The Fundamentals of Spectral Analysis

The slit in the so-called collimator is depicted as a line on the photographic plate or film, different Hnes for different wavelengths. Nowadays special plates, CCD-plates, are used in order to avoid the need to develop photographic plates. In these, the surface is covered with square picture elements, the number of which per surface unit is expressed as pixels of the CCD unit. 

The positions of the lines and the combination of lines are a fingerprint of the actual element. 

The spectroscopic method was used in looking for the RE and other elements. It gave clarity but also confusion. The spectra of heavy metals in the visible and ultraviolet regions are very rich in hnes as a consequence of the fact that every wavelength (Hne) corresponds to a transition between two energy levels in the outer electronic shell of the atom. A heavy metal atom is very complex and has many possible electron transitions. The lines from an unknown element were impossible to predict and could not be known until the element was discovered, which was the reason for con- 

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