Real-Space Observation of Quantum Tunneling Induced Single-Molecule Conformational Transitions between Two Levels in a Double-Well Potential
ORAL
Abstract
Quantum tunneling is a fundamental phenomenon in various chemical, physical, and biological processes [1–3]. A prominent example is the inversion of ammonia molecules, which manifests as spectral doublets in their rotational and vibrational spectra. Similarly, quantum tunneling has been observed in the diffusion of hydrogen atoms on Cu(001) and the inclined motion of hydroxyl groups on Cu(110) [4,5]. The tunneling probability is strongly dependent on factors such as particle mass, barrier height, temperature and tunneling distance. In this study, we present real-space observation of a single pyrrolidine molecule undergoing conformational tunneling between two distinct states on a Cu(001) surface, using a home-built variable-temperature scanning tunneling microscope (STM). Switching between two tunneling current levels in the STM junction reveal the two-state conformational transitions of pyrrolidine (C4H8NH) and the isotope pyrrolidine-d8 (C4D8NH). Temperature-dependent measurements indicate a transition from thermally activated switching to quantum tunneling-assisted switching within a double-well potential, providing insight into the underlying mechanisms governing these conformational transitions.
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Publication: [1] P. S. Zuev, R. S. Sheridan, T. V. Albu, D. G. Truhlar, D. A. Hrovat, and W. T. Borden, Carbon Tunneling from a Single Quantum State, Science 299, 867 (2003).<br>[2] Z. D. Nagel and J. P. Klinman, Tunneling and Dynamics in Enzymatic Hydride Transfer, Chem. Rev. 106, 3095 (2006).<br>[3] P. Esquinazi, Tunneling Systems in Amorphous and Crystalline Solids (Springer Berlin Heidelberg, Berlin, Heidelberg s.l, 1998).<br>[4] T. Kumagai, M. Kaizu, H. Okuyama, S. Hatta, T. Aruga, I. Hamada, and Y. Morikawa, Tunneling dynamics of a hydroxyl group adsorbed on Cu(110), Phys. Rev. B 79, 035423 (2009).<br>[5] L. J. Lauhon and W. Ho, Direct Observation of the Quantum Tunneling of Single Hydrogen Atoms with a Scanning Tunneling Microscope, Phys. Rev. Lett. 85, 4566 (2000)
Presenters
Jiawei Zeng
Univerisity of California, Irvine, University of California, Irvine
Authors
Jiawei Zeng
Univerisity of California, Irvine, University of California, Irvine
