To not only observe but really understand a chemical reaction, scientists need to know the behavior of electrons within molecules. Until now, it has not been technically possible to observe electrons because they move unimaginably fast. Now this has been achieved by a group of European researchers using attosecond laser pulses.
An attosecond is a billionth of a billionth of a second. In an attosecond, light travels less than a millionth of a millimeter - that's just the way from one end of a smaller molecule to another. By comparison, light can circle our globe eight times in one second. And that's exactly why the physicists make the immense effort to produce such short laser flashes: they can "photograph" the movement of the electrons within a molecule like in a photo series.
In the European research team Prof. Marc Vrakking, director at the Max Born Institute for Nonlinear Optics and Short Pulse Spectroscopy (MBI) in Berlin, worked together with groups and others. from Milan, Amsterdam, Lund (Sweden), Garching, Lyon and Madrid. The physicists first studied the hydrogen molecule (H2) - it is the simplest molecule with two protons and two electrons. The researchers wanted to find out exactly how the ionization takes place in a hydrogen molecule, where an electron is removed from the molecule, and how the remaining electron rearranges itself within the molecule. Marc Vrakking explains: "In our experiment we were able to show for the first time that with an attosecond laser we are actually able to observe the movement of electrons in the molecule. Our experiment can be imagined as follows: First, we irradiated a hydrogen molecule with an attosecond laser pulse. As a result, an electron is released from the molecule - the molecule is ionized. At the same time, we split the molecule into two parts with an infrared laser beam, as with a tiny pair of scissors. Now we have looked at how the charge is distributed over the two fragments - because one electron is missing, one part is now neutral and one part is positively charged. So we knew where the remaining electron was, namely in the neutral part. "