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利用纳秒级激光光解瞬态吸收光谱装置,研究了以乙腈作为溶剂,以2-萘乙酮作为敏化剂的体系在355nm激光作用下敏化产生β-胡萝卜素激发三重态的机制,并进一步研究了β-胡萝卜素激发三重态的性质。研究显示2-萘乙酮和β-胡萝卜素的二元体系在355nm激光作用下,2-萘乙酮首先被激发为其激发三重态(420nm),2-萘乙酮激发三重态与β-胡萝卜素发生激发能转移,产生β-胡萝卜素激发三重态(510nm)。通过激发能转移的方法测得了β-胡萝卜素激发三重态在最大吸收波长510nm处的摩尔消光系数为23000L·mol-1·cm-1。改变β-胡萝卜素的浓度测得了其激发三重态在乙腈体系中的衰变反应速率常数6·5×104s-1,其在乙腈体系中的三重态寿命为15·6μs。同时获得了激发态2-萘乙酮与β-胡萝卜素之间激发能转移反应的速率常数1·5×1010L·mol-1·s-1。
The nanosecond laser photolysis transient absorption spectrometer was used to study the mechanism of sensitization to the excited triplet state of β-carotene under the action of 355 nm laser with acetonitrile as the solvent and 2-acetonaphthone as the sensitizer. The properties of β-carotene excited triplet state were further studied. The results showed that 2-acetonaphthone was first excited to triplet state (420nm) at excitation of 355nm, and the excited state of 2- Carotenoid excitation energy transfer, resulting in β-carotene excitation triplet state (510nm). The molar extinction coefficient of β-carotene excited triplet state at the maximum absorption wavelength of 510nm was 23000L · mol-1 · cm-1 by excitation energy transfer method. The decay reaction rate constant of the excited triplet state in acetonitrile was measured by changing the concentration of β-carotene. The triplet state lifetime in acetonitrile was 15.6μs. At the same time, a rate constant of 1.5 × 1010L · mol-1 · s-1 was obtained for the excitation energy transfer reaction between 2-acetonaphthone and β-carotene.