Where are the limits to spatial resolution in the HRTEM?

Abstract

In discussing resolution limits, it is important to distinguish between the resolution of a microscope and the resolutions of the images produced by the microscope. The spatial resolution of a high-resolution transmission electron microscope (HRTEM) is an upper bound on the resolution of images that can be produced by that microscope, but there is no guarantee that any particular image from the microscope will attain this bound. In addition to instrumental limits, properties of the specimen will act to degrade image resolutions. For specimens that beam-damage rapidly, image resolution depends upon electron energy and electron dose. For small-cell crystalline specimens, Bragg's law mandates that allowable resolutions be quantized, preventing image resolution from reaching microscope resolution. However, improving the resolution of a HRTEM gives it the capability to produce higher resolution images.Image “resolution” is a measure of the spatial frequencies transferred from the image amplitude spectrum (specimen exit-surface wavefunction) into the image intensity spectrum (Fourier transform of the image intensity).