IR and Raman spectroscopy in the study of carotenoids of Cladophora rivularis algae

Using Raman and infrared spectroscopy it has been found that during the normal life of algae (pH changes from 8.0 to 9.0) the content of carotenoids increases and the molecules change their conformation: the contribution of–C=C–bonds of the polyene chain of a carotenoid molecule (Raman spectroscopy) is reduced and the contribution of methyl groups (∼2940 cm–1) and aromatic C–H-plane deformation vibrations (band at 1050 cm–1) of carotenoid molecules (infrared spectroscopy) decreases as well. It is the opinion of the authors that a change in the extracellular pH within the normal range has no influence on the content of chlorophyll a and b, but tends to increase the content and alter the conformation or structure of carotenoid molecules.