Scientists have achieved a breakthrough in observing the electron motion in water molecules using attosecond X-ray pulses. This technique allows them to study the electronic structure and dynamics of molecules in the liquid phase on a timescale previously inaccessible with X-rays.
What is attosecond X-ray spectroscopy and why is it important?
Attosecond X-ray spectroscopy is a method of probing the ultrafast dynamics of electrons in matter using X-ray pulses that last for only a few billionths of a billionth of a second (10^-18 seconds). By using such short pulses, scientists can capture the electron motion before the atomic nuclei have time to move, thus revealing the instantaneous electronic response to an external perturbation. This is important for understanding how radiation affects matter, as well as for exploring the fundamental properties of electrons and their interactions with other particles and fields.
How did the scientists track the electron motion in water molecules?
The scientists, from several Department of Energy national laboratories and universities in the U.S. and Germany, performed their experiment at the Linac Coherent Light Source (LCLS) at SLAC National Accelerator Laboratory. They used a synchronized pair of attosecond X-ray pulses to irradiate a jet of liquid water and measure the photoemission of electrons from the water molecules. The first pulse ionized the water molecules, creating a hole in their innermost shell, while the second pulse probed the filling of that hole by an electron from an outer shell. By varying the time delay between the two pulses, the scientists were able to track the electron motion on the attosecond timescale.
What are the implications of tracking electron motion in water molecules?
The experiment marks the first time that attosecond X-ray spectroscopy has been applied to liquid samples, which are more relevant for studying chemical reactions and biological processes than isolated atoms or molecules in vacuum. The technique reveals how the electrons in water molecules interact with each other and with their environment, which is crucial for understanding how water behaves as a solvent and how it participates in various chemical and biological processes. The findings also open up a new field of experimental physics that can explore the electronic structure and dynamics of complex systems in the liquid phase.
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