||Kihara S, Hartzler DA, Savikhin S. Oxygen concentration inside a functioning photosynthetic cell. Biophys J. 2014 May 6 106(9):1882-9. doi: 10.1016/j.bpj.2014.03.031 p.1887 left column 2nd paragraphPubMed ID24806920
|| Niedzwiedzki DM, Blankenship RE. Singlet and triplet excited state properties of natural chlorophylls and bacteriochlorophylls. Photosynth Res. 2010 Dec106(3):227-38. doi: 10.1007/s11120-010-9598-9PubMed ID21086044
||Primary source abstract: "Ten naturally occurring chlorophylls (a, b, c (2), d) and bacteriochlorophylls (a, b, c, d, e, g) were purified and studied using the optical spectroscopic techniques of both steady state and time-resolved absorption and fluorescence."
||P.1887 left column 2nd paragraph: "Under air-saturated conditions (C0 = 230 μM), these states are quenched by molecular oxygen with ∼100% quantum efficiency, resulting in the production of significant quantities of singlet oxygen that can destroy the (B)Chls, as well as other cell constituents. [Investigators] define the critical oxygen concentration, Ccrit, as the oxygen level at which the rate of intrinsic triplet-state decay, kint, is equal to the oxygen mediated quenching rate. The intrinsic decay rate of triplet excited states for various (B)Chl molecules at room temperature has been shown to be kint ≈ (400 μs)^−1 (primary source)."