Researchers at the University of Basel have succeeded in observing the “forbidden” infrared spectrum of a charged molecule for the first time. These extremely weak spectra offer perspectives for extremely precise measurements of molecular properties and may also contribute to the development of molecular clocks and quantum technology. The results were published in the scientific journal Nature Physics.
Spectroscopy, the study of the interaction between matter and light, is probably the most important method for investigating the properties of molecules. Molecules can only absorb light at well-defined wavelengths which correspond to the difference between two quantum-mechanical energy states.
This is referred to as a spectroscopic transition. An analysis of the wavelengths and the intensity of the transitions provides information about the chemical structure and molecular motions, such as vibration or rotation.
In certain cases, however, the transition between two energy levels is not permitted. The transition is then called “forbidden”. Nevertheless, this restriction is not categorical, meaning that forbidden transitions can still be observed with an extremely sensitive method of measurement. Although the corresponding spectra are extremely weak, they can be measured to an exceptionally accurate degree. They provide information on molecular properties with a level of precision not possible within allowed spectra.
Precise measurements of molecular properties
Within the framework of the National Centre of Competence in Research QSIT – Quantum Science and Technology, the research group headed by Professor Stefan Willitsch at the University of Basel's Department of Chemistry has established methods for the precise manipulation and control of molecules on the quantum level.
In the present study, individual charged nitrogen molecules (ions) were generated in a well-defined molecular energy state. The ions were then implanted into a structure of ultra-cold, laser-cooled calcium ions – a Coulomb crystal – in an ultra-high vacuum chamber. The molecular ions were thus cooled to a few thousandths of a degree above absolute zero to localize in space. In this isolated, cold environment, the molecules could be investigated without perturbations over long periods of time. This enabled the researchers to excite and observe forbidden transitions in the infrared spectral domain using an intensive laser.
Potential for new applications
The new method paves the way for new applications, such as the highly precise measurement of molecular properties, the development of extremely precise clocks based on individual molecules and quantum information processing using molecules. It also offers perspectives to test fundamental concepts using spectroscopic precision measurements on single molecules which were up to now the domain of high-energy physics. One example is the important question whether the physical constants of nature are actually really constant.
Matthias Germann, Xin Tong and Stefan Willitsch
Observation of electric-dipole-forbidden infrared transitions in cold molecular ions
Nature Physics, published online 21 September 2014 | doi: 10.1038/nphys3085
Prof. Dr. Stefan Willitsch, University of Basel, Department of Chemistry, phone: +41 61 267 38 30, email: firstname.lastname@example.org
http://dx.doi.org/10.1038/nphys3085 - Abstract
Reto Caluori | Universität Basel
Warming ponds could accelerate climate change
21.02.2017 | University of Exeter
An alternative to opioids? Compound from marine snail is potent pain reliever
21.02.2017 | University of Utah
In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport
Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...
The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.
The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...
Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...
Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".
Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...
13.02.2017 | Event News
10.02.2017 | Event News
09.02.2017 | Event News
21.02.2017 | Earth Sciences
21.02.2017 | Medical Engineering
21.02.2017 | Trade Fair News