International team of researchers led by University of Leicester put single molecules in super-fridge

Posted by ap507 at Nov 10, 2016 11:56 AM |
Findings could help to trigger new applications of drugs for diagnostics and develop new materials

Issued by University of Leicester Press Office on  10 November 2016 

An international team of researchers led by the University of Leicester has for the first time observed how a single two-atom-large molecule rotates in the coldest liquid known in nature.

The team consists of researchers from the Department of Physics and Astronomy at the University of Leicester, the Centre National de la Recherche Scientifique (CNRS), Grenoble, France and the Department of Physics in Kerbala, Iraq.

The interactions of molecules in liquids determines chemical reactions and biological processes.

In ordinary liquids the interactions between the molecules is too strong and overshadows the subtle features of rotations.

By choosing a very special liquid composed of helium atoms the researchers reduced the strength of the molecular interactions so that they had the chance to see single molecules rotating.

Lead author Dr Klaus von Haeften from the University of Leicester Department of Physics and Astronomy said: “To introduce molecules into the liquid helium we had to excite the helium using a discharge. 

“This was necessary because ordinary molecules would freeze once they are introduced into liquid helium. By exciting helium in the discharge tiny gas bubbles were formed.”

The researchers observed that by applying pressure the molecules within these bubbles would collide with the ultra-cold liquid and begin to cool and slow down their rotations.

This happened at a rate of more than 100 billion degrees Kelvin (centigrade) per second. At pressures of several atmospheres the molecules reached the slowest possible rotational speed.

The researchers believe that with these molecules they can investigate liquid helium at even lower temperatures.

At these temperatures friction disappears, and the team expects to be able to measure with great precision how molecules respond to this 'superfluid' state.

Dr von Haeften added: “The results of these studies in liquid helium will also be important to understand ordinary liquids, where such observations are impossible to make.

“This may trigger new applications of drugs for diagnostics and therapy and the development of new materials.”

Two of the international researchers involved in the project have conducted their PhD studies at the University of Leicester.

Mrs Nagham Shiltagh (Iraq) is currently investigating how the technology developed in this project could be applied in other areas and Luis Guillermo Mendoza-Luna (Mexico) was involved in setting up the experiment and recording the data and has now assumed an academic position in Mexico.

Luis was sponsored by CONACYT, a distinguished scholarship in Mexico.

The paper 'Excimers in the Lowest Rotational Quantum State in Liquid Helium' is published in the Journal of Physical Chemistry Letters.

The research was funded by British Council, The Leverhulme Trust, Royal Society, Iraqi Ministry of Higher Education and Scientific Research.


Notes to editors:

For more information contact Dr Klaus von Haeften on email

digital object identifier, DOI: 10.1021/acs.jpclett.6b02081

full citation: J. Phys. Chem. Lett. (2016) 7, 4666−4670

The Leverhulme Trust was established by the Will of William Hesketh Lever, the founder of Lever Brothers. Since 1925 the Trust has provided grants and scholarships for research and education; today it is one of the largest all-subject providers of research funding in the UK, distributing approximately £80 million a year. For more information: / @LeverhulmeTrust

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