芘在离子液体与常规溶剂混合体系的脉冲辐解研究

Pulse radiolysis study on pyrene in ionic liquid and organic solvents mixture solutions

以芘(Pyrene)作为探针分子,利用纳秒脉冲辐解技术研究了芘在乙腈、丙酮、环己烷、乙醇、及乙醇与季铵盐离子液体(三乙基庚基铵双三氟甲磺酰亚胺)混合体系中各种瞬态产物的吸收光谱,并观察了溶剂化电子的反应动力学。测定了芘在乙醇与离子液体混合溶剂中490nm处芘阴离子自由基(Py?-)生成的速率常数,随着溶液中离子液体体积的增大,芘阴离子自由基生成速率常数减缓。同时比较了乙醇及混合体系中离子液体不同体积比下Py?-生成表观速率常数的变化,进一步揭示了离子液体不同于普通溶剂的物理化学特性:离子液体中经电子束辐解后产生溶剂化电子,而溶剂化电子产生之前存在一个极短的干电子过程。

Pulse radiolysis experiments were conducted on the probe molecule, pyrene, in acetonitrile, acetone, cyclohexane, ethanol and mixed solutions containing ammonium ionic liquid with different volume.The formation of pyrene radical anion （Py^·-） was observed at 490nm and the rate constants of the Py^·-formation were determined in the ethanol solution and in the mixture solution with different ionic liquid volume fractions, respectively.Moreover, the rate constants are changed greatly with increasing of the ILs concentration in the mixture solutions.The results can be assumed that the dry electrons produce in very short time scales after electron pulse and the solvated electrons can react with pyrene to generate its radical anion in nanosecond time scale.