Ultrashort laser pulses make greenhouse gas reactive

Ultrashort laser pulses make greenhouse gas reactive
Researchers at the university have discovered a new way to create a highly reactive form of the greenhouse gas CO2 with the help of laser pulses © Kevin Doncaster Flickr CC BY-2.0

Researchers at the University of Bonn, Germany, are in the process of making significant contributions to removing the greenhouse gas carbon dioxide from the atmosphere and using it as a material.

Researchers at the university have discovered a new way to create a highly reactive form of the greenhouse gas CO2 with the help of laser pulses.

Photosynthesis is one example of how CO2 can be taken from the air and transformed into a raw material: oxygen. Professor Dr Peter Vöhringer, from the Institute for Physical and Theoretical Chemistry of the University of Bonn, said: “Scientists have been striving to mimic this model for a long time, for instance in order to use carbon dioxide for the chemical industry.”

One difficulty the researchers face is that it is very difficult to push carbon dioxide into a new partnership with other molecules.

Vöhringer and his team have discovered a way to generate a highly reactive variant of the inert and hard-to-bind greenhouse gas. The researchers used an ‘iron complex’ – the centre contains a positively charged iron atom, to which the constituents of the CO2 are already bound multiple times. The resulting product was a so-called ‘carbon dioxide radical’, which also forms a new bond with a certain radicality.

These radicals have a single electron in their outer shell that instantly wants to bind permanently to another molecule or atom. Steffen Straub, lead author from the team, said: “It is this unpaired electron that distinguishes our reactive radical anion bound to the central iron atom from the inert carbon dioxide and makes it so promising for chemical processes.”

Spectrometer shows molecules at work

Researchers are able to watch the molecules at work with their laser and infrared spectrometer, which measures the characteristic vibrations of the molecules. This ‘fingerprint’ allows them to identify the bonds between different atoms. Straub continued: “The formation of the carbon dioxide radical within the iron complex changes the bonds between the atoms, which reduces the frequency of the characteristic carbon dioxide vibration.”

Scientists were able to prove that the laser pulses produce the reactive carbon dioxide radical. First, the team simulated the vibrational spectra of the molecules on the computer, then they compared the calculations to the measurements.

Vöhringer said: “Our findings have the potential to fundamentally change ideas about how to extract the greenhouse gas carbon dioxide from the atmosphere and use it to produce important chemical products.

“Nonetheless, our results provide clues as to how such a catalyst would have to be designed.”

Source: AlphaGalileo

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