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Updated: Sep 6, 2025

Exploring the Radical Nature of a Carbon Surface by Electron Paramagnetic Resonance and a Calibrated Gas Flow
Published on: April 24, 2014
Observation of Biradical Spin Coupling through Hydrogen Bonds
Yang He1, Na Li1, Ivano E Castelli2
1Center for Carbon-Based Electronics and Key Laboratory for the Physics and Chemistry of Nanodevices, Department of Electronics, Peking University, Beijing 100871, China.
Abstract:
Investigation of intermolecular electron spin interaction is of fundamental importance in both science and technology. Here, radical pairs of all-trans retinoic acid molecules on Au(111) are created using an ultralow temperature scanning tunneling microscope. Antiferromagnetic coupling between two radicals is identified by magnetic-field-dependent spectroscopy. The measured exchange energies are from 0.1 to 1.0 meV. The biradical spin coupling is mediated through O─H⋯O hydrogen bonds, as elucidated from analysis combining density functional theory calculation and a modern version of valence bond theory.
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