Study of Photo-induced tautomerization of H₂Pc on NaCl using 1K optics-integrated STM

Scanning Tunneling Microsopy (STM) is state-of-the-art technique that could image surfaces at the atomic level. When combined with optical spectroscopy, STM becomes an exceptional tool for probing optical phenomena with atomic resolution. By using a custom-built, optics-integrated STM operating at 1 K under ultra-high vacuum, we investigate the photoinduced tautomerization of a single phthalocyanine (H₂Pc) molecule on NaCl/Ag(111). Understanding and controlling tautomerization in the single molecule level provide fundamental insight into intramolecular transformations and molecular-scale switching applications. Our setup features a novel optical alignment technique that ensures precise optical positioning, and enhances excitation efficiency. The functionality of our setup was validated through the observation of electroluminescence from a silver Ag(111) surface and the tautomerization of H₂PC triggered by optical excitation using a gold tip. This approach aims to provide a robust platform for studying light-matter interactions at the atomic scale.