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A single chlorophyll-a molecule is switched into four different conformations by injecting tunneling electrons from a STM-tip. Just a single tunneling electron energy transfer to the molecule causes the conformation change. The molecule requires 0.8 eV energy for each switching event on Au(111) surface. We inject up to 1.5 eV energy tunneling electrons during this switching experiment [44].

(Courtesy: Violeta Iancu & Saw-Wai Hla)

Read the paper --> (pdf file)

[44] V. Iancu, and S.-W. Hla, “Realizing of a Four-Step Molecular Switch in Scanning Tunneling Microscope Manipulation of Single Chlorophyll-a Molecules:”, PNAS 103 (2006) 13718-13721.