Low-dose high-resolution EM of zeolite materials with slow A scan CCD camera

Abstract

Zeolite materials are widely used as an important type of catalyst in oil industry. Their catalytic properties and performance are closely related to their unique structures. Use of high resolution electron microscopy (HREM) to characterize structures of zeolite materials has been limited mainly due to the great sensitivity of the framework structures to electron beam irradiation used in the observation. With the recent development in solid state electronics, a new type of image recording device, known as a charge-coupled-device (CCD), has been made possible. Among many of its superior properties, it has been found that the very low noise level present in a slow scan CCD camera offers the possibility of recording high resolution structure images of zeolite materials with very low electron beam dose. The digital storage of CCD images allows on-line image processing to be performed at the microscope, thus making the recording of low dose electron microscope images more efficient. Image processing was also found to be essential in extracting high resolution structure information contained in the noisy low dose HREM CCD images.