Nanos tabletop SEM with integrated EDS Analysis: Adding Chemical Insight to Electron Microscopy

EDS stands for Energy Dispersive X-ray Spectroscopy. It is an analytical technique used together with SEM to identify the chemical elements present in a sample.

During analysis, the electron beam of the SEM interacts with the atoms in the material. This interaction generates different signals, each carrying different types of information. Secondary electrons are mainly used to reveal surface morphology and shape, while backscattered electrons can highlight contrast related to atomic number and material composition. Characteristic X-rays, generated from the interaction volume within the sample, are the signals used by EDS for elemental analysis.

The origin of these X-rays is linked to the atomic structure of the elements in the sample. When the primary electron beam interacts with an atom, it can disturb electrons in the inner shells. As the atom returns to a more stable state, energy is released in the form of an X-ray. The energy of this X-ray is characteristic of the element that produced it, which is why EDS can be used to identify chemical composition.

These X-ray signals are collected by the EDS detector and converted into a spectrum. By reading this spectrum, it is possible to identify the elements present and, in some cases, evaluate their distribution or relative concentration.

In simple terms, while a compact SEM allows users to observe the morphology of a sample, EDS adds another essential layer of information: chemical composition.

EDS spectra

An EDS spectrum is one of the core outputs of SEM-EDS analysis. It displays the X-ray signals collected from the analyzed area, with peaks corresponding to the elements detected in the sample. Each peak is linked to a characteristic X-ray energy, allowing the software to identify which elements are present.

Beyond simple identification, the spectrum can also support quantitative or semi-quantitative evaluation, helping users estimate the relative amount of each element in the analyzed area. This makes spectra an important first step for understanding the chemical composition of a material, confirming the presence of specific elements, or investigating unexpected contamination.

Point and area analysis

Point and area analysis allows users to select a specific point or region on the SEM image and identify its elemental composition. It is useful for analyzing inclusions, particles, contamination, localized defects, or specific areas of interest.

This workflow is particularly valuable when a feature visible in the SEM image needs to be identified chemically. For example, a small particle, a bright inclusion, or an unexpected deposit can be selected and analyzed to understand which elements are present.

Line scans

A line scan shows how elemental composition changes along a selected line on the SEM image. The operator draws a line across a feature of interest — for example an interface, a particle, a coating, a layered structure, or a transition between two different phases — and the EDS software displays how the detected elements vary along that path.

This workflow is especially useful for studying interfaces, coatings, layers, joints, diffusion zones, inclusions, and transitions between different materials. It helps users understand not only which elements are present, but also how their distribution changes from one region to another.

Elemental mapping

EDS mapping, also known as region mapping, shows how chemical elements are distributed across a selected area of the sample. Instead of analyzing only one point or one line, the operator selects a region of interest and the software generates individual elemental maps, as well as a combined map where different elements can be displayed with different colors.

This workflow is particularly useful for comparing different regions, checking material homogeneity, identifying phases, detecting contamination, and understanding how elements are distributed within complex microstructures. When the elemental map is compared or overlaid with the SEM or BSD image, it becomes easier to connect what is visible in the image with the chemical composition of each area.

For example, particles, inclusions, coatings, grains, or different phases that appear with different contrast in the SEM image can be investigated chemically, helping users understand whether visual differences also correspond to compositional differences.

The quality of EDS data depends not only on the detector, but also on correct SEM configuration. In the case of the Semplor Nanos compact SEM, the Nanos EDS detector and the proper instrument setup play an important role in obtaining reliable analytical results.

One of the key factors in SEM-EDS analysis is geometry. For efficient X-ray collection, the sample should be positioned correctly in relation to the electron beam and the EDS detector. In practical terms, this means working with the appropriate working distance, keeping the sample as flat as possible, and avoiding unnecessary stage tilt during EDS acquisition.

A specific advantage of the Semplor Nanos tabletop SEM is its single working distance of 10 mm. This allows users to acquire excellent SEM images and collect EDS data at the same working distance, simplifying the workflow and helping maintain the proper geometry for efficient X-ray collection.

Another important parameter is the accelerating voltage. The primary electron beam does not interact only with the surface, but with a volume of material beneath it. The depth and size of this interaction volume depend on the accelerating voltage and on the atomic number or weight of the sample. Higher accelerating voltages generally increase beam penetration and may generate X-rays from a larger volume of material.

This means that SEM-EDS analysis is not only about detecting which elements are present, but also about understanding where the signal is coming from. Choosing the right conditions helps obtain data that is more representative of the area of interest.

Parameters such as working distance, sample geometry, accelerating voltage, material type, and sample preparation can significantly influence the result. A proper setup helps generate more reliable spectra, clearer elemental maps, and more accurate interpretation. On the other hand, non-optimized settings may produce data that is harder to read or may lead to incorrect conclusions.

Some peaks in the spectrum may be caused by artifacts rather than by elements actually present in the analyzed area. For example, sum peaks can occur when two X-rays reach the detector almost simultaneously and are recorded as a single event with an energy equal to the sum of the two incoming X-rays. As a result, an additional peak may appear in the spectrum, even though it does not necessarily correspond to a real element in the sample.

Another example is the presence of escape peaks. These can occur inside the detector when part of the incoming X-ray energy is not fully collected, producing a smaller peak at a lower energy than the original signal. If not recognized, this type of artifact can also complicate spectrum interpretation.

This is why experience, correct setup, and suitable software tools are essential for reliable SEM-EDS analysis. Recognizing limitations, selecting the appropriate detector configuration, and understanding spectrum artifacts help avoid misinterpretation and support more accurate conclusions about the sample composition.

To obtain useful and reliable EDS data, several factors should be considered. Sample position and geometry are essential: a flat sample, properly positioned at the correct working distance, helps improve X-ray collection efficiency and data quality.

It is also important to remember that X-rays can be generated from a volume of material that may extend over a region of several microns, depending on the material and beam settings. This means that EDS results must always be interpreted in relation to the size of the feature being analyzed and the interaction volume of the electron beam.

Correct beam settings are another important part of the workflow. The goal is to choose conditions that provide the chemical information needed while maintaining stable and efficient acquisition. In practice, this means balancing image quality, X-ray signal, acquisition speed, and analytical accuracy.

Spectrum interpretation also requires attention. Artifacts such as sum peaks and escape peaks can appear in the spectrum and may affect the identification of elements if they are not recognized correctly. For this reason, EDS analysis benefits from both suitable software tools and proper analytical know-how.

For elemental maps, acquisition conditions influence the level of detail and reliability of the result. Live EDS maps are useful for obtaining a quick overview of elemental distribution, while higher-quality map acquisitions can be used when more detailed chemical information is required.

Finally, for applications involving light elements such as nitrogen, the detector window configuration becomes especially important. An ultra-thin EDS window can improve low-energy X-ray transmission, making it a valuable option for laboratories interested in nitrogen analysis or other light-element applications.