使用石英手性项进行归一化的宽带红外和频振动光谱方法的验证

Validation of Broadband Infrared Normalization in Sum-Frequency Generation Vibrational Spectroscopy through Simultaneous Chiral Terms on α-Quartz Crystal

和频振动光谱已被广泛用于表征各种界面、然而,对于某些界面。如担载粉末颗粒的界面,由于粉末会散射和频振动光谱信号使得光谱难以准确测量,获取高信噪比的和频振动光谱信号成为了一个巨大的挑战.本文发展了一种新的方法,在和频振动测量时,使用一片z切的α-石英晶体作为基底,担载少量催化剂粉末样品.该方法不仅可以通过石英晶体非共振电场的干涉放大界面颗粒上吸附分子的和频振动信号,并获得相位信息,还可以用于宽带红外和频振动光谱进行归一化.通过分离不同偏振的和频振动信号,能够分离并同时收集手性和非手性的和频振动信号.使用手性的和频振动信号来归一化非手性的和频振动强度,从而避免因担载物质到石英晶体上或由于不同时刻光的不稳定性引起的界面变化或者光重合差异.本文通过测量担载有MoC纳米粒子的石英基底上CH3OD的吸附来验证了本文的方法.无论界面情况如何,都能获得高信噪比的和频振动光谱.

Sum-frequency generation vibrational spectroscopy(SFG-VS)has been widely used for characterizing various interfaces.However,obtaining SFG signals with a high signal-to-noise ratio can be challenging for certain interfaces,such as those involving powder particles,which scatter the SFG light and make it difficult to obtain accurate spectra.To address these challenges,we developed a new approach using a z-cutα-quartz crystal as the substrate loaded with a very small amount of powder sample.This approach not only amplifies the SFG signal from particles through the interference of the electric field from the quartz crystal,but also allows for phase reference and normalization of the broadband infrared SFG spectrum.By distinguishing the different polarizations of the SFG light,we were able to separate and simultaneously collect the achiral and chiral SFG signals.We used the chiral SFG signal to normalize the achiral SFG intensity,thereby avoiding any potential changes to the interface caused by loading substances onto the quartz,as well as coincidence differences resulting from the instability of light at different moments.We demonstrated our method by measuring the adsorption of CH3OD on a quartz substrate loaded with MoC nanoparticles.Our approach produced a high signal-to-noise ratio SFG spectrum,regardless of the interface situation.