CART Facilities
Local Electrode Atom Probe (LEAP)
An Imago Scientific Local Electrode Atom Probe (LEAP) instrument was added to CART in December 2005, with a laser-pulsed evaporation technique added in July 2006.
This instrument allows for time-of-flight mass spectrometry to be conducted on field-emitted ions originating from a needle-shaped specimen.
Using a local electrode, electrical or 100fs laser pulses between the specimen and the electrode cause ions to be emitted from the surface and detected on an imaging plate at a rate up to 9 million atoms per hour.
The imaging plate also allows for spatially resolved ion placement with a resolution of ~0.2nm. Ultimately, three-dimensional atomic-resolution data can be reconstructed from virtually any conductive or semiconducting sample.
Utilizing the nanofabrication abilities of the dual beam focused ion beam (FIB) system, site-specific specimen preparation is possible.
Hardware recently developed at UNT by Dr. Brian Gorman allows for LEAP specimens to be readily examined in the transmission electron microscope (TEM) before and after atom probe runs. Thus, 3-D structural information may be directly compared between the two techniques.
Instrument Specifications
Data Collection Rate
- Pulse repetition rate 200 kHz (voltage), 250 kHz (laser)
- Maximum data collection rate 2 million ions/minute
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Laser
•Wavelength:
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532 nm
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•Average Power:
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3 mW
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•Beam Quality, M2 :
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<1.2
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•Pulse Duration:
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<12 ps
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•Pulse Energy
(user selectable):
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0.2 nJ to 10 nJ
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•Pulse Energy Stability:
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< 1% rms
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Mass Resolution
- Ion mass-to-charge-ratio range 1 to 300 amu
- Resolution up to ≈ 1/250 amu (FWHM)
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Spatial Resolution
- Field of view 200 nm
- Detector microchannel plate (MCP) size > 4400mm2
- Lateral resolution 0.1 nm
- Depth resolution 0.05 nm
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Click here for information about Equipment Use and/or Training.
Click here for information about Equipment Rates.
Click here to go to the Online Schedule.
For more information about CART equipment, contact David Diercks at 940-369-8106 or drd0036@unt.edu
