Decay of the Exciton in Quaterthiophene-Terminated Alkanethiolate Self-Assembled Monolayers on Au(111)
Decay of the Exciton in Quaterthiophene-Terminated Alkanethiolate Self-Assembled Monolayers on Au(111)
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DOI：
10.1021/acs.jpcc.5b02105
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发表时间：
2015-04-02
影响因子：
3.7
通讯作者：
Munakata, Toshiaki
中科院分区：
文献类型：
--
作者：
Kato, Hiroyuki S.;Murakami, Yoshinari;Munakata, Toshiaki
利用时间分辨双光子光电子能谱（2 PPE）研究了四噻吩封端的硫醇盐在Au（111）表面自组装单分子膜（SAM）中的光激发态动力学.对于具有不同亚烷基（-（CH 2）（n）-）链长的自组装膜，通过红外反射吸收光谱（IRAS）证实了四噻吩（4 T）基团的常见直立构型;-（CH 2）（n）长度控制4 T和Au之间的距离。虽然4 T部分的占据和未占据电子能级的结合能对于所有自组装膜是相似的，但是在4 T处的光激发电子的衰减动力学强烈地依赖于-（CH 2）（n）长度;通过将n从3改变到13，寿命从0.2改变到3.9 ps。n依赖的衰减是由从4 T到Au衬底的激发转移来解释的。
The dynamics of the photoexcited states in the quaterthiophene-terminated alkanethiolate self-assembled monolayer (SAM) on Au(111) are investigated using time-resolved two-photon photoemission (2PPE) spectroscopy. For SAMs with various alkylene (-(CH2)(n)-) chain lengths, a common stand-up configuration of the quaterthiophene (4T) group is confirmed by infrared reflection absorption spectroscopy (IRAS); the -(CH2)(n) length controls the distance between 4T and Au. Although the binding energies of the occupied and unoccupied electronic levels of the 4T moiety are similar for all SAMs, the decay dynamics of the photoexcited electrons at 4T strongly depends on the -(CH2)(n) length; the lifetime changes from 0.2 to 3.9 ps by changing n from 3 to 13. The n dependent decay is explained by the excitation transfer from 4T to the Au substrate.