The maximum resolution of a scanning electron microscope (SEM) typically falls between 0.5 and 4 nanometers.
Here's a more detailed breakdown:
- Typical Range: As stated in the provided reference, SEM resolution is commonly found within the 0.5 nm to 4 nm range.
- Factors Affecting Resolution: Several factors can influence the achievable resolution of an SEM. These include:
- Electron Beam Size: A smaller electron beam allows for finer scanning and thus higher resolution.
- Electron Wavelength: Shorter wavelengths of the electron beam improve resolution.
- Specimen Characteristics: The properties of the sample being imaged can also limit resolution. For example, charging effects or poor conductivity can degrade image quality and effective resolution.
- Instrument Quality and Settings: The quality of the SEM, its alignment, and chosen operational parameters significantly affect the ultimate resolution obtained.
- Why Not Higher Resolution? While transmission electron microscopes (TEMs) can achieve higher resolutions, SEMs are typically used for surface imaging. The interaction of the electron beam with the sample surface limits the resolution that can be obtained compared to TEM, which shines the beam through the sample. The scattering of electrons from the sample surface, required to generate the SEM image, inherently introduces some blurriness and reduces the theoretical maximum resolution.
In summary, while ideal conditions and advanced techniques can push the resolution closer to 0.5 nm, a more practical and common range for SEM resolution is between 1 and 4 nm.
