Wavelength and energy units

The position of an absorption band is measured on a wavelength scale which may be calibrated in angstroms (A), nanometre (nm) or micron (pm) units. Angstrom units were most commonly used in early mineral spectroscopy literature, including the first edition of this book. However, in current spectral mineralogy research, absorption spectra are often plotted on nanometre scales, whereas micron units are commonly employed in reflectance spectra and remote-sensing applications (chapter 10). The relationship between these wavelength units is 

Some spectra are recorded on a wavenumber scale, which is inversely proportional to wavelength. The most common wavenumber unit is the reciprocal centimetre, which is related to wavelength units as follows  

The advantage of the wavenumber scale is that it is linearly proportional to other energy units. Some of the relationships and conversion factors (see Appendix 8) are as follows  

3 Energy level diagrams and crystal field spectra 

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Table 1.1 Equivalence oiirequency. wavelength and energy units for electromagnetic radiation...

Table 3.1. Wavelength and energy units used in crystal field spectra...

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