Photoconductivity of Carotenoids

Abstract

Abstract Further studies have been made of the photoconductivity of single crystals of all-trans β-carotene. Photoconductivity spectra have also been determined for the related molecules 15–15′ cis β-carotene, lycopene, β-apo-8′-carotenal, β-apo-8′ -apocarotenoic acid ethyl ester and canthaxanthin, as well as a β-carotene glass. The results strongly indicate that a photoconductivity band which occurs well below the absorption edge in these materials is an intrinsic property of this type of molecule. The UV photoconductivity spectrum of 15–15′ cis β-carotene throws some doubt on previous theories concerning the production of free carriers in β-carotene following illumination by strongly absorbed light.