Figure 10. Absorption spectrum of the aqueous dye solutions (blue line: dyes from the Herlitz pen, red line: aqueous solution of brilliant yellow and brilliant blue FCF)

From

Color-Changing Markers – An Exiting Topic for Inquiry-Based Chemistry Education

M. Ducci

World Journal of Chemical Education. 2018, 6(1), 24-28 doi:10.12691/wjce-6-1-5