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An SEM User’s Guide to Energy Dispersive Spectroscopy

Explore JEOL's Gather-X Windowless EDS: a breakthrough in SEM-EDS technology for unprecedented sensitivity and spatial resolution in elemental analysis.

3 MIN READ

EDS innovations for advanced materials characterization

SEM column and typical EDS spectra
SEM column and typical EDS spectra
Scanning electron microscopy (SEM) is a cornerstone of microscopic analysis. It revolutionized the field by enabling researchers to delve deeper into materials than was previously possible. This was primarily due to its unprecedented resolution, courtesy of the innovative electron beam at the heart of any SEM system. But the power of SEM technologies stretches beyond resolution into sheer versatility. Many companion systems have emerged which continue to push that technological letter. One such system is energy dispersive spectroscopy (EDS).
EDS is a method that significantly expands the analytical capabilities of electron microscopy by facilitating elemental analysis and characterization. This article is an overview of the method suitable for beginners.

Understanding SEM: The Foundation

Firstly, you may benefit from a recap of SEM functionality. The principle of SEM operation revolves around using a focused beam of high-energy electrons that interacts with sample surfaces. This interaction generates various signals, each providing unique and valuable data. An electron gun generates the primary electron beam in SEM; typically employing a tungsten filament or a more refined field emission source for sharper imaging.
The diverse types of signals produced in SEM are crucial for different analytical aspects. Secondary electrons, primarily used for imaging, offer detailed insights into the sample's surface topography and morphology. Backscattered electrons indicate atomic number contrast and are invaluable in understanding the composition and phase distribution within the sample. Characteristic X-rays, which are central to EDS techniques, play a pivotal role in elemental analysis. Additionally, cathodoluminescence, another signal type in SEM, can reveal information about the electronic structure of materials.
An SEM's design includes several key components: the electron source for generating the primary electron beam; electron lenses to focus and direct this beam onto the sample; a sample chamber kept under vacuum where the sample is placed and manipulated; and various detectors that capture the different signals such as secondary electrons, backscattered electrons, and X-rays.

Energy Dispersive Spectroscopy: Expanding SEM’s Horizons

EDS data for cross section of lithium-ion battery
EDS data for cross section of lithium-ion battery
Energy dispersive spectroscopy, often integrated into SEM systems, is a qualitative and quantitative analytical technique for elemental analysis. When the electron beam of the SEM interacts with the sample, it displaces inner-shell electrons, causing the atom to emit characteristic X-rays. EDS detects these X-rays, allowing for the determination of the elemental composition of the analyzed volume.

EDS Components and Operation

  1. Detector: The heart of EDS, typically a Silicon Drift Detector (SDD), is responsible for capturing emitted X-rays.
  2. Pulse Processor: Converts the X-ray signals into a digital spectrum.
  3. Data Analysis Software: Interprets the spectrum, identifying peaks corresponding to specific elements.

Advantages of EDS in SEM:

  1. Non-destructive Analysis: EDS is a non-invasive method that maintains the sample's integrity.
  2. Elemental Mapping: Provides spatial distribution of elements, enhancing the understanding of material composition.
  3. Quantitative Data: Offers quantitative information about the elements present in the sample.

Pioneering SEM-EDS Innovation with Gather-X Windowless EDS

At JEOL, we recognize the importance of advanced analytical capabilities in SEM technologies. This is exemplified by our Gather-X Windowless EDS system, a testament to our commitment to pushing the boundaries of scientific exploration. Specifically designed for JEOL SEMs, Gather-X embodies a leap forward in sensitivity and resolution, especially in detecting low-energy X-rays down to Lithium. This capability is not just an incremental improvement but a significant advancement in elemental analysis. It enables researchers to explore new frontiers in materials science, nanotechnology, and beyond.
SEM image and corresponding EDS analysis of lithium in sample
SEM image and corresponding EDS analysis of lithium in sample
The 100mm² windowless EDS of Gather-X, tailored for our IT800 series FE SEMs, offers an expansive X-ray range collection, including those challenging low-energy X-rays. Its novel racetrack design and integrated controls facilitate collection at working distances as short as 1mm, yielding clear, high-count-rate EDS maps with exceptional spatial resolution. This feature is crucial for detailed material characterization and understanding intricate material properties at the nanoscale.
Gather-X's integration into our SEM Center software with Live Analysis enhances user experience, allowing real-time display of EDS spectra or maps concurrently with SEM imaging. This seamless integration underscores our commitment to delivering user-friendly, high-performance analytical tools. The system's flexibility, demonstrated by its compatibility with multiple JEOL EDS detectors, further amplifies its utility across various research and industrial applications.
With features like a large solid angle for higher count rates and fast collection times, Gather-X minimizes potential beam damage to sensitive specimens. The system's unique electron trap design permits EDS data collection under normal analysis conditions without harming the detector, even at high beam voltages up to 30kV. Moreover, the capacity for short working distance/beam deceleration mode analysis ensures safe operation at close quarters, vital for ultrahigh-resolution SEMs.
In essence, JEOL's Gather-X Windowless EDS, an exclusive design for our SEMs, exemplifies our ethos of blending smart, flexible, and powerful technology. This system not only delivers high sensitivity and spatial resolution for both imaging and analysis but also symbolizes JEOL's dedication to advancing the field of electron microscopy with intelligent and versatile solutions.

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