Study of point spread in aberration-corrected high-resolution transmission electron microscopy

TL;DR

This paper investigates how the point spread function in aberration-corrected high-resolution transmission electron microscopy depends on atomic number, sample thickness, and spherical aberration, comparing NCSI and PCSI modes through simulations.

Contribution

It provides a detailed analysis of the relationship between point spread and various imaging parameters, highlighting the advantages of NCSI mode for smaller peak widths.

Findings

NCSI mode yields smaller peak widths than PCSI.

Peak width depends on atomic number, thickness, and spherical aberration.

Simulations demonstrate the conditions favoring NCSI over PCSI.

Abstract

For quantitative electron microscopy high precision position information is necessary so that besides an adequate resolution and sufficiently strong contrast of atoms, small width of peaks which represent atoms in structural images is needed. Size of peak is determined by point spread (PS) of instruments as well as that of atoms when point resolution reach the subangstrom scale and thus PS of instruments is comparable with that of atoms. In this article, relationship between PS with atomic numbers, sample thickness, and spherical aberration coefficients will be studied in both negative Cs imaging (NCSI) and positive Cs imaging (PCSI) modes by means of dynamical image simulation. Through comparing the peak width with different thickness and different values of spherical aberration, NCSI mode is found to be superior to PCSI considering smaller peak width in the structural image.