Researchers at Ohio State University have captured the first-ever images of atoms moving in a molecule.
OHIO, US: Researchers have recorded the first real-time image of two atoms vibrating in a molecule by means of a new ultrafast camera. The researchers’ use the energy of a molecule’s own electron as a kind of ‘flash bulb’ to illuminate the molecular motion. The team used ultrafast laser pulses to knock one electron out of its natural orbit in a molecule. The electron then fell back toward the molecule scattered off of it.
According to Louis DiMauro, Professor, Ohio State University, the feat marks a first step toward not only observing chemical reactions, but also controlling them on an atomic scale. “Through these experiments, we realized that we can control the quantum trajectory of the electron when it comes back to the molecule, by adjusting the laser that launches it. The next step will be to see if we can steer the electron in just the right way to actually control a chemical reaction,” said DiMauro.
A standard technique for imaging a still object involves shooting the object with an electron beam, bombarding it with millions of electrons per second. A technique called laser induced electron diffraction (LIED) is commonly used in surface science to study solid materials. Here, the researchers used it to study the movement of atoms in a single molecule.
The molecules of study were simple ones, nitrogen and oxygen. nitrogen and oxygen are common atmospheric gases, and scientists already know every detail of their structure, so these two very basic molecules made a good test case for the LIED method. In each case, the researchers hit the molecule with laser light pulses of 50 femtoseconds, or quadrillionths of a second. They were able to knock a single electron out of the outer shell of the molecule and detect the scattered signal of the electron as it recollided with the molecule.
DiMauro and Cosmin Blaga, Postdoctoral Researcher, Ohio University linked the scattered electron signal to the diffraction pattern that light forms when it passes through slits. Given only the diffraction pattern, scientists can reconstruct the size and shape of the slits. In this case, given the diffraction pattern of the electron, the physicists reconstructed the size and shape of the molecule.
The key is that during the brief span of time between when the electron is knocked out of the molecule and when it recollides, the atoms in the molecules have moved. The LIED method can capture this movement, ‘similar to making a movie of the quantum world,’explained Blaga. “You could use this to study individual atoms but the greater impact to science will come when we can study reactions between more complex molecules. Looking at two atoms, that’s a long way from studying a more interesting molecule like a protein,” explained DiMauro.
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