Study on reaction rate enhancement with microwave heating by time resolved spectroscopy method

建立了一套测量微波辐射下瞬态吸收和荧光的实验装置。研究了微波辐射对不同偶极矩分子荧光寿命的影响。微波产生的电场可以改变探针分子的运动。结果表明，微波辐射使荧光寿命变短，说明微波辐射可能加速了溶剂分子和探针分子的旋转运动，并考察了微波加热对苯甲酸酯化反应的影响。研究了常规加热和微波加热的反应速率随温度的变化。根据过渡态理论对反应速率进行了分析。常规加热和微波加热的活化自由能没有差异。然而，发现微波加热的活化熵高于常规加热的活化熵。

An experimental apparatus for measurements of transient absorption and fluorescence under microwave irradiation has been built up. Effect of microwave irradiation on fluorescence lifetime of molecules with different dipole moment has been examined. It can be expected that electric filed produced by microwave could change the molecular motion of the probe molecules. The output power of microwave was in a range from 20 to 100 W It is found that the fluorescence lifetime became shorter by the microwave irradiation, suggesting that the rotational motions of solvent molecules and probe molecules may be accelerated by the microwave irradiation.Effect of microwave heating on esterification of benzoic acid was also examined. Reaction rates as a function of temperature were studied for both conventional and microwave heating. The reaction rates were analysis based on the transition theory. There was no difference in the activation free energy between the conventional and microwave heating. However, it is found that the activation entropy for the microwave heating is higher than that for the conventional heating.