MERLIN (Carl Zeiss) field emission scanning electron microscope (FESEM): The Merlin FESEM features standard detectors, ‘SE2’ (Everhart-Thornley type) and ‘in lens’ (annular secondary electron). The Merlin also includes an in lens EsB detector with filtering grid, offering energy and angle-selective backscattered electron imaging for highest material contrast. It also includes the multi-segment, Si diode-based CZ BSD back scattered electron detector. X-ray microanalysis is available using the Oxford Instruments EDS with integrated INCA software. In addition to SEM, the Merlin includes STEM detection for high resolution images of TEM samples. The column also offers high resolution imaging at low acceleration voltages and low beam currents.
Technical data: resolution (optimal WD) = 0.8 nm @ 15 kV, 1.4 nm @ 1 kV, 0.6 nm @ 30 kV (STEM mode); magnification = 12 – 2,000,000 x in SE mode; 5-axis motorized stage, –3 to 70 tilt; chamber volume = 330 mm (Ø) x 270 mm (h); local charge compensation device (stainless steel needle injects nitrogen gas into the region of interest); image resolution up to 6144 x 4608 pixels.
The system was recently upgraded with the Ultim Max Energy Dispersive Spectroscopy detector from Oxford. The Ultim Max boasts several key advantages over its predecessor:
- Enhanced Sensitivity: A larger sensor area (65 mm²) significantly increases the X-ray counts per second. This enables better detection of low concentration elements and faster analysis times.
- Better spatial resolution: The Ultim Max positions the sensor closer to the sample, enabling the collection of more X-rays in a shorter timeframe. This allows one to achieve better spatial resolution in elemental mapping, all while requiring less beam current.
- Faster Analysis, Less Risk of sample damage: Faster data collection and less beam current minimizes the chance of sample damage caused by prolonged exposure to the electron beam.
- Better Point and ID: Even with high count rates (130,000 counts per second for Manganese Kα), the detector maintains a spectral resolution of at least 127 eV. This resolution allows for accurate identification of elements with closely spaced peaks in the spectrum.
- Light Element Detection: The Ultim Max is equipped with a Silicon-Nitride Thin Window (SATW), enabling the detection of X-rays from elements as light as Beryllium (Be).
- Integrated Motorized Slide: The user now has the ability to effortlessly insert and retract the detector thorough software controls.
The Merlin FESEM was acquired through the support of the MRI program of the National Science Foundation under Award Number DMR-0923251.
The EDS Detector upgrade was acquired through the support of New York University.
Please visit the Electron Microscopy Facility web page for more information.