Femtosecond IR study of excited-state relaxation and electron-injection dynamics of Ru(dcbpy)2(NCS)2 in solution and on nanocrystalline TiO2 and Al2O3 thin films
Femtosecond IR study of excited-state relaxation and electron-injection dynamics of Ru(dcbpy)2(NCS)2 in solution and on nanocrystalline TiO2 and Al2O3 thin films
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DOI：
10.1021/jp983915x
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发表时间：
1999-04-22
影响因子：
3.3
通讯作者：
Lian, TQ
中科院分区：
文献类型：
--
作者：
Asbury, JB;Ellingson, RJ;Lian, TQ
利用飞秒中红外光谱研究了Ru（dcbpy）（2）（NCS）（2）[dcbpy =（4，4 '-dicarboxy-2，2'-bipyridine）]（或RuN 3）在溶液中以及在纳米Al 2 O3和TiO 2薄膜上的吸附物理和电子注入动力学.在400 nm激发下，Ru N3在乙醇溶液中形成了长寿命的金属-配体电荷转移（MLCT）-M-3激发态，其CN伸缩带在2040 cm（-1）处，激发时间小于100 fs.在1 ns内没有观察到激发态吸收的进一步衰减，这与先前已知的59 ns寿命一致。对于吸附在绝缘衬底Al 2 O3上的RuN 3，3 MLCT态也在小于100 fs的时间内形成。在对比钌N3在乙醇中，这：激发态衰减50%，在1 ns内通过多个指数衰减，而没有观察到基态恢复。这种衰减归因于电子转移到Al 2 O3纳米粒子的带隙中的表面态。对于吸附在TiO_2表面的Ru N_3，瞬态中红外信号主要由注入TiO_2的电子在1700-2400 cm（-1）区域的TR吸收决定。IR信号的上升时间可以用双指数上升函数拟合：50 +/- 25 fs（>84%）和1.7 +/- 0.5 ps（
The photophysics and electron injection dynamics of Ru(dcbpy)(2)(NCS)(2) [dcbpy = (4,4'-dicarboxy-2,2'-bipyridine)] (or Ru N3) in solution and adsorbed on nanocrystalline Al2O3 and TiO2 thin films were studied: by femtosecond mid-IR spectroscopy. For Ru N3 in ethanol after 400 nm excitation, the long-lived metal-to-ligand charge transfer ((MLCT)-M-3) excited state with CN stretching bands at 2040 cm(-1) was formed in less than 100 fs. No further decay of the excited-state absorption was observed within 1 ns consistent with the previously known 59 ns lifetime. For Ru N3 absorbed on Al2O3, an insulating substrate, the 3MLCT state was also formed in less than 100 fs. In contrast to Ru N3 in ethanol, this:excited state decayed by 50% within 1 ns via multiple exponential decay while no ground-state recovery was observed. This decay is attributed to electron transfer to surface states in the band gap of Al2O3 nanoparticles. For Ru N3 adsorbed onto the surface of TiO2, the transient mid-IR signal was dominated by the TR absorption of injected electrons in TiO2 in the 1700-2400 cm(-1) region. The rise time of the IR signal can be fitted by biexponential rise functions: 50 +/- 25 fs(>84%) and 1.7 +/- 0.5 ps (