Submolecular Resolution by Variation of the Inelastic Electron Tunneling Spectroscopy Amplitude and its Relation to the AFM/STM Signal

• Published in: Physical review letters Vol. 119; no. 16; p. 166001
• Main Authors: de la Torre, Bruno, Švec, Martin, Foti, Giuseppe, Krejčí, Ondřej, Hapala, Prokop, Garcia-Lekue, Aran, Frederiksen, Thomas, Zbořil, Radek, Arnau, Andres, Vázquez, Héctor, Jelínek, Pavel
• Format: Journal Article
• Language: English
• Published: United States 16.10.2017
• ISSN: 1079-7114
• DOI: 10.1103/physrevlett.119.166001

Here we show scanning tunneling microscopy (STM), noncontact atomic force microscopy (AFM), and inelastic electron tunneling spectroscopy (IETS) measurements on an organic molecule with a CO-terminated tip at 5 K. The high-resolution contrast observed simultaneously in all channels unambiguously demonstrates the common imaging mechanism in STM/AFM/IETS, related to the lateral bending of the CO-functionalized tip. The IETS spectroscopy reveals that the submolecular contrast at 5 K consists of both renormalization of vibrational frequency and variation of the amplitude of the IETS signal. This finding is also corroborated by first principles simulations. We extend accordingly the probe-particle AFM/STM/IETS model to include these two main ingredients necessary to reproduce the high-resolution IETS contrast. We also employ the first principles simulations to get more insight into a different response of frustrated translation and rotational modes of the CO tip during imaging.