Although the optical diffraction limit greatly limits the preparation of nanostructures by optical methods, efforts and progress in this area have never stopped. In such a process, ultrafast lasers play an important role, and "preparing ultrasmall structures with ultrafast" has become a feature. Current efforts in this area can be roughly divided into three categories: (1) photons are used to assist in focusing the beam, that is, nonlinear optical effects; (2) metal probe tips are used to assist in focusing the beam; Molecule as an auxiliary. In general, as auxiliary photons, probe tips, atomic molecules, etc., their scale is getting smaller and smaller, and the size of the corresponding nanostructures can be made smaller and smaller. The femtosecond ultrafast laser ablation method in liquid belongs to category (3). Although there have been many works in the world before, the prepared structures are mostly mediocre nanoparticles, and there are few reports of non-spherical nanostructures. Associate Researcher Zhao Jimin, State Key Laboratory of Surface Physics, Institute of Physics, Chinese Academy of Sciences / Beijing National Laboratory for Condensed Matter Physics (preparation), conducted ultrafast optical research on surfaces and nanosystems using the above method to prepare silver nanostructures. After the non-spherical nanostructure, the existing methods in the world have been improved, and various complicated experimental conditions have been studied and changed to prepare silver nanopores with smaller sizes. Together with Meng Sheng, a researcher in the State Key Laboratory of Surface Physics, he carefully analyzed the microscopic physical mechanism of ultra-small silver nanopore formation observed in the experiment, and constructed a molecular hierarchy model of nanopore formation based on density functional theory, revealing How does the coating agent molecule play a key role; and cooperated with Yang Huaxin, a researcher in the Advanced Materials and Structure Analysis Laboratory, and Xu Hongxing, a researcher in the Nanophysics and Devices Laboratory, to carry out a large number of experimental characterizations and explorations. The nanopore reaches a diameter of 2.3 nm and a depth of 3 nm. Furthermore, the researchers changed the diameter of the silver nanopores by changing the molecular size, and prepared silver nanopores with a diameter of 1.6nm, which confirmed the correctness of the proposed physical mechanism and expanded the application prospects. So far, there is no other top-down experimental method in the world that can achieve such small-sized metal nanostructures. The new method combines the advantages of femtosecond ultrafast lasers and chemical coating agent molecules, where the formation of nanopores is based on a progressive growth physical mechanism. Single silver nanopores with ultra-small diameters may be used in metal-covered near-field optical scanning probes, high-resolution imaging coverage masks, magnetic plasmon resonance research, single-hole biosensors, and other fields. The above work has greatly promoted the progress of preparing nanostructures by optical methods. Related research papers were published in the recent Nano Lett. 11, 3251-3257 (2011), and obtained related invention patents. The above work was supported by the Fund Committee, the Ministry of Science and Technology, the Hundred Talents Program of the Academy of Sciences, and the Innovation Project of the Academy of Sciences. Figure 1: Morphology and diameter distribution of silver nanopores, white round spots are nanopores, and black parts are silver films. Figure 2: The physical mechanism of growth to form nanopores, with the enlarged circular hole in the middle, and A → B → C → C → D → E on the right are different growth sequence stages. Figure 3: The molecular-level microscopic physical mechanism for forming nanopores. The left picture shows the minimum energy value, and the right picture shows the relationship between the molecular size and pore diameter. Charcoal Grill,Charcoal Bbq Grill,Small Charcoal Grill,Old Smokey Grill NingBo AoYue Technology Co., Ltd. , https://www.aoyue-tech.com
Femtosecond ultrafast laser fabrication of ultra-small size silver nanopores made progress
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