Dramatic Enhancement of Tip-Enhanced Raman Scattering Mediated by Atomic Point Contact Formation

• DOI: 10.1021/acs.nanolett.0c01791
• Publication Date: 2020-07-17T18:19:21Z
• Authors: Shuyi Liu; Borja Cirera; Yang Sun; Ikutaro Hamada; Melanie Müller; Adnan Hammud; Martin Wolf; Takashi Kumagai
• Keywords: Atomic units

Tip-enhanced Raman scattering (TERS) in ångström-scale plasmonic cavities has drawn increasing attention. However, at vanishing cavity distances remains unexplored. Here, we show the evolution of TERS transition from tunneling regime to atomic point contact (APC). A stable APC is reversibly formed junction between an Ag tip and ultrathin ZnO or NaCl films on Ag(111) surface 10 K. An abrupt increase intensity occurs upon formation for ZnO, but not NaCl. This remarkable observation rationalized by a difference hybridization these films, which determines contribution charge transfer enhancement fused junction. The strong corroborated appearance new vibrational mode formation, whereas it observed chemically inert