Quantification of surface reactivity of thin films modulated by physics has made progress
Recently, the Ma Xucun Research Group of the Surface Physics Laboratory of the Beijing National Laboratory for Condensed Matter Physics and the Physics Department of Tsinghua University, Xue Qikun, Jia Jinfeng, and Chen Xi, have cooperated to implement and prove the quantum effect induced magnetic organic molecules. Selective self-assembly growth, this work is the use of quantum effects to modulate the surface reactivity of the thin film. Related research results were published in the Journal of the American Chemical Society published on June 25, 2008 (JACS 130, 7790-7791 (2008)).
In the field of molecular electronics, material preparation of many organic molecular devices is achieved through surface self-assembly processes. In addition to the interaction between molecules and molecules, the electronic structure and properties of the substrate are another major factor affecting the self-assembly behavior of the molecules. When the thickness of the substrate is reduced to be comparable to its Fermi wavelength, the quantum size effect will appear and will have an important influence on the self-assembly process of the molecule. Sometimes this effect is even decisive.
Last year, Ma Xucun's research group and collaborators discovered that when oxygen is adsorbed on the surface of Pb films with different thicknesses, the quantum effect causes the film surface chemical reactivity to oscillate with thickness changes [PNAS 104, 9204-9208 (2007)]. On this basis, they further studied the adsorption behavior of the magnetic organic molecule CoPc, and observed that the adsorption process has a strong selectivity for the thickness of the Pb film. Based on this phenomenon, they completely ruled out the influence of the diffusion and other dynamic processes on the adsorption behavior, demonstrating that this is entirely the result of the quantum size effect.
This study is of great significance for the design of the surface adsorption structure of magnetic molecules, the understanding of the coupling of magnetic molecules with the substrate, and the use of quantum size effects to regulate the magnetic properties of the self-assembled films. This work has been funded by the National Natural Science Foundation of China, the "973" Project of the Ministry of Science and Technology and the Knowledge Innovation Project of the Chinese Academy of Sciences.
In the field of molecular electronics, material preparation of many organic molecular devices is achieved through surface self-assembly processes. In addition to the interaction between molecules and molecules, the electronic structure and properties of the substrate are another major factor affecting the self-assembly behavior of the molecules. When the thickness of the substrate is reduced to be comparable to its Fermi wavelength, the quantum size effect will appear and will have an important influence on the self-assembly process of the molecule. Sometimes this effect is even decisive.
Last year, Ma Xucun's research group and collaborators discovered that when oxygen is adsorbed on the surface of Pb films with different thicknesses, the quantum effect causes the film surface chemical reactivity to oscillate with thickness changes [PNAS 104, 9204-9208 (2007)]. On this basis, they further studied the adsorption behavior of the magnetic organic molecule CoPc, and observed that the adsorption process has a strong selectivity for the thickness of the Pb film. Based on this phenomenon, they completely ruled out the influence of the diffusion and other dynamic processes on the adsorption behavior, demonstrating that this is entirely the result of the quantum size effect.
This study is of great significance for the design of the surface adsorption structure of magnetic molecules, the understanding of the coupling of magnetic molecules with the substrate, and the use of quantum size effects to regulate the magnetic properties of the self-assembled films. This work has been funded by the National Natural Science Foundation of China, the "973" Project of the Ministry of Science and Technology and the Knowledge Innovation Project of the Chinese Academy of Sciences.
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