The knowledge of charge dynamics at surface/interfacial states and, particularly, their energy levels and relaxation processes are critical for understanding the fundamental mechanisms of inorganic and organic semiconductors in the process of energy conversion, catalysis, and photosynthesis. Many of the electronic and energy transfer dynamics at surfaces/interfaces have not been well understood. The main difficulty lies in the fact that we are lacking a surface/interface-sensitive tool for the dynamics. Here we report an experimental implementation of two-dimensional electronic sum frequency generation spectroscopy (2D-ESFG) for surface carrier dynamics, based on our recently developed ESFG system. The pump pulse pair are created using TWINS (Translating Wedge Based Identical Pulses eNcoding System). The 2D-ESFG technique was used for p-type GaAs. Our experiments revealed the surface dark surface within the bandgap. The electron migration between surface states were also observed between the surface states. The multidimensional spectroscopy extended research areas into surfaces/interfaces that accesses the electronic resonances of interfacial molecules, opens up a new avenue for probing dynamics and energy and charge transfer at surfaces/interfaces. Along with theoretical developments, we believe that 2D-ESFG spectroscopy will become another useful tool in the fields of surface science and multidimensional spectroscopy.

Development of two-dimensional electronic sum frequency generation spectroscopy (2D-ESFG) for surface charge dynamics

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.