Recently a Cameca Local Electrode Atom Probe (LEAP 5000 XS) instrument was installed in December 2018 as a replacement to MRF's original Imago/Cameca LEAP 3000XHR, providing greatly enhanced capabilities for the determination of the three-dimensional compositional distribution within solid materials at the scale of individual atoms.   

An Imago Scientific Local Electrode Atom Probe (LEAP 3000X HR) instrument was added in December 2005, with a laser-pulsed evaporation technique added in July 2006. A reflectron lens, larger field of view detector, and digital field ion microscopy (FIM) capabilties were added in 2009. In October 2018 the LEAP 3000XHR was retired and replaced by a state-of-the-art Cameca LEAP 5000XS.

This instrument allows for time-of-flight mass spectrometry to be conducted on field-emitted ions originating from a needle-shaped specimen.

Electrical or laser pulses between the specimen and the electrode cause ions to be field evaporated from the surface and detected on an imaging plate at rates of up to ten of millions per hour.

The imaging plate also allows for spatially resolved ion placement with a resolution of ~0.2nm generating a data set that can be used to produce three-dimensional atomic-resolution reconstructions of samples.

Utilizing the nanofabrication abilities of the dual beam focused ion beam (FIB) system, site-specific specimen preparation is possible.

Hardware developed at UNT 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
  • Maximum rate                            5 million ions/minute
  • Maximum collected (UNT)     ~ 600 million
  • Detection Efficiency                ~ 80%

Voltage Pulse Mode

  • DC Sample Bias           0.5 - 15kV
  • Pulse Bias DC fraction  1 - 35%
  • Pulse Duration             <12ps
  • Pulse Repetition Rate   2 - 500 kHz

 

Laser Pulse Mode

  • Wavelength  -  355nm
  • Pulse Duration - <15ps
  • Average Power - 350mW @ 80 MHz
  • Pulse Energy (user selectable) - 0.1 pJ to 1000 pJ
  • Pulse Repetition Rate - 10 - 1000 kHz
  • Beam steering and focus - Automatic
  • Drift correction - Automatic

Mass Resolution

  • Ion mass-to-charge-ratio range:
    • 3kV, 100kHz      1 - 500 amu
    • 3kV, 200kHz      1 - 150 amu
  • FWHM      >1/800 amu
  • FW10%M >1/400 amu
  • FW1%M   >1/200 amu

Spatial Resolution

  • Field of view (Al+)                  250 nm
  • Lateral resolution (W)             0.2 nm
  • Depth resolution (W)              0.1 nm