The subatomic world is hard to image not just because it’s incredibly tiny, but super fast too. Now physicists at the University of Arizona have developed the world’s fastest electron microscope to capture events lasting just one quintillionth of a second.
A good camera, with a shutter speed measured in milliseconds, might be able to snap a clear photo of a person running. But the fastest “cameras” in the world – transmission electron microscopes – can capture events on the scale of attoseconds, like photos of electrons running. An attosecond is one quintillionth of a second, which makes a millisecond (a thousandth of a second) seem like an eternity.
If we scale that up, there are as many attoseconds in one second as there are seconds in 31.7 billion years – that’s more than twice as long as the universe has existed. There’s just some truly unfathomable numbers here.
Anyway, previous efforts to capture events on that kind of timescale have gotten it down as far as 43 attoseconds, which the researchers at the time called “the shortest controlled event ever created by humankind.” And now, the U of A team has gone even shorter, freezing time at just one attosecond.
The new work built off research by Pierre Agostini, Ferenc Krausz and Anne L’Huilliere, who generated the first light pulses that were short enough to be measured in attoseconds. This earned the team the Nobel Prize in Physics in 2023.
For the new study, the researchers developed what they call an “attomicroscope.” First, a pulse of ultraviolet light is fired off into a photocathode, which releases ultra-fast electrons inside the attomicroscope. Then, a laser pulse is split into two beams, which are both sent into the electrons moving through the microscope. One of those beams is polarized, and they arrive at slightly different times, generating a “gated” electron pulse that can image a sample – in this case, graphene.
Using this technique, the team was able to generate electron pulses lasting just a single attosecond, allowing them to observe ultrafast electron motion that normally can’t be seen. The researchers say this breakthrough could have applications in quantum physics, chemistry and biology.
“The improvement of the temporal resolution inside of electron microscopes has been long anticipated and the focus of many research groups, because we all want to see the electron motion," said Mohammed Hassan, an author of the study. "These movements happen in attoseconds. But now, for the first time, we are able to attain attosecond temporal resolution with our electron transmission microscope – and we coined it 'attomicroscopy.' For the first time, we can see pieces of the electron in motion.”
The research was published in the journal Science Advances.
Source: University of Arizona
