Real-Space Observation of Quantum Tunneling by a Carbon Atom: Flipping Reaction of Formaldehyde on Cu(110)

Chenfang Lin; Emile Durant; Mats Persson; Mariana Rossi; Takashi Kumagai

doi:10.1021/acs.jpclett.8b03806

Real-Space Observation of Quantum Tunneling by a Carbon Atom: Flipping Reaction of Formaldehyde on Cu(110)

J Phys Chem Lett. 2019 Feb 7;10(3):645-649. doi: 10.1021/acs.jpclett.8b03806. Epub 2019 Jan 29.

Authors

Chenfang Lin¹, Emile Durant², Mats Persson², Mariana Rossi³, Takashi Kumagai^{1

4}

Affiliations

¹ Department of Physical Chemistry , Fritz-Haber Institute of the Max-Planck Society , Faradayweg 4-6 , 14195 Berlin , Germany.
² Surface Science Research Centre and Department of Chemistry , University of Liverpool , Liverpool L69 3BX , U.K.
³ Theory Department , Fritz-Haber Institute of the Max-Planck Society , Faradayweg 4-6 , 14195 Berlin , Germany.
⁴ JST-PRESTO , 4-1-8 Honcho , Kawaguchi , Saitama 332-0012 , Japan.

Abstract

We present a direct observation of carbon-atom tunneling in the flipping reaction of formaldehyde between its two mirror-reflected states on a Cu(110) surface using low-temperature scanning tunneling microscopy (STM). The flipping reaction was monitored in real time, and the reaction rate was found to be temperature independent below 10 K. This indicates that this reaction is governed by quantum mechanical tunneling, albeit involving a substantial motion of the carbon atom (∼1 Å). In addition, deuteration of the formaldehyde molecule resulted in a significant kinetic isotope effect ( R_CH₂O/ R_CD₂O ≈ 10). The adsorption structure, reaction pathway, and tunneling probability were examined by density functional theory calculations, which corroborate the experimental observations.