The development of a Microsoft® Excel® spreadsheet is described, for the accurate
calculation of CIE (Commission Internationale de l’Eclairage) 1931 xy chromaticity
coordinates and luminance data from visible region absorption spectra recorded in
transmission mode. Using firmly established CIE principles, absorbance-wavelength data
from visible spectra are taken as input, with chromaticity coordinates being generated as
output. Colour stimulus measurement example calculation results are firstly presented for
aqueous solutions of the dyes, Erythrosin B (red, x, y = 0.608, 0.365), Acid Green 25 (x, y
= 0.086, 0.298) and Remaxol Brilliant Blue R (x, y = 0.153, 0.045), and then for tracking
electrochromic in situ colour stimulus changes in the methyl viologen and di-n-heptyl
viologen systems. The quantification of colour during each viologen dication to cationradical
reduction process, and each reverse (oxidation) process, showed that subtle changes
in both hue and luminance could be detected, with evidence of colour contributions from
both the cation radical and the cation radical dimer.
Ruthenium purple (RP) films on transmissive tin-doped indium oxide (ITO)/glass
substrates have been synthesised by a novel electrochemical coagulation technique. Using
the CIE system of colorimetry, the colour stimulus of the electrochromic RP films and the
changes that take place on reversibly switching to the colourless form have been calculated
from in situ visible spectra recorded under electrochemical control. (Continues...)
