X-ray tomography is perhaps the most well-known imaging technique that employs X-rays. However, this form of electromagnetic radiation isn’t exclusive to CT scanners and the medical imaging world. X-rays are also indispensable in the life sciences industry.

First, let’s review the basics. X-rays are defined as having wavelengths of 0.01 to 10 nanometers (nm). Depending on their wavelengths, they are further subdivided into soft and hard X-rays. Hard X-rays have high energy and relatively longer wavelengths of around 0.2 to 0.1 nm, while soft X-rays have lower energy and longer wavelengths of approximately 10 nm.

The shorter wavelengths and higher energy properties hard X-rays exhibit mean they are excellent at penetrating deep inside of solid objects, making them useful for applications such as medical radiography.

On the other hand, soft X-rays are more suitable for applications such as X-ray crystallography, which requires minimal radiation exposure. Soft X-rays are excellent for gathering the molecular and atomic structure of a crystal (i.e., a biological specimen or protein that’s been crystallized).

Furthermore, soft X-ray microscopy has been used to bridge the gap between optical microscopy and electron microscopy. It is often performed at cryogenic temperatures.

X-ray microscopy, specifically, uses electromagnetic radiation found in soft X-rays to produce magnified images of objects that would otherwise be invisible to the human eye.

First, the object is shot with an X-ray beam, and the soft X-ray photons strike the sample. Because X-rays do not reflect or refract, a charged coupled device detector (CCD) or exposed film must be used to pick up the X-rays as they pass through the sample. Then, the collected X-rays are analyzed, and a magnified image is produced.

A significant advantage that X-ray microscopes have over conventional microscopes is that, due to the penetrative properties of X-rays, biological samples can be imaged with minimal preparation and in their natural state.

Additionally, due to their wavelengths being shorter than visible light, X-ray microscopes have higher spatial resolution compared to normal optical microscopes. Magnification is also comparable.