Photoisomerization dynamics study on cis-azobenzene derivative using ultraviolet-to-visible tunable femtosecond pulses
Photoisomerization dynamics study on cis-azobenzene derivative using ultraviolet-to-visible tunable femtosecond pulses
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DOI：
10.1016/j.apsusc.2009.04.108
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发表时间：
2009-09
影响因子：
6.7
通讯作者：
A. Yamaguchi;N. Nakagawa;Kazuma Igarashi;T. Sekikawa;Hidenori Nishioka;H. Asanuma;M. Yamashita
中科院分区：
文献类型：
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作者：
A. Yamaguchi;N. Nakagawa;Kazuma Igarashi;T. Sekikawa;Hidenori Nishioka;H. Asanuma;M. Yamashita
对4-羧基-2 ′，6 ′-二甲基偶氮苯顺式异构体进行了瞬态吸收测量和一级速率方程（RE）分析，以阐明S1 C激发态光致异构化过程和热弛豫过程的定量差异. RE分析确定了在430 nm、150 fs、能量为200 nJ的抽运光脉冲下，每个抽运光脉冲的顺反异构化率为3%。此外，由以下观察结果归属了瞬态吸收中出现的由产生的反式分子引起的信号：380 nm探针处的瞬态吸光度变化在430 nm脉冲泵浦后的300 fs内大部分下降，然后缓慢下降到零，而350 nm探针处的吸光度变化在超过1皮秒的时间区域内具有正的常数分量。RE分析表明，该常数分量是由于生成的反式分子，其正值是由于反式分子中S 0 T-S 2 T跃迁的吸收截面大于原顺式分子中S 0 C-S 2C跃迁的吸收截面。
We performed the transient absorption measurement and the first rate equation (RE) analysis for cis isomer of 4-carboxy-2′,6′-dimethylazobenzene to clarify the quantitative difference between the photoisomerization process and the thermal relaxation process from the S1Cexcited state. The RE analysis enabled us to determine the cis-to-trans photoisomerization rate per each pump pulse to be 3% under the condition of the 430nm, 150fs pump pulse with energy of 200nJ. Moreover, the signal due to the yielded trans molecules appearing in the transient absorption was assigned from the following observed result: the transient absorbance change at the 380nm probe mostly decreased within 300fs after the 430nm pulse pumping and then slowly decreased to zero, while the absorbance change at the 350nm probe had a positive constant component in the over one picosecond time region. The RE analysis showed that this constant component is due to the yielded trans molecules, and its positive value is due to the fact that the absorption cross-section of the S0T-to- S2Ttransition in their trans molecules is larger than that of the S0C-to- S2Ctransition in the original cis molecules.