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Updated: Aug 15, 2026

Characterizing Single-Molecule Conformational Changes Under Shear Flow with Fluorescence Microscopy
Published on: January 25, 2020
Mechanisms of reversible conformational transitions in a single molecule
1Department of Physics and Astronomy and Department of Chemistry, University of California, Irvine, CA 92697-4575, USA.
Abstract:
The reversible interconversion between two nonplanar conformations of single Zn(II) Etioporphyrin I molecules adsorbed on a NiAl(110) surface at 13 K was induced by a scanning tunneling microscope (STM). The threshold voltage for the conformational change at negative sample bias depends linearly on the tip-sample distance, suggesting an electrostatic force mechanism. The reverse conversion involves inelastic electron tunneling via a molecular electronic resonance at 1.25 eV. In contrast with the photon-induced conformational changes, an electrically induced mechanism is realized with the STM.
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