Sequential transmission electron microscopy observation of the shape change of gold nanorods under pulsed laser light irradiation
Sequential transmission electron microscopy observation of the shape change of gold nanorods under pulsed laser light irradiation
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DOI：
10.1093/jmicro/dfy136
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发表时间：
2019-04-01
期刊：
影响因子：
1.8
通讯作者：
Matsumura, Syo
中科院分区：
文献类型：
--
作者：
Aso, Kohei;Shigematsu, Koji;Matsumura, Syo
使用连接到脉冲激光照明系统的高压电子显微镜在近红外脉冲激光照射下对金纳米棒进行原位连续高分辨率观察。最初的纳米棒是单晶；长轴沿[001]定向。在= 1064 nm、平均每脉冲强度为980或490 J/m(2)的激光照射下，纳米棒的形状从棒状变为被{111}和{001}面包围的桶状，同时保持了原始的单晶结构。有方向的侧面被重建为由狭窄的{111}面组成的之字形精细结构。假设粒子沿其长轴具有旋转对称性，则根据图像评估了照射期间体积和表面积的时间演变。在形状变化过程中，使用 980 J/m(2) 的脉冲发射，表面积逐步减小，同时保持体积。另一方面，当平均强度降低至每个脉冲 490 J/m(2) 时，需要多次重复射击才能引起形状变化。除了表面积之外，在后一种情况下，由于原子蒸发而导致形状变化，体积也减少了。时间变化的定量分析表明脉冲激光照射引起的金纳米棒的原子激发或加热的不均匀性。
In situ sequential high-resolution observations were performed on gold nanorods under near-infra-red pulsed laser irradiation using a high-voltage electron microscope attached to a pulsed laser illumination system. The original nanorods were single crystals; the longer axes were oriented along [001]. Under laser light irradiation with = 1064 nm with an average intensity per pulse of 980 or 490 J/m(2), the shape of the nanorods changed from rod to barrel surrounded by the {111} and {001} facets, while the original single-crystalline structure was maintained. The side surfaces with direction were reconstructed into zig-zag fine structures consisting of narrow {111} facets. The temporal evolution of the volume and surface area during irradiation was evaluated based on the images, assuming that the particles have a rotational symmetry along their longer axes. The surface area was stepwise decreased during the shape change using pulse shots of 980 J/m(2) while the volume was maintained. On the other hand, several repeated shots were required to induce the shape change when the averaged intensity was reduced to 490 J/m(2) per pulse. In addition to the surface area, the volume was reduced under the latter condition during the shape change due to the evaporation of atoms. The quantitative analysis of the temporal changes indicates the heterogeneity of the atomic excitation or heating of gold nanorods induced by pulsed laser illumination.