For centuries indigo has been used as both a dye for textiles and as a pigment in paints. The prominent color of indigo is blue, but under magnification other colors are also present. Earlier studies1 have used micro-Raman spectroscopy to distinguish between synthetic and natural indigo. The aim of this work is to first establish a clear Raman signal for distinguishing between different colors of indigo and then use it to better understand the cause and conditions creating color changes.
1. Peter Vandenabeele and Luc Moens. Analyst, 2003, 128, 187-193.