Mastron Joseph N, Tokmakoff Andrei
Department of Chemistry, the James Franck Institute, and the Institute for Biophysical Dynamics University of Chicago , Chicago, Illinois 60637, United States.
J Phys Chem A. 2016 Nov 23;120(46):9178-9187. doi: 10.1021/acs.jpca.6b09158. Epub 2016 Nov 14.
We report on a method for performing ultrafast infrared (IR) vibrational spectroscopy using fluorescence detection. Vibrational dynamics on the ground electronic state driven by femtosecond mid-infrared pulses are detected by changes in fluorescence amplitude resulting from modulation of a two-photon visible transition by nuclear motion. We examine a series of coumarin dyes and study the signals as a function of solvent and excitation pulse parameters. The measured signal characterizes the relaxation of vibrational populations and coherences but yields different information than conventional IR transient absorption measurements. These differences result from the manner in which the ground-state dynamics are projected by the two-photon detection step. Extensions of this method can be adapted for a variety of increased-sensitivity IR measurements.
我们报道了一种利用荧光检测进行超快红外（IR）振动光谱分析的方法。由飞秒中红外脉冲驱动的基态电子态上的振动动力学，通过核运动对双光子可见跃迁的调制所导致的荧光幅度变化来检测。我们研究了一系列香豆素染料，并将信号作为溶剂和激发脉冲参数的函数进行研究。所测量的信号表征了振动布居和相干性的弛豫，但产生的信息与传统红外瞬态吸收测量不同。这些差异源于双光子检测步骤对基态动力学的投影方式。该方法的扩展可适用于各种提高灵敏度的红外测量。
