Sigray XCITE™ for Electron Microscopes
Upgrade your Electron Probe Microanalyzer (EPMA) or SEM
to reach sub-parts per million
The Sigray XCITE-EM™ attachment is an electron microscope or microprobe upgrade that enables unprecedented sensitivity of trace level (low to sub-ppm) at acquisition times of within a single second. The attachment provides a sharply focused, high flux x-ray spot of several microns upon the sample for highly accurate microanalysis.
Advantages of the XCITE-EM™ attachment include:
- Resolution on single digit microns-scale for correlative chemical information with EPMA x-ray microanalysis
- Sub-1-10 ppm sensitivities... acquired fast
- Capabilities for biological and polymeric samples
- Complementary information to EPMA information, including sub-surface elemental information
An overview of how the system benefits an EPMA laboratory and more detailed description of the XCITE EPMA attachment are described below.
How the XCITE™ for EPMA benefits your laboratory
Benefit #1: unprecedented sensitivity within a single second
The XCITE has demonstrated sub-femtogram absolute sensitivity and <1-10 parts per million (ppm) relative detection sensitivity within 1 second. The system's patent-pending x-ray source and x-ray mirror lens designs provides realization of the inherent advantages of the technique, which does not suffer from the bremsstrahlung background encountered in electron excitation.
Shown on the right is the spectra of a nanometers-thick Ti coating on an SiN window measured within 1 second and demontrating sub-femtogram sensitivity. Note that the lack of bremsstrahlung background.
benefit #2: acquire users from biological and polymeric sciences & resolve challenging ultra-trace applications
There are several well-known limitations to electron-based chemical microanalysis, particularly in regards to biological and polymeric samples, which require high sensitivities and are prone to charging, and for ultratrace measurements. An XCITE upgrade would bring new capabilities to existing EM systems to address major challenges, including:
- Acquisition of new user groups (such as biologists and polymeric materials science researchers): Several rapidly emerging topics within biological and polymeric science research require sub-ppm sensitivities. This includes studies on nanoparticle drug delivery and the growing field of metallomics, which studies the link between diseases (e.g. Wilson's, Alzheimer's, autism, cancer, infertility) and the distributions of trace elements within tissues and cells, which can be impacted through nutritional/environmental factors and by dysregulations in biological pathways. Moreover, XCITE is ideal for hydrated biological and polymeric samples, as it requires little to no sample preparation; this enables analysis of samples in their native states and also removes uncertainties introduced from sample preparation.
- Solve problems in ultratrace measurements: Achieving <100 ppm with electron microprobes typically requires extended measurement times and is simply not possible with standard SEMs. XCITE can be used standalone for elements of low concentration (achieving sub-ppm sensitivity within seconds), or to determine points of interest for extended EPMA analysis. This capability can be used to address problems of new or existing users needing higher sensitivity, such as geochronology users interested in ppm-level rare earth elements in magma rock.
benefit #3: provides crucial complementary information
XCITE provides additional information that can be used to boost the use of EM and to provide additional quantification pathways. This stems from several key features of XCITE, including:
- Comparable Resolution: The Sigray XCITE utilizes a breakthrough x-ray optic in combination with an ultrabright x-ray source to provide single digit microns-scale resolution. This is in contrast to conventional X-ray excitation attachments, which are not commonly employed alongside electron-based techniques due to their limited resolution.
- Fast Survey to Identify Points of Interest: The rapid acquisition of XCITE provides both fast large area mapping and higher resolution, ppm-level mapping that can be used to identify regions of interest for electron microprobe mapping or spot analysis.
- Sub-Surface Analysis of Buried and Hidden Elements: The penetration of x-rays provides sub-surface information to discover embedded or buried elements of interest that would otherwise go undetected with EM. This is particularly important for statistics-limited applications, such as precious minerals in mining tailing samples.
XCITE: what is it and how does it work?
The XCITE EPMA attachment produces an ultrabright microbeam of x-rays that is focused onto a single small, microns-scale spot on the sample and housed in a body that can be placed in a free port of an electron microprobe. The focused x-ray microbeam excites the atoms in the sample, producing x-ray fluorescence at trace sensitivities that can range up to 100-1000X compared to electron excitation.
What's different about x-ray excitation versus electron excitation for x-ray fluorescence?
- Low bremsstrahlung background: X-rays do not decelerate upon impact with the sample as electrons do and thus do suffer from significant bremsstrahlung background (which is one primary sensitivity limiter for electron excitation).
Orders of magnitude fewer x-rays required for the same MDL (minimum detection limit): The fluorescence-cross section of each incident x-ray is 10-10^3 larger than those produced by each incident electron (see chart on right). Due to the high x-ray efficiency and the limiting factor of bremsstrahlung for electron-based measurements, the number of x-rays vs electrons required for the same MDL is around 100 to 100,000X fewer.
Significantly reduced sample damage: The energy deposited by charged electron particles can cause evaporation, redistribution of elements, and radiation damage to chemical bonds. X-rays are less ionizing than electrons and orders of magnitude of fewer x-rays are required for the same MDL, thereby reducing the sample damage problems that can occur with electron analysis.
- Deeper penetration: The deeper penetration of x-rays can uncover buried, hidden elements of interest that may otherwise have gone undetected with more surface-level electron analysis.
What's different about the XCITE versus other x-ray systems?
The patented x-ray source and optic in the XCITE enable several advantages:
- Multiple x-ray spectra to optimize performance for each application: Dual energy targets in the source provide user-switchable spectra so that sensitivities for a wide range of elements are maximized. For example, a dual Copper and Tungsten target can provide several characteristic x-ray lines for optimizing analysis of both light metals (Mg, Al, and Si) and transitional metals (Ti, Cr, Fe, Co).
- Dramatically faster acquisition times: 50X brightness over conventional approaches such as Bruker XTRACE
- Highest resolution with a <8 µm achromatic spot
- Large working distances so that space within the EM system is preserved for additional attachments
For additional information, a more detailed comparison of XCITE vs conventional x-ray approaches can be found here.
specifications of the xcite epma attachment
Compatible Systems: The XCITE™ takes advantage of the existing energy dispersive (EDS) and wavelength dispersive (WDS) spectrometers already equipped on your EPMA. It is compatible with existing electron microprobes, such as: CAMECA (SXFive and SXFiveFE) and JEOL (JAMP-9500F, JXA-8530F Hyperprobe, JXA-8320 SuperProbe).
inquire about XCITE for EPMA
Interested in understanding how the XCITE™ will impact your research or application needs? For a more in-depth technical overview, please fill out the following inquiry forms: