Deng Gang-Hua, Qian Yuqin, Wei Qianshun, Zhang Tong, Rao Yi
Department of Chemistry and Biochemistry, Utah State University, Logan, Utah 84322, United States.
J Phys Chem Lett. 2020 Mar 5;11(5):1738-1745. doi: 10.1021/acs.jpclett.0c00157. Epub 2020 Feb 18.
High even-order surface/interface specific spectroscopy has the potential to provide more structural and dynamical information about surfaces and interfaces. In this work, we developed a novel fourth-order interface-specific two-dimensional electronic sum frequency generation (2D-ESFG) for structures and dynamics at surfaces and interfaces. A translating wedge-based identical pulses encoding system (TWINs) was introduced to generate phase-locked pulse pairs for coherent pump beams in 2D-ESFG. As a proof-of-principle experiment, fourth-order 2D-ESFG spectroscopy was used to demonstrate couplings of surface states for both -type and -type GaAs (100). We found surface dark state within the bandgap of the GaAs in 2D-ESFG spectra, which could not be observed in one-dimensional ESFG spectra. To our best knowledge, this is a first demonstration of interface-specific two-dimensional electronic spectroscopy. The development of the 2D-ESFG spectroscopy will provide new structural probes of spectral diffusion, conformational dynamics, energy transfer, and charge transfer for surfaces and interfaces.
高阶表面/界面特异性光谱学有潜力提供更多关于表面和界面的结构及动力学信息。在这项工作中，我们开发了一种新型的四阶界面特异性二维电子和频产生（2D-ESFG）技术，用于研究表面和界面的结构与动力学。引入了基于平移楔形的相同脉冲编码系统（TWINs），以生成用于二维电子和频产生中相干泵浦光束的锁相脉冲对。作为原理验证实验，四阶二维电子和频产生光谱学被用于证明p型和n型GaAs（100）表面态的耦合。我们在二维电子和频产生光谱中发现了GaAs带隙内的表面暗态，这在一维和频产生光谱中无法观察到。据我们所知，这是界面特异性二维电子光谱学的首次证明。二维电子和频产生光谱学的发展将为表面和界面的光谱扩散、构象动力学、能量转移和电荷转移提供新的结构探测手段。
