日本ゼオライト学会　刊行物 Publication of Japan Zeolite Association

Recent progress on scanning electron microscope (SEM) technology has enabled us to observe the porous structure of nanoporous materials in a nanometer scale. The most commonly used method for the direct structural observation of nanoporous materials employs a high-resolution transmission electron microscopy (TEM). However, the TEM images correspond to the projected structures of the specimen because the electrons are accelerated at a high voltage of generally more than 100 kV. In addition, certain pre-treatment processes that may damage the structure of the specimen, such as the use of a focused ion beam (FIB), or ion thinning with Ar ions, are necessary prior to the TEM observation. In contrast, an SEM has advantages over a TEM in terms of ease of sample preparation and the observation of top-surface images with a lower electron acceleration voltage. We can also expect to use SEM to investigate internal porous structures with a cross-section fabrication technique. Very recently, we proposed an HR-SEM observation technique of internal mesostructure in mesoporous silica in combination with a broad ion beam (BIB) method. This paper reports recent results for the direct imaging of the surface and internal structure of mesoporous silica materials using a low acceleration voltage FE-SEM and recently developed techniques.