XAS Spectroscopy System
First laboratory XAS system with both transmission and fluorescence mode XAS
- Only laboratory XAS system with synchrotron-like performance
XANES at 0.5 eV and EXAFS within seconds
- Fluorescence mode XAS
First laboratory fluorescence XAS, enabling XAS analysis of low concentration samples
- Energy range from 4.5 keV to 25 keV
Range encompasses transition metals such as titanium and platinum… to lanthanides
Synchrotron-like Performance in a Laboratory XAS System
X-ray absorption spectroscopy (XAS) generates the most publications of any synchrotron approach. Because of the technique’s popularity, XAS beamtime can be challenging to acquire, requiring in some cases lengthy proposal submission and evaluation periods. The competitive nature of oversubscribed beamlines mean that even highly meritorious projects rejected. Sigray developed the QuantumLeap products to make it easy to access synchrotron-like XAS performance within your own laboratory, making it possible to complete research otherwise not possible, including those involving many samples or complex in-situ experiments.
Fluorescence-mode XAS for Low Concentration Samples
X-ray absorption spectroscopy (XAS) is measured by the amount of x-rays absorbed by the sample near the absorption edge energy of an element of interest. At this resonance energy, slight differences in x-ray absorption are attributable to differences in the electronic structure (e.g., oxidation state and bond lengths). The most direct way to measure XAS is in transmission-mode, in which the number of x-rays transmitted through the sample is used to determine how absorbing the sample is to the x-ray energy. An indirect method is fluorescence-mode. Due to the absorption of x-rays, the electrons of atoms of interest are excited. Upon relaxation, fluorescence photons are produced. The total intensity of fluorescence photons is determined by how many x-rays were originally absorbed.
Both transmission and fluorescence modes of XAS produce the same spectral graphs. The difference is that fluorescence mode is superior for low concentration (<3-5%) samples while transmission mode is superior for bulk samples. Additionally, fluorescence mode XAS can be performed on thicker samples.
Energy Range from 4.5 to 25 keV
QuantumLeap is the only laboratory system capable of operating at low Bragg angles, which enables acquisition of a complete EXAFS from a single crystal, without requiring stitching together multiple datasets. In comparison, systems operating with high Bragg angles (e.g., 55 degrees to near-backscatter at 85 degrees) require multiple crystal analyzers to maintain adequate resolution. Operating at a high 85 degree Bragg angle can provide high energy resolution, but comes with major drawbacks for usability. For instance, a crystal rotation of 1 degree will only cover 7 eV at 4.5 keV and 39 eV at 25 keV. The same crystal can be used for the entire EXAFS range only if energy resolution is severely sacrificed. Otherwise, adequate energy resolution requires a very large number of crystal analyzers to cover a 1000 to 2000 eV bandwidth of EXAFS. Use of many crystals is disadvantageous because it does not allow for straightforward robotic exchange of crystals (instead, manual changing of crystals is required that severely slows down acquisition time) and because each acquisition must be stitched and aligned.
- Patented high brightness x-ray source with multiple targets, enabling high throughput in the laboratory and acquisition of the full range of elements
- Photon counting detector for high flux measurements
- Intuitive software for acquisition and analysis. Can output data in CVS files to be read by software such as Athena and Artemis
Patented Multi-Target Ultrahigh Brightness X-ray Source
The QuantumLeap’s x-ray source features a patented design in which multiple target materials are in optimal thermal contact with diamond, which has excellent thermal conductivity properties. The rapid cooling of diamond enables higher power loading on the x-ray source to produce an intense beams of x-rays. Another key feature of the x-ray source is its motorized x-ray multi-material target, which allows software selection between more than one x-ray target material. This is important for XAS acquisition because switching between target materials allows avoidance of the strong characteristic x-ray energies for a given material that would otherwise contaminate the results.
Photon Counting Detector in Transmission Mode
QuantumLeap-H2000 uses a patented transmission XAS acquisition approach in which a novel photon counting detector is used to acquire the XAS spectrum instead of a conventional silicon drift detector (SDD). These detectors have extremely fast readout speeds to detect each photon individually, enabling energy thresholding to remove harmonic contamination. Using these detectors instead of SDDs enables count rates of up to 10^8 (100 million) counts per second – more than 500X that of SDDs; SDDs are limited to half a million counts per second. Such detectors are necessary for the transmission mode of XAS QuantumLeap due to the high flux incident upon the sample. For fluorescence mode XAS, QuantumLeap-H2000 uses an SDD detector.
QuantumLeap features an intuitive GUI for acquiring data, including the capability to set up recipe-based scans for point-by-point mapping or for multiple samples (a sample holder for up to 16 samples of 3″ diameters is provided). Data can be output as CSV files that can be easily read into analytical software, including Athena and Artemis.
Catalysts, which are used to speed up chemical reactions, are estimated to be used in 90% of all commercially produced chemical products and represent more than a $30B global market. They are used in a vast array of applications, spanning from polymers, food science, petroleum, energy processing, and fine chemicals. Synchrotron-based XAS has become the method of choice for developing novel catalysts and to link structural motifs with catalytic properties. QuantumLeap provides convenient in-laboratory access to such capabilities without requiring the time and expense of acquiring synchrotron beamtime.
Batteries and Fuel Cells
There are a very large number of potential electrode hosts for Li+ being explored in lithium ion batteries (LIBs), including different material compositions and various structures (micro to nanosized). XAS is commonly used to characterize structural and electronic information of electrodes to obtain understanding of electrochemical mechanisms governing a given battery’s chemistry. Sigray’s QuantumLeap not only enables ex-situ determination of electrocatalyst chemistry, but is also designed with baffles and feedthroughs for optional in-situ cells to study changes in-operando.
Nanoparticles and Nanotubes
The electric, magnetic, and catalytic properties of nanoparticles differ strongly from the same materials in bulk phase. These properties depend on the nanoparticle’s size and shape. Nanoparticles of 1-5nm in size are difficult to characterize with ordinary laboratory techniques such as XRD and TEM. XAS provides information on the distance of atoms, average size of particles smaller than 2nm, and even shape.
Technical Specifications of the QuantumLeap-H2000
|Overall||Energy Coverage||4.5 to 25 keV|
|XAS Acquisition||Transmission mode
|Energy Resolution||Sub-eV in XANES
5-10 eV in EXAFS
(Note that you can also use XANES mode to acquire high resolution EXAFS)
|Beam Path||Helium flight path|
|Focus at Sample||Line focus: 30-100 μm in one direction; ~300 um - 3mm in other direction|
|Source||Type||Sigray patented ultrahigh brightness sealed microfocus source|
|Target(s)||W and Mo standard.
Others available upon request.
|Power | Voltage||300W | 20-50 kVp|
|X-ray Crystals||Type||2 Johansson single crystals
1 mosaic crystal
|X-ray Detector(s)||Type(s)||Spatially resolving (pixelated detector) for transmission XAS
Silicon drift detector (SDD) for fluorescence XAS
|Count Rate||10^8 x-rays/s for photon counting detector
500k cps for SDD
|Dimensions||Footprint||53" W x 77" H x 66" D|
QuantumLeap is designed with feedthroughs and baffles for flexibility in designing and executing in-situ and in-operando experiments. We currently offer an off-the-shelf design for in-situ with the following capabilities:
- Vacuum-compatible sample chamber reaching 10^-7 Torr
- Gate valve for load lock mechanism
- Fluid feedthroughs for Argon and O2
- Feedthroughs for electrical, power, and heating
Interested in how the Sigray QuantumLeap™ will help your particular application? Trying to figure out which model better suits your needs?
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