Juhász Laura, Moldován Krisztián, Gurikov Pavel, Liebner Falk, Fábián István, Kalmár József, Cserháti Csaba
Department of Solid State Physics, University of Debrecen, Egyetem sqr. 1, H-4032 Debrecen, Hungary.
Doctoral School of Physics, University of Debrecen, Egyetem sqr. 1, H-4032 Debrecen, Hungary.
Polymers (Basel). 2021 Feb 16;13(4):588. doi: 10.3390/polym13040588.
The imaging of non-conducting materials by scanning electron microscopy (SEM) is most often performed after depositing few nanometers thick conductive layers on the samples. It is shown in this work, that even a 5 nm thick sputtered gold layer can dramatically alter the morphology and the surface structure of many different types of aerogels. Silica, polyimide, polyamide, calcium-alginate and cellulose aerogels were imaged in their pristine forms and after gold sputtering utilizing low voltage scanning electron microscopy (LVSEM) in order to reduce charging effects. The morphological features seen in the SEM images of the pristine samples are in excellent agreement with the structural parameters of the aerogels measured by nitrogen adsorption-desorption porosimetry. In contrast, the morphologies of the sputter coated samples are significantly distorted and feature nanostructured gold. These findings point out that extra care should be taken in order to ensure that gold sputtering does not cause morphological artifacts. Otherwise, the application of low voltage scanning electron microscopy even yields high resolution images of pristine non-conducting aerogels.
通过扫描电子显微镜（SEM）对非导电材料进行成像时，通常是在样品上沉积几纳米厚的导电层之后进行。这项工作表明，即使是5纳米厚的溅射金层也会显著改变许多不同类型气凝胶的形态和表面结构。利用低电压扫描电子显微镜（LVSEM）对二氧化硅、聚酰亚胺、聚酰胺、海藻酸钙和纤维素气凝胶的原始形态以及溅射金之后的形态进行成像，以减少充电效应。原始样品的SEM图像中看到的形态特征与通过氮气吸附-脱附孔隙率法测量的气凝胶结构参数非常吻合。相比之下，溅射涂层样品的形态明显扭曲，且具有纳米结构的金。这些发现指出，应格外小心以确保金溅射不会造成形态假象。否则，即使是原始的非导电气凝胶，应用低电压扫描电子显微镜也能得到高分辨率图像。
