title: Probing Single-Molecule Dissociations from a Bimolecular Complex NO-Co-Porphyrin.
abstract: Axial coordinations of diatomic NO molecules to metalloporphyrins play key roles in dynamic processes of biological functions such as blood pressure control and immune response. Probing such reactions at the single molecule level is essential to understand their physical mechanisms but has been rarely performed. Here we report on our single molecule dissociation experiments of diatomic NO from NO-Co-porphyrin complexes describing its dissociation mechanisms. Under tunneling junctions of scanning tunneling microscope, both positive and negative energy pulses gave rise to dissociations of NO with threshold voltages, +0.68 and -0.74 V at 0.1 nA tunneling current on Au(111). From the observed power law relations between dissociation rate and tunneling current, we argue that the dissociations were inelastically induced with molecular orbital resonances by stochastically tunneling electrons, which is supported with our density functional theory calculations. Our study shows that single molecule dissociation experiments can be used to probe reaction mechanisms in a variety of axial coordinations between small molecules and metalloporphyrins.
authors.affiliation: †Department of Physics, Korea University, 1-5 Anam-dong, Seongbuk-gu, Seoul, 136-713, Republic of Korea.
authors.forename: Howon
authors.initials: H
authors.lastname: Kim
authors.affiliation: ‡Graduate School of Nanoscience and Technology, KAIST, Daejeon 305-701, Republic of Korea.
authors.forename: Yun Hee
authors.initials: YH
authors.lastname: Chang
authors.affiliation: †Department of Physics, Korea University, 1-5 Anam-dong, Seongbuk-gu, Seoul, 136-713, Republic of Korea.
authors.forename: Won-Jun
authors.initials: WJ
authors.lastname: Jang
authors.affiliation: ‡Graduate School of Nanoscience and Technology, KAIST, Daejeon 305-701, Republic of Korea.
authors.forename: Eui-Sup
authors.initials: ES
authors.lastname: Lee
authors.affiliation: ‡Graduate School of Nanoscience and Technology, KAIST, Daejeon 305-701, Republic of Korea.
authors.forename: Yong-Hyun
authors.initials: YH
authors.lastname: Kim
authors.affiliation: †Department of Physics, Korea University, 1-5 Anam-dong, Seongbuk-gu, Seoul, 136-713, Republic of Korea.
authors.forename: Se-Jong
authors.initials: SJ
authors.lastname: Kahng
keywords: bimolecular reaction; density functional theory; dissociation; metalloporphyrin; nitric oxide; scanning tunneling microscopy