Department of Physics and Astronomy, Faculty of Sciences, VU University, De Boelelaan 1081, 1081HV Amsterdam, The Netherlands.
Phys Chem Chem Phys. 2011 Oct 28;13(40):18123-33. doi: 10.1039/c1cp21650c. Epub 2011 Sep 12.
A new wavelength modulator based on a custom-made chopper blade and a slit placed in the Fourier plane of a pulse shaper was used to detect explicitly the first derivative of the time-resolved femtosecond stimulated Raman spectroscopy (FSRS) signals. This approach resulted in an unprecedented reduction of the non-coherent background that results from population transfer by the Raman pump inherent to FSRS experiments. The method of Fourier peak filtering was implemented as a powerful tool for reducing both the remaining non-coherent and coherent background associated with FSRS experiments. The method was demonstrated on β-carotene and a similar synthetic aryl carotenoid. The experiments confirm earlier FSRS results on β-carotene but suggest some reinterpretation. Strong bleaching signals of ground state vibrations were observed and interpreted as an inseparable part of the time-resolved FSRS experiment. New long-lived Raman features were observed in β-carotene and the synthetic aryl carotenoid and assigned to a combination of conformational changes and solvent rearrangement. More complex wavelength modulation methods are proposed in the development of more robust FSRS experiments.
一种基于定制斩波器刀片和放置在脉冲整形器傅里叶平面中的狭缝的新型波长调制器被用于明确检测飞秒受激拉曼光谱（FSRS）信号的一阶导数。这种方法显著减少了由 FSRS 实验中拉曼泵引起的非相干背景，该背景会导致粒子数转移。傅里叶峰滤波方法作为一种强大的工具，可用于减少与 FSRS 实验相关的剩余非相干和相干背景。该方法已在β-胡萝卜素和类似的合成芳基类胡萝卜素上得到验证。实验证实了之前关于β-胡萝卜素的 FSRS 结果，但提出了一些重新解释。观察到强的基态振动的漂白信号，并将其解释为时间分辨 FSRS 实验不可分割的一部分。在β-胡萝卜素和合成芳基类胡萝卜素中观察到新的长寿命拉曼特征，并将其分配给构象变化和溶剂重排的组合。在更稳健的 FSRS 实验的发展中提出了更复杂的波长调制方法。
