14 DAY TRIAL // The electron has been a theoretical thing for a long time. Like something you know for sure it exists, but you cannot show it to the others. But now you can. In a research published in the "Physical Review Letters," researchers have filmed an electron for the first time ever, moving on a light wave after just having been expelled from an atom.
The high speed of the electrons impeded previous attempts to take a picture of an electron. But now, this has been possible due to a new technology generating short pulses from intense laser light (attosecond pulses).
"It takes about 150 attoseconds for an electron to circle the nucleus of an atom. An attosecond is 10-18 seconds long, or, expressed in another way: an attosecond is related to a second as a second is related to the age of the universe," said co-author Johan Mauritsson, an assistant professor in atomic physics at the Faculty of Engineering, Lund University, in Sweden.
Using another laser, the team managed to head an electron into a collision with an atom, and all this was recorded on film.
"We have long been promising the research community that we will be able to use attosecond pulses to film electron motion. Now that we have succeeded, we can study how electrons behave when they collide with various objects, for example. The images can function as corroboration of our theories," said Mauritsson.
The film recorded a sole oscillation of the light, but the speed had to be decreased significantly so that we could see something. Movements of electrons have previously been measured by assessing their spectrum. That method only determined the result of an electron's movement, but the current results come with the most minute details.
Attosecond pulses were created for the first time about 2 years ago, however this technology had to be combined, as by themselves, these pulses are too weak to bring clear images.
"By taking several pictures of exactly the same moment in the process, it's possible to create stronger, but still sharp, images. A precondition is for the process to be repeated in an identical manner, which is the case regarding the movement of an electron in a ray of light. We started with a so-called stroboscope. A stroboscope enables us to 'freeze' a periodic movement, like capturing a hummingbird flapping its wings. You then take several pictures when the wings are in the same position, such as at the top, and the picture will turn out clear, despite the rapid motion," said Mauritsson.