Chemistry III Electronic Spectra

It is not always possible to make a simple prediction of color directly from the absorption spectrum, in large part because many coordination compounds contain two or more absorption bands of different energies and intensities. The net color observed is the color predominating after the various absorptions are removed from white light. 

For reference, the approximate wavelengths and complementary colors to the principal colors of the visible spectrum are given in Table 11-1. 

FIGURE 11-1 Absorption Spectrum of [Cu(H20)6] -(Reproduced with permis.sion from B. N. Figgis, Introduction to Ligand Fields, Wiley-Interscience, New York, 1966, p. 221.) 

The Beer-Lambert law may be used to describe the absorption of light (ignoring scattering and reflection of light from cell surfaces) at a given wavelength by an absorbing species in solution  

I = path length through solution (cm) c = concentration of absorbing species (mol L ) 

---