UV-VIS spectroscopy is one of the oldest methods in molecular spectroscopy. The definitive formulation of the Bouguer-Lambert- Beer law in 1852 created the basis for the quantitative evaluation of absorption measurements at an early date. This led firstly to colorimetry, then to photometry and finally to spectrophotometry. This evolution ran parallel with the development of detectors for measuring light intensities, i.e. from the human eye via the photo- element and photocell, to the photomultiplier and from the photo- graphic plate to the present silicon-diode detector both of which allow...