Wildfire Questions

What is the tilt range of the Wildfire system?

This tilt range is dependent on the pole-piece gap of your TEM. Here is the summary based on the largest pole-piece: Wildfire H/H+: Alpha tilt up to ±30°, Wildfire H+ 3D: Alpha tilt ±70°, Wildfire H+ DT: Alpha & Beta tilt up to ±25°. Contact us for detailed specifications.

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What is the best achievable resolution at elevated temperature?

The resolution of 0.6 Å can routinely be achieved at 1000 °C. The resolution is dependent on your TEM; however, the achievable resolution at elevated temperature will be as good as for your standard TEM holder.

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What is the temperature range for the Wildfire system?

The Wildfire H system allows any temperature between RT to 600 °C. All the other systems enable any temperature between RT and 1100 °C (SiNx support) and 1300 °C (through hole).

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Is Wildfire compatible with EDX?

Due to small heater using only a few mW of power to heat to elevated temperatures, EDX signal can now be obtained at elevated temperatures up to 1000 °C. Performance is dependent on your TEM/EDS setup.

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Can a Wildfire system be used for biasing experiments?

We support customers in upgrading their Wildfire H+ DT systems to perform biasing experiments. This is the Wildfire Biasing Expansion Pack. In the case that the customer develops their own MEMS devices for biasing experiments, the Wildfire holder is able to be used in conjunction with these ‘home-made’ MEMS devices.

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Lightning Questions

What is the size of sample recommended for biasing experiments?

The sample size depends on the type of experiment to be executed. For 4 point probe measurement approach, where all four biasing electrodes need to be bridged, the required sample length is 10-15 microns. In the situation where only two inner electrodes are involved in the experiment (for example, E-field application), the sample size is can be in the order of 4 microns.

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What preparation methods other than FIB could be usable for biasing experiments?

FIB is very important in transferring materials for biasing experiments, especially for lamella’s as it’s the most commonly used method. While for 1D materials (e.g. nanowires) and 2D materials (graphene), the transfer method can vary dependent on what tools you have available such as a micro-manipulator.

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What is the homogeneity of the electrical field?

Designs show that the uniformity of the electric field is as high as 99%.

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What TEM pole-pieces are compatible?

Due to the variety of pole-pieces available for both the JEOL and FEI microscopes, please see the brochure for confirmation. However, the Lightning series is compatible with the smallest pole-pieces found in the JEOL UHR (e.g. ARM) and the FEI Supertwin (e.g. Titan).

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What really sets the 50V / 100V limit?

Two reasons:

  1. To avoid the electric failure between connection pins in the vacuum. (Electric sparks)
  2. To avoid breakdown of SiNx at high electric field (the limit is lower at elevated temperature).

Be aware, the specified voltage is not the breakdown voltage of our system, but in fact to ensure a low leakage current. Therefore, in reality one could go much higher than the specified numbers if the experimental details allow.

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Can my sample survive the electrical loading induced?

Yes. For common samples, such as lamella’s, metallic nanowires, etc., these samples have proved to be safe during loading without any special care needed. As for sensitive semiconducting nanodevices, grounding connections through source measuring unit / power supply (e.g. Keithley) are needed to make sure there is no static voltage drop over nanodevices, therefore, preventing any damage of high current to the sample.

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Climate Questions

Is the Climate compatible with EDS and EELS?

Yes, EELS has proven to produce very good spectra even at pressures as high as 1 Bar. The primary electron beam from a TEM will have minimal interaction with the Nano-Reactor windows or the small quantity of gas inside. Moreover, the newly introduced tip and Nanoreactor allow collection of high quality EDS spectra and maps at tilt angles up to 30 degrees (for S-TWIN lens).

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What is the preparation time for a typical experiment?

Preparing the system to run an experiment would typically take less than 30 minutes:

  1. 5 minutes to load the sample on the Nano-Reactor (e.g. drop casting method and let the ethanol drop evaporate)
  2. 10 minutes to assemble the tip: placing the Nano-Reactor and closing off the lid
  3. 3 minutes to align the top chip membrane around the heater spiral on the bottom chip
  4. 10 minutes to do the electrical connection and leak test (pump down time taking most this time)

This time does not include sample preparation as this can vary from sample to sample.

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What type of samples can be used inside the Climate Nano-Reactor?

The typical samples used are nanoparticles for catalyst research which can be drop cast using a small (<=2 μL) pipette to deposit directly onto the electron transparent window. Nanowires and thin lamellas can be loaded onto the Nano-Reactor using tweezers and/or micro-manipulators. In general, any sample that is less than 6 um (viewing area, the area heated at maximum temperature is about 100 um) in diameter and less than 5 um in height can be loaded into the Nano-Reactor for TEM imaging.

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What gases can be used in the Climate system?

The list of permitted gases is determined based on if that particular gas will interact with the materials used in the Nano-Reactor, Sample Holder and Gas Supply System. The materials in which the gas will be in contact with include:

  1. Silicon Nitride – Nano-Reactor’s window material
  2. Stainless Steel – Gas inlet lines, mass flow controllers, pressure gauges, control and mixing valves, pumps
  3. PEEK tubing – Fine tubing between Flow Control Unit and Sample Holder
  4. Fused Silica – Components in the Sample Holder
  5. Titanium – Sample Holder tip and lid
  6. Viton – Valve and controller seals in the Gas Supply System and O-rings sealing the Nano-Reactor

Any gases that can react with the above materials at room temperature (or at elevated temperatures for Silicon Nitride) should be avoided. If these gases are critical to your experiment, it is possible to dilute them to a safe level, however, this should be in consultation with DENSsolutions. Alternative materials for some components are possible, please contact DENSsolutions to discuss – e.g. Viton can be replaced by Kalrez. The mass flow controllers at the gas input lines of the Gas Supply System are calibrated for CxHy, O2, H2, N2, He, Ar, CO, CO2, Air. To know the exact gases that can be used, please refer to the chemical resistance sheet. For toxic gases the user will need to install additional safety features to monitor the concentration of that gas inside the lab room.

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Is it necessary to use the Climate Gas-flow Supply System?

DENSsolutions strongly recommends the use of the Climate Gas Supply System that require gas mixing and/or flow. The Climate Gas Supply System has been built specifically for the Nano-Reactor, which ensure the utmost in safety and performance. The Climate G and G+ comes standard with a Gas Supply System. If only static gas experiments where a gas flow is not needed, the Climate AIR system allows the Climate to work in atmospheric conditions, enabling the study of corrosion under real conditions. In all the versions, manual valves ensure the holder can be moved and kept at desired conditions without being connected to the GSS. It is possible to connect your own gas supply system to the Climate Sample Holder, however, DENSsolutions cannot take responsibility for the safe operation of the Climate system.

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How long would it take to replace the gas tubing?

Replacing the tubing would take approximately 10-15 minutes. Fused Silica is the standard material but this can be changed for PEEK or another material if required by the user. Experienced users of the Climate holder will be able to change in ~ 5 minutes.

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Can I safely use the Climate holder in my TEM?

Yes. The Climate system workflow dictates that after assembly of the holder tip but before insertion into the TEM goniometer, the Climate holder is tested for vacuum leaks. Only after this test is passed successfully, the user can continue to the next step (TEM insertion). The Climate holder dimensions are designed within the specifications for the applicable Objective Lens pole piece as provided by the TEM manufacturer (Thermo Fisher Scientific or JEOL). As long as the holder is also used within the Z- and T-axis range as specified in the user manual there will be no danger of a collision between holder and pole piece.

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Will the use of the Nano-Reactor have an impact on the analytical results?

The largest effect will be from the heater Nano-Chip, that will produce mainly Si peaks in the EDS or EELS spectrum, in particular when the electron beam is close to the edge of a transparent window (6 µm diameter). Acquiring a background spectrum by using the Nano-Reactor with gas but without a sample can help in highlighting the specific sample related results in your spectra and maps. In theory some scattering will occur on the electrons passing through the Nano-Reactor. Given the energy of the primary beam (usually 200 or 300 keV) and the low density of the gas and the window there will only be a minor effect.

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What is the tilt range?

Currently, thanks to the newly designed tip and chips, it is possible ti tilt up to ±30 degrees (for FEI/TSF with an S-TWIN objective lens and +/- 25 degrees for JEOL with an WGP objective lens), depending on microscope setup.

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