Depth of information in photoelectron microscopy

Area of Science:

• Materials Science
• Surface Science
• Microscopy

Background:

• Depth of information quantifies subsurface data contribution in microscopy.
• Photoelectron microscopy (PEM) offers surface-sensitive imaging.
• Understanding information depth is crucial for interpreting PEM images.

Purpose of the Study:

• To model the relationship between electron escape depths and information depth in PEM.
• To elucidate how instrument resolution influences the depth of information obtained.
• To explore various information transmission mechanisms in surface microscopy.

Main Methods:

• Utilized a simplified model of photoemission.
• Analyzed the interplay between electron escape depths and instrument resolution.
• Considered information carried by reflected light and induced topography.

Main Results:

• Information depth equals escape depth when escape depth is small relative to resolution.
• Large escape depths or reflected light yield superimposed surface and diffuse subsurface images.
• The depth of information is variable, depending on imaging parameters and signal origin.

Conclusions:

• The depth of information in PEM is not a fixed sample property but is dependent on experimental conditions and signal type.
• PEM can provide both surface-resolved and subsurface information, with the balance controlled by electron escape depth and imaging mode.
• Mechanisms like induced topography also contribute to the information depth, broadening PEM's analytical capabilities.