Direct Observation of Carbonate Chemisorption on Barium Titanate Surfaces by Tip‐Enhanced Raman Spectroscopy

Abstract

Abstract Surface chemistry significantly influences the physicochemical and functional properties of nanoparticles, thus necessitating the investigation of surfaces, especially when subjected to chemisorption. Seeking a method that delivers both high‐resolution imaging and precise chemical information, tip‐enhanced Raman spectroscopy (TERS) emerges as a critical technique. By the combination of scanning probe microscopy with Raman spectroscopy, TERS effectively addresses the limitations of traditional optical microscopes in the study of nanoparticles. The results provide detailed nanoscale structural insights, shed light on surface chemistry, and enable the detection of Raman‐forbidden modes caused by the substantial electric field at the tip apex (≈3 × 108 V m−1). This electric field plays a crucial role in altering selection rules, thereby broadening the scope of TERS beyond merely detecting Raman modes. By combining topographical with TERS mapping, the presence of a carbonate monolayer on the barium titanate (BaTiO3) nanoparticle surface is unveiled – an observation elusive to common characterization techniques.

Keywords

• barium titanate
• high‐resolution surface imaging
• plasmonic enhancement
• Raman‐forbidden modes
• tip‐enhanced Raman spectroscopy