Researchers broke the record for the shortest pulse of electrons ever

In ordinary circuits, pulses of electrons are limited by the frequency at which electrons can oscillate inside matter. According to Goulielmakis, a pulse should last at least half a cycle of these oscillations due to the fact that it is the cycle creates a “pushing force” for electrons. Light, meanwhile, oscillates at a much higher frequency, which led Goulielmakis and his team to use a short burst of light to trigger a pulse of electrons.

Using this technique in 2016, the scientists created a flash of visible light lasting only 380 attoseconds. Now, they have gone a step further and used lasers to knock electrons off the tip of a tungsten needle and into a vacuum. Using this method, they recorded a 53-attosecond pulse of electrons. According to Goulielmakis, this is a fifth of the time it would take an electron to orbit its nucleus in a hydrogen atom.

The new breakthrough could lead to state-of-the-art electron microscopes

Such a short pulse of electrons could enhance electron microscopes, allowing them to reveal the movement of particles more clearly. Late last year, we reported that scientists were developing a new type of electron microscope that was inspired by the James Webb Space Telescope.

The new microscope uses mirror segments to sort and gather light on a microscopic scale, take three-dimensional images of molecules both in position and orientation, and capture clearer images.

Goulielmakis and his team’s work could also help to improve electron microscope imaging. In an interview with NewScientist, he said electron microscope images are often “a little bit blurry. It’s not necessarily that they don’t have a good resolution; it’s because the electron is not sitting still at a specific point, right? It’s just making a cloud around the atoms.” However, the scientist explained that “the attosecond electron pulse will help the resolution to be fast enough to capture electrons in motion.”

“If we create electron microscopes using our attosecond electron pulses, then we have a sufficient resolution not only to see atoms in motion, which would be already an exciting thing but even how electrons jump among those atoms.”

The study paper was published in Nature.

Study Abstract:

Field emission of electrons underlies great advances in science and technology, ranging from signal processing at ever higher frequencies1 to imaging of the atomic-scale structure of matter2 with picometre resolution. The advancing of electron microscopy techniques to enable the complete visualization of matter on the native spatial (picometre) and temporal (attosecond) scales of electron dynamics calls for techniques that can confine and examine the field emission on sub-femtosecond time intervals. Intense laser pulses have paved the way to this end3,4 by demonstrating femtosecond confinement5,6 and sub-optical cycle control7,8 of the optical field emission9 from nanostructured metals. Yet the measurement of attosecond electron pulses has remained elusive. We used intense, sub-cycle light transients to induce optical field emission of electron pulses from tungsten nanotips and a weak replica of the same transient to directly investigate the emission dynamics in real-time. Access to the temporal properties of the electron pulses rescattering off the tip surface, including the duration τ = (53 as ± 5 as) and chirp, and the direct exploration of nanoscale near fields open new prospects for research and applications at the interface of attosecond physics and nano-optics.