Tender X-rays show how one of nature’s strongest bonds breaks

Short flashes of an unusual kind of X-ray light at SwissFEL and SLS bring scientists closer to developing better catalysts to transform the greenhouse gas methane into a less harmful chemical. The result, published in the journal Science, reveals for the first time how carbon-hydrogen bonds of alkanes break and how the catalyst works in this reaction.

Methane, one of the most potent greenhouse gases, is being released into the atmosphere at an increasing rate by livestock farming as well as the continuing unfreezing of permafrost. Transforming methane and longer-chain alkanes into less harmful and in fact useful chemicals would remove the associated threats, and in turn make available a huge feedstock for the chemical industry. However, transforming methane necessitates as a first step the breaking of a C-H bond, one of the strongest chemical linkages in nature.

Forty years ago, molecular metal catalysts were discovered that can easily split C-H bonds. The only thing found to be necessary was a short flash of visible light to “switch on” the catalyst and – bafflingly – the strong C-H bonds of alkanes passing nearby were easily broken almost without using any energy. Despite the importance of this so-called C-H activation reaction, it has remained unknown how that catalyst performs this function. Now, experiments at Swiss FEL and SLS have enabled a research team led by scientists at Uppsala University to directly watch the catalyst at work and reveal how it breaks the C-H bonds.

Read more on the PSI website

Image: An X-ray flash illuminates a molecule

Credit: University of Uppsala / Raphael Jay

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Benedetta Casu’s #My1stLight

Synchrotron: Destiny

When I was a physics student, the Physics Department of my University in the capital city of Sardinia organized a journey to Berlin for the senior master students to visit the most important labs. Among them, there was BESSY I. What an incredible experience, everything looked so fantastic, exciting, and complicated.

After that, for sake of curiosity, I attended the Italian synchrotron School that at the time was organized in Sardinia. I attended the school because I wanted to know more about synchrotron light, but I was sure that it would stay a “cultural opportunity” and nothing more.

A few years later I was offered a Ph.D. position at the University of Potsdam. The plan was that I would have been in charge of photocurrent investigations. BUT, the Ph.D. student that was in charge of the beamtime at Synchrotron in the same research group was never back from his vacation preferring to stay in sunny Spain. My supervisor decided that I would take over the Synchrotron beamtimes.

My very first beamtime was with the last photon at BESSY I.

Since then, I had the opportunity to perform wonderful experiments using Synchrotron facilities all over Europe, from working with the world record laterally resolved PEEM-LEEM at BESSY II to measuring XMCD at 150 mK at Petra III. I am also one of the German national delegates of the European Synchrotron and FEL User Organisation (ESUO).

Synchrotron was certainly my destiny

Image: Benedetta Casu during beamtime at BESSY II

Credit: Benedetta Casu