Köhntopp Anja, Dittner Mark, Temps Friedrich
Institut für Physikalische Chemie, Christian-Albrechts-Universität zu Kiel , Olshausenstraße 40, D-24098 Kiel, Germany.
J Phys Chem Lett. 2016 Apr 7;7(7):1088-95. doi: 10.1021/acs.jpclett.6b00102. Epub 2016 Mar 9.
We report a first femtosecond time-resolved transient absorption study of the photoinduced ultrafast dynamics of trans-azobenzene (AB) on gold nanoparticles (AuNPs). The observed changes in optical density following excitation at λ = 357 nm were analyzed by using temperature-dependent Mie theory and by Lorentzian band fitting to disentangle the ultrafast relaxation of the local surface plasmon resonance (LSPR) excitation of the Au core and the electronic deactivation of the attached AB ligands. The analysis of the dynamics associated with the AB photochrome yielded lifetime constants of τ1 = 1.2 ± 0.2 ps and τ2 = 4.7 ± 1.1 ps. Both values together indicate surprisingly little difference in the dynamics of the AB ligand on the AuNPs vs in solution. Our results thus highlight the extraordinarily efficient electronic decoupling of the azo chromophore and the Au core by the alkyl linker chain.
我们报道了对反式偶氮苯（AB）在金纳米颗粒（AuNPs）上光诱导超快动力学的首次飞秒时间分辨瞬态吸收研究。通过使用与温度相关的米氏理论以及洛伦兹带拟合，分析了在λ = 357 nm激发后观察到的光密度变化，以解析金核的局域表面等离子体共振（LSPR）激发的超快弛豫以及附着的AB配体的电子失活。对与AB光致变色相关的动力学分析得出寿命常数τ1 = 1.2 ± 0.2 ps和τ2 = 4.7 ± 1.1 ps。这两个值共同表明，AB配体在AuNPs上与在溶液中的动力学差异惊人地小。因此，我们的结果突出了烷基连接链对偶氮发色团和金核的极其有效的电子去耦作用。
