To study vibrations indirectly, scientists use spectroscopic techniques<\/a> like Raman scattering. However, traditional methods collect signals from large groups of atoms at once, which limits their spatial resolution.<\/p>\n To address the challenge, the team turned to tip-enhanced Raman spectroscopy<\/a> (TERS). This powerful analytical method combines laser light with a sharp metallic tip that concentrates the electromagnetic field into a tiny volume. <\/p>\n This allows scientists to probe atomic vibrations with sub-nanometer resolution, reaching the \u00c5ngstr\u00f6m scale, about one ten-billionth of a meter. At this level, they can even examine individual molecules or defects in 2D materials.<\/p>\n Yet, interpreting highly detailed TERS images requires reliable theoretical models that can connect measured signals to atomic-scale motion. There are several factors that can alter the produced signals, especially the electronic response of the metallic substrate beneath the sample.<\/p>\n Atomic motion redefined<\/p>\n To overcome this limitation, the team used first-principles quantum simulations<\/a>. Rather than relying on oversimplified models, they built a realistic computational approach. It stimulates systems containing hundreds of atoms using only the fundamental laws of quantum mechanics. <\/p>\n The study found that common theoretical shortcuts, such as treating molecules as isolated systems or approximating surfaces with small clusters, can, in fact, lead to misleading results and oversimplified interpretations. <\/p>\n \u201cOur results show that the electronic response of the surface can dominate the signal and fundamentally change what these images mean,\u201d Rossi concluded in a press release<\/a>.<\/p>\n The results showed that TERS is sensitive to the symmetry of local environments. This allowed the researchers to spot small structural changes and identify defects in 2D materials. <\/p>\n Additionally, electronic screening from the metal surface greatly altered images of vibrations that moved perpendicular to the surface. Meanwhile, those vibrations confined to the molecular plane were far less affected.<\/p>\n According to Brezina, spatially non-local interactions between atoms can strongly shape TERS signals at specific points in space. He added that the brightest areas in an image do not necessarily reflect the largest atomic movements.<\/p>\n The study provides a pathway to more accurate imaging of vibrational motion. It could impact several emerging fields, such as defect mapping in 2D materials, the design of single-molecule electronics, operando surface catalysis studies, as well as next-gen genome sequencing technologies.<\/p>\n![\"\"](\"https:\/\/www.newsbeep.com\/nz\/wp-content\/uploads\/2026\/02\/Z11_e718c2.jpg\" "\\"Quantum")
First-principle calculations inform the creation of correct TERS images.
Credit: Rossi et al.<\/a><\/p>\n