Takaya Tomohisa, Iwata Koichi
Department of Chemistry, Faculty of Science, Gakushuin University;
J Vis Exp. 2020 Feb 10(156). doi: 10.3791/60437.
Femtosecond time-resolved stimulated Raman spectroscopy is a promising method of observing the structural dynamics of short-lived transients with near infrared (near-IR) transitions, because it can overcome the low sensitivity of spontaneous Raman spectrometers in the near-IR region. Here, we describe technical details of a femtosecond time-resolved near-IR multiplex stimulated Raman spectrometer that we have recently developed. A description of signal generation and optimization, measurement, data acquisition, and calibration and correction of recorded data is provided as well. We present an application of our spectrometer to analyze the excited-state dynamics of β-carotene in toluene solution. A C=C stretch band of β-carotene in the second lowest excited singlet (S2) state and the lowest excited singlet (S1) state is clearly observed in the recorded time-resolved stimulated Raman spectra. The femtosecond time-resolved near-IR stimulated Raman spectrometer is applicable to the structural dynamics of π-conjugate systems from simple molecules to complex materials.
飞秒时间分辨受激拉曼光谱是一种很有前景的方法，可用于观测具有近红外（near-IR）跃迁的短寿命瞬态的结构动力学，因为它能够克服自发拉曼光谱仪在近红外区域的低灵敏度问题。在此，我们描述了我们最近开发的飞秒时间分辨近红外多路复用受激拉曼光谱仪的技术细节。同时还提供了信号产生与优化、测量、数据采集以及记录数据的校准与校正的相关描述。我们展示了该光谱仪在分析甲苯溶液中β-胡萝卜素激发态动力学方面的应用。在记录的时间分辨受激拉曼光谱中清晰地观察到了处于第二低激发单重态（S2）和最低激发单重态（S1）的β-胡萝卜素的C = C伸缩带。飞秒时间分辨近红外受激拉曼光谱仪适用于从简单分子到复杂材料的π共轭体系的结构动力学研究。
