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The spectra of monochromators exhibit a marked multi co-linearity. This means that two wavelengths which are adjacent to one another do, by and large, contain the same information, and one of the wavelengths is therefore superfluous. If the absorption at the wavelength of 1200 nm rises, for example, with the content value of a constant substance, then the absorption values will also rise at the wavelengths of 1202 and 1204 nm. This observation provides an insight with regard to untransformed spectra in view of what has been said previously with regard to particle size effects, but it also applies to transformed spectra.
This property of the spectra takes effect in the determination of the calibration equation, in that the coefficient (b-vector in formula) is afflicted with substantial variants, and are therefore unreliable. Multi co-linearity also means, however, that the information in the spectra is redundant. With fewer wavelengths, it is possible that exactly as much can be described. Spectra can therefore be compressed by means of suitable methods, without information regarding the sample being lost. | |
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