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It is being discussed as a "milestone". For the first time, a German-Israeli research team has succeeded in devising a targeted method to control the process of bond formation between two atoms. Prof. Dr. Christiane Koch and Dr. Wojciech Skomorowski of the University of Kassel were involved in the research efforts. The results of this research have now been published in the prestigious journal Physical Review Letters.
In their experiments, the research team used femtosecond lasers – these are lasers which can emit extremely short light pulses at very high intensity – to fire on magnesium atoms. Under this laser bombardment each pair of magnesium atoms bonded to become Mg2 molecules. The novelty here was that the physicists were able to control the signal of Mg2 molecules by tailoring the light pulses. When the scientists fired a light pulse the frequency of which increased in an exceedingly short interval (a so-called "chirp"), then five times as many Mg2 molecules were observed than without this frequency increase. Conversely, the scientists were able to reduce the yield of new molecules by using a negative chirp.
"Chemical assembly line"
A mechanism of this sort has been sought for a long time. The publisher of the Physical Review Letters, the American Physical Society, therefore highlighted the publication with a synopsis in its online portal 'Physics'. As is explained there, scientists had earlier succeeded in breaking up molecules using tailored laser pulses many times, but it took 30 years to find a way to control the bond-making process. Together with other similar mechanisms, this success could eventually lead to a "chemical assembly line in which lasers slice and weld molecular pieces into a desired end product."
While Israeli members of the team from Haifa conducted the experiments, Prof. Koch and Dr. Skomorowski together with a colleague from Jerusalem provided the theoretical model for understanding the phenomenon. This allowed to refine the experiments and to further increase the observed signal of Mg2 molecules. "Our results are a milestone on the way to being able to control the process of molecular bonding," explained Prof. Koch. "We have shown that the form of the laser pulse affects transitions between various quantum mechanical vibrational levels of the newly formed molecule thus influencing the observed signal."
Prof. Koch heads the group "Theoretical Physics / Quantum Dynamics and Control". Dr. Skomorowski has been working in the group since 2013 as a Humboldt fellow.
Photo of Prof. Dr. Christian Koch (photo: private) at: http://www.uni-kassel.de/uni/fileadmin/datas/uni/presse/anhaenge/2015/Koch_Chris...
Photo of Dr. Wojciech Skomorowski at: http://www.uni-kassel.de/uni/fileadmin/datas/uni/presse/anhaenge/2015/skomorowsk...
Abstract of the article: http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.114.233003
Recognition of the American Physical Society: http://physics.aps.org/synopsis-for/10.1103/PhysRevLett.114.233003
Contact:
Prof. Dr. Christiane Koch
University of Kassel
Department "Theoretical Physics III / Quantum Dynamics and Control"
Preferably by email: christiane.koch@uni-kassel.de
Tel.: +49/ 561 804 -4407
Prof. Dr. Christiane Koch. Foto: privat.
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