TABLE OF CONTENTS It is commonly stated that there are fifteen specific causes of colour, arising from a variety of physical and chemical mechanisms. These mechanisms may be collected into five groups.
Colour from simple excitations: colour from gas excitation ( e.g. vapour lamps, neon signs), and colour from vibrations and rotations ( e.g. ice, halogens);
colour from ligand field effects: colour from transition metal compounds and from transition metal impurities;
colour from molecular orbitals: colour from organic compounds and from charge transfer;
colour from band theory: colour in metals, in semiconductors, in doped semiconductors and from colour centres;
colour from geometrical and physical optics: colour from dispersion, scattering, interference and diffraction.
This book is focused on the industrially important organic dyes and pigments and, to a certain extent, inorganic pigments and thus deals almost exclusively with colour generated by the mechanisms described by group (c).
