Ohno Paul E, Chang HanByul, Spencer Austin P, Liu Yangdongling, Boamah Mavis D, Wang Hong-Fei, Geiger Franz M
Department of Chemistry , Northwestern University , 2145 Sheridan Road , Evanston , Illinois 60208 , United States.
Department of Chemistry and Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials , Fudan University , Shanghai 200433 , China.
J Phys Chem Lett. 2019 May 16;10(10):2328-2334. doi: 10.1021/acs.jpclett.9b00727. Epub 2019 Apr 25.
We report ionic strength-dependent phase shifts in second harmonic generation (SHG) signals from charged interfaces that verify a recent model in which dispersion between the fundamental and second harmonic beams modulates observed signal intensities. We show how phase information can be used to unambiguously separate the χ and interfacial potential-dependent χ terms that contribute to the total signal and provide a path to test primitive ion models and mean field theories for the electrical double layer with experiments to which theory must conform. Finally, we demonstrate the new method on supported lipid bilayers and comment on the ability of our new instrument to identify hyper-Rayleigh scattering contributions to common homodyne SHG measurements in reflection geometries.
我们报道了来自带电界面的二次谐波产生（SHG）信号中与离子强度相关的相移，这验证了最近的一个模型，即基波与二次谐波光束之间的色散调制了观测到的信号强度。我们展示了如何利用相位信息明确分离对总信号有贡献的χ和与界面电位相关的χ项，并提供了一条通过实验来检验电双层的原始离子模型和平均场理论的途径，而理论必须符合这些实验。最后，我们在支撑脂质双分子层上演示了这种新方法，并评论了我们的新仪器识别反射几何结构中常见零差SHG测量的超瑞利散射贡献的能力。
