Overview
The J105 can be equipped with a range of ion beams for analysis, including a 40 kV C60, 40 or 70 kV gas cluster beams, and a 25 kV gold cluster beam, making it the ideal solution for a wide range of materials analysis. Cluster beams enable the analysis of organic material without fragmentation, revealing molecular signals as high as 3,000 Da with good sensitivity.
The analyser is a dual-focussing combination of a shaped-field buncher and a non-linear reflectron that provides sub 5 ppm mass accuracy as well as MS-MS operation. The unique features of the J105 combine to make it ideal for the analysis of topographic samples, maintaining consistent mass calibration and mass accuracy across samples that vary in height by hundreds of microns.
With cold sample handling, an in-situ freeze-fracture system to facilitate analysis of frozen hydrated or freeze-dried samples, and a glove box for handling air sensitive samples, the J105 provides you with the tools to analyse more samples than ever before.
J105 Design Principle
The J105 SIMS is a new concept in SIMS Instrumentation, chiefly designed so that analysis could be performed using different types of ion beams on a range of sample types. By separating mass analysis from the action of the primary beam at the sample, the J105 avoids trade-offs between mass and spatial resolution and rate of acquisition.
J105 SIMS ToF Operation
The J105 operates without the need for fast pulsing of the primary ion beams to perform ToF-SIMS. Instead, it uses a unique dual-focussing time-of-flight mass analyser consisting of a shaped-field buncher and a non-linear reflectron. The buncher takes a slice of collision-cooled secondary ions and compresses them to create a time-focus. A non-linear reflectron is placed after the buncher to give a second time-of-flight stage. The design has many benefits over a conventional ToF – as the mass spectrometer is completely decoupled from both the primary beam and the sample, both mass-resolution and mass-accuracy are independent of primary beam or sample type – giving you consistent performance across all samples and types of primary beam.
Schematic of the Buncher-ToF design used in the J105 SIMS
An Analysis Beam for Every Occasion
The J105 SIMS does not depend on fast pulsing of primary ion beams to provide a time reference, therefore any beam on the instrument may be used for analysis without compromising performance. Additionally, each beam can be used at its optimum DC spot-size, so there is no compromise between mass-resolution and spatial-resolution.
Up to 3 primary beams may be included on the chamber. The choice includes gold, C60, gas cluster, and duoplasmatron beams – each suited to a particular sample type or experiment, as laid out below.
| BEAM | ENERGY | SPOT SIZE | |
|---|---|---|---|
| Gold | 25 kV | < 150 nm | Highest spatial resolution, causes significant fragmentation. Ideal for hard materials. |
| C60 | 40 kV | < 300 nm | Uniform sputtering on any material, low fragmentation, ideal up to 1 kDa. |
| Gas Cluster (Ar/CO2/H2O) | 40 or 70 kV | < 1 μm | High sputter yield on organics, lowest fragmentation of any beam, ideal for bio-imaging. |
| Duoplasmatron (Ar/O2/N2/Cs) | 30 kV | < 300 nm | High brightness source, ideal for inorganic materials. O2 beam enhances positive ion yield, while Cs enhances negative ion yield. |
Mass Calibration & Accuracy
On the J105, the mass calibration and mass accuracy are a function of the Mass Spectrometer only and not altered by the sample or the primary ion beam. This means that changes in sample height or charge state do not alter the calibration or the mass accuracy, which is not the case with other ToF instruments. This ability makes the analysis of large samples, highly structured samples and charging samples very much more straightforward with the J105.
The image below shows an overlay of four masses at a nominal mass of 297. The sample is a set of 12 pairs of bacterial droplets on silicon, all of the same bacteria, but each pair grown under different conditions. Without the ability to maintain the mass calibration to 5 ppm accuracy across the whole sample regardless of height changes, the distribution of the four components in the image below would start to merge together.
Sample area analysed was 2200 μm x 2200 μm.
Extended Mass Range
Conventional primary beams such as Bi3 cause significant fragmentation of surface molecules upon impact, have a usable mass range up to approximately 500 Da, and produce a complex spectrum of fragments to analyse. For many experiments however, the species of interest lie far beyond this. Cluster beams such as C60 and large gas clusters cause far less fragmentation, extending this usable mass range up to 3,000 Da. As the primary beam is optimized for imaging, the J105 SIMS is uniquely placed to exploit the suppier properties of these cluster beams, combining high-resolution imaging with mass spectrometry of high-mass molecular species.
SIMS spectrum from brain tissue sample analysed with a 30 kV (CO2)3000 gas cluster beam. Cardiolipin and ganglioside species are identified beyond m/z 2,000.
High-mass Imaging SIMS
In the J105 SIMS, there is no distinction between imaging-mode and analysis mode – the beam is always optimized for imaging, and every pixel acquired contains a complete spectrum. The main variable is the choice of primary beam, which ultimately determines the limits of lateral resolving power and the observable mass-range of the experiment.
With the GCIB SM, we have extended the lateral resolving power of gas cluster beams down to 1 μm, enabling species such as lipids, gangliosides, and many other metabolically important molecules to be spatially located at higher resolution than ever before!
High-resolution Lipid Mapping. SIMS overlay image of untreated hippocampus tissue showing the spatial distribution of ganglioside and sulfatide species (GM1(38:1), GM1(36:1), and ST(18:0), at m/z 1572.9, 1544.8, and 806.5 respectively). taken at 2 μm per pixel using a 30 keV (CO2)3000 beam. Data courtesy of Hua Tian.
Depth Profiling
The J105 SIMS is ideally suited to depth profiling of samples. An important aspect of using a DC beam for analysis is that there is no need to interlace an etching beam with the analysis beam. To enable 3D image generation on a reasonable time scale, and to remove the damaged sub-surface layers, a conventional ToF experiment uses interlaced imaging and etching cycles that waste precious sample. With the use of a continous analysis beam such as C60 or (CO2)n/Arn on the J105, analysis and low-damage etching are continuous and concurrent, so no data is lost, and all the material is sampled, making the J105 SIMS an extremely accurate tool for depth profile analysis.
In a recent interlaboratory VAMAS study led by NPL, the J105 SIMS demonstrated the highest depth resolution of any instrument on an organic stack structure of Irganox 1010 and Irganox 1098, demonstrating a depth resolution of 12.8 nm.
Depth profile of a stacked Irganox 1010 / Irganox 1098 sample, part of an interlaboratory VAMAS study led by NPL. The J105 SIMS achieved a depth resolution of 12.8 nm – the highest of any instrument.
To read more about Depth Profiling with the J105 SIMS, read our Application Note.
Analysing samples with difficult topography
In the J105 SIMS, mass calibration is not dependent on sample height. Because mass resolution is not affected by conditions in the extraction region, the extraction optics are optimised for efficient collection, even when the sample surface is angled.
(left) Total ion image from an M1.6 screw thread. (right) Comparison of Cr peak (nominal mass 51.94051 Da) from spectra obtained at various locations across the screw thread sample (height variation > 300 µm). Consistent mass accuracy of < 5 ppm is maintained across the sample, independent of sample topography.[/caption] The figure below shows the value of this on a large, curved sample such as an M1.6 screw thread. Using a Au3 beam, there is consistent collection of secondary ions from all areas of this complex surface, with mass-resolution and mass-accuracy independent of the topography. With Au3 , a spatial resolution of 200 nm was achieved with this sample.MS/MS Analysis
Sometimes mass-accuracy and mass-resolution are not enough to identify a particular peak of interest. In this case, MS/MS analysis can be used to select the mass of interest and fragment it, producing a characteristic mass spectrum. This mode of operation is directly built into the J105 SIMS dual-stage analyser. By injecting gas into the flight tube approaching the first focus, stable molecular ions – selected by a timed ion gate – are fragmented by collision induced dissociation (CID), producing a characteristic MS/MS for that species.
MS/MS analysis of a compound at m/z 272, detected during SIMS imaging of Pseudomonas aeruginosa bacteria. Signature peaks at m/z 159 and 172 confirmed the substance as a 4-hydroxy-2-alkylquinoline (HAQ).
The figure below an MS/MS spectrum showing the fragment signature of an extracellular messenger molecule (a HAQ) produced by Pseudomonas aeruginosa bacteria. The availability of MS/MS and the reliable mass accuracy of the J105 SIMS enable identification of unknown organic species.
Versatile Sample Handling with Temperature & Atmospheric Control
The versatile sample handling system on the J105 SIMS enables a wide range of sample types to be analysed. The instrument is equipped with liquid nitrogen cooling to allow analysis of volatile samples – the cooling is applied both to the main sample stage and at the sample insertion lock. Conversely the sample stage may also be heated up to 600 K.
The instrument is fitted with a glove box for preparation and insertion under dry gas, for air/water sensitive samples and the prevention of ice formation during cooling. Sample insertion is quick thanks to a small-volume load lock and high pumping speeds.
“Mousetrap” device for freeze-fracture of samples in vacuum.
A cold-sample fracture “mousetrap” device is available for sample fracture under vacuum and cooling. A sample of liquid suspension can be trapped between two faces of a metal hinge. Once frozen, the assembly can be transferred to vacuum under cooling, and once under vacuum, the device is triggered to open and present two clean, unfrosted, fractured surfaces for analysis.
| DC Cluster Beam SIMS | Reveal large intact molecular species with high signal rates and shorter acquisition times. |
| Consistent Mass Accuracy and Mass Resolution | Mass spectrometer performance is independent of primary beam, sample height, and sample charging effects |
| Wide Range of Primary Beams | Choose from up to three different primary beams, including Liquid Metal, C60, and Gas Cluster Beams, each with a integrated mass filters. |
| Unique ToF Design | Unique Buncher-ToF decouples mass spectrometer from the primary beam for consistent mass-resolution and mass-accuracy independent of sample type, sample environment, and choice of primary beam. |
| Dynamic stage control | 3-axis (X,Y,Z) precision sample stage |
| Versatile Sample Handling with Atmospheric Control | Sample handling system comes complete with a load lock for fast pumping, the ability to load up to three sample holders at a time, and glove box for air-sensitive samples. Fully integrated cryogenic sample handling. Wide temperature range of 100 – 600 K on stage, biasable up to ± 100 V |
| Charge Compensation | >10 eV – 1 keV electron flood gun |
| Tandem MS | MS/MS capabilities with integrated mass filter and collision cell. |
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