Oxygen-Varying Correlated Fluorescence for Determining the Stern–Volmer Constant of Porphyrin
Meng Kou, Feng Qin, Weiming Lv, Xiyu Zhang, Yongda Wang, Hua Zhao, Zhiguo Zhang
Abstract
The achievement of the Stern–Volmer constant (KSV) of porphyrin, a parameter to describe the ability of energy transfer to oxygen, enables us to understand and engineer the functionalities of porphyrin. In this study, we propose a new method to obtain KSV by steady fluorescence based on the population correlation between the excited triplet state (T1) and the singlet excited state (S1). Nonlinear fluorescence intensity of porphyrin [hematoporphyrin monomethyl ether (HMME)] as a function of pump power is observed, and this nonlinearity is oxygen-concentration-dependent. These observations originated from the population correlation, where more intense pump power introduces a stronger population correlation. Most importantly, we have found that the oxygen content can influence this correlation via the quenching of T1 based on its sequent change of fluorescence intensity; KSV ∼ 28 kPa–1 can be obtained theoretically for HMME. Our investigation not only offers a promising method of achieving KSV conveniently by steady fluorescence but also enlightens the advances of regulable fluorescence correlation.