The effects of ultraviolet-B (UV-B) radiation on photosystem II (PS II) were studied in leaves of Chenopodium album. After the treatment with UV-B the damage was estimated using chlorophyll a fluorescence techniques. Measurements of modulated fluorescence using a pulse amplitude modulated fluorometer revealed that the efficiency of photosystem II decreased both with increasing time of UV-B radiation and with increasing intensity of the UV-B. Fluorescence induction rise curves were analyzed using a mechanistic model of energy trapping. It appears that the damage by UV-B radiation occurs first at the acceptor side of photosystem II, and only later at the donor side.
van Rensen, J. J. S., Vredenberg, W. J., & Rodrigues, G. C. (2007). Time sequence of the damage to the acceptor and donor sides of photosystem II by UV-B radiation as evaluated by chlorophyll a fluorescence. Photosynthesis Research, 94(2), 291-297. https://doi.org/10.1007/s11120-007-9177-x