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Experimental Nuclear Magneto-Optic Spectroscopy

Periodic Reporting for period 1 - NMOSPEC (Experimental Nuclear Magneto-Optic Spectroscopy)

Reporting period: 2015-10-01 to 2017-09-30

The field of spectroscopy offers methods for investigating structure of molecules and materials. It is an indispensable tool for discovering new molecules, exploring materials with novel properties, and assuring quality of the products in industries ranging from food through manufacturing of pharmaceuticals to the material engineering.
Spectroscopy encompasses a wide range of methods. In this project, we have targeted at development of new spectroscopic techniques, which would allow to extend the possibilities of studies of molecules with very high resolution. These so-called nuclear magneto-optic spectroscopy (NMOS) methods are based on new physical phenomena, providing an insight into structure from a different angle than other methods and offering new, complementary information to other spectroscopies. So far, only one of the NMOS effects (nuclear spin-induced optical rotation - NSOR) has been measured, and only in three laboratories in the world, all based in USA.
Our goal in this project were to construct a new instrument that would allow us to measure not only the so-far observed NSOR effect, but also other NMOS phenomena. We have successfully achieved the construction of the instrument that is capable of measuring the NSOR, making it the first such instrument in Europe. It is currently in principle capable of observing new NMOS effects as well with the experiments in development. The instrument itself is to be extended further in order to increase its versatility and provide access to more NMOS effects. Study of these new effects will open up a way to new spectroscopic techniques providing never before seen insight into the molecular structure of matter.
We have constructed a new instrument for observation of new NMOS phenomena. The instrument combines optical setup with electromagnet coils, which are used to manipulate nuclear spins. Because of the unique nature of the instrument, it was necessary to design it from scratch. After the initial concept phase, we explored the market for the most convenient and versatile components, both for the optical part and the electromagnet coil. The electromagnet had to be custom designed and built in order to meet the specifications. The construction has been mostly completed within the first year of the project. A significant amount of time was required for the set up of the data acquisition and instrument control, which is done via software-hardware interface to custom-written LabVIEW programs.
A notable increase in NMOS signal strength can be achieved by employing so-called hyperpolarization techniques, which allow the sample to yield a much stronger signal. After reviewing our options, it has been decided to pursue a SABRE (signal amplification by reversible exchange) hyperpolarization technique. SABRE allows to hyperpolarize a number of nuclei using a rather low cost infrastructure, in contrast to some other hyperpolarization techniques. In order to efficiently utilize this approach in our NMOS experiments, a dedicated SABRE polarizer has been designed and constructed. It has been tested and showed over two orders of magnitude stronger signal, compared to standard approach without hyperpolarization. The construction of the polarizer has taken several months, which was not taken into account in its completeness in the proposed time schedule. However, it provides us with an unexpectedly strong and versatile starting point for upcoming experiments.
The project also involved a theoretical part, where it has been shown that some of the NMOS effects reflect very sensitively structure of the electron cloud upon excitation. This may have a significant impact on the studies of excited states using NMOS methods.
The main results of the project are thus successful construction of the first NSOR instrument in Europe, which is extendable to accommodate other NMOS effects as well, and a stand-alone, unique SABRE polarizer, which can be used both in the upcoming NMOS as well as in other experiments. In addition, we have explored the applications of the NMOS effects by theoretical calculations.
The results of the theoretical calculations have been published in a peer-reviewed article and three conferences (2 presentations, 1 poster). The article documenting the SABRE polarizer is currently in preparation for publication in international journal and has already been presented at two conferences (1 presentation, 1 poster). The development of the state-of-the-art NMOS instrument towards new horizons is underway. The overall project has been presented to the general public at Researcher's night 2017.
The theoretical calculations revealed new connections between the NMOS effects and the electronic structure, which will guide the future theoretical as well as experimental progress. The SABRE polarizer developed during the project is to the best of our knowledge the only continuous-flow system of this kind, which can be used, e.g for flow imaging of hyperpolarized substances. The high modularity of our NMOS instrument is also a significant development over the previously reported setups, allowing for a wider range of setups.
The detail of the constructed instrument.