UC San Diego

Interfacial probe at elemental selectivity is highly sought after experimental tool. Chemical phenomena happen at the interface and our understanding these processes is often challenging. Second harmonic generation (SHG) spectroscopy technique can selectively probe the interface due to symmetry breaking. Coupling this technique with core electron XUV/X-ray spectroscopy allows elemental selectivity. In this regard, the development of novel core level second harmonic generation spectroscopy demonstrates a powerful tool at atomic resolution. Theoretical framework for simulation of XUV/X-ray SHG is developed to study different interfaces and interpret the experimental result. In this research, we explored Li ion displacement in ferroelectric perovskite LiOsO3 is studied via XUV-SHG, boron electronics structure at inorganic/organic junction and Li mobility in solid-state electrolyte lithium lanthanum titanate. In all cases, the bulk responses were indistinguishable between different interfaces while the surface sensitive SHG technique demonstrate different responses. Our approach shows a promising result toward elemental selective interfacial probe.