://pubs.acs.org/cgi-bin/article.cgi/jpcbfk/2008/112/i10/pdf/jp710766z.pdf.