84. The quenching of the fluorescence of anthracene

Kinetic Study of the External Heavy-Atom Quenching of Fluorescence in Liquid Solution under High Pressure

“…This phenomenon is attributed to increased intersystem crossing induced by the interactions between the fluorophore and heavy-atom quencher molecules in deactivation . The quenching rate constant, k q , varies from diffusion controlled to kinetically controlled depending on the heavy-atom quencher. − The fact that k q changes in a wide range has been interpreted by assuming an exciplex, (MQ)*, that is formed reversibly between the fluorophore ( 1 M*) and heavy-atom quencher (Q) molecules, although no emission characteristics of an exciplex have been observed. − For strong quenchers, such as carbon tetrabromide, the quenching is nearly diffusion controlled as a result of the faster deactivation of (MQ)* compared with the dissociation. − ,, For weak quenchers, such as carbon tetrachloride, on the other hand, the dissociation is much faster than deactivation so the quenching is less than the diffusion rate. ,− …”

“…1 The quenching rate constant, k q , varies from diffusion controlled to kinetically controlled depending on the heavy-atom quencher. [2][3][4][5][6][7][8][9] The fact that k q changes in a wide range has been interpreted by assuming an exciplex, (MQ)*, that is formed reversibly between the fluorophore ( 1 M*) and heavy-atom quencher (Q) molecules, although no emission characteristics of an exciplex have been observed. [2][3][4][5][6][7] For strong quenchers, such as carbon tetrabromide, the quenching is nearly diffusion controlled as a result of the faster deactivation of (MQ)* compared with the dissociation.…”

“…[2][3][4][5][6][7][8][9] The fact that k q changes in a wide range has been interpreted by assuming an exciplex, (MQ)*, that is formed reversibly between the fluorophore ( 1 M*) and heavy-atom quencher (Q) molecules, although no emission characteristics of an exciplex have been observed. [2][3][4][5][6][7] For strong quenchers, such as carbon tetrabromide, the quenching is nearly diffusion controlled as a result of the faster deactivation of (MQ)* compared with the dissociation. [2][3][4][5][6]8,9 For weak quenchers, such as carbon tetrachloride, on the other hand, the dissociation is much faster than deactivation so the quenching is less than the diffusion rate.…”

“…[2][3][4][5][6][7] For strong quenchers, such as carbon tetrabromide, the quenching is nearly diffusion controlled as a result of the faster deactivation of (MQ)* compared with the dissociation. [2][3][4][5][6]8,9 For weak quenchers, such as carbon tetrachloride, on the other hand, the dissociation is much faster than deactivation so the quenching is less than the diffusion rate. 2,[4][5][6][7] A few high-pressure studies on the fluorescence quenching by some heavy-atom quenchers have been reported.…”

“…[2][3][4][5][6]8,9 For weak quenchers, such as carbon tetrachloride, on the other hand, the dissociation is much faster than deactivation so the quenching is less than the diffusion rate. 2,[4][5][6][7] A few high-pressure studies on the fluorescence quenching by some heavy-atom quenchers have been reported. [10][11][12][13] Recent work 13 revealed that the rate constant, k q , for the fluorescence quenching by carbon tetrabromide of pyrene and 1,2-benzanthracene decreases significantly with increasing pressure at pressures up to 400 MPa.…”