Scientists discover vibrating atoms can appear active without moving

Scientists at the Max Planck Institutes in Germany have developed a novel quantum simulation method to better interpret tip-enhanced Raman spectroscopy (TERS) images, revealing that vibrating atoms can appear active without actual atomic displacement. TERS, which uses a sharp metallic tip to focus laser light and probe atomic vibrations at the angstrom scale, offers sub-nanometer resolution to study individual molecules and defects in 2D materials. However, the team found that traditional interpretations of TERS images as direct maps of atomic motion are oversimplified because the electronic response of the metal substrate significantly influences the signals. Using first-principles quantum simulations, the researchers demonstrated that common theoretical shortcuts—such as treating molecules in isolation or approximating surfaces with small clusters—can lead to misleading conclusions. Their results show that the metal surface’s electronic screening can dominate the vibrational signal, especially for vibrations perpendicular to the surface, while in-plane vibrations are less affected. This insight challenges previous assumptions and highlights that the brightest spots in TERS