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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Fluorescence Quenching by Oxygen of 9,10-Dimetylanthracene in Liquid and Supercritical Carbon Dioxide
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Fluorescence Quenching by Oxygen of 9,10-Dimetylanthracene in Liquid and Supercritical Carbon Dioxide

机译：液态和超临界二氧化碳中氧气对9,10-二甲基蒽的荧光猝灭

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摘要

The contribution of diffusion to the fluorescence quenching by oxygen of 9, 10-dimethylanthracene (DMEA) in liquid C0_2 and supercritical CO_2 (SCF C0_2) at pressures up to 60 MPa was investigated. For comparison, the fluorescence quenching by CBr4 of DMEA was also investigated. The apparent activation volume of the quenching rate constant, kq, was 8 +- 1 and 10+-3 cm_3/mol for DMEAl0_2, and 42 +- 7 and 400 +-90 cm3/mol for DMEAlCBr4 in liquid C0_2 (25 °C, 10 MPa) and SCF C0_2 (35 °C, 8.5 MPa), respectively. For DMEAlQ_2, the plots of In kq against In 1], where 1] is the solvent viscosity, showed a leveling-offwith decreasing.the solvent viscosity, whereas for DMEA)CBr4 they were almost linear in both liquid and SCF C0_2. The results, together with those of the pressure and the pressure-induced solvent viscosity dependences of kq for DMEAl0_2 in n-alkanes (C_4 to C_7) and for DMEAlCBr4 in n-hexane, revealed that the quenching competes with diffusion. The contribution of diffusion to the quenching was analyzed on the basis of a kinetic model with solvent cage in which the quenching occurs. The bimolecular rate constant for the quenching in the solvent cage, kbim, was 6.0 x 10~(10) and 12 x 10~(10) M~I S-I in liquid C0_2 (25 250L鉉, 10 MPa) for DMEAl0_2 and DMEAlCBr4, respectively, and 5.7 x 10~(10) and 12 x 10~(10) M-I S-I in SCF C0_2 (35 °C, 8.5 MPa) for DMEAI O_2 and DMEAlCBr4, respectively. The pressure dependence of kbim and the contribution of diffusion to the quenching are discussed.
机译：研究了在最高60 MPa的压力下，液态C0_2和超临界CO_2（SCF C0_2）中9、10-二甲基蒽（DMEA）的扩散对氧引起的荧光猝灭的贡献。为了比较，还研究了DMEA的CBr4荧光猝灭。液态C0_2（25°C）中DMEAl0_2的淬灭速率常数的表观活化体积kq为8 + -1和10 + -3 cm_3 / mol，而DMEAlCBr4为42 +-7和400 + -90 cm3 / mol ，10 MPa）和SCF C0_2（35°C，8.5 MPa）。对于DMEAlQ_2，In kq相对于In 1]的图（其中1]为溶剂粘度）显示出随着溶剂粘度的降低而趋于平稳，而对于DMEA）CBr4，它们在液体和SCF C0_2中几乎都是线性的。结果以及在正构烷烃（C_4至C_7）中DMEAl0_2和正己烷中DMEAlCBr4的kq的压力和压力诱导的溶剂粘度依赖性的结果表明，淬灭与扩散竞争。基于具有发生淬灭的溶剂笼的动力学模型，分析了扩散对淬灭的贡献。 DMEAl0_2和DMEAlCBr4在液体C0_2（25250L铉，10 MPa）中在溶剂笼中淬灭的双分子速率常数kbim为6.0 x 10〜（10）和12 x 10〜（10）M〜I SI对于DMEAI O_2和DMEAlCBr4，分别在SCF C0_2（35°C，8.5 MPa）中分别为5.7 x 10〜（10）和12 x 10〜（10）MI SI。讨论了kbim的压力依赖性以及扩散对淬灭的贡献。

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