Spectra 300 TEM

The Spectra 300 (S)TEM can be optionally equipped with either a high-energy-resolution extreme field emission gun (X-FEG)/Mono or an ultra-high-energy resolution X-FEG/UltiMono. The monochromators of both sources are automatically excited and tuned with single-click operation to achieve the highest energy resolution possible on each configuration by using OptiMono or OptiMono+ respectively (see video below).

The X-FEG/Mono can be automatically tuned from 1 eV down to 0.2 eV, while the X-FEG/UltiMono can be automatically tuned from 1 eV down to <30 meV.

Both sources can be operated from 30 – 300 kV to accommodate the widest range of specimens. Both can also be run in standard mode, with the monochromators switched off, to accommodate experiments that require high brightness, including STEM EDS mapping, ultra-high-resolution STEM, or high total current, such as TEM imaging, all with no compromise to the other specifications of the system. This flexibility gives the Spectra 300 (S)TEM the capability to function in settings where a large range of experiments are expected to be performed on one system.

The Spectra 300 (S)TEM can optionally be powered by a new cold field emission gun (X-CFEG). The X-CFEG has extremely high brightness (>>1.0 x 10⁸ A/m²/Sr/V*), low energy spread (<0.4 eV), and can operate from 30 – 300 kV. This provides simultaneously high-resolution STEM imaging with high probe currents for high throughput, fast acquisition STEM analytics in parallel with high-energy resolution. With the powerful combination of X-CFEG and the S-CORR probe aberration corrector, sub-Angstrom (<0.8 Å) STEM-imaging resolution with over 1000 pA of probe current can be routinely achieved.

Further, probe currents can be flexibly tuned from <1 pA up to the nA range with fine control of the gun and condenser optics, all with minimum impact on the probe aberrations, so that the widest range of specimens and experiments can be accommodated.

As with all cold field emission sources, the sharp tip requires a periodic regeneration (called flashing) to maintain the probe current. With the X-CFEG, the tip only requires flashing once per working day, a process takes less than a minute. There is no measurable impact on the probe aberrations even in the highest resolution imaging conditions, and the daily tip flashing process has no impact on the tip lifetime.

Tip flashing on the X-CFEG: 60 pm resolution at 200 kV is maintained before and after tip flashing without adjustment of the optics. The process takes <1 min, is required only once per working day, and has no impact on the lifetime of the tip.

This new generation X-CFEG also produces enough total beam current (>14 nA) to support standard TEM imaging experiments (e.g. in situ) with large parallel probes, making it a uniquely all-purpose, yet high performance, C-FEG.

Adding to the flexible nature of the X-CFEG is the capability to adjust the energy resolution by varying the extraction voltage.

In the example below, the energy resolution was adjusted between 0.39eV, with <500pA of probe current and 0.31eV, with >300pA of probe current. Maintaining high probe currents with high energy resolution allows for detailed analysis of Energy Loss Near Edge Structure (ELNES) analysis without the need for a monochromator on core loss edges. The spatial resolution, as demonstrated in the HAADF image of DyScO₃, remains unaffected (in this case <63pA) which means that STEM EELS experiments with simultaneously high spatial resolution, energy resolution and signal to noise ratio can now be performed.

The lifetime of the tip is unaffected by the extraction voltage chosen to perform the experiment.

The combination of enhanced mechanical stability, the latest 5^th-order probe aberration correction and the high-resolution (S-TWIN) wide-gap pole piece results in an instrument with the highest commercially-available STEM resolution specifications.

The Spectra 300 (S)TEM, with X-FEG/Mono or X-FEG/UltiMono, offers STEM resolution specifications of 50 pm at 300 kV, 96 pm at 60 kV and 125 pm at 30 kV with 30 pA of probe current or 100 pA with the X-CFEG.

For a full list of specifications, please refer to the  Spectra 300 (S)TEM datasheet.

STEM imaging on the Spectra (S)TEM has been reimagined with the Panther STEM detection system, which includes a new data acquisition architecture and two new, solid state, eight-segment ring and disk STEM detectors (16 segments in total). The new detector geometry offers access to advanced STEM imaging capability combined with the sensitivity to measure single electrons.

The entire signal chain is optimized and tuned to provide unprecedented signal-to-noise imaging capability with extremely low doses to facilitate imaging of beam sensitive materials. Additionally, the completely redeveloped data acquisition infrastructure can combine different individual detector segments, with the future possibility of combining detector segments in arbitrary ways, generating new STEM imaging methods and revealing information that is not present in conventional STEM techniques. The architecture is also scalable and provides an interface to synchronize multiple STEM and spectroscopic signals.

The Spectra 300 (S)TEM can be configured with an electron microscope pixel array detector (EMPAD) or a Thermo Scientific Ceta Camera with speed enhancement to collect 4D STEM data sets.

The EMPAD is capable of 30-300 kV and provides a high dynamic range (1:1,000,000 e- between pixels), high signal-to-noise ratio (1/140 e-), and high speed (1100 frames per second) on a 128 x 128 pixel array, which makes it the optimal detector for 4D STEM applications. (E.g. Applications where the details of the central and diffracted beams need to be analyzed simultaneously, as in the following ptychography image.)

More details can be found in the  EMPAD datasheet.

From high-throughput, high signal-to-noise ratio elemental mapping in EDS and EELS to oxidation state and surface phonon probing with ultra-high-resolution EELS, the Spectra 300 (S)TEM offers the spectroscopic flexibility to accommodate the widest range of analytical requirements.

The Spectra 300 (S)TEM can be configured with your choice of three different sources with varying energy resolution (X-FEG Mono, X-FEG UltiMono, and X-CFEG), two different EDS detector geometries (Super-X and Dual-X), and a range of Gatan Continuum spectrometers and energy filters, providing you with the freedom to configure the systems to suit your research needs.

The Thermo Scientific EDS detector portfolio provides a choice of detector geometries to suit your experimental requirements and optimize EDS results. Both configurations have a symmetric design, producing quantifiable data.  Note that holder shadowing as a function of tilt is compensated in both detector configurations via built-in Thermo Scientific Velox Software functionality.

The Spectra 300 (S)TEM can be configured with either Super-X (for spectrum cleanliness and quantification) or Dual-X (for the largest solid angle and high-throughput STEM EDS mapping).

The Super-X detector system provides a highly collimated solid angle of 0.7 Sr and a Fiori number greater than 4000. Super-X is designed for STEM EDS experiments, where spectral cleanliness and quantification are critical.

The Dual-X detector system provides a solid angle of 1.76 Sr and a Fiori number greater than 2000. Dual-X is designed for high-throughput STEM EDS experiments, such as EDS tomography, or when signal yield is low and fast mapping is critical.

A DyScO₃ perovskite system is examined with the Dual-X detectors below. The ultra-high brightness (>>1.0 x 10⁸ A/m²/Sr/V^*) of the X-CFEG and the resolving power of the S-CORR probe corrector are used to deliver a probe to the specimen with 150 pA of current and size <80 pm. With these high brightness probe conditions, EDS mapping can be done rapidly with high sampling and a high signal to noise ratio, resulting in, for the first time, sub-Angstrom spatial information in a single elemental, raw, and unfiltered EDS map. A fast Fourier transform of the Sc map shows up to 90 pm resolution. Additionally, the built-in EDS quantification engine in the Velox Software makes STEM EDS on Spectra 300 (S)TEM fast, easy and quantifiable.

When the Spectra 300 (S)TEM is equipped with an X-FEG Mono it is optimized for high-throughput EELS elemental mapping and for probing the fine structure of core-loss edges, extracting sensitive chemical information. The energy resolution of an X-FEG Mono can be tuned between <0.2 eV and 1 eV.

Localized positions of plasmon excitations along a gold nanowire as a function of their excitation energy (between 0.18 – 1.2 eV), investigated with an electron probe of <0.2 eV energy resolution.

A Spectra 300 configured with an X-FEG UltiMono provides the highest possible energy resolution. This configuration is capable of tuning the energy resolution between <0.025 eV and 1 eV.

The Spectra 300 (S)TEM accepts a wide range of holders for in situ experiments with its all-in-one S-TWIN wide-gap pole piece. The Thermo Scientific NanoEx holder family can be seamlessly integrated with the microscope, enabling MEMS device-based heating for atomic imaging at elevated temperatures. Below, gold nanoparticles are heated to 700 degrees Celsius and the resulting motion is captured simultaneously with full frame 4k by 4k pixel resolution at a rate greater than 30 frames per second on a Thermo Scientific Ceta Camera with speed enhancement. The result is high spatial and temporal resolution of highly dynamic molecular behavior.

On the left is a high frame rate movie of gold nano-islands at high temperature, collected on a Ceta Camera with speed enhancement. On the right, the 4k x 4k sensor allows digital zoom while maintaining high resolution in the field of interest.