Production of ultrathin nanowires from refractory metals (Nb, Re, W, Mo) by laser ablation in superfluid helium
Production of ultrathin nanowires from refractory metals (Nb, Re, W, Mo) by laser ablation in superfluid helium
复制标题
通过在超流氦中激光烧蚀从难熔金属（Nb、Re、W、Mo）生产超细纳米线
DOI：
--
复制
发表时间：
2015
期刊：
影响因子：
--
通讯作者：
I. Khodos
中科院分区：
文献类型：
--
作者：
E. Gordon;A. Karabulin;V. Matyushenko;V. Sizov;I. Khodos
用短脉冲激光在超流氦中烧蚀目标，可以将任何金属的原子和小簇引入液体。然后，金属被集中在激光聚焦中形成核的一维量子化漩涡的核心，并扩展到液体中。随后，金属在涡流内凝固，形成了形状和结构完美的纳米线。对于难熔金属，这些电线应该特别细。用铌、钼和钨制成的纳米线的直径确实分别为4.0、2.0和2.5 nm。不幸的是，在未退火铼的烧蚀下，主要产品是扁平的“薄片”，形状不规则，尺寸为20-50纳米。短纳米线（直径为1.5纳米）少量存在。用这种方法生产的金属丝不含额外的杂质，并且具有自由的侧表面。利用二极管泵浦Nd:LSB微激光器（波长1.06 μm，脉冲持续时间0.4 ns，脉冲能量100 μJ，重复频率4 kHz），可以在一次低温实验中产生足够数量的纳米网，用于多种物理和化学应用。钼和钨的超薄线有望制造“冷”阴极，而铌纳米网应该是一种出色的催化剂。
The ablation of targets in superfluid helium with a short-pulse laser allows introducing into liquid the atoms and small clusters of any metal. The metal is then concentrated in the core of 1D quantized vortices nucleating in the laser focus and expanding into the liquid. Subsequent metal coagulation within the vortex results in the formation of thin nanowires with perfect shape and structure. For refractory metals these wires are expected to be especially thin. The diameters of nanowires grown from niobium, molybdenum and tungsten are indeed 4.0, 2.0 and 2.5 nm, respectively. Unfortunately, under ablation of unannealed rhenium the main product is flat ‘flakes’ having irregular shape and 20–50 nm size. Short nanowires (with a 1.5 nm diameter) were present in small amounts. The wires produced by this method contain no additional impurities and have a free lateral surface. By using a diode-pumped Nd:LSB microlaser (1.06 μm wavelength, 0.4 ns pulse duration, 100 μJ pulse energy and 4 kHz repetition rate) the amounts of nanoweb sufficient for many physical and chemical applications could be produced in a single low-temperature experiment. Ultrathin wires of molybdenum and tungsten show promise for creating ‘cold’ cathodes whereas a niobium nanoweb should be an excellent catalyst.