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: email@example.com
http://dx.doi.org/10.1038/nphys3085 - Abstract
Reto Caluori | Universität Basel
Staying in Shape
16.08.2018 | Max-Planck-Institut für molekulare Zellbiologie und Genetik
Chips, light and coding moves the front line in beating bacteria
16.08.2018 | Okinawa Institute of Science and Technology (OIST) Graduate University
Scientists at the University of California, Los Angeles present new research on a curious cosmic phenomenon known as "whistlers" -- very low frequency packets...
Scientists develop first tool to use machine learning methods to compute flow around interactively designable 3D objects. Tool will be presented at this year’s prestigious SIGGRAPH conference.
When engineers or designers want to test the aerodynamic properties of the newly designed shape of a car, airplane, or other object, they would normally model...
Researchers from TU Graz and their industry partners have unveiled a world first: the prototype of a robot-controlled, high-speed combined charging system (CCS) for electric vehicles that enables series charging of cars in various parking positions.
Global demand for electric vehicles is forecast to rise sharply: by 2025, the number of new vehicle registrations is expected to reach 25 million per year....
Proteins must be folded correctly to fulfill their molecular functions in cells. Molecular assistants called chaperones help proteins exploit their inbuilt folding potential and reach the correct three-dimensional structure. Researchers at the Max Planck Institute of Biochemistry (MPIB) have demonstrated that actin, the most abundant protein in higher developed cells, does not have the inbuilt potential to fold and instead requires special assistance to fold into its active state. The chaperone TRiC uses a previously undescribed mechanism to perform actin folding. The study was recently published in the journal Cell.
Actin is the most abundant protein in highly developed cells and has diverse functions in processes like cell stabilization, cell division and muscle...
Scientists have discovered that the electrical resistance of a copper-oxide compound depends on the magnetic field in a very unusual way -- a finding that could help direct the search for materials that can perfectly conduct electricity at room temperatur
What happens when really powerful magnets--capable of producing magnetic fields nearly two million times stronger than Earth's--are applied to materials that...
08.08.2018 | Event News
27.07.2018 | Event News
25.07.2018 | Event News
16.08.2018 | Life Sciences
16.08.2018 | Earth Sciences
16.08.2018 | Life Sciences