According to Heisenberg’s uncertainty principle, it’s impossible to know both the position and the speed of an electron at any one time. However, a team of physicists in Sweden has now shown that it can be done — through superposition (interference) of two short pulses of light with different wavelengths.
Isinger et al documented the incredibly brief moment when two electrons in a neon atom are emitted. Image credit: Marcus Isinger.
Marcus Isinger, a doctoral student at Lund University, and co-authors determined how long it takes for an electron to be emitted from an atom of the noble gas neon.
The result is 20 attoseconds, or 20 billionths of a billionth of a second.
“When light hits the atom, the electrons absorb the energy from the light. An instant later the electrons are freed from the binding powers of the atom,” Isinger said.
“This phenomenon, called photoionization, is one of the most fundamental processes of physics and was first theoretically mapped by Albert Einstein, who was awarded the Nobel Prize in Physics in 1921 for this particular discovery.”
Photoionization is about the interaction between light and matter. This interaction is fundamental to photosynthesis and life on Earth — and enables physicists to study atoms.
“When atoms and molecules undergo chemical reactions, the electrons are the ones that do the heavy lifting,” Isinger explained.
“They regroup and move to allow new bonds between molecules to be created or destroyed. Following such a process in real time is a bit of a holy grail within science. We have now come one step closer.”
Although neon is a relatively simple atom with a total of 10 electrons, the experiment required both extremely careful timing, with a level of accuracy within an attosecond, and very sensitive electron detection that could distinguish between electrons whose speed differed only by around one thousandth of an attojoule.
The finding confirms several years of theoretical work and shows that attophysics is ready to take on more complex molecules.
“Being able to observe how molecules exchange electrons during a chemical reaction opens the door to completely new types of studies of a number of fundamental biological and chemical processes,” Isinger said.
The research appears in the journal Science.
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M. Isinger et al. Photoionization in the time and frequency domain. Science, published online November 2, 2017; doi: 10.1126/science.aao7043
