October eight, 2019
A linear accelerator delivers high-energy electrons that can be utilized to picture samples too thick for typical transmission electron microscopes.
T. Sannomiya et al., Phys. Rev. Lett. (2019)
A transmission electron microscope (TEM) can picture a pattern with subatomic spatial decision. The pattern, nevertheless, should be thinner than about 100 nm to sufficiently transmit the TEM electron beam—an vital restriction when learning organic cells and tissues or defects buried inside supplies. For the reason that transmittivity of a pattern will increase with electron power, accelerating the electrons can relieve these thickness constraints. Now, Takumi Sannomiya of Tokyo Institute of Expertise and colleagues have demonstrated a compact TEM during which the electron power is boosted by a linear accelerator. Such a TEM may picture samples an order of magnitude thicker than these measurable with typical TEMs.
Excessive-energy TEMs in a position to examine micrometer-thick samples have already been developed. These machines, nevertheless, speed up the electrons with large dc voltages, whose shielding requires building-sized amenities. To scale back the gadget dimension, the thought of Sannomiya and colleagues is to make use of a linear accelerator within the type of a radio frequency cavity. In such a cavity, a propagating electromagnetic wave produces an oscillating potential that accelerates a practice of electron pulses timed to coincide with the potential peaks.
The group’s gadget matches in a laboratory room and accelerates electron pulses to energies of 500 keV—about half that achieved within the large-scale amenities. After passing via the pattern, the electrons are decelerated by one other radio frequency cavity in order that they are often measured with a typical TEM detector. Imaging reference samples with identified geometries, the group demonstrates that the setup can carry out microscopy with high-energy electrons whereas attaining subnanometer decision. Using cavities manufactured from superconductors may produce electrons with even increased power and make the gadget smaller and extra power environment friendly.
This analysis is revealed in Bodily Assessment Letters.
Matteo Rini is the Deputy Editor of Physics.