Department of Chemistry, Faculty of Science, Gakushuin University, 1-5-1 Mejiro, Toshima-ku, Tokyo 171-8588, Japan.
Analyst. 2016 Jul 21;141(14):4283-92. doi: 10.1039/c6an01051b. Epub 2016 Jun 21.
Charge transfer and charge delocalisation processes play key roles in the functions of large biomolecular systems and organic/inorganic devices. Many of the short-lived transients involved in these processes can be sensitively detected by monitoring their low-energy electronic transitions in the near-IR region. Ultrafast time-resolved near-IR Raman spectroscopy is a promising tool for investigating the structural dynamics of the short-lived transients as well as their electronic dynamics. In this study, we have developed a femtosecond time-resolved near-IR multiplex stimulated Raman spectrometer using the Raman pump pulse at 1190 nm and a broadband probe pulse covering the 900-1550 nm region. Spectral and temporal instrument responses of the spectrometer are estimated to be 5 cm(-1) and 120 fs, respectively. Time-resolved near-IR stimulated Raman spectra of poly(3-dodecylthiophene) (P3DDT) are recorded in toluene solution for investigating its structural changes following the photoexcitation. The spectra strongly indicate conformational changes of P3DDT in excited states associated with the elongation of its effective conjugation length. The results on P3DDT fully demonstrate the effectiveness of the newly developed femtosecond time-resolved near-IR stimulated Raman spectrometer.
电荷转移和电荷离域过程在大型生物分子系统和有机/无机器件的功能中起着关键作用。这些过程中涉及的许多短寿命瞬态可以通过监测它们在近红外区域的低能电子跃迁来敏感地检测到。超快时间分辨近红外拉曼光谱是研究短寿命瞬态结构动力学及其电子动力学的一种很有前途的工具。在这项研究中，我们使用 1190nm 的拉曼泵浦脉冲和覆盖 900-1550nm 区域的宽带探针脉冲，开发了一种飞秒时间分辨近红外多路复用受激拉曼光谱仪。光谱仪的光谱和时间仪器响应分别估计为 5cm(-1)和 120fs。在甲苯溶液中记录了聚(3-十二烷基噻吩)(P3DDT)的近红外受激拉曼光谱，以研究其光激发后的结构变化。这些光谱强烈表明 P3DDT 在激发态下的构象变化与有效共轭长度的伸长有关。P3DDT 的结果充分证明了新开发的飞秒时间分辨近红外受激拉曼光谱仪的有效性。
