| Title | Electron Microscope Detector Achieves Record Resolution | |
| Date | Friday July 20 2018, @01:59AM | |
| Author | martyb | |
| Topic | ||
| from the when-nano-is-not-small-enough dept. | ||
Image resolution in electron microscopy has traditionally been improved by increasing both the numerical aperture of the lens and the energy of the electron beam, which does for the microscope what light does for a camera or an optical microscope – illuminates the subject.
Previous records for resolution were achieved with an aberration-corrected lens and super-high beam energy – 300 kiloelectronvolts (keV) – to obtain sub-ångström resolution. Atomic bonds are generally between 1 and 2 ångströms (Å) long – an ångström is 0.1 nanometers – so sub-ångström resolution would allow one to easily see individual atoms. The Muller group was able to reach a resolution of 0.39 Å – a new world record – and at a lower, less damaging beam energy where resolution from the aberration corrected lenses alone was 0.98 Å.
Muller's group used the EMPAD and a technique known as ptychography: As the electron beam scans the sample, the detector collects both full-position and momentum distributions of the scattered electrons in overlapping steps. The image is reconstructed from the resulting 4-dimensional data set.
The group used a beam energy of just 80 keV so as not to destroy the MoS2. Despite the low beam energy, the resolution using EMPAD is so good, the microscope is able to detect with startling clarity a missing sulfur atom – "a defect in the lattice," Gruner said – in a 2-D material. "That's astounding to me," he said.
Ptychography on Wikipedia
The new resolution will be useful in nanotechnology.
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printed from SoylentNews, Electron Microscope Detector Achieves Record Resolution on 2024-05-07 18:24:06