The LEAP® 4000 XHR local electrode atom probe instrument from Cameca Instruments Inc. is used to perform the analytical analysis known as atom probe tomography (APT). APT analysis results in three-dimensional (3-D) atom-by-atom point cloud maps with atomic-scale resolution and part per million elemental sensitivity of a wide variety of materials ranging from soft biological materials to metal alloys, including low electrical conductivity materials such as ceramics, semiconductors, and oxides. At EMSL, APT advances science relevant to the Department of Energy, Office of Science, Biological and Environmental Research program. It does so by providing unique compositional interface analysis and microstructural characterization of bioorganic-mineral interfaces and chemical gradients in biological systems to better understand the complex chemical language nature uses to communicate and perform fundamental functions relevant to energy and the environment.
- Supporting the Structural Biology Integrated Research Platform, APT provides atomic-scale resolution, and compositional and structural information for proteins and other biomolecular complexes to inform structure-based computational chemistry and simulation models aimed at understanding key biochemical functions and pathways.
- Supporting the Biogeochemical Transformations Integrated Research Platform, APT provides atomic-scale insight at the interface between microbes and soil minerals that affect the transformation and mobility of critical nutrients, contaminants, aerosols, particles, and compounds within the environment.
EMSL is working to expand the application of APT to materials traditionally not studied using this technique such as hydrated biological materials and reactive metal surfaces. This involves the development of a vacuum chamber system called the Environmental Transfer Hub that enables the environmentally protected transfer of cryogenic and/or air sensitive specimens between the tools used to prepare them such as a focused ion beam-scanning electron microscope (FIB/SEM) or a gas-phase reactor, as well as the LEAP. As a result, this capability allows for the analysis of cryogenically prepared, hydrated biological materials to map ionic gradients and even potentially map atomic-scale macromolecular structure. Additionally, new modes of APT analysis are also possible, including in situ and in operando modes, providing insight into both corrosion and surface chemistry dynamics and the influence of strong electric fields on such phenomena.
Atom Probe Tomography is used by researchers across Pacific Northwest National Laboratory for other initiatives, as well. For example, the technology is used to support corrosion dynamics studies by analyzing atomic-scale material transformations induced by exposure to oxidative environments and the diffusion of oxygen and hydrogen within the bulk using isotopic tracers. It also supports heterogeneous catalysis studies through the analysis of metallic surface and sub-surface transformations under the action of a surface chemical reaction and/or in presence of strong electric fields. APT also supplements tritium science and technology through the analysis of chemical and structural transformations under the action of corrosive environments and/or after the exposure to radioactive environments.
- LEAP® 4000 XHR Local Electrode Atom Probe (Cameca Instruments Inc.)
(Instr. ID 34110, Availability: 10 hours/day 5 days/week)
- Maximum Pulse Repetition Rate – Voltage Mode: 200 kHz
- Maximum Pulse Repetition Rate – Laser Mode: 250 kHz
- Laser Power: > 300 mW
- Laser Wavelength: 355 nm
- Sample Temperature: 25–150K
- Maximum Energy per Pulse: 0.5 nJ
- Dynamic Range: > 1000X
- Field-of-View: > 200 nm (limited by the specimen geometry)
- Typical Analysis Volume: approx. 100 nm x 100 nm x 300 nm
- Collection Rate: > 50 M ions per hour
- Detection Efficiency: approx. 40%
- Lateral Resolution: 0.2 nm (using W-tip)
- Depth Resolution: 0.1 nm (using W-tip)
- Mass Resolution: Full FoV is ≥ 60° solid angle as measured from position of poles in the aluminum ion-desorption image (all results stem from using Al specimen)
- Sensitive to every elemental isotope
- Full Width at Half Maximum: 1/1000
- Full Width at 10% Maximum: 1/475
- Full Width at 1% Maximum: 1/300
- Generally, no matrix corrections or sensitivity factors required for quantification
- In Situ Reactor
- Temperature Range: Room temperature to 500oC
- Pressure Range: 10-9 bar to 1 bar
- Tungsten sample holder available
- Gases Available: D2, O2, 18O2, CO/Ar(10%), CO2, N2, Ar, H2O
- Operando Mode
- Temperature Range: 100 to 320 K
- Pressure Range: 10-10 to 10-8 mbar
- Gases Available: He, Ne, O2, CO
Tips for success
- Specimens for analysis with APT must be solid. It is not possible to have materials in the gas or liquid phase during analysis.