Optical Absorption Spectroscopy

Optical absorption spectroscopy is an effective method to investigate the local atomic and electronic structure of minerals. Whereas diffraction methods average a volume of several thousands of Å^3 in a mineral structure, optical spectroscopy may elucidate the structural and electronic properties of local polyhederal centers and thus forms a valuable addition to the diffraction methods. Optical absorption spectra of minerals result from the interaction with electromagnetic radiation in the energy range of 40 000 cm^(-1) to 4000 cm^(-1) corresponding to the wavelength range of 250 nm to 2500 nm. Recent reviews of this field have been presented (Burns 1970; Platonov 1976; Marfunin 1979; Nassau 1983; Langer 1984, 1988; Berry and Vaughan, 1985; Rossman 1988; and Vaughan 1990)